Fast reactor containment system

The lead-cooled fast reactor (LFR) system is also under development in Generation rV framework. It has to be pointed out that there is no industrial experience of lead aUoy-cooled technology except that fi om the Soviet Union submarine program. But many concepts exist worldwide for example, the MYRRHA (Multipurpose hYbrid Research Reactor for High-tech Applications) reactor is developed by the Belgian Nuclear Research Center SCK-CEN in collaboration with international partners. MYRRHA is conceived as an accelerator-driven system able to operate in subcritical and critical modes. It contains a proton accelerator of600 MeV, a spallation target, and... 

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... 

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. 

Transfer system. The principal system used to transfer fuel and other components to and from the reactor vessel is the closed loop ex-vessel machine (CLEM) shown in Fig. A.2. The CLEM loads all components into the reactor vessel and removes all components from the reactor vessel and operates only when the reactor is shutdown. Under most conditions, CLEM moves a core component pot (CCP) that contains the fresh or SNF fuel to and from the reactor vessel. In a fast reactor, the core power density is very high thus, there is significant decay heat in each SNF assembly immediately after reactor shutdown. To prevent fuel failure from overheating, the SNF is kept in sodium at all times to ensure effective cooling. This is accomplished by transferring each fuel assembly in its own pot of sodium—the CCP. CLEM is also used to transfer a variety of other components within the reactor containment. 

Towards the preparation of radioactive source for the actmty transport and deposition studies, method of preparation of electrodeposited source for 2 was standardised. A scale model of an experimental setup for wetbed submerged gravel bed SCTubber has been made for assessment ofits performance and mrploring the fearibility ofuse of similar system in fast breeder reactor containment venting jq plications. 

Cooling of the reactor core when the plant is in the shutdown condition or following the occurrence of abnormal events is reliably assured by making use of the natural force of gravity. Provision of a large water inventory inside the reactor pressure vessel as well as of a large source of water inside the containment makes active, fast-response safety equipment, pumps and electric power unnecessary in the event of disturbances in the reactor coolant system. 

A possibility that many experts see, even though it is a longterm possibility, as may be the point of arrival of any agreements, is to oppose any possible negative effects of the spread of fast reactors with a stockpiling system of plutonium surplus in deposits put under international control—for example, of the IAEA. Indeed, the control of isolated plutonium (plutonium is found in this state once separated from the products of fission contained in the irradiated fuel) is the essential factor on which the most realistically conceivable international security system is based, according to INFCE, presupposing a recourse to fast reactors. 

According to experience from existing fast reactors and Na test facilities, leakage from Na-containing systems and components cannot be excluded. 

The major advantage of the use of two-phase catalysis is the easy separation of the catalyst and product phases. FFowever, the co-miscibility of the product and catalyst phases can be problematic. An example is given by the biphasic aqueous hydro-formylation of ethene to propanal. Firstly, the propanal formed contains water, which has to be removed by distillation. This is difficult, due to formation of azeotropic mixtures. Secondly, a significant proportion of the rhodium catalyst is extracted from the reactor with the products, which prevents its efficient recovery. Nevertheless, the reaction of ethene itself in the water-based Rh-TPPTS system is fast. It is the high solubility of water in the propanal that prevents the application of the aqueous biphasic process [5]. 

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