ML20138C854
| ML20138C854 | |
| Person / Time | |
|---|---|
| Site: | Callaway  |
| Issue date: | 10/14/1985 |
| From: | Schnell D UNION ELECTRIC CO. |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| GL-85-06, GL-85-6, ULNRC-1189, NUDOCS 8510230067 | |
| Download: ML20138C854 (3) | |
Text
.
aan UNION ELECTINC COMPANY 1901 Gratiot Street. St. Louis October 14, 1985 Donald F. Schnell Vice President Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D.C.
20555
Dear Mr. Denton:
ULNRC-1189 DOCKET NUMBER 50-483 CALLAWAY. PLANT, UNIT 1 RESPONSE TO FINAL RULE ON 10CFR50.62 - ATWS MITIGATION
Reference:
Generic Letter 85-06 dated April 16, 1985 On June 1, 1984 the Commission approved 10CFR50.62, regarding the reduction of risk from anticipated transients without scram (ATWS) events for light-water cooled nuclear power plants.
Section 50.62 (d) requires each licensee to. develop and submit to the Director of the Office of Nuclear Reactor Regulation a proposed schedule for meeting the requirements of the rule.
The purpose of this letter is to provide a proposed schedule for meeting the requirements of the ATWS rule.
Section 50.62 (c) (1) of the Code of Federal Regulations requires each pressurized water reactor (PWR) to have equipment from sensor output to final actuation device, that is diverse from the reactor trip system, to automatically initiate the auxiliary feedwater system and to initiate a turbine trip under conditions indicative of an ATWS.
In a letter from L. D.
Butterfield to.C. O. Thomas dated July 25, 1985 (OG-156), the Westinghouse Owner's Group (WOG) submitted Topical Report WCAP-10858, "AMSAC Generic Design Package", which describes three conceptual designs that meet this requirement at Westinghouse -
designed PWR's.
Union Electric is a member of the WOG and participated in the development of the Topical Report.
WCAP-10858 presents a conceptual design for an ATWS Mitigating System Actuation Circuitry (AMSAC). that would, upon detection of an ATWS event, actuate a turbine trip and initiate auxiliary feedwater flow.
Three methods available for detection of the ATWS event are:
1)
Low steam generator water level, 2)
Low. main feedwater flow, 8510230067 851014 _
7 PDR ADOCK 05000483 gk9 l
P PDR Mailing Address RO Box 149, St. Louis MO 63166 gQ, l
. 3)
Main feedwater pump trip or main feedwater valve closure.
Union Electric has not made a determination as to which parameters would be used as input to AMSAC and final selection depends, in part, on the design being approved as described in WCAP-10858.
Union Electric will implement AMSAC for Callaway at our third refueling outage.
This proposed schedule for implemen-tation is based in part upon the completion of the Staff's review of the WOG's AMSAC generic design package.
A period of approximately eighteen months will be necessary following receipt of the Safety Evaluation Report (SER) to allow for detailed design of the system (six months) and procurement of materials (12 months).
This 18-month period is contingent on the Staff not requiring a plant-specific design review prior to implementation at the Callaway Plant.
Union Electric anticipates that Callaway's second refueling outage will be in either the Spring or Fall of 1987.
Therefore, the lead time associated with detailed design and procurement of equipment, coupled with the incomplete sta ff review, does not allow for installation at Refuel 2, but necessitates that we commit to implement AMSAC at Refuel 3.
If NRC has not issued the SER on WCAP-10858 by December 31, 1985, we may need to re-evaluate this schedule.
Union Electric intends to submit a description of the final design and final implementation schedule within six months of receipt of the SER.
If you have any questions regarding this matter, please contact us.
Very truly yours,
)
/
4/N dl, Don-Schnell DS/lw
cc:
Gerald Charnoff, Esq.
'Shaw, Pittman, Potts & Trowbridge 1800 M.
Street-N.W.
D.C.
20036 Nicholas'A. Petrick Executive Director SNUPPS 5 Choke Cherry Road Rockville, Maryland 20850 G. C. Wright Division of Projects and Resident Programs, Chief, Section lA U.S. Nuclear Regulatory Commission Region III 799 Roosevelt Road Glen Ellyn, Illinois 60137 Bruce Little Callaway Resident Of fice U.S. Nuclear Regulatory Commission RRil Steedman. Missouri 65077 Tom Alexion Office of Nuclear Reactor Regulation U.S.
Nuclear Regulatory Commission Mail Stop P-316 7920 Norfolk Avenue Bethesda. MD 20014