[Federal Register Volume 80, Number 14 (Thursday, January 22, 2015)]
[Notices]
[Pages 3260-3264]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2015-01032]
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NUCLEAR REGULATORY COMMISSION
[Docket No. 50-368; NRC-2015-0008]
Entergy Operations, Inc., Arkansas Nuclear One, Unit 2
AGENCY: Nuclear Regulatory Commission.
ACTION: Exemption; issuance.
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SUMMARY: The U.S. Nuclear Regulatory Commission (NRC) is issuing an
exemption in response to a January 21, 2014, request from Entergy
Operations, Inc. (Entergy or the licensee), from certain requirements
to perform Type B testing (seal pressure test) of the containment
emergency escape air lock doors. This exemption would permit the
licensee to perform a door seal contact verification check in lieu of
the currently required seal pressure test.
DATES: January 22, 2015.
ADDRESSES: Please refer to Docket ID NRC-2015-0008 when contacting the
NRC about the availability of information regarding this document. You
may obtain publicly-available information related to this document
using any of the following methods:
Federal Rulemaking Web site: Go to http://www.regulations.gov and search for Docket ID NRC-2015-0008. Address
questions about NRC dockets to Carol Gallagher; telephone: 301-287-
3422; email: [email protected]. For technical questions, contact
the individual listed in the FOR FURTHER INFORMATION CONTACT section of
this document.
NRC's Agencywide Documents Access and Management System
(ADAMS): You may obtain publicly-available documents online in the
ADAMS Public Documents collection at http://www.nrc.gov/reading-rm/adams.html. To begin the search, select ``ADAMS Public Documents'' and
then select ``Begin Web-based ADAMS Search.'' For problems with ADAMS,
please contact the NRC's Public Document Room (PDR) reference staff at
1-800-397-4209, 301-415-4737, or by email to [email protected]. The
ADAMS accession number for each document referenced in this document
(if that document is available in ADAMS) is provided the first time
that a document is referenced.
NRC's PDR: You may examine and purchase copies of public
documents at the NRC's PDR, Room O1-F21, One White Flint North, 11555
Rockville Pike, Rockville, Maryland 20852.
FOR FURTHER INFORMATION CONTACT: Andrea George, Office of Nuclear
Reactor Regulation, U.S. Nuclear Regulatory Commission, Washington DC
20555-0001; telephone: 301-415-1081, email: [email protected].
SUPPLEMENTARY INFORMATION:
I. Background
Entergy is the holder of renewed Facility Operating License No.
NPF-6, which authorizes operation of Arkansas Nuclear One (ANO), Unit
2. The license provides, among other things, that the facility is
subject to all rules, regulations, and orders of the NRC now or
hereafter in effect.
The ANO facility consists of two pressurized-water reactors, Units
1 and 2, located in Pope County, Arkansas.
II. Request/Action
Pursuant to Sec. 50.12 of Title 10 of the Code of Federal
Regulations (10 CFR), ``Specific exemptions,'' by letter dated January
21, 2014 (ADAMS Accession No. ML14021A085), as supplemented by letters
dated March 17 and September 24, 2014 (ADAMS Accession Nos. ML14077A139
and ML14268A317, respectively), the licensee requested an exemption
from certain requirements of 10 CFR part 50, Appendix J, ``Primary
Reactor Containment Leakage Testing for Water-Cooled Power Reactors.''
Specifically, the licensee requested an exemption from Option B,
Section III.B, Type B testing (seal pressure test) of the ANO, Unit 2,
containment emergency escape air lock doors. This exemption would
permit the licensee to perform a door seal contact verification check
in lieu of the currently required seal pressure test.
Section III.B, Option B, Appendix J, 10 CFR part 50, defines Type B
tests as pneumatic tests to detect and measure local leakage rates
across pressure retaining, leakage-limiting boundaries, which include
containment emergency escape air lock door seals. Section III.B, Option
B, Appendix J, 10 CFR part 50, also states that these boundaries, such
as containment emergency escape air locks, must be pneumatically tested
(1) prior to initial criticality, and (2) periodically thereafter at
intervals based on the safety significance and historical performance
of each boundary and isolation valve to ensure the integrity of the
overall containment system as a barrier to fission product release.
The licensee stated that the exemption request is necessary due to
the design characteristics of the ANO, Unit 2, containment emergency
escape air lock doors, in that the door sealing capability relies, in
part, on rising containment pressure to provide sufficient closing
force to produce an effective seal. In order to perform between-the-
seals testing for the doors in the absence of containment pressure, a
strongback must be installed to simulate this sealing force.
