Analytical and experimental investigations of the behavior of thermal neutrons in lattices of uranium metal rods in heavy water

Statement of responsibility on title-page reads: R. Simms, I. Kaplan, T. J. Thompson, D. D. Lanning"October 11, 1963.""NYO-10211."Also issued by the first author as a Ph. D. thesis, Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1964Includes bibliographical references (leaves 193-199)Measurements of the intracellular distribution of the activation of foils by neutrons were made in lattices of 1/4-inch diameter, 1.03% U-235, uranium rods moderated by heavy water, with bare and cadmium-covered foils of gold, depleted uranium, lutetium, europium and copper. The measurements were made in the M.I.T. Heavy Water Lattice Facility with source neutrons from the M.I.T. Reactor. Two lattices were studied in detail in this work. The more closely packed lattice had a triangular spacing of 1.25 inches, and the less closely packed lattice had a triangular spacing of 2.5 inches. The results of the experiments were compared to one-dimensional, 30-energy group, THERMOS calculations based on the available energy exchange kernels. The comparison indicated that the approximation that the hexagonal cell may be replaced by an equivalent circular cell (the Wigner-Seitz approximation) can lead to serious discrepancies in closely packed lattices moderated b! y heavy water.A modified one-dimensional, and a two-dimensional, calculation were shown to predict the intracellular activation distribution in the closely packed lattice. An analytical treatment of the problem of the flux perturbation in a foil was developed and compared to the experimental results obtained by using gold foils of four different thicknesses in the lattice cell; the method was shown to be adequate. An analytical method to treat the effect of leakage from an exponential assembly was formulated; the results indicated that only in small exponential assemblies would leakage be a significant problem in intracellular flux measurements. A method was developed to predict the cadmium ratio of the foils used in the lattice cell; comparison with available measurements with gold foils indicated good agreement between theory and experiment, except for a lattice having very large ratios of moderator volume, to fuel volume, e.g., 100:1.Calculations of the fuel disadvantage factor by the method of successive generations for gold, lutetium and europium detector foils were compared to the results of THERMOS calculations, because THERMOS was shown to predict the experimental distributions. The comparison indicated that the method of successive generations is a good alternative to the THERMOS calculation, if all that is required is 17 and the thermal utilization.U.S. Atomic Energy Commission contract AT(30-1)234

Studies of epithermal neutrons in uranium, heavy water lattices

Statement of responsibility on title-page reads: W. H. D'Ardenne, T. J. Thompson, D. D. Lanning and I. Kaplan"August 24, 1964.""MIT-2344-2."Also issued as a Ph. D. thesis by the first author, MIT Dept. of Nuclear Engineering, 1964Includes bibliographical references (leaves 167-170)Measurements related to reactor physics parameters were made in three heavy water lattices. The three lattices studied consisted of 0.250-inch-diameter, 1.03 w/o U2 3 5 uranium fuel rods arranged in triangular arrays and spaced at 1.25, 1.75, and 2.50 inches. The following quantities were measured in each of the three lattices studied: the ratio of the average epicadmium U2 3 8 capture rate in the fuel rod to the average subcadmium U2 3 8 capture rate in the fuel rod ([sigma]28); the ratio of the average epicadmium U2 3 o fission rate in the fuel rod7 to the average subcadmium U 35 fission rate in the fuel rod (625); the ratio of the average U2 3 8 capture rate in the fuel rod to the average U2 3 5 fission rate in the fuel rod (C ); the ratio of the average U2 3 8 fission rate in the fuel rod to the average U2 3 5 fission rate in the fuel rod (628); and the effective resonance integral of U2 3 8 in a fuel rod (ER12 8 ).The results of an investigation of systematic errors associated with these measurements have-led to many changes and adjustments in the experimental techniques and procedure which have improved the general precision of the experimental results. A new method was developed to measure the ratio C * which simplified the experiment, significantly reduced the experimental uncertainty associated with the measurement, and avoided systematic errors inherent in the method used to measure C* in earlier work. The value of ER12 8 was also measured by a new method in which the results of measurements made in an epithermal flux which had a 1/E energy dependence are combined with the results of measurements made in a lattice.The experimental results were combined with theoretical results obtained from the computer programs THERMOS and GAM-I to determine the following reactor physics parameters for each of the three lattices studied: the resonance escape probability, p; the fast fission factor, E; the multiplication factor for an infinite system, k [infinity]; and the initial conversion ratio, C. Methods were developed to measure that portion of the activity of a foil which is due to neutron captures in the resonances in the activation cross section of the foil material. The resonance escape probability was determined by a new method, using the resonance activation date, in which the use of cadmium is not necessary.U.S. Atomic Energy Commission contract AT(30-1)-234

