We have investigated the role of an isomeric state and its coupling to the ground state (g.s.) via photons and neutron inelastic scattering in a stellar environment by making detailed photonuclear and neutron cross-section calculations for /sup 176/Lu and /sup 210/Bi. In the case of /sup 176/Lu, the g.s. would function as an excellent galactic slow- (s-) process chronometer were it not for the 3.7-h isomer at 123 keV. Our calculations predicted much larger photon cross sections for production of the isomer, as well as a lower threshold, than had been assumed based on earlier measurements. These two factors combine to indicate that an enormous correction, a factor of 10/sup 7/, must be applied to shorten the current estimate of the half-life against photoexcitation of /sup 176/Lu as a function of temperature. This severely limits the use of /sup 176/Lu as a stellar chronometer and indicates a significantly lower temperature at which the two states reach thermal equilibrium. For /sup 210/Bi, our preliminary calculations of the production and destruction of the 3 /times/ 10/sup 6/ y isomeric state by neutrons and photons suggest that the /sup 210/Bi isomer may not be destroyed by photons as rapidly as assumed in certain …

This review discusses the current situation for opacities at the solar center, the solar surface, and for the few million kelvin temperatures that occur below the convection zone. The solar center conditions are important because they are crucial for the neutrino production, which continues to be predicted about 4 times that observed. The main extinction effects there are free-free photon absorption in the electric fields of the hydrogen, helium and the CNO atoms, free electron scattering of photons, and the bound-free and bound-bound absorption of photons by iron atoms with two electrons in the 1s bound level. An assumption that the iron is condensed-out below the convection zone, and the opacity in the central regions is thereby reduced, results in about a 25 percent reduction in the central opacity but only a 5 percent reduction at the base of the convection zone. Furthermore, the p-mode solar oscillations are changed with this assumption, and do not fit the observed ones as well as for standard models. A discussion of the large effective opacity reduction by weakly interacting massive particles also results in poor agreement with observed p-mode oscillation frequencies. The much larger opacities for the solar surface layers from the Los …

The Rocky Flats Plant is introducing the use of dicesium hexachloroplutonate (DCHP) into the Molten Salt Extraction Process (MSE). DCHP (Cs/sub 2/PuCl/sub 6/) extracts americium from molten plutonium metal into a molten calcium chloride matrix. The DCHP is produced by precipitating plutonium (IV) from hydrochloric acid with cesium chloride. Before production of the DCHP began, we performed a pilot-scale test to determine yields, track impurities, and test filtrate recovery for the proposed process. In the course of this study, we determined that impure plutonium oxide (0.80 g/g) dissolved in concentrated HCl is an acceptable source of plutonium for the DCHP. We also determined that dissolved oxide and chloride anion exchange eluate can be mixed for DCHP preparation. We found that DCHP yields average 92-95% at 8M total chloride and are independent of sparging rate and time. Furthermore, we found that drying at 150/degree/C for 5 hr gives <0.1% water in the DCHP only if it is preceeded by extensive air drying. Finally, we proved the efficiency of chloride anion exchange for the recovery of above-discard plutonium from the filtrate. 11 refs., 1 fig., 11 tabs.

Induction linear accelerators (LIAs) are inherently capable of accelerating several thousand amperes of /approximately/ 50-ns duration pulses to > 100 MeV. In this paper we report progress and status in the areas of duty factor and stray power management. These technologies are vital if LIAs are to attain high average power operation. 13 figs.

My remarks are concerned with employing the Compact Torus magnetic field configuration to produce fusion energy. In particular, I would like to consider high energy density regimes where the pressures generated extend well beyond the strength of materials. Under such conditions, where nearby walls are vaporized and pushed aside each shot, the technological constraints are very different from usual magnetic fusion and may admit opportunities for an improved fusion reactor design. 5 refs., 3 figs.

Constant extension rate tests (CERT) were run on ten irradiated specimens in continuation of a study of environmental effects on intergranular stress corrosion cracking of type 304 stainless steel. Specimens of both furnace sensitized and annealed material were irradiated to fluences of 1 to 2 {times} 10{sup 21} neutrons (E {ge} 0.1 Mev) per square centimeter at a temperature of {approximately}150{degree}C in a reflector position of the High Flux Isoptope Reactor at ORNL. CERT test conditions duplicated conditions for testing of non-irradiated specimens. The time-to-failure for the sensitized and irradiated specimens showed the same pattern of dependence on test variables as the non-irradiated specimens in an associated study. The annealed and irradiated specimens showed no evidence of irradiation assisted stress corrosion cracking.

Organic aerogels are a special type of low density foam produced from the supercritical drying of resorcinol-formaldehyde (RF) gels. These aerogels have continuous porosity, ultrafine cell/pore sizes (&lt;1000 {angstrom}), and a microstructure composed of interconnected colloidal-like particles with diameters ranging from 30-175 {angstrom}. The particle size, surface area, density, and mechanical properties of the aerogels are largely determined by the catalysts concentration used in the sol-gel polymerization. In order to gain some insight into the crosslinks between RF particles, aerogels were labeled with C-13 formaldehyde at various times in the polymerization. CPMAS and IRCP techniques were used to correlate the relaxation behavior of the C-13 enriched aerogels with their different microstructures. 9 refs., 1 fig., 2 tabs.

Two uses of the Perkin-Elmer (PE) robotic system will be presented. In the first, a PE robot functions as an automatic sample changer for up to five low energy photon spectrometry (LEPS) detectors operated with a Nuclear Data ND 6700 system. The entire system, including the robot, is controlled by an IBM PC-AT using software written in compiled BASIC. Problems associated with the development of the system and modifications to the robot will be presented. In the second, an evaluation study was performed to assess the abilities of the PE robotic system for performing complex analytical sample preparation procedures. For this study, a robotic system based upon the PE robot and auxiliary devices was constructed and programmed to perform the preparation of final product samples (UO{sub 3}) for accountability and impurity specification analyses. These procedures require sample dissolution, dilution, and liquid-liquid extraction steps. The results of an in-depth evaluation of all system components will be presented.

Constant extension rate tests (CERT) were run on ten irradiated specimens in continuation of a study of environmental effects on intergranular stress corrosion cracking of type 304 stainless steel. Specimens of both furnace sensitized and annealed material were irradiated to fluences of 1 to 2 {times} 10{sup 21} neutrons (E {ge} 0.1 Mev) per square centimeter at a temperature of {approximately}150{degree}C in a reflector position of the High Flux Isoptope Reactor at ORNL. CERT test conditions duplicated conditions for testing of non-irradiated specimens. The time-to-failure for the sensitized and irradiated specimens showed the same pattern of dependence on test variables as the non-irradiated specimens in an associated study. The annealed and irradiated specimens showed no evidence of irradiation assisted stress corrosion cracking.

Article evaluating the selectivity of compounds originally identified as inhibitors of poly(ADP-ribose) polymerase on members of the three classes of enzymes. The results suggest that micromolar levels of the benzamides in the culture medium should allow selective inhibition of poly(ADP-ribose) metabolism in intact cells. Furthermore, comparative quantitative inhibition studies should prove useful for assigning the biological effects of these inhibitors as an effect on either poly(ADP-ribose) or mono(ADP-ribose) metabolism.