ML20211B765
| ML20211B765 | |
| Person / Time | |
|---|---|
| Issue date: | 09/14/1978 |
| From: | Ryan Alexander NRC OFFICE OF STANDARDS DEVELOPMENT |
| To: | Metzger J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE) |
| Shared Package | |
| ML20211B681 | List: |
| References | |
| NUDOCS 8610210108 | |
| Download: ML20211B765 (2) | |
Text
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- ch 4, UNITED STATES y.s ,a g NUCLEAR REGULATORY COMMiss10N j , f ) ** . J g WASHINGTON, D. C. 20555 t
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MEMORANDUM FOR: Jack R. Metzger Division of Fuel Facility and Materials Safety '
Office of Inspection,and Enforcement FROM: Robert E. Alexander, Chief Occupational Health Standards Branch Office of Standards Development
SUBJECT:
APPLICABILITY OF FOOTNOTE (1) 0F 10 CFR 20.103(a)(1)
TO20.103(b)(2)
This memorandum is in response to your inquiry of September 5, 1978, transmitting Region III's question on an " exception to the concentrations for tritium" in Appendix B of 10 CFR Part 20.
Footnote (1) to 20.103(a)(1) is simply an explanatory reminder that the MPC for tritium takes into account that tritiated water vapor is considered to enter the body in equal amounts by absorption through the skin and by inhalation. These intake phenomena are characteristic of the biophysics involved and apply whenever tritium exposures of this sort are considered irrespective of explanatory notes), i.e., they apply to paragraph 20.103 b)(2) as well as to 20.103(a)(1).
From the infomation in the Region III memorandum of Sept.1,1978, it
! appears that the total intake of (3 H2 O) water vapor, as determined by bioassay, was less than double the amouEt pemitted for 40 hours4.62963e-4 days <br />0.0111 hours <br />6.613757e-5 weeks <br />1.522e-5 months <br /> by inhalation alone; therefore, under the biophysical model used, the amount .
l inhaled must have been less than wo01d result from 40 MPC-hours by inhalation alone, and there would be no violation of 20.103(b)(2). If, on the other hand, it had been detemined from air-sampling and working times that a person were exposed to over 40 MPC hours of intake by inhalation alone, then, by h model, it would be assumed that the total intake for
- that person was more than double the amount by inhalation alone for 40 l- MPC-hours, and the licensee would be in violation of 20.103(b)(2).
i To sumarize in more specific tems:
) The occupational MPCa for tritium (soluble) is '5 x 10-6 Ci/mF; the occupational breathing rate is taken as 6.3 x 108 ml per quarter; then for a 13-week quarter the breathing rate per week is 8
6.3 x 10 /13 = 4.85 x 107 ml T 4.9 x 107 ml/wk 8610210108 780914 PDR I&E MISC PDR
)
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- thus, 4.9 x 10 7ml/wk x 5 x 10 -6 pCi/ml = 245 pCi/wk T 250pCi/wk -
is the maximum pemissible intake per week by inhalation alone. (Region III calculates 242 uCi/wk by not rounding off figures, but 250 is probably within the limits of accuracy for the measurements involved).
Therefore, if the total intake in a week does no* axceed about 500;JCi
("484"), i.e., 2 x 250, there is apparently no violation of the 40 MPC-hour precautionary limit on intake in 20.103(b)(2). But if the intake by inhalation alone exceeds about 250 ("242")JuCi in that time, then there is a violation since the total intake would then be greater than the limit of about 500)uCi/wk.
k (w l Robert E. Alexander, Chief Occupational Health Standards Branch Office of Standards Development
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