[Federal Register Volume 71, Number 215 (Tuesday, November 7, 2006)]
[Notices]
[Pages 65148-65160]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 06-9094]
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NUCLEAR REGULATORY COMMISSION
Notice of Availability of Model License Amendment Request and
Safety Evaluation on Technical Specification Improvement Regarding
Revision to the Completion Time in STS 3.6.6A, ``Containment Spray and
Cooling Systems'' for Combustion Engineering Pressurized Water Reactors
Using the Consolidated Line Item Improvement Process
AGENCY: Nuclear Regulatory Commission.
ACTION: Notice of availability.
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SUMMARY: Notice is hereby given that the staff of the U.S. Nuclear
Regulatory Commission (NRC) has prepared a model license amendment
request (LAR), model safety evaluation (SE), and model proposed no
significant hazards consideration (NSHC) determination related to
changes to the completion times (CT) in Standard Technical
Specification (STS) 3.6.6A, ``Containment Spray and Cooling Systems,''
contained in NUREG-1432 (Standard Technical Specifications for
Combustion Engineering Plants, Rev. 3.0). The proposed changes would
revise STS 3.6.6A by extending the CT for one containment spray system
(CSS) train inoperable from 72 hours to seven days, and add a
Condition, Required Actions and associated CT when one CSS train and
one containment cooling system (CCS) train are inoperable. These
changes are based on analyses provided in a joint applications report
submitted by the Combustion Engineering Owner's Group (CEOG). The CEOG
participants in the Technical Specifications Task Force (TSTF) proposed
these changes to the STS in Change Traveler No. TSTF-409, Revision 2.
The purpose of these models is to permit the NRC to efficiently
process amendments to incorporate these changes into plant-specific STS
for Combustion Engineering pressurized water reactors (PWRs). Since
TSTF-409 involves a risk-informed approach to extending the CT for one
CSS inoperable, the NRC staff must verify that licensees who apply for
this TS change have a valid, up-to-date probabilistic risk assessment
(PRA) model that employs PRA principles to ensure that public health
and safety are maintained when the CSS CT of 7 days is implemented.
Therefore, the model LAR contains several conditions requiring
licensees to make specific validations of their plant PRA quality and
methods. The intent of using the CLIIP to adopt TSTF-409 is to
eliminate
[[Page 65149]]
the need for additional technical review and requests for additional
information (RAIs) on plant-specific amendments. Licensees of nuclear
power reactors to which the models apply can request amendments
conforming to the models. In such a request, a licensee should confirm
the applicability of the model SE and NSHC determination to its plant,
and provide the expected supplemental information requested in the
model LAR.
DATES: The NRC staff issued a Federal Register Notice (71 FR 18380,
April 11, 2006) which provided for public comment a model SE, model
LAR, and NSHC determination related to changes to the CT for one CSS
train inoperable in STS 3.6.6A. The NRC staff herein provides a revised
model SE, revised model LAR, and NSHC determination. The NRC staff can
most efficiently consider applications based upon the model LAR, which
references the Model SE, if the application is submitted within one
year of this Federal Register Notice.
FOR FURTHER INFORMATION CONTACT: Tim Kobetz, Mail Stop: O-12H2,
Division of Inspection Program Management, Office of Nuclear Reactor
Regulation, U.S. Nuclear Regulatory Commission, Washington, DC 20555-
0001, telephone 301-415-1932.
SUPPLEMENTARY INFORMATION:
Background
Regulatory Issue Summary 2000-06, ``Consolidated Line Item
Improvement Process [CLIIP] for Adopting Standard Technical
Specifications Changes for Power Reactors,'' was issued on March 20,
2000. The CLIIP is intended to improve the efficiency and transparency
of NRC licensing processes. This is accomplished by processing proposed
changes to the STS in a manner that supports subsequent license
amendment applications. The CLIIP includes an opportunity for the
public to comment on proposed changes to the STS following a
preliminary assessment by the NRC staff and finding that the change
will likely be offered for adoption by licensees. The CLIIP includes
NRC staff evaluation of any comments received for a proposed change to
the STS. In several instances, the staff's evaluation did result in
changes to the model LAR and/or model SE. Those licensees opting to
apply for the subject changes to TSs are responsible for reviewing the
staff's evaluation, referencing the applicable technical
justifications, and providing any necessary plant-specific information.
The model LAR shows licensees the expected level of detail that needs
to be included in order to adopt TSTF-409, Rev. 2, as well as
guidelines for staff review. The NRC has established an internal review
plan that designates the appropriate staff and approximate timelines to
review plant-specific LARs that reference TSTF-409, Rev. 2. Each
amendment application made in response to the notice of availability
will be processed and noticed in accordance with applicable NRC rules
and procedures.
This notice involves an increase in the allowed CT to restore an
inoperable CSS train on Combustion Engineering PWRs. By letter dated
November 10, 2003, the CEOG proposed this change for incorporation into
the STS as TSTF-409, Revision 2. This change is based on the NRC staff-
approved analyses contained in CE NPSD-1045-A, ``Joint Applications
Report: Modification to the Containment Spray System, and Low Pressure
Safety Injection System Technical Specifications,'' dated March 2000,
as approved by the NRC in a SE dated December 21, 1999, accessible
electronically from the Agencywide Documents Access and Management
System's (ADAMS) Public Electronic Reading Room on the Internet (ADAMS
Accession No. ML993620241) at the NRC Web site http://www.nrc.gov/reading-rm/adams.html. Persons who do not have access to ADAMS or who
encounter problems in accessing the documents located in ADAMS, should
contact the NRC Public Document Room Reference staff by telephone at 1-
800-397-4209, 301-415-4737, or by e-mail to [email protected].
This notice, along with TSTF-409, Rev. 2, will be posted on the NRC
Web site at http://www.nrc.gov/reactors/operating/licensing/techspecs/changes-issued-for-adoption.html.
Applicability
This proposed change to revise the Technical Specification (TS) CT
for one inoperable CSS train is applicable to Combustion engineering
PWRs.
To efficiently process the incoming license amendment applications,
the NRC staff requests that each licensee applying for the changes
addressed by TSTF-409, Revision 2, use the CLIIP to submit a LAR that
adheres to the following model. Any deviations from the model LAR
should be explained in the licensee's submittal. When applying,
licensees should ensure they address the eight conditions and one
regulatory commitment listed in the model LAR and model SE.
The CLIIP does not prevent licensees from requesting an alternative
approach, proposing changes without providing the information described
in the eight model LAR conditions, or making the requested commitment.
Variations from the approach recommended in this notice may, however,
require additional review by the NRC staff and may increase the time
and resources needed for the review. Significant variations from the
approach, or inclusion of additional changes in the LAR, will result in
staff rejection of the submittal under the CLIIP. Instead, licensees
desiring significant variations and/or additional changes should either
submit a LAR that does not claim to adopt TSTF-409, or specifically
state in their LAR that they are adopting TSTF-409 without using the
CLIIP.
Public Notices
In a notice in the Federal Register dated April 11, 2006 (71 FR
18380), the staff requested comment on the use of the CLIIP to process
requests to revise the CE PWR TS regarding Containment Spray System
completion time extensions as discussed in TSTF-409. In response to
this notice, the staff received one set of comments (developed by the
PWR Owners Group, and submitted by the Nuclear Energy Institute in a
letter dating May 10, 2006 (ADAMs Accession No. ML061570029)). Specific
comments on the model LAR and model SE were offered. These comments,
along with the NRC staff's responses, are summarized and discussed
below.
1. Comment: Based on discussions with the author regarding the
intent of the ``Model SE,'' [i.e., to allow acceptance review without
RAIs while satisfying the CLIIP] it is recommended that additional
explanatory information be included. * * * At the very minimum, a clear
preamble to the FRN should be provided that places the scope of the FRN
in perspective.
Response: The following preamble has been inserted after the first
sentence of the second paragraph of the FRN.
``Since TSTF-409 involves a risk-informed approach to extending
the CT for one CSS inoperable, the NRC staff must verify that
licensees who apply for this TS change have a valid, up to date
probabilistic risk assessment (PRA) model that employs PRA
principles to ensure that public health and safety are maintained
when the CSS CT of 7 days is implemented. Therefore, the model LAR
contains several conditions requiring licensees to make specific
validations of their plant PRA quality and methods. The intent of
using the CLIIP to adopt TSTF-409 is to eliminate the need for
additional technical review and requests for additional information
(RAIs) on plant-specific amendments.''
2. Comment: [The FRN] should equally note that existing strategies
for
[[Page 65150]]
approval are valid and may also be used.
Response: The second to last paragraph of the FRN discusses how a
licensee should proceed if it desires to deviate from the approach
outlined in the CLIIP. The NRC's position is that, if a licensee is
going to submit a LAR that adopts TSTF-409 using the CLIIP, then the
plant-specific LAR should provide all the information requested in the
model LAR. Any variations/deviations should be explained, and may
require additional review by the staff (including issuance of RAIs).
Significant variations from the CLIIP methodology should be submitted
as normal license amendment requests. The staff has changed the last
sentence of second to last paragraph of the FRN to read:
``Instead, licensees desiring significant variations and/or
additional changes should either submit a LAR that does not claim to
adopt TSTF-409, or specifically state in their LAR that they are
adopting TSTF-409 without using the CLIIP.''
