05000423/LER-1996-029, Forwards Revised Commitments That Were Previously Submitted to NRC in LER 96-029-00, Functional Deficiency in Setting of ECCS Throttle Valve Positions

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Forwards Revised Commitments That Were Previously Submitted to NRC in LER 96-029-00, Functional Deficiency in Setting of ECCS Throttle Valve Positions
ML20211F076
Person / Time
Site: Millstone Dominion icon.png
Issue date: 09/18/1997
From: Hicks G
NORTHEAST NUCLEAR ENERGY CO.
To:
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
B16709, NUDOCS 9709300339
Download: ML20211F076 (4)


LER-2096-029, Forwards Revised Commitments That Were Previously Submitted to NRC in LER 96-029-00, Functional Deficiency in Setting of ECCS Throttle Valve Positions
Event date:
Report date:
4232096029R00 - NRC Website

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Suritet Nwlear lincery Coinpany P.R 110 128 Waterli.rd, Ur 46'1h5 0128 (800) 447 1741 l'an (860) 444 4277 ne Nortlea.t li ihneet $ptem Docket No. 50-423 B16709 September 18.1997 U. S. Nuuear Regulatory Commission Attention: Document Control Desk Washington, DC 20555 Millstone Nuclear Power Station, Unit No. 3 Commitment Revision - LER 96-029 00 Installation of Restrictive Orifices in Selected ECCS Branch Lines The purpose of this letter is to revise the commitments that were previously submitted to the NRC in LER 96-029-00, *FunctionalDeficiencvin the Settina of the Emeraency Core Coolina System Throtti.e_ Valve Positions". These commitments included; 1)

  • Install restrictive orifices in selected ECCS branch lines to relieve the throttling burden on the branch line throttling valves, permitting the valves to be set in more open positions while still satisfying the minimum required deliverable flows during the injection phase and recirculation phase. Additionally, install restrictive orifices in the suction supply headers to the CHS pumps from the RSS pumps to mitigats RSS pump boost" and; 2)" Maintain the plant in Mode 5 or lower until such time as modification to the suction supply headers to the CHS pumps from the RSS pumps have been completed and restrictive orifices have been installed in each ECCS branch line."

The potential high head Emergency Core Cooling System (ECCS) pump runout during post Loss Of Coolant Accident (LOCA) recirculation due to Containment h

Recirculation Spray System (RSS) pump boost effect was analyzed using a detailed pg computer model. This analysis showed that the addition of restrictiveorificesin selected ECCS branch lines to relieve the throttling burden on the branch line throttling valves, combined with adjustment of throttle valve position and testing would ensure safe long term operation during Post LOCA recirculation. Based on this analysis,it was determined that the installation of restrictive orifices in the suction supply headers to the Charging System (CHS) pumps from the RSS pumps was not required to mitigate RSS pump boost.

Therefore, the portions of the commitments pertaining to installation of restrictive orifices in the suction supply headers to the CHS pumps from the RSS pumps to mitigate RSS pump boost are no longer applicable. The revised commitments are S PDr hl,lklhlll '

1).S. Nucle:r Regulatory Commission B16709\ Page 2

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provided in Attachment 1. The remaining commitments in our letter of September 27,1996 are unchanged.

Should you have any questions regarding this matter, please contact Mr. D. A. Smith at (860) 437 5840.

NORTHEART MIir' LEAR ENERGY COMPANY

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Director - Millstone Unit No. 3 cc: H. J. Miller, Region I Administrator A. C. Cerne, Senior Resident inspector, Millstone Unit No. 3 J. W. Andersen, NRC Project Manager, Millstone Unit No. 3 W. D. Travers, Dr., Director, Special Projects 4

Docket No. 50-423 B16709 Attachment 1 Millstone Nuclear Power Station, Unit No. 3 NNECO's Commitments In Response To (LER 96-029-00)

September 1997

  • , U.S. Nucle:r R:gulatory Commission
  • B1670g \ Att:chment 1 \ Page 1 Enclosure List of Regulatory Commitments The following table identifies those actions committed to by NNECO in this document. Please notify the Manager Nuclear Licensing at the Millstone Nuclear Power Station Unit No. 3 of any questions regarding this document or any associated regulatory commitments.

Numuer Commitment Due B15890-01: Install restrictive orifices in selected ECCS ~ Prior to entry into branch lines to relieve the throttling burden Mode 4 on the branch line throttling valves, permitting the valves to be set in more open positions while still satisfying the minimum required deliverable flows during the injection phase and recirculation phase and preventing pump _ run out when subjected to RSS pump boost.

B15890-02 Maintain the plant in Mode 5 or lower until N/A such time as restrictive orifices have been installed in selected ECCS branch line and the throttling valves have been balanced to meet Technical Specification requirements.

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