Standardization of Cd by two methods.

Cd is quite a useful nuclide for the calibration of X-ray spectroscopy, gamma-ray spectroscopy or as an excitation source in X-ray fluorescence. In this work, 4π(PC)e-X coincidence counting and 4π(LS)ce counting were used to determine the activity of the Cd solution. The two methods showed good agreement in their counting results.

Comparison exercise on activity determination of radioactive waste drums in Taiwan.

The National Radiation Standard Laboratory of Taiwan organized in 2014 a comparison exercise by distributing 210 L drum-typed samples to seven radioactive waste analysis laboratories in Taiwan. Four drums were filled with uniformly distributed active carbon, water, resin and concrete, respectively and five drums were filled with cracked metals and heterogeneously distributed radioactive sources. Measurement uncertainties of participants results are in the range 3–40% (k=2) and about 96% of the reported results produced En values (ISO, 1997) smaller than one for drums with activity uniformly distributed.

Reference drums used in calibration of a plastic scintillation counter in a 4π counting geometry.

In this study, two kinds of reference drums were developed. One type was constructed with nine layers of large-area sources filled with different materials having five different densities. The other type of reference drums was constructed with nine rod sources filled with the same materials of different densities.

Measurement and calibration of metal and non-metal wastes produced from decommissioning.

This report described a radioactive waste reference drum which was established with large-area sources and metal slices. This reference drum could be applied in calibration or testing of drum counting systems having 4π counting geometry and being made with plastic scintillators. This metal reference drum has the advantages of easy operation, low natural background and it also has agreeable measurement efficiency calibration curves for the drum counting system as the non-metal reference drum studied previously.

Proficiency test for clearance mixed-nuclide samples.

In 2010, the National Radiation Standard Laboratory held a proficiency test for measurement and analysis of clearance mixed-nuclide samples. Two types of samples, box-shape and drum-shape, containing (60)Co and (137)Cs mixed solutions were measured by the participating laboratories and their results were then compared with the reference values. Seven participants used plastic scintillator counting systems and two participants used HPGe spectrometer systems to join in this study, obtaining 40 measurement results.

Evaluating practicability of an LSC method for routine monitoring gross alpha and beta activities in water samples in Taiwan.

A procedure using liquid scintillation counting for the monitoring of gross alpha and beta activities in environmental water was implemented to improve the conventional procedure using GFPC adopted in Taiwan. The new procedure was acquired through calibration and validation, and then was applied to the monitoring of surface water in Taiwan. This procedure can improve 2-4 times of detection efficiencies and takes only 70-80% of analysis time with reliable accuracy.

The performance evaluation of a movable gamma-ray counting system for radwaste measurement.

Performance tests of a movable gamma-ray waste drum scanning system were carried out in this study. The scanner consists of a single HPGe detector on a movable cart with a 90° collimation angle to the observed item. The detection efficiency for (137)Cs was determined using the ISOTOPIC software.

Proficiency testing feasibility study for the measurement of gamma-emitting clearance samples.

A proficiency testing feasibility study program was proposed by the National Radiation Standard Laboratory (NRSL) of Taiwan to understand the capabilities of laboratories dealing with clearance measurements, and to issue related technical criteria for radioactive waste assay. In this program, twelve blind test samples with different levels of radioactivity, radionuclides and different packing densities were prepared. Seven laboratories participated in this program and fourteen instruments were tested.

The calibration and evaluation of a radioactive waste drum counting system.

The drum counting system was calibrated in this study. For (137)Cs, the counting efficiencies were around 14-1% when the density of the waste of the drum was changed from 0.15 to 2.