The Tennessee Valley Authority was overcharged nearly $4.4 million by a contractor at the Watts Bar Nuclear Power Plant for construction of the Unit 2 reactor from 2013 to 2015, according to an audit released Wednesday.

TVA's inspector general said Williams Plant Services (WPS) used labor classifications not provided in its contract for nearly $3.5 million of work at Watts Bar and another $430,322 for excessive markups, ineligible overtime and other unsupported labor costs. The contractor also improperly billed for $435,624 of temporary living allowances and travel costs, according to TVA auditors.

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