Reactor magnox

The Magnox reactor concept owes its origins to a design study conducted at Harwell, U.K., diuing the early 1950s. The reactor was designed with the dual role of plutonium and power production, and was known by the code word PIPPA... 

Cladding. The Magnox reactors get their name from the magnesium-aluminium alloy used to clad the fuel elements, and stainless steels are used in other gas-cooled reactors. In water reactors zirconium alloys are the favoured cladding materials. 

By the end of 1952 it was certain that a PIPPA design had been produced which could and should be built. A summary report was prepared in January 1953, and soon after approval was granted for construction of the first two Magnox reactors at Calder Hall. Before the first reactor went critical in 1956 work had started on a further two reactors at Calder Hall, and all four were at power in 1959. Construction at Chapelcross, in the southwest of Scotland, began in 1955. The fist... 

Can failures occur from time to time. The release of fission products from them depends on the temperature and type of fuel. If the fuel is uranium metal, as in the Windscale and Magnox reactors, and the can fails, the uranium will oxidise in air or C02. In laboratory experiments, the mass median aerodynamic equivalent diameter (MMAD) of the particles produced by oxidation of uranium increased from about 40 ptm when the temperature of oxidation was 600°C to 500 jum at 1000°C (Megaw et al., 1961). At high temperature, a coherent sintered oxide layer formed on the uranium and this hindered the formation of particles. 

Degradation of cladding in a water environment means that SNF from the Magnox reactors has been, and will continue to be, reprocessed at Sellafield. AGR fuel can be reprocessed or placed in long term storage. 

From the 86 streams selected as representative of Magnox reactor operational solid and mobile intermediate level wastes, 49 radionuclides were identified which are subject to detailed determination under UK Nirex requirements for radioactive ILW packages. 

W.A. Westall et al.. Determination of and Li in Magnox reactor steels. Environmental Radiochemical Analysis, RSC 10 Int. Symposium, Oxford, U.K.,13-15 September, 2006. 

APPLICATION OF THE RADIOLOGICAL HAZARD POTENTIAL (RHP) TO RADIONUCLIDES IN MAGNOX REACTOR DECOMMISSIONING... 

Magnox Reactor waste streams include a wide range of materials such as ion exchange (IX) resins, sludge, Magnox fuel element debris (FED), reactor graphite and carbon and stainless steels. Some wastes will exhibit heterogeneity and for many construction materials such as steels there will be radionuclides present which are neutron activation products of trace impurities and were un-quantified at the time of manufacture. 

DETERMINATION OF TRITIUM RADIONUCLIDE AND LITHIUM PRECURSOR IN MAGNOX REACTOR STEELS... 

Determination of Tritium Radionuclide and Lithium Precursor in Magnox Reactor Steels 139... 

The intention of this work was to measure the concentration of Li in examples of unirradiated reactor steel from which the likely activity concentration could be calculated using suitable values for the neutron flux. Calculated values could then be compared with the activities measured in examples of steel irradiated in a Magnox reactor. From this it was hoped to ascertain whether, given the concentration of Li, the activity could be reliably calculated or whether the effects of formation from ternary fission and subsequent diffusion would prevent this. Whilst the activity in activated steel was measured in a straight forward manner, the measurement of Li in steel was difficult. The conventional analytical techniques of ICP-OES and ICP-MS respectively failed to achieve an adequate detection limit, so alternative techniques were tried. SIMS was sensitive enough to detect Li but is a microscopic technique and so was prone to large uncertainties when used to predict the bulk concentration. NAA followed by radiochemical determination allowed the determination of but initially suffered interference from another activated radionuclide ( S). 

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