![]() The procedure includes a reactor model and a cooling pool model. ![]() The article describes calculation procedure for reconstruction of radionuclide composition and activity of fission fragments accumulated in the irridated uranium from “Mayak” PA graphite-uranium reactors at the moment, when irradiation is completed, and at the moment, when the uranium is transferred to radiochemical processing (plant B) in the early 1950s. These include a least squares program for use in calibrating the ARMF reguiating rod, a gamma spectrum interpolation scheme for use in generating analyzer response curves, an IBM-704 code for hot channel analysis in SPERT III, a nonlinear least squares program for the IBM-650, a program for use on the IBM-650 to edit input dath for the IBM-704 code PDQ, and a comprehensive MTR-ETR pricing and recordkeeping program for the irradiations in these reactors. A number of new programs and computing techniques for the IBM-650 (and one for the IBM-704) were developed. An all-electronic scanning switch was developed to replace an existing 10 pole 100 position motor-driven rotary switch used to translate scaler data into a form usable by computer equipment. A new end-window proportional counter was developed with improved geometry that minimizes the positive slope of the voltage plateau. Continuing studies on gamma rays from the decay of both Pu/sup 2//sup 3//sup 9/ and Pu/sup 2//sup 4//sup 0/ resulted in gamma ray energy measurements not previously reported. ![]() A program undertsken to determine the spin of the 512 kev level of decay of 2.3 d Np/sup 2// sup 3//sup 9/ by use of directional correlation measurements resulted in a preliminary level scheme. A previously unreported 3.14 hr isometric level was found in Y/sup 9//sup 0/ at 0.685 Mev. These measurements served to demonstrate the reliability of the experimental procedures and provided insight and valuable checks upon the theory as applied to a simple case. Neutron inelastic scattering measurements from methane were completed and compared with theoretical predictions based upon gas models. The 27,000 b capture cross section of Pm/sup 1//sup 4//sup 8/ (T/sub 1//sub ///sub 2/ = 40.6 d) is of considerable reactor interest as a material produced from fission products at high fuel burnup. Various integral cross sections in reactor spectra were undertaken. Scattering measurements for samples of U/sup 2//sup 3//sup 3/ were undertsken on the fast chopper. Experimental results to date are primarily concerned with measurements of the corrections required. Measurements of U/sup 2//sup 3/ eta values using the Mn bath technique with the monochromatic crystal spectrometer neutrons were continued. Analyses of the total cross sections for Pu/sup 2//sup 4//sup 1/ and Pa/sup 2//sup 3//sup 1/ were ess entially completed, and a final report for Pu/sup 2//sup 4//sup 1/ was submitted for publication. Hydraulic tests made on roughened fuel plates indicated roughening as a possible means of increasing the heat transfer rate during forced convection cooling. Irradiation of a highly enriched 54 wt.% UO/sub 2/-Al fuel plate sample to 56% U/sup 2//sup 3//sup 5/ burnup produced a reaction (flssion damage) zone around the UO/sup 2/ particles. Experimenthl techniques are being developed for measuring the l/E component of neutron flux in several experimental positions of the RMF. Heat transfer calculations are being made on a thorium slug in the form of a thick-walled tube, which it is proposed to irrddiate, instead of the present solid slug, for U/sup 2//sup 3//sup 3/ production in the MTR high flux. The design aim of the ARMF is to achieve the maximum sensitivity and reproducibility possible with more stable operation more » and better control than in the RMF. The Advanced Reactivity Measurement Facility (ARMF) is now supplementing the Reactivity Measurement Facility (RMF) in making reactor physics measurements on small samples. Excess reactivities calculated from these calibrations by three definitions give maximum values of from approximately 13.5 to 15.5%. MTR shim rod calibrations were made for Cycle 146- B by distributed poison techniques. Experimental and calcuiated results show that flux flattening is accomplished by moving the boron burnable poison in ETR fuel elements from the fuel region to the sideplates.
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