Nondestructive radioassay for waste management: an assessment

Abstract

Nondestructive Assay (NDA) for Transuranic Waste Management is used to mean determining the amount of transuranic (TRU) isotopes in crates, drums, boxes, cans, or other containers without having to open the container. It also means determining the amount of TRU in soil, bore holes, and other environmental testing areas without having to go through extensive laboratory wet chemistry analyses. it refers to radioassay techniques used to check for contamination on objects after decontamination and to determine amounts of TRU in waste processing streams without taking samples to a laboratory. Gednerally, NDA instrumentation in this context refers to all use of radioassay which does not involve taking samples and using wet chemistry techniques. NDA instruments have been used for waste assay at some sites for over 10 years and other sites are just beginning to consider assay of wastes. The instrumentation used at several sites is discussed in this report. Almost all these instruments in use today were developed for special nuclear materials safeguards purposes and assay TRU waste down to the 500 nCi/g range. The need for instruments to assay alpha particle emitters at 10 nCi/g or less has risen from the wish to distinguish between Low Level Waste (LLW) and TRU Waste at the defined interface of 10 nCi/g. Wastes have historically been handled as TRU wastes if they were just suspected to be transuranically contaminated but their exact status was unknown. Economic and political considerations make this practice undesirable since it is easier and less costly to handle LLW. This prompted waste generators to want better instrumentation and led the Transuranic Waste Management Program to develop and test instrumentation capable of assaying many types of waste at the 10 nCi/g level. These instruments are discussed.