TOKYO — The Tokyo Electric Power Company began dumping more than 11,000 tons of radioactive water from the Fukushima Daiichi nuclear plant into the Pacific Ocean on Monday, mostly to make room in storage containers for increasing amounts of far more contaminated runoff.

The water, most of it to be released over two days, contains about 100 times the legal limit of radiation, Tokyo Electric said. The more contaminated water has about 10,000 times the legal limit.

The effort would help workers clearing radioactive water from the turbine buildings at the damaged reactors, making it less dangerous to reach some of the most crucial controls for their cooling systems, which were knocked out by the 9.0-magnitude earthquake and tsunami that struck northeast Japan on March 11. The hopes are that the cooling systems can be revived and bring the plant back under control.

But the pumping effort is not expected to halt, or even alter, a gushing leak from a large crack in a six-foot-deep pit next to the seawater intake pipes near the No. 2 reactor. The leak, discovered Saturday, has been spewing an estimated seven tons of highly radioactive water an hour directly into the ocean; attempts to trace and plug it have so far failed.