ML20137L435

Forwards Request for Addl Info Re Pressurizer Thermal Transient

ML20137L435
Person / Time
Site:	San Onofre
Issue date:	04/03/1997
From:	Fields M NRC (Affiliation Not Assigned)
To:	Ray H SOUTHERN CALIFORNIA EDISON CO.
References
TAC-M98232, NUDOCS 9704070226
Download: ML20137L435 (4)

Text

. . . . . .

April 3,1997 Mr. Harold B. Ray Executive Vice President Southern California Edison Company San Onofre Nuclear Generating Station P. O. Box 128 San Clemente, California 92674-0128

SUBJECT:

REQUEST FOR INFORMATION REGARDING THE PRESSURIZER THERMAL TRANSIENT ON SAN ONOFRE NUCLEAR GENERATING STATION UNIT 2 (TAC NO. M98232)

Dear Mr. Ray:

During the recent shutdown of San Onofre Nuclear Generating Station Unit 2 to repair a small leak in. the pressurizer, the pressurizer cooldown rates exceeded the technical specification (TS) allowable cooldown rate of 200*F in any one hour period on March 4, 1997. Action A.1 of TS 3.4.3.1, " Pressurizer Heatup and Cooldown Limits," requires that an evaluation be performed to verify that the pressurizer is acceptable for continued operatien when the heatup or cooldown limits are exceeded. Such an evaluation was performed by your staff, and the results were provided to the NRC in a letter dated March 14, 1997.

Please provide a response within 30 days of the date of this letter to the enclosed request for additional information. Your response to these questions ~

will allow the staff to verify that the analysis performed in support of the March 14, 1997, letter satisfies the criteria in Appendix G of the ASME Code.

Sincerely, ORIGINAL SIGNED BY Mel B. Fields, Project Manager Project Directorate IV-2 Division of Reactor Projects III/IV Office of Nuclear Reactor Regulation Docket No. 50-361 DISTRIBUTION:

Docket File ACRS, TWFN

Enclosure:

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OFFICIAL RECORD COPY l I

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9704070226 970403 PDR ADOCK 05000361 P PDR

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NUCLEAR REGULATORY COV4ISSION-WASHINGTON, D.C. asseMcM

,,,,, April .3,1997 Mr.. Harold B.; Ray Executive Vice President Southern California Edison Company San Onofre Nuclear. Generating Station

- P. 0. Box 128 San Clemente, California92674-0128 -

SUBJECT:

REQUEST FOR INFORMATION REGARDING THE PRESSURIZER THERMAL TRANSIENT ON SAN _0NOFRE NUCLEAR GENERATING STATION UNIT 2 (TAC NO. M98232).

Dear Mr. Ra/:

During the recent shutdown of San Onofre Nuclear Generating Station Unit 2 to repair a small . leak in the pressurizer, the pressurizer cooldown rates exceeded the. technical specification (TS) allowable cooldown rate of 200*F in any one hour period on March 4, 1997. Action A.1 of TS 3.4.3.1, " Pressurizer

'Heatup and Cooldown Limits," requires that an evaluation be performed to verify that the pressurizer -is acceptable-for continued operation when the heatup or cooldown limits are exceeded. Such an evaluation was performed by your staff, and the results_were provided to the NRC in a letter dated.

March 14, 1997.

Please provide a response within 30 days of the date of this letter to the enclosed request for additional information. Your response to these questions will allow the staff to verify that the analysis performed in support of the  !

March 14, 1997, letter satisfies the criteria in Appendix G of the ASME. Code. l Sincerely, ' -

W A FA AN Mel B. Fields, Project Manager Project Directorate IV-2 Division of Reactor Projects III/IV Office. of Nuclear Reactor Regclation Docket No. 50-361

Enclosure:

- Request for Additional Information cc w/ enc 1: See next page I

f l . . , . .

i 1

. Mr. Harold B. Ray cc w/ encl:

Mr. R. W. Krieger, Vice President Resident Inspector / San Onofre NPS

' Southern California Edison Company c/o U.S. Nuclear Regulatory Commission San Onofre Nuclear Generating Station Post Office Box 4329 P. O. Box 128 San Clemente, California 92674

. San Clemente, California 92674-0128 Mayor  ;

Chairman, Board of Supervisors City of San Clemente '

County of San Diego 100 Avenida Presidio 1600 Pacific Highway, Room 335 San Clemente, California -92672 San Diego, California 92101 Alan R. Watts, Esq.

Woodruff, Spradlin & Smart 701 S. Parker St. No. 7000

!. Orange, California 92668-4702 Mr. Sherwin Harris i Resource Project Manager i Public Utilities Department City of Riverside 3900 Main Street Riverside, California 92522 Dr. Harvey Collins, Chief t Division of Drinking Water and Environmental Management California Department of Health Services P. O. Box 942732 Sacramento, California 94234-7320 - l Regional Administrator, Region IV i U.S. Nuclear Regulatory Commission Harris Tower & Pavilion 611 Ryan Plaza Drive, Suite 400  ;

Arlington, Texas 76011-8064 Mr. Terry Winter i Manager, Power Operations San Diego Gas & Electric Company P.O. Box 1831 San Diego, California 92112-4150 Mr. Steve Hsu Radiologic Health Branch State Department of Health Services Post Office Box 942732 Sacramento, California 94234

s RE0 VEST FOR ADDITIONAL INFORMATION SAN ON0FRE NUCLEAR GENERATING STATION UNIT 2 PRESSURIZER STRUCTURAL INTEGRITY ANALYSIS DOCKET NO. 50-361

1. Using the reported reference temperature (RT ,) of 60'F for the surge ,

nozzleforging,a1/4 thickness (1/4T)deephawandthethermal i transient that represents the cooldown of the surge nozzle, provide the following information at a sufficient number of time increments in the transient to demonstrate that the surge nozzle will meet the Appendix G criteria for the entire transient: ,

l (a) the values of the primary membrane stresses due to pressure,  ;

l (b) the values of the thermal stress due to the thermal gradient, I l

(c) the values of the membrane stress intensity fcctor, l (d) the values of the thermal stress intensity factor, (e) the temperatures of the surge nozzle at the 1/4T location, and (f) the values of the reference stress intensity factor (K ,) at the 3

1/4T location.

1

2. Describe the stress analysis and the method of converting the stresses -

into stress intensity factors. i l

3. Provide the basis for the conclusion that the deepest postulated flaw should be a 1/10T. As justification for this assumption provide the l following information:

(a) the volume of the surge nozzle inspected, (b) the method of inspection of the surge nozzle, (c) the results from the qualification demonstration for the inspectors, the equipment, and the procedures, and (d) the probability of detection (POD) of a 1/10T flaw based on the qualific.ation of the inspectors, equipment and procedures.