ORTEC - Antech Model 3800 Combined Tomographic Gamma Scanner (TGS)

ANTECH Model 3800
Combined Tomographic Gamma Scanner (TGS) for 400 Litre Drums

The transportable Tomographic Gamma Scanner (TGS) was developed by the Los Alamos National Laboratory (LANL) in the early 1990s for the US DOE. The TGS uses transmission corrected, single photon emission computerized axial tomography to determine the spatial distribution and quantity of radio-nuclides using High Resolution Gamma-ray Spectroscopy (HRGS). The technique represents a considerable advance over the Segmented Gamma Scanner (SGS) technique through the implementation of a sample translation axis in addition to vertical scanning and rotation axes.

A Se-75 transmission source allows the determination of a 3-D spatial map of the attenuation coefficient at any energy by interpolating between the gamma-ray peaks of Se-75 at several energies. Once the attenuation coefficient maps have been established for the sample, emission tomography is used to determine the distribution of selected radioisotopes within the sample. Two pass (transmission followed by emission) measurements are performed.

A further advantage of the TGS technique over the SGS is the ability to produce both attenuation coefficient and source (emission) images for each vertical segment of the sample can or drum.

Typically the spatial resolution for the emission image is about 6cm for drums and 3 cm for cans.

As the attenuation and source distribution matrix is known more accurately than in an SGS, biases due to matrix and source distributions are significantly reduced. As a result, a single calibration constant can be used for the determination of isotope mass for a wide range of material and matrix types.

Isotopic ratio analysis of Pu is performed using PC/FRAM code. An 8K channel spectrum is obtained for isotopic analysis during the TGS scans.

The TGS Drum Scanner meets both US Nuclear Safeguards and DOE WIPP measurement and QA requirements

Specifications

Automation of 3 axes of motion
Cd-109 dead time source
Germanium Coax detector efficiency 50%
Adjustable collimator (cans or drums)
Digital MCA based on the ORTEC DSPEC Plus
TGS Analysis: typically 4800 4k channel spectra for each measurement
Overall instrument envelope: 1835 mm long x 1512 mm wide x 1785 mm high
Isotopic Analysis: one 8k emission spectrum
Variable sample drum and can size (maximum 400 litre)
Weight: 1200 kg
Ethernet communication from operator computer control console
Dimensions: Pillar height 2.2 m, Base 1.8 m wide x 2.1 m deep
30-200mCi Se-75 transmission source
User friencly software runs under Windows NT4 and meets Nuclear Software QA requirements of NQA-1 (required for WIPP certification)

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