[Federal Register Volume 68, Number 186 (Thursday, September 25, 2003)]
[Notices]
[Pages 55416-55421]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 03-24204]
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NUCLEAR REGULATORY COMMISSION
Notice of Availability of Model Application Concerning Technical
Specification Improvement To Eliminate Hydrogen Recombiner Requirement,
and Relax the Hydrogen and Oxygen Monitor Requirements for Light 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 Nuclear
Regulatory Commission (NRC) has prepared a model safety evaluation
(SE), a model no significant hazards consideration (NSHC)
determination, and a model application relating to the elimination of
hydrogen recombiner requirements, and relaxation of the hydrogen and
oxygen monitor requirements for Light Water Reactors (LWRs). The
purpose of these models is to permit the NRC to efficiently process
amendments that propose to remove requirements for hydrogen
recombiners, and hydrogen and oxygen monitors from Technical
Specifications (TS). Licensees of nuclear power reactors to which the
models apply may request amendments using the model application.
DATES: The NRC staff issued a Federal Register Notice (67 FR 50374,
August 2, 2002) soliciting comments on a model safety SE and a model
NSHC determination for the elimination of requirements for hydrogen
recombiners, and hydrogen and oxygen monitors from TS. The NRC staff
hereby announces that the attached model SE and model NSHC
determination (which differ only slightly from the versions previously
published) may be referenced in plant-specific applications to
eliminate requirements for hydrogen recombiners, and hydrogen and
oxygen monitors from TS. The staff has posted a model application on
the NRC web site to assist licensees in using the consolidated line
item improvement process (CLIIP) to apply for the proposed TS change.
The NRC staff can most efficiently consider applications based upon the
model application if the application is submitted within a year of this
Federal Register Notice.
FOR FURTHER INFORMATION CONTACT: William Reckley, Mail Stop: O-7D1,
Division of Licensing Project Management, Office of Nuclear Reactor
Regulation, U.S. Nuclear Regulatory Commission, Washington, DC 20555-
0001, telephone 301-415-1323.
[[Page 55417]]
SUPPLEMENTARY INFORMATION:
Background
Regulatory Issue Summary 2000-06, ``Consolidated Line Item
Improvement Process for Adopting Standard Technical Specification
Changes for Power Reactors,'' was issued on March 20, 2000. The CLIIP
is intended to improve the efficiency of NRC licensing processes. This
is accomplished by processing proposed changes to the standard
technical specifications (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 NRC staff
evaluates any comments received for a proposed change to the STS and
either reconsiders the change or proceeds with announcing the
availability of the change for proposed adoption by licensees. Those
licensees opting to apply for the subject change to TS are responsible
for reviewing the staff's evaluation, referencing the applicable
technical justifications, and providing any necessary plant-specific
information. Each amendment application made in response to the notice
of availability will be processed and noticed in accordance with
applicable rules and NRC procedures.
This notice involves the elimination of requirements for hydrogen
recombiners, and hydrogen and oxygen monitors in TS for LWRs. This
proposed change was proposed for incorporation into the STS and is
designated TSTF-447, Revision 1. TSTF-447, Revision 1 is supported by
the implementation of a revision to 10 CFR 50.44, ``Standards for
Combustible Gas Control System in Light-Water-Cooled Power Reactors.''
The amended standards eliminated the need for requirements for hydrogen
recombiners and for hydrogen and oxygen monitors in TS. TSTF-447,
Revision 1 can be viewed on the NRC Web site (www.nrc.gov).
Applicability
This proposed change to remove requirements for hydrogen
recombiners, and hydrogen and oxygen monitors from TS is applicable to
LWRs (i.e., all operating plants).
To efficiently process the incoming license amendment applications,
the staff requests each licensee applying for the changes addressed by
TSTF-447, Revision 1 using the CLIIP to address the following plant-
specific verifications and regulatory commitments. The CLIIP does not
prevent licensees from requesting an alternative approach or proposing
the changes without the requested verifications and regulatory
commitments. 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. In making the
requested regulatory commitments, each licensee should state: (1) That
the subject capability exists (or will be developed) and will be
maintained; (2) where the capability or procedure will be described
(e.g., severe accident management guidelines, emergency operating
procedures, emergency plan implementing procedures); and (3) a schedule
for implementation. The amendment request need not provide details
about designs or procedures.
