 Weinberg was fired by the Nixon administration from ORNL in 1973 after 18 years as the laboratory 's director , because he continued to advocate increased nuclear safety and molten salt reactors ( MSRs ) , instead of the Administration 's chosen Liquid Metal Fast Breeder Reactor ( LMFBR ) that the AEC 's Director of Reactor Division , Milton Shaw , was appointed to develop . Weinberg 's firing effectively halted development of the MSR , as it was virtually unknown by other nuclear laboratories and specialists . There was a brief revival of MSR research at ORNL as part of the Carter administration 's nonproliferation interests , culminating in ORNL @-@ TM @-@ 7207 , " Conceptual Design Characteristics of a Denatured Molten @-@ Salt Reactor with Once @-@ Through Fueling " , by Engel , et al . , which is still considered by many to be the " reference design " for commercial molten salt reactors . 
