Release Criteria cont'd

DOE-STD-1136-2004

Guide of Good Practices for Occupational Radiological Protection in Uranium Facilities

Non-radioactive material can be released without an instrument survey if its documented history

ensures:

that it has never been used or stored in an area controlled for contamination purposes (i.e., a

contamination area, high contamination area, or airborne radioactivity area),

that it has never come into contact with unsealed radioactive sources,

that it has not been stored or used in a radiological buffer area (RBA) surrounding a

contamination area, high contamination area, or airborne radioactivity area.

This material may be considered to be not contaminated and an instrument survey is not necessary. A

material history release form should be used to document the release of material that is known to be free of

contamination by its history of use. If the material history release form cannot be completed, or if the

history of the material is unknown, an instrument survey must be made of the material. Material released

from RBAs around contamination areas, high contamination areas, or airborne radioactivity areas should

also be evaluated using an instrument survey.

The material evaluation process should also consider the nuclides to which the material was

potentially exposed. If the material was exposed to significant quantities of nuclides that are

difficult to detect, including tritium 14C, 125I, or 129I, an appropriate survey methodology s hould be

applied.

A scan survey for fixed contamination requires passing the detector of an alpha and a beta/gamma

survey instrument, as applicable, over the accessible surface of the material. The detector should be

moved at a constant rate that allows detection of contamination at a level equal to three times the guideline

value. If a change in the audible output of the instrument is heard, the area under the window of the

instrument should be re-surveyed using a stationary measurement for 3 to 5 seconds. If the increase does

not persist, the scan should continue. If the elevated counts persist, the material is contaminated and

should not be released. This procedure should be followed until the surface of the material has been

surveyed.

The scan survey for fixed contamination ensures that none of the material's surface is contaminated

above three times the guideline value. If no contamination above background is detected during the scan

survey, a large-area wipe survey for removable contamination should be performed. If contamination

above background is detected, then decontamination of the material should be considered and the

methodology described in this document should not be applied.

Following the scan and large-area wipe surveys, a statistical survey for fixed contamination should be

performed. The survey methodology should be used for both beta/gamma and alpha contamination, unless

only one type of potential contaminant exists in the facility. If no measurements above background are

observed, the material may be released from radiological control.

The fixed survey measurements should be chosen using random detector placements over the entire

surface of the material. It may be prudent to bias some of the measurements toward those areas that are

more likely to be contaminated, including handles, horizontal surfaces, stains, cracks, and other surface

anomalies in which foreign material typically accumulates. This type of selection bias will further increase

the confidence associated with the statistical survey method.

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