The method under development for the production of semiconductor grade silicon is based on the zinc vapor reduction of silicon tetrachloride in a fluidized bed of seed particles. Construction of the PDU was completed during the report period, the fluidized-bed reactor was coated internally with silicon/SiC, and the operation of several systems was checked out. However, problems with the zinc feed system, unrelated to its basic operability, delayed introduction of zinc vapor to the PDU. At the end of the report period, the zinc feed system stood ready for tests of the control of zinc vapor feed rate by regulation of r.f. induction heating directly coupled to the liquid zinc. A study of the zinc distribution in miniplant silicon products containing zinc at the 300 and 3000 ppM levels suggests that the occlusion of zinc is caused by zinc mist entrained from the vaporizer, and it should be possible to drive the level to below 300 ppM by proper equipment design and process control.

The development of stable, efficient, electrochemical photovoltaic cells based on silicon and gallium arsenide in non-aqueous electrolyte systems is being investigated. The effect of surface condition of silicon electrodes on electrochemical and physical characteristics has been studied. An electrode-supporting electrolyte interaction in acetonitrile has been identified which leads to etching of the surface. Improved performance can result, which has practical significance. Gallium arsenide electrodes have been electrochemically characterized in cells containing propylene carbonate with a ferrocene/ferricenium redox additive. Degradation of the ferricenium salt under illumination has been investigated. Other redox couples studied to date have not given promising results. Long-term stability experiments have been deferred while a better understanding of electrode behavior is being obtained.

The results of work performed from July 1, 1979 through September 30, 1979 on the Advanced Gas-Cooled Nuclear Reactor Materials Evaluation and Development Program are presented. The objectives of this program are to evaluate candidate alloys for Very High Temperature Reactor (VHTR) Nuclear Process Heat (NPH) and Direct Cycle Helium Turbine (DCHT) applications, in terms of the effect of simulated reactor primary coolant (helium containing small amounts of various other gases), high temperatures, and long time exposures, on the mechanical properties and structural and surface stability of selected candidate alloys. A second objective is to select and recommend materials for future test facilities and more extensive qualification programs. Work covered in this report includes the activities associated with the status of the simulated reactor helium supply system, testing equipment, and gas chemistry analysis instrumentation and equipment. The status of the data management system is presented. In addition, the progress in the screening test program is described.

A weekly publication, the Texas Register serves as the journal of state agency rulemaking for Texas. Information published in the Texas Register includes proposed, adopted, withdrawn and emergency rule actions, notices of state agency review of agency rules, governor's appointments, attorney general opinions, and miscellaneous documents such as requests for proposals. After adoption, these rulemaking actions are codified into the Texas Administrative Code.

The purpose of this contract is to provide the Coal and Electric Power Analysis Division, EIA, with a revised and fully documented Resource Allocation and Mine Costing (RAMC) model to be used in developing coal supply curves for use in the Mid-range Energy Forecasting System and the National Coal Model. The project is structured in three phases, as follows: establish conceptual underpinnings of revised supply curve methodology; revise mine costing methodology; and revise resource allocation methodology. The first three tasks in Phase I were to review and critique the current RAMC approach, review and critique the NUS deep mine and the Fluor Utah surface mine costing methodologies, and to propose revisions to the current approach. This Interim Report documents our findings under these three tasks. Our review of the current RAMC concludes that the resource allocation methodology is reasonable; however, the mine costing methodology has a number of deficiencies. Hence, Section 5 presents a number of alternative approaches for implementing an improved costing methodology in the RAMC model. Although the resource allocation approach is reasonable, the data used to drive the model need to be improved. The Appendices discuss a number of these data issues, affecting both mine costing and …