Technical Management Assessment Guide to Historically Solid Radioactive Materials (Classes LLW and ILW): Case Study of the Greek Nuclear Research Reactor (GRR-1)

Abstract

The purpose of this work is the radioactive control of long-term-stored materials [historically radioactive waste, Types LLW (low-level waste) and ILW (intermediate-level waste)] in an interim storage room at a nuclear research reactor facility in Greece and their segregation into radioactive and cleared materials based on the dose rate and their surface contamination. The radioactive materials were spectroscopically evaluated to assess types of radionuclides and their activity. The results indicated that of the 122 stored items, 102 were classified as cleared materials and were removed for recycling, while 20 were spectroscopically evaluated as radioactively contaminated with 60Co (1,332 and 1,173 keV) and 137Cs (661 keV) and remained in storage. Exposure of the staff to radiation during the procedure was moreover assessed, and the dose was found between 0.7 and 7.5 μSv/day. These radiation exposure values were lower than the set local dose limit of 500 μSv set by the radiation protection officer for the duration of the work and significantly lower to the annual dose constraint of the facility of 6 mSv. Moreover, dose rates to nonhuman biota are, on the other hand, several orders of magnitude below the screening limit. Hence, we conclude with high confidence that by protecting humans the environment is also protected in this case. The main scientific contribution of this paper is to serve as a guide for handling stored historically radioactive materials in an interim storage room of a nuclear research reactor upon the criteria of (1) minimum radioactive exposure of staff; and (2) protecting biosystems against the potential disposal of radioactively contaminated materials therein.