Slow neutron chemical dosimeter using Cr(VI)—Gd mixture

Patent metadata

Field	Value
Publication number	US-10877166-B1
Application number	US-202016994749-A
Country	US
Kind code	B1
Filing date	Aug 17, 2020
Priority date	Aug 17, 2020
Publication date	Dec 29, 2020
Grant date	Dec 29, 2020

Abstract

Neutron dosimetry is performed using a water-based chemical dosimeter measurement of radiation-induced reduction of hexavalent Cr (VI) to trivalent Cr (III) in the presence of sodium formate at pH 9.2. Neutron absorbance material (Gd-157) increases the neutron interaction with the dosimeter. When a monoenergetic beam with 0.025 eV energy was used as a thermal neutron source 1 mol/dm3 of Gadolinium gave the best outcome while surrounding the dosimeter with 1 cm Gadolinium sheets. The dosimeter was giving acceptable readings when using thermal neutrons.

First claim

We claim:

1. A chemical dosimeter for measuring an absorbed neutron dose, comprising:
a container holding an aqueous solution which includes chromate ions in a hexavalent state (Cr(VI)), gadolinium, and sodium formate, and
one or more gadolinium sheets which surround the aqueous solution,
wherein the one or more gadolinium sheets comprise a window which permits both dosing of the aqueous solution with neutron radiation from an environment outside of the container.

2. The chemical dosimeter of claim 1 , wherein the one or more gadolinium sheets comprises 1 to 5 sheets of gadolinium wherein the sheets have a thickness ranging from 0.1 to 1 cm.

3. The chemical dosimeter of claim 1 , wherein the window has a cross-sectional area of 10 cm×10 cm.

4. The chemical dosimeter of claim 1 , wherein the container holds a volume of 1000 cm 3 .

5. The chemical dosimeter of claim 1 , wherein the one or more gadolinium sheets are external to the container.

6. The chemical dosimeter of claim 1 , wherein the concentration of chromate ions is in the range of 0.001 mol/dm 3 to 0.1 mol/dm 3 .

7. The chemical dosimeter of claim 1 , wherein the concentration of gadolinium dissolved in the aqueous solution is in the range of 0.01 mol/dm 3 to 1 mol/dm 3 .

8. The chemical dosimeter of claim 1 , wherein the concentration of sodium formate dissolved in the aqueous solution is in the range of 0.001 mol/dm 3 to 0.1 mol/dm 3 .

9. The chemical dosimeter of claim 1 , wherein the aqueous solution has a pH of 9.2.

10. The chemical dosimeter of claim 1 , further comprising a plastic or glass housing in which the container is positioned.

11. The chemical dosimeter of claim 10 , wherein the housing forms part of a portable or tabletop device suitable for detecting or monitoring neutron radiation.

12. A method of measuring a dose of neutron radiation, comprising:
exposing an aqueous solution which includes chromate ions in a hexavalent state (Cr(VI)), gadolinium, and sodium formate dissolved in the aqueous solution to neutron radiation;
determining the conversion of chromate ions from the hexavalent state (Cr(VI)) to a trivalent state (Cr(III)) in the aqueous solution based on a spectrophotometric measurement; and
determining the neutron radiation absorbed by the aqueous solution based on the amount of Cr(VI) bleached measured by spectrophotometry.

13. The method of claim 12 , wherein the exposing step is performed through one face of a container that contains the aqueous solution.

14. The method of claim 12 , wherein the determining step is performed by calculating the dose using the formula:
absorbed dose (Gy)=1.04×10 3 ×Δ(OD)

where Δ(OD) is the change in the absorbance at 370 nm of the irradiated Cr—Gd-formate solution.

Assignees

• Univ King Abdulaziz

Inventors

• Elmoujarkach Ezzat
• Djouider Fathi
• Johani Mohammed Al

Classifications

• G01T1/04 Primary

  Chemical dosimeters (G01T1/06, G01T1/08 take precedence) · CPC title

• G01T1/2033

  Selection of materials · CPC title

• G01T3/06

  with scintillation detectors · CPC title

• G01T1/2042

  Composition for liquid scintillation systems · CPC title