Image: Inside Fukushima Nuclear Plant Evacuation Zone
Air Rabbit  /  Getty Images Contributor
The troubled Fukushima Daiichi Nuclear Power Plant is seen  south from the plant in Okuma, Fukushima, Japan. Japanese
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updated 4/16/2011 11:07:37 AM ET 2011-04-16T15:07:37

Levels of radioactivity have risen sharply in seawater near a tsunami-crippled nuclear plant in northern Japan, signaling the possibility of new leaks at the facility, the government said Saturday.

The announcement came after a magnitude-5.9 earthquake jolted Japan on Saturday morning, hours after the country's nuclear safety agency ordered plant operators to beef up their quake preparedness systems to prevent a recurrence of the nuclear crisis.

There were no reports of damage from the earthquake, and there was no risk of a tsunami similar to the one that struck the Fukushima Dai-ichi plant March 11 after a magnitude-9.0 earthquake, causing Japan's worst-ever nuclear plant disaster.

Since the tsunami knocked out the plant's cooling systems, workers have been spraying massive amounts of water on the overheated reactors. Some of that water, contaminated with radiation, leaked into the Pacific. Plant officials said they plugged that leak on April 5 and radiation levels in the sea dropped.

But the government said Saturday that radioactivity in the seawater has risen again in recent days. The level of radioactive iodine-131 spiked to 6,500 times the legal limit, according to samples taken Friday, up from 1,100 times the limit in samples taken the day before. Levels of cesium-134 and cesium-137 rose nearly fourfold. The increased levels are still far below those recorded earlier this month before the initial leak was plugged.

The new rise in radioactivity could have been caused by the installation Friday of steel panels intended to contain radiation that may have temporarily stirred up stagnant waste in the area, Hidehiko Nishiyama of the Nuclear and Industrial Safety Agency told reporters. However, the increase in iodine-131, which has a relatively short eight-day half life, could signal the possibility of a new leak, he said.

"We want to determine the origin and contain the leak, but I must admit that tracking it down is difficult," he said.

Video: Contaminated corpses removed in Japan (on this page)

Authorities have insisted the radioactivity will dissipate and poses no immediate threat to sea creatures or people who might eat them. Most experts agree.

Regardless, plant workers on Saturday began dumping sandbags filled with zeolite, a mineral that absorbs radioactive cesium, into the sea to combat the radiation leaks.

Meanwhile, the newspaper Asahi Shimbun reported, without citing its sources, that a secret plan to dismantle Tokyo Electric Power Co., which runs the radiation-leaking Fukushima plant, was circulating within the government. The proposal calls for putting TEPCO, the world's largest private electricity company, under close government supervision before putting it into bankruptcy and thoroughly restructuring its assets. Most government offices were closed Saturday, and the report could not be immediately confirmed.

In the wake of the nuclear crisis, the government ordered 13 nuclear plant operators to check and improve outside power links to avoid earthquake-related outages that could cause safety systems to fail as they did at the Fukushima plant, Nishiyama told reporters late Friday. The operators, including TEPCO, are to report back by May 16.

Power outages during a strong aftershock on April 7 drove home the need to ensure that plants are able to continue to operate crucial cooling systems and other equipment despite earthquakes, tsunamis and other disasters, Nishiyama said.

Utility companies were ordered to reinforce the quake resistance of power lines connected to each reactor or to rebuild them. They also must store all electrical equipment in watertight structures. Earlier, the nuclear agency ordered plant operators to store at least two emergency backup generators per reactor and to install fire pumps and power supply vehicles as further precautions.

The massive 46-foot (14-meter) wave that swamped Fukushima Dai-ichi last month knocked out emergency generators meant to power cooling systems. Since then, explosions, fires and other malfunctions have compounded efforts by TEPCO to repair the plant and stem radiation leaks.

TEPCO said Saturday it had moved power sources for some of the reactors at the stricken plant to higher ground by Friday evening in order to avoid another disastrous failure in the event of a tsunami.

'Far from the end'
Goshi Hosono, an adviser to the prime minister and member of the nuclear crisis management task force, said the damaged reactors were much more stable than they had been earlier in the crisis and TEPCO was preparing to unveil a plan for restoring cooling capacity to the ailing reactors "soon."

"Problems are still piled up and we are far from the end of crisis," he told a TV news program, citing radioactive water as one of the biggest headaches. "I expect there will be more mountains that we have to climb over."

The crisis at the Fukushima plant has forced tens of thousands of people to evacuate the area, while radiation leaks have contaminated crops and left fishermen unable to sell their catches, adding to the suffering of communities already devastated by earthquake and tsunami damage.

Government officials fanned out across the affected areas to explain their decisions and calm nerves.

Deputy Chief Cabinet Secretary Tetsuro Fukuyama apologized for the uncertainty and confusion to residents in Iitate village, parts of which the government recommended be evacuated because of the nuclear crisis.

"Everyone in the village must be extremely troubled, uncertain and worried," he said, promising to provide temporary housing and financial support for the residents, many of them farmers.

In the city of Inawashiro, Hiroshima University Professor Kenji Kamiya, who has been appointed a health risk adviser to Fukushima prefecture, met with about 250 education officials to explain that radiation levels in the area do not pose an immediate or significant threat to the public.

