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Title: SNAP SHIELD TEST EXPERIMENT FISSION-PLATE POWER CALIBRATION

Abstract

Three techniques were employed in measuring the fission rate of the STE (SNAP Shield Test Experiment) fission source plate; the thermal neutron absorption rate, power dissipation (calorimetric method), and the fission-neutron production technique. The results obtained, when weighted according to the reciprocal of the squares of the estimated errors, yielded a fission rate of 1.97 x 10/sup 12/ fissions/sec plus or minus 4% for a STE reactor power level of 50 kw. Assuming that 190 Mev of usable energy is liberated per fission of U/sup 235/ , this fission rate corresponds to a fission-plate power of 59.9 watts plus or minus 4%. The calorimetric calibration technique proved to be the most satisfactory of the three techniques used. The design of the STE fission source plate allowed the plate to be enclosed completely in fiberglass insulation and heated electrically as well as by nuclear means. The heating rate is sufficiently high that errors caused by ambient temperature changes are negligible. Details of the three calibration techniques employed are given. The average fission-plate power per unit area was determined to be 2.05 x 10/sup -2/ watts/cm/sup 2/ plus or minus 4%, or about 14 times that of the Oak Ridge National Laboratorymore » (ORNL) Lid Tank Facility fission plate. Although this is one- sixth that of the design value (apparently due to graphite contamination), it is satisfactory for the initial shield measurements of the SNAP Reactor Development Program. The possibility of raising the power of the fission plate at least a factor of 5 through modification of the bismuth window and graphite thermal column is being investigated. In addition, the reactor power is capable of an increase from 50 to 500 kw for shortperiod operation by minor changes in the external piping and replacement of the primary coolant pump. Extended operation of 500 kw would necessitate the addition of a larger heat exchanger. Ultimately, however, the STE reactor fission plate is limited to a power of about 500 watts without supplementary radiation shielding. (auth)« less

Authors:
Publication Date:
Research Org.:
Atomics International. Div. of North American Aviation Inc., Canoga Park, Calif.
OSTI Identifier:
4758413
Report Number(s):
NAA-SR-7432
NSA Number:
NSA-16-032519
DOE Contract Number:  
AT(11-1)-GEN-8
Resource Type:
Technical Report
Resource Relation:
Other Information: Orig. Receipt Date: 31-DEC-62
Country of Publication:
United States
Language:
English
Subject:
PHYSICS; BISMUTH; COOLANTS; ENERGY; ERRORS; FISSION; GLASS; HEAT EXCHANGERS; HEATING; MEASURED VALUES; MEV RANGE; PIPES; PLATES; PUMPS; REACTORS; RESEARCH REACTORS; SHIELDING; SNAP SYSTEMS; SPACE VEHICLES; ST-E; STANDARDS; THERMAL NEUTRONS; URANIUM 235; NESDPS Office of Nuclear Energy Space and Defense Power Systems

Citation Formats

Tomlinson, R L. SNAP SHIELD TEST EXPERIMENT FISSION-PLATE POWER CALIBRATION. United States: N. p., 1962. Web. doi:10.2172/4758413.
Tomlinson, R L. SNAP SHIELD TEST EXPERIMENT FISSION-PLATE POWER CALIBRATION. United States. doi:10.2172/4758413.
Tomlinson, R L. Wed . "SNAP SHIELD TEST EXPERIMENT FISSION-PLATE POWER CALIBRATION". United States. doi:10.2172/4758413. https://www.osti.gov/servlets/purl/4758413.
@article{osti_4758413,
title = {SNAP SHIELD TEST EXPERIMENT FISSION-PLATE POWER CALIBRATION},
author = {Tomlinson, R L},
abstractNote = {Three techniques were employed in measuring the fission rate of the STE (SNAP Shield Test Experiment) fission source plate; the thermal neutron absorption rate, power dissipation (calorimetric method), and the fission-neutron production technique. The results obtained, when weighted according to the reciprocal of the squares of the estimated errors, yielded a fission rate of 1.97 x 10/sup 12/ fissions/sec plus or minus 4% for a STE reactor power level of 50 kw. Assuming that 190 Mev of usable energy is liberated per fission of U/sup 235/ , this fission rate corresponds to a fission-plate power of 59.9 watts plus or minus 4%. The calorimetric calibration technique proved to be the most satisfactory of the three techniques used. The design of the STE fission source plate allowed the plate to be enclosed completely in fiberglass insulation and heated electrically as well as by nuclear means. The heating rate is sufficiently high that errors caused by ambient temperature changes are negligible. Details of the three calibration techniques employed are given. The average fission-plate power per unit area was determined to be 2.05 x 10/sup -2/ watts/cm/sup 2/ plus or minus 4%, or about 14 times that of the Oak Ridge National Laboratory (ORNL) Lid Tank Facility fission plate. Although this is one- sixth that of the design value (apparently due to graphite contamination), it is satisfactory for the initial shield measurements of the SNAP Reactor Development Program. The possibility of raising the power of the fission plate at least a factor of 5 through modification of the bismuth window and graphite thermal column is being investigated. In addition, the reactor power is capable of an increase from 50 to 500 kw for shortperiod operation by minor changes in the external piping and replacement of the primary coolant pump. Extended operation of 500 kw would necessitate the addition of a larger heat exchanger. Ultimately, however, the STE reactor fission plate is limited to a power of about 500 watts without supplementary radiation shielding. (auth)},
doi = {10.2172/4758413},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1962},
month = {8}
}