ML20002C631
| ML20002C631 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 01/29/1974 |
| From: | Sewell R CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | Oleary J US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| NUDOCS 8101100623 | |
| Download: ML20002C631 (3) | |
Text
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~r (egulatory Docket (
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January 29, 1974 D
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4 Docket 50-155 Mr. John F. O' Leary, Director Directorate. of Licensing 6%
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Big Rock Point US Atcznic Energy Comission 4
Washington, DC 20545 g9 A
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Dear Mr. O' Leary-
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Consumers Power Company's letter of December h,1973 provided additional inform 9 tion to the Regulatory Staf f to allow farther evaluation of the Technical Specifications e;overning testing of the Big Rock Point Liquid Poison System explosively actuated valves.
In that letter,*e de-scribed difficulties with a special test procedure that we were attempting to develop to periodically test the actuation circuitry. This letter is to inform you of the resolution of the difficulties with the special test procedure and to correct one error in the December 4, 1973 letter.
Our December h,1973 letter stated that a special test was per-formed on the actuation circuitry in November 1973, which involved replacing the primers with fuses. During the first attempts, the fuses did not all blow as expected. Subsequent attempts were successful. During December 1973, further testing was perfomed and the cause of the previously unex-pected results determined.
Testing was perfomed with various sizes of fuses in place of the explosive valve primers. The fuse sizes varied from 1/2 amp to 2 a=ps in 1/2-amp increments. The circuit was energized and the fuses opened, simulating primer firing as follows:
Fuse Size (Amn)
Anproximate Time To Open (Seconds) 1/2 Too fast to measure.
1 0.2 1-1/2 0.6 2
Circuit A - one fuse opened, others were glowing red.
Test halted aft.er 2.h seconds.
Circuit B - last fuse opened at 2.18 seconds.
Current was measured in Circuit A at 15 amps maximum.
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2 Mr. J hn F. O'L;ary Docket 50-155, License DPR-6 January 29, 1974 The recults of these tests were compatible with the capability of the installed circuitry. Measurements and analyses show the circuitry to be capable of supplying approximately 15 amps to the seven priners in parallel. The six remaining unopened 2-amp fuses in Circuit A probably would have opened if the circuit had remained energized longer.
Based on these test results, the Big Rock Point Plant Staff is implementing a test of the liquid poison system control circuits, utilizing 1-1/2-amp fuses in place of the primers. This test will be performed at each major refueling outage. Test actuation of the 1-1/2-amp fuses will ensure that adequate current will be provided to fire the explosive primers.
The specified maximum current required for firing a primer is 1 amp and tests have shown that the primers are detonated with the application of approxi-mately 1/2 amp. In addition, administrative controls will be incorporated such that the hand switch be held in the firing position for five seconds.
The actuation circuits do not seal-in and rapid switching could prevent valve firing.
Further aralysis of the poison system control circuit malfunction alarm stssed it to ' e functioning as intended. The control circuit failure alarm is provided t, indicate an open circuit condition that is assumed to occur during normal plant operation.
The poison system control circuit alarm was not intended to pro-vide mcuningful information if the control circuit is actuated and in this case is misleading.
If actuation is at',empted and all primers detonate, a malfunction alarm is received.
If actuat'on is attempted and none or some primers detonate, no malfunction alarm is received.
The December 4,1973 letter also contained a statement that was erroneous. The December 4 letter stated "... the valves that experience the highest temperatures will not be in service for periods exceeding one year." Section 5 2.3 requires that the two valves that experience the highest temperatures be removed from service for testing at least every two years.
Yours very truly, "w"
RBS/ map Ralph B. Sewell Nuclear Licensing Administrator CC: JGKeppler, USAEC
AEC DISTRIBUTION F02 PART 50 DOCKET MAT" RIAL (TEMPORARY FORM)
CONTROL NO:
882 1
FILE:
FRCM DATE OF DOC DATE REC'D LTR MD10 RPT OTHER Consum/rs Power Company JIckson, Michigan 49201 1-29-74 2-1-74 X
R. B. Sewell TO:
J. F. O' Leary, 1 signed SENT LOCAL PDR X
CLASS UNCLASS PROP INFO INPUT NO CYS REC'D DOCXET NO:
XXX 40 50-15'S
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DESCRIPTION:
ENCLOSURES:
Ltr re their 12-4-74 ler........ furnishing a resolution of the difficulties with the special test procedure and to correct one error,.....
DON 07 :
PLANT NAME: Big Rock FOR ACTION /INFORMATION 2-4-74 GC BUTLER (L)
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C. MILES P. COLLINS ROSS KNIGHTON TEETS (L)
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