Effects of neutron irradiation

Allen and co-workers [130] irradiated high strength and high modulus fiber at a flux of 

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Table 2. Effect of neutron irradiation on some graphite or CFC materials studied for fusion applications [12]...

In support of the development of graphite moderated reactors, an enormous amount of research has been conducted on the effects of neutron irradiation and radiolytic oxidation on the structure and properties of graphites. The essential mechanisms of these phenomena are understood and the years of research have translated into engineering codes and design practices for the safe design, construction and operation of gas-cooled reactors. 

J. Bloch, Effect of neutron irradiation of uranium-iron alloys dilute in iron, J. Nuclear Mater. 6 (1962) 203-212. 

Studies of the effect of neutron irradiation are divided into three groups slow or thermal neutrons, fission products and reactor neutrons. The slow neutrons are obtained from a radioactive source or high energy neutrons that are produced by deuterium bombardment of a beryllium target in a cyclotron and slowed down passing thru a thick paraffin wax block. The fission products in one case are produced when a desired sample is mixed or coated with uranium oxide and subsequently irradiated with slow neutrons. The capture of neutrons by U23S leads... 

R.A. Causey, K.L. Wilson, W.R. Wampler, B.L. Doyle, The effects of neutron irradiation on the trapping of tritium in graphite, Fusion Technology 19 (1991) 1585... 

Micro-Raman spectroscopy was used to characterise 4H-SiC layers grown from a variety of precursor systems.381 FTIR data were able to characterise hydrogenated amorphous silicon nitride films with embedded nanoparticles. Oxidation leads to the appearance of an Si O feature at 1070 cm 1,382 Raman spectra were used to determine the degree of micro-crystallinity of pc Si I I layers, using the intensity ratio of bands at 520 cm-1 and 480 cm-1.383 IR and Raman spectra were used to determine the effects of neutron irradiation on a-SiC H films.384 A range of a-SiCx I I and a-SiCxNy H films were studied using IR spectroscopy 385 similar experiments were carried out on a-Si i xGcx Il,F films.386... 

Hon and Bray discussed the effects of neutron irradiation damage in cubic lattices using Br SSNMR experiments on a KBr single crystal and SSNMR (as well as Li and Na) experiments on Lil, Nal, and They provided... 

Katoh et al used the linear thermal resistance model and the temperature dependent defect thermal resistance data for the composites constituents to predict the effect of neutron irradiation On temperature dependent thermal conductivity of the composites. The prediction suggested that the maximum and minimum post-irradiation through-thickness conductivity was 10-15 W/m-K at 800-1000"C for 3D architecture, and less than 5 W/m-K at <800"C for 2D architecture. 

By combining calorimetry with three-dimensional atom probe analysis, Starink and coworkers [25] examined the aging, at room-temperature, of Al-Cu-Mg-Mn alloys and found that the process is accompanied by a substantial exothermic heat evolution, whereas the only micro-structural change involved the formation of Cu-Mg co-clusters. Tatar and Zengin [26] studied the effects of neutron irradiation on the oxidation behaviour, microstructure and transformation temperatures of CuAlNiMn shape-memory alloy. They showed that irradiation... 

D R Harries, R W Nichols and C Judge,The effect of neutron irradiation on the ductile-brittle transition temperature of steels and its relevance to reactor pressure vessels. Symposium on Steels for Reactor Pressure Circuits, Iron and Steel Institute Special Report, No 69,1961,297-327. 

Y. Nishiyama, K. Onizawa, M. Suzuki, J.W. Anderegg, Y. Nagai, T. Toyama, M. Hasegawa and J. Kameda, Effects of neutron-irradiation-induced intergranular phosphorus segregation and hardening on embrittlement in reactor pressure vessel steels , Acta Mater., 2008,56,4510-4521. 

The effect of neutron irradiation on metals is mainly to increase the yield and the ultimate strength and to reduce the toughness. Helium or fission gas production within the metal matrix leads to changes in material properties and also to swelling. Swelling is particularly important in reactor control devices made of boron compounds. 

It has been recognised that decommissioning sites can be a useful source of information that is relevant to those stations that are still operational. For example, one of the key issues relevant to the safety cases for the continued operation of the steel reactor pressure vessel Magnox stations is the effects of neutron irradiation induced embrittlement. The reactor vessels at Trawsfynydd have been identified as a source of representative and highly irradiated material that can be sampled and subjected to detailed analysis to determine the actual rather than just the predicted effects of embrittlement. This has required special remotely operated equipment to be developed that is capable of reaching the base of one of the reactor vessels, which is not readily accessible and is in a high radiation area, and that can then remove and retrieve steel samples for laboratory analysis. This equipment is now being deployed successfully. 

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