ML19351D287
| ML19351D287 | |
| 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 | |
| MP-1-1625, MP-2-4494, RO-ETS-NR-50-24, NUDOCS 8010090449 | |
| Download: ML19351D287 (3) | |
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L October 3,1980 i
Docket Nos. 50-245 j 50-336 MP-1-1625' Mr. Boyce Grier
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Director, Region 1 Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission 631 Park Avenue King of Prussia, PA 19406
Reference:
Facility Operating License Nos. DPR-21 and OPR-65 ETS-flR/50-245/50-336/80-1
Dear Mr. Grier:
Pursuant 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 yo n
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. Mroczka Station Superintendent Millstone Nuclear Power Station EJM/JWD:mw Attachment Director, Office of Nuclear Reactor Regulation cc:
U.S. Nuclear Regulatory Commission Washington, DC 20555 8010090Wf g
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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 cysters from within 500 feet of the discharge and these exceeded the control stations average activities by greater than a factor 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 0.49+ 0.07 0.91+ 0.08 0.98+0.10 PLANTOPERATINGCONDITIONSPRIORTOOCCURRENFEi Millstone Unit 1 - Operating at close to 100% power during July and August.
Millstone Unit 2 - Shutdown for refuelir.3 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 trays 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 related levels of C0-58, Co-60, Ag-110m, Cs-137 (0.03 pCi/gm), and Cs-134 (0.11 pCi/gm).
Only 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 specification of more realistic sampling locations in keeping with natural availability of shellfish and food pathways to man.
These have been submitted to the NRC.
i 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, which in this case is the 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, i
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