Reactor pressure vessel countries

Abstract This chapter describes the surveillance database of the Western pressurized water reactor (PWR) reactor pressure vessel (RPV) beltline materials obtained from US, French and Japanese nuclear power plants (NPPs) and those from other countries, together with an overview of the characteristics of PWR RPVs. Trends of surveillance data which will be obtained in the near future and the possibility of new data from reconstituted and miniature specimen techniques are presented. 

Development work for prestressed concrete reactor structures has been proceeding in the United States for the past several years. A wide background was already in existence in this country on prestressed concrete technology related to large tanks and beam structures. Two scale models of such reactor pressure vessels have been tested at General Atomic as part of a USAEC program for High-Temperature Gas-Cooled Reactors. 

Perhaps most ingenuity has been exercised in the provision of heat removal systems from the containment. Heat can be removed either through the walls of the containment itself or by means of a heat exchanger arrangement. An example would have condensing surfaces within the containment, to condense steam released from the reactor pressure vessel, and cooled by water circulating by natural convection to an air cooler. The latter system allows the use of a full double containment as is required in some countries. 

Despite this favorable record, the further development of nuclear power is greatly handicapped in many countries because of public concern over the radioactive products arising in the course of plant operation and the consequences of their possible release to the environment. Energy generation from the neutron-induced fission of heavy atoms is inevitably accompanied by the formation of radioactive nuclides. This is, first of all, the direct consequence of nuclear fission, which leads initially to fission products that are unstable due to an excess of neutrons in the newly formed nuclei. These products are transformed by a sequence of p decays (mainly with associated y emission) to stable end products. Moreover, neutron capture in the heavy atoms of the fuel results in the buildup of nuclei which are heavier than those of the starting element (uranium, plutonium) and which mostly decay — in part, with very long halflives — by a emission. Finally, from elements present in structural and cladding materials, as well as in the coolant, its additives and impurities, additional radionuclides are formed, induced by neutron capture reactions which take place in the intense neutron field inside the reactor pressure vessel. 

One reason this design was adopted was due to reasons of transport. The Soviet Union was a vast country, and their preference was for a design where the components could be readily transported by rail. The RBMK did not have a massive reactor pressure vessel like the BWR or PWR designs. Hence, the RBMK could be built... 

Unlike the known designs of integral reactors being under development in many countries where either steam or steam-gas pressurizer is applied, the integral reactors developed by RDIPE use a gas pressurizer. Selection of such solution was motivated by several reasons, firstly, the intention to simplify and, consequently, enhance safety of the primary circuit pressure compensation system by elimination of heaters and sprinkler system. Secondly, this approach is based on our 40-year experience in designing and operation of ship-mounted NSSS with gas pressurizers in the primary circuit. It should be pointed out, however, that in the previous cases the pressurizes wee placed outside the reactor vessel. 

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