For many years effort has been directed toward the development of means for the practical utilization of the heat evolved from the radioactive decay of certain fission and irradiation products. Fission products, in view of their availability in the plentiful, high-level wastes resulting from the processing of irradiated, nuclear reactor fuels have been most intensively studied for applications where their heat of decay might be converted into useful energy such as electricity for the operations of certain devices in place of chemical batteries . In addition other materials having desired radioactive properties may be produced by neutron bombardment of readily available elements.

It is desirable that a reactor exhibit a self-regulating effect. If this were not true any disturbance to the reactor would result in a continual increase in the magnitude of the disturbance and the reactor would be unstable. In this investigation the reactor is considered to have two reactivity feed-backs: metal temperature and water temperature reactivity effects. These two variables through a metal temperature coefficient and water temperature coefficient determine not only the reactor stability but also determine many operational characteristics.

In support of the Plutonium Recycle Program at Hanford, the properties of PuO2 are being investigated. This paper reports sintering studies on PuO2 and PuO2-UO2 mixtures and solid solutions; melting studies on PuO2 and UO2; thermal expansion data to 1000 C; and irradiation data on PuO2-UO2 mixtures. The existence of a continuous series of solid solutions formed during sintering has been established for the system UO2-PuO2. A linear relation between lattice parameter and composition exists. Extensive sinterability data on the isomorphous compound UO2 and PuO2 and their intermediate compositions has been obtained. The effect on sintered density of temperature, time, and concentration for both physical additions of PuO2 and additions of UO2-PuO2 solid solutions to UO2 have been studied. Evaluation data are supported by microscopic examination and X-ray diffraction.

Relatively frequent agitator failures in HAPO Separations Plants have interfered with process continuity, contributed to process difficulties, and resulted in considerable maintenance expense. Predominantly the failures have been because of gear-reduction drive unit break-down or because of metallic fatigue and degeneration of the shaft-paddle assemblies. A simplified, slow-speed, direct drive agitator, previously described in HW-52755, proved to be quite durable and satisfactory during extended testing, operating without incident for over 10,000 hours. Subsequent operation of the agitator in the Redox Plant has been equally smooth. Total operating time (combined test and production use) is now in excess of 21,000 hours. Since the slow speed agitation principle has been adequately demonstrated at Redox and Purex canyon applications. This report describes the development and testing of such a "universal" agitator.

This is the sixth in a series of interim reports describing various phases of the study of fuel element rupture kinetics and mechanisms. Previous reports issued are: No. 1- Experimental Methods and Procedures, HW-61378, No. 2- Coextruded Rod Elements with Pinhole Defects, HW-61379, No. 3 - Mechanism of the Uranium-Water Reaction, HW - 61799, No. 4 Coextruded Tube Elements with Pinhole Defects and Various Annular Spacings, HW- 62348, No. 5- Comparison of In-Reactor and Ex-Reactor Ruptures, HW-62766. This work is being done in cooperation with the Fuel Element Design Operation of the Hanford Laboratories Operation. J. W. Goffard has been particularly helpful in supplying samples and useful discussions of the results.

The current interest in a tube-in-tube type Zircaloy-2 clad UO2 fuel element for use in the power reactors provided the incentive for a study of the dissolution of cladding from an annular space. The objectives of the study were to compare the estimated rate of dissolution in the annuli with rates on fully exposed metal. Because of an interest from the design standpoint, heat balance data from the study are reported.

The PRP Critical Facility is an experimental reactor for use in determination of basic nuclear constants of heterogenous reactors recycling plutonium, and exponential and criticality studies at power levels up to 100 watts and neutron fluxes of about 109 nv. Provision is made for changing reactor lattices using irradiated and unirradiated fuel elements with either a light or heavy water moderator.

This document describes required laboratory space and lists major equipment items necessary for a routine water quality laboratory in the P. R. T. R. Building. During discussions with R. D. Widrig and V. L. Rooney about the analytical sample program for the Plutonium Recycle Test Reactor, the author was asked to summarize equipment and space needs for a water control laboratory to provide routine analytical coverage on some of the water systems. Based upon 1706-KE-KER experience, some operating personnel may be used to provide analytical coverage on those routine analyses that are needed on around-the-clock basis with a savings of both time and money.

The chromium-nickel-manganese alloys are a group of austenitic stainless steels which were developed during the Korean War to conserve nickel. These alloys are very similar to their corresponding 300 Series grades in mechanical, physical and corrosion properties. A portion of the nickel in the 300 Series grades has been replaced by approximately 2% manganese for each percent of nickel replaced. Two compositions, AISI 201 and AISI 202, are recognized as standard grades. Two other compositions, AISI 204 and AISI 204-L, have been produced in limited quantities to replace AISI 304 and AISI 304-L. Experience with the 200 Series steels indication they are every bit as good as the grades for which they were once alternates. In some shapes, such as rod and sheet, the cost per pound is considerably lower than the corresponding 300 Series grades.

A preliminary evaluation of the autoclave corrosion behavior of a series of U-low C alloys and a series of U-low Zr alloys prepared by Fuels Fabrication Development Operation has been made. The corrosion testing was conducted by Coatings and Corrosion Operation by the experimental methods and procedure outlined in HW-61378.