NUCLEAR PHYSICS RESEARCH QUARTERLY REPORT FOR OCTOBER, NOVEMBER, DECEMBER 1957
Installation and calibration of the fast neutron time-offlight spectrometer were completed. Channel width uniformity and stability, data storage, and detector design are discussed. Neutron spectra obtained from the Be/ sup 9/ (d,n)B/sup 10/ reaction were in agreement with energy level data. Time resolution of two millimicroseconds was obtained. Experimental results are plotted which show the variation in the ratio of the ternary to total fission cross sections of U/sup 235/ with incident neutron energy. The results indicate the ratio is constant in the energy range 0.014 to 0.40 ev to a precision of 1%, and constant in the range 0.04 to 8.7 ev to a precision of 3 to 6%. A multichannel formula was developed far the analysis of fission cross sections where the compound nucleus formed has a few fission channels and many gamma decay channels open. Exponential pile measurements of material buckling were carried out with several different fuel elements and graphite-to-uranium ratios. Results obtained in cases with air coolant are correlated with theory. A theoretical attempt was made to explain the observed change in excess k in the Physical Constants Testing Reactor with the addition of buffer rod; the buffers being considered as line sources. Buckling messurements were made on random arrays of water moderated fuel elements to compare their buckling characteristics with uniform distributions. Material bucklings of graphite lattices with a solid 1.66 in. natural uranium rod were measured as a function of lattice spacing in air, water, and biphenyl. Results are tabulated. Measurements of the infinite multiplication constant for homogeneous mixtures of water and UO/sub 3/ with several enrichments were extended to include hydrogen-to-uranium ratios of about four. These and previous measurements are plotted as a function of H/U, with enrichment ss a parameter. The reflector savings of uranyl nitrate solutions of various uranium concentrations were determined relative to light water. Uranyl nitrate reflected, H/sub 2/O moderated, rhomboid lattice assemblies were used. Stainless steel was used as a lattice container, and its effect on reflector savings was evaluated. The results are presented, and the experiments are described and discussed. Theoretical values of the ratio of fast to thermal fission were calculated for a number of rod sizes between 0.96 and 3.88 in. and compared with experimental values. Both theo retical and experimental determinations are discussed. A study was made of the reactivity of a spherical core surrounded by a reflector which can not be made critical by itself. Plots of extrapolation length versus core material buckling and critical mass versus core material buckling are given. The effects of water density on the criticality of slightly enriched homogeneous systems were determined. Calculated critical pararaters, with and without the density correction, are given for 4.9, 3.0, and 1.5% enriched U/sup 235/ systems. (For preceding period see HW-53492.) (D.E.B.)
- Research Organization:
- General Electric Co. Hanford Atomic Products Operation, Richland, Wash.
- DOE Contract Number:
- W-31-109-ENG-52
- NSA Number:
- NSA-12-010906
- OSTI ID:
- 4305276
- Report Number(s):
- HW-54591
- Resource Relation:
- Other Information: Orig. Receipt Date: 31-DEC-58
- Country of Publication:
- United States
- Language:
- English
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