Core assembly and method for increasing irradiation flux of vertical epithermal neutron beams

Abstract

The invention belongs to the technical field of cancericidal nuclide neutron knives and particularly discloses a core assembly and a method for increasing the irradiation flux of vertical epithermal neutron beams. A plurality of fuel rods and depleted uranium rods of a fuel assembly of the core assembly are arranged on the circumference of a plurality of concentric circles at unequal intervals on an upper grid plate and a lower grid plate respectively. The method comprises the following steps: 1, the power of a core is increased, and the arrangement of the fuel rods is determined; 2, a transition section is improved; wherein in the step 1, the power of the core is increased to 45 kw, and the fuel rods are arranged in non-uniform circle distances; improvement of the transition section comprises decreasing of lower beryllium piece thickness to 5 cm, decreasing of water layer thickness to 5 mm and increasing of lower cylinder bottom thickness to 52 mm. The assembly and the method have the advantages as follows: input proportion of the epithermal neutrons can be increased effectively, the output core neutron flux is increased, and the non-uniform coefficient of the core power is reduced.

Description

technical field [0001] The invention belongs to the technical field of neutron capture therapy (BNCT), and in particular relates to a core assembly and a method for improving the irradiation flux of a vertical epithermal neutron beam of an anticancer nuclide neutron knife. Background technique [0002] The nuclear reactor boron neutron capture therapy neutron source can provide neutron beams in two directions, one is the horizontal direction, and the other is the vertical direction. So far, the neutron beams drawn from nuclear reactor neutron sources are almost all horizontal beam devices. The main reason is that there is a large space around the core reflector for setting beam devices, while ensuring a high incident neutron intensity. In order to transmit the prescribed dose to the affected area, BNCT needs the beam to be aimed at the affected area. Under the set beam intensity, the affected area is maintained for a certain irradiation time. According to psychological anal...

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Problems solved by technology

[0005] Even if an irradiation seat is installed under the core of a general reactor, due to the space required for the circulation of the coolant at the bottom of the core and the existence of various complex components, it is difficult to guarantee that the output neutron spectrum is an epithermal neutron spectrum, and there is no one in the world. Vertical epithermal neutron beam with beam intensity meeting requirements

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