A year after the 2011 Tōhoku earthquake and tsunami and subsequent Fukushima Daiichi nuclear disaster , the Nuclear Regulatory Commission ( NRC ) issued 9 orders to improve safety at domestic plants . Two applied to Watts Bar Unit 2 and required design modifications : " Mitigation Strategies Order " and " Spent Fuel Pool Instrumentation Order " . In February 2012 , TVA said the design modifications to Watts Bar 2 were partially responsible for the project running over budget and behind schedule . The second unit cost a total of $ 4.7 billion bringing the total cost of the plant to more than $ 12 billion
2011 Tōhoku earthquake and tsunami
2011 Tōhoku earthquake and tsunami
Watts Bar Nuclear Plant