Decay heat removal by sodium-air heat exchangers

In fast reactors, decay heat is removed by special sodium circuits equipped with a sodium-sodium heat exchanger immersed in the hot pool and with a sodium-air heat exchanger. Studies carried out by the Ansaldo company in association with ENEA have shown that both the sodium and the air circuits can have natural circulation. This option, however, requires the circuit components to be specially designed in order to cope with the large thermal gradients which occur and to ensure that natural circulation begins and is satisfactorily maintained without risk of sodium solidification. The Belleli company has made a decisive contribution to these results by constructing the sodium-air heat exchangers for the ultimate heat sink circuit of the Creys-Malville plant and four heat exchangers for the PEC reactor. (author)