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Title: PHYSICS DIVISION SUMMARY REPORT. JANUARY-FEBRUARY 1961

Abstract

Activities are outlined in various areas of effort including experimental nuclear physics, mass spectroscopy, and general theoretical physics. Separate abstracts were prepared for each paper. (J.R.D.)

Publication Date:
Research Org.:
Argonne National Lab., Ill.
OSTI Identifier:
4031837
Report Number(s):
ANL-6288
NSA Number:
NSA-15-016177
DOE Contract Number:
W-31-109-ENG-38
Resource Type:
Technical Report
Resource Relation:
Other Information: Orig. Receipt Date: 31-DEC-61
Country of Publication:
United States
Language:
English
Subject:
PHYSICS; MASS SPECTROMETERS; MEASURED VALUES; NUCLEAR REACTIONS

Citation Formats

None. PHYSICS DIVISION SUMMARY REPORT. JANUARY-FEBRUARY 1961. United States: N. p., 1961. Web. doi:10.2172/4031837.
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None. PHYSICS DIVISION SUMMARY REPORT. JANUARY-FEBRUARY 1961. United States. doi:10.2172/4031837.
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None. Tue . "PHYSICS DIVISION SUMMARY REPORT. JANUARY-FEBRUARY 1961". United States. doi:10.2172/4031837. https://www.osti.gov/servlets/purl/4031837.
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@article{osti_4031837,
title = {PHYSICS DIVISION SUMMARY REPORT. JANUARY-FEBRUARY 1961},
author = {None},
abstractNote = {Activities are outlined in various areas of effort including experimental nuclear physics, mass spectroscopy, and general theoretical physics. Separate abstracts were prepared for each paper. (J.R.D.)},
doi = {10.2172/4031837},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue Oct 31 00:00:00 EST 1961},
month = {Tue Oct 31 00:00:00 EST 1961}
}
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Technical Report:
View Technical Report (2.02 MB)
DOI:  10.2172/4031837
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  • 8 7 < 6 ; : : = 8 g developed for recovering fissionable and fertile materials from shortcooled reactor fuels. The second laboratory demonstration of the melt-refining process with highly irradiated EBR- IItype fuel pins was completed. A 392-g charge of U-5% fissium fuel pins irradiated to an estimated burnup of 0.4 total at.% and cooled 28 days was melt refined for three hours at 1400 deg C. Data were not obtained on the behavior of fission products. The effect of N concentration on the nitridation rates of unirradiated U-fissium alloys in Ar-N atmospheres was determined. Experiments on themore » storage of fuel pins at 350 deg C in Ar atmospheres showed that the presence of 5% N lowered product yields only slightly during subsequent melt-refining operations. Supplementary pouring techniques, such as the use of probes and mashers designed to break crusts over the melts, are moderately effective, but are a less desirable solution to the problem of maintaining high yields than the elimination of contaminants in the Ar atmosphere. A liquid metal process is under development for recovery of the fissionable material contained in melt refining crucible skulls produced in the EBR-II fuel cycle. Information obtained in separate studies of the individual process steps is listed. A systematic study is underway to ascertain the influence of atomic size, metallic valence, and electronic configuration on the coprecipitation of various metallic elements with the Cd-Ce intermetallic phase CeCd/sub 11/. Values for the coprecipitation coefficient lambda , defined by the equation log (tracer in solution/ total tracer) = lambda log (carrier in solution/total carrier), were determined for Na, Li, K, Y, Ba, lambda = 0; La, lambda = 1.49; Th, lambda = 1.08; Pr, lambda = 0.63; Ga, lambda = 0.23; Sm, lambda = 0.17; U, lambda = 0.13; Sr, lambda = 0.10; Eu, lambda = 0.099; Sc, lambda = 0.05; and Zr, lambda = 0.04. In pilot-plant studies the reaction of 304 stainless steel tube sections with Cl was investigated in a 1 1/2-inchdiameter two-zone fluid-bed reactor. An average penetration rate of 4.6 mils/hr was obtained in a 4.7-hour run at 575 deg C using 87% Cl (in N). At 625 deg C, using the same Cl concentration, a 35-mil tube completely reacted in 3.8 hours. The effect of Cl dilution at 625 deg C was noticeable at concentrations below 48 vol.%. The rate of thermal decomposition of PuF/sub 6/ was studied at 140 to 173 deg C by a static method and from 150 to 250 deg C by a flow method. A study of the kinetics of decomposition established the mechanism of the reaction. The rate of the reaction has been formulated as concurrent first- and zero-order reactions with respect to PuF/sub 6/ pres sure in the range between 50 and 1100 mm at 140 to 170 deg C. The reaction of elemental Br with PuF/sub 6/ has been investigated. The stoichiometry of the reaction was established. Primary products of the reaction are PuF/sub 4/ and BrF/sub 5/. The utility of the reaction for the separation of U and PuF/sub 6/ was demonstrated. In studies of fission product behavior, mixtures of UO/sub 2/ - Ru/sup 106/ were reacted with F at 400 and 500 deg C. It was found that at both of these temperatures Ru was volatilized at a rate equal to or faster than that of U volatilization as UF/sub 6/. However, it was found that RuF/sub 5/ decomposed and was deposited on a colder portion of the walls of the fluorination vessel. Two series of in-pile, metal-water experiments were completed. Meltdowns were conducted on stainless steel-urania cermets, U wires, and on ceramic core, metal-clad fuel specimens. Cermets made of 90 wt.% stainless steel with urania showed similar behavior when submerged in water irrespective of whether the sample was in the form of pins or plates; metal temperatures greater than 1500 deg C were attained. The original geometry was changed into one or two large globules together with many fine particles; the more energetic transients also produced some fine (1-mil diameter) powder. Chemical analyses indicated that a separation of the urania from the stainless steel took place during the melting-quenching cycle of the reactor burst. The larger globules were depleted in U« less

