Report issued by the Oak Ridge National Laboratory discussing quarterly progress made by the Homogeneous Reactor Program. Descriptions of progress and studies conducted are presented. This report includes tables, illustrations, and photographs.

This letter is for the purpose of supplying the information that you requested at the meeting of the sub-committee on Project Vela. It is divided into three parts: (1) Radiations from nuclear weapons; (2) Backgrounds for Vela Signal Detectors; (3) Discussion of the NASA program.

A prototype of the two-coolant-region pump shaft freezeseals intended for application to the Hallam Power Reactor sodium pumps was fabricated. Tests under simulated reactor service conditions revealed satisfactory operation only when the lower of the two regions received heat from the circulating fluid (tetralin in the tests). With the inlet temperature of tetralin to the upper region of the seal maintained at 95 deg F and that to the lower region held in the range 240 to 285 deg F the sealfunctioned satisfactorily for 1100 hr. When 95 deg F coolant was circulated through both sections of the seal excessive cooling occurred, resulting in either improper formation of the seal or in seizure of the shaft when rotative speed was low. In this case, the cooling load on the seal varied directly with both shaft speed and bulk sodium temperature. A maximum cooling load of 2.56 kw occurred at a shaft speed of 840 rpm and with a bulk sodium temperature of 1000 deg F. (C.J.G.)

The check valve for the Hallam Power Reactor uses a knife-edge bearing for the flapper in place of the usual journal-type bearing. Mechanical cycling in sodium at 600 deg F was used to check operation of this bearing. A total of 309 mechanical cycles was completed with no apparent malfunctioning of the valve. Measured leskage rates were 0.46 gpm at 0.93 psig, 0.73 gpm at 3.4 psig. and 0.32 gpm at 5.9 psig. (M.C.G.)

Cavitational flow has been known to exist in-rear crossheader ``Parker`` fittings at B, D, and F Reactors for the last five or six years. Calculations showing initiation of cavitational flow as a result of high flow rates in the present fittings were verified by experimental data in 1954. A study is currently being conducted to determine the required plant modifications to obtain flow increases on the order of fifty percent above existing flows. This study and the results of preliminary tests that show nominal flow increases may be obtained by reaming rear crossheader fittings has focused attention on the condition of existing rear face piping. To obtain an estimate of the effect of cavitation in rear crossheader fittings resulting from past and current operating conditions, twenty one fittings were examined during the period October 6, 1959 to November 30, 1959. This document reports the inspection results.

Thermal oxidation of graphite in flowing CO2 is being studied at 650 to 850 C, in a single-pass gas system at atmospheric pressure, by observing weight loss rates. The method is used to provide comparative data for candidate reactor graphites. The effects on oxidation rates of graphite purity, structure, coke type, graphitization temperatures and other manufacturing variables are determined. In addition, the effects of gas flow rates and graphite surface to volume ratios are observed.