ML20209E491

Safety Evaluation Supporting Amends 104 & 107 to Licenses DPR-24 & DPR-27,respectively

ML20209E491
Person / Time
Site:	Point Beach
Issue date:	08/27/1986
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20209E490	List: ML20209E487 ML20209E491 ML20209E498
References
TAC-52665, TAC-52666, NUDOCS 8609100500
Download: ML20209E491 (8)

Text

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UN6TED STATES

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g NUCLEAR REGULAYORY COMMISSION L

j WASHINGTON, D.O 20555

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SAFETY EVALUATION B" ThE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NOS.104 AND 107 TO 1

FACILITY OPERATING LICENSE NOS. DPR-24 AND DPR-27

)

WISCONSIN ELECTRIC POWER COMPANY POINT BEACH NUCLEAR PLANT, UNIT NOS. 1 AND 2 DOCKET NOS. 50-266 AND 50-301 Introduction 10 CFR Part 50, Appendix J, " Primary Reactor Containment Leakage Testing for Water-Cooled Power Reactors," specifies requirements for preoperational and periodic verification by test of the leak tight integrity of the primary reactor 4

containment, and systems and components which penetrate containment, and establishes the acceptance criteria for such tests.Section III A.3 of Appendix J specifies the methods to be used when performing an integrated (Type A) leak test of a containment. This section requires, in part, that all Type A tests shall be conducted in accordance with the provisions of American National Standard N45.4-1972 (ANSI N45.4-1972), " Leakage Rate Testing of Containment Structures for Nuclear Reactors," dated March 16, 1972.

Section 7.6 of ANSI N45.4-1972 specifies that the leakage rate test period, for any method, shall extend to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of retained internal pressure unless it can be demon-strated to the satisfaction of those responsible for the acceptance of the containment structure that the leakage rate can be accurately determined during a shorter test period, in which case the agreed upon shorter period may be used.

Sections III B and III C of Appendix J specify the test methods and acceptance criteria to be employed in determining the leak tightness of certain pressure-containing or leakage-limiting components penetrating the primary containment boundary including penetrations whose design incorporates resilient seals, gaskets, or sealant compounds and containment isolation valves.

By letters dated October 25, 1983, February 7, and April 18, 1984, Wisconsin Electric Power Company (the licensee) submitted proposed changes to the Point Beach Nuclear Plant (PBNP) Units 1 and 2 Technical Specifications (TS) for containment leakage rate testing requirements. The proposed changes modify operability and leakage rate testing requirements for the containment purge supply and exhaust valves, and incorporates specific methodologies and test acceptance criteria to be employed when performing a containment integrated leak rate test (CILRT) of less than 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> duration, as currently authorized by TS 15.4.4.I.A.2., and correct some editorial errors in the existing TS.

This Safety Evaluation addresses the licensee's proposed changes and their impact on the operation and administration of activities at PBNP.

8609100500 860827 PDR ADOCK 05000266 P

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- Summary of Evaluation The changes proposed by the licensee for operability and leak rate testing of containment purge supply and exhaust valves and the editorial changes discussed in detail below, are consistent with the requirements of 10 CFR Part 50, Appendix J or conditions of operability as described in the existing PBNP TS.

The staff agrees with these proposed changes.

With respect to the first of the two methodologies proposed by the licensee for performing CILRT's of less than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> duration, the staff finds that.insuffi-cient justification of the statistical validity of performing a short duration mass point absolute method test was provided. The staff notes that the second methodology, that contained in Bechtel Topical Report BN-TOP-1, has been previously approved generically. Thus, the licensee's proposed changes for performing reduced duration testing in accordance with BN-TOP-1 are approved and those proposed changes associated with reduced duration testing in accordance with the mass-point absolute methodology are denied.

