ML16342C992

Discusses Review of Proposed Emergency TS Change for Plant Unit 2.Request Schedule Submittal within 30 Days in Order to Comply w/10CFR50.46(a)(3)(ii)

ML16342C992
Person / Time
Site:	Diablo Canyon
Issue date:	07/24/1995
From:	Mark Miller NRC (Affiliation Not Assigned)
To:	Rueger G PACIFIC GAS & ELECTRIC CO.
References
TAC-M91845, TAC-M91846, NUDOCS 9507310263
Download: ML16342C992 (8)

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+ y**W UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 July 24, 1995 Mr. Gregory M. Rueger Nuclear Power Generation, B14A Pacific Gas and Electric Company 77 Beale Street, Room 1451 P. 0.

Box 770000 San Francisco, California 94106

SUBJECT:

DIABLO CANYON NUCLEAR POWER PLANT, UNIT NOS.

1 AND 2 COMPLIANCE WITH

'10 CFR 50.46 REQUIREMENTS (TAC NOS.

M91845 AND M91846)

Dear Mr. Rueger:

During its revi,ew of a proposed emergency technical specificati'on change for Diablo Canyon Nuclear Power Plant (DCPP), Unit 2, dated March 23,

1995, the'RC staff was referred to a letter submitted by the Pacific Gas and Electric Company (PG&E) on October 4, 1991.

In that letter, PG&E states that although changes in peak cladding temperature (PCT) resulted from License Amendments 65 and 64 for Units 1

and 2, respectively, PG&E had demonstrated compliance with 10 CFR 50.46, and that, therefore, reanalysis for loss-of-cooling accidents (LOCAs) is not necessary.

PG&E, in the October 4, 1991, submittal and in subsequent reports of changes in PCT, h'as performed an "assessment" of the impact of analysis changes on PCT.

Section 50.46(a)(3)(i) provides that licensees shall estimate the effect of any change to an acceptable evaluation model to determine if it is "significant," which is defined as a change resulting in a calculated PCT more than 50'F different from the'temperature calculated for the limiting transient using the last acceptable model, or a cumulation of errors and changes whose sum of absolute values of the temperature changes exceed 50'F.

Section 50.46(a)(3)(ii) provides that for each significant change in an acceptable evaluation model that affects the temperature calculation, the licensee shall report the change and its estimated effect on the limiting emergency core cooling system (ECCS) analysis within 30 days, and shall include with the report "a proposed schedule for providing a reanalysis or for taking other action as may be needed to show compliance with 550.46 requirements."

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Enclosure 1 to the October 4, 1991, letter, and its attachment indicate that PG&E's small-break LOCA assessment showed an increase of 58'F in PCT from the last assessment, the cumulative sum of the absolute values of several changes to the assessed PCT was 247'F, and that the calculated net effect of all changes identified in the October 4 letter resulted in an assessed PCT of less than the 2200'F limit specified in 10 CFR 50.46(b)(1).

PG&E states that because Enclosure 1 of the October 4 letter documents the PCT changes as a

result of License Amendments 65 and 64 for Units 1 and 2, respectively, and since the resulting PCT value is still well below the 10 CFR 50.46 limit of 2200'F, it has demonstrated compliance with 10 CFR 50.46 and that there is no requirement to perform a reanalysis.

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Hr. Rueger Ouly 24, 1995 Section 50.46(a)(l)(i) requires the calculation of ECCS cooling performance in accordance with an acceptable evaluation model.

However, the estimated PCT adjustments made for DCPP, Units 1 and 2, to determine the new estimated PCT were made using methods not reviewed and approved by the NRC.

Horeover, the PCT resulting from PG&E's assessment of multiple changes is inherently imprecise.

The 58'F increase in PCT, and the cumulative sum of changes of 247'F discussed in the October 4 letter, are both "significant" changes within the plain meaning of 10 CFR 50.46(a)(3)(i).

As provided by 10 CFR 50.46(a)(3)(ii), the imprecisions associated with such significant changes require PG&E to submit not only a report of the significant changes and their estimated effects on the ECCS limiting analysis, but also a proposed schedule for either of two options:

(1) performing a reanalysis or (2) taking other action to show compliance with Section 50.46.

PG&E may take other action such as reconfiguring the plant so that it again is consistent with assumptions used in the licensing basis analysis performed with the evaluation model reviewed and accepted by the NRC.

In order to comply with 10 CFR 50.46(a)(3)(ii), please submit a schedule, within 30 days of the date of this letter, for,providing a reanalysis or for taking other action (and describing that action) as may be needed to show compliance with the requirements of 10 CFR 50.46.

The requirement affects nine or fewer respondents and, therefore, is not subject to the Office of Hanagement and Budget review under P.L.96-511.

