HTGR Knowledge Base

Conference Article: Passive decay and residual heat removal in the MHTGR

Dilling, D.A.; Ghose, S.K.; Berkoe, J.M. (Bechtel National, Inc., San Francisco, CA (United States)); Caspersson, S.A. (ABB/Combustion Engineering, Inc., Windsor, CT (United States)); Bramblett, G.C. (General Atomics, San Diego, CA (United States))

Abstract

The modular high temperature gas-cooled reactor (MHTGR) being developed in the United States has the capability to reject decay and residual heat passively by conduction, natural convection, and radiation from the reactor core to the ultimate heat sink - the atmosphere - when normal heat rejection systems are unavailable. The method proposed for the U.S. MHTGR is referred to as the Reactor Cavity Cooling System (RCCS) and makes use of an uninsulated reactor vessel located in an enclosed cavity. The cavity walls are lined with cooling panels that allow outside air to flow in and out in an open once-through natural circulation loop. In this arrangement, the heat removal takes place first by transferring heat from the reactor core to the vessel by conduction, radiation and natural convection. Second, heat is transferred from the uninsulated vessel to the cooling panels primarily by radiation from the hot vessel surface to the relatively cold panel surface, and partly by natural convection of the enclosed cavity air. Third, heat is transported and rejected to the atmosphere by buoyancy-driven natural circulation of outside air through the cooling panels. The system functions at all times and does not rely on any active component or operator action. The operator cannot start, operate, or terminate the heat removal process.

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key words: Gas Cooled Reactor, Nuclear Technology
Reference:
Specialists meeting on decay heat removal and heat transfer under normal and accident conditions in gas cooled reactors. Juelich (Germany). 6-8 Jul 1992
International Atomic Energy Agency, Vienna (Austria)
IAEA-TECDOC--757, pp:75-82