III. Discussion
Pursuant to 10 CFR 50.12, the Commission may, upon application by
any interested person or upon its own initiative, grant exemptions from
the requirements of 10 CFR part 50 when: (1) The exemptions are
authorized by law, will not present an undue risk to public health or
safety, and are consistent with the common defense and security; and
(2) when special circumstances are present. Under 10 CFR
50.12(a)(2)(ii), special
[[Page 3261]]
circumstances include, among other things, when application of the
specific regulation in the particular circumstance would not serve, or
is not necessary to achieve, the underlying purpose of the rule.
A. Special Circumstances
Special circumstances, in accordance with 10 CFR 50.12(a)(2)(ii),
are present whenever application of the regulation in the particular
circumstances is not necessary to achieve the underlying purpose of the
rule. The underlying purpose of Type B testing in Section III.B, Option
B, Appendix J, 10 CFR part 50, is to verify containment integrity as a
fission product barrier to provide reasonable assurance of public
health and safety in the event of a loss-of-coolant accident. The
evaluations described in the following sections of this exemption show
that the underlying purpose of the regulations is met by the proposed
seal contact check for the ANO, Unit 2, containment emergency escape
airlock doors. Specifically, due to the design of the doors at ANO,
Unit 2, the currently required between-the-seals testing (for the
annulus between the inner and outer emergency air lock doors), if done
without the strongback installed, is unable to hold pressure at or near
the Technical Specification (TS) required pressure, and so meaningful
between-the-seals testing is not possible without installing the
strongback or exerting significant closing torque to the door closure
mechanism. The seal contact check, where chalk is applied to the air
lock door seal face, the door is cycled open and closed, and the chalk
outline left is representative of the door seal bead mating with the
seal. If the chalk pattern does not show adequate contact, the seals
are adjusted and the seal contact test is reperformed until a 360-
degree seal results. The seal contact check and seal adjustments (if
necessary), the practices for which have been incorporated into ANO,
Unit 2, maintenance procedures, ensure that the containment emergency
air lock doors are sealing properly and that seal integrity of the
doors is maintained. The underlying purpose of Type B testing in
Section III.B, Option B, Appendix J, 10 CFR part 50, is achieved
through application of the seal contact check for the air lock doors.
Therefore, the special circumstances required by 10 CFR 50.12(a)(2)(ii)
for the granting of an exemption exist.
B. Authorized by Law
This exemption would allow the use of a seal contact check, in lieu
of a seal pressure test, to verify the seal tightness of the ANO, Unit
2, containment emergency escape air lock doors. As stated above, 10 CFR
50.12 allows the NRC to grant exemptions from the requirements of 10
CFR part 50 provided that special circumstances are present. As
described above, the NRC staff has determined that special
circumstances exist to grant the requested exemption. In addition,
granting the exemption will not result in a violation of the Atomic
Energy Act of 1954, as amended, or the Commission's regulations.
Therefore, the exemption is authorized by law.
C. No Undue Risk to Public Health and Safety
This exemption request is necessary due to the original design of
the containment emergency escape air lock at ANO, Unit 2. The air lock
consists of a steel cylinder with a circular door at each end, an outer
door and inner door, with the inner door being directly in contact with
the interior of the containment building. Both of the air lock doors
open inward toward the containment building interior, and so, during
between-the-seals pressure testing (between the two air lock doors),
the increasing pressure tends to more tightly seat the outer air lock
door and push the inner airlock door off of its seat. The licensee
stated that though each air lock door is fitted with two latching pins,
one for the top and one for the bottom, these pins are not designed to
provide enough closing force for meaningful between-the-seals testing
without a strongback installed. During a postulated design basis event,
both air lock doors rely on rising containment building pressure to
provide closing force for a sufficiently tight seal in order to
constitute a fission product boundary.
In its application, the licensee stated that during trial testing,
the annulus between the door seals could not be successfully tested
without the door strongback installed, even at pressures as low as 12
pounds per square inch gauge. This indicates that the leak rates for
between-the-seals testing on the emergency escape air lock doors cannot
meet the acceptance criteria found in Section III.B.1.(c), Appendix J,
10 CFR part 50, without the use of a strongback. The licensee stated
that it has taken efforts to improve the test without the use of a
strongback, and that these efforts have produced conflicting results.
The licensee concluded that a complete change-out of the inner and
outer bulkhead and door assemblies would be required to support
incorporating an ``O'' ring seal design with a 3-pin latching
configuration. Based on vendor information, the ``O'' ring seal design
is superior to the flat seal profile design. Consideration was also
given to a gear reduction design for the opening and closing mechanism.
