ML20055D234
| ML20055D234 | |
| Person / Time | |
|---|---|
| Site: | Duane Arnold  |
| Issue date: | 06/29/1990 |
| From: | Crutchfield D Office of Nuclear Reactor Regulation |
| To: | IES UTILITIES INC., (FORMERLY IOWA ELECTRIC LIGHT |
| Shared Package | |
| ML20055D235 | List: |
| References | |
| NUDOCS 9007050214 | |
| Download: ML20055D234 (6) | |
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's UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION In the Matter of.
IOWA ELECTRIC LIGHT AND Docket No. 50-331 POWER COMPANY, CENTRAL IOWA POWER COOPERATIVE, AND CORN BELT POWER COOPERATIVE (Duane Arnold Energy Center)
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EXEMPTION r
I.
Iowa Electric Light'and Power Company, et al. (the licensee) is the holder of Facility Operating License No. DPR-49 which authorizes the operation of the Duane Arnold Energy Center (DAEC) at steady state reactor power levels not in excess of 1658 megawatts thermal. The license provides, among other things, that it is subject to all rules,. regulations and Orders of the Commission now and hereafter in effect. The facility consists of a boiling water reactor located at the licensee's site near Palo in Linn County, 1
Iowa.
II.
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.The Code of Federal Regulations,10 CFR 50.54(o), specifies that primary-reactor containments for water-cooled power reactors.shall comply with Appendix J, " Primary Reactor Containment Leakage Testing for Water-Cooled Power Reactors."Section III.A.6.(b) of Appendix J to 10 CFR Part 50 states the following:
If two consecutive periodic Type A tests fail to teet the applicable acceptance criteria in III.A.S.(b), notwithstanding the periodic retest schedule of III.D., a Type A test shall be performed at each plant l
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i shutdown for refueling or approximately every 18 months, whichever occurs first, until two consecutive Type A tests meet the acceptance criteria in III.A.S.(b), after which time the retest schedule specified 4
in III.D. may be resumed.
The' containment integrated leak rate tests (Type A tests) performed 'during the 1985 and 1987 refueling outages at the DAEC were considered to be failures in the "as-found" condition due to penalties incurred as a result of leakage measured in Type B and Type C local leak rate tests (LLRTs). The Type A test
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conducted during the 1988 refueling outage was successful in the "as-found" condition.
However, the licensee is still required to conduct a Type A test at the upcoming refueling outage, commencing in June 1990.
As an alternative to performing the required Type A test, the licensee has submitted a Corrective Action Plan to eliminate excessive local leakage in accordance with the guidance provided in NRC Information Notice 85-71,
" Containment Integrated Leak Rate Tests," dated August 22, 1985. The Corrective Action Plan is in lieu of the increased test frequency required by Section III. A.6.(b) of Appendix J to 10 CFR Part 50. Therefore, an exemption from this requirement is needed.
III.
By letter dated April 2, 1990, the licensee requested a one-time exemption from 10 CFR Part 50, Appendix J, Section III.A.6.(b), to allow a return to the normal Type A retest schedule of Section III.D. of Appendix J.
The accelerated Type ~A test frequency was required due to failures of the Type A tests (in the "as-found" condition) conducted at the DAEC in 1985 and 1987. These test failures were the direct result of leakage rate penalties from Type B and C local leak rate tests (LLRTs), which are added to the measured Type A leakage
3 rate to calculate the total "as-found" containment integrated leakage rate.
Specifically, excessive leakage from the inboard feedwater check valves l
and from the Main Steam Isolation Valves (MSIVs), as measured during Type.C testing.of those valves, resulted in the total Type A leakage exceeding the acceptance criteria. Although a successful Type A test was performed in December 1988, leakage from the inboard feedwater check valves and MSIVs again comprised the major portion (63%) of the total "as-found" leakage.
