In FR Notice of Final Rulemaking (67FR16289;April 5,2002),the NRC discussed the NCRP recommendations published in NCRP 130 and Statement No.9. The NRC staff said that the recommended observational level for a DRP exposure of 10 rem (0.1 Sv) is well below the new limit of 50 rem (0.5 Sv) averaged over 10 cm2. It is essentially equivalent to the former skin dose limit, at which no clinically significant effects have ever been reported. The NCRP stated in Report No. 130 that based on extensive research at BNL and elsewhere, at the new limit few if any effects are expected to be observed, and those effects would be transient in nature. NCRP further stated that if effects are observed from a DRP exposure, the result is an easily treated medical condition involving an extraordinarily small stochastic risk.
For these reasons, and to avoid unnecessary regulatory burden, the staff did not incorporate the NCRP recommendation for medical observation into the new rule. The staff did note in the FR Notice that the NCRP reports addressed this and other "good practices" that might be useful in controlling skin doses.
>>> m.w.charles@bham.ac.uk 07/18/02 06:29AM >>>
Recently Alan Roeklein kindly circulated the NRC summary regarding the
skin dose limit in 10 CFR part20. This essentially increases the averaging
area from 1 cm2 to 10 cm2 but keeps the dose limit of 0.5 Sv fixed. The
summary follows closely the NCRP statement 9 (March 30, 2001) - although
this is surprisingly not mentioned in the statement. However, the NRC
summary does not include an important part of the NCRP recommendation -
in the event of the skin dose exceeding 0.1 Gy averaged over an area of 10
cm2 the area should be observed for 4-6 weeks. At the new dose limit -
which is effectively 5 Sv averaged over 1 cm2 - there is about a 50%
probability of a skin lesion from a hot particle (NCRP 130).
Does anyone know why the NRC have not implemented the NCRP
recommendations in full? I believe that NRC deliberations are sometimes
recorded and publicly available. If there is any recorded discussion on this
topic please can anyone direct me to it?
Many thanks
Monty Charles
Dr Monty Charles, Reader in Radiation Physics
Head of Radiation Biophysics Group
School of Physics & Astronomy
University of Birmingham, Edgbaston
Birmingham B15 2TT, England
M.W.Charles@bham.ac.uk
TEL +44 0121 414 3483
FAX +44 0121 414 4725
-----------------------------------
Reply to: powernet@hps1.org
If Questions, contact Mike Russell, CHP at russelmj@songs.sce.com
************************************************************************
You are currently subscribed to the Radsafe mailing list. To unsubscribe,
send an e-mail to Majordomo@list.vanderbilt.edu Put the text "unsubscribe
radsafe" (no quote marks) in the body of the e-mail, with no subject line.
You can view the Radsafe archives at http://www.vanderbilt.edu/radsafe/