ML17195A905
| ML17195A905 | |
| Person / Time | |
|---|---|
| Site: | Dresden, Quad Cities, 05000000 |
| Issue date: | 08/01/1985 |
| From: | Vassallo D Office of Nuclear Reactor Regulation |
| To: | Farrar D COMMONWEALTH EDISON CO. |
| References | |
| NUDOCS 8508080653 | |
| Download: ML17195A905 (3) | |
Text
Docket Nos. 50-237/249/254/265 Mr. Dennis L. Farrar Director of Nuclear Licensing Commonwealth Edison Company Post Office Box 767 Chicago, Illinois 60690
Dear Mr. Farrar:
August l, 1985
SUBJECT:
DRYWELL TEMPERATURE PROFILES Re:
Dresden Units 2 and 3 and Quad Cities Units 1 and 2 By our letter of April 11, 1985 related to drywell temperature equipment qualification profiles, we restated our position regarding credit taken for manual initiation of the drywell core. spray system within 10 minutes after onset of an accident, and clearly stated the basis for our position.
We sent you a drywell temperature profile curve based on a 30-minute interval before initiation of drywell spray, using analyses submitted for your Dresden and Quad Cities facilities as modified by the staff using the CONTEMPT code for the revised drywell spray initiation time.
We requested that you demonstrate that you ~an meet the conditions required for the assumed 30-minut~ period before initiation of drywell spray.
By your letter of May 23, 1985, you stated again your argument to justify a 10-minute interval rather than the more cqnservative 30-minute interval.
You stated that:
(1) the assumption of drywell spray initiation within 10 minutes is justified for licensing analys~s tn BWR plants; (2) the low pressure coolant injection (LPCI) mode of residual heat removal (RHR) is not needed in a postulated loss-of-coolant accident (LOCA) during the time when drywell sprays are needed;
- (3) the switchover from LPCI to drywell spray is a simple action which the*
operator is trained to perform; and (4) the 10-minute period for operator action is a conservative assumption and has been accepted as standard in the nuclear industry.
We have consid~red your response and find that the 10-minute perio~ is not acceptable for the reasons stated in our previous letter. The staff believes that it is not conservative to assume that the need for the low pressure coolant injection (LPCI) mode is satisfied and the switchover to asosoao6s3 asoao1
- t PDR
- ADOCK 05000237
- 1.
.. p. '.
. PDR I
1--..-'
--~~
\\ :~~./.:.:
. -~
- -.Mr~ Denn~is L.. Farrar
- 2 -
......... -~ ~
~
f b
- the ~rywell."spray cooling *mode can be commenced in.less t~an 30 minutes.
- Transfer* of the system from* the LPCI ;mode to the drywel 1. spray *mode
- requires~the control room operators tQ make decisiohs and take certain
. ma.nua1 actions.
With clearly defined procedures for initiating drywell
.$pray ~.ool;,ing, and a clear demon*stration that alignment to the reactor vesseJ in the LPCI mode can be terminated sufficiently early after ohset of any a_ccident., credit can be given for drywell spray initiation at approximately.JO minutes following onset*of-the acc.ident.
Your letter of May 23, 198.5 states that you would'.have to replace the BISCO loss-of-coolant accident (LOCA~ seals currently installed on a Target Rock-AVCO relief *valve and on one NAMCO limit switch for Quad Cities Unit. 1 and Dresden Unit 2 in order to.accommodate the use of drywell temperature curves assuming a 30'."minute period for drywell spray initiation.
As stated in our letter of January 11, 1985*re1ated to environmental qualificatfon of electrical equipment important to safety, should the results of our review of the tempera.ture profiles* used as the enveloping con.ditions for equipment
'qual ifi ca ti on identify a condition significantly different from that used for your equipment qualification, you would need to.asses~ the impact of that differing condition on your program.
- Our ~eview has identified an enveloping condition that differs significantlf from that which you assumed in qualifying your equipment - namely, the time required for drywell spray initiation.
In your assessmen~ of the impact as contained in your May 23, 1985 letteri you stated that you would need to re~lace the BISCO LOCA seals as described in your letter in order:to come within the acceptable 30-minute
- envelope. Accordingly, within 30 days of receipt of this lettei, you should provide us with your plans.and a schedule for any changes needed to come within the 30-minute*envelope ~s discussed above~
cc:
See next page DISTRIBUTION
~Docket Fi.l es**
NRC PDR....
Local PDR ORB#2 Reading HThompson Sinc.erely,.
- original signed by/
Domenic *s. Vassallo_, Chief Operatin_g Reactors Branch #2 Division of Licensing ELJordan BGrimes ACRS (IO)
Gray File JKudrick RLa~range, JPartlow OELD
- RGi l be rt SNorris JZwol inski RBevan
- Please see previous concurrence page.
DL :Q~~~?./,\\~ DL :ORB#2 OSI :CSB*
SN~fi'S":aj~
RBevan*
JKudrick*.
01 /03/~~
. o~ /24/85 _/ 01 /25/85 DL:OR(/!:(
DL:~.
JZwolinski DVassallo (J0/\\ /85
.,., / /85
- DE:EQB RLaqrange*
07/26/85 DL:ORB#5 RGilbert*
. 07 /25/85
\\-,.
'\\
1,,.'
r.
.\\;
(*
Mr. Dennis L. Farrar Commonwealth Edison Company cc:
Mr. B. C. O'Brien President Iowa-Illinois Gas and Electric Company 206 East Second Avenue Davenport, Iowa 52801 Robert G. Fitzgibbons, Jr.
Isham, Lincoln & Beale Three First National Plaza Suite 5200 Chicago, Illinois 60602 Mr. Nick Kalivianakis Plant Superintendent Quad Cities Nuclear Power Station 22710 - 206th Avenue - North Cordova, Illinois 61242 I
Resident Inspector U. S. Nuclear Regulatory'Commission 22712 206th Avenue North Cordova, Illinois 61242 Chairman Rock Island County Board of Supervisors Rock Island County Court House Rock Island, Illinois 61201 The Honorable Tom Corcoran United States House of Representatives Washington, D. C.
20515 Mr. Gary N. Wright Nuclear Facility Safety Illinois Department of Nuclear Safety 1035 Outer Park Drive, 5th Floor Springfield, Illinois 62704 Quad Cities Nuclear Power Station James G. Keppler Regional Administrator Region III Office U. S. Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, Illinois 60137