ML20002C513
| ML20002C513 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 05/20/1976 |
| From: | Sewell R CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8101100397 | |
| Download: ML20002C513 (4) | |
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g ms DOCKET 50-155, LICENSE DPR N 4l BIG ROCK POINT PLANT
.i Your April 19, 1976 " Comments by the Director, Nuclear Reactor Regulation Relating to the Request for Exemption of the Big Rock Point Nuclear Power Plant From the Requirements of 10 CFR Section 50.h6" recommended that Consumers Power Company complete actions in five areas prior to returning the plant to service. The actions being taken in four of these five areas were described in our previous letters dated May 10 and May 11, 1976. The purpose of this letter is to provide a response regarding the fifth recommendation.
The fifth recommendation stated that prior to returning the plant to service, Consumers Power Company shall:
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Protect the controls, indication and annunciation circuitry associated with the ECCS, including core spray valves, as approved by the staff, against the consequences of flooding following a LOCA which affect the ability of the ECCS or plant operator to take corrective action during the course of a LOCA."
The problem with submerged electrical components was not recognized until after the Consumers Power Company-NRC staff March 19, 1976 meeting and our March 26, 1976 response to NRC staff questicas. This problem was that while the 125 volt d-c bus ves protected against loss due to flooding of a component because of the breaker tripping coordination, several ECCS alarm indication and control functions might be lost because the breakers feeding these components also feed other non-ECCS function equipment which might become submerged. The functions that might have been, jeopardized were:
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Station Service Annunciator Panel (includes ECCS indication and alarms).
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Nuclear Steam Supply Annunciator Panel.
3 Fire System Annunciator Panel.
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Containment isolation valve indication.
5 Core spray valves control and indication.
Items 1 through k above are being corrected by selective fusing of all individual circuits that could be jeopardized by LOCA effects (steam and flooding). These circuits will receive a signal or visual indicating type FNA Fusetron of 1/2 ampere size. This is a 13/32 x l-1/2 inch dual-element fiber tube, slow bearing fuse. This fuse has time current characteristics which, when compared to those of the circuit breakers utilized, insure that the fuses will clear before the breakers would trip. The fuses will be installed in the back of the control panels such that they are easily accessible for inspection. A blown fuse is readily detectable by observing the fuse pin. A blown fuse is quite evident because the fuse pin is in the extended position.
The ring core spray valves are located at elevation 586 feet inside the contain-ment and the nozzle core spray valves are located well above an elevation 600 feet. The level switches and pressure switches that actuate these valves are located at approximately elevation 590 feet. The water would rise to approxi-mate level 586 feet about two (2) hours after a LOCA assuming the most rapid rise conditions (feed-water flow continuous, broken ring spray and flow continuous, nozzle spray flow and flow from one containment spray).
The only operation of the core spray valves required after their initial opening
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in the early stages in a LOCA is the isolation of one core spray line prior to the start of the recirculation. Thus, we are procedurally requiring that within the first one and one half hours following a LOCA, the operator observes the core spray flow indication, appropriately isolates one core spray line and opens the
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breakers to all four core spray valves. This requirement will assure that the core spray valves are properly positioned for long-term cooling.
Simple guidance is being provided to the operator regarding which core spray system to isolate based on flow data from the hydraulic evaluation performed in conjunction with the hydraulic adequacy study. This data shows that a broken ring spray line is easily recognizable because flows are well in excess of those for nn intact ring spray or intact nozzle spray line. Thus, the procedures are being established instructing the operator to preferentially isolate the nozzle spray system unless the ring spray flows are either excessive or there is zero flow in the ring spray system and flow cannot be established in the ring spray system.
These procedural and equipment modifications will be completed prior to the start of significant power operation (generator synchronization).
Consumers Power Company and NRC staff representatives have also discurmed stan-dard Technical Specifications requirements for verifying that the battery capac-3 ity is adequate, battery discharge testing and capacity testing of the batte.ry charger. Although we have strongly objected to these types of testing in the past as we believe they are not necessary and that other methods of testing are f
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adequate, we hate agreed to develop the necessary procedures such that this testing :an be performed commencing prior to start-up from the next refueling outage. These procedures will include consideration of IEEE 450 consistent with the physical installation in the plant. We note that a discharge test was performed on the station battery in early 1975 and the UPS power supplies will be tested during the preoperational testing of the RDS which is currently
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N' %Y0 Wut Ral h B. Sewell Nuclear Licensing Administrator CC: JGiCeppler, USNRC A
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