ML20126E983
| ML20126E983 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 11/14/1972 |
| From: | NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | |
| Shared Package | |
| ML20024G193 | List: |
| References | |
| 50-263-72-06, 50-263-72-6, NUDOCS 9212300068 | |
| Download: ML20126E983 (1) | |
See also: IR 05000263/1972006
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differential pressure variations which resulted in a reactor scram.
Following a safety evaluation, the modification was approved by the
Operations Committee in June 1971, with the reconsnendation that
periodic response time checks be made to ensure against plugging
of the snubbers. Operational checks were performed following
installation by the application of a differential pressure to the
sensing lines, with switch response times observed to be less than
one second (to switch set point equivalent to 144 percent of the
full power differential pressure). At the request of the Safety
Audit Counnittee, a procedure for the measurement of response time
was also developed. Performance of this procedure in the workshop
with a spare differential pressure switch and associated snubbers
yielded a response with a time constant of 1.28 seconds as compared
to an allowed time constant of 2.5 seconds (corresponds to a trip
response time of 0.4 seconds, as assumed by the FSAR).
13.
Failure of Hain_ Steam Line j rain Valves to Close
A licensee reportM / discussed the failure of a main steam line ,
drain valve to close on July 28, 1972. Discussions with plant
staff personnel indicated the event to have been as described in
the subject report. As stated in the report, a followup inspec-
tion revealed 12 contactors to have loose screws. Licensee
personnel concluded that the screws had apparently not been
sufficiently tightened during initial manufacture. All loose
screws were tightened as necessary, which should prevent recurrence,
since lockwashers are provided.
14. MSIV Reset Switches
During a previous inspection 3.2,/ the licensee indicated an intention
to install a second MSIV reset switch during an outage in May 1972,
such that one switch would reset the inboard and one switch would
reset the outboard MSIV's. The inspector verified by observation
of the control panel that the intended installation had been completed.
15. _ Fuel Pool Siphoning
The potential for inadvertent siphoning of the fuel pool was discussed
with a plant staff representative during the inspection and a subse-
quent telephone conversation. Discussion with the licensee representa-
tive and review of a piping diagram of the fuel pool system indicated
11/ Letter, NSP to Directorate of Licensing, dated 8/28/72
12] RO Inspection Report No. 050-263/72-03
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