Chemical processing, blanket material

In tlie PUREX process, the spent fuel and blanket materials are dissolved in nitric acid to form nitrates of plutonium and uranium. These are separated chemically from the other fission products, including the highly radioactive actinides, and then the two nitrates are separated into tv/o streams of partially purified plutonium and uranium. Additional processing will yield whatever purity of the two elements is desired. The process yields purified plutonium, purified uranium, and high-level wastes. See also Radioactive Wastes in the entry1 on Nuclear Power Technology. Because of the yield of purified plutonium, the PUREX process is most undesirable from a nuclear weapons proliferation standpoint,... 

Fuel composition may change from uranium to plutonium, and cladding from aluminum to zirconium to stainless steel. In some cases blankets, moderators, and coolants must be processed, and these will introduce thorium, beryllium, NaK, and bismuth to the chemical process. These changes in materials will present new chemical and corrosion problems in waste treatment processes and waste storage procedures. 

Fire hazards are minimized by minimum inventories of chemicals. Control or miniini/e ignition sources, provide a confining area, reduce the temperature of the material as much iis possible, blanket the material to eliminate air contact. Have available fire protection equipment breathing apparatus, and protective clothing for the fire fighters. Use several hour fire walls to prevent the spread of fire to other process areas. 

This paper describes a process for activating polyimide surfaces for electroless metal plating. A thin surface region of a polyimide film can be electro-chemically reduced when contacted with certain reducing agent solutions. The electroactivity of polyimides is used to mediate electron transfer for depositing catalytic metal (e.g., Pd, Pt, Ni, Cu) seeds onto the polymer surface. The proposed metal deposition mechanism presented is based on results obtained from cyclic voltammetric, UV-visible, and Rutherford backscattering analysis of reduced and metallized polyimide films. This process allows blanket and full-additive metallization of polymeric materials for electronic device fabrication. 

The chemical vapor deposition of tungsten silicide (WSix) is also covered in this book in chapter IX. This material was included since the chemistry and equipment are so similar to blanket tungsten. Additionally, it allowed the coverage of the SiH2Cl2 based tungsten silicide process which is relatively new today. 

Thus, a mineral (part of a rock) that formed and was at equilibrium under conditions of elevated temperatiue and pressure is imstable at eeirth surface conditions. The addic water, possibly aided by temperature fluctuations, attacks the mineral and a series of chemical reactions ensue producing a series of new minerals which are at equilibrium under the new conditions. If there is suffident time, then ultimately the end of the search for thermodynamic equilibrium produces clay minerals with lesser quantities of other colloidal materials. This is the process known as weathering and is the major source of sediments and soils at the earth s surface on the continents and blanketing... 

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