The steady-state and dynamlc characterlstics of the Pathfinder systems were simulated on a dual-console Pace Analog Computer. The derivation of the system equations, the assumptions involved, their numerical evaluation, and their conversion to analog circuitry are described. The Pathfinder system is unique because of the internal nuclear superheater, and controlled, forced recirculation. In simulating this system the following major assumptions were maden the reactor is a boiling-water type; moderated and cooled with saturated, light water; pressurized between 400 and 800 psiai and has a neutron flux distribution that is spatially invariant. All the importanit non-linearities are retained, thus permitting accurate solutions of large system disturbances. The neutron kinetics equations, with their six groups of delayed neutrons, are simulated with power feedbacks through reactor pressure, steam flow, core inlet subcooling, and fuel- element temperature. Particular attention ls devoted to the accurate simulation of fuel-element heat transfer; the reactor pressure-control system, which operates the turbine inlet valves; and the effect of core inlet subcooling, sinee these were found to have pronounced effects on reactor performance. The transient temperatures at the superheater hot spot and exit are generated. Enough flexibility ss included, so that all important disturbanees possible in the actual plant can …

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Currently, all normal production HAPO fuel cores are rolled into rods at Fernald, consequently, HAPO is dependent upon one vendor for a critical raw material. This arrangement does not appear to be consistent with good business practice, and it is desirable to have an alternate fuel source tested and available. Mallinckrodt`s Weldon Spring plant contains an extrusion press for the gamma bar extrusion and a logical sequence of operations should permit further extrusion in the alpha phase to the desired rod size. As alpha extrusion is also purported to be a slightly cheaper fabrication process than rolling, it appears appropriate to carry out a testing program to evaluate the alpha extruded fuel core as an alternate to the rolled fuel core. The specific objectives of this test are to evaluate: (1) the gross dimensional stability and (2) the gross irradiation performance of alpha extruded dingot uranium fuel cores. The ultimate objective of this test program is to establish an independent alternate uranium fuel core feed source.

The existing K-Downcomer has the capacity for the new design flow rate, provided the temperature is limited. As the temperature increases, the entrance elbow commences to show cavitation and its capacity is greatly reduced. This capacity is not sensitive to flow rate, but is very sensitive to barometric pressure and the temperature of the flow. Flow as low, as 85,000 gpm exhibit the choking effect at approximately the same temperature as 20,000 gpm. Removal of the orifice plate and effluent back pressure did not influence this choking restriction. If the temperature is kept below the critical value for choking, rounding of the upstream edges of the orifice holes reduces the water level at entry to the entrance elbow about 6-inches, prototype. This report details model tests performed to evaluate prototype behavior for increased flow rats and to recommend those changes required for satisfactory prototype performance. Specific requirements include capability of the orifice plate, downcomer, entrance elbow, and approach tank to pass the design flow rate at the design temperature. Some margin of safety at these conditions is desirable.

This tabulation of data collected since 1952 by the author was made in response to a request by the Atomic Energy Commission. It is understood it is to be transmitted to the Bureau of Reclamation for their information. The data are to afford basic information to support the Bureau`s decision in regard to a third power house at Grand Coulee Dam.

This report covers the S-I-5-B-M fuel irradiation in the GETR Maritime Loop during the second quarter of fiscal year 1962. The data are summarized in Section II. Discussions on fuel performance, fuel environment (water chemistry), problems with loop operations, and the crud deposition program are included.

Final design for the 30 megawatt intermediate heat exchanger and steam generator.