Development and characteristics of the HANARO neutron irradiation facility for applications in the boron neutron capture therapy field

Abstract

Abstract. The HANARO ex-core neutron irradiation facility was developed for various applications in the boron neutron capture therapy (BNCT) field, and its characteristics have been investigated. In order to obtain a sufficient thermal neutron flux with a low level contamination of fast neutrons and gamma-rays, a radiation filtering method is adopted. The radiation filter has been designed by using a silicon single crystal cooled by liquid nitrogen and a bismuth crystal. The installation of the main components of the irradiation facility and the irradiation room are finished. Experimental measurements of the neutron beam characteristics have been performed by using bare and cadmium covered gold foils and wires. The in-phantom neutron flux distribution was measured for a flux mapping inside the phantom. The gamma-ray dose was determined by using TLD-700 thermoluminescence dosimeters. The thermal and fast neutron fluxes and the gamma-ray dose were calculated by using the MCNP code, and they were compared with experimental data. The thermal neutron flux and Cd ratio which can be obtained at this facility are 1.49×10 9 n/cm 2 s and 152, respectively. The maximum neutron flux inside the phantom was measured to be 2.79×10 9 n/cm 2 s at a depth of 3 mm in the phantom. The two-dimensional in-phantom neutron flux distribution was determined, and the significant neutron irradiation was observed within 20 mm from the phantom surface. The gamma-ray dose rate for the free beam condition is expected to be about 80 cGy/hr. These experimental results are reasonably well supported by the calculated values of the facility design code. This HANARO thermal neutron facility can be used not only for a clinical trial but also for various basic irradiation researches of the BNCT field.

Boron quantitative analysis and imaging analysis in plants

“…This beam was fitted with single crystal silicon and bismuth crystal filters operated at room temperature to remove fast neutrons and reactor gamma rays. [61] The thermal neutron flux in the irradiation position is 8.8 × 10 8 n•cm -2 •s -1 with a Cd ratio of 132. This beam was used to irradiate samples and SSNTDs.…”