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HEAT EXCHANGER TEMPERATURE RESPONSE FOR DUTY-CYCLE TRANSIENTS IN THE NGNP/HTE
Figure 2: Power conversion unit equipment configuration
Figure 3: High-temperature steam electrolysis equipment configuration
Duty-cycle transients
The duty-cycle event list defines the types and frequency of transients that form the plant design
basis. The temperature time history for these events is calculated to generate the corresponding
time-varying thermally-induced stresses. The damage plant components will sustain over a 40-year
lifetime is then estimated from this data. Given current target NGNP conditions the IHX appears to be
the component with the limiting lifetime. A main concern is transient-induced temporary imbalance
between energy production in the nuclear plant and energy absorption in the chemical plant and the
resulting time-varying temperatures that develop across the IHX.
An important consideration from the standpoint of analysis of the combined NGNP/HTE plant is
the types of transients in the duty cycle list. About 85% of the useful reactor thermal power (i.e. that
reactor power not ultimately rejected as waste heat) ends up being communicated to the chemical
plant as electrical power passed through the NGNP/HTE interface. Thus transients in the chemical
plant act on the reactor through changed electric power load and are therefore from the standpoint of
the nuclear plant classic electric-load transients. And transients in the nuclear plant are just the classic
transients for an electricity-only nuclear plant. Therefore the duty-cycle events for the NGNP/HTE that
cause thermal fatigue in the nuclear plant will be essentially the same set of transients considered in
electricity-only nuclear plants. These transients are described below.
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