Systèmes Neutron de mesures de déchets
Produits dans cette famille
CANBERRA offers various. neutron assay, systems to measure containers ranging from non-packaged waste to vehicles.
WM3500 Curved Passive Neutron Slab Counters
The curved slab neutron coincidence slab counter measures the plutonium content of the sample by detecting coincidence neutrons from the spontaneous fission of the even numbered isotopes of plutonium. The counter is designed to make either quantitative or go/no-go measurements. A JSR-12 or JSR-14 Neutron Coincidence Analyzer is required for coincidence counting (ordered separately).
The counter is comprised of four separate slab counters. These counters are curved through 90° and may be fitted together to form a passive well counter. Each section of the counter contains eight 91 cm (35.8 in.) 3He proportional tubes forming a single detector bank. The output from each of these detector banks is daisy chained, providing a single TTL signal out to the shift register. When configured in its smallest sample geometry (i.e. the four slabs are in contact) the WM3500 provides an overall efficiency of 19.4%. As the sections are positioned further apart, the efficiency decreases. The full counter has a height of 114 cm (44.9 in.) and forms a circle with inner diameter of 54 cm (21.3 in.) and has an outer diameter of approximately 86 cm (33.9 in.). For the most accurate results the sample should be placed on a pedestal to center it vertically within the counter. Since this counter does not have end plugs, the axial response will fall quickly as the source is moved near the ends of the counter.
- Designed for quantitative passive neutron analysis
- Suitable for go/no-go measurement of plutonium
- Flexibility geometry for assay of pails, drums or large objects
- Expandable - additional slabs can be connected to improve performance with large samples
- Fast Amptek electronics
- High efficiency >19%
- Sensitivity - detection levels of <50 mg W.G. Pu
- All HDPE moderator enclosed in stainless steel skins
- Free standing detector assemblies
- Operated using JSR-12 or JSR-14 shift registers
- Available with NDA 2000 software
JCC-41 Flat-Squared Neutron Coincidence Counter
The JCC-41, which is based on Monte Carlo design calculations performed at Los Alamos National Laboratory, measures the effective 240Pu mass in a sample by detecting coincidence neutrons from the spontaneous fission of the even numbered isotopes of plutonium. The JCC-41 is designed for in-plant measurements of large plutonium samples (up to several kg Pu), but can be used for plutonium waste samples with milligram quantities of plutonium. The JCC-41 has a higher efficiency, larger sample size and flatter axial response than the transportable JCC-31. The system consists of a JCC-41 counter head and sample hoist mechanism.
The JCC-41 has a cylindrical-shaped sample cavity. 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 reentry of thermalized neutrons into the sample, which could induce fission in the sample and adversely affect the results.
Outside the cadmium sleeve is a polyethylene/cadmium liner to flatten the axial response. Twenty-four 3He tubes are embedded in the high-density polyethylene. The tubes are arranged in a single ring around the sample with optimum spacing between the tubes for maximum counter efficiency.
The tubes are divided into six groups of four with each group wired together and connected to one of the six JAB-01 Amplifier/Discriminator circuit boards which are mounted inside a high voltage 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-41 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-41 provides radiation protection for personnel as well as background reduction.
The external polyethylene shielding and special design (graphite end plugs and polyethylene/cadmium liner) give uniform response axially over the sample cavity, making the counter relatively insensitive to matrix effects.
A JSR-12 Neutron Coincidence Analyzer, a computer and analysis software are required for coincidence counting but are not included with the JCC-41.
- Well-type neutron coincidence counter for in-plant applications
- Special design features give uniform spatial response axially over the sample cavity
- Relatively insensitive to sample matrix effects
- Relatively flat neutron energy response
- Twenty-four 3He Detectors
- Fast Amptek® electronics
- Large (61 x 24 cm) sample cavity
- Exterior neutron shielding
- Unit's high efficiency (>22%) provides high counting rates and good precision
- Response is better than 28 counts/sec per gram 240Pu(a 1000 second counting time gives a precision of 2.4% for 0.06 gram 240Pu)
WM3100 High Efficiency Passive Neutron Counter (HENC)
The High Efficiency Neutron Counter (HENC) represents the ultimate in CANBERRA's family of passive neutron coincidence counters. Combining a detection efficiency of over 30% with increased shielding to reduce backgrounds, the HENC is designed to assay 208 liter (55 gallon) drums to detection levels on the order of 1.6 mg of 240Pu-effective in a 1000 second count time. With the addition of enhanced correction and analysis techniques such as Add-A-Source and multiplicity counting the HENC is also an extremely accurate assay system.
