Proposed new method of characterizing large volumes of low-level waste by direct liquid scintillation spectroscopy of filter paper test smears

摘要

A proposed method of characterizing radionuclides in Low-Level Waste (LLW) based on liquid scintillation spectroscopy (LSS) of smears has been developed. This method was developed to confirm a priori knowledge of LLW which is too low in contaminants for direct measurements. LSS provides a fingerprint of the smear's alpha and beta energy distribution which can be compared to the inventory of known or suspected radioactive contaminants in the waste based on process knowledge/history. The major isotopes and type of nuclear material contaminating the waste can be determined from the internal consistency between experimental data and the suspected radionuclide distribution. Armed with this information, the detailed isotopics usually known for the nuclear material type, and some bounding assumptions about age and contamination levels, all other radionuclides required for complete characterization of the waste can be calculated. This approach should prove cost effective in meeting the very low levels stemming from radiological performance assessment requirements mandated for new disposal facilities. Many of these levels are 4--5 orders of magnitude more restrictive than 10CFR61, and are virtually impossible to meet through actual measurements for many types of wastes.