The influence of dissolved oxygen and hydrogen and dilute sulfuric acid in 289/sup 0/C water on the stress-corrosion-cracking susceptibility of lightly and moderately sensitized Type 304 stainless steel was determined in constant-extension-rate tensile (CERT) tests. The CERT parameters and the fracture surface morphologies were correlated with the concentrations of dissolved oxygen and sulfate, and the electrochemical potentials of platinum and Type 304 stainless steel electrodes in simulated boiling-water reactor (BWR) environments. A particularly high susceptibility to intergranular cracking was found for the steel in the lightly sensitized condition at oxygen concentrations between approx. 0.05 and 0.2 ppM under slightly acidic conditions (pH approx. 6.0 at 25/sup 0/C), which may, in part, account for the pervasive nature of intergranular cracking in BWR piping systems. Scanning-transmission electron microscopy analyses revealed significant differences between samples in the lightly and the moderately sensitized condition with respect to the width, but not the depth, of the chromium-depleted region at the grain boundaries. The addition of 0.5 ppM hydrogen to the water had only a small mitigating effect on intergranular cracking in water containing oxygen and sulfuric acid at low concentrations; however, oxygen suppression to less than or equal to 0.05 ppM in the reactor-coolant water, …

This paper analyzes the geometrically nonlinear bending and collapse behavior of an elastic, simply supported cylindrical shell subjected to an inward-directed point load applied at midlength. The large displacement analysis results for this thin (R/t = 638) poked cylinder were obtained from the STAGSC-1 finite element computer program. STAGSC-1 results are also presented for two other point-loaded shell problems: a pinched cylinder (R/t = 100), and a venetian blind (R/t = 250).

We report on the use of a 5.8 GHz microwave applicator to treat choroidal melanoma (Greene) in rabbits. The physical requirements needed to treat these intraocular tumors are quite different from those encountered elsewhere in the body. From a trans-scleral approach the penetration needed is minimal (5 to 10 mm.). The fibrous sclera is the only structure between the heat source and the tumor. The sclera has a relatively low water content when compared to tumor. This fact in addition to the frequency dependent interactions of tissue and electromagnetic radiation, results in an advantage to the use of the 5.8 GHz microwave device in treating intraocular malignancies.

The W-2 SLSF (Sodium Loop Safety Facility) experiment was an instrumented in-reactor test performed to characterize the failure response of full-length, preconditioned LMFBR prototypic fuel pins to slow transient overpower (TOP) conditions. Although the test results were expected to confirm analytical predictions of upper level failure and fuel expulsion, an axial midplane failure was experienced. Extensive post-test analyses were conducted to understand all of the unexpected behavior in the experiment. (1) The initial post-test effort focused on the temperature oscillations recorded by the 54 thermocouples used in the experiment. In order to synthesize the extensive data records and identify patterns of behavior in the data records, a computer-generated film was used to present the temperature data recorded during the experiment.

Optical second-harmonic generation (SHG) is sensitive enough to respond to a submonolayer of surface atoms or molecules. It can therefore be used to probe surfaces or interfaces between two centrosymmetric media. The surface-specific nature of this optical method offers some advantages. We have demonstrated in recent experiments that resonant SHG can allow us to obtain spectroscopic data of submonolayers of adsorbed molecules on a surface. The signal was so strong that less than one tenth of a monolayer of dye molecules could be easily detected. The method can be applied to molecules adsorbed at an interface between two dense media such as a liquid/solid interface. Then, using SHG, adsorption isotherms of adsorbates on substrates can be measured. One is often interested in how large the bulk contribution to SHG is in comparison with the surface contribution. Second-order nonlinear optical processes are forbidden in a medium with inversion symmetry only in the electric-dipole approximation. Could SGH from electric-quadrupole and magnetic-dipole contributions in the bulk be so strong as to mask out the electric-dipole contribution from the surface. We have found that the SH signal from a centrosymmetric substrate can be changed appreciably by the adsorption of a monolayer. This clearly indicates …

The requirements to be met by Pockels cell drivers for incorporation into the Novette and Nova Laser systems are presented, and critical aspects of the specification examined. A high-performance pulse generator has been developed to meet these requirements using new thyratron technology from the English Electric Valve Co. Ltd. Two closely related versions have been built; a 10KV output unit with 9 nsec risetime into five parallel 50-ohm loads and a faster 5KV output driver with 3.5 nsec risetime into a single 50-ohm load. The design approach for optimizing performance, using the new tubes in relation to the LLNL specification is described, including the techniques used for control of electromagnetic interference.

