ML20127E208

Requests Exemption from 10CFR50,App J Type a Test Frequency. Exemption Required to Allow Next Scheduled Type a Test to Be Decoupled from Inservice Insps & 10-yr Inservice Insp Period.Justification for Exemption Encl

ML20127E208
Person / Time
Site:	Zion File:ZionSolutions icon.png
Issue date:	01/12/1993
From:	Stimac S COMMONWEALTH EDISON CO.
To:	Murley T NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM), Office of Nuclear Reactor Regulation
References
NUDOCS 9301190203
Download: ML20127E208 (8)

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• 's Downers Grove, filinois 60515 January 12, 1993 Dr. Thomas E. Hurley, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission At t ri . Document Control Desk

Subject:

Zion Nuclear Generating Station Unit 1 Request for Exemption from 10 CFR 50, Appendix J Type A Test frequency MRC DochetJio,_50-295

Dear Dr. Murley:

Pursuant to 10 CFR 50.12(a), Commonwealth Edison Company (CECO) requests an exemption for Zion Unit I from the requirements of Title 10 of the Code of federal Regulations. Part 50 (10 CFR 50), Appendix J, " Primary Reactor Containment Leakage Testing for Hater-Cooled Power Reactors." 10 CFR 50, Appendix J, Section Ill.D.1.(a) specifies that a set of three containment overall integrated leakage rate tests (ILRTs), or Type A tests, be performed at approximately equal intervals during each 10-year service period. In addition, it specifies that the third test of each set shall be conducted when the plant is shutdown for the 10-year plant inservice inspections. This exemption is requested in order to uncouple the Type A testing frequency from the 10-year service period and the third Type A test from the 10-year inservice inspections.

Zion Unit I completed its second Type A test of the second ten year service period on March 3, 1992. The next scheduled refueling outage for Unit 1 is the cycle 13 refueling outage which is also the 10-year inservice inspection outage. The cycle 13 refueling outage is scheduled to begin October 21, 1993. Since this interval between the successive Type A tests is

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only 19 months, tne station proposes to move the next scheduled Type A test to the cycle 14 refueling outage currently scheduled to start in September 1995.

The interval between the two successive Tyra A tests on the unit would then be 43 months. An exemption is required to allow the next scheduled Type A test to be decoupled from the inservice inspections and the 10-year inservice inspection period.

An exemption from the Type A testing schedular requirements is appropriate in that performing two Type A tests in 19 months and the Type A test and the ISI at the same time is not necessary to achieve the underlying purpose of the rule. Attachment A to this letter contains detailed justification for the exemption in accordance with the guidelines established in 10 CFR 50.12(a).

Attachment B provides additional information regarding the history of past ILRT tests of Zion Station Unit 1. The concept and general bases for this exemption request were discussed at a meeting between NRC (C. Shiraki, et al) and CECO (T. Schuster, et al) held on December 8, 1992 at NRR offices and clartfled in a subsequent teleconference.

9301190203 930112 PDR ADOCK 05000295 P PDR ZNLD/2434/7

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'Dr'. Thomas E. Murley January 12, 1993 As noted above, the cycle 13 refueling outage is scheduled to begin October 21, 1993. To ensure sufficient time for outage planning activities, Commonwealth Edison Company requests that the proposed exemption request be approved no later than June 1, 1993.

This request has been reviewed and approved by the Zion Station On-Site Review Committee in accordance with Company procedure.

To the best of my knowledge and belief, the statements contained herein are true and correct. In some respects these statements are not based on my personal knowledge but upon information received from other CECO P.nd contractor employees. Such information has been reviewed in accordance with company practice and I believe it to be reliable.

Please direct any questions you may have regarding this matter to this office.

Very Truly Yours,

. L Stephen F. Stimac Nuclear Licensing Administrator Attachments:

A) Justification for Exemption B) Unit 1 Type A Test History Cc:

A. Bert Davis, Regional Administrator - RIII C.Y. Shiraki, Project Manager - NRR-J.D. Smith, Senior Resident Inspector - Zion Office of Nuclear Facility Safety _IDNS l 'L4A1 adk.~ .

