[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 
1.0L<INF>a. 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 2L<INF>a; in one case the as-found 
leakage was less than 3L<INF>a; one case approached 10L<INF>a; and in 
one case the leakage was found to be approximately 21L<INF>a. 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 L<INF>a (approximately 200L<INF>a, 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]
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