[Federal Register Volume 60, Number 69 (Tuesday, April 11, 1995)]
[Notices]
[Pages 18432-18433]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-8847]
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NUCLEAR REGULATORY COMMISSION
[Docket No. 50-483]
Union Electric Company (Callaway Plant, Unit 1)
Exemption
I.
Union Electric Company (UE or the licensee) is the holder of
Facility Operating License No. NPF-30, which authorizes operation of
Callaway Plant, Unit 1 (the facility), at a rated power level not in
excess of 3565 megawatts thermal. The facility is a pressurized water
reactor located at the licensee's site in Callaway County, Missouri.
The license provides among other things, that it is subject to all
rules, regulations, and Orders of the U.S. Nuclear Regulatory
Commission (the Commission or NRC) now or hereafter in effect.
II.
Section III.D.1.(a) of Appendix J to 10 CFR Part 50 requires the
performance of three Type A containment integrated leakage rate tests
(CILRTs), at approximately equal intervals during each 10-year service
period. The third test of each set shall be conducted when the plant is
shutdown for the 10-year plant inservice inspection.
III.
By letters dated December 9, 1994, and January 27, 1995, UE
requested relief from the requirement to perform a set of three Type A
tests at approximately equal intervals during each 10-year service
period. The requested exemption would permit an interval extension for
the third Type A test of approximately 18 months (from the currently
scheduled outage, March 1995, until the next planned refueling outage,
September 1996). The exemption request would also permit the third Type
A test of the first 10-year service period not to correspond with the
end of the current American Society of Mechanical Engineers Boiler and
Pressure Vessel Code (ASME Code) 10-year plant inservice inspection
interval.
The licensee's request cites the special circumstances of 10 CFR
50.12, [[Page 18433]] paragraph (a)(2)(ii), as the basis for the
exemption. The underlying purpose of the requirement to perform three
Type A CILRTs, at approximately equal intervals during each 10-year
service period, is to assure that leakage through the primary reactor
containment is detected and does not exceed allowable leakage rate
values. The licensee has stated that the existing Type B and C local
leak rate test (LLRT) programs are not being modified by this request,
and will continue to effectively detect containment leakage caused by
the degradation of active containment isolation components as well as
containment penetrations. It has been the consistent and uniform
experience at Callaway during the three Type A tests conducted from
1984 to date, that any significant containment leakage paths are
detected by the Type B and C testing. The Type A test results have only
been confirmatory of the results of the Type B and C test results.
Therefore, consistent with 10 CFR 50.12, paragraph (a)(2)(ii),
application of the regulation in this particular circumstance would not
serve, nor is it necessary to achieve, the underlying purpose of the
rule.
IV.
Section III.D.1.(a) of Appendix J to 10 CFR Part 50 states that a
set of three Type A leakage rate tests shall be performed at
approximately equal intervals during each 10-year service period.
The licensee proposes an exemption to this section which would
provide an interval extension for the Type A test by approximately 18
months. The Commission has determined that pursuant to 10 CFR
50.12(a)(1) this 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. The Commission further determines that
special circumstances, as provided in 10 CFR 50.12(a)(2)(ii), are
present justifying the exemption; namely, that application of the
regulation in the particular circumstances is not necessary to achieve
the underlying purpose of the rule.
The NRC staff has reviewed the basis and supporting information
provided by the licensee in the exemption request. The NRC staff has
noted that the licensee has a good record of ensuring a leak-tight
containment. All Type A tests were within the acceptance limits. The
first Type A test passed with significant margin. The second Type A
test confirmed leakage previously identified by Type C testing. The
licensee subsequently replaced all containment boundary Essential
Service Water valves with an improved design stainless steel valve.
This replacement improved LLRT results by 84% for the affected
penetrations. The licensee has noted that the results of the Type A
testing have been confirmatory of the Type B and C tests, which are
performed biennially, and will continue to be performed. The NRC staff
considers that these inspections and system enhancements, though
limited in scope, provide an important added level of confidence in the
continued integrity of the containment boundary.
The NRC staff has also made use of a draft staff report, NUREG-
1493, which provides the technical justification for the present
Appendix J rulemaking effort which also includes a 10-year test
interval for Type A tests. The integrated leakage rate test, or Type A
test, measures overall containment leakage. However, operating
experience with all types of containments used in this country
demonstrates that essentially all containment leakage can be detected
by local leakage rate tests (Type B and C). According to results given
in NUREG-1493, out of 180 ILRT reports covering 110 individual reactors
and approximately 770 years of operating history, only about 3% of
leakage that exceeds current requirements is detectable only by CILRTs,
and those few failures were only marginally above prescribed limits.
This study agrees well with previous NRC staff studies which show that
Type B and C testing can detect a very large percentage of containment
leaks. The Callaway experience has also been consistent with this.
The Nuclear Management and Resources Council (NUMARC), now the
Nuclear Energy Institute (NEI), collected and provided the NRC staff
with summaries of data to assist in the Appendix J rulemaking effort.
NUMARC collected results of 144 ILRTs from 33 units; 23 ILRTs exceeded
1.0La. Of these, only nine were not due to Type B or C leakage
penalties. The NEI data also added another perspective. The NEI data
show that in about one-third of the cases exceeding allowable leakage,
the as-found leakage was less than 2La; in one case the as-found
leakage was less than 3La; one case approached 10La; and in
one case the leakage was found to be approximately 21La. For about
half of the failed ILRTs the as-found leakage was not quantified. These
data show that, for those ILRTs for which the leakage was quantified,
the leakage values are small in comparison to the leakage value at
which the risk to the public starts to increase over the value of risk
corresponding to La (approximately 200La, as discussed in
NUREG-1493).
Based on generic and plant specific data, the NRC staff finds the
basis for the licensee's proposed exemption to allow a one-time
exemption to permit a schedular extension of one cycle for the
performance of the Appendix J Type A test to be acceptable.
Pursuant to 10 CFR 51.32, the Commission has determined that
granting this Exemption will not have a significant impact on the
environment (60 FR 15611).
This Exemption is effective upon issuance and shall expire at the
completion of the 1996 refueling outage.
For the Nuclear Regulatory Commission.
Dated at Rockville, Maryland this 4th day of April 1995.
Elinor G. Adensam,
Acting Director, Division of Reactor Projects--III/IV, Office of
Nuclear Reactor Regulation.
[FR Doc. 95-8847 Filed 4-10-95; 8:45 am]
BILLING CODE 7590-01-M