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ATTACHMENT A JUSTiflCATION FOR EXEMPTION FROM 10 CFR 50, APPENDIX J. TYPE A TEST FREQUENCY EXEMPTION:

Comnonwealth Edison Company (Ceco) requests an exemption for Zion Unit I f rom the Type A testing schedule of 10 CFR 50, Appendix J, Section 111.D.I.(a). This section of Appendix J requires a set of three containment overall integrated leakage rate tests (Type A tests) be performed at approximately equal intervals during each 10-year service period with the third test of each set being -

conducted when the plant is shutdown for the 10-year inservice inspections.

DISCUSSION:

General Design Criteria (GDC) 52 of Appendix A to 10 CFR 50 requires that each reactor containment be designed so that periodic integrated leakage rate testing can be conducted to assure containment isolation integrity. Type A tests are required by 10 CFR 50 Appendix J to assure that the containment leakage following a design basis accident is less than the maximum allowable leak rate assumed in the accident analysis. Appendix J also requires local leakage rate tests (Type B and C tests) be conducted of leakage through containment penetrations and isolation valves to assure containment integrity during an accident.

ASME Boiler and Pressure Vessel Code for mechanical systeras and components establishes the 10-year inservice inspection (ISI) ~

period. The purpose of the inspection program is to ensure that structural integrity of Class 1, 2, and 3 components are maintained in accordance with the requirements of ASME Code Section XI.

Compliance with 10 CFR 50, Appendix J, Section III.D.l.(a), to perform a Type A test and the 10-year ISI during the same outage does not appear to serve the underlying purpose of the rule. Conducting the third Type A test during the same outage as the shutdown for the 10-year plant ISI does not enhance the purpose, or provide further assurance of containment integrity above that which has already been demonstrated. Therefore, an exemption is requested to uncouple the third Type A test from the ten-year inservice inspections. This requested uncoupling of the two programs has no safety consequences because the methodology and acceptance criteria in Appendix J and the structural integrity requirements of Class 1, 2, and 3 components in the ASME Code are not being changed by this proposed exemption.

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The second Type A test of the second ten year ISI service period was conducted during the cycle 12 refueling outage in March of 1992. The as-left leakage rate was .01620 weight percent per day calculated with a 95 percent upper confidence level. This is well below the acceptance criteria of .075 weight percent per day. The unit shutdown for the 10-year unit ISI is the cycle 13 refueling outage scheduled for September 1993. In order to meet the Appendix J.

Section III.D.1.(a), test schedule requirements, the third Type A test would also have to be scheduled during the cycle 13 refueling outage.

Due to NRC concerns with the validity of the test results from the second and third Type A tests of the first ten year service period, a fourth test was performed on 7/27/84 approximately eight months into l the second ten year service period. The first test of the second service period was done in March of 1988, 43 months after the last test and 51 months into the service period. The second test was not done until 48 months later due to the length of fuel cycle 11 which was 29 months long due to two major forced outages in which the unit was down for a total of 265 days. To meet the three tests in a ten year service period, the third test would have to be done during the cycle 13 refueling outage only 19 months after the second Type A test.

) In order to prevent having to perforiit_ successive Type A tests in such a short interval, we are proposing that the next Type A test be performed in the cycle 14 refueling outage scheduled for September 1995. Then the interval between the successive tests would be 42 months. This interval between successive tests is closer to the approximate 40 month separation which is the intent of the current rule and is consistent with the general interval Zion Unit I has maintained to this point (see Attachment B). In addition, this interval is consistent with that of the proposed revision to 10 CFR 50 Appendix J (51FR39538, October 29, 1986).

He therefore request an exemption from the requirement to conduct three Type A tests in a ten year _ service period. In lieu of the current Appendix J scheduling requirement we propose to perform in any ten year period from the date of a Type A test, counting that test, at least three Type A tests at approximately equal intervals with no more than 50 months separation between the successive _ tests.

