- UCFR (Ultra-long-life Core Fast Reactor)
The concept for UCFR is designed to be operating at higher temperature and neutron dose than other liquid metal-cooled fast reactors and the refueling time is at least 30 years.
Because of longer refueling time, a large amount of fission gas is expected to be built up inside of the cladding. Therefore, internal pressure is increasing because of produced fission gas.
The fuel rod of UCFR must be designed to control the pressure generated by released fission gas. Thus several alternative concepts are being considered for UCFR design.
– Fission Gas Release
There are three means available to accommodate the fission gas:
- Allow additional volume within the fuel rod so that the allowable pressure is not exceeded.
- Remove the fission gas to a plenum external from the fuel rod:
It requires a means for transferring gas from the rod to the external plenum. If the external plenum was located apart from the fuel assembly, small tubes would be needed to connect the rods and the plenum. It would greatly clutter the interior of the pressure vessel.
- Vent the fission gas directly to the coolant
