Accidents and Dose Limits -Reply

[Roger Pedersen <RLP1@nrc.gov>]

It appears to me that some of the responses to this question have confused dose
limits with design criteria.  The design (or siting) criteria in 10CFR Part 100 and
GDC 19 in Appendix A to 10 CFR Part 50 are not dose limits.  Design criteria
determine how robust your plant design needs to be (e.g., in the unlikely event of
an accident we want reasonable assurance the consequences are no larger than ,
say 300 rem thyroid).  This is different than saying it is OK to give someone a dose
of 299 rem thyroid during an accident.  During normal operations the dose limits
are frequently used as design criteria - we want reasonable assurance that the plant
design can be operated within the dose limits.  

This question of whether 10 CFR Part 20 applies during an accident came up
several years ago.  Although the question then focused on the occupational dose
limits and emergency workers responding to an accident.  The NRC tried to clarify
its position in the 1991 revision to 10 CFR 20 by adding "However, nothing in this
part shall be construed as limiting actions that may be necessary to protect health
and safety" to the Purpose discussion in 20.1001(b).   The statements of
consideration that were published with the rule (56FR23360) state, "It is the
Commission's intent that the regulations be observed to the extent practicable
during emergencies, but that conformance with the regulations should not hinder
any actions that are necessary to protect public health and safety such as lifesaving
or maintaining confinement of radioactive material.

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                       "Our loftiest plans have fallen through, 
                          our airiest castles tumbled over,
                          because of lines we neatly drew,
                           and later neatly stumbled over."  - Piet Hein

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>>> William McCabe <WMCCABE@tnrcc.state.tx.us> 11/21/97 07:29pm >>>
I am having a discussion with our legel staff regarding accidents and
dose limits.  Our legal people are telling me that the regulatory dose
limits (100 mrem/yr as well as the 25 mrem whole body, 75 mrem thyroid,
and 25 mrem other organ to any member of the public) and effluent
concentration limits (i.e. 10CFR20, App B) and other such limits, as
applicable, apply.  Their opinion is based on how they are reading our
state equivalent of 10CFR (essentially the same as 10 CFR).   (It seems to
me that this is like saying it is agtainst the law to receive anything more
than minor cuts and bruises ANY traffic accident.)

It has always been my understanding that you cannot apply a regulatory
dose limit or effluent concentration limit to a radiological  accident.  All you
can do is plan and prepare for any reasonable or credible accident
situation and do everything you can to prevent the accident from
occurring and take action to mitigate the consequences of the accident if
it should occur.  (To continue my earlier analogy... install automobile
safety devices, design vehicle to absorb and distribute impact energy
away from passenger, require seat belt use, etc.  This will not prevent
exceeding minor cut and bruide injuries, but will (should) help minimize
more serious injuries and death).

I'd appreciate any comments and especially references and other state
and federal regulatory positions or guidance on this subject from the
RADSAFE community to help clear up either my or my legal people's (or
both our) misconceptions.

Thanks in advance.

Will McCabe
wmccabe@tnrcc.state.tx.us