Pressurized water reactors component design

A variety of nuclear reactor designs is possible using different combinations of components and process features for different purposes (see Nuclear REACTORS, reactor types). Two versions of the lightwater reactors were favored the pressurized water reactor (PWR) and the boiling water reactor (BWR). Each requites enrichment of uranium in U. To assure safety, careful control of coolant conditions is requited (see Nuclearreactors, water CHEMISTRY OF LIGHTWATER REACTORS NuCLEAR REACTORS, SAFETY IN NUCLEAR FACILITIES). 

SMART (System-integrated Modular Advanced ReacTor) is an advanced integral PWR(Pressurized Water Reactor) tihat produces 330MWt at fiill power. Major primary components are housed within a single pressure vessel. New, advanced and innovative features are incorporated in the design to provide the reactor with significant enhancements in safety, reliability, performance, and operability. Major design and safety characteristics of SMART can be summarized as follows ... 

Because the HTR-10 test reactor is designed on the inherent safety philosophy, safety classifications of systems and components departure from the way it is done for water cooled power reactors For example, primary pressure boundary is defined to the first isolation valve Steam generator tubes are classified as Class II component Diesel generators are not required to be as highly qualified as those used for large water cooled power reactors, since no systems or components with large power demand would require an immediate start of the diesel engines at a plant black-out accident... 

Hafnium-free zirconium alloys containing tin or niobium are used for tubing to hold uranium oxide fuel pellets inside water-cooled nuclear reactors. Zirconium —niobium alloys are used for pressure tubes and stmctural components in Canadian, the former USSR, and Germany reactor designs. 

As an example of intrinsic safety features, consider the HYLIFE design. The HYLIFE reactor room has no external walls or roof it is surrounded by other rooms and covered with a crane loft. The reactor room contains an inert gas (no air). The entire Li inventory can be drained in minutes in case of an air leak into the room such a leak would require hours before lithium combustion is possible. There are no water or steam components in the reactor room, and all concrete is steel lined. The lithium loop is everywhere sub-atmospheric pressure (1 Pa to 80 kPa or 10 to 620 Torr) hence, small leaks will be inward. Large leaks will fall on a sloped floor that drains to tall narrow tanks containing hollow graphite spheres that would float above spilled lithium. Additional inert gas injection capability will be available in these areas. 

The pressurizer is designed as a cylindrical vessel, its cover being tiie central cover of the reactor vessel. The pressurizer is separated into two cavities central where the "water-gas" phase separation level is set in all power modes of operation, and annular peripheral cavity housing a heat exchanger connected to NSSS component cooling system. The annular cavity is connected by pipelines with upper part of the reactor and with the central cavity. Inner surface of cylindrical... 

The WWER RPVs (as well as all other components) must be transportable by land, i.e. by train and/or by road. This requirement has some very important consequences on vessel design, such as a smaller pressure vessel diameter, which results in a smaller water gap thickness and thus a higher neutron flux on the reactor vessel wall surrounding the core and, therefore, requirements for materials with high resistance... 

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