' Evaluation Proposed Change to TS 15.3.6.C, " Containment Purge Supply and Exhaust Valves" and Associated Bases Description of Change An Item a is added to the subject specification which would allow one of the redundant valves in the purge supply and exhaust lines to be opened to perform repairs during other than cold or refueling shutdown conditions when required due to leakage in excess of that allowed pursuant to TS 15.4.4.II.B.

This condition would be allowed to exist for up to 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> at which time the reactor would have to be taken to cold shutdown.

Evaluation Existing PBNP TS 15.3.6.C requires that the containment purge supply and exhaust valves be locked closed during other than cold or refueling shutdown conditions with no allowance for opening one of the redundant valves to facilitate repair of excessive leakage identified during the semiannually required leakage test-ing. The valves are required to be locked closed because they have not been demonstrated capable of closing from the full open position during a design basis loss-of-coolant accident.

The existing TS create the potential for requiring a reactor shutdown if one of the purge supply or exhaust valves is identified as having excessive leakage during the semiannual leakage tests. The proposed TS would allow one of the redundant valves to be opened to facilitate repairs, while the remaining valve would remain locked closed. With this configuration, at least one of the two valves in series in the purge supply line and the purge exhaust line would remain closed.

Consequently, the containment boundary would be maintained at all times, and if the opened valve needed to be closed, it could be as it would have no differential pressure acting against it.

i

. Existing TS 15.4.4.II.B.1.b allows 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> to repair and retest containment penetrations employing gaskets or resilient seals that have been identified as leaking in excess of allowable limits. As the purge supply and exhaust valves have been rendered passive components of the containment boundary by the requirement to keep them locked closed during other than cold or refueling shutdown, and as they employ resilient seals, the 48 hour5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> proposed requirement for repair of these valves is consistent with existing requirements.

Based on the fact that one parge supply or exhaust valve may be opened without breaching the containment boundary and the fact that the licensee's proposal regarding a 48-hour time limit to effect repairs for identified leakage is consistent with their existing TS on repair of penetration leakage, the staff finds the proposed change acceptable.

During the review of this proposed change, it was identified that the licensee had incorrectly cross referenced TS 15.4.4.II.B.2 as the requirement to complete repairs or conduct a reactor shutdown in 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />. The correct reference is TS 15.4.4.II.B.1.b.

This was confirmed to be a typographical error during discussions with the licensee onsite on April 25, 1986. The licensee's proposed Technical Specification has been changed to correct this typographical error.

Proposed Change to TS 15.4.4.II, " Type B Tests" Description of Changes The licensee has proposed the following changes:

1.

A requirement to perform Type "B" leakage testing as defined by 10 CFR Part 50, Appendix J is added to Section A.5 of the subject TS for the containment purge supply and exhaust valves.

2.

A requirement to compare the measured leakage for the containment purge supply and exhaust valves to previously measured leakage for these valves is added to Section B of the subject TS.

3.

A requirement to perform Type "B" leakage testing as defined by 10 CFR Part 50, Appendix J at six month intervals is added to Section C of the subject TS for the containment purge supply and exhaust valves.

4.

Corresponding changes to the bases are made.

Evaluation Existing PBNP TS 15.3.6.C requires that the containment purge supply and exhaust valves be locked closed during other than cold shutdown or refueling conditions, because the valves have not been demonstrated capable of closing from the full open position during a design basis loss-of-coolant accident. These valves

, employ resilient seals. Because the valves are required to be locked closed, they have no active safety function and are passive, resilient sealed contain-ment penetrations. As such, they are subject to the Type "B" leak testing requirements of 10 CFR Part 50, Appendix J.

Item 1 above is consistent with the requirements of 10 CFR Part 50, Appendix J and is acceptable to the staff.

Item 2 above is consistent with the requirements of Section IX cf the ASME Boiler and Pressure Vessel Code for inservice testing of valves, is reflective of a need to monitor for resilient seal degradation, and represents a new requirement in the PBNP TS.

As such, this change is acceptable to the staff.

