Estimating minimum detectable concentrations achievable while scanning building surfaces and land areas.

Scanning is performed during radiological surveys to identify elevated levels of direct radiation. The levels detected depend on the surveyor's abilities and decision processes. A method is described for anticipating levels that surveyors might reasonably be expected to detect in scanning by estimating the increment in a survey instrument's counting rate that would be necessary to support specified limits on Type I and Type II error rates, taking into account the fact that human beings typically do not operate with perfect efficiency. The result is applied to calculations of minimum detectable concentrations (MDCs) achievable while scanning structure surfaces and land areas. The approaches used for determining scan MDCs are provided, along with examples for common radionuclide contaminants and field survey instrumentation.

Decommissioning of a university research reactor.

The objective of the UCLA Boelter Reactor Decommissioning Project was the release of the Boelter reactor facility for unrestricted use. The facility included a 100 kW Argonaut type research reactor that operated from 1963 to 1985, providing general reactor research. The decommissioning was planned as a two-phase program. Phase I involved removal of the reactor core structure for better access and assessment of the biological shield. Phase II decommissioning activities included structural steel removal, activated concrete removal, process equipment pit piping dismantlement, and clean concrete removal. The final release survey of the Boelter reactor facility demonstrated that all areas satisfied the project's release criteria. The total person-Sv for the project was 3.87 x 10(-2) (3.87 person-rem), most of which was received during the structural steel and activated concrete removal tasks and the disassembly of the reactor core.