Routine Operations

DOE-STD-1136-2004

Guide of Good Practices for Occupational Radiation Protection in Uranium Facilities

7.5.1 Routine Operations

During routine operations, the radiological control staff's primary responsibility related to nuclear

criticality safety will include calibrating, repairing, and maintaining the neutron criticality alarm detectors

and nuclear accident dosimeters, and maintaining appropriate records. The radiological control staff should

be knowledgeable of criticality alarm systems, including alarm design parameters, types of detectors,

detector area coverage, alarm set-points, and basic control design. The staff should also be familiar with

locations and scenarios for designing the fixed nuclear accident dosimetry program and formulating plans

for emergency response.

The radiological control staff should maintain an adequate monitoring capability for a nuclear

criticality accident. In addition to the criticality alarm systems and the fixed nuclear accident dosimeters

discussed above, remotely operated high-range gamma instruments, personal alarming dosimeters for

engineering response/rescue teams, neutron-monitoring instrumentation (in case of a sustained low-power

critical reaction), and an air-sampling capability for fission gases shall be maintained.

Other support activities may include assisting the nuclear criticality safety engineer or operations

staff in performing radiation surveys to identify residual fissionable materials remaining in process

system or ventilation ducts.

7.5.2 Emergency Response Actions

The priorities of the radiological control staff during a criticality event should be to rescue personnel,

prevent further incidents or exposures, and quickly identify those who have been seriously exposed. To

support these emergency response actions, the radiological control staff should be trained in facility

emergency procedures. These emergency procedures include evacuation routes, personnel assembly areas,

personnel accountability, care and treatment of injured and exposed persons, means for immediate

identification of exposed individuals, instrumentation for monitoring the assembly area, and re-entry and

formation of response teams.

Emergency response procedures for conducting the initial quick-sort of workers should specify

measurement techniques and require that surveyors record methods and instrument settings used for

quick-sort operations to ensure proper interpretation of the results. Surveyors/analysts should compare

field results to pre-established activity-dose relationships developed as part of emergency response

procedures to determine if a worker was exposed. Other indicators, such as a discharged self-reading

dosimeter, could also indicate a possible exposure.

As an immediate follow-up action on workers identified as being exposed during a quick-sort

procedure, a more accurate dose estimate should be made using PNADs, fixed-location accident

dosimeters, or biological activity analyses (24Na in the blood or 32P in the hair). The more accurate

analyses should include: 1) better definition of source characteristics, 2) location of moderating

materials, and 3) location and orientation of the person(s) at the time of exposure and action of the

person following the irradiation. If the radiological control staff are involved in the rescue and initial

monitoring procedures, they can provide valuable information to support this analysis, particularly

regarding the location and orientation of workers to the exc ursion.

Radiological control staff should be responsible for retrieving fixed nuclear accident dosimeters and

ensuring that PNADs from any exposed workers are submitted for analysis.

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