Item 3 above is also consistent with 10 FYR Part 50, Appendix J requirements.

It further requires more frequent testing than that required by Appendix J.

A portion of the licensee's change fails to address the 10 CFR Part 50, Appendix J, Section III.D.2.(a) requirement that any penetration subject to Type "B" testing be Type "B" tested if opened prior to returning the reactor to an operating mode requiring containment integrity; however, the licensee has not requested relief from this requirement and no such relief is implied or granted. Consequently, if the containment purge supply and/or exhaust valves are opened when containment integrity is not required, they must be Type "B" tested prior to returning to a condition requiring containment integrity. This change is acceptable to the staff.

The changes proposed to the bases, as identified in Item 4 above, are consistent with the proposed changes and are acceptable to the staff.

Proposed Change to TS 15.4.4.III Description of Change l

A reference to TS 15.4.4.II.A.3 is changed to TS 15.4.4.II.A.5.

l Evaluation l

The change corrects a previous typographical error and is acceptable to the

(

staff.

i Proposed Changes to TS IS.4.4.I, " Type A Periodic Integrated Leakage Rate Test" Description of Changes The licensee proposes the following changes:

1.

TS 15.4.4.I.A.2 is revised to delete the existing requirement that, "The test duration shall not be less than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> unless test experiences of at least two prior tests provide evidence of the adequacy of shorter test duration." The remaining requirement concerning verification of test accuracy remains unchanged.

s

. 1 A new TS 15.4.4.I.A.5 is added specifying two sets of criteria, one of 2.

which must be satisfied for a CILRT of less than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> duration.

The first set of criteria duplicates the criteria contained in the December 1983 Electric Power Research Institute (EPRI) Report EPRI NP-3400,

" Criteria for Determining the Duration of Integrated Leakage Rate Tests of Reactor Containments." The second set of criteria duplicates the criteria contained in Bechtel Topical Report BN-TOP-1, previously approved by the NRC.

Evaluation No NRC The change proposed to TS 15.4.4.I.A.2 is primarily administrative.

regulations or policies currently exist which would explicitly require a licensee to perform two tests demonstrating the acceptability of a CILRT The NRC has nethodology requiring a test duration of less than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

approved the test methodology of Bechtel Topical Report BN-TOP-1 without prior plant-specific demonstration of applicability. As such, this change is acceptable to the staff.

The proposed new TS 15.4.4.I.A.5 incorporates two CILRT methodologies for tests of less than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> duration. Proposed TS 15.4.4.I.A.S.a reiterates the methodology and acceptance criteria contained in the Electric Power Research Institute Report (EPRI) EPRI NP-3400 dated December 1983. This change is discussed below. Proposed TS 15.4.4.I.A.5.b reiterates the methodology and Use of acceptance criteria contained in Bechtel Topical Report BN-TOP-1.

BN-TOP-1 has been previously approved on a generic basis by the NRC; thus, the staff finds that this portion of the proposed change is acceptable.

Proposed TS 15.4.4.1.A.5.a would allow use of a short duration CILRT methodology not previously approved by the NRC. The staff reviewed the methodology as contained in the proposed TS against EPRI Report NP-3400, dated December 1983, 10 CFR Part 50, Appendix J requirements, and a previous PBNP CILRT performed on Unit 1 in 1984 with the following results.

Proposed TS 15.4.4.I.A.5.a.6 establishes an acceptance criteria as 1.

follows: The calculated LSF (Least Squares Fit) leakage rate as a function of time shall have stabilized with a negligible positive or negative slope, as demonstrated by the following:

(L - 'n-1) x 100 n

5 10 n-1) C'c - 'n)

(t

-t n

4

= - - - - -, - - - - -~

--e

,--,,,----m---,w a-

~

.-n--

w--

-mn---,-

- -, - -n

.g.---

+

• Where L, = Final Test Point LSF leakage rate.

l L,_g = Leakage rate for data points taken within the previous hour.

t = Time in hours of the last data point.

t _g = Time in hours for the data point used for L _g, L = Test leakage criteria (75% of allowable leakage at test pressure).

