The Universal Gamma Scanner(UGS) for cans combines the functions of Pu isotopic ra-

tio analysis and Tomographic Gamma Scanner (TGS) in a single automated mobile in-

strument. The instrument can be used for combined or separate measurements and is in-

tended for use in Safeguards and for waste assay.

Isotopic ratio analysis of Pu is performed using PC/FRAM code developed at the Los

Alamos National Laboratory (LANL). An 8k channel spectrum is obtained during the

TGS scans and this data is used to obtain the isotopic ratios, including the ratio of U, Am

and other radionuclides to Pu. The isotopic ratio result data can be used for safeguards or

accountancy purposes or combined with either Pu-240 effective data (from neutron meas-

urements) or specific power data (from calorimetry measurements) to determine total Pu

The second measurement component of the instrument is the transportable Tomographic

Gamma Scanner (TGS) which was developed by LANL in the early 1990's for the US

DOE. The TGS uses transmission corrected, single photon emission computerised axial

tomography to determine the spatial distribution and quantity of radio-nuclides using

High Resolution Gamma-ray Spectroscopy (HRGS). The technique represents a consid-

erable advance over the Segmented Gamma Scanner (SGS) technique through the imple-

mentation 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 attenua-

tion 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 radioiso-

topes within the sample. Two pass (transmission followed by emission) measurements

are performed.

Also, because 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.

Automation of 3 axes of motion

30-200,Ci Se-75 transmission source

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Germanium Coax detector efficiency

Cd-109 dead time source

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TGS analysis: typically 4800 4k chan-

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Digital MCA based on the ORTEC

nel spectra for each measurement

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DSPec Plus

Isotopic Analysis: one 8k channel

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Overall instrument envelope: 1520mm

emission spectrum

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User friendly software rune under

long,710mm wide and 1070mm high

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windows NT4 and meets Nuclear soft-

Variable sample can size to a maxi-

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ware QA requirements of NQA-1

mum of 200mm diameter x 350mm

(required by WIPP certification)

(8"x 14") and 20kg in weight

Ethernet communication from opera-

Trolley mounted mobile unit for

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tor computer control console

measuring cans