Each licensee should verify that it has, and make a regulatory
commitment to maintain (or make a regulatory commitment to develop and
maintain):
a. A hydrogen monitoring system capable of diagnosing beyond
design-basis accidents; and
b. An oxygen monitoring system capable of verifying the status of
the inert containment for plant designs with an inerted containment.
(for applicable boiling water reactors)
Public Notices
In a notice in the Federal Register dated August 2, 2002 (67 FR
50374), the staff requested comment on the use of the CLIIP to process
requests to delete hydrogen recombiner, and hydrogen and oxygen monitor
requirements from TS.
TSTF-447, Revision 1, and documents associated with the revision of
10 CFR 50.44 may be examined, and/or copied for a fee, at the NRC's
Public Document Room, located at One White Flint North, Public File
Area O1 F1, 11555 Rockville Pike (first floor), Rockville, Maryland.
Publicly available records are accessible electronically from the ADAMS
Public Library (the Electronic Reading Room) component on the NRC Web
site (www.nrc.gov).
The staff received one comment (from an individual licensee)
following the notice soliciting comments about modifying the TS
requirements regarding hydrogen recombiners, and hydrogen and oxygen
monitors for LWRs. The comment on the model SE was offered, and is
summarized and discussed below:
1. Comment: A licensee recommended that the SE also include
conclusions as to the acceptability of eliminating containment purging
as the design basis method for post-loss-of-coolant accident (LOCA)
hydrogen control. Some licensees use containment purging as the design
basis method for compliance with the current 10 CFR 50.44, rather than
hydrogen recombiners. Although the containment purge requirements were
not incorporated into the TS, as was done for hydrogen recombiners, the
requirement for purging exists in docketed commitments to the NRC and
in the Final Safety Analysis Report (FSAR). The process of changing the
FSAR and the docketed commitments would be simplified if the NRC SE
included consideration of containment purging.
Response: The NRC model SE only addresses requirements in the STS
or plant-specific TS. In this case, the NRC model SE is for the
elimination of the requirements of hydrogen recombiners, and hydrogen
and oxygen monitors from TS. Since containment purging requirements are
not in the STS, the NRC model SE did not make conclusions about the
acceptability of eliminating containment purging as the design basis
method for post-LOCA hydrogen control. However, the following statement
from the Statements of Considerations was added to the model SE to
address the comment:
* * * the Commission eliminated the hydrogen release associated
with a design-basis LOCA from Sec. 50.44 and the associated
requirements that necessitated the need for the hydrogen recombiners
and the backup hydrogen vent and purge systems.
In addition, the staff has made some minor changes to the model SE
as a result of internal reviews. A specific change involves the
reference to Criterion 2 (10 CFR 50.36(c)(2)(ii)(B)) as the basis for
retention of primary containment oxygen concentration in the TS. In the
model SE, the staff had proposed to change the basis to Criterion 4 (10
CFR 50.36(c)(2)(ii)(D)) since combustible gas generated from severe
accidents was not risk significant for Mark I and II containments,
provided that the required inerted atmosphere was maintained. Criterion
4 is intended to capture those constraints that probabilistic risk
assessment or operating experience show to be significant to public
health and safety, consistent with the Commission's Probabilistic Risk
Assessment (PRA) Policies. Upon further review by the staff, it was
determined that the basis for the primary containment oxygen
concentration should remain Criterion 2 since the typical Updated FSAR
Chapter 6 analyses assume that the primary containment is inerted when
a design basis LOCA occurs. Therefore, primary containment oxygen
concentration is a
[[Page 55418]]
process variable, design feature, or operating restriction that is an
initial condition of a design basis accident or transient analysis that
either assumes the failure of or presents a challenge to the integrity
of a fission product barrier.
Licensees wishing to eliminate the requirements for hydrogen
recombiners, and hydrogen and oxygen monitors from TS must submit an
application in accordance with applicable regulatory requirements. As
described in the model application prepared by the staff, licensees may
reference the following model SE, NSHC determination, and environmental
assessment in their plant-specific applications to eliminate the TS
requirements for hydrogen recombiners, and hydrogen and oxygen
monitors.
