ML20041C510
| ML20041C510 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 02/25/1982 |
| From: | Bordine T CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | Crutchfield D Office of Nuclear Reactor Regulation |
| References | |
| GL-81-12, NUDOCS 8203020127 | |
| Download: ML20041C510 (3) | |
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CODSum8FS Power Company 4
General Offices: 1946 West Parnell Road, Jackson, Mt 49201 e (517) 788 0550 i
e February 25, 1982 b
HECGVED 1
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MAR 011982> @
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uunaeran m en IWumi mNam a Dennis M Crutchfield, Chief g
irc Operating Reactors Branch No 5
, *, } D Nuclear Reactor Regulation US Nuclear Regulatory Commission Washington, DC 20555 DOCKET 50-155 - LICENSE DPR BIG ROCK POINT PLANT - PROPOSAL FOR AN ALTERNATIVE METHOD OF PROTECTING EMERGENCY CONDENSER INLET VALVES FROM HOT SHORTS NRC letter dated November 24, 1980 transmitted a revised Section 50.48 and a new Appendix R to 10 CFR 50 regarding fire protection features of nuclear power plants. The new 10 CFR 50.48 defines specific actions to be taken by all licensees and invokes a number of specific design requirements as detailed in Appendix R.
For the Big Rock Point Plant, the portions of Appendix R which l
thereby became applicable are Sections III.6, Fire Protection of Safe Shutdown Capability; III.J, Emergency Lighting; and III.0, Oil Collection System for Reactor Coolant Pump. Consumers Power Company submittal dated March 19, 1981 provided brief descriptions and schedules for completion of those modifica-tions noted above.
In Consumers Power Company letter of May 19, 1981, we provided our responses to the detailed information requests of NRC Generic Letter 81-12, dated February 20, 1981. We stated that fire damage and consequential closing of the emergency condenser inlet valves will be prevented by removing operating power from the valves, after checking the valves open prior to reactor operation. Upon further review by the Big Rock Point Plant Review Committee, a decision was made to retract this commitment to remove operating power from the emergency condenser inlet valves.
The rationale behind this commitment retraction includes the fact that the power breakers for the emergency condenser inlet are located inside contain-ment.
It is possible that under some conditions these valves would have to be operated when containment is inaccessible. One such possibility would be an emergency condenser tube bundle rupture, which constitutes a small-break LOCA.
l Without the ability to isolate the tube bundle, the primary system would be l
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oc0282-0018a142 h
8203020127 820225 b\\
PDR ADOCK 05000155 F
D M Crutchfield, Chief 2
Big Rock Point Plant Hot Shorts-Emer Condenser Inlet Valves Februa ry 25, 1982 venting directly to the atmosphere. Containment would be uninhabitable due to the actuation of the reactor depressurization system.
An alternative method of protecting these valves from hot shorts is currently planned. This consists of removing wires number 6 and 7 from the multi-conductor cable (which runs from the control room through containment to the valve operator reversing starter within containment) and routing them from the control room to the starter in a separate cable for each valve operator. A different penetration assembly for each cable will be utilized; both of which are separated from the original penetration assembly. These two wires connect one end of the opening and closing contactor operating coils to the hot source of control power through the local, remote, and seal-in switches. The removal of these wires, particularly the wire from the closing contactor operating coil to the hot source, will eliminate a very remote possibility of fire damage causing a hot short and unwanted valve closing of one emergency condenser inlet valve and an even more remote possibility of the same fire damage causing both valves to close. Figure 1 attached displays the emergency condenser inlet valve schematic.
Consumers Power Company in response to our May 19, 1981 commitment to the NRC, Generic Letter 81-12, will therefore install the above alternative circuitry for the emergency condenser inlet valves in accordance with the schedule of 10 CFR 50.48(c)(3).
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Thomas C Bordine Staff Licensing Engineer CC Administrator, Region III, USNRC NRC Resident Inspector-Big Rock Point Attachment - Figure 1 oc0282-0018a142
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