The International Atomic Energy Agency asserts that the regulation of the safety of civil nuclear power requires national regulatory agencies to be effectively independent. However, in the early years of national civil nuclear power programs national nuclear industries were dominated by iron triangles or subgovernments of powerful actors with an interest in promoting the industry. The creation of an independent safety regulator requires a radical restructuring of the national governance framework. Windows of opportunity or critical junctures for such reform occur only occasionally. This paper examines the cases of France, Japan, and India to identify the factors that determine the degree of success in attempts to break the power of nuclear iron triangles or subgovernments and create an effectively independent regulator. This analysis shows a serious nuclear accident can create the opportunity to dismantle an iron triangle. The extent and speed with which reforms can be implemented depend greatly on pre‐existing and prevailing conditions. Key determinants include the power structures and attitudes toward nuclear power in elite politics, the degree of engagement of civil society, and pressures from international organizations. Of these, the first, elite politics, appears to be the most important in these three cases.