ML20216B792

Off-Site Radiation Dose Assessment for Jan-Dec 1997

ML20216B792
Person / Time
Site:	Monticello
Issue date:	12/31/1997
From:	NORTHERN STATES POWER CO.
To:
Shared Package
ML20216B750	List: ML20216B745 ML20216B762 ML20216B792
References
NUDOCS 9803130187
Download: ML20216B792 (5)

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4 Attachment B Off-Site Radiation Dose Assessment for January-December 1997 (The attached Report contains 4 pages.)

2/26/90 518 Ji\ LICENSE \ PERIODIC.RPT\EFFJtPT.972

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~ NORTHERN STATES POWER COMPANY MONTICELLO NUCLEAR GENERATING PLANT Off Site Radiation Dose Assessment for January 1,- December 31,1997 An assessment of radiation dose due to releases from the Monticello Nuclear Generating Plant during 1997 was performed in accordance with the Technical Specifications. Computed doses were well below the 40 CFR 190 Standards and 10 CFR Part 50, Appendix I Guidelines.

Off-site dose calculation formulas and meteorological data from the Off-site Dose Calculation Manual were used in making this assessment. Source terms were obtained from the two Semi-Annual Effluent Release Reports for 1997.

Off Site Doses from Gaseous Releases (T.S. 6.7.A.4)

Computed doses due to gaseous releases are reported in Table 1. Critical receptor location and pathways for organ doses are reported in Table 2. Doses, both whole body and organ, are a small percentage of Appendix I Guidelines.

oft-Site Doses From Liauld Releases (T.S. 6.7.A.4)

Doses from liquid releases are listed in Table 1.

Doses to Individuals Due to Their Activities Inside the Site Hounden (T.S. 6.7.A.4)

There are two groups of conecm, sportsmen entering the Monticello site for recreational activities and the Environmental Protection Agency Field Station located at the Monticello site (see Figure 3.8.1 and 3.8.2 of the Monticello Technical Specifications). While the EPA station is no longer operational, workers occasionally visit this field station. Using a very conservative assumption of 40 hours4.62963e-4 days <br />0.0111 hours <br />6.613757e-5 weeks <br />1.522e-5 months <br /> / week spent at the EPA station would result in a dose greater than that for sportsmen and would conservatively represent the most exposed individual. The annual whole body, skin and organ dose was computed using plant stack and reactor building vent X/Q values for the Field Station location as input to the GASPAR code. This computed dose was reduced by the factor of 40/168 to account for the limited occupancy at this location. Dose to the Whole Body, Skin and Thyroid are reported in Table 1.

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e s Doses to the Likelv'Most Exposed Member of the General Public from Reactor Releases and Other Nearby Uranium Fuci Cvele Sources (T.S. 6.7.A.4)

There are no other uranium fuel facilities in the vicinity of the Monticello site. The only other artificial source of exposure to the general public in addition to the plant effluent releases is from direct radiation of the reactor and the steam turbines.

Environmental TLDs were used to provide data on direct and skyshine radiation dose and the GASPAR code was used to provide data on dose from airborne pathways. The net dose from the TLDs was added to the GASPAR dose data for locations of off site residences and the EPA Field Station. This data indicates that the annual whole body and organ dose to each of these locations is less than 10 mill.irem.

Therefore, the likely most exposed member of the general public will not receive an annual radiation dose from reactor effluent releases and all other fuel cycle activities in excess of 40 CFR 190 standards of 25 mrem to the whole body,75 mrem to the thyroid, and 25 mrem to any other organ.

Channes in Land Use and Non Obtainable Milk or Venetable Samples T.S. 4.16.B.2 There were no changes in land use resulting in significant increases in calculated doses.

T.S. 4.16.A.5 This specification requires a report that describes when milk or leafy green vegetables can no longer be obtained from the designated sample locations, and actions to identify new locations to ensure adequate sample collection. There were no milk or vegetable samples that could not be obtained. However, also see paragraph below.

T.S. 6.7.A.4 The last paragraph of this section requires a report when milk samples can not be obtained as required by Table 4.16.1. Table 4.16.1 requires gamma isotopic and I-131 analysis of each sample.1-131 analysis was not performed on the milk samples collected the week of July 28 due to a delay associated with the UPS strike.

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Table 1 Off Site Radiation Dose Assessment - Monticello PERIOD: January 1, through December 31,1997 Maximum Site Boundary Beta Air Dose I (mrad / year) 0.243 20 Maximurn Off-Site Dose to Any Organ l l l (mrem / year) l 0.023 l 15 EPA Field Station (mrem / year)  !

Whole Body 0.002 5 Skin 0.003 15 Organ (Thyroid) 0.003 15 Maximum Off-Site Dose (mrem)

Whole Body 0.000 3 Organ 0.000 10 Page 3 of 4

1 4 0 Table 2 Off-Site Radiation Dose Assessment - Monticello SupplementalInformation PERIOD: January 1, through December 31,1997  !

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Maximum Site Boundary Dose Location l (from Reactor Building Vents) l Sector SSE l Distance (miles) 0.40 EPA Field Station

, Sector SE l I Distance from Plant Stack (miles) 0.26 j Distance from Reactor Building Vents 0.36 i Maximum Off-Site Dose Location I Sector SSW m

Distance (miles) 0.70 Pathways Ground, Inhalation, Vegetable Age Group CHILD Organ THYROID Maximum Off-Site Dose Location Downstream Pathways Drinking Water Drinking Water, Fish Age Group Infant Adult Organ Whole Body GI Tract Dilution Factor (drinking water) 7.1 7.1 Page 4 of 4