A breeding ratio of at least 1.2 was a design goal for CRBRP. The value for the initial core (using plutonium with 11% /sup 240/Pu) calculated with ENDF/B-IV data is 1.27. Engineering mock-up studies for CRBRP were made in ZPPR-11. Analysis of ZPPR-11 using ENDF/B-IV data showed consistent underprediction of K/sub eff/ by about 1.5% and overpredictions of the /sup 238/U capture to /sup 239/Pu fission ratio (C8/F9) between 5% and 8%. These results are typical for all LMFBR critical assemblies at ANL. The following approach was used to determine the breeding ratio: sensitivity analysis of a range of fast reactor benchmarks and a fit to the experimental data by data adjustment; tests of the adjusted data against experiments in ZPPR-11; calculations for CRBRP with ENDF/B-IV data and the adjusted data to predict the breeding ratio bias; and estimates of k/sub eff/ and breeding ratio uncertainties using data sensitivities for CRBRP.

New switching power supplies were designed for the 10 mm laser amplifiers in the Nova Master Oscillator Room. The flashlamp supply must be repratable. Therefore, we designed a constant current, linearly charging power supply. Since it is a capacitor, the load varies throughout the charge cycle. At first the load is great, and di/dt of load current is at a maximum. As the capacitor charges the initial conditions for each cycle change, the power supply in effect sees a smaller capacitance, and di/dt decreases. We need a way of gradually increasing the on-time of the current pulses so that the transistors in the power bridge are turned off when they reach their maximum peak current. The normal current sense response of the control chip is not fast enough to be useful for our application. The deadtime, or the time that all the bridge transistors are turned off, is fixed so that as the pulse width varies so does the period. We end up with a constant peak current, switching power supply whose frequency varies from 50 khz to 20 khz. Finally, an overcurrent latch protects the transistors from bridge or transformer faults. The circuit is described and results are shown.

Increasing effort is being put into engineering designs of reactors and reactor-like magnetic confinement experiments. A central question concerns the methods of heating, fueling, and maintaining the plasmas, functions that primarily are now performed by neutral beams. Planning in the USA does not include the use of neutral beams on tokamaks in the 1990's and beyond. Tandem mirrors, however, will use energetic beams (sloshing ion beams) in the end plugs to produce electrostatic potentials that will confine plasma ions. These systems will be based on the production, acceleration, transport, and neutralization of negative hydrogen-ion (D/sup -/), multiampere beams with energies of 200-to 500-keV. In addition, lower-energy D and T beams may be used. These systems must operate steady state, with high reliability, and be compatible with radiation from a D-T burning plasma.

We have measured the production cross section and momentum distribution of K/sup -/ produced at 0/sup 0/ in /sup 28/Si + /sup 28/Si collisions at an energy of 2.1 GeV/nucleon. The K/sup -/ spectrum is approximately exponential. The large yield in the subthreshold production of K/sup -/ that we observe corresponds to a production rate of 1K/sup -/ per 50 collisions at impact parameters less than 1f. Productions mechanisms involving collective effects and thermal equilibration are discussed.

Investigation of accelerator breeders at Brookhaven National Laboratory indicate that the AB-LWR fuel cycle is economically competitive with the LMFBR fuel cycle. The same can be said about the accelerator breeder-High Temperature Gas Reactor symbiosis. This system appears to be very competitive with the added real advantage of superior safety and proliferation resistance. This discussion would be incomplete if the real competitor to accelerator breeding was not mentioned, namely Fusion Hybrid Breeding (FHB). Fusion Hybrid Breeding is a nearer option than pure fusion, as the breakeven Q value requirements are much more modest. Fusion Hybrid Breeding, if successful and practical, has the potential for highly efficient fissile fuel breeding, leading to cheaper fuel. The system, however, has yet to be demonstrated scientifically and to be shown commercially feasible. This is in contrast with the AB system which is an extension of proven, state-of-the-art technology with implementation possible within twenty years. 25 references, 4 figures, 5 tables.

