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A number of equipment revisions have been recommended by the Engineering Department for conversion of Recuplex to a manufacturing facility. These revisions include three items affecting the critical mass safety of the solvent extraction system: replacement of the bottom disengagement section of the H-3 stripping column with an always safe unit; replacement of the H-9 and H-10 intercolumn, organic phase surge tanks with always safe tanks; and replacement of the colorimetric plutonium monitors in the aqueous and organic raffinate streams with units insensitive to stream contaminants. This memorandum is intended to clarify the needs for these equipment revisions in achieving a safe and flexible operating system and to indicate the relative effects of revising each of the various equipment pieces separately. The general bases for the present criticality control measures in the solvent extraction system are reviewed briefly prior to discussion of the individual revisions.

A previous report described the conceptual design of a plutonium producing reactor that may be characterized as follows: Power output (2000 MW); cooling - (natural convection of light water through the reactor, up through a draft tube to an evaporative cooling pond, then back to the reactor, and fuel (400 to 500 tons of uranium enriched to 1.2% U-235). Because this reactor would be cooled by the natural convection of light water, it is believed that the construction costs would be significantly less than for a Savannah or Hanford type reactor. Such expensive items as water treatment and water pumping facilities would be eliminated entirely. The inventory of 500 tons of slightly enriched uranium, however, is an unattractive feature. It represents not only a large dollar investment but also makes the reactor less attractive for construction during periods of national emergency because of the almost certain scarcity of even slightly enriched uranium at that time. The Atomic Energy Commission asked that the design be reviewed with the objective of reducing the inventory of uranium, The results of this review are given in this report.

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The leakage of electricity aoross a vacuum space in an electrostatic generator which employs a mixture of Sr/sup 90/ and Y/sup 90/ as the source of charging current was investigated. The vacuum is obtained by means of an oil pump. The leakage was shown to consist of a flow of positive and negative particles between the anode and the cathode. The positive particles were found to be primarily organic ions produced in a layer of oil on the surface of the anode. The negative particles were shown to be mostly electrons. Yields of secondary negative particles and secondary positive particles produced by average positive particles in the energy range from 50 to 200 kev were measured. Yields were found to be dependent on the nature of the target material as well as on the energy of the incident ion. A mass spectrometer was employed to study the nature of the positive ions. Most of these were charged fragments of organic molecules. Neutral particles were attributed to dissociation of a portion of positive ions during their flight from the anode to cathode. Electrons, most of which originate at the beta source, are presumed to be the agent for positive ion production. …

The design, selection, and calculation of the Army Package Power Reactor shielding are described. The APPR-1, a prototype of a package reactor for remote locations, has a primary shield of Fe and water. This shield has been adopted to permit fast erection and to provide low transported weight. Economically, including transportation cost, the Fe--water shield is better thnn a Pb--water shield and is competitive with a concrete shield for a remote site. Because of its location at Fort Belvoir, Va., the shielding requirements for the APPR-1 are considerably more stringent than those for a reactor at a remote base. Since the secondary shielding which surrounds the entire primary system must provide protection for personnel at any location outside the vapor container, concrete is provided for this need. (auth)

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Judging from the condition of the tube walls, this heat exchanger was close to failure. The depth of intergranular attack on the inner NaK surface (0.003 in.) and the depth of subsurface voids on the fuel side (0.007 in.) were more than half the wall thickness and these measurements were only from a few scattered specimens and on one plane per specimen. The grain size was much larger in the hot end than in the cold end of the heat exchanger. This increased grain size in the hot end could be attributed to the absence of precipitate and greater triaxial stresses due to thermal expansion and a thermal differential across the tube wall. Also, the strain anneal effect due to the thermal cycling during operation at a specific temperature would accelerate grain growth. These stress conditions and the resulting change in microstructures are directly related to the operating temperature at the hot end. The greater depth of corrosion at the hot end could also be due to a greater stressed condition or a corrosion fatigue. Mass transfer was present where the NaK entered the heat exchanger, but this deposition was influenced greatly by flow against the tube walls. The maximum …

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Modifications are described in the nuclear instrumentation system of the Shippingport Pressurized Water Reactor designed to monitor neutron flux level from source to 150% of reactor designed full power output, to compute the rate of change of the neutron flux level for indication and control, and to provide level and rate of change of level signals for reactor shutdown to prevent reactor damage. (C.H.)

Pilot plant experiments are described in which trichloroethylene was used for the reduction of uranium hexafluoride to uranium tetrafluoride. After unsatisfactory preliminary results with liquid phase reduction, satisfactory results were obtained with a vapor phase reduction system. It was found that vapor phase reduction at approximately 450 deg F, produced a low density product which contained only small quantities of uranium(VI); sintering the uranium tetrafluoride in a hydrogen fluoride atmosphere increased the product density to approximately 3 g/cc. The reduction was essentially complete, and the effluent gas contained less than 1 ppm of uranium hexafluoride. The purity of the uranium tetrafluoride produced was equivalent to that of the uranium hexafluoride used as feed. A complete discussion is given of the operation of the various parts of the system. (auth)