15.69. In the safe integral reactor (SIR), the entire PWR primary sys­tem, including the steam generator, is enclosed within the steel reactor vessel. Thus, we have a unit steam generating package with no possibility of a LOCA. In a sense, the characteristics of a PWR are combined with some BWR technology. Passive safety systems are included, such as safety injection accumulators and blowdown pressure suppression tanks. The ref­erence SIR design has an electrical generating capacity of 320 MW, al­though an extended SIR of 400 MW(el) is an option. Construction of a lead unit at Winfrith in the United Kingdom has been proposed.