Report documenting ongoing research and development undertaken by the Metallurgy Division of the Oak Ridge National Laboratory.

An approximation is derived for the time constant which characterizes the rate of energy loss of fast ions moving through a plasma. Using particle and energy-balance equations a simple approximate criterion is derived for the estimation of the importance of energy degradation during plasma buildup in a DCX type machine. Next, there is derived the steady-state ion energy distribution for a case in which energy losses are to electrons at a given temperature and particle losses are by charge exchange. The distribution function is used to compute loss rate, upper critical current, ionization rate, and other functions of interest. Quantitative application is made to DCX-2 under various conditions of operation of carbon and deuterium arcs.

The development of nuclear reactors and other nuclear particle sources has given the analyst a new analysis method which can be successfully applied to the determination of microgram and submicrogram quantities of many elements. Known as "radioactivation analysis", this method is one in which an "activation" by some type of nuclear reaction is used to produce a radioactive isotope of the element to be determined. Since this radioisotope decays with its own characteristic radiations and half-life, it is possible to make radioactivation analysis a very specific analysis. Chemical separations of the radioisotope are employed whenever necessary and its radioactivity measured by some type of radiation counter.

The steady-state radial and axial temperature profiles of an E. G. C. R. 5 1/2" O. D. through tube are determined for the test condition of an attemperated fuel assembly operating at 1500 KW in the loop. The profiles are determined for the case of the central control rod fully inserted and bank insertion to 62 inches (Δk = 0.025). The data are presented in the form of tables and curves.

The pneumatic temperature probe (PIM) is a device for measuring gas temperatures by utilizing the dependency of the flow of gases through a restriction on the temperature and pressure conditions. The determination is made by measuring critical mass flow across a restrictive element such as a nozzle and by knowing the upstream pressure and other variables pertinent to the critical flow equation, computing the temperature at the entrance to the restrictive element. In practice it has been found useful to use two critical flow nozzles in series and measure the ratio of the pressures at the nozzle inlets, together with the temperature at the downstream nozzle. The limitations of present thermocouple materials for long term use at elevated temperatures makes resort to this device attractive on many installations.