Activities in a program to develop techniques in the use of pulsed neutron sources to measure shutdown parameters related to large thermal power reactors are reported. The experimental work centers around aspects of detecting neutrons in the presence of 10/sup 7/ r/hr gamma fields. Boric acid experiments and Humboldt Bay experiments are reported.

Abstract: Three irradiation experiments are described which have been designed to study the behavior of fuel elements in a reactors superheated steam environment. The experiments were conducted in the Superheat Advanced Demonstration Experiment loop, Vallecitos Boiling Water Reactor. The results obtained demonstrated that 304 stainless steel fuel clad in unsatisfactory for use in nuclear super heat fuel sheath designs where plastic strain or plastic deformation is allowed to occur. The results were in agreement with those reported for a previous experiment in SADE (SH-4B) and constituted the basis for change in direction of the superheat fuel program in regard to both design and fuel sheath selection.

Abstract: The physical property variation of superheated steam differs sufficiently from most other gases to warrant experimental investigation of heat transfer performance. Results are reported here of measurements made in a uniformly heated circular duct with steam at 1000 psi. The data agree very well with the expression use for design purposes, which is based on information in the literature for heating of other gases as well as steam. This work was a continuation of that performed under Task (Heat Transfer) of the Nuclear Superheat Project, AEC Contract AT(04-3)-189, Project Agreement 13.

This technical report describes the development, design, operation, and performance of a full-circle, radial-vane steam separator for the boiling water section of a nuclear superheat reactor. Steam-water tests of this model have demonstrated that is has vane capacity in excess of that required for the 300-Mx(e) separate superheat reactor and for the 300-Mw mixed spectrum superheat reactor. It is proposed that the vane capacity requirement of the 600 Mw(e) separate superheat reactor may be attained by increasing the nozzle length.

From introduction: "This is the thirteenth in a series of quarterly reports which will cover the progress and results from the conceptual design, economic evaluations and research and development work performed by the General Electric Company as part of the Nuclear Superheat Project."