Pressure rising in Japanese nuclear reactor

Tokyo (CNN) — Even as workers began to see some success in their battle to cool down reactors at the Fukushima Daiichi nuclear plant, Japanese officials said Sunday that they would have to release some radioactive gas into the air.

The country’s nuclear safety agency said releasing the gas was a necessary step to reduce mounting pressure in reactor No. 3’s containment vessel — the steel and concrete shell that insulates radioactive material inside.

“In order to be safe, we need to take measures to lower the pressure of the containment vessel. Now that means that air containing radioactive substances will be emitted into the atmosphere,” said Hidehiko Nishiyama of Japan’s Nuclear and Industrial Safety Agency.

Workers have let out radioactive steam to release pressure inside affected reactors in previous operations.

The No. 3 reactor is one of six at the nuclear plant, where workers have been struggling to stave off a full meltdown since a 9.0-magnitude earthquake and ensuing tsunami knocked out cooling systems.

The dual disasters, which struck March 11, devastated much of northeastern Japan. On Sunday, the country’s national police said 8,133 were confirmed dead and 12,272 remained missing as search efforts continued.

Authorities have evacuated about 200,000 people from a 20-kilometer (12.4-mile) area surrounding the plant, but the crisis there has sparked concern across the country as fears of a possible massive radiation release grow.

The situation has already impacted areas across Japan.

Very small amounts — far below the level of concern — of radioactive iodine have been detected in tap water in Tokyo and most prefectures near the Fukushima Daiichi plant damaged by last week’s monster earthquake and tsunami.

And on Saturday, the Japanese government said it was considering halting the sale of food from farms near the Fukushima plant after abnormally high levels of radiation were found in milk and spinach.

Tainted milk was found 30 kilometers (18 1/2 miles) from the plant, and spinach was collected as far as 100 kilometers (65 miles) to the south, almost halfway to Tokyo.

A person who consumed the tainted food continuously for a year would take in the same amount of radiation as a single CT scan, Chief Cabinet Secretary Yukio Edano said. That’s about 7 millisieverts or double what an average person in an industrialized country is exposed to in a year, according to the U.S. Food and Drug Administration.

At the plant itself, workers from the power company and firefighters helping douse reactors with massive streams of water are taking on the risk of far greater radiation exposure.

Firefighter Yasuao Sato told reporters his family was well aware of the risk — and proud that he was taking it.

When he sent a text message to his wife telling her he was heading to the troubled nuclear plant, he said her reply was simple: “Please become a savior for Japan.”

Six members of an emergency crew working to restore electricity at the plant have been exposed to more than 100 millisieverts of radiation per hour, the equivalent of getting 10 chest X-rays in that time period, Tokyo Electric Power Co. said.

Officials say regaining electrical power could bring cooling systems back online — a key step in curbing the further emission of radioactive material and preventing a full nuclear meltdown. A meltdown occurs when nuclear fuel rods get so hot that they melt the steel and concrete structure containing them, spilling out into the air and water with potentially deadly results.

Japan’s nuclear agency said workers will spend about five hours installing electrical cables Sunday before water spraying operations resume.

On Saturday, authorities set up a new system to spray seawater continuously on the troubled reactors for extended periods of time. Previously, firefighters, soldiers and electric company workers had manually done the same in brief intervals to avoid prolonged radiation exposure.

On Saturday, water was directed at the No. 3 reactor’s spent fuel pool in order to cool it and prevent the emission of more radioactive material into the atmosphere. Authorities have also started spraying the No. 4 reactor and planned to continue efforts there Sunday.