MARITIME GAS-COOLED REACTOR PROGRAM QUARTERLY PROGRESS REPORT FOR THE PERIOD ENDING MARCH 31, 1960
Reactor design activities continued with emphasis on fuel elements. Two fuel-element concepts were chosen for development. Both were based on the concept of 19-rod clusters with spiral spacers. One is comprised of 1/4- in.diameter rods with pure UO/sub 2/ fuel bodies whereas the other uses 3/8-in.- diameter rods with UO/sub 2/-BeO fuel bodies. A program is under way to develop methods for the fabrication of fuel rods. Two points receiving most attention are the method of attaching the spiral spacers and the creepshrink process for controlled collapse of the cladding on the fuel bodies. Tests are being carried out to determine the internal pressures that will cause bursting of the cladding tubes at various tcmperatures. A mock-up of a part of a semi-homogeneous graphite plate-type fuel element with nickel-clad fuel rods was tested for approximately 1000 hr at a surface temperature of 1500 deg F. The initial visual examination showed no signs of damage. Tests are continuing on the heat-transfer characteristics of high-pressure helium in tube bundles. A study of the thermodynamic properties of helium at high pressures was completed. Studies were carried out to determine the particular arrangement that satisfies the requirements of accessibility, compactness, low-pressure loss in the ducting, and acceptable thermal stress. A method was developed for analysis of the dynamics of the MGCR power plant by digital computer. Calculations made to date indicate that the system is inherently stable. A start-up accident brought about by too much rod withdrawal was analyzed. It was found that the excursion could be terminaied by insertion of the control rods at normal speeds. Analysis of a loss- of-coolant accident indicates that the fuel elements can lose heat to the moderator by radiation for approximately 1 hr before it is necessary to initiate emergency cooling measures to avoid dangerous temperatures on the fuel cladding. Reactor physics work included completion of a survey of the effect of the independent variables: core size, reflector material, void volume, and fuel enrichment on total power cost. Studies were made of the effect of core structure on power cost. The effects were calculated of four different metallic fuel-element shrouds and one alumina sleeve design. Calculated control-rod requirements indicate a need for conirol of 49% reactivity to cover the range of conditions from hot to cold and flooded. Flux contours were calculated in three different degrees of detail. By using combinations of these distributions, it is possible to obtain approximate flux at any point in the core. The generation of tritium by n, alpha reaction in the BeO moderator was calculated. Methods of calculating criticality are being checked against critical experiments at Livermore and the NTS "Hot Box," Materials work is continuing with development of techniques for fabrication of ceramic fuel bodies. Specimens of UO/sub 2/Al/sub 2/O/sub 3/ bodies were irradiated to 9000 Mwd/t. Investigation is continuing to establish the best means of fabrication of beryllia shapes for the moderator and reflector. Tests are continuing to establish creep-rupture and fatigue strength of structural metals in high-temperature helium. (For preceding period see GA- 1195.) (auth)
- Research Organization:
- General Atomic Div., General Dynamics Corp., San Diego, Calif.; General Dynamics Corp. Electric Boat Div., Groton, Conn.
- DOE Contract Number:
- AT(04-3)-187
- NSA Number:
- NSA-15-008341
- OSTI ID:
- 4106856
- Report Number(s):
- GA-1259
- Resource Relation:
- Other Information: Orig. Receipt Date: 31-DEC-61
- Country of Publication:
- United States
- Language:
- English
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