This will correctly define the scope of the review for the staff
when processing an incoming LAR that does not conform to the CLIIP.
3. Comment: The essence of the proposed CSS TS change focuses on a
single CSS train. Thus, the mention of ACTION G (regarding two CSS
trains out-of-service) seems unnecessary.
Response: The staff agrees with this comment. Mention of ACTION G
has been removed from Section 4.1 of the model LAR, and Section 3.1 of
the model SE.
4. Comment: The last paragraph of section 4.2.1 item 1 notes that
``If a zero maintenance PRA model is used * * * in performing these
calculations, then the licensee must commit to performing no other
maintenance during the extended CSS CT * * *''. This restriction has no
technical merit. The risk of maintenance is generated as incremental
risks from the baseline. The initial submittal noted that for plants
with emergency grade fan coolers (most of the applicants), the actual
risk increases as a result of removing a CSS out of service is very
low. Furthermore, CSS have very little (if any) overlap with other
systems. Because the risk important function of CSSs is to maintain the
containment pressure within acceptable limits (and control sump
temperature to ensure adequate NPSH for ECCS equipment--a function left
out of FRN Section 3), those functions can be accommodated by the
redundant CS train or the fan coolers. Furthermore, by using RG 1.177
to support low risk, the risk impact of removal of the CSS for the
duration of the 7 day AOT is small. Because plants perform maintenance
on a frequent basis, not allowing repair or maintenance on another
system (which is likely to be of greater risk importance than the CSS)
is unnecessary and likely to have worse risk.
Another unusual aspect of the restriction implies that the
incremental risk calculated using zero maintenance conditions is
significantly different from that calculated using annualized plant-
wide system out-of-service values. While the baseline PRA for zero
maintenance is less than the baseline PRA value for nominal
maintenance, its impact on incremental risk will be small.
Response: The staff accepts NEI's comment in that it creates a
regulatory condition that is overly restrictive to plants using a zero
maintenance PRA model. The staff has inserted alternate wording (from
RG 1.177 Section 2.3.4. 2) to the last sentence of condition 1
in Section 4.2.1 of the model LAR as follows:
If the licensee utilizes a ``zero maintenance'' PRA model for
the assessment, they should state they are using a ``zero
maintenance'' model in the evaluation, and provide a discussion as
to the ability of that model to produce comparable results to the
``average maintenance'' assessment.
5. Comment: It is understood that documented quantitative external
event information for the plants may be limited. However, reference to
plant individual plant examination (IPE) and individual plant
examination for external events (IPEEE) and the requirements to explain
the evolution of the PRA since 1988 as identified in Section in item
4.2.1 part 2.b is unnecessary. Item 2.c requires that the peer review
results be discussed along with the overall disposition of relevant
facts and observations (F&Os) and item e (which includes an overall
determination of the adequacy of the plant specific PRA with respect to
this application). These assessment[s] are current and of more
importance to the application. Where external events rely on IPEEE
vintage information, a discussion/statement of the risk significance of
the spray system in mitigating external events should be performed.
Response: The staff agrees that peer reviews of plant-specific PRA
are important. However, it is equally important to have an
understanding of PRA updates and upgrades since the IPE, IPEEE, and
peer reviews were conducted, especially if plant improvements and/or
commitments are cited and credited in the analyses as being
implemented. Licensees who have given this information in prior
submittals may incorporate the information by reference.
6. Comment: Section 4.2.1 item 3 requirements on consideration of
fire and external events and the associated EXPECTATIONS are too
restrictive and do not correspond to safety benefits. The CSS has
limited risk overlap with fires or external initiating events.
Challenges to power induced by tornadoes, high winds or seismic events
have limited importance to the spray system and [are] more appropriate
with AOTs associated with AC-power related components. It was our
understanding that the intent of this restriction was to assure the
regulator that the overall combined plant risk remains below a CDF of
10 -4 per year (per requirements of RG 1.174). The intent of
this section should be clarified. This requirement should be reduced to
providing information regarding the reasons underlying low risk
associated with this system.
Response: The staff acknowledges that, for many plants, the impact
of the CT extension on external event risk will be minimal. If this is
the case, the licensee needs to confirm this in its submittal and
explain why there is limited overlap.
7. Comment: Section 4.2.1 item 3 ACCEPTANCE CRITERIA requires
``combining internal events, internal flooding, external events and
shutdown PRA results.'' The requirements for the combination of events
should be modified to have the utility provide a technical basis for
demonstrating the plant CDF to be less than 10 -4 per year
or has no plant specific vulnerabilities (per SECY-88-20). Requirements
for a fully quantified external events (including fire) PRA and
shutdown PRA [are] beyond the state of the art. Few plants have all the
above. The Fire PRA standard is just undergoing peer review and no
shutdown PRA standard has been written. Methods for combining these PRA
results [are] also not defined (particularly merging shutdown and ``at
power'' PRA results). Instead, it should be noted that the utility may
use existing external event evaluations including IPEEE results and
qualitative external event assessments, where appropriate, to provide
confidence that the overall plant CDF is not within RG 1.174 risk
region 1.
Response: The staff is requesting that licensees provide [Delta]CDF
and [Delta]LERF calculations for those external events for which the
licensee has a PRA. For external events for which the licensee does not
have a PRA, the licensee will need to confirm there are no
vulnerabilities that would indicate that
[[Page 65151]]
the total CDF is >10-4 or the total LERF is
>10-\5\ yr. this stipulation allows the staff to ensure that
plans whose [Delta]CDF or [Delta]LERF calculation puts them in Region
II of either Figure 3 or Figure 4 of RG 1.174 are still within the RG
1.174 Section 2.2.4 acceptance guidelines for total plant risk (CDF and
LERF).
With regard to NEI's comments on a fully-quantified external events
(including fire) PRA and shutdown PRA being beyond state-of-the-art,
the staff believes the wording in the EXPECTATIONS for Section 4.2.1
condition 3 was misinterpreted. The wording has been revised to read
``(quantitatively and/or qualitatively, as appropriate).'' However, the
staff notes that while fire and shutdown PRA standards have not yet
been endorsed, there are available methods to quantify fire and
shutdown PRA. Therefore, the staff does not believe such evaluations
are beyond the state of the art. Rather, they are areas where some
evaluation is still ongoing.
8. Comment: EXPECTATIONS supporting 4.2.1 item 4. The TS is
structured to have a revised CT. Once the new CT is adopted the old CT
will disappear as a regulatory item. Thus, there is no entry into an
extended CSS CT. It is simply an entry into the CT. There are no
significant external event interactions and the outage is limited to a
single spray train. Therefore, The Tier 2 requirement should be limited
to one CSS out of service, which is already governed in the TS with a
cautionary note that Maintenance rule or tier 3 guidance to not
simultaneously disable both the emergency grade fan coolers and the
sprays.
Response: The staff agrees that ``extended CT'' should not be used
in the model LAR. Appropriate changes will be made here and in other
sections of the FRN where appropriate.
The staff believes that a tier 2 justification by the licensee is
warranted with regard to removing one CSS train from service due to
scheduled ``preventive'' maintenance for the 7-day period. If there are
no risk-significant configurations or risk-significant external event
conditions identified in the tier 2 evaluation, then the licensee
should include a statement that there are no risk-significant
configurations or external event conditions that would preclude them
from using the 7-day CT.
9. Comment: End of [Section 4.2.1 item 7]. Note that the RGs
provide guidelines. Risk values are not rigid thresholds. Thus small
deviations to the guidance can be and are somewhat fuzzy to allow for
the mathematical uncertainties inherent in these studies.
Response: The staff agrees that RG 1.174 and 1.177 guidelines are
not rigid standards, and has revised condition 7 to delete the second
paragraph of the EXPECTATIONS section. Note that Condition 5 of the
model LAR requires licensees to confirm that their CRMP or associated
(a)(4) program meets all aspects of Section 2.3.7.2 or RG 1.177.
Dated at Rockville, Maryland; this 19th day of October 2006.
For the Nuclear Regulatory Commission.
Timothy J. Kobetz,
Branch Chief, Technical Specifications Branch, Division of Inspection
and Regional Support, Office of Nuclear Reactor Regulation.
FOR INCLUSION ON THE TECHNICAL SPECIFICATION WEB PAGE THE FOLLOWING
EXAMPLE OF A LICENSE AMENDMENT REQUEST (LAR) WAS PREPARED BY THE NRC
STAFF TO FACILITATE THE ADOPTION OF TECHNICAL SPECIFICATIONS TASK FORCE
(TSTF) TRAVELER TSTF-409, REVISION 2 ``CONTAINMENT SPRAY SYSTEM
COMPLETION TIME EXTENSION (CE NPSD-1045-A).'' THE MODEL PROVIDES THE
EXPECTED LEVEL OF DETAIL AND CONTENT FOR A LAR TO ADOPT TSTF-409,
REVISION 2. LICENSEES REMAIN RESPONSIBLE FOR ENSURING THAT THEIR PLANT-
SPECIFIC LAR FULFILLS THEIR ADMINISTRATIVE REQUIREMENTS AS WELL AS NRC
REGULATIONS.
