[Federal Register Volume 60, Number 119 (Wednesday, June 21, 1995)]
[Notices]
[Pages 32381-32382]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-15143]
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NUCLEAR REGULATORY COMMISSION
[Docket No. 50-255]
Consumers Power Company (Palisades Plant); Exemption
I
Consumers Power Company (CPCo, the licensee) is the holder of
Facility Operating License No. DPR-20 which authorizes operation of the
Palisades Plant, a pressurized water reactor (PWR) located in Van Buren
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 of the primary containment.
III
By letter dated March 17, 1995, as supplemented April 26, 1995,
CPCo 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 21 months (from the 1995 refueling outage, currently
scheduled to begin in May 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, paragraphs (a)(2) (ii) and (iii), as the basis for the
exemption, and states that the exemption would eliminate a cost of $1
million 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. CPCo 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 Palisades Plant that, with the
exception of the 1978 test results, 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 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. The licensee also references the proposed revision to Appendix J
which would reduce the frequency of Type A tests.
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 21 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) and (iii), 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 and would impose excessive cost.
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 or becoming unknown. 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
following the submittal of its Corrective Action Plan on June 30, 1986.
The Corrective Action Plan was submitting following three consecutive
Type A test failures, of which one was the 1978 test failure. However,
the licensee has noted that the containment penetration local leak rate
tests (LLRT, Type B and C tests) accounted for the majority of the
before maintenance adjustment to the as-found ILRT (Type A) results
during the as-found test failures. The penetration associated with the
1978 test failure was significantly modified in the mid-1980's to
improve the LLRT test configuration to properly monitor the entire
penetration boundary. In addition, the licensee aggressively replaced
or repaired the valves and penetrations that accounted for the as-found
test failures, with no repeat occurrences.
The NRC staff reviewed the LLRT Corrective Action Plan and granted
an [[Page 32382]] exemption to Appendix J for Palisades on September
17, 1987. The exemption stated that if the conditions of the Plan were
met, and the next scheduled Type A test was successfully completed,
then normal resumption of the Type A test frequency would be allowed.
The two following Type A tests (11/88 and 2/91) passed with significant
margin and the licensee has noted that the LLRT Correction Action Plan
was successful in eliminating original plant design, maintenance, and
testing deficiencies. In addition, 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 Palisades containment structure consists of a post-tensioned,
reinforced concrete cylinder and dome connected to and supported by a
reinforced concrete foundation slab. The containment structure is
designed to ensure that leakage will not exceed 0.1% per day by weight
at the peak pressure of the design basis accident. A concrete shield
building surrounds the containment vessel, providing a shield building
annulus between the two structures. Penetrations of the containment
vessel for piping, electrical conductors, ducts, and access hatches are
provided with double barriers against leakage.
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 LLRTs (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 Palisades
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 Palisades 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, and compliance would impose
excess cost and undue hardship. Therefore, special circumstances exist
pursuant to 10 CFR 50.12(a)(2) (ii) and (iii).
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 30115).
This exemption is effective upon issuance.
Dated at Rockville, Maryland, this 14th day of June 1995.
For the Nuclear Regulatory Commission.
John N. Hannon,
Acting Deputy Director, Division of Reactor Projects III/IV, Office of
Nuclear Reactor Regulation.
[FR Doc. 95-15143 Filed 6-20-95; 8:45 am]
BILLING CODE 7590-01-M
