ML20028G301

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Informs of Change in Specific Pump Trip Criteria Per IE Bulletin 79-05C.Use of Pump Trip Criteria Will Be Implemented W/Implementation of Emergency Operating Procedures as Part of TMI Item I.C.1
ML20028G301
Person / Time
Site: Arkansas Nuclear Entergy icon.png
Issue date: 01/31/1983
From: John Marshall
ARKANSAS POWER & LIGHT CO.
To: Stolz J
Office of Nuclear Reactor Regulation
References
RTR-NUREG-0737, RTR-NUREG-737, TASK-1.C.1, TASK-TM ICAN018307, ICAN18307, IEB-79-05C, IEB-79-5C, NUDOCS 8302070609
Download: ML20028G301 (2)


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ARKANSAS POWER & LIGHT COMPANY POST OFFICE BOX 551 UTTLE ROCK. ARKANSAS 72203 (501) 371-4000 January 31, 1983 1CAN018307 Director of Nuclear Reactor Regulation ATTN: Mr. J. F. Stolz, Chief Operating Reactors Branch #4 Division of Licensing U. S. Nuclear Regulatory Commission Washington, DC 20555

SUBJECT:

Arkansas Nuclear One - Unit 1 Docket No. 50-313 License No. DPR-51 IE Bulletin 79-05C - Commitments Gentlemen:

As required by IE Bulletin 79-05C, AP&L took steps to insure that Reactor Coolant Pumps (RCP's) at ANO would be immediately tripped upon reactor trip and subsequent HPI initiation. This requirement was based on industry analyses which showed (for a narrow range of break sizes) that if the pumps remained running while the system evolved to a high void fraction, subsequent tripping of the pumps might result in uncovery of the reactor core. This uncovery would be due to void collapse and could lead to inadequate core cooling.

AP&L remains committed to tripping the RCP's under certain accident situations; however, we do not believe that HPI initiation is the best of the currently available alternatives. Because the concerns over tripping of the RCP's are due to the formation of voids in the reactor coolant system, we believe that tripping the pumps upon loss of subcooling margin is a more reliable and practical criteria, and also addresses the main phenomenon of interest, i.e., void formation.

Therefore, while we continue in our commitment to trip the RCP's in line with the intent of Bulletin 79-05C, this letter is submitted to inform you that AP&L is changing the specific pump trip criteria for ANO-1.

Specifically we are adopting the criteria for tripping the RCP's upon loss of the subcooling margin. The margin above saturation was determined by AP&L and includes all relevant instrument uncertainties (such as accuracy, calibration, etc.). Use of this pump trip criteria will be implemented in conjunction with implementation of the ANO emergency operating procedures developed as part of AP&L's response to NUREC-0737 Item I.C.1. Use of the 8302070609 830131 PDR ADOCK 05000313 etvorn vcote soum uTitmos svsrev

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l Mr. J. F. Stolz January 31, 1983 i l

4 subcooling margin has been discussed with NRC personnel several times in informal meetings dating back to August 1980; however, because of our previoas formal commitments to trip the RCP's upon HPI initiation, this letter is necessary to formally notify you of our change in criteria.

Very truly yours, yJo,hn R. Marshall Mancsger, Licensing JRM:CHT:sc i

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