Patent Number: 044951477
Section: claims

1. Heat retarding closure system, for partitions having pressure relief openings formed therein, in nuclear reactor buildings where main coolant nozzles of a reactor pressure vessel penetrate a biological shield, comprising blowout inserts in the form of closure elements having a side facing the reactor, a side facing away from the reactor and anchors for holding said closure elements, said blowout inserts being pushable out of said anchors by an overpressure in a given pressure difference direction on said side facing the reactor, and an outer sealing blowout skin, said blowout inserts being in the form of heat-retarding cassette inserts having a front surface at said side facing away from the reactor with a peripheral shearing edge formed thereon resting against said blowout skin, said blowout skin having a given thickness in said given pressure difference direction, said blowout skin being sheared off by said shearing edge of said cassette insert and said cassette insert being pushed out of said anchors when a given pressure difference is reached, said anchors being in the form of a partition seat having an outside and an inside and said partition seat and blowout insert being widened from the inside to the outside. 2. Closure system according to claim 1, wherein said cassette insert contains retarding material in the form of mineral fibers. 3. Closure system according to claim 1, wherein said cassette insert is formed of metal and includes layered and mutually spaced apart retarding foils in the interior thereof for retarding pressure in said pressure difference direction, said foils forming retarding cells. 4. Closure system according to claim 1, wherein said blowout insert and partition seat are conically shaped from the inside to the outside. 5. Closure system according to claim 1, wherein said blowout insert and partition seat are truncated pyramoidally shaped from the inside to the outside. 6. Closure system according to claim 1, wherein said cassette insert has a partition area and said blowout skin is in the form of a glass blowout pane being clamped and sealed to said partition area. 7. Closure system according to claim 1, wherein said blowout skin is a metallic blowout foil. 8. Closure system according to claim 1, wherein said cassette insert includes a peripheral sheet metal envelope having a front surface and said shearing edge projects from said front surface of said envelope. 9. Closure system according to claim 3, wherein one of said foils is a front foil forming said shearing edge, said front foil having a doubly chamfered rim being substantially V-shaped and having a relatively greater thickness than the others of said foils.