The Ion Beam Facility operated for 6000 machine hours last year, ranging in energy from 300 Kev to 24 Mev. Improvements include cryopumps replacing diffusion pumps, a rebuilding of the tandem chopper electronics and the vertical's corona charging system. Methane molecules were successfully accelerated by the vertical in quantities of hundreds of nanoamperes. Two replacement magnet power supplies on the tandem and a completely new capacitor shell regulator on the vertical are soon to be installed.

Present ion sources produce deuterium ions plus small amounts of impurity ions including oxygen. The oxygen current is readily trapped by the Mirror Fusion Test Facility-B (MFTF-B) plasma and represents a severe energy loss mechanism. A pure-beam source-neutralizer has been designed by LLNL for the MFTF-B. This concept uses momentum separation by closely coupling an electromagnet to the source to purify the beam. This design requires a low pressure in the neutralizer, implying a long length and a large diameter for high conductance. Present designs require a 55-in. diameter by 60-in. long magnetically shielded region. This shield encloses the source and the separator magnet, and acts as the neutralizer duct for the beam. The fringe fields from the MFTF-B magnets penetrate the pure-beam neutralizer along the beamline axis. Field strengths on the order of three hundred gauss must be reduced to less than 6 gauss axial and 0.2 gauss transverse to the beam. Conventional single and double layer shielding designs require excessive amounts of permeable material. Multiple layer shields using a soft iron outer shield with a highly permeable inner shield require a 4 3/4-in.-thick outer shield. We have rejected this as a possible shielding solution. Active shielding, using two …

The general consensus of the seven reviewers is that occupational exposures at Lawrence Livermore National Laboratory have not been established as a causal factor for the observed excess of malignant melanoma. Several observations support the impression that some or all of the observed melanoma excess may be attributable to intense surveillance and enhanced detection of early stage melanoma lesions. Since the incidence of melanomas among Laboratory employees has not diminished, an early harvesting effect is unlikely. This suggests the distinct possibility that localized, in situ melanomas that would normally not be detected are being reported, and that in the absence of this enhanced detection, many of these early stage lesions would show little or no clinical progression. This phenomenon would explain the continued high incidence of melanomas in the absence of a physical or chemical inciting cause. A key point in this reasoning is the issue of the rate of growth of early stage melanomas, and this point remains a key question for study. Even if the observed excess cannot be explained by detection bias, the reviewers agree that the Austin and Reynolds' study does not make a convincing case for occupational factors being a cause of the high melanoma …

An economic model of a laser fusion commercial power plant is used to identify the design and operating regimes of the driver, target and reaction chamber that will result in economic competitiveness with future fission and coal plants. We find that, for a plant with a net power of 1 GW/sub e/, the cost of the driver must be less than $0.4 to 0.6 B, and the recirculating power fraction must be less than 25%. Target gain improvements at low driver energy are the most beneficial but also the most difficult to achieve. The optimal driver energy decreases with increasing target technology. The sensitivity of the cost of electricity to variations in cost and performance parameters decreases with increasing target technology. If chamber pulse rates of a few Hz can be achieved, then gains of 80 to 100 will be sufficient, and higher pulse rates do not help much. Economic competitiveness becomes more difficult with decreasing plant size. Finally, decreasing the cost of the balance of plant has the greatest beneficial effect on economic competitiveness. 6 refs., 5 figs., 2 tabs.

In the Cascade inertial fusion reactor, the innermost blanket zone consists of solid granules of C or BeO. The x rays from a fusion pulse of 300 MJ will vaporize up to 1 kg of material. The temperature of this vaporized material may reach 1 to 2 electron volts. The CONRAD code was used to calculate the energy and mass exchange between this hot plasma and the cold wall until complete recondensation of the material reduces the chamber particle density to 3 x 10 V cm T, which is required for propagation of the next laser pulse. Our calculations indicate that recondensation times are in the few to tens of milliseconds range even if only the first layer of granules is available for recondensation. Gas flow calculations indicate that several layers of granules should be available for recondensation. We discuss phenomenology, not currently in the CONRAD model, that could lead to increased recondensation times. 17 refs., 5 figs.

The Fast Flux Test Facility is a 400 MW Thermal Sodium Cooled Fast Reactor operated by Westinghouse Hanford Company for the US Department of Energy. During startup testing in 1979, the sodium level in one of the primary sodium pumps was inadvertently raised above the normal height. This resulted in distortion of the pump shaft. Pump replacement was carried out using special maintenance equipment. Nuclear radiation and contamination were not significant problems since replacement operations were carried out shortly after startup of the Fast Flux Test Facility.

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