Use of neutron absorbers for the experimental determination of lattice parameters in subcritical assemblies

Statement of responsibility on title-page reads: J. Harrington, D. D. Lanning, I. Kaplan, T. J. Thompson"February 1966."AEC Research and Development ReportMIT-2344-6Includes bibliographical references (leaves 188-192)U.S. Atomic Energy Commission contract AT(30-1)234

Design, construction and evaluation of a facility for the simulation of fast reactor blankets

"February 1970."Statement of responsibility on title-page reads: I.A. Forbes, M.J. Driscoll, T.J. Thompson, I.Kaplan and D.D. LanningAlso issued as a Ph. D. thesis in the Dept. of Nuclear Engineering, MIT,1970"MIT-4105-2."Bibliography: leaves 123-125A facility has been designed and constructed at the MIT Reactor for the experimental investigation of typical LMFBR breeding blankets. A large converter assembly, consisting of a 20-cm-thick layer of graphite followed by a 17.5-cm-thick U0 2 fuel region, is used to convert thermal neutrons into fast neutrons to drive a blanket mockup. Operating at 55 watts, the converter generates blanket fluxes at an equivalent LMFBR core power of about 350 watts, with as little as one tenth of the blanket material required for a critical assembly. Calculations show that the converter leakage spectrum is a close approximation to the core leakage spectrum from reference LMFBR designs, and that the axial distribution of the neutron flux in the blanket assembly simulates that in the radial blanket of a large LMFBR when the effective height and width of the blanket assembly are correctly chosen. Testing of the completed facility with a blanket composed of 50 v/o iron and ! 50 v/o borax showed that the lateral flux distributions were cosine-shaped, and that lateral spectral equilibrium was achieved in a large central volume of the blanket. Backscattering from concrete shielding surrounding the experiment was found to affect no more than the outer 30 cm of the blanket assembly, confirming the results of two-dimensional multigroup calculations. Measurements of the axial activity of gold and indium show good agreement with 16- group, S8 ANISN calculations.U.S. Atomic Energy Commission contract AT(30-1)410

A Single-element method for heterogeneous nuclear reactors

Statement of responsibility on title-page reads, S.S. Seth, M.J. Driscoll, I. Kaplan, T.J. Thompson and D.D. Lanning"May 1970.""MIT-3944-3."Also issued by the first author and supervised by the second and third author as a Sc. D. thesis in the Dept. of Nuclear Engineering, MIT, 1970Includes bibliographical references (leaves 169-176)U.S. Atomic Energy Commission contract AT(30-1) 394

Studies of reactivity and related parameters in slightly enriched uranium, heavy water lattices

Statement of responsibility as it appears on title page reads: B. K. Malaviya, I. Kaplan, D. D. Lanning, A. E. Profio , T. J. Thompson"May 25, 1964."MIT-2344-1Includes bibliographical referencesU.S. Atomic Energy Commission contract AT(30-1)234

Strong-weak CP hierarchy from non-renormalization theorems

We point out that the hierarchy between the measured values of the CKM phase and the strong CP phase has a natural origin in supersymmetry with spontaneous CP violation and low energy supersymmetry breaking. The underlying reason is simple and elegant: in supersymmetry the strong CP phase is protected by an exact non-renormalization theorem while the CKM phase is not. We present explicit examples of models which exploit this fact and discuss corrections to the non-renormalization theorem in the presence of supersymmetry breaking. This framework for solving the strong CP problem has generic predictions for the superpartner spectrum, for CP and flavor violation, and predicts a preferred range of values for electric dipole moments.Comment: 36 pages, 3 figure

