[Federal Register Volume 59, Number 53 (Friday, March 18, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-6408]
[[Page Unknown]]
[Federal Register: March 18, 1994]
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NUCLEAR REGULATORY COMMISSION
[Docket No. 50-328]
Tennessee Valley Authority (Sequoyah Nuclear Plant, Unit 2);
Exemption
I
The Tennessee Valley Authority (TVA) is the holder of Facility
Operating License No. DPR-79, which authorizes operation of the
Sequoyah Nuclear Plant, Unit 2 (the facility, Unit 2). The license
provides, among other things, that the facility is subject to all
rules, regulations, and orders of the Nuclear Regulatory Commission
(the Commission) now or hereafter in effect.
The facility consists of a pressurized water reactor located on
TVA's Sequoyah site in Hamilton County, Tennessee.
II
Sections III.D.2(a) and III.D.3 of appendix J to 10 CFR part 50
require that Types B and C local leak rate tests be performed during
reactor shutdown for refueling, or other convenient intervals, but in
no case at intervals greater than 2 years.
On March 15, 1992, SQN Unit 2 started the Cycle 5 refueling outage.
All Type B and Type C local leak rate tests were performed during the
outage and the unit was returned to service on May 17, 1992. Between
March 1, 1993, and October 19, 1993, Unit 2 was shut down. Several
forced outages also occurred following restart. Due to the accumulated
length of time the Unit was shut down, TVA has postponed the start of
the Unit 2 Cycle 6 refueling outage from September 1993 to July 1994.
As a result, the expiration of the 2-year time interval for some Type B
and Type C tests occurs before the outage starts. To perform the tests
in accordance with the requirement would force the unit to shut down in
March 1994. To prevent this, the licensee has requested an exemption
that would allow a one-time deferment of the Appendix J 2-year interval
requirement from March 15, 1994, until the shutdown for the refueling
outage starting in July 1994, a total of approximately 4 months.
The extension would affect 39 bellows penetrations, 47 electrical
penetrations, 196 isolation valves, 11 flanges, 1 hydrogen analyzer,
and 10 residual heat removal system spray header valves. These valves
and components, which represent approximately 88 percent of the total
leak rate test program, are considered by the licensee to be leak tight
and in good condition, which was verified by the leak rate tests
performed during the Cycle 5 refueling outage. Based on the present
containment leak rate that accounts for less than 8.0 percent of the
applicable limit, the licensee believes that the remaining margin is
sufficient to ensure that any incremental increase in leakage because
of the extension, will not result in unacceptable as-found test
results. Also, based on historical data, the licensee believes that any
incremental increase in leakage from these components because of the
extension would be small. In addition, many of the components were
included in the boundary for the last Type A test that was performed in
April 1992, and have been subjected to improve maintenance practices,
which provide increased assurance that the components will be capable
of performing their intended safety function. The only valves that had
appreciable leakage during both the Unit 2 Cycle 4 and Cycle 5 leak
rate tests were essential raw cooling water system valves, 2-FCV-67-87
and 2-FCV-67-575A (in each case, retests following repairs showed there
was no leakage). To further assure safe plant operation, the licensee
has committed to perform a leak rate test of these valves should the
unit experience a forced outage to Mode 5.
III
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. Special circumstances are
present whenever, according to 10 CFR 50.12(a)(2)(ii), ``Application of
the regulation in the particular circumstances would not serve the
underlying purpose of the rule or is not necessary to achieve the
underlying purpose of the rule * * *.''
The underlying purpose of the requirement to perform Type B and
Type C containment leak rate tests at intervals not to exceed 2 years,
is to ensure that any potential leakage pathways through the
containment boundary are identified within a time span that prevents
significant degradation from continuing or being unknown, and long
enough to allow the tests to be conducted during scheduled refueling
outages. This interval was originally published in appendix J when
refueling cycles were conducted at approximately annual intervals and
has not been changed to reflect 18-month or 2-year operating cycles. It
is not the intent of the regulation to require a plant shutdown solely
for the purpose of conducting the periodic leak rate tests. Based on
historical data at SQN, any incremental increase in leakage because of
the extension would be small. Improved maintenance practices
implemented during the Unit 2 Cycle 5 outage and improved testing
techniques of containment isolation valves to detect any degraded
performance indications, provide increased assurance that these
components will perform their safety function. In addition, on the
average, as-left leak rates are less than 25 percent of the established
reference leak rates. Therefore, since the maximum extension is
relatively short (4 months) compared to the 2-year test interval
requirement, it is unlikely that substantial degradation of the
containment components leading to the failure of the containment to
perform its safety function would occur. As a result, the application
of the regulation in the particular circumstances is not necessary to
achieve the underlying purpose of the rule.
IV
For the foregoing reasons, the NRC staff has concluded that the
licensee's proposed increase of the 2-year time interval for performing
Type B and Type C Containment Leak Rate Tests until the Cycle 6
refueling outage will not present an undue risk to public health and
safety and is consistent with the common defense and security. The NRC
staff has determined that there are special circumstances present, as
specified in 10 CFR 50.12(a)(2), such that application of 10 CFR part
50, appendix J, sections III.D.2(a) and III.D.3 are not necessary in
order to achieve the underlying purpose of this regulation.
Accordingly, the Commission has determined that, pursuant to 10 CFR
50.12(a), an exemption is authorized by law, will not endanger life or
property or common defense and security, and is, otherwise, in the
public interest. Therefore, the Commission hereby grants the Tennessee
Valley Authority exemption from the requirements of Sections III.D.2(a)
and III.D.3 of appendix J to 10 CFR part 50 as requested in the
submittal.
Pursuant to 10 CFR 51.32, the Commission has determined that the
granting of this exemption will not result in any significant adverse
environmental impact (59 FR 11812).
This exemption is effective upon issuance.
Dated at Rockville, Maryland this 14th day of March, 1994.
For the Nuclear Regulatory Commission.
Steven A. Varga,
Director, Division of Reactor Projects--I/II, Office of Nuclear Reactor
Regulation.
[FR Doc. 94-6408 Filed 3-17-94; 8:45 am]
BILLING CODE 7590-01-M
