Fundamentals of passive nondestructive assay of fissionable material

Abstract

Since 1966 the Atomic Energy Commission and the Los Alamos Scientific Laboratory have pioneered the development of new technology for inspection, accountability, and surveillance of special nuclear materials (SNM) to meet foreseen requirements for stringent control of these materials on a time scale consistent with the projected growth of the nuclear industry.Today's urgent need for tight SNM controls, long foreseen by safeguards people, has recently been underscored by widespread publicity on the problems of nuclear materials theft, diversion, terrorism, etc. The key to an effective balanced national system of stringent safeguards lies in the new nondestructive assay (NDA) techniques and instrumentation being developed and now beginning to be applied throughout the nuclear industry. This naw instrumentation, coupled with advances in low-cost computers will provide automated on-line accountability and control of nuclear materials on an essentially real time basis. This automated in-plant control of SNM promises not only stringent, economic safeguards, but also other important economic benefits through upgraded process and quality control, criticality aafoty, and the reduction or elimination of costly shutdown and cleanout procedures at inventory time.Experience to date in the development, evaluation, and inplant deployment of NDA equipment: has shown that an array of specialized NDA instrumentation is required to measure the many different forms, compositions, and containments in which SNM appears in the nuclear fuel cycle. The task of successfully implementing and transferring this new technology to th« nuclear industry is indeed prodigious. STEClearly the most important single factor i:.i the successful transfer of NDA technology is the training of personnel in practical use of instruments. To that end, the U.S. Atomic Energy Commission established the Nondestructive Assay Training Program at Los Alamos in the fall of 1973. Ahhough enrollment was initially limited to AEC inspectors, future course offerings (on a semiannual basis) will be available to the growing number of users of NDA equipment in both government and private sectors of the nuclear community. Courses are designed to cover both the underlying principles and the use of NDA instruments with emphasis on practical assay and verification measurements of specific interest to attendees. A formal training manual is prepared and used extensively with each course. This first manual provides a general reference on. the use of portable NDA instrumentation together with a summary of measurement principles basic to the understanding of other more advanced NDA techniques, both passive and active.The U.S. Atomic Energy Commission Nondestructive Assay Training Program provides an excellent opportunity far direct exchange of ideas, discussion of special problems, etc., between the developers and users of NDA instrumentation. Such direct person-to-person interaction has proved by far the most effective method of NDA technology transfer and provides one of the majo...

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