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U.S. Nuclear Regulatory Commission
Document Control Desk
Washington, DC 20555
SUBJECT: [PLANT NAME] APPLICATION FOR TECHNICAL SPECIFICATION
IMPROVEMENT TO EXTEND THE COMPLETION TIME FOR CONTAINMENT SPRAY SYSTEM
INOPERABILITY IN ACCORDANCE WITH TSTF-409, REVISION 2
Dear Sir or Madam:
In accordance with the provisions of Section 50.90 of Title 10 of
the Code of Federal Regulations (10 CFR 50.90), [LICENSEE] is
submitting a request for an amendment to the technical specifications
(TS) for [PLANT NAME, UNIT NOS.].
The proposed changes would revise TS 3.6.6A, ``Containment Spray
and Cooling Systems,'' by extending from 72 hours to seven days the
completion time (CT) to restore an inoperable containment spray system
(CSS) train. In addition, a Condition would be added to the TS to allow
one CSS train and one containment cooling system (CCS) train to be
inoperable for a period of 72 hours.
The changes are consistent with NRC-approved Industry Technical
Specification Task Force (TSTF) Standard Technical Specification Change
Traveler, TSTF-409, Revision 2, ``Containment Spray System Completion
Time Extension (CE NPSD-1045-A).''
Enclosure 1 provides a description and assessment of the proposed
changes and confirmation of applicability. Enclosure 2 provides the
existing TS pages marked-up to show the proposed changes. Enclosure 3
provides the existing TS Bases marked-up to reflect the proposed
changes (for information only). Final TS Bases will be provided in a
future update to the Updated Final Safety Analysis Report (UFSAR) in
accordance with the Bases Control Program. Attachments 1 through 8
provide the discussions of [LICENSEE'S] evaluations and supporting
information with regard to the conditions stipulated in Section 4.2.1
of Enclosure 1.
[LICENSEE] requests approval of the proposed license amendment by
[DATE], with the amendment being implemented [BY DATE OR WITHIN X
DAYS]. in accordance with 10 CFR 50.91, a copy of this application,
with enclosures, is being provided to the designated [STATE] Official.
I declare under penalty of perjury under the laws of the United
States of America that I am authorized by [LICENSEE] to make this
request and that the foregoing is true and correct. [Note that request
may be notarized in lieu of using this oath or affirmation statement].
If you should have any questions regarding this submittal, please
contact [ ].
Sincerely,
Name, Title
Enclosures:
1. Description and Assessment of Proposed Changes
2. Proposed Technical Specification Changes
3. Proposed Technical Specification Bases Changes (if applicable)
Attachments:
1. Licensee's supporting information for condition 1
2. Licensee's supporting information for condition 2
3. Licensee's supporting information for condition 3
4. Licensee's supporting information for condition 4
5. Licensee's supporting information for condition 5
6. Licensee's supporting information
[[Page 65152]]
for condition 6
7. Licensee's supporting information for condition 7
8. Licensee's supporting information for condition 8
cc:
NRR Project Manager
Regional Office
Resident Inspector
State Contact
ITSB Branch Chief
1.0 Description
The letter is a request to amend Operating License(s) [LICENSE
NUMBER(S)] for [PLANT/UNIT NAME(S)].
The proposed changes would revise Technical Specification (TS)
3.6.6A, ``Containment Spray and Cooling Systems,'' by extending from 72
hours to seven days the completion time (CT) to restore an inoperable
containment spray system (CSS) train to operable status, and would add
a Condition describing the required action and CT when one CSS train
and one containment cooling system (CCS) train are inoperable.
The changes are consistent with NRC approved Industry Owner's Group
Technical Specification Task Force (TSTF) Standard Technical
Specification Change Traveler TSTF-409, Revision 2 (Rev. 2),
``Containment Spray System Completion Time Extension (CE NPSD-1045-
A).'' TSTF-409, Rev. 2 was approved by the NRC on [DATE].
2.0 Proposed Change
Specifically, the proposed revision extends the CT (or allowed
outage time) that one CSS train is permitted to remain inoperable from
72 hours to seven days based on Reference 1, as accepted by, and
subject to the limitations specified in, Reference 2. TSTF-409, Rev. 2
states that the longer CT will enhance overall plant safety by avoiding
potential unscheduled plant shutdowns and allowing greater availability
of safety significant components during shutdown. In addition, TSTF-
409, Rev. 2 states that this extension provides for increased
flexibility in scheduling and performing maintenance and surveillance
activities in order to enhance plant safety and operational flexibility
during lower modes of operation.
The revision also adds a Condition to allow one CSS train and one
CCS train to be inoperable for up to 72 hours. Since Reference 1 did
not evaluate the concurrent inoperabilities of one CSS train and one
CCS train, the CT for this Condition was limited to 72 hours.
[LICENSEE] also proposes to make changes to the supporting TS Bases
in accordance with TSTF-409, Rev. 2. Changes to the Bases include
supporting information justifying the addition of the Condition for one
CSS train and one CCS train inoperable. The Bases changes also include
a reviewer's note that requires [LICENSEE] to adopt Reference 1 and
meet the requirements of References 1 and 2 prior to utilizing the 7-
day CT for one inoperable CSS. Finally, a reference to Reference 1 is
added to the Bases. Markups of the TS Bases are provided in enclosure
3. Changes to the Bases will be implemented in accordance with
[LICENSEE's] bases control program.
In summary, [LICENSEE] proposes to extend the CT for one inoperable
CSS train from 72 hours to 7 days based on Reference 1, and add a
Condition to allow one CSS train and one CCS train to be inoperable for
up to 72 hours.
3.0 Background
The function of the containment heat removal systems under accident
conditions is to remove heat from the containment atmosphere, thus
maintaining the containment pressure and temperature at acceptably low
levels. The systems also serve to limit offsite radiation levels by
reducing the pressure differential between the containment atmosphere
and the external environment, thereby decreasing the driving force for
fission product leakage across the containment. The two containment
heat removal systems are the CCS and the CSS. The CCS fan coolers are
designed to operate during both normal plant operations and under loss-
of-coolant accident [LOCA] or main steam line break (MSLB) conditions.
The CSS is designed to operate during accident conditions only.
The heat removal capacity of the CCS and CSS is sufficient to keep
the containment temperature and pressure below design conditions for
any size break, up to and including a double-ended break of the largest
reactor coolant pipe. The systems are also designed to mitigate the
consequences of any size break, up to and including a double-ended
break of a main stream line. The CCS and CSS continue to reduce
containment pressure and temperature and maintain them at acceptable
levels post-accident.
The CCS and CSS at [PLANT NAME] each consist of [Substitute plant-
specific configuration if it differs from the following description]
two redundant loops and are designed such that a single failure does
not degrade their ability to provide the required heat removal
capability. Two of four containment fan coolers and one CSS loop are
powered from one safety-related bus. The other two containment fan
coolers and CSS loop are powered from another independent safety-
related bus. The loss of one bus does not affect the ability of the
containment heat removal systems to maintain containment temperature
and pressure below the design values in a post-accident mode.
The [PLANT NAME] CSS consists of [Substitute plant-specific
configuration if it differs from the following description] two
independent and redundant loops each containing a spray pump, shutdown
heat exchanger, piping, valves, spray headers, and spray nozzles. It
has two modes of operation, which are:
1. The injection mode, during which the system sprays borated water
from the refueling water tank (RWT) into the containment, and
2. The recirculation mode, which is automatically initiated by the
recirculation actuation signal (RAS) after low level is reached in the
RWT. During this mode of operation, the safety injection system (SIS)
sump provides suction for the spray pumps.
Containment spray is automatically initiated by the containment
spray actuation signal coincident with the safety injection actuation
signal and high containment pressure signal. If required, the operator
can manually activate the system from the main control room.
Each CSS pump, together with a CCS loop, provides the flow
necessary to remove the heat generated inside the containment following
a LOCA or MSLB. Upon system activation, the pumps are started and the
borated water flows into the containment spray headers. When low level
is reached in the RWT, sufficient water has been transferred to the
containment to allow for the recirculation mode of operation. Spray
pump suction is automatically realigned to the SIS sump upon a RAS.
During the recirculation mode, the spray water is cooled by the
shutdown heat exchangers prior to discharge into the containment. The
shutdown heat exchangers are cooled by the component cooling water
system. Post-LOCA pH control is provided by [Substitute plant-specific
configuration if it differs from the following description] trisodium
phosphate dodecahydrate, which is stored in stainless steel baskets
located in the containment near the SIS sump intake.
The longer CT for an inoperable CSS train will enhance overall
plant safety by avoiding potential unscheduled plant
[[Page 65153]]
shutdowns and allowing greater availability of safety significant
components during shutdown. In addition, this extension provides for
increased flexibility in scheduling and performing maintenance and
surveillance activities in order to enhance plant safety and
operational flexibility during lower modes of operation.
4.0 Technical analysis
[LICENSEE] has reviewed References 1 and 2, as well as TSTF-409,
Rev. 2, and the model SE published on [DATE] ([] FR []) as part of the
CLIIP Notice of Availability. [LICENSEE] has applied the methodology in
Reference 1 to develop the proposed TS changes. [LICENSEE] has also
concluded that the justifications presented in TSTF-409, Rev. 2 and the
model SE prepared by the NRC staff are applicable to [PLANT NAME], and
justify this amendment for the incorporation of changes to the [PLANT
NAME] TS.
