Patent Number: 052672832
Section: description

SPECIFIC DESCRIPTION In FIGS. 1 and 2 of the drawing, we have shown a reactor containment vessel 1 enclosing the reactor core of a boiling-water reactor, for example, which is surrounded by an annular structure 2 to define an annular space 3 extending substantially all around the containment. Adjacent the structure 2 is an auxiliary apparatus building 4 and, spaced from the latter, a chimney or stack 5 opening into the atmosphere. Both in the embodiment of FIG. 1 and in the embodiment of FIG. 2, a system 6 is provided for depressurization of the containment vessel 1. In addition, a system 7 is provided for the emergency evacuation of the space 3 and for maintaining a subatmospheric pressure therein in the case of design-exceeding events involving melting of the core. The latter system 7 comprises a blower system 8 which may include a plurality of parallel blowers for redundancy purposes or to generate the necessary evacuation flow, these blowers discharging into the chimney or stack 5. As represented by the line 20, the atmosphere wherein building 4 is also vented through the stack 5. The various lines and flow directions carrying the discharge gases to the stack are shown in heavy lines and with arrows. The pressure-relief system 6, for venting the pressure in the containment 1, comprises a metal-fiber filter 9 and a molecular sieve 10 downstream thereof, the molecular sieve trapping any radioactive gases, such as fission products, which may pass the metal-fiber filter. The emergency filter of the evacuation system 7 also includes metal-fiber filters 11 and molecular sieves 12 downstream thereof as can be seen from FIG. 1. In the embodiment of FIG. 2, an emergency filter comprises not only the metal-fiber filter 11 and the molecular sieve 12 downstream thereof, but a suspended-matter filter 13 and an active-coal filter 12 in succession. In both embodiments, pluralities of the filter assemblies 11, 12 or 11, 12, 13, 14 are connected in parallel. In the embodiment of FIG. 2, moreover, at the downstream side of each filter assembly, a further suspended-matter filter 15 is provided. The filter capacities of the aerosol filters 11, 13, 15 can be stepped. In the embodiments of FIGS. 1 and 2, in which both systems 6 and 7 have metal-fiber filters and molecular sieves, these can be provided as modular units which can be interchanged for the two systems and provided in as great or small a number as required. The filter units can include other components such as missed separators, droplet separators and heaters as the design requirements dictate.