ML19351D263
| ML19351D263 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 10/03/1980 |
| From: | Mroczka E NORTHEAST UTILITIES |
| To: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| ETS-NR-50-245-5, NUDOCS 8010090373 | |
| Download: ML19351D263 (3) | |
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<t; October 3,1980 Docket Nos. 50-245 50-336 MP-1-1625 Mr. Boyce Grier
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Director, Region 1 Office of Inspection and Enforcement U.S. Nuclear Regulatory Comission 631 Park Avenue King of Prussia, PA 19406
Reference:
Facility Operating License Nos. DPR-21 and DPR-65 ETS-NR/50-245/50-336/80-1
Dear Mr. Grier:
Rursuant to the Millstone Environmental Technical Specifications, Section 3.2, Northeast Nuclear Energy Company hereby forwards the following report regarding anomalous radioactivity observed in oysters.
Very truly yours,
/ ?Co' dd E.
. Mroczka Station Superintendent Millstone Nuclear Power Station EJM/JWD:mw Attachment cc: Director, Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Comission Washington, DC 20555 Aco7 3
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8010090373 s
p Facility:
Millstone Nuclear Power Station Report Number:
ETS-NR/50-245/50-336/80-1 Report Date:
October 3, 1980 Occurrence Date:
August 12, 1980 DESCRIPTION OF OCCURRENCE:
The following levels of C0-58, Co-60, and Ag-110m activity were observed in the third quarter sample of oysters from within 500 feet of the discharge and these exceeded the control stations average activities by greater than a factur of ten.
Analysis Report Confirmation Results Date Date (pCi/g)
Co-58 Co-60 Ag-110m Control Stations -
Average of Giants Neck and Golden Spur 9/8 9/24 010.017 010.02 010.025 Within 500 feet of discharge 9/8 9/24 0.491 0.07 0.911 0.08 0.9810.10 PLANT OPERATING CONDITIONS PRIOR TO OCCURRENCE:'
Millstone Unit 1 - Operating at close to 100% power during July and August.
Millstone Unit 2 - Shutdown for refueling on. August 16, 1980.
CAUSE OF OCCURRENCE:
Natural oysters do not exist within 500 feet of the discharge. However, oyster trays are maintained in the discharge channel (quarry cut). Due to the location of these tray within the boundaries of the quarry and thus without any near-field dilution factors, and due to slight increases in plant liquid discharges the third quarter oyster sample showed plant relaced levels of C0-58, Co-60, Ag-110m, Cs-137 (0.03 pCi/gm), and Cs-134 (0.11 pCi/gm). anly the Co-58, Co-60, and Ag-110m were 10 times the control levels. A similar effect was observed and reported last year.
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CORRECTIVE ACTION:
The Appendix I Technical Specifications will result in spec 1fication of more realistic sampling locations in keeping with natural availability of shellfish and food pathways to man. These have been submitted to the NRC.
DOSE CONSEQUENCE:
Although natural oysters do not exist at or within the sample location, a dose calculation (Reg. Guide 1.109 methods) was performed, assuming an individual could have consumed shellfish having the Co-58, Co-60, Ag-110m, Cs-137, and Cs-134 concentrations as observed for the period of one quarter year. This results in a calculated dose to the critical organ, whicn in this case is the
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gastrointestinal tract - lower large intestine, of 0.13 millirem / quarter.
This is a small fraction (0.0043) of the natural background radiation exposure (30 millirem) to which this individual is normally exposed.
Thus the dose consequence of this event is insignificant. This reporting requirement is conservatively designed. Outside of the quarry, the plant dis-charges are rapidly diluted by the Long Island Sound to below detectable levels.
Thus the concentrations of radioactivity from the station are much less at locations outside of the quarry. The monitoring program at these locations verifies this.
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