3F1091-17, Suppls 910613 & 0703 Responses to NRC Supplemental Safety Evaluation Re Station Blackout Rule Implementation.Inverter Test Rept from Solidstate Controls,Inc Documents Successful Completion of Two 8 H Tests

Suppls 910613 & 0703 Responses to NRC Supplemental Safety Evaluation Re Station Blackout Rule Implementation.Inverter Test Rept from Solidstate Controls,Inc Documents Successful Completion of Two 8 H Tests

ML20085L528
Person / Time
Site:	Crystal River
Issue date:	10/28/1991
From:	Beard P FLORIDA POWER CORP.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
3F1091-17, NUDOCS 9111040205
Download: ML20085L528 (2)

Text

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Florida Power CORPOAA1*ON l Crystal River Unit 3 l Docket no ' + 302 1

% l October?AI1991 3fl091-17 l V. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C. 20555

Subject:

Station Blackout Rule implementation

Reference:

A. NRC to FPC letter dated May 6, 1991  !

B. FPC to NRC letter dated June 13, 1991 l C. FPC to NRC letter dated July 3, 1991 l

Dear Sir:

l This letter provides additional information in response to the NRC Staff's  !

Siipplemental Safety Evaluation (Reference A) regarding station blackout rule implementation for Crystal River Unit 3 (CR-3). The SER identified five open i issues. Three of the issues were addressed by Reference B. Reference B also contained a commitment on a fourth issue to provide the additional information being provided by this letter related to the operability of the inverters. The fifth issue (Reactor Coolant System Inventory) was addressed in Reference C.

In Reference A, the NRC Staff expressed their concerns regarding the operability of the inverters for a station blackout event as follows:

"The staff does not consider an Arrhenius analysis appropriate, unless substantiated by test results, for assessing the operability of inverters at temperatures substantially above their dasign or qualified temperature.

Although NUMARC 87-00, Appendix F, notes that a margin above the continuous rating of the equipment may exist, it specifically notes that margins are smaller for electronic equipment than electromechanical devices. NUMARC 87-00 does not suggest that an Arrhenius methodology is appropriate for determining this margin. The staff is concerned that a sudden failure, not an aging type failure, would occur for an inverter whta it reaches temperatures substantially above its qualified rating. The licensee must resolve this concern by, for example, providing appropriate cooling to the inverters, or demonstrating by test that the inverters will not fail at the expected temperature plus a reasonable margin."

(h 9111040205 ^110 J I b DR ADOCV 0000 2 A Florica Progress Company l i

l U.'S, Nuclear Regulatory Commission

, October 2X,41991 3fl091-17 Page 2 in response to the NRC Staff concerns, IPC has performed an industry search and obtained a copy of a test report for a similar inverter manuf actured by the same vendor (Solidstate Controls, Inc.) as the inverters at CR-3. The report documents the successf ul completion of 2 tests of 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> each at a temperature in excess of the temperatur calculated in the most recent revision of the inverter room heat up calcu' .n . lhe applicability of the test report to the inverters at CR-3 has br <, t This evaluation revealed that the part numbers, materials, a n< > " he electronic components in the tested inverter are similar to , 'o the CR-3 Inverters. As a result the test report is applicable 'rters as well.

As a result of this test ren ions of the applicability review, FPC considers the documentatiu.; m be fully responsive to the NRC concerns and provides adequate ju- - the operability of the inverters for the four hour station blackout event. ' u documentation is available for NRC Staff review.

This is FPC's final submittal in response to the Supplemental safety Evaluation and, in combination with References B and C, should provide sufficient information for the NRC Staff to conclude Crystal River 3 is in compliance with the Station Blackout Rule (10 CFR 50.63).

Sincerely, q tw.sl P. M. Beard, Jr.

Senior Vice President Nuclear Operations PMB/AEF:ff xc: Regional Administrator, Region 11 NRR Project Manager Senior Resident inspector

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