ML063610042

Additional Information in Support of Amendment Application Numbers 243 and 227

ML063610042
Person / Time
Site:	San Onofre
Issue date:	12/22/2006
From:	Scherer A Southern California Edison Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
TAC MD1405, TAC MD1406
Download: ML063610042 (4)

Text

JSOUTHERN CALIFORNIA EDISON An EDISON INTERNATIONALS Company A. Edward Scherer Manager of Nuclear Regulatory Affairs December 22, 2006 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001

Reference:

Docket Nos. 50-361 and 50-362 Additional Information in Support of Amendment Application Numbers 243 and 227 (TAC Nos. MD1405 and MD1406)

San Onofre Nuclear Generating Station, Units 2 and 3

1)

Letter from N. Kalyanam (NRC) to Richard M. Rosenblum (SCE) dated October 26, 2006;

Subject:

San Onofre Nuclear Generating Station, Units 2 and 3 - Request for Additional Information on the Proposed Amendment to Revise Fuel Storage Pool Boron Concentration (TAC Nos. MD1405 and MD1406)

2)

Letter from A. E. Scherer (SCE) to the U.S. Nuclear Regulatory Commission (Document Control Desk) dated November 13, 2006;

Subject:

Docket Nos. 50-361 and 50-362 Additional Information in Support of Amendment Application Numbers 243 and 227 (TAC Nos.

MD1405 and MD1406) San Onofre Nuclear Generating Station, Units 2 and 3

Dear Sir or Madam:

This letter provides the second of two Southern California Edison (SCE) responses to the October 26, 2006 U.S. Nuclear Regulatory Commission (NRC) Staff request for additional information (Reference 1). In the Reference 1 letter, the NRC asked two questions, SCE answered the first question by letter dated November 13, 2006 (Reference 2).

Enclosed is the SCE response to the second question.

P.O. Box 128 San Clemente, CA 92672 949-368-7501 Fax 949-368-7575

Document Control Desk December 22, 2006 Should you have any questions, please contact Ms. Lynn Pressey at 949-368-6351.

Sincerely,

Enclosure:

As stated cc:

B. S. Mallett, Regional Administrator, NRC Region IV N. Kalyanam, NRC Project Manager, San Onofre Units 2 and 3 C. C. Osterholtz, NRC Senior Resident Inspector, San Onofre Units 2 and 3

Southern California Edison (SCE)

San Onofre Nuclear Generating Station (SONGS), Units 2 and 3 Docket Nos. 50-361 and 50-362 Enclosure Responses to NRC Staff Questions Regarding Proposed Change Notice (PCN) 556

Responses to NRC Staff Questions Regarding Proposed Change Notice (PCN) 556 NRC Question:

Given the many dilution paths mentioned, describe how the 7 day surveillance interval is adequate to detect slow boron dilution events. In particular, address the case where unborated makeup is provided for a small (1 -2 gpm) leak that may be overlooked as an unusual condition and processed through radwaste or be otherwise undetected.

SCE Response:

Normal spent fuel pool operation at the San Onofre Nuclear Generating Station does not include an automatic fill system from either a borated or an unborated source of water. Thus, the proposed scenario would be concurrent leaks into and out of the spent fuel pool at the same rate, such that spent fuel pool level would not change.

Based on this scenario, a slow boron "feed and bleed" dilution on the order of 1-2 gpm would be detectable in the 7 day surveillance, as the corresponding SFP dilution would result in boron concentration at least approximately 40 - 80 ppm lower than during the previous surveillance and the tolerance of the chemistry boron measurement is +/- 0.3% (less than +/-9 ppm).

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