We perform an analytic study of some quantities relevant to the plasma beat-wave accelerator (PBWA) concept. We obtain analytic expressions for the plasma frequency, longitudinal electron velocity, plasma density and longitudinal plasma electric field of a nonlinear longitudinal electron plasma oscillation with amplitude less than the wave-breaking limit and phase velocity approaching the speed of light. We also estimate the luminosity of a single-pass e/sup +/e/sup -/ linear PBWA collider assuming the energy and collision beamstrahlung are fixed parameters.

The Experimental Breeder Reactor No. 2 (EBR-II) has been modeled using a recently developed special purpose block oriented simulation language, the Dynamic Simulator for Nuclear Power Plants (DSNP). The purpose of the work was to develop and verify the code and use it to support the Operational Reliability Test Program at EBR-II. Designed to be set up directly from block diagrams of the reactor system, DSNP allows easy interchange of modules which simulate individual components of the plant with differing levels of complexity.

The objective is to investigate whether existing technology might be extrapolated to provide the conceptual framework for a major hadron-hadron collider facility for high energy physics experimentation for the remainder of this century. One contribution to this large effort is to formalize the methods and mathematical tools necessary. In this report, the main purpose is to introduce the student to basic design procedures. From these follow the fundamental characteristics of the facility: its performance capability, its size, and the nature and operating requirements on the accelerator components, and with this knowledge, we can determine the technology and resources needed to build the new facility.

The paper discusses the development program in magnetic switching which was aimed at solving the rep-rate and reliability limitations of the ATA spark gaps. The end result has been a prototype physically very similar to the present Advanced Test Accelerator (ATA) pulse power unit but vastly superior in performance. This prototype, which is easily adaptable to the existing systems, has achieved a burst rep-rate of 20 kHz and an output voltage of 500 kV. A one-on-one substitution of the existing pulse power module would result in a 100 MeV accelerator. Furthermore, the high efficiency of the magnetic pulse compression stages has allowed CW operation of the prototype at one kilohertz opening up other applications for the pulse power. Performance and design details will be described.

There are two significantly different mechanisms proposed for the origin of the optogalvanic effect in a hollow-cathode discharge: (1) laser excitation of atoms to higher electronic states leads to an increased cross section for electron impact ionization, with the result that the excited atom becomes ionized and the conductivity of the discharge increases; and (2) laser excitation of atoms to higher electronic states perturbs the equilibrium established between the electron temperature and the atomic excitation temperature. Superelastic collisions between the electrons and the laser-excited atoms restore the equilibrium, with the excess energy ending up in an increased electron temperature and therefore an increased conductivity of the discharge. Both mechanisms undoubtedly proceed simultaneously and what needs to be determined is their relative importance at different discharge conditions and different excitation conditions. This is important because laser isotope enrichment schemes have been proposed using selective excitation in a hollow-cathode discharge. In order for these schemes to work, (1) must be the predominant mechanism. We have measured the optogalvanic signal, concentration of uranium atoms, impedance of the discharge, and electron temperature as a function of the discharge current in a neon-filled uranium hollow-cathode discharge. The hollow cathode operating characteristics are used as input …

During lower-hybrid heating in low-density-tokamak discharges, a nonMaxwellian tail of high-energy electrons is formed. This tail carries the plasma current. Utilizing the fact that relativistic electrons emit bremsstrahlung predominantly in the forward direction, we investigate the shape of the electron distribution by measuring the dependence of the x-ray emission on the angle between the magnetic field and the line of sight. The experimental data indicate that the distribution function is predominantly peaked in the forward direction, although a small fraction of the electrons is in the backward cone. The energy dependence of the x-ray spectra is consistent with that of a velocity distribution which has a plateau extending out to several hundred kiloelectron volts. Radial profiles show that the hot electrons are located in the central plasma region and form a high-conductivity plasma with the current profile frozen in. The slope of the spectrum depends on the rf power and on the phasing of the waveguide grill, but not on the externally applied plasma voltage. Relaxation oscillations occur shortly after switching the rf off. They also appear during the rf for low rf power and at the high-density limit of the lower-hybrid current drive. The x-ray spectra confirm that parallel …

