Moderator, Collimator And Shielding Studies For Bnct Research At Malaysian Nuclear Agency
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Date
2016-03
Authors
Mohd Solleh, Mohd Rafi
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
The objective of this research is to optimally study an arrangement for BNCT facility at a beam line through the thermal column of Malaysian TRIGA MARK II Reactor. There is no similar research had been done at this thermal column and all TRIGA reactors have different characteristics. The characteristics of the neutron beam needed are thermal neutron with a flux of 109 cm-2s-1 and the diameter of the beam is 15 cm. Collimator, moderator and shielding components with reactor core and thermal column were simulated with Monte Carlo N-Particle Transport Code. Fluxes of neutron and photon were calculated together with their energies with the same software. After that, collimator and shielding are fabricated. For fast and epithermal neutron shielding, a polyethylene and water were used. For gamma-ray shielding, lead was used. The collimator is made from polyethylene pipe with 8 cm of diameter filled with paraffin. Neutron and gamma-ray measurement in a Central Graphite Stringer (G7) of thermal column was done with TLD detectors. At 1 MW of reactor power, gamma-ray dose rate was 30.67 Svhr-1 and neutron flux was 1.69 × 1010 cm-2s-1. Neutron and gamma-ray fluxes in shielding box were measured with TLD also. Gamma-ray dose rate was 1.41 Svhr-1. Neutron flux was 3.00 × 107 cm-2s-1 which is lower than needed neutron flux. In order to study neutron penetration in human body, an experiment with water phantom was conducted. Neutron flux was 5.00 × 106 cm-2s-1 at 0.0 cm depth and 3.00 × 107 cm-2s-1 at the depth of 0.8 cm and then decreased to 1.00 × 106 cm-2s-1 at the depth of 8.1 cm. Neutron spectrum measurement was done with MICROSPEC-2. The spectrum obtained was as expected. The highest spectrum count was around thermal neutron energy and decreasing as neutron energy increased. The experiment is continued with a cadmium plate, B4C plate, lead plate, water in aluminium case and ice in aluminium case were placed at the front of MICROSPEC-2. Ice had produced thermal neutron of 0.05 counts per second. Water produced 0.04 counts per second. The conclusion of this study is that the thermal column of Malaysian TRIGA MARK II reactor is sufficient to be used in cancer treatment based on BNCT method.
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Keywords
Neutron