Radiological clearance of historical waste from particle accelerators

Abstract

This paper presents a detailed methodology for reclassifying radioactive material from particle accelerators as non-radioactive, drawing on experiences at CERN. During particle accelerator decommissioning, the waste is classified based on its radioactivity level where the very-low-level activity material is the potential clearance candidate. Complying with the Swiss legislation, the waste must fulfill three criteria in order to be cleared. Before performing the radiological measurements, the waste must be processed (disassembled, cut, … ) due to its size and multi-material composition. To properly evaluate the measurement results, a detailed theoretical study must be performed providing information on e.g. expected radionuclides. As a part of quality assurance, the theoretical models are verified using gamma spectrometry measurements on waste samples. The presented methodology is supported by the summary of past and ongoing CERN projects as well as know-how learned by years of experience.