Components of the proposed system include the neutron counter with 3He detectors, Amptek-based fast preamplifier/discriminator circuit boards (Model JAB-01), coincidence electronics, computer hardware, and application software. The turnkey system is designed for ease of operation and minimal maintenance.
Spontaneous fission neutrons from the even isotopes of plutonium will be measured using passive neutron coincidence or multiplicity counting techniques. The neutron counter consists of a high-density polyethylene (HDPE) moderator with 3He tubes embedded in the HDPE on all six sides of the counter with optimal spacing for maximum detector efficiency.
The software converts the corrected count rate to 240Pu-effective (combination of 238Pu, 240Pu, and 242Pu) and calculates the total measurement uncertainty.
The counter's neutron detection efficiency is 30% for 252Cf neutrons emitted in the center of the assay cavity. The spatial response of the counter is uniform. Variations from the mean efficiency are less than 3% for totals (non-coincident neutrons). An optional drum rotator provides additional smoothing of non uniformities in response due to the rectangular shape of the assay chamber.
It is possible to reduce the matrix effects by the use of the Add-A-Source (AAS) technique. An illustration of the AAS measurement is shown in Figure 1. The AAS introduces a small 252Cf source into the sample chamber at the end of the passive assay and compares this result with an empty chamber value. The impact of the waste matrix is evaluated from this relative measurement and an appropriate correction is applied. The 252Cf source for the AAS correction is stored above the counter in a HDPE shield. Measurements indicate that the presence of the 252Cf source has no significant impact on the background readings. The source positioning is controlled by the software.
- 208 liter (55 gallon) drum counter
- >30% efficiency
- <0.7 cps coincidence background at sea level
- MDAs of less than 20 nCi/g
- Automated loading and unloading
- Add-A-Source correction
- Coincidence or multiplicity counting
WM3400 Passive Neutron Slab Counter
The WM3400 measures the plutonium content in 200 L (55 gal) drums by detecting coincidence neutrons from the spontaneous fission of the even numbered isotopes of plutonium. The counter is designed to make a go/no-go measurement. A JSR-12 Neutron Coincidence Analyzer is required for coincidence counting, but not included with the WM3400.
The WM3400 is a slab of high-density polyethylene attached to a cart. A drum positioning fixture is attached to the front of the polyethylene slab. The drum is rolled up to the counter and the measurement is made. A shelf on the back of the cart can be used to hold the JSR-12, and the cart tabletop is available for a portable computer and printer (not included with WM3400).
Six 3He tubes are placed in the slab of high-density polyethylene. The tubes are arranged in a single row, wired together and connected to one JAB-01 Amplifier/Discriminator circuit board. The JAB-01 is mounted inside a high voltage junction box. An LED indicator on the outside of the junction box indicates the proper operation of the JAB-01 channel. Electrical connections between the WM3400 and the JSR-12 include +5 V, HV, and a single "ORed" output signal.
- Designed for passive neutron go/no-go measurement of plutonium in 200 L (55 gal) drums
- Drum positioner on front of polyethylene body for repeatable positioning of counter
- Fast Amptek® electronics
- Six 3He detectors
WM3210 Passive/Active Neutron Cf-252 Shuffler System
The WM3210 is based upon a design by Los Alamos National Laboratory1, and is available commercially from CANBERRA's Applied Systems Division through a technology transfer agreement with LANL. The Model WM3210 Passive/Active Neutron (PAN) Shuffler uses a high speed transfer mechanism to shuffle a 252Cf interrogation source between a source shield assembly and the counting chamber, giving it the ability to be used for both passive and active neutron coincidence counting of fissionable materials.
