TEMPERATURE TRANSIENT IN NET SHIELDING BLANKET SEGMENTS DURING MAINTENANCE

The thermal behaviour of the NET Shielding Blanket segments after shutdown as a consequence of the afterheat sources has been analyzed by mean of a computer code, DELFINE, able to treat 2D geometry problems. Possible scenarios immediately after shutdown and during maintenance have been envisaged and analyzed from the point of view of the maximum reached temperature. In all cases it has been found that the temperature remains within acceptable limits for the integrity of the metallic structures. On the other hand, after cutting the cooling system, the temperature quickly tends to get over the operation temperature that, for the Shielding Blanket is assumed to be 100°C. This effect could increase the tritium outgassing up to unacceptable levels. © 1990.