Model Safety Evaluation--U.S. Nuclear Regulatory Commission, Office of
Nuclear Reactor Regulation, Consolidated Line Item Improvement,
Technical Specification Task Force (TSTF) Change TSTF-447, Revision 1,
Elimination of Requirements for Hydrogen Recombiners and Change of
Requirements for Hydrogen and Oxygen Monitors
1.0 Introduction
By application dated [ ], [Licensee] (the licensee) requested
changes to the Technical Specifications (TSs) for [Plant]. The proposed
changes would delete the TS requirements associated with hydrogen
recombiners, and hydrogen [and oxygen] monitors.
The Nuclear Regulatory Commission (NRC) has revised 10 CFR 50.44,
``Standards for Combustible Gas Control System in Light-Water-Cooled
Power Reactors.'' The amended standards eliminated the requirements for
hydrogen recombiners and relaxed the requirements for hydrogen and
oxygen monitoring. In letters dated December 17, 2002, and May 12,
2003, the Nuclear Energy Institute (NEI) Technical Specification Task
Force (TSTF) proposed to remove requirements for hydrogen recombiners
and hydrogen and oxygen monitors from the standard technical
specifications (STS) (NUREGs 1430-1434) on behalf of the industry to
incorporate the amended standards. This proposed change is designated
TSTF-447.
The NRC staff prepared this model safety evaluation (SE) for the
elimination of requirements regarding containment hydrogen recombiners
and the removal of requirements from TS for containment hydrogen and
oxygen monitors and solicited public comment (67 FR 50374, published
August 2, 2002) in accordance with the Consolidated Line Item
Improvement Process (CLIIP). The use of the CLIIP in this matter is
intended to help the NRC to efficiently process amendments that propose
to remove the hydrogen recombiner and hydrogen and oxygen monitor
requirements from TS. Licensees of nuclear power reactors to which this
model applies were informed [FR] that they could request amendments
conforming to the model, and, in such requests, should confirm the
applicability of the SE to their reactors and provide the requested
plant-specific verifications and commitments.
2.0 Background
Regulatory Issue Summary 2000-06, ``Consolidated Line Item
Improvement Process for Adopting Standard Technical Specification
Changes for Power Reactors,'' was issued on March 20, 2000. The CLIIP
is intended to improve the efficiency 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 NRC staff evaluates any comments received for a proposed
change to the STS and either reconsiders the change or proceeds with
announcing the availability of the change for proposed adoption by
licensees. Those licensees opting to apply for the subject change to TS
are responsible for reviewing the staff's evaluation, referencing the
applicable technical justifications, and providing any necessary plant-
specific information. Each amendment application made in response to
the notice of availability would be processed and noticed in accordance
with applicable rules and NRC procedures.
The Commission's regulatory requirements related to the content of
TS are set forth in 10 CFR 50.36. This regulation requires that the TSs
include items in five specific categories. These categories include (1)
Safety limits, limiting safety system settings and limiting control
settings, (2) limiting conditions for operation (LCO), (3) surveillance
requirements, (4) design features, and (5) administrative controls.
However, the regulation does not specify the particular TSs to be
included in a plant's license.
Additionally, 10 CFR 50.36(c)(2)(ii) sets forth four criteria to be
used in determining whether an LCO is required to be included in the
TS. These criteria are as follows:
1. Installed instrumentation that is used to detect, and indicate
in the control room, a significant abnormal degradation of the reactor
coolant pressure boundary.
2. A process variable, design feature, or operating restriction
that is an initial condition of a design-basis accident or transient
analysis that assumes either the failure of or presents a challenge to
the integrity of a fission product barrier.
3. A structure, system, or component that is part of the primary
success path and which functions or actuates to mitigate a design-basis
accident or transient that either assumes the failure of or presents a
challenge to the integrity of a fission product barrier.
4. A structure, system or component which operating experience or
probabilistic risk assessment has shown to be significant to public
health and safety.
Existing LCOs and related surveillances included as TS requirements
which satisfy any of the criteria stated above must be retained in the
TSs. Those TS requirements which do not satisfy these criteria may be
relocated to other licensee-controlled documents.
