05000317/LER-1979-018-04, /04T-0 on 790517:oyster Samples Showed Ag-110m at 88 Plus or Minus 5% Pci/Kg & Decreasing.May Be Caused by Depuration.No Corrective Action Required

/04T-0 on 790517:oyster Samples Showed Ag-110m at 88 Plus or Minus 5% Pci/Kg & Decreasing.May Be Caused by Depuration.No Corrective Action Required

ML19289F382
Person / Time
Site:	Calvert Cliffs
Issue date:	05/31/1979
From:	Eherts R BALTIMORE GAS & ELECTRIC CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML19289F379	List: 05000317/LER-1979-018, Forwards LER 79-018/04T-0 05000317/LER-1979-018-04, /04T-0 on 790517:oyster Samples Showed Ag-110m at 88 Plus or Minus 5% Pci/Kg & Decreasing.May Be Caused by Depuration.No Corrective Action Required
References
LER-79-018-04T, LER-79-18-4T, NUDOCS 7906070301
Download: ML19289F382 (2)

LER-1979-018, /04T-0 on 790517:oyster Samples Showed Ag-110m at 88 Plus or Minus 5% Pci/Kg & Decreasing.May Be Caused by Depuration.No Corrective Action Required

Event date:
Report date:
3171979018R04 - NRC Website

text

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LICENSEE EVENT REPORT CONTROL BLOCK: [

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9 UCENSEE CODE 80 74 75 PEPORT O ATE Ev",y W@]61 68 69 EVENT DATE DOCKER NUMSER EVENT oESCRIPTioN AND pro 8ABLE CONSEcuENCES hfrom the Camo Canov location an 60 d

I 03/22/79 I Oyster samoles collected on ifica tion,

j i as reauired by Section 3.2, Aopendix B, Environmental Technical Soec 1

Backoround location showed An-110m at less ishowed Ag-110m at 88 + 5!, oCi/kg.

1 Based on the observed levels, averace individual doses to the GI 2.5 pCi/kg.

j Tract and Whole Body are very small fractions of the allowable doses to mem 1

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LICENSEE EVENT REPORT 79-18/4T DOCKET NO. 50-317 REPORT DATE 05/31/79 EVENT DATE 05/17/79 ATTACHMENT EVENT DESCRIPTION AND PROBABLE CONSE00ENCES:

(CONT)

The oyster samples were collected on March 22, 1979 from the Camp Canoy sampling location and analyzed for aamma-emittino radionuclides as required by Section 3.2 Appendix 3 Environmental Technical Specifications.

The results of the analyses showed the presence of Ag-110m at 88 + 5%

pC1/Kg(wet). The oyster samples collected on the same date from the Kenwood Beach sampling location (the backaround location) showed Ac-110m atf2.5pCi/Kg(wet).

Based on the observed levels of Ag-110m during March,1979, for an average individual consuming 50 grams of oysters per day, the dotes to the GI Tract and Whole Body are estimated at 61.2 x 10-2 mrem / year and63.6 x 10-5 mrem respectively. These are very small fractions of the allowable 25 mrem /

year (GI Tract) and 25 mrem / year (Whole Body) doses to members of the general public, (40CFR Part 190 Envimnmental Radiation Protection Standards for Nuclear Power Operations) and are considered to be of no consequence to the health and safety of the public.

CAU5E DESCRIPTION AND CORRECTIVE ACTION:

(CONT)

The measurable level of Ag-110m in oysters was first detected in samples collected from the Camp Cancy sampling location in June 1977. Subse-cuently, samples collected in 1977 from the same location also showed measurable levels of Ag-110m as did the samples collected in January and February 1978. These findings were reported to the NRC as required.

Tb: oyster samples collected from the Camp Canoy location from March throuch September 1978 showed an aoparent decrease in Ag-110m concentrations.

These concentrations ranged from 310 + 10% to 160 + 15% pCi/kg (wet).

The observed decrease may in large part be due to decuration even though the effluent releases from the plant during the period of interest contained small quantities of Ag-110m.

Beginning with the fourth quarter of 1978 oyster samples are no longer sent to Radiation Management Corocration (RMC) in Philadelphia for aama analyses. These analyses are dee by the Chemical Enaineering and Test Section of our Electric Test Department, using a 10% Ge(Li) with a Nuclear Data System 6600. The sample size and the count time are selected to meet the required detection capabilities for a number of radionuclides including Zr-Nb-95. As a result of this exercise, the MDL value for Ag-110m is calculated at abouts 2.5 oCi/Kg (wet), which is substantially lower than the previous average MDL value of about440 pCi/Kg (wet). On the assumption that this new MDL value of 2.5 constitutes the backcround value, the level of Ag-110n observed in Camp Canoy March 1979 sanoles exceeded the backaround.value by over a factor of 10. However, it does show a continuation of the general trend of decreasing Ao-110m activity in oysters at this location.

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