Investigation to evaluate some of the designs, techniques, and methods for fabrication of a root pass.

From introduction: "The development and demonstration of the natural uranium reprocessed plutonium cycle in power reactors is an important phase of the peaceful applications of nuclear energy."

The stability of fluorothene (polytrifluorochloroethylene, Kel-F) to gamma radiation has been investigated to estimate the probable life expectancy of fluorothene equipment exposed to Purex process solutions. Samples of fluorothene were exposed to total gamma radiation dosages up to 10 degree R. The results of these tests substantiate the findings reported by Sisman and Bopp in their compilation of data on the affects of radiation on plastics.

A preliminary report has shown the potential importance of organic reactor coolants to Hanford technology. The salient points are complete avoidance of corrosion problems and accomplishment of DPR performance with low pressure technique. The recommendation of the report that loop tests be made at Hanford is to be acted upon by Recirculation Technology Unit as soon as organic coolant material is received. To insure starting this experimental work fully abreast of the information available, a trip to sites working with organic coolants was made. Specifically, data were sought on practical details of design for handling organic coolants, heat transfer and fouling characteristics, corrosion of materials, and hazards of handling organics.

Contemplated higher tube power for future reactor operation will probably require a fuel element jacketing material more corrosion resistant than presently available aluminum alloys. Zirconium and its alloys are generally regarded as the most promising jacketing candidates for high temperature operation, particularly for exposures of long duration. In order to obtain assembly, welding, and corrosion data, twenty Al-Si bonded and twenty unbonded Zircaloy fuel elements were prepared for KER loop testing. This report describes the technique developed to weld Zircaloy jacketed fuel elements and presents the results of end closure corrosion testing and metallographic examination.

The dependence of the resonance integral for thorium upon geometry and thorium temperature has been determined through reactivity coefficient measurements performed in the Hanford Test Pile. The geometry dependence was investigated using thorium cylinders of various diameters in the form of solid elements and shells. The temperature dependence (Doppler broadening) was studied by heating thorium elements and permitting them to cool while observing the change in pile reactivity.

Description of Invention: Chloride-induced corrosion is a serious problem in the Purex acid recovery operation and in the evaporative concentration of process streams and waste solutions. In the case of Purex acid recovery, it has been shown that trace chloride will volatilize with the nitric acid and reflux in the acid fractionator, thus causing especially severe corrosion at that point. These traces of chloride may enter the process form several sources, i.e., as an impurity in the technical grade chemicals used in making up the various aqueous process streams, by hydrolysis or radiation decomposition of carbon tetrachloride (a promising diluent for tributyl phosphate), or by incomplete removal of the hydrochloric acid employed in some flowsheets for effecting the dissolution of certain difficulty soluble nuclear reactor fuel elements.

Neutron attenuation in the old pile shields is dependent more and more on the slowing down characteristics of the iron as the hydrogen is baked out of the masonite. For neutrons above 1 or 2 Mev, iron does a good job by inelastic scattering. However, below this energy attenuation can be done only by the gradual moderation by elastic scattering to thermal energies with subsequent capture in the iron. Since iron is heavy and thus a poor moderator, there is a good possibility that many neutrons of intermediate energy will leak out of a burned out shield. Also, iron has a large dip in its cross section at 25 Kev which might allow a large burst of neutrons at this energy to leak out. Measurements using a lucite moderator with gold foil detectors indicate a large leakage of neutrons of intermediate energy, but interpretation of these measurements is difficult. These considerations prompted an attempt to get a rough idea of the energy distribution of the leakage neutrons through pure iron using a simple qualitative theory.

In connection with studies of the chemical reactivity of PuO_2 to hydrofluorination, samples were examined by X-ray diffraction for crystallite size and perfection. The PuO_2 was formed by thermal decomposition of the oralate. The reactivity of this oxide, as well as that of other solid oxides is affected by the conditions of preparation. Besides the obvious influence of surface, including lattice strain and other structural irregularities in the particles. Each particle is composed of a number of crystallites. The extent of crystallites size and perfection will be indicated by the width of a diffracted X-ray beam. Since separation of these two caus4es would require a detailed analysis, the observed broadening was interpreted on the assumption of crystallite size effects alone. However, the variable factor in preparation method was temperature, and it is to be expected that crystallite growth with annealing will occur in part at the expense of energy stored in nonequilibrium states of the crystal, i.e., imperfections. The objectives of this study were to establish a convenient method for determination of PuO_2 crystallite size and to obtain estimates of the crystallite sizes of seven given samples.