ML20056B682
| ML20056B682 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 12/21/1971 |
| From: | Mayer L NORTHERN STATES POWER CO. |
| To: | Morris P US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| NUDOCS 9102080344 | |
| Download: ML20056B682 (2) | |
Text
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'1 COMPANY 1.'
NORTHERN STATES POWER M I N N E A PO W S. MlN N E S OTA 9 5 4 01 December 21, 1971
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Dr. Peter A Morris, Director w
Division of Reactor Licensing T
United States Atomic Energy Commission g
-e Washington, D C 20545 v),.
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Dear Dr. Morris:
N MONTICELLO NUCLEAR GENFRATING PLANT Docket No. 50263 License No. DPR-22 Failure of ECCS Valve Opening Pemissive Switch Plant A condition has occurred recently at the Monticello Nuclear Generating 6 C 1 of the which we interpret to be reportable in accordance with Section 6...
Technical Specifications.
of this event.
i Summary of Occurrence _
t while perfoming a regularly scheduled surveillance tes,
itch #1, the trip setting of ECCS Valve Opening permissive switch PS 2-3-52B, sw On November 24, 1971, f 2 450 psig.
was found to be at 407.5 psig, 42.5 psi below the required setting o i
An investigat!on revealed that the instrument lacked a setpoint " locking" d The locking de/ ice a modification recommended by the instrument manufacturer.
60 peig.
was immediately installed, ano the instrument calibrate
" locking" device.
h Surveillance testing will be performed for all modified switches at twice t e forming normal frequency until we gain confidence that the instrumen l cement, erating policy used to evaluate instrument performance following rep aThis policy properly.
setpoint change, or other problems detected during testing d
d A Significant Operating Event report has been writtnn for this occurrence for review during j
will bt made available to the Region III Compliance Inspector m
his next visit.
4 Yours very truly, A
[f DEC 2% b -3
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L 0 Mayer Director of Nuclear Support Services g
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13 M-G It has been an established Practice to Operate the No.
set weekly to demonstrate its availability to the essential
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of this type of inci j
systems.
To prevent r rrene at which time an appropriate strainer in question wi
' dent p eti ter a f r the traine will be determined based on the results of that inspection.
g
~f view l'
This incident is not significant from a safety pois 1 had been in the cold, refueling ec.-
guration
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s ince Unit No.
at the time and the station batteries were capable or supplying for eight hours, which would have provided all essential loads more than ample time to effect the corrective measures outlined previously in the event off-site power had not been available.
Our Nuclear Facilities Safety Committee has reviewed the circumstances related to this incident and concurs in the remedial measures described herein.
Very truly yours, n
W 4
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