Breakdown protection system of modular steam generators for sodium cooled fast reactors

The emergency protection systems are assessed for 30 MW and 200 MW modular steam generators. Two emergency protection systems are envisaged for high-capacity modular steam generators, viz., systems with a separate through-flow compensating tank for each section and with a common compensating tank for several sections. The former requires a large number of flow sensors and in view of the large number of measuring points a computer is necessary for evaluation. The benefits of the design include doubling the function of section emergency protection elements, simple assembly, control and operation of the steam generator section integral with the compensating tank; in case of an accident the products of the sodium-water reaction do not pass through the compensating tank. In the latter type the compensating tank may either be of a through-flow or a compensator type. Its capacity, however, should be sufficiently high. The constraint is in that that in case of an accident occurring in one section the operation is hindered of the other sections coupled to the common compensating tank. (Z.M.)