ML19317F922
| ML19317F922 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 12/13/1976 |
| From: | Mattimoe J SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| To: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| Shared Package | |
| ML19317F923 | List: |
| References | |
| NUDOCS 8002210640 | |
| Download: ML19317F922 (2) | |
Text
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(Q SMUD
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SACRAMENTO MUNICIPAL UTILITY DISTRICT C 1708 59th Street, Box 15E30. Sacramento, California 95813;(916) 452 3211 ggg December 13, 1976 s
Mr. R. H. Engelken Y
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Director of Regulatory Operations g
r2 NRC Operations Office, Region V E / ' t3 1990 N. California Boulevard ky-c.e.try -.Qh~d Waluut Creek Plaza, Suite 202 Walnut Creek, California 94596 p,,e Re: Operating License DPR-54 Qlll?,\\
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c Docket No. 50-312 Unusual Event 76-1
Dear Mr. Engelken:
j In accordance with Technical Specifications for Rancho Seco Nuclear Generating Station, Appendix B, Section 5.6.2.c, the Sacramento
, l-Municipal Utility Distirct is hereby reporting the following Unusual Event as UE 76-1.
J On May 5, 1976, the daily grab sample of plant effluent taken at a
0850 revealed a chlorine concentration of 0.3 mg/1, which exceeded the n.-
Technical Specifications, Appendix B, Section 2.2 limit of 0.2 mg/1.
The Shift Supervisor was immediately informed, who initiated a check of the chlorine levels in the circulating water basins and the sewer plant effluent to isolate the source. The check showed high levels coming from the sewer plant at which time the sewer hypochlorite pump
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vas secured. Plant effluent samples were taken at 1055, 1140 and 1200
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with chlorine concentrations of 0.26 mg/1, 0.2 mg/l and 0.12 mg/l respectively. These samples verified that the source of excessive chlorine had been located and that action had been taken to bring releases within specifications. A sample at Clay Creek near State Highway 104 taken at 1248 showed chlorine levels of less than 0.02 mg/l and a site boundary measurement of plant effluent taken at 1300 showed the concentration to be less than 0.02 mg/1.
Investigation of the sewage sump for the cause of the chlorine led to aiscovery of a loose coupling on the sewage pump motor. The set screw had backed out, allowing the motor to run continuously on high sump level which was not being reduced. The sewage hypochlorite pump operates when the sewage sump pump motor operates, which resulted in continuous chlorine injection causing the excessive concentrations.
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8002 210 ST O AN: ELECTRIC SY$ TEM SERVING MORE THAN 600.000 IN THE HEART OF CALIFORNIA
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k Mr. R. H. Engelken Decew' 13, 1977 The NRC Region V Operations Office was notified of the occurrence and SMUD was requested to hold reporting of the event pending clarification of the chlorine release limits.
It was necessary to deterr.iae whether the d
limit was a 24-hour average value or an instantaneous measurement limit
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and also whether it applied at the discharge. canal or at the site boundary.
On December 8, 1976, Region V informed SMUD that the limits are instantaneous at the site boundary and that the past events violatin3 these criteria were to be reported.
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The sewage sump pump, manufactured by Crane /Deming, was repaired
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to assure the motor would not uncouple in the future. The pump failure occurred during the period from 1510 on May 4 when the plant effluent sample showed 0.10 mg/l and 0850 on May 5 when the grab sample showed the excessive j level. The slightly elevated levels of chlorine released during this period c) did not produce any harmful offsite consequences.
There was no plant transient associated with the event.
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Respectfully submitted, i
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J. J. Mattimoe Assistant Ceneral Manager and Chief Engineer I#
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