ML20038B533
| ML20038B533 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 12/02/1981 |
| From: | Nichols T SOUTH CAROLINA ELECTRIC & GAS CO. |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| GL-81-21, NUDOCS 8112080377 | |
| Download: ML20038B533 (2) | |
Text
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SOUTH CAROLINA ELECTRIC a GAS COMPANY POS1 OFFICE BOA 764 CotuMe A, south CAROLIN A 29218 4
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T. C. NICHOLs, J R.
Dec eber 2, 1981 Q
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Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation E,
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c U. S. Nuclear Regulatory Cminission edy,g'
- Washington, D. C.
20555
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Subject:
Virgil C. Sumer Nuclear Statiortb TI,M,b' '
Docket No. 50/395 NRC Generic Letter 81-21
" Natural Circulation Cooldown"
Dear Mr. Denton:
South Carolina Electric and Gas OJmpany (SCE&G), acting for 3
itself ard as agent for South Carolina Public Service Authority, hereby subnits the following in response to NRC Generic Letter 81-21,
" Natural Circulation Cooldown".
W e subject document requested:
1.
A dmonstration (e.g.
analysis and/or test) that controlled natural circulation cooldown frm operating conditions to cold shutdown conditions, conducted in accordance with your procedure, should not result in reactor vessel voiding.
Response: 'Ihe Westinghouse Owners Group subnitted to the NRC in July 1981 in letter OG-62 an analysis for Westinghouse plants showing their capability to cooldown by natural circulation to cold shutdown conditions without void formation in the upper head area. mis information vas subsequently provided in September 1981 to SCE&G as Emergency Response Guideline ES-0.2.
2.
Verification that supplies of condensate-grade auxiliary feedwater are sufficient to support your cooldown rmthod.
Response: As discussed in ESAR section 10.4.9, the Virgil C.
Sumer Nuclear Station condensate storage tank, frm which the energency feedwater pumps take suction, contains a minimum condensate-grade feedwater volume of 150,000 gallons. h is amount of water ensures the plant can hold at hotstandbyfortwohoursandthencoolgownthereactor coolant systs at an average rate of 50 F per hour to the conditions where the residual heat rm oval systs can operate. The cooldown method discussed in 1 above provides cooldown rates which are consistent with those used for the
- design basis of the annunt of water in the condensate storage tank. Berefore, an adequate annunt of water is available.
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Mr. Harold R. Denton December 2,1981 Page 2 3.
A description of your training gogram and the pcovisions of your procedures (e.g. limited cooldown rate, response to rapid change in gessurizer level) that deal with prevention or mitigation of reactor vessel voiding.
Response: 'Ihe Virgil C. Sumer Nuclear Station Training Departmant has addressed the St. Lucie event in their Pre-license Review Series and in operator simulator training. '1hese training sessions were designed to enable operators to avoid, recognize, and goperly react to reactor vessel voiding during natural circulation cooldown.
Discussion of this event will also be included in future requalification training programs.
Procedures are presently being revised to reflect the cooldown rate and sub-cooling temperature limitations specified in the WOG guidelines.
Should further information be needed, please contact us.
Very truly yours,
~ _ _
T. C. Nichol, Jr.
JWP:'ICN:lkb cc:
V. C. Sumer T. C. Nichols, Jr.
G. H. Fischer H. N. Cyrus H. T. Babb D. A. Nauman M. B. Whitaker, Jr.
W. A. Williams, Jr.
O. S. Bradham R. B. Clary M. N. Browne A. R. Koon G. J. Braddick J. L. Skolds J. B. Knotts, Jr.
B. A. Bursey J. C. Ruoff J. B. (bokinham NPCF File w
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