Report documenting the progress of the Army Gas-Cooled Reactor Systems Program to develop a mobile, low-power, nuclear power plant for Military field operation.

In research in support of the GCRE, procedures for the fabrication of stainless steel-clad flat-plate fuel elements having a core of 28 w/o UN dispersed in an iron-18 w/o chromium--14 w/o nickel--2.5 w/o molybdenum matrix were developed. The preparation of UN and its compatibility with the components of the matrix alloy were studied. The UN for the program was prepared by nitriding uranium metal at 850 C and then dissociating the U/sub 2/N/sub 3/ produced to UN in a vacuum at 1300 C. In compatibility studies, UN reacted with nickel alone at 1800 F, but no reaction with nickel was observed when the other matrix components were also present. The effects of fabricational variables were evaluated by metallographic examination, longitudinal and transverse tensile tests, bend tests, and corrosion tests. Studies indicated that minus 200 plus 325-mesh UN dispersed in a minus 325-mesh elemental-powder matrix rolled green vith a 30 per cent initial reduction at 2100 F and then annealed 3 hr at 2300 F produced the best fuel core. (auth)

Development of a fabrication process and the manufacture of 95 PRTR process tubes demonstrates that the commercial fabrication of high quality Zircaloy-2 pressure tubing is feasible.

This report analyzes a linear, hard-core pinch tube built to examine tubes afflicted by small-scale instabilities evident from many observations.

This report describes a toroidal version of the hard-core pinch and the additional information it can obtain to what the analogous linear pinch can get.

It is well known that a pinch column with internal H/sub Z/ and external conducting shell can be made grossly stable, but that small-scale instabilities persist; especiaily in the tubular region of maximum current density. To investigate further these small-scale instabilities of the stabilized pinch,'' we are using 12-in.-i.d. linear pinch tube with a 3-in.-o.d. insulated center rod. By controlling a current along this rod, as well as a current along external conducting straps, and a third current in an external H/sub z/ coil, it is possible to create many grossly stable pinch configurations. The small-scale stability of the tubular region of maximum current density can thus be studied for a wide range of internal and external magnetic field vectors. The magnetic field distribution in each discharge is obtained by a string of 10 magnetic pick- up loops. The distribution of plasma density is determined by modulating the inner or outer wall current and measuring the radial velocity of the resultant compressional Alfven waves. In one experiment, an initial H/sub z/ is entrapped in plasma by preionization, and then pushed radially outward from the rod by a rising H/sub theta /. The resultant field distribution, in which H/sub theta / …

The toroidal version of the hard-core pinch tube is created by levitating a ring conductor inside a toroidal shell. The magnitude of induced H/ sub theta / necessary for levi-tation is small in terms of field strengths normally desired for energetic pinches. In a 3-in. glass-and-copper toroid of square cross section a 3/4-in. hollow copper ring has been levitated with a 60- cycle current of 3 kiloamperes. A 12-in stainless steel tube of round cross section is being built. The stability of nearvacuum field hard-core configurations is best investigated in toroidal geometry. At high power levels and low plasma densities, the conventional toroidal stabilized pinch'' is subject to an anomalous plasma energy leakage to the wall, which cannot be explained by the observed ultraviolet radiation alone. A critical question is, therefore, whether the relative stability of some hard-core pinches, as reflected by the smoothness and reproducibility of magnetic probe traces, is reflected by an improved containment of the plasma en-ergy leading to high temperature. A toroidal hard-core tube is also useful in studying the nature of the nonhydromagnetic instabilities observed in the linear inverse stabilized pinch.'' The presence and condition of electrodes appear to have a substantial effect on the …

Since the calculation of the PRTR energy distribution was first carried out by J. R. Triplett, the design has become sufficiently fixed to allow a refinement of his values. The present analysis, also, includes a calculation of the fraction of energy which is released in the shroud and process tubers that flows to the primary coolant to the top and bottom shield coolant is taken into consideration. Nuclear data used in the original calculations still appears satisfactory and is, therefore, utilized in the present analysis.

The compatibility of zirconium diboride, boron carbide, and boron nitride with type 304 stainless steel was evaluated as a function of temperature (1000-1200°C), time (1-3 hr). Appropriate loadings of the boron compounds and stainless steel powder were blended and fashioned into a compact powder metallurgically. Each compact was roll clad into a plate and subsequently heat treated at a temperature equal to the initial sintering temperature. Metallographic examination of the fabricated and heat-treated plates demonstrated that none of the systems were metallurgically stable. The instability was generally manifested by the (1) interaction of the discrete boron compounds with the matrix and (2) precipitation of a hypothetically boron-rich phase throughout the stainless steel matrix material.

The compatibility of zirconium diboride, boron carbide, and boron nitride with type 304 stainless steel was evaluated as a function of temperature (1000 to 12OO deg C), time (1-3 hr). Appropriate loadings of the boron compounds and stainless steel powder were blended and fashioned into a compact powder metallurgically. Each compact was roll clad into a plate and subsequently heat treated at a temperature equal to the initial sintering temperature. Metallographic examination of the fabricated and heat-treated plates demonstrated that none of the systems was metallurgically stable. The instability was generally manifested by the interaction of the discrete boron compounds with the matrix and precipitation of a hypothetically boron-rich phase throughout the stainless steel matrix material. Of the three compounds, boron nitride was relatively the most stable in a stainless steel matrix under the test conditions. (auth)