As part of the rulemaking that revised 10 CFR 50.44, the Commission
retained requirements for ensuring a mixed atmosphere, inerting Mark I
and II containments, and providing hydrogen control systems capable of
accommodating an amount of hydrogen generated from a metal-water
reaction involving 75 percent of the fuel cladding surrounding the
active fuel region in Mark III and ice condenser containments. The
Commission eliminated the design-basis loss-of-coolant accident (LOCA)
hydrogen release from 10 CFR 50.44 and consolidated the requirements
for hydrogen and oxygen monitoring to 10 CFR 50.44 while relaxing
safety classifications and licensee commitments to certain design and
qualification criteria. The Commission also relocated without change
the hydrogen control requirements in 10 CFR 50.34(f) to 10 CFR 50.44
and the high point vent requirements from 10 CFR 50.44 to 10 CFR
50.46a.
3.0 Evaluation
The ways in which the requirements and recommendations for
combustible gas control were incorporated into the licensing bases of
commercial nuclear power plants varied as a function of when plants
were licensed. Plants that were operating at the time of the Three Mile
Island (TMI), Unit 2 accident are
[[Page 55419]]
likely to have been the subject of confirmatory orders that imposed the
combustible gas control functions described in NUREG-0737,
``Clarification of TMI Action Plan Requirements,'' as obligations. The
issuance of plant specific amendments to adopt these changes, which
would remove hydrogen recombiner and hydrogen and oxygen monitoring
controls from TS, supersede the combustible gas control specific
requirements imposed by post-TMI confirmatory orders.
3.1 Hydrogen Recombiners
The revised 10 CFR 50.44 no longer defines a design-basis LOCA
hydrogen release, and eliminates requirements for hydrogen control
systems to mitigate such a release. The installation of hydrogen
recombiners and/or vent and purge systems required by 10 CFR
50.44(b)(3) was intended to address the limited quantity and rate of
hydrogen generation that was postulated from a design-basis LOCA. The
Commission has found that this hydrogen release is not risk-significant
because the design-basis LOCA hydrogen release does not contribute to
the conditional probability of a large release up to approximately 24
hours after the onset of core damage. In addition, these systems were
ineffective at mitigating hydrogen releases from risk-significant
beyond design-basis accidents. Therefore, the Commission eliminated the
hydrogen release associated with a design-basis LOCA from 10 CFR 50.44
and the associated requirements that necessitated the need for the
hydrogen recombiners and the backup hydrogen vent and purge systems. As
a result, the staff finds that requirements related to hydrogen
recombiners no longer meet any of the four criteria in 10 CFR
50.36(c)(2)(ii) for retention in TS and may be relocated to other
licensee-controlled documents for all plants.
3.2 Hydrogen Monitoring Equipment
Section 50.44(b)(1), the STS, and plant-specific TS currently
contain requirements for monitoring hydrogen. Licensees have also made
commitments to design and qualification criteria for hydrogen monitors
in Item II.F.1, Attachment 6 of NUREG-0737 and Regulatory Guide (RG)
1.97, ``Instrumentation for Light-Water-Cooled Nuclear Power Plants to
Assess Plant and Environs Conditions During and Following an
Accident.'' The hydrogen monitors are required to assess the degree of
core damage during a beyond design-basis accident and confirm that
random or deliberate ignition has taken place. If an explosive mixture
that could threaten containment integrity exists during a beyond
design-basis accident, then other severe accident management
strategies, such as purging and/or venting, would need to be
considered. The hydrogen monitors are needed to implement these severe
accident management strategies.
With the elimination of the design-basis LOCA hydrogen release,
hydrogen monitors are no longer required to mitigate design-basis
accidents and, therefore, the hydrogen monitors do not meet the
definition of a safety-related component as defined in 10 CFR 50.2. RG
1.97 recommends classifying the hydrogen monitors as Category 1. RG
1.97 Category 1, is intended for key variables that most directly
indicate the accomplishment of a safety function for design-basis
accident events and, therefore, are items usually addressed within TS.
As part of the rulemaking to revise 10 CFR 50.44, the Commission found
that the hydrogen monitors no longer meet the definition of Category 1
in RG 1.97. The Commission concluded that Category 3, as defined in RG
1.97, is an appropriate categorization for the hydrogen monitors
because the monitors are required to diagnose the course of beyond
design-basis accidents. Hydrogen monitoring is not the primary means of
indicating a significant abnormal degradation of the reactor coolant
pressure boundary. Section 4 of Attachment 2 to SECY-00-0198, ``Status
Report on Study of Risk-Informed Changes to the Technical Requirements
of 10 CFR Part 50 (Option 3) and Recommendations on Risk-Informed
Changes to 10 CFR 50.44 (Combustible Gas Control),'' found that the
hydrogen monitors were not risk-significant. Therefore, the staff finds
that hydrogen monitoring equipment requirements no longer meet any of
the four criteria in 10 CFR 50.36(c)(2)(ii) for retention in TS and,
therefore, may be relocated to other licensee-controlled documents.
