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ANTECH Model 2300
Combined Passive Neutron/Gamma
Drum Monitor
Instrument supplied with multiple gate neutron coincidence Pu analysis
software with wide range calibration function
For a number of Pu bearing waste streams and sample types the
instrument can perform absolute multiplicity assay independent of sample
matrix and without calibration
Automated measuring procedure employing user friendly Windows NT based
software
Suitable for PCM waste with high alpha ratio (a=10).
Semi-automatic drum loading / unloading.
 ANTECH Series 2200 Passive neutron Multiplicity Drum Monitor
(nMDM) is a comprehensive measurement system for the determination of
plutonium mass in intermediate/low level waste in 220 liter drums. The
operation of the instrument is based on passive neutron
coincidence/multiplicity counting. User friendly Windows NT software
controls the semi-automatic drum loading, the neutron data acquisition and
the analysis algorithms. The system can be integrated with a germanium
gamma-ray drum scanner for Pu isotopic ratio determination using PC/FRAM or
other isotopic analysis code.
The neutron detection system employs 64 He-3
tubes grouped in 16 rectangular polyethylene modules each with 4 tubes
connected to a high voltage junction box containing an Amptek charge
sensitive amplifier/discriminator circuit and connections for high voltage,
low voltage and signal cables. The detector modules are fixed inside an
outer shield of polyethylene which is 210 mm thick and covered in stainless
steel. The internal and external module surfaces are covered in cadmium to
absorb re-entrant thermal neutrons. The cadmium can be removed to increase
the detection probability for coincidence and total counting for very low
level detection.
The basic design is flexible and can be
modified to increase the number of tubes (increase counting efficiency), to
adjust the moderator thickness (vary shielding and die-away time) or for
gamma-ray active waste, lead shielding may be added. The nMDM is optimized
for use with the ANTECH 1000 Series neutron Time Correlation Analyzer (TCA)
multiplicity counter.
For pair correlation counting in neutron
coincidence mode the frequency histogram is used to generate the 'Reals'
rates for each of the 16 gates. Each 'Reals' rate can be used with a
multi-gate calibration function to determine the Pu-240eff mass and hence
the total Pu mass. For a wide range of Pu containing materials (PCM) such as
PuO2 and PCM with unitary neutron multiplication (M=1), triple neutron
correlation may be used in absolute multiplicity counting mode. In these
cases Pu-240eff mass and total Pu mass are determined without the use of a
calibration function and the matrix characteristics are determined from the
measured detection efficiency.
Specifications
- 64 He-3 detector tubes, 25.4 mm x 1.0
m at 4 Atm.
- Detector efficiency: 20% (64 tubes).
- Die-away time: 68 ms.
- Dimensions: (L x W x H) 3.3 m x 1.8
m x 2.1 m
- Operating Voltage: 1600 V (4 Atm. He-3)
- Estimated Sensitivity at sea level:
Multiplicity Counting (n triple correlation) - 50 - 100
mg Pu-240eff (Cd fitted)
Coincidence Counting (n pair correlation) - 10 - 50
mg Pu-240eff (Cd fitted)
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