Officials and proponents of the cleanup say difficulties are inevitable given the monumental scale of the problems. But a growing number of critics say the troubles are at least partly a result of fundamental flaws in the current cleanup, and they wondered whether Tuesday’s announcement might have been made with an eye to the International Olympic Committee, which will decide shortly on the site of the 2020 Summer Games.

The cleanup efforts to date, critics said, were grandiose but ultimately ill-conceived public works projects begun as a knee-jerk reaction by the government’s powerful central ministries to deflect public criticism and to protect the clubby and insular nuclear power industry from oversight by outsiders.

The biggest public criticism has involved the government’s decision to leave the cleanup in the hands of Tepco, which has seemed incapable of getting the plant fully under control. Each step Tepco has taken seems only to produce new problems. The recent leaking tank was one of hundreds that have been hastily built to hold the 430,000 tons of contaminated water at the plant, and the amount of that water increases at a rate of 400 tons per day. On Wednesday, nuclear regulators said radiation levels at other spots near the tanks had risen, suggesting the possibility of other, still undetected, leaks.

Critics complain that the government-run committee that has overseen Tepco’s cleanup is loaded with nuclear industry insiders and overseen by the trade minister, Toshimitsu Motegi, whose ministry is in charge of promoting nuclear power. They say Japan may be able to come up with better, more sustainable plans if it opens the process to outsiders like Japanese nonnuclear companies and foreigners.

As the government takes a more direct hand in the cleanup, Mr. Motegi has acknowledged that the old approach is working poorly, if at all. “The response to the contaminated water problem has been left to Tepco, and has ended up looking like a game of whack-a-mole,” he told reporters on Monday.

Mr. Motegi’s ministry will now take charge of the plant’s cleanup. This will include the plan to stop the influx of groundwater into the reactor buildings by sealing them off behind a mile-long subterranean wall of ground frozen by liquid coolant.

Some critics have dismissed the “ice wall” as a costly technology that would be vulnerable at the blackout-prone plant because it relies on electricity the way a freezer does, and even more so because it has never been tried on the vast scale that Japan is envisioning and was always considered a temporary measure, while at Fukushima it would have to endure possibly for decades.