When compared to the corresponding EPRI NP-3400 criteria, the following discrepancy was noted:

EPRI NP-3400 proposes the above criteria as an adjunct to the criteria contained in ANSI /ANS 56.8-1981, " Containment System Leakage Testing Requirements." The licensee's criteria do not include those from ANSI /ANS 56.8-1981, most notably criteria on minimum test duration and number of data points. Further, no justification as to the validity of this criteria with regard to the statistical acceptability of test data is provided.

2.

Neither the licensee's proposed methodology nor that contained in EPRI NP-3400 specify containment test condition stabilization prior to the start of the test as required by 10 CFR Part 50, Appendix J, Section III.A.I.(c).

Failure to stabilize conditions prior to the start of the test could produce false results of a satisfactory test.

It is worthy of note, that the licensee did include stabilization criteria in that portion of their proposed TS change incorporating the Bechtel Topical Report BN-TCP-1 methodology.

3.

Neither the licensee's proposal nor the methodology contained in EPRI NP-3400 specify a minimum data acquisition frequency. ANSI'N45.4-1972 requires data to be taken at least hourly; however, this would appear to be inadequate for the purposes of the licensee's methodology. Proposed TS 15.4.4.I.A.5.a.(7) establishes an acceptance criteria for a successful CILRT that the difference between the 95 percent confidence level ISF leakage and the calculated LSF leakage must be constant or decreasing for all points taken during the last test hour.

If data is taken only at hourly intervals, this is a two point comparison only which may be insensitive to excessive data scatter. This is particularly true as the test duration increases and the sensitivity of both the measured and 95 percent confidence level LSF les' sages to data scatter decreases.

4.

As noted in Section 5 of EPRI NP-3400, more validation of the criteria contained therein is necessary as the original effort was based on only 53

+

. 4 tests. This was discussed with the licensee and a representative of the Quadex Corporation which prepared EPRI NP-3400. During this discussion, it was determined that significantly more validation had taken place using data from successful CILRT's; however, only limited work had been done using data from failed CILRT's and none of those were marginal failures where a more significant potential for falsely predicting a successful result exists.

It would thus appear, that additional validation is warranted.

5.

Between the period March 30 through April 1, 1984, the licensee conducted a Unit 1 CILRT. During this CILRT, witnessed by NRC Region I}I inspection personnel, the licensee attempted to validate their proposed criteria.

Application of the criteria would have allowed test termination after 10 1/2 hours; however, subsequent data indicated that the TS allowable leakage was exceeded between the 14th through 28th hour of the test. While the test was ultimately successful after approximately 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />, the final leakage rate nearured was greater than that predicted after 10 1/2 hours.

Thus, the result obtained using the proposed criteria was potentially nonconservative.

Based'on the discrepancies in and uncertainties associated with the licensee's proposed short duration CILRT methodology, their proposal for using the mass point methodology is denied.

Environmental Consideration These amendments involve a change in the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20.

The staff has determined that the amendment relating to operability and testing of the containment purge supply and exhaust valves involves no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure. The Commission has previously published a proposed finding that this amendment involves no significant hazards consideration and there has been no public comment on such finding. Accordingly, i

this amenoment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9). These amendments also involve changes in i

recordkeeping, reporting or administrative procedures or requiremeats.

Accordingly, with respect to these items, the amendments meet the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(10). Pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the issuance of this amendment.

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~...,,, _ _, _, _ _. _ _, _. _ _

Conclusion We have concluded, bas'ed on the considerations discussed above relative to operability and testing requirements for the containment purge supply and exhaust valves, that (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, and (2) such activities will be conducted in compliance with the Commission's regulations, and 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:

T. Colburn W. Guldemond Date: August 27, 1986 A