ML20079D650

Safety Evaluation Supporting Amend 171 to License DPR-49

ML20079D650
Person / Time
Site:	Duane Arnold
Issue date:	07/12/1991
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20079D649	List: ML20079D648 ML20079D650
References
NUDOCS 9107230330
Download: ML20079D650 (3)

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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 171 TO FACILITY OPERATING LICENSE NO. DPR-49 10WA ELECTRIC LIGHT AND POWER COMPANY l

CENTRAL IOWA POWER COOPERATIVE CORN BELT POWER COOPERATIVE DUANE ARNOLD ENERGY CENTER DOCKET NO. 50-331' 1 ~. 0 INTRODUCTION By letter dated December-14, 1990, Iowa Electric Light and Power Company,-(IELP) the licensee, submitted c request for amendinent to Facility Operating License No. DPR-49, to delete a-cequirement to exercise the Main Steam Line Isolation Valves (MSIVs) weekly by partial closure and reopening.

Additionally, the first' footnote on Table 3.7-3,' " Primary Containment Power Operated Isolation Valves,"

~would be revised to clarify the applicable testing for the MSIVs.

On May 23, 1991, IELP submitted a request for a Temporary Waiver of Compliance from the requirements for the-weekly partial stroke testing of the MSIVs, pending staff approval of a permanent change to the Technical Specifications (TSs). The request was based in-part on the licensee's-concern that observed problems with. stem galling-of one MSIV could be exacerbated by the weekly partial stroke test. On May 24, 1991, the staff

-granted the. requested waiver from TS Surveillance Requirement.4.7.0.1.C, effective until a permanent change to the TS.is issued..

2.0 EVALUATION Duane Arnold Technical Specification 4.7.D.'1.c requires that the main steam

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line power-operated isolation valves be exercised at least once per week by

-partial closure and recpening. The licensee determined that the weekly.

exercise of the MSIVs was originally intended to. demonstrate that the MSIV' pilot valve is not binding by exercising a_ test pilot valve of,the same design.. Those solenoid oparated pilot valves which were susceptible to binding were replaced, but che Technical Specifications (TS) had not been

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revised to remove the weekly exercise of the MSIVs.

Each quarter, reactor power is reduced to less than 75% and_a fast full-stroke test of each MSIV is performed utilizing the main pilot' valve per TS 4.7.D.1 b.(2) and ASME Code Section XI requirements for inservice testing.

This quarterly surveillance tests the safety function of the valves to close and ensures t

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. that the stroke times are within the limits of operability for the valves.

Any binding of the solenoid operated pilot valves or of the MSIVs should be i

identified during the quarterly surveillance.

NUREG-0737, item 11.K 3.16 provided recommendations to reduce the frequency of cha'ilengestosafetyreliefvalves. One of the recommendations was to eliminate the weekly partial-stroke exercise of the MSIVs. Partial-stroke exercising can result in a transient if a test circuit malfunction causes the tested MSIV to fully close.

Because the partial-stroke exercise tests are generally performed 4

during full power operation, the resulting transient could involve reactor trips.

This TS change is therefore consistent with the NilREG-0737 recommendation.

The first footnote of Table 3.7-3 specifies that primary containment power l

operated isolation valves in the main sfeam, containment compressor suction, containment compressor discharge, reactor building closed cooling water supply / return, and the well water supply /retern systems were subject to the i

l requirements of 4.7.D.1.a only, which requires primary containment isolation I

valves be tested once per operating cycle for simulated automatic initiation l

and closure times. This footnote was necessary to stipulate that, due to plant operational limitations, the specific valves would not be subject to quarterly closing and reopening as required by 4.7.D.1.b.(1) for all normally l

open power operated isolation valves.

The clarification in the proposed Technical Specification change would stipulate that the MSIVs are subject to l

4.7 D.1.b(2), which requires quarterly valve stroking and verification of l

closure time.

Tha quarterly testing is more stringent than 4.7.D.1.a.

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l specific requirement is provided for the MSIVs because power reduction to l

1ee,s than 75% is necessary to perform the te:; ting.

Because the proposed TS cnange is consistent with the inservice testing

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I requirements of ASME Code Section XI, the proposed amendment deleting the weekly MSIV partial-stroke test and clarifying the Table 3.7-3 footnote is l

acceptable to'the staff.

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3.0 STATE CONSULTATION

In accordance with the Commission's regulations, the Iowa State official was notified of the proposed issuance of the amendment.

The State official l.

had no comments, l

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4.0 ENVIRONMENTAL CONSIDERATION

S This amendment changes a requirement with respect to instaliation-or use of a facility component located within the restricted area as defined in 10 CFR l

Part 20 or changes a surveillance requirement. The staff has determined that l

the amendment involves no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that l

l there is no significant increase in individual or cumulative occupational l

radiation exposure. The Commission has previously issued a proposed finding i

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3 that the amendment involves no significant hazards consideration and there has been no public comment on such finding. Accordingly, the amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9).

Pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendment.

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5.0 CONCLUSION

The staff has concluded, based on the considerations discussed above, that: (1) be endangered by operation in the proposed manner, (2) y of the public will not there is reasonable assurance that the health and safet such activities will be conducted in compliance with tne Cnmmission's regulations, and (3) the issuance of the amendment will not be inimical to the commve defense and security or to the health and safety of the public.

Principal Contributor:

P. Campbell, NRR Date: July 12, 1991

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