HW-70780, {open_quotes}An Operational Reactivity Accounting System Based on One-Group Diffusion Theory{close_quotes} describes a reactivity accounting system which is an improvement over the present {open_quotes}flux-squared weighting{close_quotes} system. Several changes and additions have been made which will simplify and increase the accuracy of the system described in the parent document. The changes occur primarily in the application of the system and are compatible with diffusion theory and the parent document. Each change will be described briefly and to illustrate their application an example reactivity balance, using the reactivity accounting system, will be performed.

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This document is divided into the following sections: fuel element swelling model, tubular fuel element irradiations, and Zircaloy-2 cladding strain study.

The Hanford reactors have undergone numerous hydraulic changes which have increased production output either directly, as in the cases of raising bulk limited power levels, or indirectly, such as reorificing to accommodate major advances in pile flattening efficiencies. Unfortunately, whenever major hydraulic changes occur, Panellit pressures that had been prevalent also change, sometimes to the extent that efficient pile operation is affected. Therefore, when hydraulic changes occur, an investigation is generally made to seek a new orifice and/or venturi design that will not only alleviate the Panellit problem but also utilize the available reactor process water in the best possible fashion. The method presented in this document discusses the approach made at DR reactor. This method should, with few changes (mainly in limit requirements), apply to determining the optimum orifice size at any reactor. Each reactor flow system has individual perculiarities which necessitate a separate analysis to determine the optimum venturi size. There is some probability that one venturi size may represent an optimum selection for groups of reactors, notably the old reactors, K reactors, and C reactor. To some extent this has already been done in the form of the 0.283 venturi, 0.310 venturi, etc.

The objectives of this test are to determine the gross dimensional stability of hot pressed fuel and to evaluate bond quality differences between Al-Si bonds and solid state diffusion bonds. Irradiation testing will be conducted at C Reactor and will be carried out in two parts: Part 1, Sylcor and Hanford hot press diffusion bonding processes will be compared to the Hanford Al-Si bonding process. Eighteen (18) measured monitor columns of CVNS fuel elements will be irradiated to an 800 MWD/T goal exposure. Part 2, Hanford gas pressure and Hanford hot die sizing solid state diffusion bonding processes will be compared to the Hanford Al-Si bonding process. Again, eighteen (18) measured monitor columns of CVNS fuel elements will be irradiated to an 800 MWD/T goal exposure.

A computer program is described for the solution of shock, detonation, and spall problems for one-dimensional linear, cylindrical, or spherical hydrodynamic flow. The Flume option is used for calculating flow- through arbitrary cross sections. (R.J.S.)

The following criteria defines the objectives, bases and functional requirements that shall govern the preparation of the final design for the zirconium process tube installation program at the 100-K Areas. As a result of this program, reduced operating costs and increased production can be achieved. The present central zone aluminum tubes in the 100-K Reactors require replacement every to to three years to prevent excessive failures resulting from the thinning of the tube walls by corrosion. Replacement of the aluminum central zone tubes with zirconium tubes which have a negligible corrosion rate will substantially reduce the need for tube replacement and the attendant loss of production. Installation of the ribless zirconium tubes will, in addition, permit increased production through the use of self-supported fuel elements of improved performance.

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In a previous Naval Application memorandum, a discussion was given of what happens to the power level of a reactor when an instantaneous, very large neutron source is introduced. The motivation for the problem arises from the question of what happens when a nuclear bomb is detonated near a reactor powered missile. This present memorandum looks at the same problem as that which is discussed in the previous memorandum but in slightly more detail. The results obtained are essentially the same as those of the previous memorandum with somewhat more attention given to the nature of the assumptions made. The kinetics model used is the space-time separable, one delayed group model. Space-time separability is almost certainly a poor assumption in this case. When a very large neutron wavefront impinges on a reactor, the subsequent short time behavior can hardly be that predicted by this simple model. One would expect very large local power densities in one part of the core before another part would see anything unusual. The other assumption, one delayed group, is not necessary but makes the mathematics simpler and in view of the first assumption is probably quite acceptable. In spite of these simplifications the model gives …