Design Options to Enhance the Safety of a 600MWe LFR

The SRES scenarios forecast a significant increase in nuclear power. In order to achieve better public acceptance of nuclear power it is at first necessary to reduce the radiotoxic inventory of the spent fuel from LWRs by burning the long-lived actinides. Furthermore, a much more efficient use of the fuel is needed to reduce the amount of mining, milling and enriching in order to prevent a strong upward pressure on uranium prices. Lead or lead alloy cooled fast reactors are promising regarding actinide burning and self-breeding. The latter allows to keep the burn-up swing low, which is safety-relevant because of no need for much inserted reactivity, and it would also facilitate remote siting due to a several year long irradiation cycle. Heavy metalcooled modular reactors have already been shown to have favorable behavior in severe accident simulations. In the EU, there is an interest in a 600 MWe lead-cooled reactor as part of the Generation IV effort. In this paper, an unprotected loss-of-flow calculation with no negative feedbacks taken into account is shown to lead to a benign behavior. The emergency decay heat removal with ex-vessel air-cooling is demonstrated for a more compact and a more pancake-like core. Furthermore, the MCNP-calculated Doppler, coolant temperature and cladding motion feedbacks are evaluated for both core configurations. Additionally, the change in reactivity during a few years burn-up is calculated for an initial load of spent LWR-UOX fuel. It is shown that the reactivity burn-up swing can be limited to 3dollars in 3 years.

WIDER Hartmut;  TUCEK Kamil;  FUETTERER Michael; 

CARLSSON Johan; 

2006-06-06

Korean Nuclear Society

JRC33621