Effect of Collimator Elements on the Beam Spectrum and KERMA In Gamma Irradiator

In the development of low-medium energy photon calibration facilities we have simulated several types of gamma irradiator collimator materials with ISO 4037-1 design connected to the output beam spectrum and the resulting kerma. Four types of collimator material, namely Al, Fe, Pb, and WCu have been simulated with gamma radiation sources 241Am, 57Co, 137Cs, and 60Co. Simulations were carried out using the Monte Carlo method with the PHITS computer program. Based on the comparison of air kerma produced, collimators made from Al are suitable for gamma sources 241Am, Fe material for gamma sources 57Co, and Pb material for sources 137Cs and 60Co.

PLANAR SCINTIGRAPHY IMAGE DE-NOISING USING COIFLET WAVELET

The planar scintigraphic image usually has poor resolution and contains noise. This noise can be removed using the coiflet wavelet method so that the image quality gets better. This coiflet wavelet method is a noise reduction method based on frequency analysis. The planar scintigraphy image is the reconstructed image of the gamma radiation count data (phantom with the Cs-137 source in it). The original image is 15×15 pixel. Before the de-noising process, the image went through an interpolation process, which is to increase the pixel size of the image. The original image enlarged to 70×70, 480×480, and 1200×1200 pixel. After de-noising with coiflet wavelet, the image quality is measured based on MSE and PSNR parameters. The resulting images are quite good, with MSE values are close to zero and PSNR values of more than 60 dB. The smaller the MSE and the bigger the PSNR, is getting the better the image quality. In this study, the results show that the 1200×1200 pixel image has the best quality. It means that the image enlargement process has a good effect on the de-noising process, especially if the original image has a low resolution.

Preliminary Study on Minor Actinide Incineration in RSG-GAS without Isotope Separation

Minor actinides (MA) resulted from nuclear power plants is often considered as nuisance in spent fuel management due to its considerably long half-life. One of available strategies to deal with MA is to incinerate it, in order to reduce its radioactivity. This paper presents a study on MA incineration in RSG-GAS research reactor. Unlike previous study, this work did not separate the MA into individual isotopes, but incinerated as a whole. ORIGEN2.1 code is employed to calculate MA incineration within RSG-GAS core. MA composition used in this study consists of Np, Am, and Cm isotopes. The Central Irradiation Position (CIP) of RSG-GAS is loaded by 6 kg of MA and irradiated for two years. The result shows that about 1 kg of MA were incinerated after two years of irradiation, or 18,87% of the initial concentration. However, the increase of Cm-242 isotope, along with newly-formed Pu isotopes, were found to be significantly increasing short-term radioactivity compared to un-irradiated MA. Thus, two years-worth of MA incineration cannot be considered as effective, and other strategies must be pursued.

A NOVEL DESIGN OF 17.5 KV HV FEEDTHROUGH FOR ARJUNA 2.0

A NOVEL DESIGN OF 17.5 KV HV FEEDTHROUGH FOR ARJUNA 2.0. A novel design of the 17.5 kV feedthrough for Arjuna 2.0 Cockcroft Walton generator has been proposed. It is used for connecting the output of RF transformer oscillator (in the outside of horizontal vessel) with the input of voltage multiplier (inside of horizontal vessel) of the Cockcroft Walton generator. It was equipped by covers on left and right side. The designed feedthrough was simple, compact, easy to manufacture, high performance to prevent flashover and also it was applied to Arjuna 2.0 Cockcroft Walton. It was made from teflon (PTFE) and solid copper, which have high dielectric strength, capable of withstanding press loads, and easy to manufacture. The shortest distance between grounding with conductor radially was 43.25 mm, and 253.5 mm for feedthrough surface. The design was verified by Finite Element Method software and continued with performance testing. According to simulation, the stress of voltage is high about 16 kV to 17.5 kV on feedthrough conductor and 0 to 3 kV on feedthrough flange. The electric field of the covered feedthrough is lower than the coverless feedthrough. The highest and lowest electric fields are 1.26 x 106 V/m and 1 x 105 to 2 x 105 V/m respectively. Furthermore, feedthrough has been tested up to 120 kV and no discharge occurred. It means this design can be operated for 17.5 kV and it was successful installed on Arjuna 2.0 Cockcroft Walton generator.