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Conference Article: Aspects of water and air ingress accidents in HTRs

Wolters, J. (Kernforschungsanlage Juelich G.m.b.H. (Germany, F.R.). Inst. fuer Nukleare Sicherheitsforschung)

Abstract

The work has contributed towards improving the understanding of the processes taking place during water and air ingress accidents. The favourable design features of the THTR limit the pressure build-up in the primary circuit to values below critical values in water ingress accidents even when the source of water is not identified and shut-off. A pressure reduction by safety valves is in this case not necessary so that the accident consequences remain confined in the primary circuit. The expected air ingress rates following a depressurization accident through an opening in the top head of the PCRV are extremely small in the case of complete integration of the primary circuit in the PCRV. The chemical processes in the primary circuit remain so limited that no danger for the fuel elements and the containment exists. The often feared ''graphite fire'' can be excluded even in the case when the circulators of the after-heat removal systems take in a high percentage of containment atmosphere. The core is cooled down safely.

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key words: air; computer codes; eccs; fission product release; fuel element failure; graphite; htgr type reactors; leaks; primary coolant circuits; reactor safety; steam generators; water
Reference:
International Atomic Energy Agency, Vienna (Austria). International Working Group on Gas-Cooled Reactors. Specialists meeting on gas-cooled reactor safety and licensing aspects, Lausanne, Switzerland, 1-3 September 1980. Summary report. Jan 1981
International Atomic Energy Agency, Vienna (Austria). International Working Group on High-Temperature Reactors.
IWGGCR--1, pp:124-131