ML20215E290
| ML20215E290 | |
| Person / Time | |
|---|---|
| Site: | Berkeley Research Reactor |
| Issue date: | 04/27/1972 |
| From: | Elliott D, Grossman L CALIFORNIA, UNIV. OF, BERKELEY, CA |
| To: | US ATOMIC ENERGY COMMISSION (AEC) |
| Shared Package | |
| ML20215E220 | List:
|
| References | |
| FOIA-86-811 2444, NUDOCS 8612220021 | |
| Download: ML20215E290 (3) | |
Text
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NI ERS15Y OF CALIF RNIA, BERKELEY
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COLLEGE OF ENCINEERING BERKELEY, CALIFORNIA 94720,,
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Dear Sir:
For your information I would like to report the failure of the period meter circuit of the Berkeley Research Reactor to operate properly on April 17 and April 20, 1972.
The sequence of events for the failure to operate properly on April 17, 1972 is as follows:
1.
At 2:55 P.M. on Monday, April 17, 1972,. the reactor was made critical for the first time that day and a class laboratory experiment (control rod calibration) in reactor operation was scheduled.
2.
The operator brought the reactor to 3 watts.
No malfunction of the period meter was noted by the operator at this time.
3.
The operator switched from the manual to the automatic mode of operation and linear scram resulted.
Presumably caused by a switching transient.
I 4.
As the operator prepared to withdraw rods and proceed to criticality again, he noticed the period meter was pegged at the -30 second period position.
5.
The class was temporarily dismissed and an electronics technician was brought in to diagnose,and correct the condition if possible.
The electronics technician and the Chief Reactor' 6.
Operator worked on the system for about one hour, at
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which time the system corrected itself.
No components j
were replaced in the system.
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g M4Y 11 ;972 The class was dismissed and the reactor secured for f
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the day.
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$1 The electronics technician did' determine that the period
,i meter was responding correctly to an input signal when it read
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-30 seconds.
Since the period scram circuit operates on the meter input signal the period scram circuit was not ' operational during the time period when the period meter was reading -30 secoads.
The~ technical specifications state that a scram must be initiated ti l at some period greater than 3 seconds, i
The failure to operate properly was reported by telephone to Mr. Ray Fish of the AEC-San Francisco Office on April 18, 1972.
As the circuit passed all normal operational checks the reactor was operated according to its normal schedule beginning on the morning of April 18.
Howe'e r on the af ternoon of April 20, 1972 it was noted that the console period meter was fluctuating radically.
The sequence of events for this failure to operate properly is as follows:
1.
The reactor period meter fluctuations were noted at 3:54 P.M.
on April 20, 1972.
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' :2.
The reactor was secured for the day and'all experiments were cancelled until the circuit could be permanently repaired.
3.
The circuit was examined by the Electronics Technician and Chief Reactor Operator and it was determined that the problem was in the operational amplifier circuit board.
While testing the operational amplifier, the circuit reverted to its failed condition of April 17 when the period meter was reading
-30 seconds.
l4.
On Friday, April 21, Gulf was contacted but they could give no clue as to the solution to the problem or to which components on the amplifier board were giving trouble.
Gulf did consent to supplying a replacement amplifier board and a replacement differentiator board for trial.
5.
The replacement boards arrived on Monday, April 24.
6.
The operational amplifier board was replaced and'following replacement the period meter circuit operated smoothly and fulfilled all normal operational tests.
7.
The circuit was calibrated by the Electronics Technician using the procedure outlined in the Gulf Maintenance manual.
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Following calibration the circuit was checked for proper operation by the Chief Reactor Operator with the Reactor Supervisor present.
This check included
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an induced period scram by withdrawing the Safety l
Rod with,the reactor critical at 10 watts.
I The second failure to operate properly was reported to Mr. Ray Fish of the AEC-San Francisco Office on April 25, 1972.
The normal reactor -operating schedule.has been followed since 12:00 noon of April 24, 1972.
Very truly yours,
//
p/r ///, (2 mum Lawrence M. Grossman Reactor Administrator p>./
Donald Elliott Reactor Supervisor LMG:DE: irs cc:
Mr. Ray Fish AEC 2111 Bancroft Way Berkeley, California e
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