Criticality Accident Dosimetry cont'd - doe-std-1128-98

DOE-STD-1128-98

The criticality accident program should contain the following items:

a method and procedure to conduct an initial screening of individuals

involved in a nuclear accident to determine whether significant exposures

to radiation occurred (10 CFR 835.1304(b)(1))

methods, procedures, and equipment for obtaining and analyzing biological

materials (including 24Na activity from blood samples and 32P activity in

the hair)(10 CFR 835.1304(b)(2)), as well as metal coins, jewelry, and

articles of apparel that may have become activated from neutrons

a system of fixed dosimeters (i.e., NADs) (10 CFR 835.1304b(3)) capable

of furnishing estimated radiation dose within an accuracy of 25% and the

approximate neutron spectrum at the installed locations to allow

conversion from rad to rem

an operating range for the fixed dosimeters' neutron component 10 rad to

10,000 rad

measurement capabilities for the fixed dosimeters' gamma ray component

of fission gamma rays in the presence of neutrons with an accuracy of

20%, and an operating range for the gamma component operating range

extending from 10 rad to 10,000 rad

PNADs capable of furnishing sufficient information to determine neutron

and gamma dose with an accuracy of 25% over a range of 10 rad to 1000

rad without dependence upon fixed NAD data

a radiological counting laboratory with the methodology, analytical

procedures, and quality assurance program in place to count the activated

samples from the criticality accident and provide results quickly

counting of activities in persons with significant exposures to assess the

activation products in the body if a whole body counter is available (this is

one of the more accurate methods for dose estimation)

a health physicist designated to coordinate and evaluate the dosimetry

information and provide dose estimates shortly after the accident

a quality assurance program in place to help assure the accuracy and

validity of the dosimetry results.

As mentioned in Section 6.1, the concept of dose equivalent was used to quantify

exposures to different radiations. The quality factors used to determine dose

equivalent are based on stochastic effects, primarily cancer induction some years

later. But the doses in criticality accidents are typically so large that acute

symptoms, including death, may occur within relatively short times, and quality

factors are usually not applicable. For this reason, it is usually more appropriate

to determine absorbed dose rather than dose equivalent if a person receives more

than about 25 rem. These absorbed dose estimates to the torso are much more

important for triage and treatment considerations.

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