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Systèmes de mesure safeguard Neutron

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Isotopes of uranium (235U and 238U) do not spontaneously fission at a significant rate like the even-numbered isotopes of plutonium. For this reason, uranium assays utilize an external neutron interrogation source to induce fission in the sample. This is referred to as an active assay. CANBERRA offers a variety of systems to perform neutron assay for safeguards applications.

JCC-12 Inventory Sample Neutron Coincidence Counter (INVS)

JCC-12 Inventory Sample Neutron Coincidence Counter (INVS)

Description

The JCC-12 is based on a design developed at Los Alamos National Laboratories (LANL) in the United States under the United States Department of Energy development programs. The JCC-12 has also been authorized by the International Atomic Energy Agency (IAEA) in Vienna, Austria, for routine inspection use of nuclear material at facilities placed under international safeguards under agreements established by the Non-Proliferation Treaty and Information Circular (INFCIRC) 153 (Revised). The JCC-12 was specifically developed to meet IAEA safeguards requirements for the INVS, the Inventory Sample Coincidence Counter by LANL.

The JCC-12 assays plutonium inventory samples by counting coincidence neutrons from the spontaneous fission of the even numbered isotopes of plutonium. The cylindrical-shaped sample holder accommodates various samples including liquids, powders and pellets. The sample cavity can be enlarged to 8.8 cm in diameter by removing the polyethylene sleeve around the aluminum sample carrier. However, enlarging the sample cavity decreases counter efficiency. The counter is intended to operate in the 0.1 to 500 g Pu mass range.

A cadmium sleeve lines the central region of the sample cavity to flatten the response profile along the length of the 3He tubes. Surrounding the sample cavity is a ring of high-density polyethylene with a total of sixteen 3He proportional detectors embedded in the polyethylene. The tubes are arranged in two concentric rings to maximize detector efficiency. The tubes are divided into four groups of four, each group is wired together and connected to one JAB-01 Preamplifier/Amplifier/Discriminator circuit board. The four JAB-01s are mounted inside a sealed junction box. LED indicator lights are mounted externally on the junction box to indicate proper operation of each JAB-01 channel. Electrical connections between the JCC-12 and the JSR-12 Neutron Coincidence Analyzer include +5 V and HV. The combination of signals will be combined into a logical OR.

The detector is highly portable and fits into an optional carrying case for transport.

A JSR-12 Neutron Coincidence Analyzer, a computer and analysis software are required for coincidence counting but are not included as part of the JCC-12.

JCC-12 Inventory Sample Neutron Coincidence Counter (INVS)

Features

  • Authorized for routine inspection use by the International Atomic Energy Agency (IAEA) as the INVS, the Inventory Sample Coincidence Counter
  • Designed for passive neutron coincidence assay of plutonium
  • High counting efficiency - 35%
  • Variable sample cavity size
  • Fast Amptek® Electronics
  • Sixteen 3He detectors
  • Portable
  • Optional transport container
JCC-13/JCC-14 Sample Inventory Coincidence Counters

JCC-13/JCC-14 Sample Inventory Coincidence Counters

Description

The JCC-13 and JCC-14 are based on a design developed at Los Alamos National Laboratories (LANL) in the United States under the United States Department of Energy development programs. They have also been authorized for routine inspection use of nuclear material at facilities placed under international safeguards.

The JCC-14 is designed to assay plutonium inventory samples inside a glovebox. It is an upgraded version of the JCC-12, and fits around the drywell of the glovebox. Samples are loaded into an aluminum carrier inside the glovebox and then lowered into the JCC-14 for counting. The JCC-13 which is a modification of the Los Alamos National Laboratory design, differs only in the sample diameter and the method of sample loading. The JCC-13 is slightly larger in diameter than the JCC-14, and uses top loading to minimize torn sample bags. The JCC-13 is a transportable counter, designed for verification inspections at multiple sites.

The JCC-13 and JCC-14 provide a flatter axial response and higher efficiency than the JCC-12. The cylindrical-shaped sample holder accommodates various samples including liquids, powders and pellets.

The sample cavity can be enlarged by removing the polyethylene sleeve around the aluminum sample carrier.

However, enlarging the sample cavity decreases efficiency and makes the measurement more sensitive to hydrogen in the sample. The counter is intended to operate in the 0.1 to 500 g Pu mass range.

A cadmium sleeve lines the central region of the sample cavity to flatten the response profile along the length of the 3He tubes. The graphite end plugs act as reflectors. Surrounding the sample cavity is a ring of high-density polyethylene with 18 3He proportional detectors embedded in the polyethylene.

