ML20236C514
| ML20236C514 | |
| Person / Time | |
|---|---|
| Site: | Seabrook  |
| Issue date: | 03/15/1989 |
| From: | George Thomas PUBLIC SERVICE CO. OF NEW HAMPSHIRE |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NYN-89027, NUDOCS 8903220191 | |
| Download: ML20236C514 (4) | |
Text
{{#Wiki_filter:_ _. George S. Thomas { Vice President Nuclear Production ) Pubile Service of New Hampshire NYN 89027 l New Hampshire Yankee Division March 15, 1989 United States Nuclear Regulatory Commission 'l Washington, DC 20555 Attention: Document Control Desk
References:
(a) Facility Operating License NPF-56, Docket No. 50-443 (b) PSNH letter NYN-88161 dated December 15, 1988, "ATWS Mitigation System," G. S. Thomas to USNRC 1 1
Subject:
ATWS Mitigation System i Gentlemen: During a February 16, 1989, telephone conversation with representatives of i New Hampshire Yankee (NHY), the NRC Staff requested additional information with regards to the Seabrook Station ATWS Mitigation System (AMS). The following provides the requested information and clarifies information previously provided by Reference (b). l 0 A block diagram of the AMS showing the interfaces with plant systems is provided as an enclosure to this letter. The AMS logic cabinet has been purchased from SAIC. It utilizes analog devices for the bistables, and the logic is performed by programmable logic devices. The Reactor Protection System (RPS) was supplied by Westinghouse and utilizes analog bistables and solid state logic. Diversity between the RPS and the AMS is fulfilled by using equipment from different manufacturers. Power for the AMS logic cabinet will be frm a non-safety-related 125VDC l distribution panel powered by a non-cafety-related battery. The power to the battery charger for this battery is a non-safety-related 480 Volt Motor Control Center. The battery is sized such that it is capable of supplying its loads for at least 2 hours following a loss of power The AMS actuation time delay (TD 1) has been conservative aet at approximately 12 seconds based on a plant specific review. This will ensure that the AMS responds within the response time requirement of tne { Westinghouse generic design. 8903220191 890315 PDR ADOCK 05000443 0 P PDC \\ \\ i P.O. Box 300. Seabrook, NH 03874. Telephone (603) 474-9574 =
O-e. United States Nuclear Regulatory Commission March 15,1989
- Attention:
Document Control Desk Page 2 As shown on the block diagram, the AMS operating' bypass time delay (TD.2). will be in place for 360 seconds following turbine power dropping below 40% l power. i As shown on the block diagram, a time delay (TD 3)'of 60 seconds'was included in the design to ensure that the AMS actuation signal would remain energized long enough for the valves supplying steam to the turbine-driven Emergency Feedwater (EFW). pump to fully open. Sixty seconds provides enough tLne for these valves to reach their full open position and is consistent with the response time of the EFW System. The Class 1E to non-Class 1E interface.is shown in the block diagram. Periodic testing of the AMS logic cabinet will be performed upon installation and every two months thereafter for the first six months after it is installed. This testing will identify any possible early failures. Thereafter, the logic cabinet will be tested during plant refueling outages. This is consistent with vendor recommendations. System testing will be done either as a series of overlapping tests or as an integrated test from the inputs through and including the final actuating device. This testing will also be performed during refueling outages.- l Additionally, it should be noted that the Seabrook JMS is essentially l identical to the systems approved for Wolf Creek and.Callaway. Should you have further questions regarding this matter, please contact Mr. Richard R. Belanger at (603) 474-9574, extension 4048. Very truly.yours,. !.A Y h George S. Thomas l l Enclosure l cci Mr. William T. Russell Regional Administrator United States Nuclear Regulatory Commission Region I 475 Allendale Road King of Prussia, PA 19406 Mr. Victor Nerses, Project Manager Project Directorate I-3 United-States Nuclear Regulatory Commission Division of Reactor Projects Washington, DC 20555 Mr. David G.' Ruscitto NRC Senior Resident Inspector P.O. Box 1149 Seabrook, NH 03874
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