ML20215E260
| ML20215E260 | |
| Person / Time | |
|---|---|
| Site: | Berkeley Research Reactor |
| Issue date: | 08/10/1976 |
| From: | Lim T CALIFORNIA, UNIV. OF, BERKELEY, CA |
| To: | Crews J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| Shared Package | |
| ML20215E220 | List:
|
| References | |
| FOIA-86-811 NUDOCS 8612190057 | |
| Download: ML20215E260 (1) | |
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CALIFORNIA, BERKELEY 0
SEnrrr_n
- DAY 13
- IRVINE
- 1.0$ ANCELES
- RIVERSIDE rg 4,. -
- SAN DIECO
- SAN FRANCISCO i;
SANTA BARBARA
- SANTA CRUZ-3 COLLEGE OF ENCINEERINC
' s DEPARTMENT OF NUCLEAR ENCINEERINC BERKELEY, CALIFORNIA 94720 August 10, 1976 9
s Mr. J. L. Crews Chief of Reactor Operations b YO-and Nuclear Support Branch j
12 [973 p U.S. Nuclear Regulatory Commission 1
to Walnut Creek, California fu y
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Dear Mr. Crews:
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the second letter sent to Nuclear Regulatory CE mission, Washington, explaining the unusual occurre om-that occurred during reactor operations on th 6th of July 1976.
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Very truly yours, 1
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Tek Lim Reactor Supervisor TL: irs enc.
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CALIFORNIA. BERKELEY k-
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$ANTA BARBARA
- SAhTA CRUZ 333tEI2.EY
- DAY 15
- IRVINE
- LOS ANCELES
- RIVERSIDE
- SAN DIEGO
- SAN F1MNCISCO y f2?
C COLLEGE OF ENGINEERINC BERKELEY, CALITORh% 94720 DEPARTMENT OF NUCLEAR ENGINEERINC August 2, 1976 Docket No. 50-224 Director Division of Operating Reactors Office of Nuclear Reactor Regulations U.S. Nuclear Regulatory Commission Washington D.C.
20555
Dear Sir:
On July 9th, 1976, a letter was sent to your office reporting an unusual occurrence on the Berkeley Research Reactor linear power channel during a routine power calibra-tion.
It was reported then, that non-linearity occurred in the linear power channel output with respect to rise in pool temperature during the early part of measurements, especially near the 1 MW region.
It was also reported that because of this nonlinear occurrence, we might have operated exceeding our license of 1 MW thermal limit.
Since then, extensive measurements and testing have been made.
Results show that nonlinearity during power calibration occurred during the first 30 minutes of the measurements only.
The cause was deternined to be a thermal transient rather than an electronic or ion chamber malfunc-tion.
It was also established that after the first
- 30. minutes of measurements a steady-state condition was reached and that the linear channel responded quite linearly with respect to rise in temperature up to pool temperature of 30*C.
Attached is a graph of one of the measurements per-formed on the 15th of July at a power level of 900 kW as calibrat-ion setting was maintained at 6.44 x 10-garder current indicated on the linear recorder.
The 1inear re Amp /kW indicated on the~ recorder.
As one'can see from the graph, during the first 20 minutes of operation, a thermal transient occurred and the average rise in temperature was approximately 9*C/ hour -
900 kW indicated on the linear recorder.
Extrapolation of this number gave a power coefficient of 10*C/ hour - 1 MW indicated.
After the first 30 minutes, a steady state was reached and an average power coefficient of 6.6*C/ hour -
900 kW or 7.37*C/ hour - 1 MW indicated was recorded.
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- August 2, 1976 On the reported reactor operation on July 6, a similar calibration pattern was obtained.
It was reported that during the first 20 minutes of operation a temperature rise of 3.4*C was noticed; this corres-ponded to 10.2*C/ hour.
The reactor was then scrammed after.26 minutes of operation.
This number is approxi-mately.2% higher than the one obtained during the test on July -15.
Analysis and comparison of transient and steady state' data collected during the 3 weeks of testing concluded that, within 5% accuracy specified by General Atomic, during the 26 minute reactor operations on July 6, 1976, we did not exceed our licensed 1 MW the'rmal limit.
In order to stay on the conservative side of safety, the linear power, channel calibration current is now set to 6.35 x 10. Amp /kW indicated.
This setting will correspond to thermal power output of 986 kW as per 1 MW indicated on the linear recorder.
Very truly yours,
% G Pi Stanley G. Prussin Reactor Administrator
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