11. Most reactor designs use the naturally occurring mix of lithium isotopes. 12. The iodine pit effect has to be taken in account for reactor designs . 13. In principle, almost any reactor design could possibly be tweaked to become a breeder. 14. Nevertheless, newer reactor designs intended to provide increased safety have been developed over time. 15. As such, no true gas-cooled fast reactor design has ever been brought to criticality. 16. Nuclear proponents have tried to boost public support by offering newer, safer, reactor designs . 17. Fermi 1 was a liquid metal ( sodium ) cooled fast breeder reactor design . 18. Molten salt reactor designs carry out fluoride volatility reprocessing continuously or at frequent intervals. 19. In most stationary pebble-bed reactor designs , fuel replacement is continuous. 20. UCS has been critical of proposed Generation III reactor designs .
