ML20085F953

AO AO-7-74:on 740506,low Steam Generator Pressure Trip Setpoint Found to Be Less than Tech Spec Limit While Reviewing Monthly Tech Spec Surveillance Procedure MI-2. Caused by 15-volt Dc Power Supply & Dc Power Failure

ML20085F953
Person / Time
Site:	Palisades
Issue date:	05/16/1974
From:	Sewell R CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:	Oleary J US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20085F956	List: ML20085F953 ML20085F964
References
AO-7-74, NUDOCS 8308230676
Download: ML20085F953 (2)

Text

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gkgli)y General Offices: 212 West Michigan Avenue. Jackson. Michegan 49201. Area Code S17 788-0550 May 16, 1974

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\;s o Mr. John F. O' Leary, Director

\'//~ ,Of, I b6,N's Re: Docket 50-255 Directorate of Licensing License DPR-20 US Atomic Energy Commission Palisades Plant Washington, DC 20545 A0-7-74

Dear Mr. O' Leary:

Abnormal Occurrence Report A0-7 *(4 is attached. It is described as a power supply failure to the reactor protective sys-tem trip unit.

Yours very truly, Ralph B. Sewell (Signed)

RBS/ds Ralph B. Sewell Nuclear Licensing Administrator CC: JGKeppler, USAEC f

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O O l ABNORMAL OCCURRENCE REPORT Palisades Plant

1. Report Number: 74-7, Docket 50-255 2a. Date: May 16, 1974 2b. Occurrence Date: May 6, 1974

3. Facility: Palisades Plant i h. Identification of Occurrence: RPS Trip Unit Power Supply Failure 5 Conditions Prior to Occurrence: Refueling Shutdown 1

6. Description of Occurrence: While reviewing monthly Technical Specifi-cations surveillance procedure MI-2, it was found that the low steam

! generator pressure trip set point was less than the Technical Specifi-cations limit of 500 psi as specified in Table 2.3.1, Item 6. The limit was exceeded by 6.2 psia (0.025 MV).

7 Designation of Apparent Cause of the Occurrence: The 15 V d-c power supply 1hich provides trip unit isolation and d-c power failed causin- the trip point to be lower than the previously set trip point.

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8. Analysis of Occurrence: This type equipment failure is normal and

expected due to nonpermanent nature of filter capacitors. The system J

was designed (2 of 4 logic) to allow for these type failures and is monitored on a frequent interval to detect such failures. Only one of the four channels was affected by this failure.

9 Corrective Action: Replaced the power supply with a spare module and j readjusted the trip unit to proper set point.

10. Failure Data: This is the fourth failure of the forty-four 15 V power supplies in service at the Palisades Plant. Failures occurred on 1-19-70, 7-16-70, 2-27-72 and 5-6-74. The first two failures were returned to Windsor at Combustion Engineering request. No failure analysis was given. The third and fourth failures will be analyzed on site when time permits. Symptoms on the last two failures were dis-similar thus leading to the .lonclusion that the failures are not of a generic nature.

Manufacturers Identification: Dynage 700-262, Serial Number 6960

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