The tubes are arranged in two concentric rings to maximize detector efficiency. The tubes are divided into three groups of six. Each group is wired together and connected to one JAB-01 Amplifier/Discriminator circuit board. The three JAB-01s are mounted inside the high voltage junction box with LED indicator lights mounted externally on the junction box to indicate proper operation of each JAB-01 channel. Electrical connections between the JCC-13 or JCC-14 and the JSR-12 Neutron Coincidence Analyzer include +5 V and HV. The combination of signals will be combined into a logical OR.

The detector is portable and fits into an optional carrying case for transport.

A JSR-12 Neutron Coincidence Analyzer, a computer and analysis software are required for coincidence counting but are not included with the JCC-13 or JCC-14.

JCC-13/JCC-14 Sample Inventory Coincidence Counters

Features

  • Authorized for routine inspection use as the INVS, Inventory Sample Coincidence Counter
  • Designed for passive neutron assay of plutonium
  • High counting efficiency - 42%
  • Variable sample cavity size
  • Fast Amptek® electronics
  • 18 3He detectors
  • Transportable
  • Optional transport container
JCC-31 High Level Neutron Coincidence Counter

JCC-31 High Level Neutron Coincidence Counter

Description

The JCC-31, which is based on a technology transfer from Los Alamos National Laboratory, measures the 240Pu-effective mass in a sample by detecting coincidence neutrons from the spontaneous fission of plutonium. The effective mass of 240Pu is the mass of 240Pu which would emit the same number of spontaneous fission neutrons per second as the combined 238Pu, 240Pu and 242Pu in the sample.

The detector can measure up to several kilograms of plutonium.

The JCC-31 has a cylindrical-shaped sample cavity 41 cm high by 17 cm in diameter. It is intended to assay plutonium samples including PuO2, mixed oxides (PuO2-UO2), metal carbides, fuel rods, fast critical assemblies, solution, scrap, and waste. A cadmium sleeve surrounds the sample cavity to prevent the re-entry of thermalized neutrons into the sample, which could induce fission in the sample and adversely affect the results. Outside the cadmium sleeve is a ring of high-density polyethylene with eighteen 3He tubes placed in the polyethylene.

The tubes are arranged in a single ring around the sample with optimum spacing between the tubes for maximum counter efficiency for a transportable counter. The tubes are divided into six groups of three with each group wired together and connected to one JAB-01 Amplifier/Discriminator circuit board. The six JAB-01s are mounted inside a sealed junction box. LED indicator lights are placed externally on the junction box to indicate proper operation of each JAB-01 channel. Electrical connections between the JCC-31 and the JSR-12 include +5 V and HV. The combination of signals will be combined into a logical OR.

A cadmium sleeve wrapped around the outside of the JCC-31 provides radiation protection for personnel as well as background reduction.

A JSR-12 Neutron Coincidence Analyzer, a computer and analysis software are required for coincidence counting but are not included with the JCC-31.

JCC-31 High Level Neutron Coincidence Counter

Features

  • Designed for passive neutron coincidence assay of plutonium
  • Eighteen 3He detectors
  • Fast Amptek® electronics
  • Transportable for inspections at multiple sites
  • Optional transport container
JCC-51 Active Well Neutron Coincidence Counter

JCC-51 Active Well Neutron Coincidence Counter

Description

Isotopes of uranium (235U and 238U) do not spontaneously fission at a significant rate like the even-numbered isotopes of plutonium. For this reason, uranium assays utilize an external neutron interrogation source to induce fission in the sample. This is referred to as an active assay.

The JCC-51, which is based on a technology transfer from Los Alamos National Laboratory, is used to make active neutron measurements on items such as bulk UO2 samples, high-enrichment uranium metals, UAl alloy scraps, LWR fuel pellets and 238UTh fuel materials. Americium-Lithium (AmLi) neutron sources (one in the top plug and one in the bottom plug) induce fission in the uranium sample and the coincidence neutrons are counted. If the AmLi sources are removed, the counter can be operated in a passive mode to assay plutonium.

Forty-two 3He tubes are embedded in the high-density polyethylene surrounding the sample well. They are arranged in two concentric rings to maximize efficiency. The tubes are divided into six groups of seven, and each group is wired together and connected to one JAB-01 Amplifier/Discriminator circuit board. The six JAB-01s are mounted inside a sealed junction box, with LED indicators placed externally on the junction box to indicate proper operation of each JAB-01 channel.

Electrical connections between the JCC-51 and the JSR-12 Neutron Coincidence Analyzer include +5 V and HV. The combination of signals will be combined into a logical OR.

The sample well height can be increased by removing one or both of the polyethylene discs in the top and bottom plugs. Enlarging the sample well will increase the absolute efficiency because the ends of the 3He tubes are not as shielded, but decrease the precision because the random background from the AmLi source is increased.

A cadmium sleeve is wrapped around the outside of the counter to reduce the background and to reduce personnel exposure.