The licensee stated that while this option would increase sealing
forces, there is insufficient evidence to determine whether such a
modification would ensure future success with respect to between-the-
seals pressure testing.
The licensee stated that in recent years, it has performed
significant maintenance and modification activities on the air lock
doors with onsite vendor support. By letter dated August 11, 2014
(ADAMS Accession No. ML14218A602), the NRC staff submitted a request
for additional information to the licensee regarding whether seal
design, seal material, seal shape, and seal operation conditions had
been evaluated to address the between-the-seals testing difficulties.
In its response dated September 24, 2014, the licensee stated that the
following activities have been completed in recent years regarding the
air locks: (1) Increased door to seal contact by adjusting door
settings, (2) designed a torque amplifying device to assist in opening/
closing the door due to increasing the contact pressures, (3) replaced
door seals every refueling outage, (4) upgraded door locking bolt
compression springs to allow for additional closing forces with
improved ability to open the doors, (5) replaced locking bolt brackets
and pins, and (6) obtained vendor support and expertise to maintain and
adjust the door for optimum performance. The licensee also stated that
the seal material currently in use is an ethylene-propylene-diamine-
monomer, which is the vendor recommended and qualified material. The
seals are a square cross-section shape design formed in a continuous
circle to fit the bulk head frame seal channel. By design of the
channel, the seal shape is limited. In addition, each door is designed
with a ``nose/sealing bar'' that provides a continuous protrusion into
the flat-faced seal for improved sealing contact. These features
prevent seal design changes without extensive changes to the design and
hardware of the hatch.
In its application, the licensee indicated that the vendor has
clearly stated that the ANO, Unit 2, air lock design does not support
testing without the use of a strongback and, to meet leak rate limits,
the airlock's latching mechanism must generate a high latch contact
such that it will maintain a residual compressive load on the gasket
greater than the unseating effect produced by the test pressure.
[[Page 3262]]
Adjustment and/or modification of the latch in this manner defeats the
purpose of the emergency escape air lock since excessive human force
would be required to open the air lock door in an emergency situation.
The licensee provided information regarding two events where personnel
or equipment difficulties precluded the air lock doors from being
opened or opening as designed. In 2008, after an individual became
trapped in the air lock due to being unable to open the door, the
licensee installed a torque amplifying device to assist personnel in
door opening/closing. In 2012, the air lock outer door required
mechanical agitation to open, and it was noted that the 3/4-inch
stainless steel latch pins were bent. Based on efforts to date, the
licensee has concluded that attempting to apply excessive closing
torque to the door necessary to overcome the original design
characteristics is inappropriate.
The licensee has investigated the potential of substantial
modifications to the air lock doors in order to meet the current seal
pressure test requirements and the Occupational Safety and Health
Administration's requirements. Beyond the many components previously
replaced, along with spring upgrades to help alleviate the excessive
force now needed to operate the doors, the licensee has determined
complete door replacement (retrofit) would be necessary to resolve the
aforementioned issues and have the ability to perform a meaningful
between-the-seals pressure test. The licensee stated that vendor
proposals for door replacement reflect an extremely high estimated
cost, without any guarantee that such a modification would resolve the
issue of air lock seal pressure testing. The cost of pursuing such a
modification is unwarranted because no appreciable increase in nuclear
or public safety would be realized.
In its application, the licensee stated that past TS surveillance
testing for the emergency escape air lock has shown that testing with
strongbacks in place is successful; however, the pressure applied by
the strongbacks, or the pressure applied to the outer door during the
overall air lock pressure test, can cause door seals to take a set that
reflects the shape of the seal grooves. With strongbacks installed or
test pressure applied to the air lock barrel, the male portion of the
door seal (the seal bead) can be pressed into the seal. The seal will
remain in this compressed condition for the entire test period, causing
the seal to take a set in the seal groove of the air lock bulkhead.
After completion of an overall air lock barrel pressure test, both
doors must be opened to verify proper seal contact with the door seal
bead in order to ensure that the seals rebound to the pre-test
condition. During the seal contact check, a seal adjustment may be
required after testing because the force of the strongbacks on a given
door and/or the force due to the air lock barrel test pressure on the
outer door can draw the seal bead on the doors further into the seal
groove than what would occur under normal door closure forces.
The seal contact check consists of applying chalk or other viable
medium on the seal face and then closing and reopening the emergency
escape air lock door. This will result in a pattern in the chalk (or
other medium) that is representative of the door seal bead mating with
the seal. If the chalk (or other medium) pattern does not show adequate
contact, the seals are adjusted in the area of the gap. Following
adjustment, the licensee performs a final seal contact check to verify
the integrity of the sealing surface. The practice of verifying
acceptable seal contact following performance of the overall air lock
leak test and the acceptance criteria for this verification have been
incorporated into the ANO, Unit 2, maintenance procedures.
