TOKYO -- Japan will begin restarting its idled nuclear plants after new safety guidelines are in place later this year, Prime Minister Shinzo Abe said Thursday, moving to ensure a stable energy supply despite public safety concerns after the Fukushima disaster.
In a speech to Parliament, Mr. Abe pledged to restart nuclear plants that pass the tougher guidelines, which are expected to be adopted by a new independent watchdog agency, the Nuclear Regulation Authority, as early as July. He did not specify when any of the reactors might resume operation, and news reports have suggested that it might take months or even years to make the expensive upgrades needed to meet the new safety standards.
Still, by making the promise in front of the Diet, Mr. Abe indicated in the strongest way yet that he planned to move ahead with a campaign pledge to reverse his predecessor's hopes that Japan would begin weaning itself off nuclear energy.
The speech came as the World Health Organization published a comprehensive, two-year analysis on the health risks associated with the 2011 disaster suggesting that the chance of getting certain types of cancers had increased slightly among children exposed to the highest doses of radioactivity. But the report said that there would most likely be no observable increase in cancer rates in the wider Japanese population.
The study's authors warned, however, that their assessment was based on limited scientific knowledge; much of the data on health effects from radiation is based on acute exposures like those that followed the bombings of Hiroshima and Nagasaki and not chronic, low-level exposure. Near the Fukushima plant, some densely populated areas are expected to remain contaminated with relatively low levels of radioactive materials for decades.
The government's initial reaction to the report -- saying it overestimated the risks by failing to fully take into account government evacuations of citizens -- suggested that officials did not see it as a help for Mr. Abe's plans. Antinuclear sentiments in Japan are now strong, and the results could feed fears of any increased risks.
The question of when, and whether, to restart the plants has dogged the country for two years, as politicians and ordinary Japanese try to balance their fears of a moribund economy when oil and gas costs have already hurt the balance of trade and worries over another environmental crisis, especially if the industry is not well regulated.
Lax regulation and a cozy relationship between the nuclear industry and the government helped make Japan vulnerable to the Fukushima accident, the world's second-worst nuclear plant disaster.
All of Japan's 50 operable nuclear reactors were shut down following the March 2011 triple meltdown, which spewed radiation across northern Japan after a huge earthquake and tsunami knocked out vital cooling systems. Two were later restarted as an emergency measure to avert power shortages in the heavily populated region that includes the cities of Osaka and Kyoto.
Leaders from the previous Democratic Party government had vowed to slowly phase out nuclear power by the 2030s in favor of cleaner alternatives like solar and wind power. But Mr. Abe, who took power after his Liberal Democratic Party won national elections in December on a platform of economic revitalization, said the phaseout would keep Japan from the cheap electricity it needs to compete economically.
On Thursday, Mr. Abe said that Japan had learned the need for tougher safety standards, and he said the new standards would be enforced "without compromise."
Mr. Abe also said Japan would continue seeking energy alternatives to reduce its dependence on nuclear power.
In January, the new nuclear agency released a list of its proposed safety regulations, which include higher walls to protect against tsunamis, additional backup power sources for the cooling systems and construction of specially hardened earthquake-proof command centers. The rules surprised many for their toughness, though skeptics worry that industry supporters in the government will manage to get around the regulations.
According to a report by the newspaper Asahi Shimbun, none of Japan's 16 undamaged commercial nuclear plants would pass the new standards. The agency has said the new guidelines will be finalized and put in place by July 18.
The W.H.O. study focused on cancer incidence, not deaths, and some of the cancers listed are serious but have good rates of survival.
According to the study, girls exposed as infants to radioactivity in the most contaminated regions of Fukushima Prefecture faced a 70 percent higher risk of developing thyroid cancer than would be expected normally. The report pointed out, however, that the normal risk of thyroid cancer was just 0.75 percent, and that the additional lifetime risk would raise that to 1.25 percent.
Girls exposed to radioactivity as infants in the most heavily contaminated areas also had a 6 percent higher risk of developing breast cancer, and a 4 percent higher risk of developing cancers that cause tumors. Meanwhile, boys exposed as infants had a 7 percent higher chance of developing leukemia.
The study also said that about a third of the emergency workers who remained to try to stabilize the Fukushima Daiichi plant were estimated to have a slightly increased risk of developing leukemia, thyroid cancer and other types of cancer.
The analysis was based on data available as of September 2011, and takes into account airborne contamination as well as contaminated food, water and other sources of contamination, the WH.O. said.
Some local government officials in Fukushima criticized the report for identifying specific areas and their associated exposure estimates. Radiation exposure is a sensitive topic in Japan, where victims of the Hiroshima and Nagasaki bombings often experienced discrimination in marriage, for example, because of feared health effects.
"I feel extreme anger over this excessive analysis, which will plunge more residents into fear," Mayor Norio Kanno of Iitate Village, told N.H.K. Iitate was one of the areas identified in the W.H.O. report as heavily contaminated. Villagers there are among tens of thousands of evacuees who have not been able to return home.
Matthew L. Wald contributed reporting from Washington.world
This article originally appeared in The New York Times.