Moniz was meeting with top Japanese officials during his visit, including industry minister Toshimitsu Motegi, who is overseeing the government's role in the plant cleanup.
"Our decommissioning and decontamination industries stand ready to aid should Japan need their help," Moniz said. "The U.S. is ready to assist our partners with this daunting task."
He is due to visit the Fukushima plant on Friday.
Removing the fuel rods from the Unit 4 cooling pool is the first major step in a decommissioning process that is expected to last decades at the Fukushima Dai-ichi plant.
Japan's nuclear regulatory chairman Shunichi Tanaka has warned that removing the fuel rods is a painstaking, high risk process. He says he is more worried about that than the massive amounts of radiation-contaminated water that TEPCO is struggling to manage.
Despite the worries over potential risks from radiation escaping from the plant, Japan's ruling Liberal Democratic Party has pushed for a restart of nuclear reactors that have all been offline for safety checks and must be inspected under new guidelines.
Moniz said he expects nuclear power to remain a crucial part of the energy mix as the world moves away from fossil fuels in its effort to mitigate global warming. The Department of Energy has provided billions of dollars in loan guarantees for new nuclear plants in the U.S.
Smaller nuclear plants now under development probably offer the safest, most financially viable options, he said.
"We cannot lose perspective on nuclear as a clean, reliable supplier of baseload (electricity), while recognizing each country will make its own decisions," he said.
Japan has looked to the U.S., with its abundance of shale gas, as a supplier of more affordable natural gas to help meet energy shortfalls due to the closures of its nuclear plants.
The U.S. has restricted exports of such gas for the sake of energy security, though it recently approved plans for a liquefied natural gas terminal that is expected to process LNG for shipment to Japan.
Moniz cautioned that such supplies will still take some time, given the need for further regulatory approvals.
"We are working as fast as we can but hopefully LNG will flow to Japan within the next few years," he said.
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