In determining the suitability and safety impact of its adoption of
TSTF-409, Rev. 2, [LICENSEE] analyzed the effect of increasing the CT
for one CSS train to remain out of service using both traditional
engineering considerations and probabilistic risk assessment (PRA)
methods.
4.1 Traditional (Deterministic) Engineering Analysis
The functions and operation of the CSS and CCS were described in
Section 3.0 of this application. Based on a review of the design-basis
requirements for the CSS, [LICENSEE] concluded that the loss of one CSS
train is well within the design-basis analyses. This conclusion is
based on the fact that each CSS pump, together with a CCS loop,
provides the flow necessary to remove the heat generated inside the
containment following a LOCA or MSLB. Therefore, the combination of one
CSS pump and one CCS loop can carry out the design functions of
maintaining the containment pressure and temperature at acceptably low
levels following a design-basis accident (DBA), and limiting offsite
radiation levels by reducing the pressure differential between the
containment atmosphere and the external environment, thereby decreasing
the driving force for fission product leakage across the containment.
The plant status with one CSS train and one CCS train inoperable is
covered by TS 3.6.6A, ACTION [D], which states:
``[With] one containment spray and one containment cooling train
inoperable, restore containment spray train to OPERABLE status
within 72 hours, or restore containment cooling train to OPERABLE
status within 72 hours.''
ACTION [D] ensures that the iodine removal capabilities of the CSS
are available, along with 100 percent of the heat removal needs after
an accident. The supporting analyses performed in Reference 1 did not
evaluate the concurrent inoperabilities of one CSS train and one CCS
train, therefore, the current CT of 72 hours is retained in Condition
[D]. The 72 hour Completion Time was developed taking into account the
redundant heat removal capabilities afforded by combinations of the CSS
and CCS, the iodine removal function of the CSS, and the low
probability of a DBA occurring during this period.
4.2 Probabilistic Risk Assessment Evaluation
[LICENSEE] evaluated the proposed CT extension for the CSS using
Reference 3 and Reference 4. This is the same methodology that the NRC
staff used in Reference 2. The Key Principles of A Risk-Informed
Integrated Decisionmaking Process listed in Reference 3 are as follows:
Principle I: The proposed change meets the current regulations.
Principle II: The proposed change is consistent with the defense-in-
depth philosophy.
Principle III: The proposed change maintains sufficient safety margin.
Principle IV: When the proposed change results in an increase in core
damage frequency or risk, the increase should be small and consistent
with the Commission's Safety Goal Policy Statement.
Principle V: The impact of the proposed change should be monitored
using performance measurement strategies.
In Reference 2, the NRC staff found, and [LICENSEE] agrees, that in
risk-informed TS CT applications, Principle I is met, since regulations
do not require specific CTs, but, rather, require ``remedial actions''
when an LCO cannot be met. Additionally, in its analysis of Principle
III, the NRC staff found, and [LICENSEE] agrees, that the proposed CT
extension maintains sufficient safety margins, For [PLANT NAME], the
loss of one CSS train is well within the plant's design basis.
In Reference 2, the NRC staff determined that the intent of
Principles II, IV, and V would be met by a three-tiered approach to
evaluate the plant-specific risk impact associated with the proposed TS
changes, consistent with the requirements of Reference 4. The first
tier evaluates the plant-specific PRA model and the impact of the
proposed CT extension on plant operational risk. The second tier
addresses the need to preclude potentially high risk configurations by
identifying the need for any additional constraints or compensatory
actions that, if implemented, would avoid or reduce the probability of
a risk-significant configuration during the time when one CSS train is
out of service. The third tier evaluates [LICENSEE'S] proposed
Configuration Risk Management Program (CRMP) to ensure that the
applicable plant configuration will be appropriately assessed from a
risk perspective before entering into or during the proposed CT.
In addition, the NRC staff determined in Reference 2, that the risk
analysis methodology and approach used by the CEOG to estimate the risk
impact of increasing the CT were reasonable. For most plants that
participated in the joint application report, the NRC staff found that
the risk impact was shown to be consistent with the acceptance
guidelines for change in core damage frequency ([Delta]CDF), change in
large early release frequency ([Delta]LERF), incremental conditional
core damage probability (ICCDP), and incremental conditional large
early release probability (ICLERP) specified in References 3 and 4 and
Chapters 19.0 and 16.1 of Reference 5. However, not all Combustion
Engineering (CE) plants participated in the joint application report,
and the estimated risk impacts for some plans exceeded the Reference 3
and/or Reference 4 acceptance guidelines, which would require
additional justifications and/or compensatory measures to be provided
for these plants to be determined to have acceptable risk impacts.
In addition, the NRC staff found that the Tier 2 and Tier 3
evaluations, as described in Reference 4, could not be approved
generically since they were not complete, which would require that each
individual plant-specific license amendment seeking adoption of TSTF-
409, Rev. 2 would need to include an assessment with respect to the
Tier 2 and Tier 3 principles of Reference 4.
4.2.1 Conditions and Supporting Information
The following conditions are provided to support adoption of TSTF-
409, Rev. 2 by [PLANT NAME]. Responses to the conditions are contained
in Attachments 1 through 8 to this application: [NOTE: Licensees who
cannot meet the Expectation and Acceptance Criteria listed in these
conditions, or choose not to submit the associated information, should
not
[[Page 65154]]
submit an application to adopt TSTF-409, Rev. 2 under the CLIIP.]
1. As shown in Attachment 1, the plant-specific Tier 1 information
associated with extending the CSS CT meets the acceptance guidelines of
References 3 and 4 associated with [Delta]CDF, [Delta]LERF, ICCDP, and
ICLERP.
[EXPECTATIONS/ACCEPTANCE CRITERIA: the licensee's submittal must
provide the [Delta]CDF, [Delta]LERF, ICCDP, and ICLERP values related
to the CSS 7-day CT and confirm that these values meet the associated
acceptance guidelines of References 3 and 4 as no more than a small
risk increase (i.e., are in Region II or III of the acceptance
guidelines figures). The licensee should utilize an ``average
maintenance'' PRA model for this assessment. If the licensee utilizes a
``zero maintenance'' PRA model for the assessment, they should state
they are using a ``zero maintenance'' model in the evaluation, and
provide a discussion as to the ability of that model to produce
comparable results to the ``average maintenance'' assessment.]
2. As shown in Attachment 2, the technical adequacy (quality) of
[PLANT NAME'S] plant-specific PRA is acceptable for this application in
accordance with the guidance provided in Reference 3. Specifically, the
supporting information addresses the following areas:
a. Justification that the plant-specific PRA reflects the as-built,
as-operated plant.
b. Discussion of plant-specific PRA updates and upgrades since the
individual plant examination (IPE), individual plant examination of
external events (IPEEE), and subsequent peer reviews and self-
assessment. Reference to past submittals discussing this information is
acceptable.
c. Discussion of plant-specific PRA peer reviews and/or self-
assessments performed, their overall conclusions, any facts and
observations (F&Os) applicable to this application, and the licensee
evaluation and resolution (e.g., by implementing model changes and/or
sensitivity studies) of these F&Os to demonstrate the conclusions of
the plant-specific analyses for this application are not adversely
impacted (i.e., continued acceptability of the proposed extension of
the CSS CT).
d. Description of the licensee's plant-specific PRA configuration
control (quality assurance) program and associated procedures.
e. Overall determination of the adequacy of the plant-specific PRA
with respect to this application.
[EXPECTATION: The licensee's submittal must describe the scope of
the plant-specific PRA and must justify its technical adequacy
(quality) for this application in accordance with the guidance provided
in Reference 3. Specifically, the supporting information must address
each area in sufficient detail as shown in the following ACCEPTANCE
CRITERIA:
a. The licensee must provide a justification that confirms that the
plant-specific PRA reflects the as-built, as-operated plant. This
should include a description of the licensee's data and model update
process, and the frequency of these activities. The licensee should
also describe how the plant/corporate PRA staff are involved in (and/or
made aware of) plant and operational/procedural modifications.
b. The licensee must provide a summary description of the plant-
specific PRA updates and upgrades since the IPE and peer review of
their plant and confirm that the changes identified during the IPEEE
have been implemented or otherwise dispositioned.
c. The licensee must discuss their plant-specific PRA peer reviews
and/or any self-assessments performed (especially noting those
conducted per the Nuclear Energy Institute (NEI) industry peer review
guidelines and American Society of Mechanical Engineers (ASME) PRA
Standard), their overall conclusions, any A&B level F&Os applicable to
this application, and the licensee's evaluation and resolution (e.g.,
by implementing model changes and/or sensitivity studies) of these A&B
level F&Os to demonstrate the conclusions of the plant-specific
analyses for this application are not adversely impacted (i.e.,
continued acceptability of the proposed extension of the CSS CT).
d. The licensee must describe their plant-specific PRA
configuration control (quality assurance) program and associated
procedures.
e. The licensee must make an overall determination of the adequacy
of their plant-specific PRA, confirming it is adequate with respect to
this application.]