[Note: The elimination of Post-Accident Sampling System
requirements from some plant-specific TS (and associated CLIIP
notices) indicated that during the early phases of an accident,
safety-grade hydrogen monitors provide an adequate capability for
monitoring containment hydrogen concentration. The staff has
subsequently concluded that Category 3 hydrogen monitors also
provide an adequate capability for monitoring containment hydrogen
concentration during the early phases of an accident.]
However, because the monitors are required to diagnose the course
of beyond design-basis accidents, each licensee should verify that it
has, and make a regulatory commitment to maintain, a hydrogen
monitoring system capable of diagnosing beyond design-basis accidents.
3.3 Oxygen Monitoring Equipment (for applicable plants)
STS and plant-specific TS currently require oxygen monitoring to
verify the status of the inert containment. Combustible gases produced
by beyond design-basis accidents involving both fuel-cladding oxidation
and core-concrete interaction would be risk-significant for plants with
Mark I and II containments if not for the inerted containment
atmospheres. If an inerted containment was to become de-inerted during
a beyond design-basis accident, then other severe accident management
strategies, such as purging and venting, would need to be considered.
The oxygen monitors are needed to implement these severe accident
management strategies. Oxygen concentration also appears extensively in
the emergency procedure guidelines/severe accident guidelines of plants
with inerted containment atmospheres.
With the elimination of the design-basis LOCA hydrogen release, the
oxygen monitors are no longer required to mitigate design-basis
accidents and, therefore, the oxygen monitors do not meet the
definition of a safety-related component as defined in 10 CFR 50.2. RG
1.97 recommends that, for inerted containment plants, the oxygen
monitors be Category 1 which is intended for key variables that most
directly indicate the accomplishment of a safety function for design-
basis accident events. As part of the rulemaking to revise 10 CFR
50.44, the Commission found that Category 2, as defined in RG 1.97, is
an appropriate categorization for the oxygen monitors, because the
monitors are required to verify the status of the inert containment.
Oxygen monitoring is not the primary means of indicating a significant
abnormal degradation of the reactor coolant pressure boundary. Oxygen
monitors have not been shown by a probabilistic risk assessment to be
risk-significant. Therefore, the staff finds that oxygen monitoring
equipment requirements no longer meet any of the four criteria in 10
CFR 50.36(c)(2)(ii) for retention in TS and, therefore, may be
relocated to other licensee-controlled documents.
However, for plant designs with an inerted containment, each
licensee should verify that it has, and make a regulatory commitment to
maintain, an oxygen monitoring system capable of verifying the status
of the inert containment. In addition, separate requirements for
primary containment oxygen concentration will be retained in
[[Page 55420]]
TS for plant designs with an inerted containment. The basis for
retention of this requirement in TS is that it meets Criterion 2 of 10
CFR 50.36(c)(2)(ii) in that it is a process variable, design feature,
or operating restriction that is an initial condition of a design basis
accident or transient analysis that either assumes the failure of or
presents a challenge to the integrity of a fission product barrier.
This is based on the fact that calculations typically included in
Chapter 6 of Updated Final Safety Analysis Reports assume that the
primary containment is inerted, that is, oxygen concentration < 4.0
volume percent, when a design basis LOCA occurs.
[The deletion of the requirements for the hydrogen recombiner and
hydrogen [and oxygen] monitors resulted in numbering and formatting
changes to other TS, which were otherwise unaffected by this proposed
amendment. The NRC staff has confirmed that the related changes are
appropriate and do not affect the technical requirements.]
4.0 Verifications and Commitments
As requested by the staff in the notice of availability for this TS
improvement, the licensee has addressed the following plant-specific
verifications and commitments.
4.1 Each licensee should verify that it has, and make a regulatory
commitment to maintain, a hydrogen monitoring system capable of
diagnosing beyond design-basis accidents.
