Year
2000
Abstract
To meet MPC&A contract terms and programmatic transparency objectives within the Cooperative Threat Reduction Treaty between the US and Russia, it is important to measure the material intended for down blending for its total uranium concentration and for its 235U enrichment. A two-measurement technique provides the best combination of overall measurement accuracy, flexibility, ease of use, ready commercial availability, and economy of operation. Gamma spectrometric systems that can measure the 235U enrichment are readily available commercially. Active neutron counters for total uranium determinations are also readily available, but generally not in the size required for this program objective. Although there is no commercial off-the-shelf version of such a counter, neutron multiplicity counters are functionally very modular and it is common practice for the commercial companies that build them to produce them in an “as needed” form-factor (within sensitivity parameters). The counter that was found to meet the necessary design criteria is based on a high efficiency passive neutron counter which has been modified to include an excitation source, similar to the one in the Active Well Coincidence Counter (AWCC). In this paper, we will report on the design and test results of a large scale Hexagonal High Efficiency Multiplicity Counter that was recently built for a mobile nuclear material characterization ISO container for deployment in Russia.