Difference between revisions of "ML20071N899"

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Requests Correction on First Quarter 1993 Performance Indicator Rept for SONGS Units 2 & 3.Listed Event Re Anomaly in Core Protection Calculator Should Be Reclassified & Not Be Identified as Significant Event in Future Repts
Person / Time
Site: San Onofre Southern California Edison icon.png
Issue date: 08/03/1994
From: Marsh W
Download: ML20071N899 (2)


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  1. . j f "$ 5 Southem Califomia Edison Company 7'3 PAHKr H ST REET 4HVINE. CAL WOHNIA 92718 wAt u n c mnsn August 3, 1994 m.,._, '

MANAGF Fu (W tetK.t i Art 74EulA A TOMY AF F A46tB (714) Ab4 4403 U. S. Nuclear Regulatory Commission Attention: Document Control Desk 1 Washington, D.C. 20555 I Gentlemen: l


Docket Nos. 50-361 and 50-362 Request for Correction of the Quarterly Performance Indicator Report San Onofre Nuclear Generating Station Units 2 and 3 This is a request that the Nuclear Regulatory Commission Office for Analysis and Evaluation of Operational Data (AE0D) correct the quarterly Performance Indicator Report for San Onofre Units 2 and 3.

Recent issues of the Performance Indicator Report have included a Significant Event for both San Onofre Unit 2 and San Onofre Unit 3 in the first quarter of 1993. This event was described in the report as follows:

Because of a power distribution modeling error, DNB ratios calculated by the Core Protection Calculator were nonconservative !

over several fuel cycles. This error would have prevented the I actuation of a DNBR trip signal at the desired setpoint. l t

The report is referring to an event which occurred in February 1993. As a l result of Southern California Edison (Edison) core follow activities, an '

anomaly was discovered in the Core Protection Calculator'(CPC) synthesized i axial power shapes. Specifically, the CPC channels were generating " cosine ',

type" axial shapes while incore instrument measured and predicted shapes had changed to " saddle type." Edison performed an in-depth evaluation of the root l cause of the CPC synthesized anomalous shape and forwarded the root cause report to the NRC in a letter dated July 19, 1993.

1 Included as an appendix to our root cause report was a letter from ABB !

Combustion Engineering (CE) which addressed the operability of the CPC l channels for San Onofre Units 2 and 3 fuel cycles 3, 4, 5, and 6. In this l letter, ABB CE concluded that the CPCs were operable during these cycles and that "overall operation of the SONGS CPCs was deemed conservative and within the current SONGS analysis of. record for UFSAR events."

l Based on the ABB CE evaluation, the characterization of this event in the !

Performance Indicator Report is not correct, and furthermore, this event Q.

00 M$g61 ' D, PDR

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. Document Control Desk should not be classified as a Sign.'ficant Event for San Onofre Units 2 and 3.

It is therefore requested that this event be reclassified and not be identified as a Significant Event in future issues of this report.

If you wish to discuss this issue further, please call me.


[h0 cc: L. J. Callan, Regional Administrator, NRC Region IV K. E. Perkins, Jr., Director, Walnut Creek Field Office, NRC Region IV J. A. Sloan, NRC Senior Resident Inspector, San Onofre Units 2 & 3 M. B. Fields, NRC Project Manager, San Onofre Units 2 and 3 t






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