The licensee has verified that it has a hydrogen monitoring system
capable of diagnosing beyond design-basis accidents. The licensee has
committed to maintain the hydrogen monitors within its [specified
document or program]. The licensee has [implemented this commitment or
will implement this commitment by (specific date)].
4.2 For plant designs with an inerted containment, each licensee
should verify that it has, and make a regulatory commitment to
maintain, an oxygen monitoring system capable of verifying the status
of the inert containment. (for applicable plants)
The licensee has verified that it has an oxygen monitoring system
capable of verifying the status of the inert containment. The licensee
has committed to maintain the oxygen monitors within its [specified
document or program]. The licensee has [implemented this commitment or
will implement this commitment by (specific date)].
The NRC staff finds that reasonable controls for the implementation
and for subsequent evaluation of proposed changes pertaining to the
above regulatory commitments are provided by the licensee's
administrative processes, including its commitment management program.
Should the licensee choose to incorporate a regulatory commitment into
the emergency plan, final safety analysis report, or other document
with established regulatory controls, the associated regulations would
define the appropriate change-control and reporting requirements. The
staff has determined that the commitments do not warrant the creation
of regulatory requirements which would require prior NRC approval of
subsequent changes. The NRC staff has agreed that NEI 99-04, Revision
0, ``Guidelines for Managing NRC Commitment Changes,'' provides
reasonable guidance for the control of regulatory commitments made to
the NRC staff. (See Regulatory Issue Summary 2000-17, ``Managing
Regulatory Commitments Made by Power Reactor Licensees to the NRC
Staff,'' dated September 21, 2000.) The commitments should be
controlled in accordance with the industry guidance or comparable
criteria employed by a specific licensee. The staff may choose to
verify the implementation and maintenance of these commitments in a
future inspection or audit.
5.0 State Consultation
In accordance with the Commission's regulations, the [ State ]
State official was notified of the proposed issuance of the amendment.
The State official had [(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 and changes surveillance
requirements. 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 (FR
[citation and date]). 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
amendments will not be inimical to the common defense and security or
to the health and safety of the public.
Model No Significant Hazards Consideration Determination
Description of Amendment Request: The proposed amendment deletes
requirements from the Technical Specifications to maintain hydrogen
recombiners and hydrogen [and oxygen] monitors. Licensees were
generally required to implement upgrades as described in NUREG-0737,
``Clarification of TMI [Three Mile Island] Action Plan Requirements,''
and Regulatory Guide (RG) 1.97, ``Instrumentation for Light-Water-
Cooled Nuclear Power Plants to Assess Plant and Environs Conditions
During and Following an Accident.'' Implementation of these upgrades
was an outcome of the lessons learned from the accident that occurred
at TMI, Unit 2. Requirements related to combustible gas control were
imposed by Order for many facilities and were added to or included in
the technical specifications (TS) for nuclear power reactors currently
licensed to operate. The revised 10 CFR 50.44, ``Standards for
Combustible Gas Control System in Light-Water-Cooled Power Reactors,''
eliminated the requirements for hydrogen recombiners and relaxed safety
classifications and licensee commitments to certain design and
qualification criteria for hydrogen and oxygen monitors.
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:
Criterion 1--The Proposed Change Does Not Involve a Significant
Increase in the Probability or Consequences of an Accident Previously
Evaluated
The revised 10 CFR 50.44 no longer defines a design-basis loss-of-
coolant
[[Page 55421]]
accident (LOCA) hydrogen release, and eliminates requirements for
hydrogen control systems to mitigate such a release. The installation
of hydrogen recombiners and/or vent and purge systems required by 10
CFR 50.44(b)(3) was intended to address the limited quantity and rate
of hydrogen generation that was postulated from a design-basis LOCA.
The Commission has found that this hydrogen release is not risk-
significant because the design-basis LOCA hydrogen release does not
contribute to the conditional probability of a large release up to
approximately 24 hours after the onset of core damage. In addition,
these systems were ineffective at mitigating hydrogen releases from
risk-significant accident sequences that could threaten containment
integrity.
