NUCLEAR SUPERHEAT DEVELOPMENT PROGRAM. Fifth Quarterly Progress Report, July-September, 1960

Technical Report · Tue Oct 31 04:00:00 EST 1961

OSTI ID:4080645

Study of the NUSU superheater-reactor reference design criteria was continued with the investigation of alternate fuel-element concepts and of alternate reactor plant cycles. The principal design effont centered around a multiple-tube fuel-element concept. Two possible fuel-element configurations are under study, differing primarily in the heat-transfer surface areas and in the power split between the boiler and superheater surfaces. In this connection two potential plant cycles were investigated. The large water passages between fuel elements in the superheater region make possible the consideration of natural circulation of the water coolant. An alternate reactor arrangement is presented which uses natural circuiation in the superheater region and forced circuiation in the boiler region. The study of the effect on shutdown cooling of the natural circuiation of steam within the double-annular fuel element was completed. Critical expeniments performed thus fur provided information on critical size as a function of geometry, of water height, and of simultated steam void content in cores made up of rodtype boiler fuel elements, of 1.85% enrichment, and of rodtype superheater fuel elements of the 3.41% U/sup 235/ enrichment. The relative effects of various cadmium and boron-stainless steel control blades were also compared. The fuel-element design was completed, and the apparatus for preparing the double-annular fuel elements by vibratory compaction was set up and tested. Achievement of 85% of theoretical density on a routine basis appeared to be feasible. The particle-size distribution of the fused powder used in the compaction process was not fully optimized for maximum utilization of the incoming material. Further study is in progress to improve the yield from incoming UO/sub 2/ fused powder. Additional work was done on the theory and analysis of critical configurations. The previous calculations were extended to two-region slab reactors using rodtype elements of the boiler and superheater types now on hand for the NUSU critical experiments. In addition, calculations were performed on the configurations to be used in critical experiments with double-annular elements. An enrichment of 2.55 wt.% U/sup 235/ was selected to ensure criticality of the tightest lattice contemplated. The checkout operation of the steam-purity test loop was completed, with steam qualities ranging from 99.5 to over 99.9%. Background total solids entrained in the steam ranged from 2 to 3 ppm. Several minor modifications were made in the loop. The first phase of gravity-separation tests in the highpressure steam separator loop at Chattanooga was completed. It appeared that the gravitational steam separation is a function of recirculation ratio, of pressure, and of steam release rate. A height of 4 to 5 ft above the steam-water interface appeared to be adequate for all conditions encountered in the integral boilersuperheater reactor designs which were under consideration. This disengagement height increased with the depth of submersion of the inlet nozzle for the steam-water mixture. (auth)

• Research Organization: Combustion Engineering, Inc., Windsor, Conn.; General Nuclear Engineering Corp., Dunedin, Fla.
• NSA Number: NSA-15-012559
• OSTI ID: 4080645
• Report Number(s): GNEC-149
• Country of Publication: United States
• Language: English

Related Subjects

BOILING
CONFIGURATION
CONVECTION
COOLANT LOOPS
COOLING
CRITICALITY
ENRICHMENT
FUEL ELEMENTS
HEAT TRANSFER
LEVELS
NUSU
REACTOR TECHNOLOGY
REACTORS
RODS
SHUTDOWN
SUPERHEATING
SURFACES
TUBES
URANIUM 235
ZONES