Because shuffler-type instruments can be used for the non-destructive assay (NDA) of small amounts of both uranium and plutonium in a wide variety of forms and matrix materials, they are ideal for analyzing waste materials produced by facilities which handle fissile material and for safeguards accountability measurements. In addition, the design of the WM3210 allows it to also be used for samples as large as spent fuel assemblies, where the presence of large amounts of activation products make gamma assay impractical.
- Unique 252Cf Shuffler mechanism for both Active and Passive neutron coincidence counting of 200 L drums
- Active mode sensitivity1, 1000 second count time:
- Fast neutrons: 300 mg 235U
- Thermal neutrons: 3 mg 235U
- Passive mode sensitivity1, 1000 second count time: 4 mg 240Pu
- Rugged mechanical design for in-plant use
- Fast Teleflex source shuffling mechanism with 400 ms transfer time
- Three rpm turntable for barrel rotation
- Sixty-four 3He tubes for 17.5% detection efficiency
- PC-based control and analysis system
WCAS - Waste Crate Assay System
The Waste Crate Assay System (WCAS) is a passive neutron coincidence counter designed for low level waste assay to determine the transuranic (TRU) activity of contaminated solid waste in containers up to 1.43 x 1.43 x 1.20 m crates. The WCAS provides simultaneous passive neutron coincidence and high resolution gamma isotopic analysis allowing rapid characterization of plutonium wastes.
The WCAS is based on the CANBERRA Waste Drum Assay System (WDAS) design with integrated High Resolution Gamma-Ray System. Results from individual neutron and gamma-ray assays are combined automatically by the NDA-2000 software. Because the assays are performed in the same system in a single assay sequence there is no confusion over item ID or modification of sample contents between assays.
The system is designed to be operated as an automated counting system which can process batches of drums, or can be incorporated in a facility process line. The following sections describe the various assay sub-systems, hardware, software and indicate typical performance characteristics.
Components of the system include the neutron counter with 3-He detector, Amptek based fast preamplifier/discriminator circuit boards (Model JAB-01), coincidence electronics, computer hardware, high resolution gamma detectors, digital signal processing for the gamma-ray analysis and application software.
The WCAS shield assembly provides a 4p, 20 cm thick High Density Polyethylene (HDPE) moderator/shield as a measurement chamber for the drums and crates. The neutron shield provides an assay chamber that minimizes the effects of outside neutron radiation levels. As configured the neutron shielding is also effective for reducing the gamma-ray background levels (equivalent to a 1 in. thick steel shield) enhancing the performance of the MGA isotopic analysis at low Pu mass loadings.
The software converts the correct neutron coincidence rate to 240-Pu effective. The plutonium isotopic abundances are then calculated and used to convert the measured 240-Pu effective mass to a total plutonium mass.
- Combines multiple assay techniques
- Passive neutron multiplicity coincidence counting
- High resolution isotopic gamma-ray analysis
- Crate sizes up to 1660 L (1.4 x 1.4 x 1.2 m)
- Scalable to larger containers
- Fully automated operation and analysis
- 18% efficiency for 240Pu fission neutrons
- MDAs of less than 6 mg 240Pu
- Multiple HRGS detectors
- 252Cf Add-A-Source moderator correction
- NDA-2000 Non-Destructive Analysis Software
- Systèmes Gamma de mesures de déchets
- Systèmes Neutron de mesures de déchets
- WM3500 Curved Passive Neutron Slab Counters
- JCC-41 Flat-Squared Neutron Coincidence Counter
- WM3100 High Efficiency Passive Neutron Counter (HENC)
- NDA 2000 Non-Destructive Assay Software
- N93 Large Passive Neutron Slab Counter
- WM3400 Passive Neutron Slab Counter
- WM3210 Passive/Active Neutron Cf-252 Shuffler System
- WCAS - Waste Crate Assay System
- Systèmes Gamma/Neutron de mesures de déchets
- Systèmes spéciaux clés en main
- Logiciel systèmes
- Systèmes de mesure safeguard Neutron
- Systèmes de mesure in situ