3. Attachment 3 provides supporting information verifying that the
plant risk impact associated with external events (e.g., fires,
seismic, tornados, high winds, etc.) does not adversely impact or has
no impact on the conclusions of the plant-specific analyses for this
application and that the overall combined plant CDF and LERF are
expected to be within the acceptance guidelines as identified in
References 3 and Reference 4 (i.e., total CDF <1E-4/year and total LERF
<1E-5/year)
[EXPECTATIONS: The licensee's submittal must discuss the plant
risks associated with external events and specifically identify
(quantitatively and/or qualitatively, as appropriate) that the impact
of CSS train CT extension on the risks associated with external events
is small. The NRC staff acknowledges that any increase in the external
event risk associated with the CSS train CT extension should be
minimal. The licensee must address this impact and discuss why the risk
overlap with external events (including internal fires) is negligible.
Key insights from the IPEEE screening or quantitative approaches may be
used to support qualitative arguments.
If the licensee has performed updated analyses of an external event
since the staff review and acceptance of their IPEEE, and a
quantitative PRA demonstration is used to support the submittal, the
licensee must describe the significant changes involved in their
updated analyses and the impact of these changes on plant risk
associated with this external event and with respect to this
application.
ACCEPTANCE CRITERIA: For the NRC staff to conclude the quantified
risk associated with the extension request is acceptable, the total CDF
and LERF values must meet Reference 3 and Reference 4 acceptance
guidelines. For external events for which the licensee has a PRA, and
the licensee provides those risk values (i.e., CDF and LERF) and risk
metrics (i.e., [Delta]CDF, [Delta]LERF, ICCDP, and ICLERP) associated
with the specifically analyzed external events, the licensee must also
provide the total ``at-power'' plant risk and total ``at-power'' change
in risk due to all PRA-analyzed contributors (combining internal
events, internal flooding, internal fires, and external events. Results
may be provided as a summation of values from separate PRA analyses or
as a result of an integrated analysis (using a common PRA model for all
contributors) or a combination of the above.
For external events for which the licensee does not have a PRA (and
it is not screened out as above), but rather relies on a non-PRA method
(e.g., seismic margins analysis (SMA) or fire-induced vulnerability
evaluation (FIVE)), to determine if the plant risk is acceptable, the
licensee must confirm for this application that there were and still
are either no vulnerabilities or outliers associated with these
external events, or confirm that any vulnerabilities or outliers that
were identified in their documented analyses (most likely in their
IPEEE) have been resolved and, as needed, the appropriate
[[Page 65155]]
plant/procedural modifications have been implemented as described in
their documented analyses.]
4. Supporting information is provided in Attachment 4, consistent
with the evaluation summary and conclusions (Sections 7 and 8) provided
in Reference 2, in which licensees discuss implementation of procedures
that prohibited entry into a 7-day CSS CT for scheduled maintenance
purposes if external event conditions or warnings (e.g., severe weather
warnings for ice, tornados, high winds, etc.) are in effect or confirm
that these external events do not impact the submittal. [LICENSEE'S]
discussion confirms that [PLANT NAME'S] procedures include compensatory
measures and normal plant practices that help avoid potentially high
risk configurations during the proposed extension of the CSS CT. This
supporting information must also address the Tier 2 aspects of
Reference 4.
[EXPECTATIONS: The licensee's submittal must discuss (including
licensee commitments related to) implementation of procedures that
prohibit entry into a 7-day CSS CT for scheduled maintenance purposes
if external event conditions or warnings are in effect. If the licensee
does not want to implement this prohibition for specific severe weather
conditions or warnings, the licensee must explicitly identify these
event conditions/warnings and provide a justification for not including
them. If there are no risk significant configurations or risk
significant external event conditions identified in the Tier 2
evaluation, then the licensee should include a statement that there are
no risk significant configurations that would preclude them from using
a 7-day CT.
The licensee must also confirm that its procedures include
compensatory measures and normal plant practices that help avoid
potentially high risk configurations during the proposed extension of
the CSS train CT. This supporting information must also address the
Tier 2 aspects of Reference 4. The Tier 2 evaluation is meant to be an
early evaluation (at the license submittal stage) to identify and
preclude potentially high-risk plan configurations that could result if
equipment, in addition to that associated with the proposed license
amendment, is taken out of service simultaneously, or if other risk-
significant operational factors, such as concurrent system or equipment
testing, are also involved.
ACCEPTANCE CRITERIA: The Tier 2 evaluation needs to identify, as
part of the licensee's submittal, potentially high-risk plant
configurations associated with the CSS train CT extension that need to
be precluded, if any, and identify how this is implemented (i.e.,
typically these aspects result in licensees establishing compensatory
measures/commitments to ensure these configurations are precluded). If,
in conducting the evaluation, the licensee identifies no high-risk
plant configurations, then the licensee needs to explicitly state this
fact.]
5. Attachment 5 provides supporting information, consistent with
the evaluation summary and conclusions (Sections 7 and 8) provided in
Reference 2, that describes the plant-specific risk-informed CRMP to
assess the risk associated with the removal of equipment from service
during the 7-day CSS CT. If the licensee utilizes the Maintenance Rule
(a)(4) program to evaluate the risk significance of configurations, it
should state so in its submittal. In this description, [LICENSEE]
confirms that the program provides the necessary assurances that
appropriate assessments of plant risk configurations are sufficient to
support the proposed CSS CT extension request. This supporting
information also addresses the Tier 3 aspects of Reference 4.
[EXPECTATIONS/ACCEPTANCE CRITERIA: The licensee's submittal must
describe its CRMP or associated (a)(4) program (as appropriate),
including how it reflects the current plant PRA model (specifically
identifying any deviations and simplifications in the CRMP model from
the plant-specific PRA model) and how the CRMP is updated to remain
consistent with the plant-specific PRA.
The licensee's submittal must also describe how the CRMP or
associated (a)(4) program provides the necessary assurances that
appropriate assessments of plant risk configurations are sufficient to
support the proposed CT extension request for the CSS.
Finally, the licensee's submittal must address the Tier 3 aspects
of Reference 4, including he description of the CRMP, and must confirm
that its CRMP or associated (a)(4) program meets all aspects of Section
2.3.7.2 of Reference 4, specifically describing how its program meets
each of the four Key Components identified in this Section. The Tier 3
evaluation ensures that the CRMP or associated (a)(4) program is
adequate when maintenance is about to commence, as opposed to the early
(submittal stage) evaluation performed for Tier 2.]
6. Attachment 6 provides supporting information, consistent with
the evaluation summary (Section 7) provided in Reference 2, describing
the relationship between components of the CSS and the shutdown cooling
system (SDCS). For plants where components of the two systems may be
used as backup to the other, the licensee must either confirm that Tier
2 conditions exist in the licensee's CRMP or associated (a)(4) program
that will not allow ``at power'' maintenance of the CSS and SDCS at the
same time or that the risk significance of such maintenance
configurations is low. If the CSS and SDCS have backup components, the
plant should also describe how this backup capability is considered as
part of the plant's shutdown operations program (SOP). If this backup
feature is not considered when one train of the SDCS is in maintenance
or otherwise unavailable, it should be stated in the licensee's
application.
[EXPECTATION: The licensee's submittal must describe the
relationship/interfaces between the CSS and SDCS.
ACCEPTANCE CRITERIA: If the SDCS can be used as a backup to the
CSS, then the licensee must confirm that ``at power'' maintenance of
the CSS and SDCS will not be allowed at the same time and describe how
this is controlled (e.g., specifically identified in the CRMP as a
configuration that is not allowed) or provide justification that the
risks associated with a simultaneous ``at-power'' outage of one SDCS
train and one CSS train is small. If the SDCS cannot be used (and is
not credited) as a backup to CSS, then the licensee needs to explicitly
state this fact.
If CSS pumps can be used as a backup to the SDCS pumps, then the
licensee must confirm that at least one CSS pump is required to be
operable when maintenance of the CSS is performed in lower modes of
operation (consistent with the plant's Technical Specifications) and
must describe how this is controlled or demonstrate that the SOP
provides adequate risk management for that configuration. If CSS pumps
cannot be used (and are not credited) as a backup to SDCS pumps in
lower modes of operation, then the licensee needs to explicitly state
this fact.]
7. Attachment 7 provides supporting information confirming that the
licensee's Maintenance Rule program includes the ability to compute
ICDP (incremental core damage probability), and ILERP (incremental
large early release probability).
[EXPECTATIONS/ACCEPTANCE CRITERIA: The licensee must confirm that
their CRMP quantitative model (e.g., model used to provide quantitative
assessments in support of 10 CFR 50.65 (a)(4)) calculates ICDP and
ILERP, and
[[Page 65156]]
that their CRMP quantitative model (e.g., model used to provide
quantitative assessment in support of 10 CFR 50.65 (a)(4)) explicitly
models the CSS or has been modified to include the CSS, which will be
used whenever CSS components are made unavailable.
8. Attachment 8 provides information addressing how plant-specific
systems, structures and components (SSC) are monitored and assessed at
the plant under the Maintenance Rule (i.e. 10 CFR 50.65). Maintenance
Rule unavailability and unreliability targets for CSS are also
provided. These targets will be monitored in accordance with provisions
of the Maintenance Rule.
