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Title: MTR-ETR TECHNICAL BRANCHES QUARTERLY REPORT PERIOD ENDING MARCH 31, 1959

Abstract

In reactor technical assistance, a linearization technique was developed which yields a good prediction of charge life for MTR after a core has operated for some 60 Mwd. A detailed comparison of relative statistical weights proportional to the square of neutron flux and experimental statistical weights, showed the two in good agreement, both for MTR and for ETR. An MTR startup accident calculation (void formation neglected) indicated that doubling the withdrawal rate for shim rods increases the calculated energy release in the power transient by only 3%. In an investigation of service life of MTR shim rods, examination of a Be-Cd rod that had logged 20,000 Mwd revealed that the Cd had changed to flakes; a fuel-Cd rod with 2545 Mwd of service showed no corrosion damage. RMF measurements of the buildup of U/sup 233/ in MTR-irradiated Th slugs, made as part of a continuing program, were analyzed and results are presented. A gamma-insensitive control system for RMF-type reactors has been proposed, based on a loop ihrough which a liquid circulates from the reactor core to an external detector where its neutron activation is measured. A stability study showed flow control requirements to be reasonable. Additional total cross sections weremore » measured with the crystal spectrometer and fast chopper including those for Pu/sup 240/ U/sup 235/, U/sup 233/ Au, V, C, and B (in the thermal region) and for Pa/sup 231/, Np/sup 237/, and Ir (in the energy region <10 ev). Energy calibration for the fast chopper has been improved by certain recalibrations and corrections. A study of competing planes in crystals disclosed that competition between planes may cause serious discrepancies in crystal spectrometer measurements of reactor spectra. In the inelastic scattering studies, steam, methane, and vanadium measurements were completed and prelimi-nary measurements were made on graphite, water, nickel, and beryllium. Results are shown. A set of curved slits installed in the rotors has improved resolution of the velocity selector system. The relative ratios of asymmetric to symmetric fission in Pu/sup 239/ for thermal and 0.29 ev neutrons were measured. The and Pu/sup 239/ were calculated from latest cross section values for different pile neutron spectra. A decay scheme was iound for Nb/sup 94/ and Nb/ sup 94m. A new energy level scheme for Eu/sup 155/ was developed from measurements of gamma-rays emitted from a neutron-irradiated sample of Sm/sup 154/ . Preliminary studies of operational characteristics of a 4 ith Cr deposite counting system indicated that reliable precision determinations of absolute beta disintegration rates are readily obtained. A succession of IBM-704 runs with the TURBO code was found to give a good picture of ETR flux changes during the course of an operating cycle. The code furnishes a powerful tool for handling the problems of an unsymmetrical core. In addition to giving eigenvalues and flux distributions, which are obtainable from the simpler PDQ code, TURBO gives burnup of burnable'' nuclides for any specified time interval. Two important codes were developed for the IBM-650. One gives a solution to the problem of heat flow from a spatially distributed source during transient conditions, which has direct application to pressure vessels such as are used in in-pile loops and SPERT. The other is a code for inversion of Laplace Transforms by numerical methods, of value in studies of reactor control systems, where it is often necessary to perform this operation. (For preceding period see IDO-16534.) (auth)« less

Publication Date:
Research Org.:
Phillips Petroleum Co.
Sponsoring Org.:
US Atomic Energy Commission (AEC)
OSTI Identifier:
4208966
Report Number(s):
IDO-16543
NSA Number:
NSA-13-021723
DOE Contract Number:  
AT(10-1)-205
Resource Type:
Technical Report
Resource Relation:
Other Information: Orig. Receipt Date: 31-DEC-59
Country of Publication:
United States
Language:
English
Subject:
REACTORS; ACCIDENTS- CONTROL ELEMENTS- ETR- MATHEMATICS- MOTION- MTR- POWER- REACTORS- RODS- STARTUP- TRANSIENTS- ZONES; ACTIVATION ANALYSIS- CONTROL SYSTEMS- ETR- GAMMA RADIATION- IN PILE LOOPS- LIQUID FLOW- LIQUIDS- MTR- NEUTRON DETECTION- PIPES- REACTOR CORE- REACTORS- RMF- SENSITIVITY- STABILITY; ATOMS- CROSS SECTIONS- ELECTRIC CHARGES- ETR- IRRADIATION- MATHEMATICS- MTR- NEUTRONS- PLUTONIUM 239- REACTORS- SPECTRA- THORIUM 232- URANIUM 233- URANIUM 235- URANIUM 238; BERYLLIUM- CADMIUM- CONTROL ELEMENTS- CORROSION- ETR- FUELS- LAYERS- LIFETIME- MTR- POWER- REACTORS- RODS; BERYLLIUM- ETR- GRAPHITE-

