HTGR Knowledge Base

Conference Article: Dynamics of a Small Direct Cycle Pebble Bed HTR

Abstract

The Dutch market for combined generation of heat and power indentifies a unit size of 40 MW thermal for the conceptual design of a nuclear congeneration plant. The ACACIA system provides 14 Mwe electricity combined with 17t/h of high temperature steam (220^oC, 10 bar) with a pebble bed high temperature reactor directly coupled with a helium compressor and a helium turbine.
To come to quantitative statements abjout the ACACIA transient behaviour, a calculational coupling between the high temperature reactor core analysis code package Panthermic (Panther-Termic/Direkt) and the thermal hydraulical code RELAP5 for the energy conversion system has been made.
It appears that the maximum fuel temperatures are naot reached during a LOFI or LOCI with a halted mass flow rate, but for situations with a small mass flow rate, 1-0.5 percent. As such, a LOFI or LOCI does not represent the worst-case scenatio in terms of maximal fuel temperature.

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Reference:

IAEA Technical Committee Meeting on “Gas Turbine Power Conversion Systems for Modular HTGRs”, held from 14-16 November 2000 in Palo Alto, California

International Atomic Energy Agency, Vienna (Austria). Technical Working Group on Gas-Cooled Reactors

IAEA-TECDOC--1238, pp:78-86