Magnox described

The following section highlights the problems faced the manual operator in inspecting Magnox duct welds. Subsequent sections describe the instrumentation developed to assist these inspections, illustrated with exEunples. 

Jones and Bolton have provided a detailed description of the approach employed by Magnox Electric for developing trend curves describing the DDR of Magnox RPVs. The authors stress that the advantage of the physically-based approach is that the trend curves underpinned in this way can be used with confidence when limited extrapolation is required into areas of neutron dose, dose rate or irradiation temperature which are not specifically covered by the surveillance database. 

Evidently, throughout all these processes the isotopic composition of uranium remains in its natural abundance form, that is, containing 0.72% of U. Uranium of this composition is suitable for use as nuclear fuel in reactors that operate with heavy water (DjO) such as CANDU reactors or graphite (such as the old Magnox reactors) as the moderator for slowing neutrons. In this case, the UO2 is ground and sintered to form pellets that will be placed in fuel elements (see Chapter 2 for analytical procedures to characterize these pellets). As an example. Frame 1.4 describes the process used in India for production of UO2 powder, pellets, and fuel elements as an example of the processes in the UCF. 

A variety of fuel elanents are used for different types of reactors, but there are some common features. In most conunercial nnclear power plants (BWR [boiling water reactors] and PWR [pressurized water reactors] that are called in Russian VVER), the pellets are inserted into rods or tubes (usually zirconium alloys) that provide a barrier to prevent escape of fission products, the tubes or rods are arranged in bundles that are loaded into the reactor core. Usually a number of short rods are inserted into the sealed tube and held in place by a spring as described earlier. In some cases, like advanced gas cooled reactors (AGR), peUets are inserted into short narrow steel pins. Magnox reactors use magnesium alloys (usually with aluminum) rather the zirconium alloys. The fuel in some advanced reactors (TRISO) is in the form of microfuel particles with a UO2 (or UC (uranium carbide)) core surrounded by layers of pyrolytic carbon and... 

The general design features of the magnox line of reactors will be illustrated by describing the last of the series to be constructed in the United Kingdom, the twin-reactor 1180-MWe station at Wylfa Head, North Wales. The Wylfa station commenced generation in January 1971. 

Status of nuclear power and decontamination studies in the UK is described. Commercial operation of Sizewell Unit B is planned to begin in early 1994. The Nuclear Electric strategy for the development of nuclear power is to pursue the twin Sizewell Unit C station as the next step. The Berkeley Magnox station has been permanently shutdown. At Berkeley, there are eight boilers on each reactor. Because of the massive size and volume of Magnox boilers, decontamination studies focused on tests with cheap and simple reagents formic acid was chosen due to the results of these studies. 

---