Refueling Equipment

The British and French natural uranium gas-cooled reactors have been designed for on-load refueling. This has resulted from the small excess reactivity available in natural uranium systems and, therefore, the frequent plant shutdown that would be required if new fuel additions could not be made while the plant was in operation. The refueling machines that have been developed for this purpose are large (49) and represent a significant fraction of the plant cost. 

In the case of the slightly enriched AGR reactor, on-stream refueling has been chosen for the first power plants (5). 

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In the United States, CNG s initial use is in captive, centrally refueled fleets which require limited range, such as deHvery vans, taxis, or school buses. Such vehicle fleets can afford the capital cost of refueling equipment and can tolerate the slightly longer refueling times. Many utiHty companies, such as Brooklyn Union Gas (New York), have purchased CNG vehicles as a way of encouraging the development of this fuel. AH three domestic automobile manufacturers offer CNG vehicles for sale. 

For pictures of hydrogen powered automobiles, refueling equipment and a hydrogen fuel cell buss and other information on the use of hydrogen as a fuel. 

To minimize reactor shutdown time, the overall system configuration is selected on the basis of time-motion studies and the refueling interval requirement. System configuration studies include tradeoff studies such as leaving parts of the refueling machine in the vessel during operation (FFTF) versus full removal of the refueling equipment (CRBR). 

Turntable Support structure Support CCPs and maintain Subcriticality of fuel assemblies by physical separation Support storage vessel, guard tank, and interfacing refueling equipment loads and transfer these loads to the vault concrete... 

Small reactors without on-site refuelling incorporate increased refuelling interval (from 5 to 30 years and more), consistent with plant economy and considerations of energy security. Both front-end and back-end fuel cycle services are assumed to be completely outsourced for such reactors, i.e., they are either factory fabricated and fuelled or undergo a once-at-a-time core reloading performed at the site by a dedicated service team provided by the vendor of the fuel or the reactor itself such team is assumed to bring in and take away the fresh and spent fuel load and the refuelling equipment. 

Has a long (many years) whole-core refuelling interval with a potential for refuelling equipment to be brought to the site by the refuelling team, or with entire reactor module change-out. 

For the international community, small reactors without on-site refuelling could offer possibly increased non-proliferation assurances by somewhat diminishing the incentive for their users to emplace indigenous nuclear fuel cycle infrastructures. Other factors contributing to such increased assurances could be the absence of refuelling equipment on the site during plant operation and elimination of the on-site fresh and spent fuel repositories. 

Whole core refuelling, which is performed at the end of each fuel lifetime the discharge of fuel is performed cassette-by-cassette fresh fuel is loaded as a single cartridge with the help of a refuelling equipment set common to all reactor modules within a given NPP ... 

Such shared systems and equipment include the refuelling equipment, the coolant intake equipment, the equipment for conveying coolant to the reactors at the initial filling, etc. and their contribution to the specific capital construction costs of an NPP will decrease correspondingly. 

Any attempt to divert fuel during reactor operation would require shutting down the reactor and commencement of heavy lift operations. The former would be detectable through the provision of monitoring and the latter could be observed by means of overhead reconnaissance. The long core lifetime limits the availability of refuelling equipment at the site to only a relatively short interval every 15 or 20 years. 

Provision for core cassette refuelling using refuelling equipment including a heavy lift crane that is brought to the site only at the end of the core lifetime and is removed from the site following refuelling ... 

The additional strategies to counteract the capital cost ( /kW(e)) escalation for small battery reactors is based on simpler reactor control and refuelling systems, factory mass fabrication, modular construction and rapid start-up of a pre-licensed plant. For example, the STAR-H2 design eliminates primary pumps and on-site refuelling equipment. 

It is expected that all fuel cassette shipments and used cassette returns would be conducted by itinerate regional centre refuelling teams who will bring the replacement cassette and the refuelling equipment with them, perform the refuelling operations, and take the refuelling equipment away with the spent cassette. No refuelling equipment would, therefore, remain at the battery heat source plant site (see Fig. XXIV-12). 

The LSPR is a factory fabricated and fuelled reactor designed for operation without on-site refuelling. During the whole period of reactor operation and transportation to and from the site, the reactor vessel is always closed (sealed) and the fuel is confined in the vessel. Because of very small operation reactivity margin in the core, the fuel inside the reactor vessel cannot be removed and fertile materials cannot be inserted in the reactor to produce fissile materials. No refuelling equipment is provided in the reactor or at the site during the whole period of reactor operation, including its transportation to and from the site. 

USNRC Information Notice 94-13, Unanticipated and unintended movement of fuel assemblies and other components due to improper operation of refueling equipment, Februaiy 22,1994. 

Problems encountered in the operation of the magnox stations included (a) early difficulties with the complex refuelling equipment, (b) vibration of components due to gas glow, and (c) corrosion of gas circuit steel components in the carbon dioxide atmosphere. The last of these has proved the most serious, since it has led to the imposition of a reduction in power output in order to maintain the gas outlet temperature at a value where the corrosion rate is low enough to assure an economic life for the reactor. The problem is confined to small components, such as nuts and bolts made from low-silicon mild steel, and there is no danger to the more massive components of the pressure circuit. 

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