ML20030B338
| ML20030B338 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 07/02/1981 |
| From: | Mroczka E NORTHEAST UTILITIES |
| To: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| MP-1-1667, MP-2-4540, NUDOCS 8108060345 | |
| Download: ML20030B338 (3) | |
Text
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July 2, 1981 Docket Nos. 50-245 50-336
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U.S. Nuclear Regulatory Commissioa 631 Park Avenue King of Prussia, PA 19406
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Reference:
Facility Operating License Nos. DPR-21 and DPR-65 ETS-NR/50-245/50-336/81-01
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 yours, l
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. Mroczka U l
Station Superintendent Millstone Nuclear Power Station EJM/RAC: ail l
Attachnent cc: Director, Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, DC 20555 (17) f S'fr 8108060345 810702 PDR ADOCK 05000245 S
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O Facility:
Millstone Nuclear Power Station Report Number:
ETS-NR/50-245/50-336/81-01 Report Date:
July 2, 1981 Occurrence Date:
May 27, 1981 DESCRIPTION OF OCCURRENCE:
The following levels of Ag-110m and Co-60 activity were observed in the second quarter sample of oysters f rom within 500 feet of the discharge and this exceeded the control station average activity by greater than a factor of ten.
Analysis Sample Report Results Results Date Date (pCi/g)
(pCi/g)
Ag-110m Co-60 Control Stations -
Average of Giants Neck 5/27 6/15 010.03 010.02 and Golden Spur Within 500 feet of discharge 5/27 6/15 2.710.2 0.4210.09 6/22*
3.410.4 0.510.2
- Confirmation Recount PLANT OPERATING CONDITIONS PRIOR TO OCCURRENCE:
Millstone Unit 1 - Was shutdown since April 21, 1981 for turbine repairs.
Millstone Unit 2 - Operated at close to 100% power for April and May except for a shutdown from May 5 to dby 18, 1981.
CAUSE OF OCCURRENCE:
The levels of activity reported above are typical of levels observed during the past few years and are due to the normal discharges from the station. The levels observed in the oysters fluctuate from quarter to quarter as does the amount of Ag-110m and Co-60 in station releases and typically about one or two similar reports are required each year.
CORRECTIVE ACTION:
Since the observed levels result in potential doses well within the design objectives of 10CFR50 Appendix I and since station releases are within all required curie limits, it has been determined that
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l no operational or design changes are necessary.
In order to prevent future overconservative reporting requirements, proposed radio-logical effluent Technical Specifications have been submitted which will result in more realistic and meaningful sampling locations and reporting criteria.
l DOSE CONSEQUENCE:
Although the existence of natural oysters in this area is sparse, a dose calculation (per Regulatory Guide 1.109 method) was per-formed, assuming an individual could have consumed shellfish having the Co-60 and Ag-110m concentrations as observed for the period of one quarter of a year. This results in a calculated dose to the critical organ, which in this case is the gastrointestinal tract-lower lacge intestine of 0.25 millirem / quarter. This is a small fraction (0.0083) 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 conservativelt designed. Outside of the discharge channel, the plant discharges are rapidly diluted by the Long Island Sound to below detectable levels. Thus the concentrations of radioactivity fron the station are much less at locations accessible to the public outside of the quarry. The monitoring program at these locations verifies this.
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