ML19317F925
| ML19317F925 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 12/14/1976 |
| From: | Mattimoe J SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| To: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| Shared Package | |
| ML19317F926 | List: |
| References | |
| NUDOCS 8002210642 | |
| Download: ML19317F925 (2) | |
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~,sSMUD SACRAMENTO MUNICIPAL UTILITY DISTRICT C 1708 59tn Street, Box 15830, Sacramento, California 95813:(916) 452 3211 V
December 14, 1976 T FILE (X)PE Mr.-R. H. Engelken y
Director of. Regulatory Operations NRC Operations Office,~ Region V 1990-N. California Boulevard
-Walnut _ Creek Plaza, Suite 202
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Walnut Creek, California 95846
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Re: Operating License DPR-54
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Docket No. 50-312 Unusual Event 76-2 f
Dear Mr. Engelken:
'9 In accordance with Technical Specifications for Rancho Seco Nuclear Generating Station, Appendix B, Section 5.6.2.C, the Sacramento Municipal Utility District is hereby reporting the
,J following Unusual Event as UE 76-2.
i Nj On May 12,1976, at 1045, the daily grab sample of plant effluent showed a chlorine concentration ef 0.8 mg/1.
This exceeds the Technical Specification, Appendix B, Section 2.2 limit of 0.2 mg/1.
The Shif t Supervisor was informed of the high levels, who directed that dilution flow be increased from 400 gpm to 4000 spm and that the
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sewer pump stroke be reduced to 20%. The sewer discharge chlorine concen,
tration was 27 mg/l at 1050, identifying it as the source of the high level at the effluent discharge point. At 1130 the site boundary concentratic,a was-found to' be 0.4 mg/1, with a sample of Clay Creek near State Highway 104 showing <0.02 mg/l at 1140.
Plant effluent levels dropped to 0.15 mg/l at 1145 and 0.1 mg/l at 1245 and the site boundary sample showed s.1 mg/l at 1255.
The hypochlorite tans, a 100 g.tllon PVC tank, manufactured by Milton Roy Company, had a crack at the' 50% level for several months prior to the incident. The location of the crack only permitted batch mixing of 50 gallons.in the tank. An Operator added the hypochlorite necessary
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for a 100 gallon (full tank) mixture when making a 50 gallon' batch,
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resulting in'overchlorination.
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Mr.-R. H.LEngelken.
- December 14, 1976 Immediate. corrective' action was initiated to insure that clear-
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directions on filling the hypochlorite tank were available to the Operators.
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~The' tank has now been replaced with a 1/4" steel tank-(lined) which will
- solve the mixing problems :and prevent future cracking.
- The-NRC Region V Operations Office was notified at the time of the Joccurrence and SMUD was -requested to hold reporting of the event pending clarification of the chlorine release limits..It was necessary to determine whether that(limit was a 24-hour ' average valve or an instantaneous measurement limit and also whether it applied at the discharge canal or at the site boundary.
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thesite-boundaryandthatpasteventsviolatingthese'p On December 8, 1976,_ Region.V informed 1SMUD that the limits are for instanta z
r's eous.neasurements at criteria were to be' reported.
The slightly elevated levels of chlorine released during this event Ldid not produce'any harmful consequences and there was no. plant transient
'a associated with this event'.
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Respectfully submitted, gf
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I/J. J. Mattimoe
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4 0 Assistant General Manager and Chief Engineer s
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