[EXPECTATIONS/ACCEPTANCE CRITERIA: The licensee must describe how
plant-specific SSC reliability and availability are monitored and
assessed at the plant under the Maintenance Rule (i.e., 10 CFR 50.65)
to confirm that performance continues to be consistent with the
analyses used to justify the 7-day CT. In providing this description,
the licensee should also indicate how it periodically assesses previous
risk-informed licensing action decisions to ensure that these decisions
remain valid (i.e., continue to meet the Reference 3 and Reference 4
acceptance guidelines) for the current plant operations and plant-
specific PRA and what actions it takes if a previously-approved risk-
informed licensing action decision is determined to no longer meet
these acceptance guidelines.]
4.2.2 Regulatory Commitment
The Reference 4 Tier 3 program ensures that, while the plant is
following the TS ACTIONS associated with a 7-day CT for restoring an
inoperable CSS to operable status, additional activities will not be
performed that could further degrade the capabilities of the plant to
respond to a condition that the inoperable CSS is designed to mitigate
and, as a result, increase plant risk beyond that determined by the
Reference 1 analyses. [LICENSEE's] implementation of Reference 4 Tier 3
guidelines generally implies the assessment of risk with respect to
CDF. However, the proposed CSS 7-day CT impacts accident sequences that
can be mitigated following core damage and, consequently, impacts LERF
as well as CDF. Therefore, [LICENSEE] has enhanced its CRMP, [OPTIONAL:
as implemented under 10 CFR 50.65(a)(4), the Maintenance Rule,] to
include a LERF assessment to support this application.
5.0 Regulatory Analysis
5.1 No Significant Hazards Consideration
[LICENSEE] has reviewed the proposed no significant hazards
consideration determination published in the Federal Register on [DATE]
([ ] FR [ ]) as part of the CLIP. [LICENSEE] has concluded that the
proposed determination presented in the notice is applicable to [PLANT
NAME] and the determination is hereby incorporated by reference to
satisfy the requirements of 10 CFR 50.91(a).
5.2 Applicable Regulatory Requirements/Criteria
Based on its answers to the Section 4.2.1 questions provided in
Attachments 1 through 8 to this application [LICENSEE] determines is
based on the following:
1. The traditional engineering evaluation reveals that the loss of
one CSS train is well within [PLANT NAME's] design basis analyses. Key
principles 1,2,3, and 5 in Section 2 of Reference 3 are met.
2. By meeting the conditions identified in Section 4.2.1,
[LICENSEE] believes that its PRA model is acceptable for this
application and also concludes that there is minimal impact of the CT
extensions for the CSS system on plant operational risk (Tier 1
evaluation).
3. By meeting the conditions identified in Section 4.2.1,
[LICENSEE] will ensure that its implementation will identify
potentially high risk configurations and the need for any additional
constraints or compensatory actions that, if implemented, would avoid
or reduce the probability of a risk-significant configuration (Tier 2
evaluation), or state that no Tier 2 limitations have been identified.
4. By meeting the conditions identified in Section 4.2.1, [PLANT
NAME] will ensure that its risk-informed CRMP will satisfactorily
assess the risk associated with the removal of equipment from service
during the proposed CSS CT (Tier 3 evaluation) and the CRMP and plant
risk will be managed by plant procedures, including implementation and
monitoring of SSCs (CSS).
In conclusion, based on the consideration discussed above, (1)
there is reasonable assurance that the health and safety of the public
will not be endangered by operation in the proposed manner, (2) such
activities will be conducted in compliance with the Commission's
regulations, and (3) the issuance of the amendment will not be inimical
to the common defense and security or to the health and safety of the
public.
6.0 Environmental Consideration
[LICENSEE] has reviewed the environmental evaluation included in
the model safety evaluation as pat of the CLIIP. [LICENSEE] concluded
that the staff's findings presented in that the evaluation are
applicable to [PLANT NAME] and the evaluation is hereby incorporated by
reference for this application.
7.0 References
[Licensee should include an applicable list of references,
including but not limited to]
1. Joint Applications Report: Modification to the Containment Spray
System, and Low Pressure Safety Injection System Technical, CE Owners
Group, CE NPSD-1045, March 2000.
2. Safety Evaluation by the Office of Nuclear Reactor Regulation
Related to CE Owners Group CE-NPSD-1045, ``Joint Application Report,
Modification to the Containment Spray System, and the Low Pressure
Safety Injection System Technical Specifications, December 21, 1999.''
3. USNRC Regulatory Guide 1.174, ``An Approach for Using
Probabilistic Risk Assessment in Risk-Informed Decisions on Plant-
Specific Changes to the Licensing Basis,'' Revision 1, November 2002.
4. USNRC Regulatory Guide 1.177, ``An Approach for Plant-Specific,
Risk-Informed Decisionmaking: Technical Specifications,'' August 1998.
5. NUREG-0800, ``Standard Review Plan for the Review of Safety
Analysis Reports for Nuclear Power Plants,'' June 1996.
----------------------------------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------------------------------
PROPOSED TECHNICAL SPECIFICATION CHANGES (MARK-UP)
Enclosure 2
----------------------------------------------------------------------------------------------------------------
CHANGES TO TS BASES
Enclosure 3
----------------------------------------------------------------------------------------------------------------
CONDITION (1)
[LICENSEE'S] EVALUATION AND SUPPORTING INFORMATION
[[Page 65157]]
Attachemnt 1
----------------------------------------------------------------------------------------------------------------
CONDITION (2)
[LICENSEE'S] EVALUATION AND SUPPORTING INFORMATION
Attachemnt 2
----------------------------------------------------------------------------------------------------------------
CONDITION (3)
[LICENSEE'S] EVALUATION AND SUPPORTING INFORMATION
Attachemnt 3
----------------------------------------------------------------------------------------------------------------
CONDITION (4)
[LICENSEE'S] EVALUATION AND SUPPORTING INFORMATION
Attachemnt 4
----------------------------------------------------------------------------------------------------------------
CONDITION (5)
[LICENSEE'S] EVALUATION AND SUPPORTING INFORMATION
Attachemnt 5
----------------------------------------------------------------------------------------------------------------
CONDITION (6)
[LICENSEE'S] EVALUATION AND SUPPORTING INFORMATION
Attachemnt 6
----------------------------------------------------------------------------------------------------------------
CONDITION (7)
[LICENSEE'S] EVALUATION AND SUPPORTING INFORMATION
Attachemnt 7
----------------------------------------------------------------------------------------------------------------
CONDITION (8)
[LICENSEE'S] EVALUATION AND SUPPORTING INFORMATION
Attachemnt 8
----------------------------------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------------------------------
MODEL SAFETY EVALUATION
U.S. Nuclear Regulatory Commission
Office of Nuclear Reactor Regulation
Consolidated Line Item Improvement
Technical Specification Task Force TSTF-409, Revision 2
``Containment Spray System Completion Time Extension''
1.0 Introduction
By letter to the Nuclear Regulatory Commission (NRC, Commission)
dated [DATE] (Agencywide Documents Access and Management System (ADAMS)
Accession Number MLXXXXXXXXX), [LICENSEE] (the licensee) requested
changes to the Technical Specifications (TSs) for [PLANT NAME]. The
proposed changes would revise TS 3.6.6A, ``Containment Spray and
Cooling Systems,'' by extending from 72 hours to seven days the
completion time (CT) to restore an inoperable containment spray system
(CSS) train to operable status, and would add a Condition describing
the required action and CT when one CSS train and one containment
cooling system (CCS) train are inoperable.
The changes are based on Technical Specification Task Force (TSTF)
Change Traveler, TSTF-409, Revision 2 (Rev.), ``Containment Spray
System Completion Time Extension (CE NPSD-2045-A)'' and associated TS
Bases. TSTF-409, Rev. 2, submitted to the NRC by the TSTF in a letter
dated November 10, 2003 (ADMS Accession Number MLO33280006), was
approved by the NRC on [DATE].
TSTF-409, Rev. 2 is based on Combustion Engineering Owner's Group
(CEOG) Joint Application Report CE NPSD-1045-A, ``Joint Applications
Report for Modifications to the Containment Spray System Technical
Specifications,'' dated March 2000 (Reference 1), as accepted by, and
subject to the limitations specified in, the associated NRC safety
evaluation (SE), dated December 212, 1999 (ADMS Accession Number
ML993620241) (Reference 2).
In TSTF-409, Rev. 2, the CEOG states that the longer CT for
restoring an inoperable CSS train to operable status will enhance
overall plant safety by avoiding potential unscheduled plant shutdowns
and allowing greater availability of safety significant components
during shutdown. In addition the CEOG states that this extension
provides for increased flixibility in scheduling and performing
maintenance and surveillance activities in order to enhance plant
safety and operational flexibility during lower modes of operation.
2.0 Regulatory Evaluation
Since the mid-1980's, the NRC has been reviewing and granting
improvements to TS that are based, at least in part, on probabilistic
risk assessment (PRA) insights. In its final policy statement on TX
improvements dated July 22, 1993 (58 FR 39132), the NRC stated that it:
* * * expects that licensees, in preparing their Technical
Specification related submittals, will utilize any plant-specific
PSA [probabilistic safety assessment] \1\ or risk survey and any
available literature on risk insights and PSAs * * * Similarly, the
NRC staff will also employ risk insights an PSAs in evaluating
Technical Specifications related submittals. Further, as a part of
the Commission's ongoing program of improving Technical
Specifications, it will continue to consider methods to make better
use of risk and reliability information for defining future generic
Technical Specification requirements.
