ML20198F893

Informs That on 970304,San Onofre,Unit 2,pressurizer Vessel Experienced Cooldown Transient at Rate Greater than 200 F/Hr Limit Specified in Tss.Fracture Mechanics Evaluation of Pressurizer Transient Met Criteria in App G of ASME Code

ML20198F893
Person / Time
Site:	San Onofre
Issue date:	12/22/1997
From:	Wichman K NRC (Affiliation Not Assigned)
To:	Fields M NRC (Affiliation Not Assigned)
References
TAC-M98232, NUDOCS 9801120196
Download: ML20198F893 (3)

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• NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 30866 0001 l ,,,,, December 22, 1997 MEMORANDUM TO: Mel B. Fields, Project Manager Project Directorate IV 2 Division of Reactor Projects, lll & IV FROM: Keith R. Wichman, Chief Section A NSN Materials and Chemical Engineering Branch Division of Engineering

SUBJECT:

SAN ONOFRE PRESSURIZER RAPID COOLDOWN TRANSIENT Plant Name: San Onofre Unit 2 Licensee: Southem Califomia Edison TAC No.: M98232 Review Status: Complete On March 4,1997, the San Onofre Unit 2 pressurizer vessel experienced a cooldown transient at a rate greater than the 200'F/hr limit specified in the Technical Specifications.

The first teleconference with the NRC occurred on March 7,1997. The NRC staff informed the licensee that, because the transient resulted in cold water (T = 110'F) being injected into a hot pressurizer (T = 430'F), a brittle bacture evaluation was necessary During a second teleconferance on March 12,1997, the licensee indicated that they had performed a brittle fracture evaluation and that the fracture toughness during the transient satisfied the criteria in Appendix G of Section XI of the ASME Code. During a third teleconfcrence on March 13,1997, the staff requested that the licensee document their review prior to restart, and that the criteria used in the review (e.g.,1/4T 9aw) should be identified.

On the moming of March 14,1997, the licensee informed the staff that a 1/10T flaw was postulated because it could be supported by recent ultrasonic examination results. In order to determine the licensee's basis for concluding that a 1/10T flaw met the Appendix G criteria, a fourth teleconference was held on the aftemoon of March 14. The licensee explained that b.Q.itt a il4T and 1/10T flaw were postulated for the evaluation. The staff noted that this methodology had not been explained earlier that moming, and the licensee acknowledged that the information had not been clearkf expressed initially. The information discussed during the fourth teleconference indicated that the postulation of either the 1/4T or the 1/10T flaw met the criteria in Appendix G.

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M Fields._ - 2-t The licensee submitted information on March 14,1997, which described the transient and stated that the evaluation met the criteria in Appendix G of the ASME Code. Additionalinformation, including the details of the fracture mechanics evaluation was provided by letter dated -

May_1,1997.

The Materials and Chemical Engineering Branch of the Division of Engineering has completed its assessment of the pressurizer thermal transient. We have concluded that the fracture mechanics evaluation of the pressurizer transient at San Onofre Unit 2 met the criteria in Appendix G of the ASME Code. This completes our review efforts for TAC No. M98232.

Docket No.: 50 361 cc: W. Bateman

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The licensee submitted information on March 14,1997., which described the transient and stated that the evaluation met the criteria in Appendix G of the ASME Code. Additionalinformation, including the details of the fracture mechanics evaluation was provided by letter dated May 1,1997.

The Materials and Chemical Engineering Branch of the Division of Engineering has completed its assessment of the pressurizer thermal transient. We have concluded that the fracture

- mechanics evaluation of the pressurizer transient at San Onofre Unit 2 met the criteria in Appendix G of the ASME Code. This completes our review efforts for TAC No. M98232. .

Docket No.: 50-361 cc: W. Bateman DISTRIBUTION:

EJSullivan MCenhei!"?!

PUBLIC EMCB RF '

G:\ LEE \SANONOFR.WPD To receive a copy of this document, indicate in the box C= Copy w/o attachment / enclosure E= Copy with attachment / enclosure N = No copy ,l l*l '

OFFICE DE:EMCb. b DE:EMCB - C DE:EMCB C NAME ALea/fII BElliot @>Y KWichman Urh v

, DATE 12/hv97 12/W97 12/;h97 MlU-V i

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