The counter can be operated in two active modes: thermal mode and fast mode. Thermal mode is used for low-enrichment material such as UO2 pellets, U3O8 powder and low content scrap (<50 g 235U), high-enrichment material including 235UTh and 233UTh (HTGR fuels) and samples with large quantities of hydrogenous materials such as scrap with plastic bags, uranyl nitrate (few g/L to few hundred g/L) and plutonium solutions (few g/L to few hundred g/L). The fast mode is used for high-enrichment uranium metal.

For thermal mode, the internal cadmium sleeve and cadmium in the end plugs are removed.

For assay of large samples such as fuel rods or plates, the counter is turned on its side, the end plugs are removed and an MTR Insert (JWI-11) is positioned inside the counter. The cart is used to support the counter in the horizontal position.

The counter sits on a cart that is designed so that one person can move the unit.

Two AmLi neutron sources (JNS-01), JSR-12 Neutron Coincidence Analyzer, a computer and analysis software are required for neutron coincidence counting but are not included with the JCC-51.

JCC-51 Active Well Neutron Coincidence Counter

Features

  • Designed for active neutron interrogation of uranium
  • Variable sample cavity size
  • Fast Amptek® electronics
  • 42 3He detectors
  • Passive counting of plutonium when the AmLi sources are removed
  • Optional transport containers
JCC-61/JCC-62 Universal Fast Breeder Reactor Subassembly Counters

JCC-61/JCC-62 Universal Fast Breeder Reactor Subassembly Counters

Description

The JCC-61 and JCC-62 are based on a design developed at Los Alamos National Laboratories (LANL) for the United States Department of Energy. They have also been authorized by the International Atomic Energy Agency (IAEA) in Vienna, Austria, for routine inspection use of nuclear material at facilities placed under international safeguards.

The JCC-61 and JCC-62 quantitatively measure fast breeder fuel sub-assemblies, individual fuel pins, or a group of fuel pins. They count coincidence neutrons from the spontaneous fission of the even numbered isotopes of plutonium. Subassemblies can be lowered through the top of the counter using a crane. If this is not possible, the door opens to allow side entry. For ease in moving, the door can be removed.

Twelve 3He tubes are surrounded by a polyethylene and cadmium sleeve in the central region to flatten the axial response and decrease counter die-away time. The cadmium stops 15 cm (5.9 in.) from the bottom and 17.5 cm (6.9 in.) from the top to compensate for end leakage. The counter is undermoderated to minimize weight and to maximize the amount of plutonium that can be measured. The cadmium liner inside the sample cavity prevents reentry of thermal neutrons which could induce fission in the fuel and adversely affect the measurement.

The JCC-62 has an enlarged sample diameter to allow measurement of Super Phenix fuel subassemblies. To compensate for larger end effects, polyethylene collars were added to the ends of the counter.

The 3He tubes in the JCC-61 and JCC-62 are arranged in a single ring, and are divided into six groups of two. Each group is wired together and connected to one JAB-01 Amplifier/Discriminator circuit board. The six JAB-01s are mounted inside a high voltage junction box. LED indicator lights are placed externally to the junction box to indicate the proper operation of each JAB-01 channel. Electrical connections between the JCC-61 or JCC-62 and the JSR-12 include +5 V and HV. The combination of signals will be combined into a logical OR.

A JSR-12 Neutron Coincidence Analyzer, a computer and analysis software are required for coincidence counting but are not included with the JCC-61 or JCC-62.

JCC-61/JCC-62 Universal Fast Breeder Reactor Subassembly Counters

Features

  • Authorized for routine inspection use by the International Atomic Energy Agency (IAEA) as the Universal Fast Breeder Counter (UFBC)
  • Designed for passive neutron measurement of plutonium in fast breeder reactor fuel subassemblies
  • Fast Amptek® electronics
  • Twelve 3He detectors
  • Transportable
JCC-71/JCC-72/JCC-73 Neutron Coincidence Collars

JCC-71/JCC-72/JCC-73 Neutron Coincidence Collars

Description

The Model JCC-71 Neutron Coincidence Collar is a passive/active neutron counter for the measurement of the 235U content per unit length in fresh PWR, BWR and CANDU fuel assemblies. The JCC-71 can also be used to measure the plutonium content of MOX fuel. The system design is based on technology transfer from the Los Alamos National Laboratory.

The JCC-71 is made up of four counter banks, each composed of high-density polyethylene for the moderation of the fission neutrons. Each bank contains several 3He detectors for the detection of neutrons. The counter can operate in both an active mode and a passive mode. For the passive mode, all four counter banks are used around the fuel assembly. If operated in the active mode, one bank of detectors is replaced with a polyethylene bank containing only an Americium-Lithium (AmLi) interrogating source. (The AmLi source must be ordered separately.)

