Negative void reactivity in a large liquid-metal fast breeder reactor with hydrogenous moderator (ZrH[sub 1. 7]) layers

Journal Article · Fri Jul 01 04:00:00 EDT 1994 · Nuclear Technology; (United States)

OSTI ID:7230637

Oka, Yoshiaki; Jevremovic, T; Koshizuka, Seiichi ^[1]

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1. Univ. of Tokyo, Ibaraki (Japan). Nuclear Engineering Research Lab.

Placing a thin hydrogenous moderator (ZrH[sub 1.7]) layer between the seed and the blanket is very effective in reducing the sodium void reactivity of a liquid-metal fast breeder reactor (LMFBR). The void reactivity reduction is attributed to the decrease in neutron production and increase in neutron absorption in the blanket at voiding due to the slowing down of fast neutrons in the layer. This dominates the whole core neutron balance. The fixed hydrogenous layer concept is much more effective than the conventional uniform introduction of such moderator in a core. Furthermore, it does not seriously deteriorate the breeding capability. For realizing the negative sodium void reactivity in a large-sized core, the seeds should be divided by blankets with the layers. The conceptual design of a nonflat LMFBR core is presented for demonstrating the effectiveness of the layer. Negative void reactivity is realized in a radially heterogeneous core of 1,000-MW(electric) class output. The active core is 2.9 m high. It is much taller than the conventional LMFBR core, which is [approximately]1 m high. A wide pitch-to-fuel diameter ratio was chosen so as not to increase the pressure drop in the core. The compound system doubling time is 12.5 yr.

• OSTI ID: 7230637
• Journal Information: Nuclear Technology; (United States), Journal Name: Nuclear Technology; (United States) Vol. 107:1; ISSN 0029-5450; ISSN NUTYBB
• Country of Publication: United States
• Language: English

Related Subjects

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BREEDER REACTORS
BREEDING BLANKETS
EPITHERMAL REACTORS
FAST REACTORS
FBR TYPE REACTORS
HYDRIDES
HYDROGEN COMPOUNDS
LIQUID METAL COOLED REACTORS
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REACTIVITY COEFFICIENTS
REACTOR COMPONENTS
REACTOR CORES
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SAFETY
TRANSITION ELEMENT COMPOUNDS
VOID COEFFICIENT
ZIRCONIUM COMPOUNDS
ZIRCONIUM HYDRIDES