Re: Accidents and Dose Limits

["J. J. Rozental" <josrozen@netmedia.net.il>]

At 06:25 PM 11/21/97 -0600, you wrote:
>I am having a discussion with our legel staff regarding accidents and
>dose limits.  

>
>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.
>


Nevertheless the  inquire, was made directly to the USA Radsafers community,
for National Regulatory positions, I ask you to allow me to make some
comments,  considering international recommendations, taking into account
that  there are many Radsafers among the List not applying the American
National Regulations.  

Let us consider the ICRP recommendations -- GOING  TO ICRP 60, 1990

a)  -  Dose limits do not apply in case of intervention (see 113);
 
b) - The limitation of occupational exposure in emergencies (see 6.3.2)

(224) Occupational exposures directly due an accident can be limited only by
the design of  the plant and its protective  features and by the provision
of emergency procedures. Ideally, the aim should be to keep the doses within
those permitted in normal conditions, but, while this usually possible, it
may not always be so in serious accidents.

(225) Besides the exposures resulting directly from the accident, there will
be exposures of emergency teams   during emergency and remedial actions.
Even in serious accidents, these can be limited by operational controls. The
doses incurred are likely to be higher than in normal situations and should
be treated separately from any normal doses. Emergencies involving
significant exposures of emergency teams are rare, so some relaxation of
controls for normal situations can be permitted in serious accidents without
lowering the long-term level of protection. This relation should not permit
the exposures in the control of the accident and in the immediate and urgent
remedial work to give effective doses of more than about 0.5 Sv except for
life-saving actions, which can rarely be limited by dosimetric assessments.
The equivalent dose to skin should not be allowed to exceed about 5 Sv,
again except for life saving. Once the emergency is under control, remedial
work should be treated as part of the occupational exposure incurred in a
practice.

This means:

a) Emergency interventions that may cause doses to workers in excess of
thresholds for serious deterministic effects have a high degree of
justification when they are aimed at saving human life or preventing very
large individual doses to members of the public,  well above the thresholds
for serious deterministic effects -- Life Savings and preventing severe
consequences there is no dose limits, dose above thresholds for
deterministic effects is allowed;

b) When intervention is aimed at preventing an escalation of an accident
that might entail substantial individual or collective dose to the public,
it will probably still be justified by the expected benefit from the
mitigation  of the consequences, however, in these circumstances workers
should not be exposed to doses in excess of the threshold for serious
deterministic effects.

c) Urgent countermeasures and short term recovery operations: -- No dose
limits, all reasonable efforts should be made to keep individual doses below
100 mSv in a year;

d) Longer term recovery operations: --  Dose limits for occupational
exposure apply;

e) Dose not directly connected with the accident: -- Dose limits for
occupational exposure apply.

J. J. Rozental (josrozen@netmedia.net.il)
Israel