Nuclear Production of Hydrogen, Fourth Information Exchange ...

HEAT EXCHANGER TEMPERATURE RESPONSE FOR DUTY-CYCLE TRANSIENTS IN THE NGNP/HTE
Unprotected event
The upset begins with a loss of generator electric load. The control system is assumed to reduce the
pre-cooler and intercooler powers by reducing cold side flow rate. The objective is to bring the long-term
heat removal rate into balance with the reactor power which should be decreased to move the plant
toward a shutdown state. Failure to reduce the power of the coolers will overcool the plant and cause
the reactor inlet temperature to drop. This will add reactivity through a negative inlet temperature
coefficient and work against bringing the core power down. The inherent neutronic/decay heat power
response resulting from fuel and graphite reactivity temperature feedback is shown in Figures 23 and 24.
Figure 18: Protected loss of generator load – shaft speeds, short term
Figure 19: Protected loss of generator load – shaft speeds, long term
Figure 20: Protected loss of generator load – mass flow rates, short term
428 NUCLEAR PRODUCTION OF HYDROGEN – © OECD/NEA 2010