ML19350A568
| ML19350A568 | |
| Person / Time | |
|---|---|
| Site: | Maine Yankee |
| Issue date: | 03/09/1981 |
| From: | Groce R Maine Yankee |
| To: | Clark R Office of Nuclear Reactor Regulation |
| References | |
| 2.C.2.1, FMY-81-34, IEB-80-06, IEB-80-6, NUDOCS 8103160505 | |
| Download: ML19350A568 (4) | |
Text
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. MlM jATOMICF0WER COMPACH *
,e,,wonces,enno,o ENGINEERING OFFICE FRAMINGH AM, M# J ACHUSETTS o17o1 617 872 810o h
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w,g-2.C.2.1 FMY 81-34
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d March 9, 1981 A
h6 4,4 Eg United States Nuclear Regulatory Commission 87 Wa,hington DC 20555 A c0 N
Q Attention:
Office of Nuclear Reactor Regulation D
N U
Division of Licensing Mr. Robert A. Clark, Chief Operating Reactors, Branch No. 3
References:
(a) License No. DPR-36 (Docket No. 50-309)
(b) MYAPC letter to USNRC, WMY 80-94, dated June 13, 1980 (c) MYAPC letter to USNRC, WMY 80-117, dated July 29, 1980
Subject:
Engineered Safety Feature (ESF) Reset Controls
Dear Sir:
Maine Yankee recently held discussions with members of your staff and EC&G personnel regarding our response, References (b) and (c) to I6E Bulletin 80-06.
As a result of these discussions it was apparent that your consultant required further detail to review our submittal. The purpose of this letter is to provide this clarification.
A change is being engineered to modify the control circuitry for the valves listed in Reference (b) and (c).
This modification will be accomplished by installing auxiliary relays.
These relayF have a set of Contacts in series or parallel, as necessary, in their associat-d valve actuation circuit, that serve to " seal in" the SIAS or RAS signal which prevent the valve from repositioning when the ESF signals are reset.
The following 4 valves will not b e an auxiliary relay, but will be modified to function in the manner discussed above:
HCV-204T - Charging pump suction from RWST HCV-204U - Charging pump suction from RWST LCV-204V - VCT to charging PPS LCV-204S - VCT to charging PPS 8103160505-
United States Nuclear Regulatory Concission March 9, 1951 ATTN: Office of Nuclear Reactor Regulation Page 2
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Each of these 4 valves has two SIAS lockout relay contacts in their valve control circuitry, ene contact for opening, and one contact for closure (see Figure 1).
Upon an SIAS initiation, these contacts change state and force the valves to their safety position. Once the SIAS signal has been reset, these contacts return to their original positions which return the valves to their pre-actuation position. A =odification will re=ove the closing contacts of valves HC7-204 T&U and the opening contacts of LCV 204 S&U. The end result is that a SIAS will position these 4 valves in their safety positions, but once the SIAS has been reset, they will re=ain in their safety position until the operator operates their individual valve control switch.
The decision to modify HCV 204 S&V was =ade after a subsequent review of the valve actuation logic showed that an error was =ade in Reference (b), since these valves presently return to normal following reset of the SIAS lockout relays.
Following the i=ple=entation of these =odifications during the Maine Yankee 1961 Refueling Outage, the following actions will be required to reposition a valve fro = its " safety" position:
(a) Reset the ESF actuation signal, and (b) operate another switch (either the present valves' hand switch, er new reset switches).
Justification for exception to the requireeents of IE Sulletic E0-06 was provided in Reference (c) for Ite=s 18,19 and 20.
Although the justification provided was correct, further evaluation has deter =ined that other conditions could be postulated which would not fall within the bounds of the assu=ptions used in the justification.
For.this reasca, Maine Yankee has deter =ined that exception for Ite=s 18,19 and 20 would be inappropriate. The modifications described above will be-eade to the circuits of these valvss which will prevent then fro = auto =atically returning to a pre-CSAS posicion upon reset of the CSAS.
Circuit modifications for Ite= 1 (P-14A, B & S HPSI pu=ps) will not be made for the ' following reasons. These pu=ps are dual purpose pu=ps providing charging flow during nor=al operation and HPSI flow during accident conditions. At least one of these pu=ps will have 'been running prior to an SIAS, with a second pu=p in' standby which would auto-starr on either low
^ pressurizer level or low pressure in the charging header. Following an SIAS, both pu=ps will be operating in the HPSI = ode. Once the conditions which created the SIAS have been rectified, and the safety signal reset, both pu=ps will re=ain running unless a high pressurizer level or high charging header pressure exists. _ Should.either of these' two conditions exist, the pu=p originally in the standby mode (prior to the SIAS) will return to the standb7 mode. The other pump will re=ain running.
' Modifications to the circuits for Ite=s 4, 5, 9,16 and 17 are also considered inappropriate in view of the fact that the valves identified in
.these ite=s all provide charging or injection flow into the-reactor coolant system for pressurizer level control and seal water injection to the reactor-coolant-pumps. Upon reset of. the SIAS ' signal, these valves will return to their pre-SIAS position to rapidly restore pressurizer level control and re-establish seal water injection to the RCP's.
In addition to the
- desirability of rapidly restoring these functions to nor=al, the re-establishment of RCP seal water injection decreases the probability of tn m
United States Nuclear Reguistory Commission March 9, 1981 ATTN:
Office of Nuclear Reactor Regulation Page 3 l
degradation of the RCP seals which could compound the originating event and reduce the availability of the RCP's for immediate or future use. Again it should be noted that the alignment of any of these valves will provide flow of reactor coolent makeup water into the reactor coolant system.
We trust you find this information satisfactory: however, if you have any questions, please do not hesitate to contact us.
Very truly yours, MAINE YANKEE ATOMIC POWER COMPANY b
h Robert H. Groce Senior Engineer - Licensing RHG/mac A-
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