An analysis of the temperature structure in the GCR2 fuel elements and coolant stream at the position where the maximum fuel element surface temperature exists was presented in a previous paper (CF-58-5-97). It was felt that the peripheral temperature variation existing on the fuel rods as brought out in that analysis was due mainly to the poor flow distribution of the coolant with respect to the heat flux. The most expedient way to alleviate this situation without changing the fuel element assembly itself is to scallop the channel so that it becomes, in effect, seven channels merged together to form a single passage. This geometry was studied by use of the IBM 704 digital computer in much the same way the earlier problems were investigated. Since the heat transfer coefficient depends much more strongly on free flow area than on equivalent diameter, the free flow area of the model reported on was made equal to that of the 3.25 in. circular channel so that a comparison of the results of the two configurations would be meaningful.(auth)

Thorium bismuthide when crystallized from a solution i bismuth results in large platelets which may be as large a 1 centimeter in diameter. A slurry of these platelets is difficult to pump through pipe lines and filters. The particle size can be reduced by (1) very rapid cooing (approximately 1000 degree C per second) or (2) ultrasonic treatment. The latter, much easier to attain in large scale, gives equiaxed particles of thorium bismuthide.

Inconel can be used for thermal neutron flux measurements by means of its cobalt impurity or its chromium constituent where conventional monitors are unsuitable. The use of cobalt should also be applicable to other nickel alloys. Discriminatory counting is required. (auth)