The purpose of the Type A test, to provide periodic ver_1fication by tests of the leak-tight integrity of the primary reactor containment, systems and. components which penetrate containment, will not be l adversely impacted by this change in time basis. _The Type A tests are being and will, continue to be performed on a regular periodicity. In addition, since the most suspect leakage paths are through valves and penetrations, and the Type B and C testing is not being affected, assurance that containment integrity is maintained can also be performed by the performance of these tests.

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4 BASIS:

As discussed in the following sections, the requested exemption meets the three necessary criteria of 10 CFR 50.12(a)(1). In addition, there are special circumstances present which qualify for consideration for an exemption per the criteria established in 10 CFR 50.12(a)(2).

A. Criteria for Granting Exemption is met per 10 CFR 50.12(a)(1):

1. The Requested Exemption and the Activity which would be allowed thereunder are authorized by law.

If the criteria established in 10 CFR 50.12(a) are satisfied, as they are in this case, and if no other prohibition of law exists to preclude the activities which would be authorized by the requested exemption, and there are no such prohibitions, the) Commission is authorized by law to grant this exemption request. 1

2. The requested exemption will not present undue risk to the public As stated in 10 CFR 50, Appendix J, the purpose of primary containment leak rate testing is to ensure that the leakage through primary containment shall not exceed the leakage allowed by the Technical Specifications or associated bases and to ensure that I periodic surveillance is performed so that proper maintenance and repair is performed throughout the service life of the containment boundary components.

The two programs, the containment Type A tests and the ISI, are unrelated to one another and could be performed irrespective of one another. The purpose of requiring the third Type A test during the .

ISI 10-year plant inspection is apparently to assure that the three Type A tests are not " bunched" together. However, linking the Type A test with the unrelated ISI at 10 years is unrelated to ensuring the-containment leakage rates are within their limits.

Changing the time basis from the ISI 10-year service period to that of any ten year period does not affect the assurance that containment integrity is maintained. The Type A tests will continue to be conducted at approximately equal intervals which is consistent with l the current rule. The periodicity is consistent with the periodicity Unit I has maintained to present.

l l The containment will continue to be demonstrated to maintain its design function; to limit leakage rates to within the values specified in the Technical Specifications. The manner in which the Type A test is performed is not being altered nor the acceptance .

criteria For the test, 1, see U.S. vs. Alleghany-Ludium Steel Corp., 406 U.S. 742,755 (1972). s l

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1 The Type B and C testing is not being altered in any way. Since the most likely leakage through containment is via penetrations and valves, the performance of Type B and C testing assures that containment integrity is maintained.

Based on the above discussions, this exemption will not impose any undue risk to the health and safety of the public.

3. The requested exemption will not endanger the common defense and security The common defense and security are not in any way compromised by this exemption request. The proposed change does not alter the physical plant in any manner. -

At least one of the Special Circumstances are Present per 10 CFR 50.12(a)(2):

1. Application of the regulation in the particular circumstances is not necessary to achieve the underlying purpose of the rule.

The underlying purpose of the rule is to ensure that 1) the leakage rate through the containment does not exceed the allowable leakage rate values of the Technical Specifications and 2) periodic surveillance is performed so that proper maintenance and repairs are made during the service life of the containment.Section III.D.I (a) requires the performance of three Type A tests at approximately equal intervals during each 10-year service period, with the third test of the set being conducted at the same time as the 10 year 151. The completion of these three tests at approximately equal intervals over the 10 year period provides the assurance of primary containment integrity to meet the intent of the rule. However, coupling the Type A test schedule to the 10-year inservice inspection schedule is not necessary to meet the underlying purpose of the rule. Alternatively, '

containment integrity can be assured by completing three approximately equally spaced Type A tests over any ten year period.

Untoupling of the ISI and Type A test schedules is recognized by the NRC's proposed revision to 10 CFR 50 Appendix J (51 FR 39536, October 29, 1986).

Linkage of the ISI service period and schedule to that of '.he Type A test schedule for no apparent safety-related purpose would require Zion Unit I to perform Type A tests during consecutive refueling outages and only 19 months apart. Given the above discussion, application of the regulation in this circumstance is not necessary to achieve the underlying purpose of the rule which is namely to perform leak rate tests at approximately equal intervals throughout the life of the plant to assure that conta'nment integrity is being maintained.

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