About 22,000 Japanese troops, along with 110 from the U.S., searched by land, air and sea.

"A month after the earthquake and tsunami, many people are still missing," said Japanese defense ministry spokesman Norikazu Muratani. "We would like to do our utmost to find bodies for their families."

As many as 25,000 people are feared to have died in the March 11 disaster, but only 13,000 deaths have been confirmed. Many bodies have likely washed out to sea and will never be found.

A similar three-day search with even more troops a week ago found just 70 bodies, underscoring the difficulties of locating victims in the debris along the coast washed away by the tsunami.

The latest search was to last just one day and did not include the evacuation zone around the tsunami-flooded nuclear complex that is spewing radiation. Troops and police officers decked out in full protective gear continue the dangerous, painstaking work of searching the area closest to the Fukushima Dai-ichi plant.

Workers have spent the past month frantically trying to stop radiation spewing from the plant by restoring cooling systems, but they still have a long way to go. Radiation in water pooling around the complex has slowed efforts to stabilize the reactors, but workers made progress Saturday toward cleaning up that contamination.

In a move that prompted some criticism from neighboring countries, engineers decided earlier this month to deliberately pump less-contaminated water into the ocean from a storage facility they thought might make a good receptacle for the more highly radioactive water. They are also pumping out water from subdrains to keep it from backing up.

Work at the plant has been slow because radiation levels are so high in some areas that workers can enter only for short periods of time, or not at all.

On Saturday, two 190,000-pound (86,000-kilogram) concrete pumps that have been retrofitted to spray water and can be operated by remote control were on their way to the plant from Atlanta and Los Angeles.

The plant operator, Tokyo Electric Power Co., is also hoping to use T-Hawk drone aircraft made by Honeywell to inspect hard-to-access areas of the plant. The drone can be operated from six miles (10 kilometers) away and transmit video and still images.

Residents who live within 12 miles (20 kilometers) of the plant have been evacuated over radiation concerns. There has been some talk in recent days that officials might organize tours for people to visit their homes, but Trade Minister Banri Kaieda said Saturday that more planning was needed to ensure the safety of such trips.

"The residents had to rush out with barest necessities, and they are eager to go back as soon as possible to bring back things that they need," he said in Tokyo after a day trip to the complex. "But such tours must be brief, systematic and safe."

The contamination has raised concerns about food safety, and the government announced Friday that it was setting a new radiation standard for rice and would prohibit farmers from planting in soil with levels of radioactive cesium that are too high. Rice grown in soil not considered too contaminated will also be checked for radiation before it can be shipped.

Meanwhile, 250,000 households in northern Japan were still without running water and electricity Sunday. Some have not had it since the tsunami, while others lost it in a magnitude-7.1 aftershock Thursday that killed three people and rattled nerves but did not cause extensive damage.