ML20207F715
| ML20207F715 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 12/31/1998 |
| From: | NORTHERN STATES POWER CO. |
| To: | |
| Shared Package | |
| ML20207F696 | List: |
| References | |
| NUDOCS 9903110313 | |
| Download: ML20207F715 (5) | |
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Attachment B i
i Off-Site Radiation Dose Assessment for January-December 1998 l
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1 NORTHERN STATES POWER COMPANY q
MONTICELLO NUCLEAR GENERATING PLANT l
Off-Site Radiation Dose Assessment for January 1,- December 31,1998 l
An assessment of radiation dose due to releases from the Monticello Nuclear Generating Plant during 1998 was performed in accordance with the Technical Specifications. Computed doses were well below the 40 CFR 190 Standards and 10 CRD 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 Efiluent Release Reports for 1998.
i Off-Site Dose 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.
Off-Site Doses from Liquid Releases (T.S. 6.7.A.4) i Doses from liquid releases are listed in Table 1.
Dose to Individuals Due to Their Activities Inside the Site Boundary (T.S. 6.7 A.4)
There are several groups of concern, contract tree trimmers clearing transmission lines, sportsmen entering the Monticello site for recreational activities and Northern States Power Company transmission and distribution crews working in the substation. Use of 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 inside the site boundary by these groups would conservatively represent the most exposed individual. The annual whole body, skin and organ dose was computed using plant stack and i
reactor building X/Q values for the EPA field station location (a bounding location due to predominant wind direction and nearness to the release points) as input to the GASPAR code. This computed dose was reduced by the factor of 40/168 to account for limited occupancy. Dose the whole body, skin and organ (thyroid) are reported in Table 1.
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Doses to the Likely Most Exposed Member of the General Public from Reactor Releases and Other Nearby Uranium Fuel Cycle Sources (T.S. 6.7.A.4)
There are no other uranium fuel facilities in the vicinity of the Monticello s te. The only 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. This data indicates that the annual whole body and organ dose to each of these locations is less than IS millirem.
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 es: cess of 40 CFR 190 standards of 25 millirem to the whole body,75 millirem to the thyroid, and 25 millirem to any other organ.
Changes in Land Use and Non Obtainable Milk or Vegetable Samples (T.S. 4.16.B.2 & T.S. 4.16.A.5)
There were no changes in land use resulting in significant increases in calculated doses. There were no milk or vegetable samples that could not be obtained during this reporting period.
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Table 1 Off-Site Radiation Dose Assessment - Monticello PERIOD: January 1, through December 31,1998 l
Maximum Site Boundary Beta Air Dose l
(mrad / year) l 0.158 20 l
Maximum Off-Site Dose to Any Organ l
(mrem / year) l 0.050 15 Maximum Dose to the Likely Most Exposed Member of the General Public (mrem / year)
Whole Body 0.003 5
Skin 0.003 15 0.007 15 Organ (Thyroid) l Maximum oft-Site Dose (mrem)
Whole Body 0.000 3
Organ 0.000 10 Page 3 of 4
Table 2 Off-Site Radiation Dose Assessment -Monticello Supplemental Information PERIOD: January 1, through December 31,1998 Maximum Site Boundary Dose Location (from Reactor Building Vents)
Sector SSE Distance (miles) 0.40 EPA Field Station Sector SE Distance from Plant Stack (miles) 0.26 Distance from Reactor Building Vents 0.36 Maximum Off-Site Dose Location Sector SSW Distance (miles) 0.70 Pathways Plume, Ground, Inhalation, Vegetable Age Group CHILD TIIYROID l
Organ Maximum Off-Site Dose Location Downstream ll 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