Citation Formats

None. MTR-ETR TECHNICAL BRANCHES QUARTERLY REPORT PERIOD ENDING MARCH 31, 1959. United States: N. p., 1959. Web. doi:10.2172/4208966.
None. MTR-ETR TECHNICAL BRANCHES QUARTERLY REPORT PERIOD ENDING MARCH 31, 1959. United States. doi:10.2172/4208966.
None. Wed . "MTR-ETR TECHNICAL BRANCHES QUARTERLY REPORT PERIOD ENDING MARCH 31, 1959". United States. doi:10.2172/4208966. https://www.osti.gov/servlets/purl/4208966.
@article{osti_4208966,
title = {MTR-ETR TECHNICAL BRANCHES QUARTERLY REPORT PERIOD ENDING MARCH 31, 1959},
author = {None},
abstractNote = {In reactor technical assistance, a linearization technique was developed which yields a good prediction of charge life for MTR after a core has operated for some 60 Mwd. A detailed comparison of relative statistical weights proportional to the square of neutron flux and experimental statistical weights, showed the two in good agreement, both for MTR and for ETR. An MTR startup accident calculation (void formation neglected) indicated that doubling the withdrawal rate for shim rods increases the calculated energy release in the power transient by only 3%. In an investigation of service life of MTR shim rods, examination of a Be-Cd rod that had logged 20,000 Mwd revealed that the Cd had changed to flakes; a fuel-Cd rod with 2545 Mwd of service showed no corrosion damage. RMF measurements of the buildup of U/sup 233/ in MTR-irradiated Th slugs, made as part of a continuing program, were analyzed and results are presented. A gamma-insensitive control system for RMF-type reactors has been proposed, based on a loop ihrough which a liquid circulates from the reactor core to an external detector where its neutron activation is measured. A stability study showed flow control requirements to be reasonable. Additional total cross sections were measured with the crystal spectrometer and fast chopper including those for Pu/sup 240/ U/sup 235/, U/sup 233/ Au, V, C, and B (in the thermal region) and for Pa/sup 231/, Np/sup 237/, and Ir (in the energy region <10 ev). Energy calibration for the fast chopper has been improved by certain recalibrations and corrections. A study of competing planes in crystals disclosed that competition between planes may cause serious discrepancies in crystal spectrometer measurements of reactor spectra. In the inelastic scattering studies, steam, methane, and vanadium measurements were completed and prelimi-nary measurements were made on graphite, water, nickel, and beryllium. Results are shown. A set of curved slits installed in the rotors has improved resolution of the velocity selector system. The relative ratios of asymmetric to symmetric fission in Pu/sup 239/ for thermal and 0.29 ev neutrons were measured. The and Pu/sup 239/ were calculated from latest cross section values for different pile neutron spectra. A decay scheme was iound for Nb/sup 94/ and Nb/ sup 94m. A new energy level scheme for Eu/sup 155/ was developed from measurements of gamma-rays emitted from a neutron-irradiated sample of Sm/sup 154/ . Preliminary studies of operational characteristics of a 4 ith Cr deposite counting system indicated that reliable precision determinations of absolute beta disintegration rates are readily obtained. A succession of IBM-704 runs with the TURBO code was found to give a good picture of ETR flux changes during the course of an operating cycle. The code furnishes a powerful tool for handling the problems of an unsymmetrical core. In addition to giving eigenvalues and flux distributions, which are obtainable from the simpler PDQ code, TURBO gives burnup of burnable'' nuclides for any specified time interval. Two important codes were developed for the IBM-650. One gives a solution to the problem of heat flow from a spatially distributed source during transient conditions, which has direct application to pressure vessels such as are used in in-pile loops and SPERT. The other is a code for inversion of Laplace Transforms by numerical methods, of value in studies of reactor control systems, where it is often necessary to perform this operation. (For preceding period see IDO-16534.) (auth)},
doi = {10.2172/4208966},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1959},
month = {8}
}