ML20077E348
| ML20077E348 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 05/31/1991 |
| From: | Creel G BALTIMORE GAS & ELECTRIC CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| RTR-NUREG-0737, RTR-NUREG-737, TASK-2.E.4.2, TASK-TM NUDOCS 9106100039 | |
| Download: ML20077E348 (3) | |
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F3 ALTIMORE GAS AND ELECTRIC CHARLES CENTER
- P.O. BOX 1475
- BALTIMORE, MARYLAND 21203-1475 GroRoc C Cacto s er pac u r.o Nstt t am r m.t no, t.* 61 ) JSO 4e8$
hiay 31,1991 U. S. Nuclear Regulatory Commission Washington,DC 20555 NITENTION:
Document Control Desk
SUBJECT:
Calvert Cliffs Nuclear Power Plant Unit Nos.1 & 2: Docket Nos. 50-317 & 50-318 Clarification of Containment Vent Status
REFERENCES:
(a)
Letter from hir. A. E. Lundvall (BG&E) to hir. D. G. Eisenhut, (NRC) dated April 19,1982, Post Thil Requirements (b)
Letter from hir. A. E. Lundvall (BG&E) to hit. D. G. Eisenhut, (NRC) dated August 11,1981, Response to NUREG.0737 (c)
Ixtter from hit. D.11. Jaffe (NRC) to hir. 4. E Lundvall (BG&E),
dacd February 1,1982. Issuance si @ce..nent Nos. 65 and 47 Gentlemen:
While reviewing containment ventmg practices, we discovered several items which we felt should be brought to your attention. We have determined that an inaccurate statement was made in Reference (a). This document was cited by the NRC in its close out of Tht! Action item II.E.4.2.
AMitionally, we have determined that there is no documentation which describes a safetv analysis for ti currently used vent path. We have discontinued all activities not complying with the Thil Action Item requirements by ceasing venting through this path. These matters have been discuv,ed with your staff, and this letter is provided to communicate our plans for resolution of these issues.
Th11 Action item II.E.4.2 Reference (a) updated our status on several Thil Action items including II.E.4.2. In this letter, we state that our " containment purge and vent valves" shut on a radiation signal. This statement is not accurate. While our purge vahes close upon receipt of a high radiation signal and a Sl AS, there were no valves designated as " containment vent valves." The valves used for containment venting (containment sump isolation valves) close upon receipt of a SIAS, but not on a radiation signal.
Previous correspondence (Reference b) had indicated that only the Containment Purge Valves close upon receipt of a high radiation signal. Only Reference (a) was cited by the NRC in closing out this h [/
action item (Reference c).
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e Document Control Desk May 31,1991 Page 2 1
In 1982, we decided to modify the hydrogen purge line for use as our containment vent path. A containment radiation signal was installed on this line in 1985; however, due to difficultly with the detector,it never worked properly. The containment radiation signal to the hydrogen purge line was never declared operable as requir~i by our Technical SpeciGeations, and it was not irnplemented as a vent path. Work is underway now. provide a high radiation signal which will function during power operation. We are currently in ecmpliance with the intent of TM1 Action item because we have discontinued venting. Because a containment vent path is an operational necessity long-term, we believe this TMI Action item should be held as an open item until an acceptable pathway has been established. We expect this to be accomplished in the very near future.
Alternate Vent Path We have also researched the basis for the use of our alternate vent path. This path consists of using the normal containment sump and venting the containment atmosphere to the ECCS pump room.
This pathway is automatically isolated by redundant containment isolation valves upon receipt of SIAS. The procedure implementing this path has been in use since 1979, when it was approved as an alternate to our 48" purge valves. We can Gnd no written safety analysis which justifies the use of this path.
We have reviewed this path to determine if its use might have put us in an unsafe condition. It is of minimal safety signiGeance for two reasons. First, the radiological consequences have been evaluated for a LOCA while venting through a similar line and have shown that the associated offsite dose would be negligible, Second, although there is no containment radiation signal on the sump isolation valves, we have identiGed no plausible accident for which the radiation signal will actuate before SIAS.13ccause of the diversity and redundancy of the SIAS signal, we have concluded that the lack of a high radiation signal on the sump isolation valves is of minimal safety significance.
We discontinued venting through the sump upon dUcovery that written analyses could not be located. This path does not fully comply with the requirements of the TMI Action item.
Future Actions Currently, we have no vent path which is in full compliance with the TMI Action Plan requirements.
Our intention to resolve this issue is to install the modifications necessary to make the hydrogen purge line conform to the NRC approved conGguration. The hydrogen purge line requires several modiGeations to make it operable as a containment vent path. The high radiation signal must still be installed on the valves and an oriGce plate must be installed to limit the flow through the line while venting. Both of these modifications are proceeding as expeditiously as possible.
If during the current modifications an operational need to vent occurs, we wi!I take action in accordance with the Technical Specifications to shutdown the plant to Mode 5 to accomplish the venting.
Should an unforeseen obstacle prevent prompt installation of the modifications, we will evaluate the options available at that time, including requesting a waiver of the Technical SpeciGeation requirements.
.i Document Control Desk
- May 31,1991 Page 3 An investigation of tne circumstances involved in these issues is in progress.
Should you have any questions regarding this matter, we will be pleased to discuss them with you.
Very truly yours, i
.J M
for G. C. Creel Vice President - Nuclear Energy GCC/ PSF / psf / dim ec:
D. A. Brune, Esquire J. E. Silberg, Esquire R. A. Capra, NRC D. G. Mcdonald, Jr., NRC T. T. Martin, NRC L E. Nicholson, NRC R. I. Mclean, DNR J. II. Walter, PSC l
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