---------------------------------------------------------------------------
\1\ PSA and PRA are used interchangeably herein.
The NRC reiterated this point when it issued the revision to 10 CFR
50.36, ``Technical Specifications,'' in July 1995. In August 1995, the
NRC adopted a final policy statement on the use of PRA methods in
nuclear regulatory activities that encouraged greater use of PRA to
improve safety decision-making and regulatory efficiency. The PRA
policy statement included the following points:
1. The use of PRA technology should be increased in all regulatory
matters to the extent supported by the state-of-the-art in PRA methods
and data, and in a manner that complements the NRC's deterministic
approach and supports the NRC's traditional defense-in-depth
philosophy.
2. PRA and associated analyses (e.g., sensitivity studies,
uncertainty analyses, and importance measures) should be used in
regulatory matters; where practical within the bounds of the state-
[[Page 65158]]
of-the-art, to reduce unnecessary conservatism associated with current
regulatory requirements.
3. PRA evaluations in support of regulatory decisions should be as
realistic as practicable and appropriate supporting data should be
publicly available for review.
In March 1998, the CEOG submitted a joint applications report for
the NRC staff's review entitled, ``Joint Applications Report for
Modifications to the Containment Spray System and Low Pressure Safety
System Technical Specifications.'' The NRC review accepting this joint
applications report for referencing in license applications for
Combustion Engineering (CE) plants, including appropriate exclusions,
conditions, and limitations, is documented in Reference 2. The final,
NRC-approved joint applications report, (Reference 1) is dated March
2000.
3.0 Technical Evaluation
The NRC staff evaluated the licensee's proposed amendment to extend
the TS CT for one CSS train out of service from 72 hours to seven days
using insights derived from traditional engineering considerations and
the use of PRA methods to determine the safety impact of extending the
CT.
3.1 Traditional Engineering Evaluation
The function of the containment heat removal systems under accident
conditions is to remove heat from the containment atmosphere, thus
maintaining the containment pressure and temperature at acceptably low
levels. The systems also serve to limit offsite radiation levels by
reducing the pressure differential between the containment atmosphere
and the external environment, thereby decreasing the driving force for
fission product leakage across the containment. The two containment
heat removal systems are the CCS and CSS. The CCS fan coolers are
designed to operate during both normal plant operations and under loss-
of-coolant accident (LOCA) or main stream line break (MSLB) conditions.
The CSS is designed to operate during accident conditions only.
The heat removal capacity of the CCS and CSS is sufficient to keep
the containment temperature and pressure below design conditions for
any size break, up to and including a double-ended break of the largest
reactor coolant pipe. The systems are also designed to mitigate the
consequences of any size break, up to and including a double-ended
break of a main stream line. The CCS and CSS continue to reduce
containment pressure and temperature and maintain them at acceptable
levels post-accident.
The CCS and CSS at [PLANT NAME] each consist of [Substitute plant-
specific configuration if it differs from the following description]
two redundant loops and are designed such that a single failure does
not degrade their ability to provide the required heat removal
capability. Two of four containment fan coolers and one CSS loop are
powered from one safety-related bus. The other two containment fan
coolers and one CSS loop are powered from another independent safety
related bus. The loss of one bus does not affect the ability of the
containment heat removal systems to maintain containment temperature
and pressure below the design values in a post-accident mode.
The [PLANT NAME] CSS consists of [Substitute plant-specific
configuration if it differs from the following description] two
independent and redundant loops each containing a spray pump, shutdown
heat exchanger, piping, valves, spray headers, and spray nozzles. It
has two modes of operation, which are:
1. The injection mode, during which the system sprays borated water
from the refueling water tank (RWT) into the containment, and
2. The recirculation mode, which is automatically initiated by the
recirculation actuation signal (RAS) after low level is reached in the
RWT. During this mode of operation, the safety injection system (SIS)
sump provides suction for the spray pumps.
Containment spray is automatically initiated by the containment
spray actuation signal coincident with the safety injection actuation
signal and high containment pressure signal. If required, the operator
can manually activate the system from the main control room.
Each CSS pump, together with a CCS loop, provides the flow
necessary to remove the heat generated inside the containment following
a LOCA or MSLB. Upon system activation, the pumps are started, and
borated water flows into the containment spray headers. When low level
is reached in the RWT, sufficient water has been transferred to the
containment to allow for the recirculation mode of operation. Spray
pump suction is automatically realigned to the SIS sump upon a RAS.
During a recirculation mode, the spray water is cooled by the
shutdown heat exchangers prior to discharge into the containment. The
shutdown heat exchangers are cooled by the component cooling water
system. Post-LOCA pH control is provided by [Substitute plant-specific
configuration if it differs from the following description] trisodium
phosphate dodecahydrate, which is stored in stainless steel baskets
located in the containment near the SIS sump intake.
Based on a review of the design-basis requirements for the CSS, the
NRC staff concluded that the loss of one CSS train is well within the
design-basis analyses. The plant status with one CSS train and one CCS
train inoperable is covered by TS3.6.6A, ACTION D, which states:
``[With] one containment spray and one containment cooling train
inoperable, restore containment spray train to OPERABLE status
within 72 hours, or restore containment cooling train to OPERABLE
status within 72 hours.''
ACTION D ensures that the iodine removal capabilities of the CSS
are available, along with 100 percent of the heat removal needs after
an accident. The supporting analyses performed in Reference 1 did not
evaluate the concurrent inoperabilities of one CSS train and one CCS
train. Therefore, the current CT of 72 hours is retained in Condition
D. The 72-hour CT was development taking into account the redundant
heat removal capabilities afforded by combinations of the CSS and CCS,
the iodine removal function of the CSS, and the low probabilities of a
DBA occurring during this period.
3.2 Probabilistic Risk Assessment Evaluation
The proposed extension of the CSS CT for one inoperable train from
72 hours to seven days affects plant risk by impacting:
1. Accident sequences that can be prevented from leading to core
damage.
2. Accident sequences that can be mitigated following core damage.
The CSS therefore affects both core damage frequency (CDF) and
large early release frequency (LERF). This is because the CSS performs
the critical function of controlling containment temperature and
pressure to cool the reactor coolant system (RCS) inventory that is
spilled in the sump as a result of a LOCA (core damage prevention role)
and preventing the release of radionuclides subsequent to a core damage
event (core damage and radionuclide release mitigation role).
[The following paragraph will contain plant-specific information
based on the plant's ability to use the shutdown cooling system (SDCS)
as a backup to the CSS. The licensee should provide a plant-specific
system configuration description based on whether its SDCS can be used
a backup to the CSS pump.]
The proposed CT extension also impacts the long-term cooling
function
[[Page 65159]]
that can be provided by the SDCS following a small-break LOCA, steam
generator tube rupture (SGTR), or MSLB. If entry into the 7-day CT is
caused by a CSS pump outage, the plants with the ability to use the
SDCS as a backup to the CSS pump can still preserve the spray function
of the affected train. If, however, a SDCS heat exchanger is removed
from service, then both the CSS and SDCS capability of the affected
train would be lost unless cross-connect capability with another
unaffected system (e.g., service water) is possible. However, this
cross-connect capability should not be credited unless it is
proceduralized.
The NRC staff used a three-tiered approach to evaluate the plant-
specific risk impact associated with the proposed TS changes. The first
tier evaluates the plant-specific PRA model and the impact of the
proposed CT extension on plant operational risk. The second tier
addresses the need to preclude potentially high risk configurations by
identifying the need for any additional constraints or compensatory
actions that, if implemented, would avoid or reduce the probability of
a risk-significant configuration during the time when on CSS train is
out of service. The third tier evaluates the licensee's proposed
Configuration Risk Management Program (CRMP) to ensure that the
applicable plant configuration will be appropriately assessed from a
risk perspective before entering into, or during, the proposed CT.
In Reference 2, the NRC staff found that the risk analysis
methodology and approach used by the CEOG to estimate the risk impact
were reasonable. In its SE, the NRC staff also stated that, for most
plants that participated in the joint application report, the risk
impact can be shown to be consistent with the acceptance guidelines for
change in CDF ([Delta]CDF), change in LERF ([Delta]LERF), incremental
conditional core damage probability (ICCDP), and incremental large
early release frequency (ICLERP) specified in Regulatory Guide (RG)
1.174 (Reference 3) and RG 1.177 (Reference 4) and the associated
Standard Review Plan (SRP) Chapters 19.0 and 16.1 of NUREG-0800
(Reference 5). However, not all CE plants participated in the joint
application report, and the estimated risk impacts for some plants
exceeded the Reference 3 and/or Reference 4 acceptance guidelines,
which would require additional justifications and/or compensatory
measures to be provided for these plants to be determined to have
acceptable risk impacts.
In Reference 2, the NRC staff also found that the Tier 2 and Tier 3
evaluations, as described in Reference 4, could not be approved
generically since they were not complete from the perspective of
addressing plant-specific Tier 2 and Tier 3 issues which would require
that each individual plant-specific license amendment seeking approval
through TSTF-409, Rev. 2 would need to include an assessment with
respect to the Tier 2 and Tier 3 principles of Reference 4.
