Objective is to determine the fracture toughness of A533B-1 steel by computer modeling Charpy V-notch tests. A computer model of ductile fracture was developed that predicts fracture initiation. The model contains a set of material-dependent parameters obtained by computer simulations of small specimen tests. The computer calculations give detailed stress and strain histories up to the time of fracture, which are used to determine the model parameter values. The calibrated fracture model, that correctly predicts fracture initiation (and initiation energy) in the Charpy specimen, may then be used to simulate tests of accepted fracture-toughness specimens and hence obtain fracture toughness. The model parameters were calibrated to predict fracture in four different test specimens: two different notched-tension specimens, a simple tension specimen, and a precracked compact-tension specimen. The model was then used in a computer simulation of the Charpy V-notch specimen to initiate and advance a flat fracture. Results were compared with interrupted Charpy tests. Calibration of the model for two additional heat treatments of A533B-1 steel is in progress.

The Environmental Science Division at Lawrence Livermore Laboratory has in use a system of absolute Instrumental Neutron Activation Analysis (INAA). Basically, absolute INAA is dependent upon the absolute measurement of the disintegration rates of the nuclides produced by neutron capture. From such disintegration rate data, the amount of the target element present in the irradiated sample is calculated by dividing the observed disintegration rate for each nuclide by the expected value for the disintegration rate per microgram of the target element that produced the nuclide. In absolute INAA, the expected value for disintegration rate per microgram is calculated from nuclear parameters and from measured values of both thermal and epithermal neutron fluxes which were present during irradiation. Absolute INAA does not depend on the concurrent irradiation of elemental standards but does depend on the values for thermal and epithermal neutron capture cross-sections for the target nuclides. A description of the analytical method is presented.

A survey to identify numerical control postprocessors available at Department of Energy facilities is reported. The data are presented in the body of the report under the postprocessor identification. Information supplied includes the vendor name and address, the N/C and postprocessor languages, the machine tools and control unit supported, the computers used, and the identification of the DOE installation. The body of the report is followed by five indexes permitting users to refer to the postprocessor data by product number, DOE installation, machine tool, control unit, or computer. (RWR)

The technical progress reported in the current quarterly report can be divided into five task areas. They are as follows: (1) Spectroscopic Analysis and Characterization of the (SiF/sub 2/)/sub x/ Polymer and Si/sub x/F/sub y/ Homologues. Preliminary analysis utilizing N.M.R., T.G.A., D.S.C. and Mass Spec. are consistent with both the (SiF/sub 2/)/sub x/ polymer and Si/sub x/F/sub y/ homologues being nearly identical in chemical composition (mainly SiF/sub 2/ group in long chain polymers or cyclic homologues) and thermal stability. (2) Experiments Involving Si/sub x/F/sub y/ Homologue Conversion Chemical Vapor Deposition of Silicon. Results from these experiments demonstrate that a bed of heated (850/sup 0/C) silicon chunks is an effective way to convert the homologues into silicon in high yield. (3) Demonstration Runs on the Near-Continuous Apparatus. The near-continuous apparatus has been operated at rates greater than or equal to 25 gm/hr in two multihour series of runs for silicon production and parameter optimization. In the most recent series, the apparatus was operated for 8 hours in a near-continuous fashion during which 155 grams of silicon was purified and a weighed silicon mass balance revealed approximately 100 percent of the silicon accounted for. (4) Economic Analysis. An economic analysis incorporating a …