The licensee's Corrective Action Plan describes the modification, testing and preventative maintenance programs implemented or planned to improve the leakage characteristics for these valve. The inboard feedwater check valves were modified during the 1988 refueling outage, including the installation of-soft seats, which have been effective in reducing leakage from similar valves at other facilities. The effectiveness of these modifications-will be confirmed through the Type C tests of these valves performed at each refueling outage.
In addition, the preventative maintenance (PM) program will require disassembly and inspection of these valves at each refueling-outage, thereby ensuring that degradation will be detected and corrective maintenance performed.
L Extensive modifications to all eight MSIVs will be made during the 1990 l
I refueling outage, as described in the Corrective Action Plan. These modifications l
address the primary contributors to local leak rate test failures as identified l
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by the industry and the NRC. Additional modifications to the MSIVs are also
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directed at improving valve reliability. These modifications are expected to significantly improve MSIV leakage performance, as they have been proven effective through industry experience or testing. Local leak rate tests will be performed l
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. e on the MSIVs at each refueling outage, in addition to the ic-+4ng required by t
the DAEC Inservice Testing Program, normally performed in conjunction with Type C tests.
This testing will confirm the effectiveness of the modifications.
t The PM program for the MSIVs will also require disassembly and inspection of each valve at least once per three operating cycles, although excessive leakage identified during testing ~would necessitate immediate disassembly and repair.
The PM program for both the feedwater check valves and the MSIVs will also provide trending information for.the continuing evaluation of valve performance, which will dictate changes to PM practices or further design improvements.
The licensee's Corrective Action Plan for the inboard feedwater check valves and MSIVs, consisting of modification, testing and preventative maintenance programs, will provide an equivalent degree of assurance that containment integrity will be maintained as that provided by an additional Type A test performed on the accelerated frequency specified by Section III.A.6.(b) of Appendix J.
The NRC staff concludes that a return to the normal retest schedule of Section III.D. of Appendix J is justified. The staff's Safety Evaluation dated June 29, 1990 provides additional details and bases supporting the requested exemption.
IV.
The underlying purpose of the requirements of Section III.A.6.(b) of Appendix J to 10 CFR Part 50 is to ensure the integrity of the primary contain-ment and its penetrations.
As discussed above, the underlying purpose is achieved through the licensee's comprehensive Corrective Action Plan. Thus, an equivalent level of protection is provided.
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5 Accordingly, the Comission 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 comon defense and security. The Comission has further determined that special circumstances,as.setforthin10CFR50.12(a)(2)(ii)arepresent, justifying the exemption; namely that application of the regulation in this particular circumstance is not necessary to achieve the underlying purpose of the rule.
Accordingly, the Comission hereby grants an exemption to Section III.A.6.(b).
of Appendix J to 10 CFR Part 50 to allow the licensee to resume the Type A i
retest schedule of Section III.D. of Appendix J for the Duane Arnold Energy Center.
If the next Type A test is deemed a failure by the NRC acceptance criteria, the. schedule for future Type A tests must be reviewed and approved by the Comission, as required by Section III. A.6.(a) of Appendix J.
Pursuant to 10 CFR 51.21, 51.32, and 51.35, an environmental assessment and
.i finding of no significant impact has been prepared and published in the Federal Register on June 27,1990 (55 FR 26305).
Accordingly, based upon the environmental assessment, the Comission has determined that the granting of this exemption will not have a significant effact on the quality of the human environment.
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I A copy of the licensee's request for exemption dated April 2, 1990, is available for public inspection at the Comission's Public Document Room, 2120 L Street, N.W., Washington, D.C., and at the Cedar Rapids Public Library, 500 First Street SE, Cedar Rapids, Iowa, 52401.
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This exemption is effective upon issuance.
FOR THE NUCLEAR REGULATORY COMMISSION-art 2
Cen is 4. CrutcInfie
,D ecto Division of Reactor Pr ects III, IV, V and Special Projects Office of Nuclear Reactor Regulation Dated at Rockville, Maryland this29th day of June 1990 i
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