Based on the above discussion, the NRC staff identified conditions
that must be addressed in the licensee's plant-specific application
requesting adoption of TSTF-409, Revision 2. In its application dated
[DATE], the licensee provided supporting information for each of the
conditions which met the NRC staff's expectations and acceptance
criteria [with the following exceptions: list any exceptions to the
conditions stated in the model LAR].
[Provide a discussion of any significant plant-specific exceptions
to or modifications of the conditions described in the model LAR].
3.2.1 Commitment
The Reference 4 Tier 3 program ensures that, while the plant is
following the TS ACTIONS associated with a 7-day CT for restoring an
inoperable CSS to operable status, additional activities will not be
performed that could further degrade the capabilities of the plant to
respond to a condition that the inoperable CSS is designed to mitigate
and, as a result, increase plant risk beyond that determined by the
Reference 1 analyses. A licensee's implementation of Reference 4 Tier 3
guidelines indicates that it has assessed risk with respect to CDF.
However, the proposed CSS 7-day CT impacts accident sequences that can
be mitigated following core damage and, consequently, LERF as well as
CDF. Therefore, the licensee enhnaced its CRMP [optional: as
implemented under 10 CFR 50.65(a)(4), the Maintenance Rule,] to include
a LERF assessment. [The licensee should confirm that performance of
LERF assessments is included in the plant's Maintenance Rule program.]
3.3 Summary
On [DATE], ([ ] FR [ ]), the NRC announced the availability of
TSTF-409, Rev. 2 for adoption by licensees using the consolidated line
item improvement program (CLIIP). In its model license amendment
request (LAR), the NRC staff asked each licensee to verify several
aspects of its plant-specific PRA program including: 1) verification of
PRA quality, 2) plant-specific analyses of the impact of this TS change
on overall risk, 3) Maintenance Rule and CRMP considerations associated
with the proposed changes, and, 4) system interdependencies. In its
[DATE] submittal, the licensee provided satisfactory information
related to the eight conditions and one licensee commitments set forth
in the model LAR.
Having met the conditions identified in the model LAR, the NRC
staff finds that the licensee's plant-specific LAR is consistent with
the previous NRC staff approval of Reference 1, as documented in
Reference 2 and TSTF-409, Rev. 2, and thus is acceptable. This
determination is based on the following:
1. The traditional engineering evaluation reveals that the loss of
one CSS train is well within the design-basis analyses.
2. Since the licensee meets the conditions identified in the model
LAR, the NRC staff finds that there is minimal impact of the CT
extensions for the CSS system on plant operational risk (Tier 1
evaluation).
3. Meeting the conditions identified in the model LAR will ensure
that the licensee's implementation will identify potentially high risk
configurations and the need for any additional constraints or
compensatory actions that, if implemented, would avoid or reduce the
probability of a risk-significant configuration (Tier 2 evaluation).
4. Meeting the conditions identified in the model LAR will ensure
that the risk-informed CRMP proposed by the licensee will
satisfactorily assess the risk associated with the removal of equipment
from service during the proposed CSS CT (Tier 3 evaluation) and the
CRMP and plant risk will be managed by plant procedures.
4.0 Regulatory Commitment
The licensee's letter dated [DATE], contained the following
regulatory commitment: [STATE THE LICENSEE'S COMMITMENT AND ENSURE THAT
IT SATISFIES THE COMMITMENT IN SECTION 3.2.1 OF THIS SE].
The NRC staff finds that reasonable controls for the implementation
and for subsequent evaluation of proposed changes pertaining to the
above regulatory commitment are best provided by the licensee's
administrative controls process, including its commitment management
program. The above regulatory commitment does not warrant the creation
of a license condition (item requiring prior NRC approval of subsequent
changes).
[[Page 65160]]
5.0 State Consultation
In accordance with the Commission's regulations, the [STATE] State
official was notified of the proposed issuance of the amendment[s]. The
State official had [CHOOSE ONE: (1) No comments, OR (2) the following
comments--with subsequent disposition by the staff].
6.0 Environmental Consideration
The amendment changes a requirement with respect to the
installation or use of a facility component located within the
restricted area as defined in 10 CFR Part 20. The NRC staff has
determined that the amendment involves no significant increase in the
amounts, and no significant change in the types, of any effluents that
may be released offsite, and that there is no significant increase in
individual or cumulative occupational radiation exposure. The
Commission has previously issued a proposed finding that the amendment
involves no significant hazards consideration, and there has been no
public comment on such finding [(XX FR XXXXX, dated Monthly DD, YYYY)].
Accordingly, the amendment meets the eligibility criteria for
categorical exclusion set forth in 10 CFR 51.22(c)(9). Pursuant to 10
CFR 51.22(b), no environmental impact statement or environmental
assessment need be prepared in connection with the issuance of the
amendment.
7.0 Conclusion
The Commission has concluded, based on the considerations discussed
above, that (1) there is reasonable assurance that the health and
safety of the public will not be endangered by operation in the
proposed manner, (2) such activities will be conducted in compliance
with the Commission's regulations, and (3) the issuance of the
amendment will not be inimical to the common defense and security or to
the health and safety of the public.
8.0 References
1. Joint Applications Report: Modification to the Containment Spray
System, and Low Pressure Safety Injection System Technical, CE
Owners Group, CE NPSD-1045, March 2000.
2. SE by the Office of Nuclear Reactor Regulation Related to CE
Owners Group CE-NPSD-1045, ``Joint Application Report, Modification
to the Containment Spray System, and the Low Pressure Safety
Injection System Technical Specifications,'' December 21, 1999.
3. U.S. NRC RG 1.174, ``An Approach for Using Probabilistic Risk
Assessment in Risk-Informed Decisions on Plant-Specific Changes to
the Licensing Basis,'' Revision 1, November 2002.
4. U.S. NRC RG 1.177, ``An Approach for Plant-Specific, Risk-
Informed Decisionmaking: Technical Specifications,'' August 1998.
5. NUREG-0800, ``Standard Review Plan for the Review of Safety
Analysis Reports for Nuclear Power Plants,'' June 1996.
Model No Significant Hazards Consideration
Description of Amendment Request: The proposed amendment would
revise the technical specifications to extend the completion time (CT)
from 72 hours to seven days to restore an inoperable containment spray
system (CSS) train to operable status, and add a Condition describing
the required Actions and CT when one CSS and one containment cooling
system (CCS) are inoperable.
Basis for proposed no significant hazards consideration
determination: As required by 10 CFR 50.91(a), an analysis of the issue
of no significant hazards consideration is presented below:
1. Does the proposed change involve a significant increase in the
probability or consequences of an accident previously evaluated?
Response: No.
The proposed change extends from 72 hours to 7 days the CT for
restoring an inoperable CSS train to operable status. Being in an
ACTION is not an initiator of any accident previously evaluated.
Consequently, the probability of an accident previously evaluated is
not significantly increased. The consequences of an accident while
relying on ACTIONS during the 7-day CT are no different than the
consequences of an accident while relying on the ACTION during the
existing 72-hour CT. Therefore, the consequences of an accident
previously evaluated are not significantly increased by this change.
Therefore, this change does not involve a significant increase in the
probability or consequences of an accident previously evaluated.
2. Does the change create the possibility of a new or different
kind of accident from any accident previously evaluated?
Response: No.
The proposed change extends from 72 hours to 7 days the CT for
restoring an inoperable CSS train to operable status. The proposed
change does not involve a physical alteration of the plant (no new or
different type of equipment will be installed) or a change in the
methods governing normal plant operation. Thus, this change does not
create the possibility of a new or different kind of accident from any
accident previously evaluated.
3. Does the proposed change involve a significant reduction in a
margin of safety?
Response: No.
The proposed change extends from 72 hours to 7 days the CT for
restoring an inoperable CSS train to operable status. The licensee
performed risk-based evaluations using its plant-specific probabilistic
risk assessment (PRA) model in order to determine the effect of this
change on plant risk. The PRA evaluations were based on the conditions
stipulated in NRC staff safety evaluations approving both Joint
Applications Report CE NPSD-1045-A, ``Joint Applications Report,
Modifications to the Containment Spray System and The Low Pressure
Safety Injection System Technical Specifications,'' and Technical
Specification Task Force Change Traveler, TSTF-409, Revision 2,
``Containment Spray System Completion Time Extension (CE NPSD-1045-
A).'' The results of these plant-specific evaluations determined that
the effect of the proposed change on plant risk is very small.
Therefore, this change does not involve a significant reduction in a
margin of safety.
Based on the above, the proposed change involves no significant
hazards consideration under the standards set forth in 10 CFR 50.92(c),
and accordingly, a finding of no significant hazards consideration is
justified.
Dated at Rockville, Maryland, this XX day of XXXXXXXX, 2006.
FOR THE NUCLEAR REGULATORY COMMISSION
Project Manager
Plant Licensing Branch [ ]
Division of Operating Reactor Licensing
Office of Nuclear Reactor Regulation
[FR Doc. 06-9094 Filed 11-6-06; 8:45 am]
BILLING CODE 7590-01-M