Summary of the ORNL shield design supporting analysis for the FFTF

Conference · Sat Jan 01 04:00:00 EST 1977

OSTI ID:7283731

Engle, Jr, W W; Mynatt, F R; Emmett, M B

From 1969 through early 1976, Oak Ridge National Laboratory was requested by the Westinghouse Advanced Reactors Division (WARD) to analyze various shields WARD designed for the Fast Flux Test Facility (FFTF). To develop the proper methodology for such a large and complex system, it was necessary to improve the basic cross-section data sets for sodium and iron and to devise calculational techniques which would allow some regions to be treated in detail and would also allow the analyses to be carried out in steps that could be coupled to each other. These requirements necessitated the performance of two types of experiments: measurements of radiation transport through bulk samples (simple geometry) of important FFTF materials; and measurements of radiation transport through mock-ups of specific geometric regions of the FFTF. The successful analyses of these experiments allowed the application of the derived data sets and various combinations and adaptations of the DOT discrete ordinates and MORSE Monte Carlo transport codes to the FFTF system itself. The first series of calculations for the full system revealed that a cavity surrounding the reactor vessel provided a pathway for neutrons to stream up to the head compartment. Also, fissions in fuel elements stored in the outer region of the reactor vessel were found to contribute significantly to the cavity streaming. As a result, the major ORNL effort was expended on analyzing various designs of a concrete shield to be added in the upper region of the reactor cavity. With the inclusion of the shield and modifications to the reactor vessel support system, the dose rates above the closure head were reduced by a factor of approximaterly 10/sup 4/.

• Research Organization: Oak Ridge National Lab., Tenn. (USA)
• DOE Contract Number: W-7405-ENG-26
• OSTI ID: 7283731
• Report Number(s): CONF-770401-29
• Country of Publication: United States
• Language: English

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