The Argonne National Laboratory and Sandia National Laboratory have recently installed an activated barrier, the Access Denial System (ADS) for the upgrade of safeguards of special nuclear materials. The technology of this system was developed in the late 70's by Sandia National Laboratory-Albuquerque. The installation was the first for the Department of Energy. Subsequently, two additional installations have been completed. The Access Denial System, combined with physical restraints, provide the system delay. The principal advantages of the activated barrier are: (1) it provides an order of magnitude improvement in delay over that of a fixed barrier, (2) it can be added to existing vital areas with a minimum of renovations, (3) existing operations are minimally impacted, and (4) health and safety risks are virtually nonexistent. Hardening of the vital areas using the ADS was accomplished in a cost-effective manner. 3 references, 1 figure, 1 table.

The polyperfluoroethers are compatible with uranium hexafluoride (UF/sub 6/) and are suitable for use in diffusion pumps and in mechanical vacuum pumps which rely on oil as both the lubricant and the seal. The UF/sub 6/ is soluble in all fluids with which it is compatible. Because a number of vacuum pumps in the BOP facilities of the GCEP plant employ these perfluoroether oils as the working fluid and have oil chambers which are large, questions have been raised as to the relationships governing the solubility of UF/sub 6/ in these materials and the maximum quantities of UF/sub 6/ which could be dissolved in these oils under credible accident conditions. This report summarizes these solubility relations and the interaction of the UF/sub 6/ solubility and the pumping capability of this type of vacuum pump. It will be shown that, whereas the solubility of UF/sub 6/ in Fomblin Y25 fluoroether fluid under a UF/sub 6/ pressure of 760 torr and at the pump operating temperature of 160/sup 0/F is about 500 g of UF/sub 6/ per liter of oil, the system controls are such as to isolate the system from the pumps before the quantity of UF/sub 6/ dissolved in the …

Four-point bending studies have been continued to compare primary creep response of FZ and CZ silicon above 1200/sup 0/C. Results suggest that silicon can be treated as a completely plastic solid in the temperature range 1200 to 1400/sup 0/C in its response to thermal stress generated during sheet growth. In the stress range of 5 to 15 MPa, the strain rate dependence on stress is epsilon approx. sigma/sup 10/, and appears to be essentially temperature independent. Work is underway to compare stresses predicted for two different thermal models used for temperature field calculations. Stress analysis has been performed to illustrate the dependence of sheet stresses on growth parameters such as sheet width, thickness and growth speed, and the coupling of these parameters to the details of the temperature field calculations used as input to the stress model. The construction of a simplified EFG ribbon system to be used to test the stress model and to investigate means to achieve low stress growth configurations is completed. The first results of measurement of residual stress distributions in EFG sheet using shadow-Moire interferometry have been obtained at the University of Illinois.