The performance of the door seal contact check has led to the
successful completion of subsequent emergency escape air lock full
pressure tests since the procedural practice began. In a request for
additional information dated August 11, 2014 (ADAMS Accession No.
ML14218A602), the NRC staff requested that the licensee provide test
results to show the effectiveness of the seal contact check. In its
supplement dated September 24, 2014, the licensee provided the test
results following seal contact checks for refueling outages from 2008
(2R19) to 2014 (2R23). In its supplement, the licensee stated that the
results indicate that performance of the seal contact check is
instrumental in the successful completion of subsequent leak testing.
In its application, the licensee noted that acceptance criteria for
containment building integrated leak rate testing (ILRT) has been met
for each ILRT since initial plant startup, indicating that the
emergency escape airlock door seals are meeting their design function
when exposed to pressure in the correct (accident) direction.
As an alternative to the between-the-seals pressure test of the
emergency escape air lock required by Section III.B, Option B, Appendix
J, 10 CFR part 50, the licensee has proposed a final door seal contact
verification. This seal performance verification is completed following
the full pressure airlock test, after the removal of the inner door
strongback, and just prior to final closure of the airlock doors. The
requested exemption would not affect compliance with the requirement to
perform a full pressure emergency escape airlock test each refueling
outage. Based on these results and information provided by the
licensee, the NRC staff concludes that the containment building
emergency airlock doors at ANO, Unit 2, function as designed using
current methods of testing and maintenance, including seal contact
checks. The NRC staff further concludes that the seal contact checks
performed on the emergency escape airlock door seals ensure that the
doors are sealing properly and will perform their design function to
limit radiological release in the case of a postulated accident.
Therefore, the NRC staff determined that the between-the-seals testing
required by Section III.B, Option B, Appendix J, 10 CFR part 50, is not
necessary to achieve the underlying purpose of the rule for the
emergency escape air lock doors, given their current design. Since the
above evaluations demonstrate that the underlying purpose of the rule
will be met with the seal contact check, the NRC staff concludes that
there is no undue risk to the public health and safety.
D. Consistent With the Common Defense and Security
The licensee's exemption request is to utilize an alternative to
the Type B containment emergency escape air lock door seal pressure
testing requirement in Section III.B, Option B, Appendix J, 10 CFR part
50. This exemption request is not related to, and does not impact any
security issues at ANO, Unit 2. Therefore, the NRC staff determined
that this exemption does not impact, and is consistent with, the common
defense and security.
E. Environmental Considerations
The NRC staff determined that the exemption discussed herein meets
the eligibility criteria for the categorical exclusion set forth in 10
CFR 51.22(c)(9) because it is related to a requirement concerning the
installation or use of a facility component located within the
restricted area, as defined in 10 CFR part 20, and issuance of this
exemption involves no significant hazards consideration, no significant
change in the types or a significant increase in the amounts of any
effluents that may be released offsite, and no significant increase in
individual or cumulative occupational radiation exposure. Therefore, in
accordance with 10 CFR
[[Page 3263]]
51.22(b), no environmental impact statement or environmental assessment
need be prepared in connection with the NRC's consideration of this
exemption request. The basis for the NRC staff's determination is
discussed as follows with an evaluation against each of the
requirements in 10 CFR 51.22(c)(9)(i)-(iii).
Requirements in 10 CFR 51.22(c)(9)(i)
The NRC staff evaluated whether the exemption involves no
significant hazards consideration using the standards described in 10
CFR 50.92(c), as presented below:
1. Does the proposed exemption involve a significant increase in
the probability or consequences of an accident previously evaluated?
Response: No.
The proposed change would permit emergency escape air lock door
seal leak integrity testing to be performed by a seal contact check in
place of the between-the-seals pressure test. The seal contact check
will be performed following emergency escape air lock door opening,
overall full pressure test of the emergency escape air lock, or air
lock door seal contact adjustments. The seal contact test method will
result in a continuation of the established practice at ANO, Unit 2,
which has provided a high degree of confidence in door seal
performance. The performance of the door seal contact test method at
ANO, Unit 2, has led to the successful completion of subsequent
emergency escape air lock full pressure tests since the procedural
practice began. Furthermore, the acceptance criteria for containment
building ILRT has been met for each ILRT since initial plant startup,
indicating that the air lock door seals are meeting their design
function when exposed to pressure in the correct (accident) direction.
