This is one of twenty-one volumes summarizing the Aircraft Nuclear Propulsion Program of the General Electric Company. This volume summarizes the methods and techquies developed for use in the thermal design of nuclear reactors associated with that program.

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The objective of the Production Tests described in this report is to evaluate the operational aspects of a proposed method for reducing minimum downtime. The excess xenon poisoning, which occurs during the first 32--38 hours after the shutdown of a reactor from present equilibrium levels, will be partially overridden by a central enriched zone whose added reactivity contribution would be compensated during normal operation by means of poison splines. The test will be performed at B Reactor.

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The objective of this supplement to Production Test IP-377-A is to evaluate the behavior of N Reactor inner fuel tubes with modified end closures during irradiation in the KER Loops. Natural and 0.947% enriched N Reactor inner fuel tubes (NINl and NIEl elements) with contoured end closures are authorized for irradiation in the KER Loops to exposures no greater than 2500 MWD/T. The modification consists of machining a V groove in the uranium after counterboring and using an end cap shaped to fit the groove. Both brazed and unbonded closures will be evaluated.

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The object of this test is to determine the hydraulic characteristics of the proposed overbore process tube assembly designs which are to be installed on 105-C reactor for the 40 tube overbore fuel element test.

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This report provides information on the use of the model test data to predict prototype performance and to compare prototype and model results and, an orifice design having specified minimum pressures at the vena contracta for a range of flow rates.

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It was necessary to provide a basis for the design of modifications to the 190-K pumping units to achieve increased process water flow rates. The prototype pumping unit was inspected for cavitation damage after 3 months operation. The low lift pump impeller showed no cavitation damage, while the high lift pump impeller showed excessive damage. The lower max flow capacity and slightly increased power requirements of the third prototype impeller should not preclude its use if its cavitation performance proves satisfactory. Required combined five and six pump flow rates would be achieved with proper sizing of impeller diameter. Adequate margin of safety would exist between design operating points (five and six pump operating points) and max capacity. Under four pump operating conditions, the flow would be reduced 1% below that of the first impeller design, and the bulk outlet temperature surge would be increased one degree following instantaneous reduction to four pump operation.

This test is designed to obtain up-to-date information on heat decay values following a reactor scram. More specifically its purpose is to determine the effect of increased outlet water temperatures upon this heat output value. A recent review of the ``last ditch`` cooling system at the Hanford reactors indicated that at some reactors this backup coolant supply did not meet our coolant adequacy criteria at certain critical times after the loss of electric and steam pumping power. On the basis of this review, a high priority program is underway to bring the adequacy of reactor backup cooling systems into conformance with the criteria. An important part of this program lies in improving the accuracy of certain basic elements of reactor cooling conditions following a power loss. Primarily these are: Accurate reactor low flow values; and accurate reactor heat output values. A program is already in progress to improve both the amount of last-ditchcooling flow and to improve the accuracy with which this flow is determined.

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Recent studies have confirmed that large incentives exist for overboring the reactor process channels approximately 500 mils in the C and five old reactors, under the updated Plant Improvement Program. Conservative estimates of the incentives for overboring indicate a payout period of about two years for the proposed work, an increase in plutonium production of 15--18%, derived from increased conversion ratio and a reduction in plant unit cost. The proposal to overbore the graphite channels approximately 500--550 mils in one or more of the present Hanford reactors will require fuel elements about 0.5-inch larger in diameter than the present I & E fuel elements. Since there is only limited experience at HAPO in fabrication and irradiation of large diameter fuel elements, it is highly desirable to secure additional experience to assure that large fuel element technology will be available for full scale reactor use in advance of the time when extensive overboring of the old reactors is implemented. This report presents the design of the test to fabricate and irradiate the oversize (PIP-1) fuel elements.