Method and apparatus for probing nuclear material by photofission

• US 9,297,908 B2
• Filed: 06/14/2005
• Issued: 03/29/2016
• Est. Priority Date: 06/21/2004
• Status: Expired due to Fees

• Current Assignee: Commissariat a L'Energie Atomique (French Alternative Energies and Atomic Energy Commission)
• Original Assignee: Commissariat a L'Energie Atomique (French Alternative Energies and Atomic Energy Commission)
• Inventors: Safa, Henri
• Primary Examiner(s): Keith, Jack W
• Assistant Examiner(s): WASIL, DANIEL D
• Application Number:
  US11/570,829
• Publication Number:
  US 20090065693A1
• Time in Patent Office: 3,941 Days
• Field of Search: 376/100, 376/157, 376/190, 376/153, 376/154, 250/310
• US Class Current: 1/1
• CPC Class Codes: G01T 1/167 Measuring radioactive content of objects, e.g. contamination whole body counters G01T1/163
• CPC Class Codes: G01T 3/00 Measuring neutron radiation G01T5/00 takes precedence

Abstract

The invention relates to a method and a system for using photofission to probe an article containing potentially radiation-emitting elements. The article is bombarded by a beam of electrons of sufficient energy, and they are converted into photons by bremsstrahlung directly within the article to be probed, which article is likely to contain photofissile material. No target is added to the package to perform this conversion. Preferably, the article to be probed is a package of radioactive waste, in which the container is made of thick absorbent concrete.

Claims

1. A method of probing an article containing radiation-emitting elements comprised of actinides, comprising:

(a) irradiating an article with an electron beam;

wherein the article comprises;

a peripheral concrete material container made of concrete, and

radioactive waste content located in an interior of the container, wherein the content includes radiation-emitting elements comprising actinides,

wherein the electron beam irradiates the article directly, including the container, without a Bremsstrahlung target being disposed in a path between the electrons of the electron beam and the article,

wherein the irradiating causes electrons from the electron beam to pass through the concrete and into the interior, wherein thickness of the concrete is less than a distance which would have caused the electrons to convert into photons in concrete;

(b) striking a nuclear material with electrons from the electron beam which passed through the concrete in step (a), wherein the striking causes conversion of the electrons into photons;

(c) generating photofission in the actinides with photons produced by the conversion of the electrons in step (b), wherein the photofission causes neutrons to be produced; and

(d) operating at least one neutron detector to measure neutrons produced by the photofission in step (c).

2. A method according to claim 1, wherein, by irradiating the article by means of the electron beam, particles emitted by irradiated portions are detected simultaneously so as to locate the radiation-emitting elements within the article.

3. A method of probing an article containing radiation-emitting elements comprised of actinides, comprising:

(a) irradiating an article with a pulsed electron beam,

wherein the article comprises;

a peripheral concrete material container made of concrete, and

radioactive waste content located in an interior of the container, wherein the content includes radiation-emitting elements comprising actinides,

wherein the electron beam irradiates the article directly, including the container, without a Bremsstrahlung target being disposed in a path between the electrons of the electron beam and the article,

wherein the irradiating causes electrons from the electron beam to pass through the concrete and into the interior, wherein thickness of the concrete is less than a distance which would have caused the electrons to convert into photons in concretes;

(b) striking a nuclear material with electrons from the electron beam which passed through the concrete in step (a), wherein the striking causes conversion of the electrons into photons;

(c) generating photofission in the actinides with photons produced by the conversion of the electrons in step (b), wherein the photofission causes delayed neutrons to be produced after a flash resulting from an electron beam pulse and causes prompt neutrons emitted during the electron beam pulse;

(d) operating at least one neutron detector to measure neutrons produced by the photofission in step (c); and

(e) calculating the ratio of measured prompt neutrons to delayed neutrons so as to determine the isotopic composition of actinides in the radiation-emitting elements.

4. A method of probing an article containing radiation-emitting elements comprised of actinides, comprising:

(a) irradiating an article with a pulsed electron beam,

wherein the article comprises;

a peripheral concrete material container made of concrete, and

radioactive waste content located in an interior of the container, wherein the content includes radiation-emitting elements comprising actinides,

wherein the electron beam irradiates the article directly, including the container,

wherein the irradiating causes electrons from the electron beam to pass through the concrete and into the interior, wherein thickness of the concrete is less than a distance which would have caused the electrons to convert into photons in concrete;

(b) striking a nuclear material with electrons from the electron beam which passed through the concrete in step (a), wherein the striking causes conversion of the electrons into photons;

(c) generating photofission in the actinides with photons produced by the conversion of the electrons in step (b), wherein the photofission causes delayed neutrons to be produced after a flash resulting from an electron beam pulse and causes prompt neutrons emitted during the electron beam pulse;

(d) operating at least one neutron detector to measure neutrons produced by the photofission in step (c); and

(e) calculating the total quantity of actinides in the radiation-emitting elements from the measured prompt neutrons and delayed neutrons.

5. A method according to claim 4, wherein the irradiating is carried out by transporting the electron beam up to the article in a vacuum line.