At Palisades Nuclear Plant, emergency escape air lock door seals which
have been inspected in accordance with the proposed methodology have
passed subsequent full pressure emergency escape air lock leakage tests
and have not interfered with successful Containment Building ILRT.
Since the proposed methodology can be used to successfully verify
door seal condition and contact, the use of this methodology for
testing will not cause an increase in the probability of a leaking
emergency escape air lock door seal going undetected. The combination
of the door seal contact check and the overall full pressure testing of
the emergency escape air lock will provide high confidence of the air
lock performing its design function under accident conditions.
Therefore, this change does not involve a significant increase in
the probability or consequences of an accident previously evaluated.
2. Does the proposed exemption create the possibility of a new or
different kind of accident from any accident previously evaluated?
Response: No.
The proposed change is associated exclusively with testing of
features related to Containment Building integrity. The change affects
only the testing methodology of the emergency escape air lock door
seals. The proposed testing method does not result in any physical
alterations to the plant configuration, no new structure, system, or
component (SSC) is added, no SSC interfaces are modified, and no
changes to any design function of an SSC or the methods of SSC
operation are being made. As the proposed change would not change the
design, configuration, or operation of the plant, the change would not
cause the Containment Leakage Rate Testing Program to become an
accident initiator.
Therefore, this change does not create the possibility of a new or
different kind of accident from an accident previously evaluated.
3. Does the proposed exemption involve a significant reduction in a
margin of safety?
Response: No.
The proposed change is associated exclusively with testing of
features related to Containment Building integrity. The change affects
only the testing methodology of the emergency escape air lock door
seals. The change is unrelated to an initiator of any accident
previously evaluated. The proposed application of a door seal contact
check in lieu of a between-the-seals pressure test along with
continuation of the overall full pressure test of the emergency escape
air lock will continue to provide high confidence that the Containment
Building leakage rate criteria for the emergency escape air lock will
not exceed the maximum allowable leakage rates defined in the TSs or
assumed in the accident analysis.
Therefore, this change does not involve a significant reduction in
a margin safety.
Based on the above evaluation of the standards set forth in 10 CFR
50.92(c), the NRC staff concludes that the proposed exemption involves
no significant hazards consideration. Accordingly, the requirements of
10 CFR 51.22(c)(9)(i) are met.
Requirements in 10 CFR 51.22(c)(9)(ii)
The proposed exemption would allow containment emergency escape air
lock door seal pressure testing to be performed by a seal contact
verification test. This change only affects the leakage integrity
testing methodology of the door seals, and does not change the
frequency at which the testing must be performed. The proposed testing
methodology serves the same purpose as the pressure testing required by
regulations. Therefore, the proposed alternative testing methodology
will not significantly change the types of effluents that may be
released offsite, or significantly increase the amount of effluents
that may be released offsite. Therefore, the requirements of 10 CFR
51.22(c)(9)(ii) are met.
Requirements in 10 CFR 51.22(c)(9)(iii)
The proposed exemption would allow containment emergency escape air
lock door seal pressure testing to be performed by a seal contact
verification test. This change only affects the leakage integrity
testing methodology of the door seals and has no impact on, or change
to, fuel or core design. Therefore, the proposed alternative testing
methodology will not significantly increase individual occupational
radiation exposure or significantly increase cumulative occupational
radiation exposure. Therefore, the requirements of 10 CFR
51.22(c)(9)(iii) are met.
Conclusion
Based on the above, the NRC staff concludes that the proposed
exemption meets the eligibility criteria for the categorical exclusion
set forth in 10 CFR 51.22(c)(9). Therefore, in accordance with 10 CFR
51.22(b), no environmental impact statement or environmental assessment
need be prepared in connection with the NRC's issuance of this
exemption.
IV. Conclusions
Accordingly, the Commission has determined that, pursuant to 10 CFR
50.12(a), the exemption is authorized by law, will not present an undue
risk to the public health and safety, and is consistent with the common
defense and security. Also, special circumstances are present.
Therefore, the Commission hereby grants the licensee an exemption from
10 CFR part 50, Appendix J, Option B, Section III.B, Type B testing
(seal pressure test) to perform a seal contact verification test, in
lieu of seal pressure testing, for the ANO, Unit 2, emergency escape
air lock doors.
[[Page 3264]]
This exemption is effective upon issuance.
Dated at Rockville, Maryland, this 12th day of January 2015.
For the Nuclear Regulatory Commission.
Michele G. Evans,
Director, Division of Operating Reactor Licensing, Office of Nuclear
Reactor Regulation.
[FR Doc. 2015-01032 Filed 1-21-15; 8:45 am]
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