Steam ingress reactivity effects in the GCFR

Technical Report · Sun Jul 01 04:00:00 EDT 1979

DOI:https://doi.org/10.2172/6078138· OSTI ID:6078138

Hess, A. L.; Hamilton, C. J.

Because of the higher pressure on the steam side of the steam generator in the gas-cooled fast breeder reactor (GCFR), the potential exists for steam-generator tube leaks or ruptures which might introduce water vapor into the primary coolant and thence into the core region. This potential for core steam ingress requires that a satisfactory understanding of the reactivity effects due to various concentrations of hydrogeneous material in the core be achieved. The reactivity effects resulting from an increase in hydrogen density are two-fold: a decrease in neutron leakage from the core, and a moderation of the neutron energy spectrum. The leakage effect is always positive and is predominant in smaller systems with attendant higher leakage fractions. Also, the cold-to-hot operating core temperature transition produces a negative reactivity effect (to a large extent due to the Doppler effect on absorption in U-238), which is substantially increased by progressive softening of the spectrum due to hydrogen addition. Research programs studying these reactivity effects are described.

• Research Organization: General Atomic Co., San Diego, CA (USA)
• DOE Contract Number: EY-76-C-03-0167-023
• OSTI ID: 6078138
• Report Number(s): GA-A-15514
• Country of Publication: United States
• Language: English

Related Subjects

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
210500* -- Power Reactors
Breeding
BOILERS
BREEDER REACTORS
EPITHERMAL REACTORS
FAST REACTORS
FBR TYPE REACTORS
GAS COOLED REACTORS
GCFR REACTOR
GCFR TYPE REACTORS
HELIUM COOLED REACTORS
LEAKS
REACTIVITY COEFFICIENTS
REACTIVITY WORTHS
REACTORS
STEAM
STEAM GENERATORS
VAPOR GENERATORS