Hydrogenous moderator layer

Y. Oka and T. Jevremovic, Negative Void Reactivity in Large Fast Breeder Reactors with Hydrogeneous Moderator Layer, AnnaA of Nuclear Energy, Vol. 23, 1105-1115 (1996)... 

In this section, the effectiveness of the hydrogenous moderator layer in reducing the coolant void reactivity is explained. Its influence on breeding capability is also studied. The neutron spectra with and without the layer are analyzed and compared. Two different coolants, steam (water) and liquid sodium, are considered. The hydrogen leakage from the layer during normal operation and accidental conditions are also studied. 

The hydrogenous moderator layers in the blanket assemblies were shown to be effective in reducing the coolant void reactivity. The fuel rod design method and an... 

Y. Oka, T. Jevremovic and S. Koshizuka, Negative Coolant Void Reactivity in Large FBRs with Hydrogeneous Moderator Layers, Proc. ANS Topical Meeting on Advances in Reactor Physics, Knoxville, TN, USA, April 11-15, 1994, 419 28 (1994)... 

Reaction with cold water is of moderate vigour, but violent with hot water, and the liberated hydrogen may ignite [1], The powdered metal reacts explosively with water [2], The reactivity of lithium and other alkali metals with various forms of water has been discussed in detail. Prolonged contact with steam forms a thermally insulating layer which promotes overheating of the metal and may lead to a subsequent explosion as the insulating layer breaks up [3],... 

Adsorption of carboxylic acids, alcohols and amine on steel surfaces takes place by hydrogen-bonding of monomeric molecules to the oxide and hydroxide layers on the surface. Aliphatic amines, alcohols, and acids have also proved to be especially suitable for build-up of anti-wear protective layers, and greatly reduce the friction coefficient. Adsorbed and chemisorbed films are very effective in reducing friction and mild wear under moderate rubbing however, they fail fairly rapidly under severe rubbing conditions and therefore are not very effective in preventing wear and seizure. 

Fig. 3. (a) Schematic of the thin film target for the d/xt formation measurements consisting of the emission, the moderation and the reaction layers, which are prepared by rapidly freezing hydrogen isotopes on the gold foils (not shown) held in vacuum at 3.5 K. [13] The layer thickness (3.43 mg-cm-2, 96 pg-cm-2, and 21 pg-cm-2, respectively) were measured off-line via a particle energy loss (see Fig. 5) (b) Measured Si energy spectra with prompt (I t > 0.02 ps) and delayed (II t > 1.5 ps) time cuts. Fusion in DS reaction layer is separated from that in US D2 due to the pf TOF across the vacuum... 

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