Some flow-cytometric and image analysis procedures under development for quantitative analysis of sperm morphology are reviewed. The results of flow-cytometric DNA-content measurements on sperm from radiation exposed mice are also summarized, the results related to the available cytological information, and their potential dosimetric sensitivity discussed. (ACR)

In the present work we study a facet of the plasma evolution, the formation and radiation of mesons at the surface of hog plasma. The surface meson radiation would play two important roles. First, it may carry some information about the pre-freezeout stage of the plasma evolution. Second, it causes a pressure decrease at the surface that works against the expansion. In the extreme, the plasma may extinct very rapidly by the surface meson radiation without collective expansion. It is very unclear how the incident quark degrees of freedom is converted into mesonic degrees of freedom and how the color confinement works in such a process. We have studied the problem by fully employing the chromoelectric flux tube model. We found that their parametrization is quite unsatisfactory and is actually incompatible with a dynamical description of color confinement. We briefly recapitulate our treatments and findings.

In this paper we describe several techniques for using lasers to study core-excited energy levels in the spectral region between 10 eV and 100 eV. We are particularly interested in levels that are metastable against autoionization and, in some cases, against both autoionization and radiation.

We have measured the charge fractions of uranium ions at energies of 962 MeV/amu and 430 MeV/amu passing through various thickness targets of mylar (Z approx. = 6.6), Cu (Z = 29) and Ta (Z = 73). From these we determine the equilibrium charge state distributions.

An investigation was conducted to study the nuclear design aspects of using very-low-activation materials, such as SiC, MgO, and aluminum for fusion-reactor first wall, blanket, and shield applications. In addition to the advantage of very-low radioactive inventory, it was found that the very-low-activation fusion reactor can also offer an adequate tritium-breeding ratio and substantial amount of blanket nuclear heating as a conventional-material-structured reactor does. The most-stringent design constraint found in a very-low-activation fusion reactor is the limited space available in the inboard region of a tokamak concept for shielding to protect the superconducting toroidal field coil. A reference design was developed which mitigates the constraint by adopting a removable tungsten shield design that retains the inboard dimensions and gives the same shield performance as the reference STARFIRE tokamak reactor design.

The availability of radioactive ion beams represents a major advance in the capbaility to attack important problems of basic and applied nuclear physics. For the first time we are able to study nuclear reactions on nuclides outside the valley of stability. These nuclides represent about 80% of particle-stable isotopes. Questions of nuclear reaction mechanisms, nuclear properties of bound and continuum states, and basic symmetries for these unstable nuclides can therefore be answered by direct mesurement rather than by speculation. The applications of radioactive ion beams are widespread and extensive. In astrophysical studies, nuclear reactions of radioactive ion beams are essential to understanding a wide range of problems in energy generation, nucleosynthesis, neutrino effects, and the implications of gamma-ray astrophysical measurements. In material studies, the implantation of radioactive ions has already seen important use. Well defined beams of these ions will greatly increase the specifity and sensititivity of this technology. Radioactive ion beams may also have significant applications in medical diagnostics and therapy. Finally, standard sources of beta and gamma radiation can be prepared with much greater precision than formerly available.

From both an experimental and an historical point of view it is particularly appropriate to summarize the development of nu/sub ..mu../e/sup -/ physics at this time. Historically, it was ten years ago last week that the announcement of the first nu/sub ..mu../e/sup -/ event was sent from Aachen to the other members of the Gargamelle Collaboration. The event, shown in Figure 2, is of a single electron identified via its characteristic bremsstrahlung and curvature. The significance of this event far exceeds its visual impact. With a background of less than .03 events, it became the first solid indication for the existence of the weak neutral current. On the experimental front, the investigation of the nu/sub ..mu../e interaction is about to enter a new phase, having graduated from experiments yielding 2 to 3 events to those which will be analyzing hundreds of events. With these high statistics experiments it should be possible to study the differential as well as the total crosssections of nu/sub ..mu../e and anti nu/sub ..mu../e scattering.