Radiation monitor

Patent metadata

Field	Value
Publication number	US-11231507-B2
Application number	US-201917059535-A
Country	US
Kind code	B2
Filing date	May 16, 2019
Priority date	Jun 15, 2018
Publication date	Jan 25, 2022
Grant date	Jan 25, 2022

Abstract

A screw compressor includes a screw rotor, a casing, and a fluid supply portion to supply fluid in a membrane form into a compression chamber in the casing. The screw rotor has a male and female rotors. A male bore covering the male rotor and a female bore covering the female rotor are formed on the inner surface of the casing. An intersection line, on a higher pressure side, of the male and female bores is defined as a compression cusp. In a bore development view, a trajectory made by the first intersection of an extension line of a female lobe ridge and a male lobe ridge being moved, along with the rotation of the male and female rotors, is defined as a trajectory line. An opening of the fluid supply section to the compression chamber is positioned between the compression cusp and the trajectory line.

First claim

What is claimed is:

1. A radiation monitor comprising:
a radiation detecting unit including a phosphor that emits light responsive to incident radiation;
an optical fiber that transmits the light emitted from the phosphor of the radiation detecting unit;
a photodetector that converts single photons, the single photons making up the light transmitted from the optical fiber, to electrical pulse signals;
a counter that counts the electrical pulse signals converted by the photodetector;
a database configured to associate counting rates of electrical pulse signals with dose rates of radiation; and
an arithmetic section configured to convert a counting rate of electrical pulse signals, the counting rate having been counted by the counter, to a dose rate of radiation by using the database, wherein
the phosphor contains an additive that emits photons when energy is applied, and
the additive has a concentric concentration gradient.

2. The radiation monitor according to claim 1 , wherein
the phosphor has a spherical shape.

3. The radiation monitor according to claim 1 , wherein
the phosphor has a hemispherical shape.

4. The radiation monitor according to claim 1 , wherein
the phosphor has a cylindrical shape.

5. The radiation monitor according to claim 1 , wherein
the phosphor has a prismatic shape.

6. The radiation monitor according to claim 1 , wherein
the additive has the concentric concentration gradient in which concentration decreases outwards from a central portion of the phosphor.

7. The radiation monitor according to claim 1 , wherein
the additive has the concentric concentration gradient in which concentration increases outwards from a central portion of the phosphor.

8. The radiation monitor according to claim 1 , further comprising:
an optical filter that attenuates the light transmitted from the optical fiber, wherein
the optical filter is interposed between the optical filter and the photodetector.

9. The radiation monitor according to claim 1 , further comprising:
at least one radiation detecting unit; and
at least one optical fiber, whereby the radiation monitor includes at least a first optical fiber and a second optical fiber, wherein
the arithmetic section is configured to convert to dose rates of radiation to a plurality of different positions.

10. The radiation monitor according to claim 9 , further comprising:
a light selecting device configured to select, as the light from which the photodetector is to acquire the electrical pulse signals, one of light transmitted from the first optical fiber and light transmitted from the second optical fiber, and
a control section configured to control the light selecting device.

11. The radiation monitor according to claim 10 , further comprising:
an optical filter that attenuates the light, wherein
the optical filter is interposed between the light selecting device and the photodetector.

12. The radiation monitor according to claim 10 , further comprising:
a plurality of optical filters, including at least a first optical filter and a second optical filter, to attenuate light, wherein
the first optical filter is interposed between the first optical fiber and the light selecting device, and
the second optical filter is interposed between the second optical fiber and the light selecting device.

13. A radiation monitor comprising:
a radiation detecting unit including a phosphor that emits light responsive to incident radiation;
an optical fiber that transmits the light emitted from the phosphor of the radiation detecting unit;
a photodetector that converts single photons, the single photons making up the light transmitted from the optical fiber, to electrical pulse signals;
a counter that counts the electrical pulse signals converted by the photodetector;
a database configured to associate counting rates of electrical pulse signals with dose rates of radiation; and
an arithmetic section configured to convert a counting rate of electrical pulse signals, which has been counted by the counter, to a dose rate of radiation by using the database, wherein
the phosphor has a multilayer structure in which a characteristic of an additive differs in respective layers,
the phosphor contains an additive that emits photons when energy is applied, and
the additive has a concentric concentration gradient.

14. The radiation monitor according to claim 13 , wherein
the characteristic of the additive is an element species of the additive.

15. The radiation monitor according to claim 13 , wherein
the characteristic of the additive is a concentration of the additive.

16. The radiation monitor according to claim 13 , wherein
the characteristic of the additive is a density distribution of the additive.

Assignees

• Hitachi Ltd

Inventors

• Hatakeyama Shuichi
• Tadokoro Takahiro
• Ueno Yuichiro
• Nagumo Yasushi
• Ueno Katsunori
• Okada Kouichi

Classifications

• Y02E30/30

  Nuclear fission reactors · CPC title

• G01T1/17

  Circuit arrangements not adapted to a particular type of detector {(pulse-selection circuits H03K, G01R)} · CPC title

• G01T1/023 Primary

  Scintillation dose-rate meters · CPC title

• G01T1/2006

  using a combination of a scintillator and photodetector which measures the means radiation intensity · CPC title

• G01T1/10 Primary

  Luminescent dosimeters · CPC title