Nuclear Accident Dosimetry - STD-1128-98master0216

DOE-STD-1128-98

Guide of Good Practices for Occupational Radiological Protection in Plutonium Facilities

power. Each alarm system should be tested at least once every three months. An evacuation

drill shall be conducted at least annually.

Criticality alarm systems may consist of one to several detectors per unit. In multi-detector

units (e.g., three detectors), at least two detectors shall be at the alarm level before initiating

the alarm; in redundant systems, failure of any single channel shall be into the trip state

(ANSI, 1986a).

7.4.2 Nuclear Accident Dosimetry

In accordance with DOE Order 420.1A, the nuclear criticality safety program shall be

evaluated and documented and shall include:

Assessment of the need for criticality accident detection devices and installation of such

equipment where total risk to personnel will be reduced.

Nuclear accident dosimetry is required when the fissionable material mass exceeds the

ANSI/ANS-8.3 limits discussed in Section 7.4.1 and the probability of criticality is greater

than 10-6 per year.

Requirements for nuclear accident dosimetry programs at DOE facilities are found in

10 CFR 835.1304 (DOE, 1998a). A nuclear accident dosimetry program shall include the

following:

-- A method to conduct initial screening of personnel involved in a nuclear accident to

determine whether significant exposures to radiation occurred;

-- methods and equipment for analysis of biological materials;

-- a system of fixed nuclear accident dosimeter units (sometimes referred to as area

dosimeters); and

-- personnel nuclear accident dosimeters (PNADs) worn by all individuals who enter

locations with specified quantities of fissile material.

Additional desirable features of a nuclear accident dosimetry program include:

-- Facilities to evaluate fixed dosimeters and/or PNADs;

-- a method to determine the approximate neutron spectrum;

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