The Nuclear Regulation Authority began a regular safety inspection Monday of the troubled Monju prototype fast-breeder reactor after its operator was found to have carried out sloppy equipment checks.

The NRA will mainly seek to verify during the quarterly inspection through March 22 if the Japan Atomic Energy Agency has taken measures to correct its failure to check a raft of equipment last year, officials said.

The authority will also investigate whether the operator of the plant in Tsuruga, Fukui Prefecture, has been appropriately managing its fuel replacement unit inside the reactor that was repaired last August following an accident in 2010.