Radiation levels in pooled water tested in the No. 2 nuclear reactor’s turbine building at the Fukushima Daiichi power plant are 10 million times normal, utility company and government officials said Sunday.

Hidehiko Nishiyama, an official with Japan’s nuclear and industrial safety agency, said the surface water showed 1,000 millisieverts of radiation. By comparison, an individual in a developed country is naturally exposed to 3 millisieverts per year, though Japan’s health ministry has set a 250 millisievert per year cumulative limit before workers must leave the plant.

The 10-million-times normal reading applies to radioactive iodine-134 found in the No. 2 building’s pooled water, according to the nuclear safety agency. This isotope loses half its radioactive atoms every 53 minutes, compared to a half-life of every eight days for radioactive iodine-131 that has also been detected in recent days.

Two people working in and around the No. 2 reactor when the test result became known, according to an official with the Tokyo Electric Power Company, which runs the plant. Those individuals subsequently left, and work there has stopped until the government signs off on the power company’s plan to address the issue.

Work has similar ceased at the No. 3 reactor, where tests earlier indicated radiation 10,000 times normal in its own turbine building.

On Sunday, water was being pumped out of the No. 1 reactor’s turbine building — a process that authorities eventually want to repeat in the other two reactors’ buildings with pooled, and contaminated, water.

Authorities are still trying to pinpoint the relationship, if any, between these alarming readings from inside these buildings to a continued spike in radiation detected in seawater just offshore.

A Japanese nuclear safety official said Sunday that levels of radiation were 1,850 times normal at a monitoring post situated 330 meters (361 yards) into the Pacific Ocean. This is near the discharge canal for the Nos. 1, 2, 3 and 4 reactors.

On Saturday, similar readings from the same monitoring posts showed readings were 1,250 times above normal. The previous day, they’d been lower — at 104 times more than a typical level.

This substance is a biproduct during the nuclear energy process, and officials suspect the seawater contamination may be a direct result of problems at the plant.

Up until Sunday, the potential for contamination from the No. 3 reactor had been a primary concern. This unit, which has had a building severely damaged by a hydrogen explosion and that an official said last week might have leaked radiation from its reactor core, is the only one of the facility’s six reactors to use a combination of uranium and plutonium fuel, called MOX. Experts say this mix is considered more dangerous than the pure uranium fuel used in other reactors.

Three men laying cable in the No. 3 unit turbine building’s basement have been hospitalized after stepping in the highly radioactive water there on Thursday.

READ MORE: CNN