Dual neutron flux/temperature measurement sensor

• US 5,352,040 A
• Filed: 04/08/1994
• Issued: 10/04/1994
• Est. Priority Date: 08/24/1992
• Status: Expired due to Fees

• Current Assignee: Martin Marietta Energy Systems, Inc.
• Original Assignee: Martin Marietta Energy Systems, Inc.
• Inventors: Mihalczo, John T., Simpson, Marc L., McElhaney, Stephanie A.
• Primary Examiner(s): Cuchlinski, Jr., William A.
• Assistant Examiner(s): BENNETT, GEORGE B
• Application Number:
  US08/225,363
• Time in Patent Office: 179 Days
• Field of Search: 374/121, 374/130, 374/131, 374/161, 252/301.4 R, 252/301.17, 250/390.11, 376/247, 376/254
• US Class Current: 374/131
• CPC Class Codes: G01K 11/3213 using changes in luminescence, e.g. at the distal end of the fibres
• CPC Class Codes: G01T 3/06 with scintillation detectors

Abstract

Simultaneous measurement of neutron flux and temperature is provided by a single sensor which includes a phosphor mixture having two principal constituents. The first constituent is a neutron sensitive 6LiF and the second is a rare-earth activated Y203 thermophosphor. The mixture is coated on the end of a fiber optic, while the opposite end of the fiber optic is coupled to a light detector. The detected light scintillations are quantified for neutron flux determination, and the decay is measured for temperature determination.

Claims

1. A dual neutron flux/temperature measurement sensor comprising:

a fiber optic having first and second ends;

a coating disposed on the first end of the fiber optic and having a first neutron-sensitive phosphor constituent and a second activated thermophosphor constituent;

neutrons absorbed by the first constituent producing charged particles which cause scintillations to radiate from the second constituent;

light detector means, coupled to the second end of the fiber optic, for converting the scintillations into an electrical signal; and

means, coupled to the light detector means, for correlating a count of the scintillations into a value indicative of neutron flux and at least one characteristic of the scintillations into a value indicative of temperature.

2. A dual neutron flux/temperature measurement sensor according to claim 1, wherein the first constituent is 6LiF and the second constituent is rare-earth activated Y203.

3. A dual neutron flux/temperature measurement sensor according to claim 2, wherein 95% of the Li is 6Li.

4. A dual neutron flux/temperature measurement sensor according to claim 1, wherein the light detector means is a photomultiplier tube, and the signal processing means includes a discriminator-counter and a waveform digitizer, each being coupled to respective displays for indicating neutron flux and temperature, respectively.

5. A dual neutron flux/temperature measurement sensor according to claim 1, wherein the detected light has a lifetime which varies in accordance with variations in ambient temperature at the first end of the fiber optic.

6. A dual neutron flux/temperature measurement sensor according to claim 1, wherein the detected light has an emission spectrum for which the amplitude of the emission peaks varies in accordance with variations in ambient temperature at the first end of the fiber optic.

7. A dual neutron flux/temperature measurement sensor according to claim 1, wherein the light detector means is a photodiode and the signal processing means includes a discriminator-counter and a waveform digitizer, each being coupled to respective displays for indicating neutron flux and temperature, respectively.

8. A dual neutron flux/temperature measurement sensor comprising:

a fiber optic having first and second ends;

a coating disposed on the first end of the fiber optic and having a neutron-sensitive activated thermophosphor constituent;

neutrons absorbed by the coating producing charged particles which cause scintillations to radiate from the thermophosphor constituent;

light detector means, coupled to the second end of the fiber optic, for converting the scintillations into an electrical signal; and

means, coupled to the light detector means, for correlating a count of the scintillations into a value indicative of neutron flux and at least one characteristic of the scintillations into a value indicative of temperature.

9. A dual neutron flux/temperature measurement sensor according to claim 8, wherein the thermophosphor constituent is Y203.

10. A dual neutron flux/temperature measurement sensor according to claim 8, wherein the light detector means is a photomultiplier tube, and the signal processing means includes a discriminator-counter and a waveform digitizer, each being coupled to respective displays for indicating neutron flux and temperature, respectively.

11. A dual neutron flux/temperature measurement sensor according to claim 8, wherein the detected light has a lifetime which varies in accordance with variations in ambient temperature at the first end of the fiber optic.

12. A dual neutron flux/temperature measurement sensor according to claim 8, wherein the detected light has an emission spectrum for which the amplitude of the emission peaks varies in accordance with variations in ambient temperature at the first end of the fiber optic.

13. A dual neutron flux/temperature measurement sensor according to claim 8, wherein the light detector means is a photodiode and the signal processing means includes a discriminator-counter and a waveform digitizer, each being coupled to respective displays for indicating neutron flux and temperature, respectively.