Re: Emergency Doses Allowed

[David W Lee <lee_david_w@lanl.gov>]

Greeting as well:  

	I think Scott makes a very good point which in the case of setting
emergency exposure/dose guidelines needs to be appreciated.  Even though
TEDE = CEDE + effective DE (external), the external dose portion of the
TEDE is sustained by the individual instantaneously whereas the CEDE
portion, depending upon the effective half-life of the nuclide involved, is
sustained over the upcoming 50-year period even though the total magnitude
of the CEDE is recorded on a person's exposure/dose history in the year in
which the incident occurred.  Thus, a CEDE dose is not equivalent to the
same value of an effective DE (external) dose, because a fair portion of
the CEDE has not yet been delivered to the person to whom it has, for
accounting purposes, otherwise been fully assigned.  Apples and oranges as
Scott rightfully says.  I think Scott's suggestion of expressing emergency
guidelines in terms of equivalent dose is well worth considering.  At a
minimum, however, I conclude that expressing emergency dose
limits/guidelines in terms of a single number (10 CFR 835.1302), which
could be sustained either as 100% CEDE or 100% external DE (external) is
not realistic given that both the DOE and NRC account for dose in terms of
TEDE, not just strictly external dose anymore.  Thus, it seems to me that
any emergency exposure/dose guidelines nowadays might better be stated as
separate limits/values--an upper limit of CEDE and an upper limit for
effective DE (external).  

Best regards David


At 04:14 PM 6/4/1998 -0500, you wrote:
>Greetings,
>
>Regarding the use of TEDE for emergency dose guidelines...  It's
>interesting to keep in mind what the 25 rem emergency dose guideline was
>based on.  My guess is that the 25 rem level was selected to prevent the
>observation of deterministic effects (i.e., one of the basic principles
>of radiation protection) from prompt, whole-body irradiation.  A 25 rem
>TEDE exposure from a plutonium intake (or any radionuclide delivering
>long-term, organ-specific irradiation) would almost certainly not result
>in a detectable deterministic effect.  
>
>Using the ICRP 60 guideline of a 50 rem/y  (over successive years)
>deterministic effects threshold for internal organs, the dose
>potentially causing a deterministic effect from a plutonium intake could
>be on the order of 200 rem TEDE.  With this perspective, stating
>emergency dose guidelines (or Protective Action Guidelines for that
>matter) in terms of TEDE results in apples being compared with
>oranges...  Considering the rarity of events requiring their use, maybe
>it would be better to express emergency guidelines (or PAGs) in terms of
>equivalent dose?
>
>-Scott Sorensen
>ssorensen@doeal.gov
>
>

DAVID W. LEE
Los Alamos National Laboratory
PO Box 1663, MS K483
Los Alamos, NM  87545
PH:  (505) 667-8085
FAX: (505) 667-9726
lee_david_w@lanl.gov