A calculation of the two X-ray K-shell photoionization cross section of chlorine will be presented and the feasibility of an experiment will be discussed.

A calculation of the two X-ray K-shell photoionization cross section of chlorine will be presented and the feasibility of an experiment will be discussed.

The increase in the BBU threshold current is very important for the high and medium energy electron linacs because of a larger operating current attainable or a smaller emittance available at certain operating current. For this purpose, many means can be used, among which the improvement in the accelerating structure itself is always fundamental. SLAC's three-meter long section is unique with truly constant gradient performance. The theoretical analyses and operating experiences at SLAC have indicated that detuning the Nos. 3, 4 and 5 cavities of some sections by 2 or 4 MHz for TM/sub 01/ wave had considerably raised the BBU threshold current. A method of opening four holes symmetrically distributed on disks as described in detail will get the benefits in improvement of BBU threshold current.

The effects of mechanical strain on the high-field critical current, I/sub c/, of two Nb/sub 3/Sn conductors were measured. Static strains up to 0.9 percent and cyclic strains to 0.6 percent were used; I/sub c/ was measured at fields up to 12 T. Critical current, which increased with strain in all cases, peaked at approximately 0.3 percent and decreased for higher strains. For strains less than 0.8 percent, the change in I/sub c/ was reversible; permanent damage only occurred in one conductor for strains near 0.9 percent. No effect of cyclic strains, 0.6 percent in amplitude, could be detected up to 500 cycles.

Heavy ion fusion requires high power to be focussed onto a small pellet. If the reactor chamber pressure is below 10/sup -4/ to 10/sup -5/ Torr, beam compression will be limited by space charge unless neutralized by co-moving electrons. If higher chamber pressures are used, the heavy ion beam will create a significant number of background electrons during its propagation and will undergo stripping. The background electrons could provide the neutralization required for high beam intensities. In this paper we will focus on the physics associated with propagation through a fully ionized hydrogen plasma, so background electron generation is not included. One-dimensional electrostatic and two-dimensional fully electromagnetic particle-in-cell simulations are presented. If a background plasma is present, we find that coinjected electrons whose purpose is to charge and current neutralize the ion beam become two-stream unstable and no longer provide the thermally cool neutralization required. Further, we find that the ion induced background electron temperature is very sensitive to the ion beam to background electron charge density ratio.

Microstructures of Si ion-implanted with Cu have been characterized by TEM after annealing. For 1.2 at.%, the Cu is trapped at planar defects, but for 10 at.%, {eta}-Cu{sub 3}Si forms and Cu diffuses at its equilibrium solubility. These observations allow proper evaluation of the binding energies of Cu to previously formed internal cavities (2.2 eV) and {eta}-Cu{sub 3}Si (1.7 eV). The 10 at.% Cu layer promotes oxidation of Si catalyzed by {eta}-Cu{sub 3}Si. The microstructures also indicate that Si implanted with {approximately}2 at.% Cu reforms epitaxially with embedded defects after 8 hr at 700C, but for {approximately}10 at.% Cu, epitaxy is not recovered after 6 hours at 600C.

This paper analyzes data for fission-energy and fusion-energy development. Neutron reactions with uranium and plutonium are discussed in particular. Instrumentation is also reviewed. (LSP)

The effect of aging upon the Babcock Wilcox (B W) and Combustion Engineering (CE) Control Rod Drive (CRD) systems has been evaluated as part of the US NRC Nuclear Plant Aging Research (NPAR) program. Operating experience data for the 1980--1990 time period was reviewed to identify predominant failure modes, causes, and effects. These results, in conjunction with an assessment of component materials and operating environment, conclude that both systems are susceptible to age degradation. System failures have resulted in significant plant effects, including power reductions, plant shutdowns, scrams, and Engineered Safety Feature (ESF) actuation. Current industry inspection and maintenance practices were assessed. Some of these practices effectively address aging, while others do not.

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The development of the LACCE, the Los Alamos computerized cost estimating system, is described. During the life of this development, complexity has oscillated back and forth between bare necessity and luxurious wants. As presently structured, LACCE offers the user a power that has been proven beneficial in LASL operations. The complexity involved has been well masked and exists largely on the computer side so that the user is comfortably unaware. The atmosphere of the environment during this development should be noted as highly significant in the success. Management, estimators and systems designers have worked side-by-side; management interest in the success of the venture was understood by all; and skills and expertise overlapped to form a chain with no missing links. It is apparent that LACCE is not complete. More powerful means of modeling and data base maintenance are foreseen already, as well as code simplification, but the existing system gives LASL managers the ability to make much better decisions than just a few years ago.

The review covers early results, recent results from nu N scattering experiments, charm production in e/sup +/e/sup -/ at high energies, D/sup +/ cross-section in e/sup +/e/sup -/ annihilation, inclusive electrons in hadronic e/sup +/e/sup -/ events, and inclusive hadron spectra and scale breaking in e/sup +/e/sup -/ annihilation. 30 references, 18 figures. (GHT)

The auroral motions and geomagnetic changes the characterize the substorm's expansive phase, maximum epoch, and recovery phase are discussed in the context of their possible associations with the dropout and, especially, the recovery of the magnetotail plasma sheet. The evidence that there may be an inordinately sudden large poleward excursion or displacement (a poleward leap) of the electrojet and the auroras at the expansive phase-recovery phase transition is described. The close temporal association of these signatures with the recovery of the plasma sheet, observed on many occasions, suggests a causal relationship between substorm maximum epoch and recovery phase on the one hand and plasma sheet recovery on the other.

