[Federal Register Volume 60, Number 135 (Friday, July 14, 1995)]
[Notices]
[Pages 36313-36314]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-17294]



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NUCLEAR REGULATORY COMMISSION
[Docket No. 50-315]


In the Matter of: Indiana Michigan Power Company (D.C. Cook 
Nuclear Plant, Unit 1); Exemption

I

    Indiana Michigan Power Company (IMPCo, the licensee) is the holder 
of Facility Operating License No. DPR-58 which authorizes operation of 
the Donald C. Cook Unit 1 Nuclear Plant at steady-state reactor power 
levels not in excess of 3250 megawatts thermal. The Cook 1 facility is 
a pressurized water reactor located at the licensee's site in Berrien 
County, Michigan. 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.

II

    Pursuant to 10 CFR 50.12(a), the NRC may grant exemptions from the 
requirements of the regulations (1) which are authorized by law, will 
not present an undue risk to the public health and safety, and are 
consistent with the common defense and security; and (2) where special 
circumstances are present.
    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 
(ILRTs), at approximately equal intervals during each 10-year service 
period of the primary containment. The third test of each set shall be 
conducted when the plant is shut down for the 10-year inservice 
inspection required by 10 CFR 50.55a.

III

    By letter dated March 17, 1995, IMPCo requested temporary relief 
from the requirement to perform a set of three Type A tests at 
approximately equal intervals during each 10-year service period of the 
primary containment. The requested exemption would permit a one-time 
interval extension of the third Type A test by approximately 20 months 
(from the 1995 refueling outage, currently scheduled to begin in 
September 1995, to the 1997 refueling outage) and would permit the 
third Type A test of the second 10-year inservice inspection period to 
not correspond with the end of the current American Society of 
Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code) 
inservice inspection interval.
    The licensee's request cites the special circumstances of 10 CFR 
50.12, paragraph (a)(2)(ii), as the basis for the exemption. In 
addition, the licensee states that the exemption would eliminate a cost 
of $130,000 for the Type A test which is not necessary to achieve the 
underlying purpose of the rule. 10 CFR Part 50 Appendix J, states that 
the purpose of the Type A, B, and C tests is to assure that leakage 
through the primary containment shall not exceed the allowable leakage 
rate values as specified in the technical specifications or associated 
bases. IMPCo points out that the existing Type B and C testing 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 experience at the D.C. Cook Plant that during the six 
Type A tests conducted from 1974 to date, 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. The testing history, structural capability of the 
containment, and the risk assessment establish that there is 

[[Page 36314]]
significant assurance that the extended interval between Type A tests 
will not adversely impact the leak-tight integrity of the containment 
and that performance of the Type A test is not necessary to meet the 
underlying purpose of Appendix J.

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 a one-time interval extension for the Type A test by 
approximately 20 months. The Commission has determined, for the reasons 
discussed below, 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 underlying purpose of the requirement to perform Type A 
containment leak rate tests at intervals during the 10-year service 
period is to ensure that any potential leakage pathways through the 
containment boundary are identified within a time span that prevents 
significant degradation from continuing. 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.
    The licensee notes that the results of the Type A testing have been 
confirmatory of the Type B and C tests which will continue to be 
performed. The licensee has stated that it will perform the general 
containment inspection although it is required by Appendix J (Section 
V.A.) to be performed only in conjunction with Type A tests. The NRC 
staff considers that these inspections, though limited in scope, 
provide an important added level of confidence in the continued 
integrity of the containment boundary.
    The Cook containment structure consists of a reinforced concrete 
cylindrical structure with a hemispherical dome. The interior of the 
containment has a welded steel liner, with a minimum thickness of \3/8\ 
inch at the dome and wall and \1/4\ inch at the bottom, which is 
attached to the inside face of the concrete shell to ensure a high 
degree of leak tightness.
    The NRC staff has also made use of the information in a draft staff 
report, NUREG-1493, ``Performance-Based Containment Leak-Test 
Program,'' 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 ILRT, 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 Leak 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 5 ILRT failures were found which local leakage 
rate testing could not detect. This is 3% of all failures. 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 
Cook Plant experience has also been consistent with these results.
    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 
1La. Of these, only nine were not 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 leakage was found to be 
approximately 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). 
Therefore, based on these considerations, it is unlikely that an 
extension of one cycle for the performance of the Appendix J, Type A 
test at the D.C. Cook Plant would result in significant degradation of 
the overall containment integrity. As a result, the application of the 
regulation in these particular circumstances is not necessary to 
achieve the underlying purpose of the rule. Therefore, special 
circumstances exist pursuant to 10 CFR 50.12(a)(2)(ii).
    Accordingly, the Commission has determined that, pursuant to 10 CFR 
50.12, this exemption as described in Section III above 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.
    Based on the generic and plant-specific data, the NRC staff finds 
the basis for the licensee's proposed one-time schedular exemption to 
allow an extension of one cycle for the performance of the Appendix J, 
Type A test, provided that the general containment inspection is 
performed, to be acceptable, pursuant to 10 CFR 50.12(a) (1) and (2).
    Pursuant to 10 CFR 51.32, the Commission has determined that 
granting this exemption will not have a significant effect on the 
quality of the human environment (60 FR 32354).
    This exemption is effective upon issuance.

    Dated at Rockville, Maryland, this 6th day of July 1995.

    For the Nuclear Regulatory Commission.
Robert A. Capra,
Acting Director, Division of Reactor Projects III/IV, Office of Nuclear 
Reactor Regulation.
[FR Doc. 95-17294 Filed 7-13-95; 8:45 am]
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