Tien-Ko Wang

HPGe detector efficiency calibration for extended cylinder and marinelli-beaker sources using the ESOLAN program

Abstract A personal computer based program ESOLAN has been developed for HPGe detector absolute-peak-efficiency calibration for various source-detector arrangements. The applicability of the previously developed program is limited to sources with diameter smaller than that of the detector active crystal. In this work, the ESOLAN program is modified to extend its application to sources with dimensions larger than the detector crystal, including extended cylinder and Marinelli-beaker sources.

HPGe detector absolute-peak-efficiency calibration by using the ESOLAN program

Abstract A personal computer based program ESOLAN has been developed for HPGe detector effective-solid-angle calculation. This program is very useful in constructing the absolute-peak efficiency ( ϵ p ) vs γ-ray energy ( E γ ) curves for various counting geometries. In this work, the validity of using this program for ϵ p - E γ calibration was successfully demonstrated with four individual HPGe detector systems for γ-rays in the energy range ∼ 60 keV−∼ 2.7 MeV. The overall uncertainty on the final ϵ p - E γ curves was estimated to be ∼3%.

Well-type HPGe-detector absolute-peak-efficiency calibration and true-coincidence correction

A personal-computer-based program SWELL has been developed for well-type HPGe detector effective-solid-angle calculation. This program is very useful in constructing the absolute-peak efficiency (ep) versus γ-ray energy (Eγ) curves for different sample geometries based on a pre-determined ep under a reference counting geometry. The validity of using this program for ep(Eγ) conversion was successfully demonstrated for photons in the energy range ∼20 keV–1.5 MeV; the overall uncertainty can be controlled to be within 3%. In addition, a semi-empirical method has been developed to estimate the true-coincidence correction (COI) factor for well-type HPGe detector. Results based on 60Co, 139Ce, 133Ba and 59Fe sources indicated that the estimated COI factors are in good agreement with the experimentally validated COI values.

HPGe detector true-coincidence correction for extended cylinder and Marinelli-beaker sources

Abstract A semi-empirical method is developed to estimate the γ-γ true-coincidence correction factor (COI) for extended cylinder and Marinelli-beaker sources. Compared with point sources, the true-coincidence effects for extended sources are more complicated, since not only the source-volume averaged peak and total efficiencies but also the differential-efficiency distributions within the source itself are involved. A volume-effect factor (Fv), which can be calculated by the aid of our previously developed ESOLAN program, is introduced in this work to handle these complexities. The validity of using this method was successfully demonstrated by comparing the predicted COI values with the experimentally determined values for several radionuclides.

Application of CaF2: Tm (TLD-300) dosimeter to the discrimination between alpha, beta and gamma radiation

Abstract The response of TLD-300 (CaF 2 :Tm) to α-, β-, and x- and γ-ray radiations was studied based on the peak-height ratios in glow curves of thermoluminescence. An identical annealing, storage and readout condition for all radiation types and energies is of critical importance in applying this method. The results indicate that it is possible to identify radiation energies in the range of ∼0.05 to ∼0.3 MeV for β-rays and ∼0.006 to ∼10 MeV for γ or x-rays. The α irradiation can also be recognized through glow-curve distribution. Compared with TLD-200 (CaF 2 :Dy), the energy range which can be discriminated by TLD-300 is much wider.

A personal computer based program for HPGe detector absolute-peak-efficiency calculation and calibration

Abstract A personal computer based program is developed for HPGe detector effective solid angle calculation for various source-detector arrangements. This program uses a simplified detector model to avoid tedious computational algorithms. The source geometry can be point, disk or cylinder. The applicability of using this program for gamma-ray absolute-peak-efficiency calibration has been successfully validated with various combinations of source geometry, source-detector distance and gamma-ray energy.

Feasibility studies on iterative methods of fuel burnup estimation using gamma-ray spectrometry

The aim of this work is to establish a method for spent fuel burnup estimation using non-destructive γ-ray spectrometry without the need for detailed data on fuel irradiation history. The methods thus developed are based on an iterative approach by comparison between the measured and the calculated fission product activities or activity ratios. Good agreement is obtained among the burnup values deduced from 137Cs activities, 134Cs/137Cs activity ratios, and 140La activities.

An iterative approach for TRIGA fuel burn-up determination using nondestructive gamma-ray spectrometry.

The purpose of this work is to establish a method for evaluating the burn-up values of the rod-type TRIGA spent fuel by using gamma-ray spectrometry of the short-lived fission products 97Zr/97Nb, 132I, and 140La. Fuel irradiation history is not needed in this method. Short-lived fission-product activities were established by reirradiating the spent fuels in a nuclear reactor. Based on the measured activities, 235U burn-up values can be deduced by iterative calculations. The complication caused by 239Pu production and fission is also discussed in detail. The burn-up values obtained by this method are in good agreement with those deduced from the conventional method based on long-lived fission products 137Cs, 134Cs/137Cs ratio and 106Ru/137Cs ratio.

TRIGA fuel enrichment verification based on the measurement of short-lived fission products

Abstract A method is developed to verify the 235 U content of TRIGA fresh fuel using gamma-ray spectrometry of the short-lived fission products 97 Zr/ 97 Nb, 132 I and 140 La. The short-lived fission-product activities can be established by irradiating the fuel in a nuclear reactor. Based on the measured activities, the 235 U content can be deduced by iterative calculations. The aim of this work is to establish a calibration method for estimating the burnup values of the rod-type spent fuels without the need for detailed data on fuel irradiation history.

A model for correcting for the effect of fluctuating voids in radiometric diagnosis of two-phase-flow

Abstract A simple plane model is proposed for correcting the effect of void fluctuations on void-fraction determination in two-phase-flow systems employing the modified (one-shot) photon-attenuation method. Through a series of benchmark tests, an experimental observation is that if the static void assumption is used, the experimental result will consistently exceed the actual time-averaged void fraction. The accuracy of the void-fraction prediction can be much improved by the correction procedure established in this work.