Ipilmumab and cranial radiation in metastatic melanoma patients: a case series and review

Background: Ipilimumab improves survival in metastatic melanoma patients. This population frequently develops brain metastases, which have been associated with poor survival and are often treated with radiation. Therefore, outcomes following ipilimumab and radiation are of interest, especially given case reports and animal studies suggest combined treatment may generate abscopal responses outside the radiation field. Findings: We reviewed sixteen consecutive melanoma patients who received 1 to 8 courses of radiation, with a sum total of 51, systematically evaluating abscopal responses by following the largest extra-cranial lesion. We also reviewed other series of patients treated with cranial radiation and ipilimumab. Our patients received between 1 and 8 courses of cranial radiation. Four patients received radiation concurrently with ipilimumab. Median survival was 14 months, and 17 months in patients initially treated with SRS. Interestingly, after radiotherapy, there was a 2.8-fold increased likelihood that the rate of extra-cranial index lesion response improved that didn’t reach statistical significance (p = 0.07); this was more pronounced when ipilimumab was administered within three months of radiation (p < 0.01). Conclusion: Our experience and review of recently published series suggest ipilimumab and cranial radiation is well tolerated and can result in prolonged survival. Timing of ipilimumab administration in relation to radiation may impact outcomes. Additionally, our results demonstrate a trend for favorable systemic response following radiotherapy worthy of further evaluation in studies powered to detect potential synergies between radiation and immunotherapy

"We're worth what we are paid": Unravelling the 'paradox of the contented female worker'

Pay satisfaction research has suggested that women are more satisfied with their pay than men, even though, in general, women earn less. This paper argues that this body of research has misconceptualised this phenomenon as an issue of women only. It also argues that previous explanations for this gender pay paradox have not adequately explained these patterns of satisfaction. A social constructionist approach to pay satisfaction is proposed which situates satisfaction within the context of structural inequality. This draws upon the scholarly work of feminist scholars and the conceptual ideas of Pierre Bourdieu. This theoretical approach is explored with data from qualitative interviews with support staff at universities in the United Kingdom. This evidence suggests that their pay satisfaction is influenced by beliefs about the ‘value’ of different occupations

Reactor physics project final report

"September 30, 1970."Statement of responsibility on title-page reads: Editors, M. J. Driscoll, I. Kaplan, D. D. Lanning, N. C. Rasmussen. Contributors: V. K. Agarwala, F. M. Clikeman, M. J. Driscoll, Y. Hukai, L. L. Izzo, I. Kaplan, M. S. Kazimi, D.D. Lanning, T.C. Leung, E.L. McFarland, N.C. Rasmussen, S.S. Seth, G.E. Sullivan, and A.T. SuppleIncludes bibliographical referencesFinal report; January 1, 1968 to September 30, 1970This is the final report in an experimental and theoretical program to develop and apply single- and few-element methods for the determination of reactor lattice parameters. The period covered by the report is January 1, 1968 through September 30, 1970. In addition to summarizing results for the entire contract period, this report also serves as the final annual report; thus, work completed in the period of October 1, 1969 through September 30, 1970 is dealt with in more detail than the earlier work. Methods were developed to measure the heterogeneous parameters 17, [Gamma] [eta] and [Alpha] for single fuel elements immersed in moderator in an exponential tank using foil activation measurements external to the fuel. These methods were applied to clustered fuel rods in D 20 moderator and single fuel rods in H 20 moderator, and the results were extended to and compared with data on complete multi-element lattices reported by other laboratories. Advanced gamma spectrometric methods using Ge(Li) detectors were applied to the analysis of both prompt and fission product decay gammas for the nondestructive analysis of the fuel used in this work. The latter includes both simulated burned fuel containing plutonium and actual burned fuel irradiated to 20,000 MWD/T in the Dresden BWR.U.S. Atomic Energy Commission contract AT (30-1)-394