  • Nuclear Physics Research. Investigations into various properties of nuclear excited states are continuing. Of special interest is a state in Ne/sup 20/ at 5 Mev which was believed to be involved in the thermonuclear reactions producing neon from helium in the stars. The lifetime measured was anomalously long and led to new measurements of the spin and parity. The spin and parity found show that this level cannot be excited in the thermonuclear reactions proposed and have led to revisions in the current ideas about the creation of elements in the universe. Crystal Dynamics of Sodium Iodide. The longitudinal opticalmore » vibrations make up the highest frequency branch of elastic waves in a crystal. In these longitudinal waves the ions of opposite charge are moving in opposite phase. Recently the frequency wave-number dispersion relation for this branch in sodium iodide was carefully studied with a constant "Q" spectrometer at the NRU reactor. A specially pure Nal crystal with very small mosaic spread was used. The results confirm a general relation between frequencies and elastic constants, but are in disagreement with predictions of the current "shell model" used for ionic crystals. An analysis of the results may give detailed information on the distortion of the large negative ions induced by the fast coherent motions of the light positive ions. Developments in Theory. Theoretical studies were carried out on a number of problems in connection with power reactor fuel cladding, which include the expansion of UO/sub 2/ pellets subjected to a radial temperature variation, the diffusion of oxygen in zirconium metal, and the diffusion of hydrogen in Zircaloy. The (n, alpha ) cross section of O/sup 16/ at energies of 4 to 10 Mev was estimated for use in reactor calculations. The Datatron continues to perform satisfactorily with useful operation being about 450 hours per month. Developments in Electronics. The 900-channel coincidence kicksorter was installed in the Tandem Van de Graaff building and pre liminary trials were satisfactory. The encoder used in the 900- channel analyzer was further developed and the improved version will replace the vacuum-tube type now used in the Chahk River 100-channel kicksorter. In addition to increased reliability the temperature stability, differential linearity, and stability against count-rate were all improved. The use of high resolution semiconductor detectors for alpha spectrometry has emphasized the need for extreme stability in pulse height analyzers. To this end work was begun on the stabilization of spectrum position by a control system feeding information related to drift back to the system again. The first results indicate that a considerable improvement in resolution can be obtained. The work on particle detection in scintillating materials by pulse shape discrimination was continued. With a combination of pulse shape and pulse height analysis the following result is obtained: when 99.5% of the gamma-ray pulses from RdTh above 400 kev are rejected by pulse shape discrimination 65% of the 2.5 Mev neutrons detected by the counter from the D(d,n) reaction and 75% of the 14-Mev neutrons from the T(d,n) reaction are counted. (auth)« less

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