ML19320C030
| ML19320C030 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 07/10/1980 |
| From: | Withrow G CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| IEB-80-17, NUDOCS 8007150664 | |
| Download: ML19320C030 (2) | |
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U July 10, 1980 Mr James G Keppler Office of Inspection and Enforce =ent Region III US Nuclear Regulatory Cc==ission 799 Roosevelt Road Glen Ellyn, IL 60137 DOCKET 50-155 - LICENSE DPR BIG ROCK POINT PLANT - RESPONSE TO IE BULLETIN NO 80 FAILURE OF 76 0F 185 CCNTROL RODS TO FULLY INSERT DURING A SCRAM AT A 3'a'R II Eulletin No 80-17, dated July 3, 1980 required surveillance tests to verify that no significant amount of water exists in the Scram Discharge Volume (SEV) and associated piping and that the SDV vent valves are operable and vent syste=
is free of obstruction. These surveillances were to be completed within 3 days from the da'.e of the bulletin.
The SDV sysi;em at Big Rock Point is significantly different from that at Browns Ferry Unit No 3 due tc the number of centrol rod drives and the design for handl-ing discharge water from the scram valves. The control rod drive system scram discharge piping consists of two scra: 6tp headers, each receiving the discharge from 16 scram outlet valves. These two scram du=p headers are connected together through a loop seal to tr.e scram dump tank (175 gal). The purpose of the loop seal is to maintain the scram dump headers full of water (h3 gal) to the scram outlet valves to prevent air leakage into the drives which could result in degra-dation of drive operation. The scram du=p tank (SDT) discharges through a normally open drain valve and associated normally open vent valve to the enclosure clean sump. Du=p tank instrumentation consists of level switches initiating a "hi-level" alarm at 10" below centerline (~ T gal) and " reactor scram" at 5/16" below center-line (~ Sh gal). The scram point selected is prior to a level which would prevent high speed insertion due to inadequate SDT volume.
(Ref: FHSR T.5.12) This trip prevents reactor operation vithout adequate SDT volu=e available for the scram function.
On July h, 1980, the surveillance test required by ite= 1 of IE Bulletin No 80-17 was performed to verify the cperability of the SDT system. All the requested 00/
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' bulletin actions vere ce=pleted and results found acceptable. The following steps
- were taken to ' verify operability:
1.
Initially SDT header drains downstrean of the SDT drain isolation valve were opened with no drainage evident. This verified that the SDT was empty and that leakage past the scram cutlet. valves during the present operations cycle, if any, drained properly without accumulation.
2.
The SDT was then filled above the alarm level by isolating the SDT drain and vent lines and initiating a one drive scram. This step also verified the operation of the "hi-level" alarm.
3 The SDT vent and drain isolation valves were opened. Total draining of the accu =ulated coolant (ael5 gal) in the SDT to the enclosure clean su=p took 15.3 seconds. This verifle; that both vent and drain valves functioned properly and discharge piping to the clean sunp was free to obstructions.
Gregory C Withrow (Signed)
Gregory C Withrev Senior Licensing Engineer CC Director, Office of Nuclear Reactor Regulation Director, Office of Inspection and Enforcement NRC Resident Inspactor - Big Rock Point 4
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