Po‐Poster ‐ 14: In‐house leak testing with a multi‐channel analyzer system

Abstract

The URSA‐II Multi‐Channel Analyzer (MCA) (URSA‐II Radiation Safety Associates, Inc. Hebron, CT) connected to a NaI well counter (PR‐4112, Ludlum Measurements, Inc. Sweetwater, TX) is an ideal instrument for performing accurate assays of samples with low levels of activity. Clinically this is important for assaying leak‐test samples taken from sealed sources. Leak testing is a Canadian Nuclear Safety Commission (CNSC) licensing requirement for all sealed sources with activities exceeding 50 MBq. The URSA‐II was evaluated by calibrating the system using a set of known Co‐60 and Cs‐137 sources and then assaying a second set of known Co‐60 and Cs‐137 test sources. The measured activities for the test sources set were within ±5% of the values listed on the certificate once corrected for decay. We found the minimum detectable activity (MDA) for this instrument is 7 Bq for Co‐60 and 3 Bq for Cs‐137 when using a fixed counting time of 60 seconds. These MDAs demonstrate this instrument would have no difficulties in determining if a leak test sample is under the 200 Bq action level as dictated by the CNSC in the CNSC regulatory document R‐116 for leak testing. The URSA‐II is a convenient and simple tool for performing in‐house leak testing as part of a standard license compliance program for class II clinical installations.