ML20128L857

Safety Evaluation Supporting Amend 219 to License DPR-49

ML20128L857
Person / Time
Site:	Duane Arnold
Issue date:	10/04/1996
From:	NRC (Affiliation Not Assigned)
To:
Shared Package
ML20128L850	List: ML20128L844 ML20128L857
References
NUDOCS 9610150214
Download: ML20128L857 (4)

Text

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NUCLEAR REGULATORY COMMISSION ff WASHINGTON, D.C. 2C666 0001

%7 W R* f SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 219 TO FACILITY OPERATING LICENSE NO. DPR-49 IES UTILITIES INC.

CENTRAL IOWA POWER COOPERATIVE CORN BELT POWER COOPERATIVE DUANE ARNOLD ENERGY CENTER DOCKET NO. 50-331 f

1.0 INTRODUCTION

On September 12, 1995, the U.S. Nuclear Regulatory Commission (NRC) approved issuance of a revision to 10 CFR Part 50, Appendix J, " Primary Reactor Containment Leakage Testing for Water-Cooled Power Reactors" which was subsequently published in the Federal Reaister on September 26, 1995, and became effective on October 26, 1995. The NRC added Option B, " Performance-Based Requirements," to allow licensees to voluntarily replace the prescriptive testing requirements of 10 CFR Part 50, Appendix J, with testing i

requirements based on both overall performance and the performance of individual components.

By letters dated December 22, 1995, and September 20, 1996, IES Utilities Inc.

(the licensee) requested changes to the Technical Specifications (TS) for the Duane Arnold Energy Center. The proposed changes would permit implementation of 10 CFR Part 50, Appendix J, Option B.

The licensee has established a

" Primary Containment Leakage Rate Testing Program" and proposed adding this program to the TS. The program references Regulatory Guide 1.163,

" Performance-Based Containment Leak Test Program," dated September 1995, which l

specifies a method acceptable to the NRC for complying with Option B.

2.0 BACKGROUND

Compliance with 10 CFR Part 50, Appendix J, provides assurance that the primary containment, including those systems and components which penetrate the primary containment, do not exceed the allowable leakage rate specified in the TS and Bases. The allowable leakage rate is determined so that the leakage rate assumed in the safety analyses is not exceeded.

On February 4,1992, the NRC published a notice in the Federal Reaister (57 FR 4166) discussing a planned initiative to begin eliminating requirements marginal to safety that impose a significant regulatory burden.

Part 50, Appendix J, " Primary Containment Leakage Testing for Water-Cooled Power Reactors," was considered for this initiative and the staff undertook a study of possible changes to this regulation. The study examined the previous performance history of domestic containments and examined the effect on risk of a revision to the requirements of Appendix J.

The results of this study i

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i are reported in NUREG-1493, " Performance-Based Leak-Test Program".

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Based on the results of this study, the staff developed a performance-based

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approach to containment leakage rate testing. On September 12, 1995, the NRC approved issuance of this revision to 10 CFR Part 50, Appendix J, which was subsequently published in the Federal Reaister on September 26, 1995, and i

became effective on October 26, 1995. The revision added Option B,

" Performance-Based Requirements," to Appendix J to allow licensees to i

voluntarily replace the prescriptive testing requirements of Appendix J with testing requirements based on both overall and individual component leakage 4

l rate performance.

I Regulatory Guide 1.163, "Perfomance-Based Containment Leak Test Program,"

dated September 1995, was developed as a method acceptable to the NRC staff i

for implementing Option B.

This regulatory guide states that the Nuclear Energy Institute (NEI) guidance document NEI 94-01, Rev. O, " Industry l

Guideline for Implementing Performance-Based Option of 10 CFR Part 50, Appendix J," provides methods acceptable to the NRC staff for complying with i

i Option B with four exceptions which are described therein.

i Option B requires that the Regulatory Guide or other implementation document i

used by a licensee to develop a performance-based leakage testing program must be included, by general reference, in the plant TS. The licensee has j

referenced Regulatory Guide 1.163, dated September 1995, in the proposed DAEC j

TS.

Regulatory Guide 1.163, dated September 1995, specifies an extension in Type A test frequency to at least one test in 10 years based upon two consecutive successful tests.

Type B tests may be extended up to a maximum interval of 10 j

years based upon completion of two consecutive successful tests and Type C j

tests may be extended up to 5 years based on two consecutive successful tests.

i By letter dated October 20, 1995, NEI proposed TS to implement Option B.

1 After some discussion, the staff and NEI agreed on final TS which were i

transmitted to NEI in a letter dated November 2,1995. These TS are to serve i

as a model for licensees to develop plant specific TS in preparing amendment i

requests to implement Option B.

l In order for a licensee to determine the performance of each component, a

factors that are indicative of rer affect performance, such as an administrative leakage limit, rest be established. The administrative limit is selected to be indicative of the potential onset of component degradation.

I Although these limits are subject to NRC inspection to assure that they are f

selected in a reasonable manner, they are not TS requirements.

Failure to 1

meet an administrative limit requires the licensee to return to the~ minimum i

value of the test interval.

