radius segments correspond to MITL sections without axial electric field. This design assures constant current flow over the entire length of SABRE. The cathode electrode is 9.6-m long and includes the voltage adder (6-m long) and a constant radius (2.2 cm) extension 3.2 m in length. We present the design, analysis, and first results of the high brightness electron beam experiments currently under investigation at Sandia National Laboratories. The anticipated beam parameters are the following: energy 12 MeV, current 35-40 kA, rms radius 0.5 mm, and pulse duration 40 ns FWHM. The accelerator is SABRE [I], a pulsed LNA modified to RADLAC 11. To generate beams of millimeter sizes, the diode must be immersed in solenoidal fields of 20-30 Tesla [5,6,7]. Figure 2 shows a schematic diagram of the diode design, including the solenoidal magnet. The shape of the fringe field is tailored by a 2-cm thick a l e n u m cylinder 25-cm iflner radius coaxially enclosing the entire diode assembly.

Estimates of potential radionuclide releases from HLW storage facilities in geologic formations are an integral part of the technical basis for the regulation of nuclear waste disposal. We have attempted to assess the importance of the variation of several variables and model assumptions to the calculation of radionuclide discharge from hypothetical repositories. The conceptual models of the repository sites are consistent with our current understanding of the characteristics of the geologic environments being studied by the Department of Energy. It must be stressed that we have not attempted to accurately model any real sites; at the present time, the available data are not sufficient for this purpose. Large uncertainties exist in the characterization of the solubilities and sorption of radionuclides, in the description of the regional and local hydrogeology and in the mathematical treatment of contaminant transport in the presence of fracture flow and matrix diffusion. The fraction of waste that could be accessed by breaching the repository, the effects of mixing processes within the facility and the probability of human intrusion are not known. We have completed preliminary calculations of potential radionuclide discharges from hypothetical repositories in tuff and bedded salt [1,2]. Our theoretical approach and computational methods are illustrated in this paper with examples for a repository in volcanic tuff. We also briefly discuss the importance of radionuclide source term assumptions to the calculations for a bedded salt repository.

The proposed Jupiter accelerator is a -10-MV, 500-TW system capable of delivering 15-MJ kinetic energy to an imploding plasma radiation source (PRS).lS2 The accelerator is based on Hemes-1113 technology and contains 30 identical inductive voltage adder modules connected in parallel. The modules drive a common circular convolute electrode system in the center of which is located an imploding foil. The relatively high voltage of 8-10 MV is required to compensate for the voltage differential generated across the load due primarily to the fast increase in current (L Wdt) and to lesser extent to the increasing inductance (I dL/dt) and resistive component of the imploding foil. Here we examine the power flow through the device and, in particular, through the voltage adder and long MITL. Analytical models, such as pressure balance and parapotential flow, as well as circuit and PIC codes, were utilized. A new version of the TWOQUICK PIC4 code, which includes an imploding, cylindrical foil as load, was utilized to compare the power flow calculations done with SCREAMER5 and TRIFL.6 The agreement is very satisfactory and adds confidence to the Jupiter design. In addition, an experimental validation of the design is under way this year (FY95) with Hemes III. Long extension MITLs are connected at the end of the voltage adder with inductive and diode loads to benchmark the above design codes. In this paper we outline the accelerator's conceptual design with emphasis on the power flow and coupling to the inductive load and include preliminary results of Hemes-111 experimental design validation?

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