A pressure-tube Advanced Burner Test Reactor concept

A new steady-state fast neutron test reactor has been conceptually designed. This paper presents a new concept for a CANDU-based fast test reactor that is horizontal in orientation, with individual pressure/Calandria tubes (PT/CT) running the entire length of the scattering-medium tank (Calandria) filled with Lead-Bismuth-Eutectic (LBE). This approach for a test reactor will provide more flexibility in refueling, sample removal, and ability to completely reconfigure the core to meet different users’ requirements. Full core neutronic analysis showed a small hexagonal reactor, LBE-cooled, trans-uranics (TRU)-67Zr fuel with HT-9 cladding and structures, with a core power of 100 MWth produced a fast flux (>0.1 MeV) of 1.4 × 1015 n/cm2 s averaged over the whole length of six irradiation channels with a total testing volume of more than 77 l. Loading of TRU from legacy UO2 spent fuel allowed core continuous operation for 180 effective full power days with a net fissile-Pu burning rate of ∼6.4%. Since high neutron fluence impact on PT/CT might be an issue of concern for this design, oxide dispersion strengthened (ODS) ferritic steel was used as PT/CT material without any impact on core neutronic behavior. An innovative shutdown/control system which consisted of the six outermost fuel channels was proven to be effective in shutting the core down when flooded with boric acid as a neutron absorber. The new shutdown/control system has the advantage of causing the minimum perturbation of the axial flux shape when the control channels are partially flooded with boric acid. A preliminary thermal-hydraulic analysis of LBE produced acceptable pumping power and clad temperature. Voiding the core from its LBE coolant resulted in a positive reactivity insertion which is typical of most fast reactors. Hypothetical accidents of draining the Calandria and/or the external LBE reflector tank of the LBE core resulted in negative reactivity insertion which shut the reactor down.