Critical Reflections about Doel3 & Tihange2

Integrity reactor vessels Doel 3 and Tihange 2

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Figure 19: Solubility of hydrogen in steel in terms of temperature and pressure [ 11 ]

inwards, the internal part of the ingot will be enriched with impurities and alloying elements, while the outside part will be poor in alloying elements, due to the higher solubility of the alloying ele- ments in the liquid phase. During forging, the parts of the ingot with the high segregation areas have been removed by cutting off the bottom and the top from the ingot and in a next step the centre part of the ingot which also contain high segregation areas has been pierced out. From the resulting hollow cylinder, the reactor vessel shell has been forged. After forging and cooling until room temperature, the inner and the outer wall will be machined by cutting away about 40 mm at each side on a lathe. Available amount of hydrogen in case of a concentration gradient. As temperature gradients during cooling of the ingot occur, some gradient of hydrogen concentration will appear. As data lacks for a profound analysis, a linearised model will be used. The model will be developed such that the gradient of hydrogen will be "a bad case", i.e. a refined analysis will probably result in a lower hydrogen concentration gradient. To estimate the hydrogen concentration gradient, four steps have to be followed. The first step is to localize the future shell in the ingot. Second, the temperature drop over the ingot during

R.Boonen & J.Peirs

May 18, 2017