We present results to date from an experiment in progress by an Irvine, Los Alamos, and Maryland collaboration at the Los Alamos Meson Physics Facility (LAMPF) beam stop. We have observed a signal consistent with nu/sub e/-e elastic scattering in a 15-metric-ton detector composed of modules of flash chambers and scintillation counters. A preliminary cross section for this process is compared to that expected from the GWS model that includes the interference between charged and neutral currents. We also set limits on the probability for exotic muon decay ..mu../sup +/..-->..e/sup +/nu/sub ..mu../anti nu/sub e/ and on the neutrino oscillation mode anti nu/sub ..mu../..-->..anti nu/sub e/ from normal muon decay ..mu../sup +/..-->..e/sup +/anti nu/sub ..mu../nu/sub e/. 4 references.

The starting point of the Hiroshima-Nagasaki Dose Reevaluation Program is the energy and directional distributions of the prompt neutron and gamma-ray radiation emitted from the exploding bombs. A brief introduction to the neutron source calculations is presented. The development of our current understanding of the source problem is outlined. It is recommended that adjoint calculations be used to modify source spectra to resolve the neutron discrepancy problem.

Hydraulic fracturing has gained in popularity in recent years as a way to determine the orientations and magnitudes of tectonic stresses. By augmenting conventional hydraulic fracturing measurements with detection and mapping of the microearthquakes induced by fracturing, we can supplement and idependently confirm information obtained from conventional analysis. Important information obtained from seismic monitoring includes: the state of stress of the rock, orientation and spacing of the major joint sets, and measurements of rock elastic parameters at locations distant from the wellbore. While conventional well logging operations can provide information about several of these parameters, the zone of interrogation is usually limited to the immediate proximity of the borehole. The seismic waveforms of the microearthquakes contain a wealth of information about the rock in regions that are otherwise inaccessible for study. By reliably locating the hypocenters of many microearthquakes, we have inferred the joint patterns in the rock. We observed that microearthquake locations do not define a simple, thin, planar distribution, that the fault plane solutions are consistent with shear slippage, and that spectral analysis indicates that the source dimensions and slip along the faults are small. Hence we believe that the microearthquakes result from slip along preexisting joints, and …

Superconducting magnets for fusion energy reactors require massive monolithic stainless steel weldments which must operate at extremely low temperatures under stresses approaching 100 ksi (700 MPa). A three-year study was conducted to determine the feasibility of producing heavy-section welds having usable levels of strength and toughness at 4.2/sup 0/K for fabrication of these structures in Type 304LN plate. Seven welding processes were evaluated. Test weldments in full-thickness plate were made under severe restraint to simulate that of actual structures. Type 316L filler metal was used for most welds. Welds deposited under some conditions and which solidify as primary austenite have exhibited intergranular embrittlement at 4.2/sup 0/K. This is believed to be associated with grain boundary metal carbides or carbonitrides precipitated during reheating of already deposited beads by subsequent passes. Weld deposits which solidify as primary delta ferrite appear immune. Through use of fully austenitic filler metals of low nitrogen content under controlled shielded metal arc welding conditions, and through use of filler metals solidifying as primary delta ferrite where only minimum residuals remain to room temperature, welds of Type 316L composition have been made with 4.2K yield strength matching that of Type 304LN plate and acceptable levels of soundness, ductility …

A workshop on applications and enhancements of the TOUGH/MULKOM family of multiphase fluid and heat flow simulation programs was held at Lawrence Berkeley Laboratory on September 13--14, 1990. The workshop was attended by 62 scientists from seven countries with interests in geothermal reservoir engineering, nuclear waste isolation, unsaturated zone hydrology, environmental problems, and laboratory and field experimentation. The meeting featured 21 technical presentations, extended abstracts of which are reproduced in the present volume in unedited form. Simulator applications included processes on a broad range of space scales, from centimeters to kilometers, with transient times from seconds to geologic time scales. A number of code enhancements were reported that increased execution speeds for large 3-D problems by factors of order 20, reduced memory requirements, and improved user-friendliness. The workshop closed with an open discussion session that focussed on future needs and means for interaction in the TOUGH user community. Input from participants was gathered by means of a questionnaire that is reproduced in the appendix. 171 refs., 91 figs., 16 tabs.

This report contain viewgraphs of papers from the following sessions: plasma facing components issues for future machines; recent PMI results from several tokamaks; high heat flux technology; plasma facing components design and applications; plasma facing component materials and irradiation damage; boundary layer plasma; plasma disruptions; conditioning and tritium; and erosion/redeposition.

This report contains 40 papers that were presented at the Joint IAEA/CSNI Specialists` Meeting Fracture Mechanics Verification by Large-Scale Testing held at the Pollard Auditorium, Oak Ridge, Tennessee, during the week of October 26--29, 1992. The papers are printed in the order of their presentation in each session and describe recent large-scale fracture (brittle and/or ductile) experiments, analyses of these experiments, and comparisons between predictions and experimental results. The goal of the meeting was to allow international experts to examine the fracture behavior of various materials and structures under conditions relevant to nuclear reactor components and operating environments. The emphasis was on the ability of various fracture models and analysis methods to predict the wide range of experimental data now available. The individual papers have been cataloged separately.