In the active mode, the AmLi source is required to interrogate the fuel, and coincidence counting of the induced fission neutrons from 235U is performed. The AmLi source is contained in a tungsten source bottle and placed inside the polyethylene bank. The AmLi neutrons are thermalized in the polyethylene and induce fission in the 235U. The average energy from the induced fission is higher than the moderated AmLi neutrons and gives fast neutron multiplication which allows the measurement to penetrate into the interior of the fuel assemblies. For HEU fuel, cadmium liners can be added to improve neutron penetrability.

JCC-71/JCC-72/JCC-73 Neutron Coincidence Collars

Features

  • Designed for neutron coincidence measurement of uranium in PWR, BWR and CANDU fuel assemblies, or plutonium in MOX fuel assemblies
  • Variable sample cavity size (Model JCC-71)
  • Fast Amptek® electronics
  • 3He detectors
  • Transportable
  • Optional transport container
  • Authorized for routine inspection use by the International Atomic Energy Agency (IAEA) as the Uranium Neutron Collar (UNCL and UNCL II)
PSMC-01 – Plutonium Scrap Multiplicity Counter

PSMC-01 – Plutonium Scrap Multiplicity Counter

Description

The Plutonium Scrap Multiplicity Counter (PSMC) is a high efficiency neutron coincidence counter designed for measuring the multiplicity of the neutron emission from both spontaneous fission and induced-fission reaction in plutonium and uranium. The PSMC was originally developed by Los Alamos National Laboratory to measure impure plutonium and mixed-oxide (MOX) scrap materials for safeguards and inventory control applications. Intended for the measurement of items up to 10 liters in volume, the counter is designed to provide improved measurement precision through the use of multiple rings of 3He proportional tubes.

Neutron Detection

The counter provides a neutron detection efficiency of >50% for 240Pu spontaneous fission neutron emitted within the center of the assay cavity. The high neutron efficiency makes the PSMC an ideal counter for the assay of plutonium product, waste or scrap material. For clean or slightly impure product materials, measurement precisions of less than 1% are readily achievable in multiplicity mode over the mass range of 1 g to several kilograms of plutonium oxide and MOX.

System Configuration

The PSMC system configuration requires minimal setup time consisting only of the neutron counter, multiplicity shift register and personal computer loaded with operating software.

The fully computer controlled shift register provides both neutron coincidence and multiplicity capability that is selectable. This provides the user with analysis capability for a broad range of material configurations including: Pu pellets, powder, solutions, Mixed Oxides, MOX fuel pellets, Pu fuel assemblies, HEU and LEU in metals, oxides, powders, fuel pellets and rods, as well as uranium hexaflouride (UF6) samples.

The multiplicity shift register, software, and personal computer are supplied separately.

Key Benefits

  • Provides high accuracies for plutonium product, waste, or scrap materials
  • Fully integrated system requires minimal setup and training
  • Applicable to a wide range of sample types

PSMC - Pu Scrap Multiplicity Counter

Applications

  • Waste and Safeguards measurements for plutonium contents

Features

  • High efficiency: >50% for 240Pu spontaneous fission neutrons
  • Die-away time: 50 µs
  • Uniform axial response profile
  • Sample Cavity 19.7 x 41 cm (7.8 x 16.1 in.) (Dia. x Height)
  • Custom pre-amplifier electronics for fast-processing and low-noise
  • Operated using CANBERRA JSR-14 and JSR-15 shift registers
  • Includes internal de-randomizing board
  • Available with NDA 2000 software
  • Higher efficiency versions available (greater than 60%)
LEMC - Large Epi-Thermal Multiplicity Counter

LEMC - Large Epi-Thermal Multiplicity Counter

Description

The Large Epi-Thermal Multiplicity Counter (LEMC) is a high performance neutron coincidence counter designed for measuring the multiplicity of the neutron emission from both spontaneous fission and induced-fission reaction in plutonium and uranium. The LEMC was developed to measure impure plutonium and mixedoxide (MOX) scrap materials for safeguards and inventory control applications. Intended for the measurement of items up to 40 liters (10 gallons) in volume, the counter is designed to provide improved measurement precision through the use of multiple cadmium layers and high pressure (10 atm) 3He proportional tubes.

Features

  • Designed for quantitative passive neutron analysis
  • High Efficiency: >50% for 240Pu spontaneous fission neutrons
  • Fast Die-Away Time: 24 μs
  • Improved measurement precision
  • Large Sample Cavity accommodates samples
    up to 40 L
  • Fast Amptek electronics
  • Low deadtime: 41 ns
  • Internal De-randomizing Board
  • Operated using JSR-14 shift registers
  • Available with NDA 2000 software

LEMC - Large Epi-Thermal Multiplicity Counter