Active nondestructive assay of nuclear materials: principles and applications

Abstract

conclusions of the chapter, and a reference list. This system of organization will allow the reader to select, within some limits, those parts of the text which are of specific interest to him without his having to read the entire book. The first buds of this book appeared several years ago; however, the support given in the last few years by the NRC Office of Standard Development through Mound Laboratory of Monsanto Research Corporation was essential to its relatively early conclusion. I would therefore like to express my thanks to Messrs. P. Ting, E. Selleck, and R. J. Jones of NRC. The patience and indulgence of Dr. W. Strohm, who monitored the contract for Mound Laboratory are deeply appreciated as well as his critique and comments. I would also like to acknowledge the help given to me in preparing this manuscript through discussion, written material, and photographs: the safeguards group (Ql) at Los Alamos Scientific Laboratories was very helpful, especially Drs. R. Walton and H. Menlove.

Active Interrogation Using Electronic Neutron Generators for Nuclear Safeguards Applications

“…[7] A simple flow sheet showing the major steps involved in spent nuclear fuel reprocessing is shown in Figure 1 together with examples of where active interrogation has been used for process monitoring and for safeguards measurements. However, active interrogation monitoring techniques have not seen widespread application in today's fuel reprocessing facilities, most likely because alternate technologies have been found to achieve the same goals and because active techniques are typically more complicated and more expensive than comparable passive techniques.…”

A Conceptual Design Study for Active Nondestructive Assay System by Photon Interrogation for Uranium-Bearing Waste with MVP Code and Evaluated Photonuclear Data

“…2,3) The major uranium isotopes have much longer half lives than the other actinides such as plutonium isotopes. This feature of uranium isotopes often makes quantitative determination of them in the waste to be difficult by means of detecting characteristic radiations spontaneously emitted from them with the nondestructive manner.…”

Using electronic neutron generators in active interrogation to detect shielded fissionable material

“…Using an external neutron radiation source to probe a suspect SNM-containing object produces additional SNM signatures, generally stronger and less ambiguous than the passive signatures, which can allow positive/negative determinations to be made quicker and with lower material detection limits than with passive screening alone. [5][6][7][8][9][10][11][12][13][14][15][16][17] The most commonly used active neutron interrogation techniques for SNM detection involve the use of electronic neutron generators (ENGs), which produce nearly monoenergetic fast neutrons at either 2.5 or 14.1 MeV, operating as pulsed neutron sources. For these measurements the ENGs generate short pulses of neutrons, ranging from 0.01 ms to 1 ms, and typically pulse at frequencies on the order of ~100 Hz.…”

“…[5][6][7][8]10,11,15] These measurements can include the detection of gamma rays and/or neutrons and the technique has proven useful in many situations. One challenge with this technique is that the intensity of these post-fission 'delayed' signatures is not high, at least in comparison with the gamma-ray and neutron signatures originating directly from fission.…”

“…[7][8][9][12][13][14]16,17] During this period fission is still occurring and detectors suited for measuring these fission signatures directly can be used. The intensity of these prompt fission signatures is much stronger than those from the fission products used in the delayed measurements.…”