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In this study we examine the combination of a He-O glow discharge with heating as a possible technique to remove deuterium from TFTR tiles. Samples were cut from a relatively large area containing a uniform codeposited layer of deuterium and carbon. Auger/SEM was used to generate micrographs of each of the samples. The samples were also examined using Rutherford backscattering to determine the near surface composition. Individual samples were then exposed to a He-O glow discharge while being heated. After the exposure, the samples were returned for Auger/SEM and RBS of the same areas examined prior to the exposure. Comparing the samples before and after exposure revealed that the amount of the codeposited layer removed was significantly less than 1 lm. Removal rates this low would suggest that He-O glow discharge with heating is insufficient to remove the thick layers predicted for ITER in a timely fashion. Published by Elsevier B.V.

SummaryThe detection of neutron sources from a considerable distance constitutes a problem that must be treated separately from the bulk of other neutron-detection applications. This report analyzes this problem, describes a number of possible approaches, and describes the design and construction of a square-meter detection system using the approach of moderator-free directional neutron detection. Although experimental results are not the focus of this report, a few preliminary results are offered in the last section. Both theoretical and preliminary experimental results confirm that useful detection of neutron sources for national-security applications is relatively easy at a distance of 50 meters, yet becomes somewhat challenging from a distance of 100 meters.The square-meter detection system designed for this effort was intended to be, in decreasing order of priority, optimally capable of neutron-source detection at 100 meters, lightweight and easy to use, and low in cost. Thus, the majority of design decisions were driven by the need to maximize sensitivity for remote source detection. Several surprises resulted from this design effort. First, we discovered that ' %, rather than cadmium or gadolinium, must be used as a shielding material. Second, we discovered that a relatively open collimator is best for remote detection. These and other design decisions are described in detail in the third section of this report. The final detector weighs roughly 45 kg and incorporates hardware with a cost of roughly $loOK. Of course, lighter or cheaper detection systems could be designed with some reduction in sensitivity. As designed, our 1-square-meter moderator-free detection system is expected to be superior to conventional moderate-and-capture detection for some applications.

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Accurate energy calibration is critical for the timeliness and accuracy of analysis results of spectra submitted to National Reachback, particularly for the detection of threat items. Many spectra submitted for analysis include either a calibration spectrum using 137 Cs or no calibration spectrum at all. The single line provided by 137 Cs is insufficient to adequately calibrate nonlinear spectra. A calibration source that provides several lines that are well-spaced, from the low energy cutoff to the full energy range of the detector, is needed for a satisfactory energy calibration. This paper defines the requirements of an energy calibration for the purposes of National Reachback, outlines a method to validate whether a given spectrum meets that definition, discusses general source considerations, and provides a specific operating procedure for calibrating the GR-135.