If you have any questions, please contact me at (301) 415-1323.

Sincerely, Helanie A. Hiller, Senior Project Hanager Project Directorate IV-2

, Division of Reactor Projects III/IV

'ffice of Nuclear Reactor Regulation Docket Nos.

50-275 and 50-323 cc:

See next page-DOCUHENT NAHE:

DC91845.LTR DISTRIBUTION:

Docket File PUBLIC PDIV-2 Reading JRoe EAdensam RJones WBateman EPeyton ACRS (4)

OGC, 15B18

KPerkins, RIV/WCFO OFC PDIV-2 LA EfeyCS PDIV-2/PH OGC NRR:SRXB RJones DATE 7

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Mr. Gregory M. Rueger CC:

NRC Resident Inspector Diablo Canyon Nuclear Power Plant c/o U.S. Nuclear Regulatory Commission P. 0.

Box 369 Avila Beach, California 93424 Dr. Richard Ferguson, Energy Chair Sierra Club California 6715 Rocky Canyon

Creston, California 93432 Ms. Nancy Culver San Luis Obispo Mothers for Peace P. 0.

Box 164 Pismo Beach, California 93448 Ms. Jacquelyn C. Wheeler P. 0.

Box 164 Pismo Beach, California 93448 Managing Editor The Count Tele ram Tribune 1321 Johnson Avenue P. 0.

Box 112 San Luis Obispo, California 93406 Chairman San Luis Obispo County Board of Supervisors Room 370 County Government Center San Luis Obispo, California 93408 Mr. Truman Burns Mr. Robert Kinosian California Public Utilities Commission 505 Van Ness, Room 4102 San Francisco, California 94102 Mr. Steve Hsu Radiologic Health Branch State Department of Health Services Post Office Box 942732 Sacramento, California 94232 Regional Administrator, Region IV U.S, Nuclear Regulatory Commission Harris Tower 5 Pavillion 611 Ryan Plaza Drive, Suite 400 Arlington, Texas 76011-8064 Mr. Peter H. Kaufman Deputy Attorney General State of California 110 West A Street, Suite 700 San Diego, California 92101 Christopher J.

Warner, Esq.

Pacific Gas

& Electric Company Post Office Box 7442 San Francisco, California 94120 Mr. Warren H. Fujimoto Vice President and Plant Manager Diablo Canyon Nuclear Power Plant P. 0.

Box 56 Avila Beach, California 93424 Diablo Canyon Independent Safety Committee ATTN:

Robert R. Wellington, Esq.

Legal Counsel 857 Cass Street, Suite D

Monterey, California 93940

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Hr. Rueger Ouly 24, 1995 Section 50.46(a)(1)(i) requires the calculation of ECCS cooling performance in accordance with an acceptable evaluation model.

However, the estimated PCT adjustments made for DCPP, Units 1

and 2, to determine the new estimated PCT were made using methods not reviewed and approved by the NRC.

Moreover, the PCT resulting from PG&E's assessment of multiple changes is inherently imprecise.

The 58'F increase in PCT, and the cumulative sum of changes of 247'F discussed in the October 4 letter, are both "significant" changes within the plain meaning of 10 CFR 50.46(a)(3)(i).

As provided by 10 CFR 50.46(a)(3)(ii), the imprecisions associated with such significant changes require PG&E to submit not only a report of the significant changes and their estimated effects on the ECCS limiting analysis, but also a proposed schedule for either of two options:

(1) performing a reanalysis or (2) taking other action to show compliance with Section 50.46.

PG&E may take other action such as reconfiguring the plant so that it again is consistent with assumptions used in the licensing basis analysis performed with the evaluation model reviewed and accepted by the NRC.

In order to comply with 10 CFR 50.46(a)(3)(ii),

please submit a schedule, within 30 days of the date of this letter, for providing a reanalysis or for taking other action (and describing that action) as may be needed to show compliance with the requirements of 10 CFR 50.46.

The requirement affects nine or fewer respondents and, therefore, is not subject to the Office of Management and Budget review under P.L.96-511.

If you have any questions, please contact me at (301) 415-1323.

Sincerely, Melanic A. Hiller, Senior Project Manager Project Directorate IV-2 Division of Reactor Projects III/IV Office of Nuclear Reactor Regulation Docket Nos.

50-275 and 50-323 cc:

See next page NAME EPeyeS HHl

.y DOCUMENT NAME:

DC91845.LTR OFC PDIV-2 LA PDIV-2 PH DISTRIBUTION:

Docket File PUBLIC PDIV-2 Reading JRoe EAdensam OGC I

r RJones NRR:SRXB RJones~

WBateman EPeyton ACRS (4)

OGC, 15B18

KPerkins, RIV/WCFO DATE 7

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