Residual radioactivity assessment in nuclear power plants: concentrations, distribution inventories

A research program is being conducted for the USNRC to provide a data base of residual radionuclide concentrations in commercial nuclear generating stations. The data sampling has been conducted at six sites. The measurement program has been completed for two of the the sites. A topical report has been preapred describing the findings at the first site (Pathfinder). The report detailing the findings at the second site (Humboldt Bay) is in preparation. The findings to date indicate no significant radionuclides have been forgotten which might pose additional problems at the time of decommissioning. They also indicate that each reactor site will have a unique set of circumstances associated with its operating history. As examples, Humboldt Bay had an early history of fuel failures which may lead to tramp fuel and fission products spread more widely than at other sites. At Pathfinder the failed superheater led to deposition of vessel-derived metal pieces into piping creating local hot spots of very high radiation levels. The data in this report and the subsequent topical reports describing each reactor site should provide the USNRC an appropriate data base for residual radionuclide concentrations and distributions in commercial power reactors. Using this data base, proper decommissioning assessments can then be made. 7 references, 6 figures, 8 tables