HTGR Knowledge Base

Conference Article: Safety concept and design of a modular gas cooled high-temperature reactor from the viewpoint of externally generated load cases

Peters, K.; Mueller-Frank, U.; Steinwarz, W. (Interatom, Bensberg, Germany)

Abstract

The HTR-MODUL is a system which incorporates the advantageous safety characteristics of the HTR reactor design. A comparison with the conventional HTR concept with regard to shut down, decay-heat removal and safety barrier systems shows that they become much less important if not totally unnecessary for the HTR-MODUL design, from the viewpoint of safety. This higher level of inherent safety is due mainly to the reduced reactor size and power density as well as a special geometric design. Externally generated load cases - the two main load cases to be considered in Germany, earthquake and aircraft impact - already constitute a significant proportion of the safety risk for conventional reactor designs. The system's integrity with regard to safety under any eventuality is totally assured so long as the geometry which ensures passive heat removal is maintained. A single failure in the outer confinement does not in itself constitute a safety risk. Only several further failures of a specific nature, involving the pressurized primary system, could cause safety related problems. The main aims of any design appertaining to earthquake or aircraft-impact loads must be therefore to maintain a geometry which allows passive cooling and ensures the integrity of the pressurized primary system. These aims are most effectively reached by a special reactor building design which attempts to isolate the reactor components from the externally generated loads. A design concept for the building will be analyzed. This design maintains a high degree of reactor component isolation, which protects the components from aircraft induced vibrations, while still retaining an overall stiffness high enough to negate magnification of the important low frequency seismic loads.

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key words: Gas Cooled Reactor, Nuclear Technology
Reference:
IAEA IWGGCR specialists' meeting on gas-cooled reactor seismic design problems and solutions. San Diego, CA (USA). 30 Aug - 1 Sep 1982
International Atomic Energy Agency, Vienna (Austria).
IWGGCR--6, pp:147-160