Keywords: heat exchangers, helical–coil, NGNP, next generation nuclear plants, reactor design, steam generators, transient analysis, RELAP5, nuclear energy, nuclear power, high–temperature gas–cooled reactors, HTGR, pressure loss, feedwater flow, main steam valve closure, returning gas temperature, heat load step change
RELAP5–3D transient modelling for NGNP integrated plant
The High–Temperature Gas–cooled Reactor (HTGR) is designed with outlet temperatures ranging between 750°C and 800°C. These high outlet temperatures enhance the power production efficiency and facilitate a variety of industrial applications. The objective of this study is to understand the response of the primary system to potential transients in the secondary system. For this analysis, the transient condition originates in the Intermediate Heat Exchanger (IHX) or Steam Generator (SG) of the HTGR–integrated plant. The transients analysed are: a loss of pressure; loss of feedwater flow; inadvertent closure of main steam valve; decrease in returning gas temperature and heat load step change. The results show a large dependence on the negative reactivity added to the fuel as a function of increased temperature. The returning gas temperature decrease transient resulted in the highest fuel temperature (1361°C). Fuel temperature was shown to be less than the 1600°C fuel limit for each case analysed.