Two prototypes electrofibrous filters were designed, built and evaluated in laboratory tests and in field installations. These prototypes were designed for use in nuclear ventilation ducts as prefilters to HEPA filters. One prototype is designed to be a permanent component of the ventilation system while the other is a disposable unit. The disposable electrofibrous prefilter was installed in the exhaust stream of a glove box in which barrels of uranium turnings are burned. Preliminary tests show the disposable prefilter is effectively prolonging the HEPA filter life.

An automatic on line sewage effluent monitoring system has been developed. A representative fraction of the total waste stream leaving the site is monitored for pH, radiation, and metals as it passes through a detection assembly. This assembly consists of an industrial pH probe, NaI radiation detectors, and an x-ray fluorescence metal detector. A microprocessor collects, reduces and analyzes the data to determine if the levels are acceptable by established environmental limits. Currently, if preset levels are exceeded, a sample of the suspect sewage is automatically collected for further analysis, and an alarm is sent to a station where personnel can be alerted to respond on a 24-hour basis. Since at least four hours pass before LLNL effluent reaches the treatment plant, sufficient time is available to alert emergency personnel, evaluate the situation, and if necessary arrange for diversion of the material to emergency holding basins at the treatment plant. Information on the current system is presented, and progress is reported in developing an on-line tritium monitor as an addition to the assembly.

During the past year, several magnetic pulse compression systems have been built and applied to the ETA accelerator. In view of their excellent performance, a non-linear magnetic system has been adopted for the ATA grid drive in place of the spark gap driven Blumlein. The magnetic system will give us a much higher reliability and greater flexibility by being independent of the high pressure gas blown system. A further advantage of this system will be the capability of achieving higher rep-rates in case of a future upgrade. System design and performance under burst mode will be described.

The pressure on the boundary of the Lawrence Livermore National Laboratory's (LLNL) tandem mirror (TMX-U) plasma experiment is difficult to trace for several reasons: (1) the TMX-U boundary is in the high vacuum range (10/sup -5/ to 10/sup -6/ Pa) and requires an ionization gauge; (2) the boundary includes high-energy neutral particles and radiation, so the gauge must be optically baffled from the plasma; (3) the gauge must be shielded from the magnetic flux density of 0.03 T; (4) maximum conductance to the gauge must be preserved so that the time response remains about 1 ms; (5) a fast electrical circuit is required to measure the small ion-current changes at a rate consistent with the geometrical and experimental time constant of 1 ms. We have developed solutions to these limitations, including fast ionization gauge (FIG) circuitry for the remote gauge operation and the CAMAC system for recording the pressure-time history in the TMX-U computer data base. We also give some examples of actual fast pressure histories during plasma operation.

This paper discusses recent theoretical work on the equilibrium and stability of quadrupole tandem mirrors in the paraxial limit. It reviews calculations of three-dimensional equilibria by means of a ..beta..-expansion technique which lead to an understanding of the important role played by parallel currents and the corollary importance of careful design of the structure of the vacuum geodesic curvature. The previously predicted scaling with central-cell length of the finite-..beta.. distortion of vacuum flux surfaces is shown to saturate because of finite orbit effects. An adaptation to tandem geometries of the reduced MHD technique for calculating high-..beta.. three-dimensional equilibria is described. This approach uses the paraxial expansion to resolve the time-dependent relaxation to equilibrium into three distinct timescales on which the motion can be followed independently. Regarding stability, it is shown that kinetic effects suppress ballooning modes of short-to-moderate perpendicular wavelength; in the limit that such effects are dominant only rigid modes are possible. The stability of the latter modes is investigated within the context of the energy principle. Results of equilibrium and stability calculations for the TMX-U and MFTF-B experiments at Livermore are presented.

Deep geologic repositories are being widely studied as the most favored method of disposal of nuclear waste. Scientists search for repository sites in salt, basalt, tuff and granite that are geologically and hydrologically suitable. The systematic evaluation of the safety and reliability of deep geologic disposal centers around the concept of interacting multiple barriers. The simplest element to describe of the geologic barrier is the physical isolation of the waste in a remote region at some depth within the rock unit. Of greater complexity is the hydrologic barrier which is determined by the waste dilution factors and groundwater flow rates. The least understood is the geochemical barrier, identified as a series of waste/water/rock interactions involving sorption, membrane filtration, precipitation and complexing. In addition to the natural barriers are the engineered barriers, which include the waste form and waste package. The relative effectiveness of these barriers to provide long-term isolation of nuclear waste from the human environment is being assessed through the use of analytical and numerical models. The data used in the models is generally adequate for parameter sensitivity studies which bound the uncertainties in the release and transport predictions; however, much of the data comes from laboratory testing, and …

The local structure at individual ion sites in simple and multicomponent glasses is simulated using methods of molecular dynamics. Computer simulations of fluoroberyllate glasses predict a range of ion separations and coordination numbers that increases with increasing complexity of the glass composition. This occurs at both glass forming and glass modifying cation sites. Laser-induced fluorescence line-narrowing techniques provide a unique probe of the local environments of selected subsets of ions and are used to measure site to site variations in the electronic energy levels and transition probabilities of rare earth ions. These and additional results from EXAFS, neutron and x-ray diffraction, and NMR experiments are compared with simulated glass structures.