Containment, fast reactors

Nuclear and magneto-hydrodynamic electric power generation systems have been produced on a scale which could lead to industrial production, but to-date technical problems, mainly connected with corrosion of the containing materials, has hampered full-scale development. In the case of nuclear power, the proposed fast reactor, which uses fast neutron fission in a small nuclear fuel element, by comparison with fuel rods in thermal neutron reactors, requires a more rapid heat removal than is possible by water cooling, and a liquid sodium-potassium alloy has been used in the development of a near-industrial generator. The fuel container is a vanadium sheath with a niobium outer cladding, since this has a low fast neutron capture cross-section and a low rate of corrosion by the liquid metal coolant. The liquid metal coolant is transported from the fuel to the turbine generating the electric power in stainless steel... 

Pu. The isotope Pu results from neutron capture in followed by two beta decays. It is the principal isotopic constituent of plutonium formed by the irradiation of low-enrichment uranium. It is the principal flssile corrstituent in plutonium fuel used in thermal and fast reactors. Pu alpha decays, with a half-life of 24,400 years, to form the U parent of the An+3 decay series discussed in Chap. 5. Relatively pure Pu can be made by the short-term low-exposure inadiation of natural uranium. Plutonium containing more than 99 percent Pu results from the irradiation of uranium at fuel exposures of less than 0.7 MWd/kg [K2]. Because of the hi ... 

The thermal-neutron absorption cross section of natural boron, which contains 19.61 percent is 759 b, whereas that of separated B is 3837 b. Thus, enriched B is useful in applications where the highest volumetric rate of neutron absorption is wanted. Examples are compact shielding for thermal neutrons and control rods for fast reactors. 

Due to the tailored properties of liquid phase sintered silicon carbide (LPSSiC) it is used as dewatering elements in the paper machinery and as rings for highly stressed gas seals. It is a price competitive alternative to silicon nitride materials and outperforms alumina and tungsten carbide materials. In addition, LPSSiC is proposed as neutral matrix in ceramic matrix composites containing plutonium to burn the world s stockpiles of military plutonium in thermal or fast reactors [278]. 

The ultimate objective for fast reactors has always been to maximise the utilisation of the natural uranium resource and in common with the main development programmes world wide, EFR has pursued the sodium coolant technology. The safety approach recognises the differing requirements of a sodium cooled fast reactor core compared to the established water and gas cooled thermal reactors which has resulted in a different balance between prevention and mitigation with consequences for the shutdown, decay heat removal and containment systems. 

The transport of the fuel aerosols and fission products from the cover gas to the various cells of the reactor building and to the environment is calculated with the CONTAIN-LMR. Papers on this code were presented during the IWGFR TCM [ref 4] on "Evaluation of Radioactive Materials Release and Sodium Fires in Fast Reactors". 

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