US3707631A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Nuclear fuel assay system
Assignee: National Nuclear Corp Ltd
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Filing: 1970-04-02
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Granted: 1972-12-26
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Expires: 1990-04-02
Abstract
Abstract A system for the non-destructive assay of nuclear fuel is disclosed. A scintillating body is positioned near the fissionable fuel species to be assayed. An interrogating beam of low energy neutrons is passed through a moderating material to reduce the neutrons to the thermal or low epi-thermal regions. The moderated interrogating beam penetrates a selected segment of the fuel. Fission of the fissionable species radiates fast neutrons into the scintillating body producing proton recoil in hydrogenous material. These protons produce scintillation events in large sized phosphor grains. Photons from the scintillation events are carried through a transparent light guide to a light detector for counting. The light guide is disclosed as a substantially transparent, non-scintillating polymer surrounded by a light reflecting layer which in turn is covered by a light shield. In a modified form the nuclear fuel to be assayed is positioned in a cavity enclosed by a moderating material with a neutron source and scintillating body radially positioned from the cavity. The scintillating material is arrayed in a series of grooves formed in a transparent light guide connected with a counting device.
Inventors
- 👤 Samuel Untermyer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 10:48
CPC Classifications
G; G01; G01N; G01N23/00; G01N23/02; G01N23/06; G01N23/09; G01T; G01T3/00; G01T3/06; G21; G21C; G21C17/00; G21C17/06; Y; Y02; Y02E; Y02E30/00; Y02E30/30
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
86 words
The invention of claim 1 and further characterized in that the system is adapted to assay an elongated fuel rod containing the nuclear material, the body of scintillating material defines an annulus through which the fuel rod is positioned for assaying a defined segment of the rod in registry with the annulus, and the light guide means comprises a body of non-scintillating, substantially transparent material enclosing the annulus and defined segment of the fuel rod to reflect and transmit said photons to the light detector means.
Claim 2
Dependent Claim
50 words
The invention of claim 2 and further characterized in that the light guide means includes an opaque sleeve coaxially positioned within the annulus and extending through the transparent material to slideably receive the fuel rod, the sleeve shielding the light guide means from external light entering from within the sleeve.
Claim 3
Dependent Claim
39 words
The invention of claim 2 and further characterized in that the light guide means includes reflector means enclosing the transparent material around at least the region surrounding the scintillating material annulus to reflect photons back into the transparent material.
Claim 4
Dependent Claim
51 words
The invention of claim 4 and further characterized in that the moderating means defines a cavity with the light guide means positioned in the cavity spaced from the cavity walls; and, the light reflector means comprises a light reflective layer in the space between the cavity wall and light guide means.
Claim 5
Dependent Claim
29 words
The invention of claim 4 and further including light shield means surrounding the light guide means to exclude external light from the light guide means and light detector means.
Claim 6
Dependent Claim
15 words
The invention of claim 1 and further characterized in that the phosphor comprises zinc sulfide.
Claim 7
Dependent Claim
47 words
The invention of claim 1 and further characterized in that the moderating means encloses the source of neutrons, light detector means, and body of scintillating material, and an opening is provided through the moderating means for positioning the fuel material in the interrogating beam of source neutrons,
Claim 8
Dependent Claim
46 words
The invention of claim 8 and further characterized in that the system includes a casing enclosing the neutron source, light detector means, and light guide means, and the moderating means fills the voids between the casing and neutron source, light detector means, and light guide means.
Claim 9
Dependent Claim
22 words
The invention of claim 1 and furtHer characterized in that the light guide means comprises a non-scintillating, substantially transparent, substantially non-hydrogenous polymer.
Claim 10
Dependent Claim
28 words
The invention of claim 10 wherein the outer surface of the polymer material is polished to provide internal surface reflections of the photons received from the scintillating material.
Claim 11
Dependent Claim
15 words
The invention of claim 10 and further characterized in that the polymer comprises methyl methacrylate.
Claim 12
Dependent Claim
118 words
The invention of claim 1 and further characterized in that the body of scintillating material defines an annulus through which a rod of the nuclear material is positioned for assaying a defined segment of the rod in registry with the annulus, the light guide means comprises a non-scintillating, substantially transparent material enclosing the scintillating material annulus on the periphery of the fuel rod for transmitting photons received from the scintillating material to the light detector means, and including a neutron-absorbing sleeve positioned between the fuel rod and light guide means, the sleeve defining an annular slot in registry with the defined segment of the fuel rod for controlling the neutron flux of the source neutrons entering the rod.
Claim 13
Dependent Claim
120 words
The invention of claim 1 and further characterized in that the moderating means defines a central cavity for receiving bulk or scrap nuclear fuel; the source of neutrons is positioned in the moderating means along a first radius from the cavity; the body of scintillating material is positioned in the moderating means along a second radius from the cavity for receiving fast neutrons radiating from fission events generated by irradiation of the fuel by moderated source neutrons; the light guide means is juxtaposed with the body of scintillating material for receiving photons emitted therefrom; and, the light detector means is juxtaposed with the light guide means for producing counting signals responsive to the photons transmitted through the light guide means.
Claim 14
Dependent Claim
50 words
The invention of claim 14 and further characterized in that the body of scintillating material defines a plurality of spaced-apart, elongated rows arrayed in a plane facing the cavity, and the light guide means comprises a non-scintillating, transparent material extending between the scintillating material rows and the light detector means.
Claim 15
Dependent Claim
33 words
The invention of claim 14 and further characterized in that the neutron source and body of scintillating material are circumferentially spaced around the cavity to interpose a substantial shield of moderating means therebetween.
Claim 16
Independent Claim
175 words
A system for assaying the fissile content in nuclear fuel material, the system comprising the combination of: a body of scintillating material positioned to receive fast neutrons radiating from fission events in the fuel material, the scintillating material comprising a mixture of an hydrogenous material generating recoil protons when struck by the fast neutrons, and phosphor material generating photons when struck by the recoil protons, said phosphor material having grains substantially larger than 5 microns whereby substantially all of the energy of a recoil proton is given up in a single phosphor grain; a source of neutrons having an energy level below approximately 1 MEV and adapted to direct an interrogating beam of said neutrons to the fuel material; moderating means to reduce the energy level of the source neutrons directed toward the fuel to substantially within the thermal or lower epithermal regions; light detector means to detect photons for providing a measurement of said fissile content; and, light guide means to transmit the photons emitted from the scintillating material to the light detector means.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-12-26 | 1976-06-26 | 1976-12-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-12-26 | 1980-06-26 | 1980-12-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-12-26 | 1984-06-26 | 1984-12-26 | $7700.00 | Window Closed / Lapsed |