Neutron control device and neutron irradiation apparatus

Patent metadata

Field	Value
Publication number	US-9675816-B2
Application number	US-201414914256-A
Country	US
Kind code	B2
Filing date	Sep 5, 2014
Priority date	Sep 6, 2013
Publication date	Jun 13, 2017
Grant date	Jun 13, 2017

Abstract

The neutron irradiation apparatus includes an introduction tube for introducing a proton beam, a target structure provided in a lower end of the introduction tube, an aluminum fluoride layer disposed below the target structure in an irradiation path of neutrons generated in the target structure, and a heavy water layer placed under the aluminum fluoride layer in layers. The aluminum fluoride layer is set at a thickness that increases epithermal neutrons. Since use of only the aluminum fluoride layer increases its thickness too much, heavy water is placed. Heavy water moderates neutrons quickly, and allows increasing epithermal neutrons without increasing the thickness. The combination of the aluminum fluoride layer and the heavy water layer allows increasing epithermal neutrons by attenuating only fast neutrons without increasing thermal neutrons. Accordingly, neutron flux with many epithermal neutrons is obtained.

First claim

The invention claimed is:

1. A neutron control device comprising:
a fluoride layer containing aluminum fluoride, magnesium fluoride, or Fluental, the fluoride layer being a first moderation layer; and
a heavy water layer containing deuterium, the heavy water layer being a second moderation layer disposed below the first moderation layer, wherein
the fluoride layer and the heavy water layer are stacked each other in an irradiation path of neutrons generated in a target irradiated with a proton beam.

2. The neutron control device according to claim 1 , further comprising a plate-shaped first neutron absorber made of cadmium downstream of the heavy water layer.

3. The neutron control device according to claim 1 , further comprising a lead plate disposed downstream of a first neutron absorber.

4. The neutron control device according to claim 1 , further comprising a plate-shaped second neutron absorber containing boron or lithium provided around a first neutron absorber.

5. A neutron irradiation apparatus comprising:
a proton beam introduction tube for introducing a proton beam;
a target provided at a distal end of the proton beam introduction tube;
a graphite body disposed around the target;
the neutron control device according to claim 1 ; and
a neutron moderation tank disposed to surround the graphite body and the neutron control device, into which tank a boric acid solution or another neutron moderator is introduced, wherein
the neutron control device is disposed below the target.

Assignees

• Mitsubishi Heavy Ind Mechatronics Systems Ltd
• Univ Osaka

Inventors

• Kuri Shuhei
• Takahashi Toshiharu
• Horiike Hiroshi
• Hoashi Eiji
• Murata Isao
• Doi Sachiko
• Kato Itsuro

Classifications

• H05H6/00

  Targets for producing nuclear reactions (supports for targets or objects to be irradiated G21K5/08 {; preparation of tritium C01B4/00; targets, e.g. pellets for fusion reactions by laser or charged particles beam injection H05H1/22}) · CPC title

• A61N2005/109

  Neutrons · CPC title

• H05H3/06 Primary

  Generating neutron beams (targets for producing nuclear reactions H05H6/00; neutron sources G21G4/02) · CPC title

• A61N5/1077

  Beam delivery systems · CPC title

• G21K5/04

  with beam-forming means · CPC title