ML20042F670
| ML20042F670 | |
| Person / Time | |
|---|---|
| Issue date: | 04/23/1990 |
| From: | Randy Hall, Michaud P NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| References | |
| REF-WM-39 NUDOCS 9005090226 | |
| Download: ML20042F670 (3) | |
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' NUCLEAR REGULATORY COMMISSION REolON IV g
UMANiuM RECOVERY FIELD OFF6CE
- f g,e BOX 25335 DENVER, COLORADO 31225
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'f4 APR 2 31990 e
URF0:PWM-Docket No. 40-WM039 040WM039450E MEMORANDUM FOR:
. Docket File No. 40-WM039
.FROM:
Paul W. Michaud, Project Manager s
SUBJECT:
UTILITY WORKERS HEALTH RISK ANALYSIS' d
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-Background The Department of Energy (DOE) submitted this Utility Worker Health Risk Analysis-for MC concurrence on September 8,1989. ~ The purpose of this analysis is to supplement eight previously submitted Radiological and-1 Engineering Assessments (REAs).
The Colorado Department of Health raised 1
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concerns'over the fact that exposure rates for workers in trenches could be f
_ higher than those calculated in the REAs for the-general public. The eight.
.REAs involved apply supplemental standards to leave contaminated mill tailings-l 3r in~ place around buried utility-lines..The DOE also proposesito include.the
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'j; utility workers health risk analysis in any future requests for' supplemental l
standards for utility lines.
j Discussion
' Criteria for protection of the general public'were used in evaluating-the potential gamma and radon exposure to utility workers.
A maximum gamma L
exposure'of 100 mrem /yr and a maximum radon concentration of 0.02 working level were used.
Calculations of maximum exposure time for any individual working in a l
contaminated trench were made using actual records of repairs in the city of Grand Junction for three previous years.
These records included the number of l
repairs, type of repair and time to complete.
This data was combined with a L
list'of potentially contaminated utility lines to estimate the total time that p
workers spend in contaminated trenches during a year.
1 Gamma readings and radon samples were taken from several contaminated trenches.
L From the gamma exposure rate data, the number of hours required for a person to reach the 100 mrem permissible dose was calculated.
These figures were then compared with the calculated number of hours of exposure an average worker may receive'in one year.
The results showed for the worst case gamma exposure L
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APR 2 31990 i
rate, the estimated time an individual worker will spend in contaminated trenches is 10 times less than the time required to reach the 100 mretu/yr -
limit.
It should be noted that an individual could therefore theoretically work on each contaminated repair project in an average year and still acquire less than half the permissible exposure of 100 mrem /yr.
j Data from radon' samples taken in contaminated trenches were reduced to terms of Working level Month per year.
The exposure limit of 0.02 working level equates to 1.0 Working Lavel Month per year Using the worst case radon exposure, a safety factor of 244 was achieved for individual workers.
Assuming that an individual worked on every contaminated repair project in an average year, a factor of safety of 62 would still exist.
Conclusion 4
The staff agrees with the DOE that no clear present or future health risks exist for utility workers in Mesa County, Colorado from potential gamma or radon exposure due to residual materials remaining as a result of the application of supplemental standards.
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a Michaud Ae
,r t Manager
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Approved by:
l Ramon E. Hall l
Director Case Closed:
040WM039450E cc:
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APR 2 31990 WM39/450E/PWM/90/04/17/M DISTRIBUTION Docket File No,'40-WM039 i
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-CONCURRENCE:
DATE:
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