The core pressure drop characteristics in a CANDU 6 reactor

Highlights: ► The general characteristics for core pressure drop of CANDU 6 NPPs are deduced. ► The relationship between the inlet header temperature and core pressure drop has been secured. ► The magnetite transport mechanism in a CANDU 6 has been utilized. - Abstract: The core pressure drop characteristics in a CANDU 6 have been examined to reveal the mechanism inducing the difference in the core pressure drop among four passages. The general characteristics for the inlet header temperature and core pressure drop are deduced from the measured data of CANDU 6 NPPs. The passages, which are connected to the purification system, are shown to have a larger core pressure drop and lower inlet header temperature compared with other passages in a loop. The temperature difference among four inlet headers has been analytically obtained by considering the effect of the purification system and verified by the measured data of CANDU 6 NPPs. The relationship between the inlet header temperature and core pressure drop has been secured from the magnetite transport mechanism in a CANDU 6. The analytical computations for a CANDU 6 NPP have revealed that the core pressure drop difference among four passages is largely dependent on the single phase friction factor rather than the mass flow rate in a passage. The calculated single phase friction factors are in accord with the magnetite deposition characteristics derived from the difference in the inlet header temperature