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Option B requires that the licensee maintain records to show that the criteria for Type A, B and C tests have been met.

In addition, the licensee must 4

maintain comparisons of the performance of the overall containment system and i

the individual components to show that the test intervals are adequate. These i

records are subject to NRC inspection.

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- 3.0 EVALUATION The licensee's December 22, 1995, ani! September 20, 1996, letters to the NRC propose to establish a " Primary Containment Leakage Rate Testing Program" and propose to add this program to the TS. The program references Regulatory i

Guide 1.163, " Performance-Based Containment Leak Test Program," dated September 1995, which specifies methods acceptable to the NRC for complying with Option B.

This requires a change to existing TS 3.7.A, 4.7.A, 6.11.3, Table 6.11-1, and the addition of the " Primary Containment Leakage Rate Testing Program" to Section 6.12.

Corresponding bases were also modified.

Option B permits a licensee to choose Type A; or Type B and C; or Type A, B and C; testing to be done on a performance basis. The licensee has elected to l

perform Type A, B, and C testing on a performance basis.

The TS changes proposed by the licensee are in compliance with the requirements of Option 8 and consistent with the guidance of Regulatory Guide 1.163, dated September 1995.

Further, despite the different format of the licensee's current TS, all of the important elements of the model TS guidance provided in the NRC letter to NEI dated November 2,1995, are included in the proposed TS. The licensee has proposed a change that either deviates from i

those in the model TS.

It is discussed below.

Air Lock Door Seal Leak Rate Testina (Deviation)

The proposed TS 6.12, " Primary Containment Leakage Rate Testing Program,"

deviates from the model TS in that the air lock leakage rate testing acceptance criteria do not include a criterion for the separate testing of a door (door seals). This is because the air lock doors at DAEC are equipped with a single seal each, rather than dual seals, so the doors are not separately testable. The only way to test is to test the entire air lock; therefore, the proposed TS only includes an acceptance criterion for testing in that manner. The staff finds this acceptable.

3.1 Additional TS Chanaes The licensee proposed several additional changes that are separate from the Appendix J, Option B TS modification request. Current TS 4.7.A.I.e., " Seal Replacement and Mechanical Limiter," requires the T-ring inflatable seals on seven containment purge isolation valves to be replaced at 4-year intervals; it also requires periodic verification that the mechanical modification which limits the maximum opening angle for the same seven valves is intact. The proposal would delete this TS.

3.1.1 Seal Replacement The licensee's original submittal, dated December 22, 1995, requested deletion of the set interval for purge valve seal replacement. By letter dated September 20, 1996, the licensee provided additional details. The requirement was added to the TS in 1984 in response to generic staff concerns regarding purging and venting operations; also added was a requirement to leak test the valves every 3 months. The staff was concerned that potential rapid degradation of the resilient seals on containment purge / vent valves, due to

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' wear, aging, and environmental exposure, could lead to undetected gross failure of the valves' leak-tight integrity.

In addition to either ceasing purging / venting during plant operation or limiting it to a strict minimum, the staff requested more frequent testing (compared to the Appendix J interval

[ refueling]) and/or seal replacement on a set interval, but not necessarily both. The licensee conservatively chose to do both.

The licensee's testing experience since 1984 has been very good, with few problems, and none in the last 7 years. Further, licensee engineering evaluations have found a longer replacement interval (7.5 years) to be appropriate.

Seal replacement at a set interval is essentially an alternative to increased leak test frequency.

lhe DAEC TS will retain the 3-month testing interval and the seal replacement requirements will be retained in the UFSAR and plant procedures.

In 10 CFR 50.59(a)(1), it specifically states that changes made by a licensee to the UFSAR and plant procedures are subject to the requirements of 10 CFR 50.59.

Based on the above discussion, the staff finds that quarterly purge valve leak testing is sufficient for timely detection of seal degradation, and that the deletion from the TS of the set interval for seal replacement is therefore acceptable.

3.1.2 Mechanical limiter Periodic surveillance of the mechanical modification that limits the opening angle of the purge valves is only necessary if the limiter is not permanently installed, consistent with the Improved Standard TS. However, the subject purge valves are permanently blocked to restrict opening to 30 degrees.

Therefore, the staff finds acceptable the deletion of this requirement from the TS.

3.2 Administrative Chanaes This amendment also includes several minor administrative changes in the TS l

Table of Contents which the staff has reviewed and finds acceptable.

4.0 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 had no comments.

5.0 ENVIRONMENTAL CONSIDERATION

The amendment changes a requirement with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 or changes a surveillance requirement.

The NRC staff has determined that the amendment involves no significant increase in the amounts, and no

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-s-significant change in the types, of any effluent that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure.

The Commission has previously issued a proposed finding that the amendment involves no significant hazards consideration and there has been no public comment on such finding (61 FR 3499). 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.

6.0 CONCLUSION

The Commission has concluded, based on the considerations discussed above, that:

(1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.

Principal Contributors:

G. Kelly J. Pulsipher Date: October 4, 1996

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