With the elimination of the design-basis LOCA hydrogen release,
hydrogen [and oxygen] monitors are no longer required to mitigate
design-basis accidents and, therefore, the hydrogen monitors do not
meet the definition of a safety-related component as defined in 10 CFR
50.2. RG 1.97 Category 1, is intended for key variables that most
directly indicate the accomplishment of a safety function for design-
basis accident events. The hydrogen [and oxygen] monitors no longer
meet the definition of Category 1 in RG 1.97. As part of the rulemaking
to revise 10 CFR 50.44 the Commission found that Category 3, as defined
in RG 1.97, is an appropriate categorization for the hydrogen monitors
because the monitors are required to diagnose the course of beyond
design-basis accidents. [Also, as part of the rulemaking to revise 10
CFR 50.44, the Commission found that Category 2, as defined in RG 1.97,
is an appropriate categorization for the oxygen monitors, because the
monitors are required to verify the status of the inert containment.]
The regulatory requirements for the hydrogen [and oxygen] monitors
can be relaxed without degrading the plant emergency response. The
emergency response, in this sense, refers to the methodologies used in
ascertaining the condition of the reactor core, mitigating the
consequences of an accident, assessing and projecting offsite releases
of radioactivity, and establishing protective action recommendations to
be communicated to offsite authorities. Classification of the hydrogen
monitors as Category 3, [classification of the oxygen monitors as
Category 2] and removal of the hydrogen [and oxygen] monitors from TS
will not prevent an accident management strategy through the use of the
SAMGs, the emergency plan (EP), the emergency operating procedures
(EOP), and site survey monitoring that support modification of
emergency plan protective action recommendations (PARs).
Therefore, the elimination of the hydrogen recombiner requirements
and relaxation of the hydrogen [and oxygen] monitor requirements,
including removal of these requirements from TS, does not involve a
significant increase in the probability or the consequences of any
accident previously evaluated.
Criterion 2--The Proposed Change Does Not Create the Possibility of a
New or Different Kind of Accident From Any Previously Evaluated
The elimination of the hydrogen recombiner requirements and
relaxation of the hydrogen [and oxygen] monitor requirements, including
removal of these requirements from TS, will not result in any failure
mode not previously analyzed. The hydrogen recombiner and hydrogen [and
oxygen] monitor equipment was intended to mitigate a design-basis
hydrogen release. The hydrogen recombiner and hydrogen [and oxygen]
monitor equipment are not considered accident precursors, nor does
their existence or elimination have any adverse impact on the pre-
accident state of the reactor core or post accident confinement of
radionuclides within the containment building.
Therefore, this change does not create the possibility of a new or
different kind of accident from any previously evaluated.
Criterion 3--The Proposed Change Does Not Involve a Significant
Reduction in the Margin of Safety
The elimination of the hydrogen recombiner requirements and
relaxation of the hydrogen [and oxygen] monitor requirements, including
removal of these requirements from TS, in light of existing plant
equipment, instrumentation, procedures, and programs that provide
effective mitigation of and recovery from reactor accidents, results in
a neutral impact to the margin of safety.
The installation of hydrogen recombiners and/or vent and purge
systems required by 10 CFR 50.44(b)(3) was intended to address the
limited quantity and rate of hydrogen generation that was postulated
from a design-basis LOCA. The Commission has found that this hydrogen
release is not risk-significant because the design-basis LOCA hydrogen
release does not contribute to the conditional probability of a large
release up to approximately 24 hours after the onset of core damage.
Category 3 hydrogen monitors are adequate to provide rapid
assessment of current reactor core conditions and the direction of
degradation while effectively responding to the event in order to
mitigate the consequences of the accident. The intent of the
requirements established as a result of the TMI, Unit 2 accident can be
adequately met without reliance on safety-related hydrogen monitors.
[Category 2 oxygen monitors are adequate to verify the status of an
inerted containment.]
Therefore, this change does not involve a significant reduction in
the margin of safety. [The intent of the requirements established as a
result of the TMI, Unit 2 accident can be adequately met without
reliance on safety-related oxygen monitors.] Removal of hydrogen [and
oxygen] monitoring from TS will not result in a significant reduction
in their functionality, reliability, and availability.
Based upon the reasoning presented above and the previous
discussion of the amendment request, the requested change does not
involve a significant hazards consideration.
Dated at Rockville, Maryland, this 12th day of September 2003.
For the Nuclear Regulatory Commission.
Herbert N. Berkow,
Director, Project Directorate IV, Division of Licensing Project
Management, Office of Nuclear Reactor Regulation.
[FR Doc. 03-24204 Filed 9-24-03; 8:45 am]
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