ML19309A396
| ML19309A396 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 10/09/1974 |
| From: | SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| To: | |
| Shared Package | |
| ML19309A393 | List: |
| References | |
| NUDOCS 8003270845 | |
| Download: ML19309A396 (3) | |
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,2 ABNORMAL OCCURRENCE REPORT DOCKET No. 50-312-74-5 Reporting Date:
October 9, 1974 Occurrence Date:
October 3, 1974 Time: 0703 Facil g :
Rancho Seco Nuc1 car Cencrating Station Unit No. 1 Clay Station, California Identification of Occurrence:
A reactor startup was conducted with the Borated Water Storage Tank capacity below the minimum established in the Technical Sp'ecifications, " Limiting Conditions for Operation".
Condition Prior to Occurrence:
The reactor was at hot shutdown subsequent to completing the initial Zero Power Physics Tests.
p bription of Occurrence:
iV Prior to the occurrence, the Spent Fuel Pool water icvel was low and the low icyc1 alarm was actuated. The filling procedure intended to take horated unter from the Borated Water Storage Tank (BUST) and pump to the Spent Fuel Pool via % Spent Fuel Coolant Dcmineralizer Pump.
Since the Spent Fuci Pool was several feet low and a minimv volume of 390,000 gallons is
' allo,ued in the BWST, the pool was to be raised by the excess volume above 390,000 gallons in the BWST. Once the minimum BUST 1cvel was reached, the pool filling was to be stopped. The BWST icvel would then be re-established by adding boron from the Concentrated Boric Acid Storage Tank and demincralized water from the Miscellaneous Water lloidup Tank and the-cycle would then be repeated. This operation was to start the morning of October 3.
The on-duty shift filled the Spent Fuel Pool to normal level with a singic operation which decreased the BUST le u l to 375,000 gallons. This operation was completed at 0455 on October 3, 1974.
The initial Zero Power Physics Testing Program had been completed and scheduled supervised startups were to be performed by unlicensed operators for training. A trainee reported to work at 0600.
Prior to startup, several administrative operating procedures must be completed to verify plant conditions. One of those pr'ocedur:s is B-1, " Plant Prestartup Checks".. Enclosure 5.1 of the procedure. requires the opet >or to check the BWST gallonage to be greater than 3.9 x 10 ' gal. The training operator checked the procedure against a previous 5
verification performed the day before. lie had understood.from the licensed operator.
f When the trainee f ft no plant conditions were changed during this time span.
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us, completed the check for startup #30, the Senior Licensed Operator who was aware of tha BWST 1cyc1 decrease earlier signed the procedure as being complete. The reactor wra brought critical by the trainec at 0703 with Group 5 at 91% withdrawn and. Group 6/7 cc 15%.
The Operations Supervisor entered the Control Room and noticed that the Spent Fuel Pool low level alarm was cleared. This indic'ated to him that a greater quantity of water than intended had been transferred from the BUST to the Spent Fuel Pool.
He immediately checked the BWST level. Comparing the level with ths volume curve (gallonage) he confirmed _.that the BWST was below the minimum 390,000 gallonn and requested the reactor to be shut down.
The reactor was tripped at 0720.
Corrective Action Taken or Which Should be Taken:
The reactor remained at hot shutdown.
Borated water was transferred from the Spent Fuel Pool back to the BUST at 1031 the same day.
The lavel was re-established above the 390,000 gallon specification and has not been 2
decreased.
1 Designation of Apparent Cause: Operator.
Analysis of Occurrence:
f' 'x The Shift Supervisor thought that the Technical Specification
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joum volume uns 350 000 gallons a d proceeded accordingly. I.ere was no transient n
t.uolved during this occurrence.
Equipment I.D.:
Not Applicable.
Action Rqquired to Prevent a Reoccurrence:
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- 1) The procedure states the minimum volume of the BKST to be >390,000 gallons.
However, the readout in the l
Control Room read the volume in units of feet and a conversion chart must be referenced. The procedure
.h has been changed to read out in units that are displayed in the Control Room, i.e.,
change 390,000 gallons equates to 41 ft. 8 inches. The B-1 procedure has been reviewed
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for similar inconsistencies and corrected.
- 2) The operating personnel have been instructed not to use previous data when verifying parameters which are readily l
available via existing instrumentation.
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- 3) The B-1 procedure has been revised to require reverification I
if the actual reactor startup is delayed four hours beyond completion of B-1.
&lureData:
Not Applicabic.
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