Implementing an operational program for determining the radiological status of material and equipment

摘要

The National Ignition Facility at the Lawrence Livermore National Laboratory has implemented a protocol for evaluating and releasing material and equipment that is potentially "volumetrically contaminated" as a result of neutron activation and shown not to be "distinguishable from background." This protocol is an important element of the National Ignition Facility's operational program as the U.S. Department of Energy's (DOE) Order 458.1, Radiation Protection of the Public and the Environment, requires DOE approval of the process used to release volumetrically contaminated personal property and establishes a dose constraint of 10 μSv y-1 (1 mrem y-1) for clearance of such items. The protocol uses process and historical knowledge to determine when material and equipment may be potentially impacted and field measurements to verify it has been impacted (i.e., is distinguishable from background). Material and equipment that do not meet the distinguishable-from-background criterion are considered to be non-impacted and outside the scope of the Order and may be released from radiological control. This paper provides the technical basis and methodology for determining whether or not there is radioactivity distinguishable from background in the evaluated material and equipment and documents that the measurement sensitivity exceeds the unrestricted release criteria specified in the American National Standards Institute report N13.12-1999, Surface and Volume Radioactivity Standards for Clearance. Pending DOE approval, this protocol could be used as the basis for releasing materials and equipment that exceed the distinguishable-from- background criterion and are below the specified threshold for unrestricted release.