Nuclear reactor ex-core startup neutron detector

Claim 2

An Ex-core Startup Neutron Detector for a nuclear reactor comprising: a. a photomultiplier tube having a radiation darkening resistant end window at an input end and an electrical connector at an output end; b. a thermal neutron responsive scintillator medium in optical communication with said photomultiplier tube at said input end; c. a neutron thermalizer adjacent to said scintillator medium whereby neutrons incident upon said neutron thermalizer are thermalized prior to passing into said scintillator medium; and d. radiation shielding at least partially surrounding said photomultiplier tube.

Claim 3

The neutron detector of claim 1, wherein said radiation shielding includes a neutron absorber adjacent to at least a portion of said photomultiplier tube away from said input end for shielding said photomultiplier tube from neutrons.

Claim 4

The neutron detector of claim 1, wherein said radiation shielding includes a shielding which envelopes said photomultiplier tube and which is opaque to gamma radiations.

Claim 5

The neutron detector as recited in claim 3, wherein said enveloping shield comprises lead.

Claim 6

The neutron detector as recited in claim 1, wherein said neutron thermalizer includes silicone resin.

Claim 7

The neutron detector as recited in claim 1, wherein said scintillator medium includes a cerium-doped lithium silicate scintillation crystal.

Claim 8

The neutron detector as recited in claim 2, wherein said neutron absorber includes borated silicone resin.

Claim 9

The neutron detector as recited in claim 3, wherein said neutron thermalizer includes silicone resin.

Claim 10

The neutron detector as recited in claim 3, further comprising a neutron absorber adjacent to at least a portion of said photomultiplier tube away from said input end for shielding said photomultiplier tube from neutrons.

Claim 11

The neutron detector as recited in claim 9, wherein said neutron absorber includes borated silicone resin.

Claim 12

The neutron detector as recited in claim 1, wherein said photomultiplier tube is a nuclear radiation insensitive photomultiplier tube.

Claim 13

The neutron detector as recited in claim 11, wherein said radiation darkening resistant end window of said photomultiplier input end includes a faceplate consisting of optical grade purified fused silica.

Claim 14

The neutron detector as recited in claim 7, wherein said borated silicone resin includes a boron carbide-silicone resin mixture.

Claim 15

The neutron detector as recited in claim 5, wherein said neutron thermalizer includes a fiberglass-silicone resin mixture.

Claim 16

The neutron detector as recited in claim 6, wherein said neutron thermalizer is a silicone resin.

Claim 17

The neutron detector as recited in claim 6, wherein said radiation shielding includes a neutron absorber adjacent to at least a portion of said photomultiplier tube away from said input end for shielding said photomultiplier tube from neutrons.

Claim 18

The neutron detector as recited in claim 6, wherein said radiation shielding includes a shielding which envelopes said photomultiplier tube and which is opaque to gamma radiations.

Claim 19

The neutron detector as recited in claim 1, wherein said scintillator medium includes a cerium-doped lithium silicate scintillation crystal.

Claim 20

The neutron detector as recited in claim 9, wherein said scintillator medium includes a cerium-doped lithium silicate scintillation crystal.

Claim 21

An ex-core start up neutron detector for use in a nuclear reactor environment comprising: a. a closed lead housing opaque to gamma radiation; b. a nuclear radiation insensitive photomultiplier tube encased within said housing, said photomultiplier tube having an electrical connector at an output end and a radiation darkening resistant end window at an input end including a faceplate consisting of optical grade purified fused silica; c. a cerium-doped lithium silicate scintillation crystal within said housing responsive to thermalized neutrons in optical communication with said photomultiplier tube to said input end; d. a silicone resin neutron thermalizer within said housing adjacent to said scintillation crystal whereby neutrons incident on said silicone resin are thermalized prior to passing into said scintillation crystal; and e. a borated silicone resin neutron absorber adjacent to at least a portion of said photomultiplier tube away from said input end for shielding said photomultiplier tube from neutrons.

Claim 22

An ex-core start up neutron detector for use in a nuclear reactor environment comprising: a. a closed lead housing opaque to gamma radiation; b. a nuclear radiation insensitive photomultiplier tube encased within said housing, said photomultiplier tube having an electrical connector at an output end and a radiation darkening resistant end window at an input end including a faceplate consisting of optical grade purified fused silica; c. a cerium-doped lithium silicate scintillation crystal within said housing responsive to thermalized neutrons in optical communication with said photomultiplier tube to said input end; d. a silicone resin neutron thermalizer within said housing adjacent to said scintillation crystal whereby neutrons incident on said silicone resin are thermalized prior to passing into said scintillation crystal; and e. a borated silicone resin neutron absorber adjacent to at least a portion of said photomultiplier tube away from said input end for shielding said photomultiplier tube from neutrons.