"I hope people understand that the levels we are seeing are fairly low. Even in the most impacted areas, we have screened more than 1,000 children for radiation abnormalities in their thyroids and have found none at all," he said.

Kamiya has been giving almost daily lectures in an effort to prevent people from overreacting to the possible danger.

"People fear things that they don't understand. We were even afraid before of the rain, because we just didn't know if it was safe," said Takaaki Kobayashi, a father of two grade school children. "I feel more comfortable now about sending kids to school. It helps to understand."

___

Associated Press writers Eric Talmadge in Inawashiro and Elaine Kurtenbach and Noriko Kitano in Tokyo contributed to this report.

Copyright 2011 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

Video: Contaminated corpses removed in Japan

Photos: Triple tragedy for Japan

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  1. Office workers in Tokyo look at smoke rising over the skyline after the magnitude 9.0 earthquake off Japan's northeast coast on March 11, 2011. (Xinhua via Getty Images) Back to slideshow navigation
  2. Waves pour over a seawall and roar into a seaside village near the mouth of Hei River on March 11 as the tsunami generated by the massive earthquake hits shore. (Mainichi Newspaper via EPA) Back to slideshow navigation
  3. Hotel employees squat around a pillar at the hotel's entrance in Tokyo after the powerful earthquake on March 11. (Itsuo Inouye / AP) Back to slideshow navigation
  4. A tsunami wave sweeps away homes in its path in Natori, Miyagi prefecture, on March 11. (Kyodo News via AP) Back to slideshow navigation
  5. One house bursts into flames after the tsunami swept it and many of its neighbors off their foundations in Natori on March 11. (Kyodo News via Reuters) Back to slideshow navigation
  6. Shaken evacuees gather in Shinjuku Central Park in Tokyo on March 11. (Kyodo News via Reuters) Back to slideshow navigation
  7. An aerial photo shows Sendai Airport being inundated by a tsunami on March 11. Later reports said the first wave hit 26 minutes after the quake struck at 2:46 p.m. local time. (Kyodo News via Reuters) Back to slideshow navigation
  8. A swirling pattern is evident in this aerial photo of the tsunami as it hit a port in Oarai, Ibaraki prefecture on March 11. (Kyodo News via AP) Back to slideshow navigation
  9. Toya Chiba, a reporter for local newspaper Iwate Tokai Shimbun, is swept away while taking pictures at the mouth of the Owatari River during the tsunami at Kamaishi port, Iwate prefecture. Chiba managed to survive in the rush of water by grabbing a dangling rope and climbing onto a coal heap around 30 feet high after being swept away for about 100 feet, Kyodo News reports. (Kamaishi Port Office / Kyodo via Reuters) Back to slideshow navigation
  10. Natural gas containers burn in Chiba Prefecture near Tokyo, on March 11. The massive earthquake triggered many fires, posing additional problems for first responders. (Kyodo News via Reuters) Back to slideshow navigation
  11. Containers for cargo are strewn about like giant Legos in Sendai, Miyagi prefecture, on March 12. (Itsuo Inouye / AP) Back to slideshow navigation
  12. People use a floating container to ferry survivors to higher ground in Kesennuma City, Miyagi prefecture, on March 12. (Kyodo News via Reuters) Back to slideshow navigation
  13. Cars swept into a jumble by the tsunami are seen in Hitachi City, Ibaraki prefecture, on March 12. (Yomiuri via Reuters) Back to slideshow navigation
  14. A line of residents seeking water snakes across the playground of a school in Sendai, Miyagi prefecture, on March 13, two days after the earthquake. (Kyodo News via AP) Back to slideshow navigation
  15. Japanese firefighters rescue tsunami survivors in Natori, Miyagi prefecture, on March 13. (EPA) Back to slideshow navigation
  16. A Japanese home drifts in the Pacific Ocean off the coast of Sendai in this photograph taken on March 13. (Dylan McCord / U.S. Navy via Reuters) Back to slideshow navigation
  17. A woman cries while sitting on a road in the devastated city of Natori, Miyagi prefecture, on March 13. (Asahi Shimbun / Reuters) Back to slideshow navigation
  18. An "SOS" signal scrawled on the sports field of a high school beckons potential rescuers on March 13 in the town of Minami Sanriku, Miyagi prefecture. (Kyodo News via Reuters) Back to slideshow navigation
  19. Editor's note:
    This image contains graphic content that some viewers may find disturbing.

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    The body of a victim of the twin disaster lays on the stairs of a destroyed house in Sendai, Miyagi prefecture, on March 13. (David Guttenfelder / AP) Back to slideshow navigation
  20. Sixty-year-old Hiromitsu Shinkawa waves to members of Japan Maritime Self-Defence Force preparing to rescue him about 9 miles off Fukushima prefecture on March 13. Shinkawa survived by clinging to a piece of roof after the tsunami hit his hometown of Minamisoma. (Japanese Defense Forces via AFP - Getty Images) Back to slideshow navigation
  21. People walk along a flooded street in Ishimaki City, Miyagi prefecture on March 13. (Kyodo News via Reuters) Back to slideshow navigation
  22. An explosion at the Fukushima Dai-ichi nuclear power plant sends a plume of smoke skyward on March 14. The blast was believed to have been caused by a buildup of hydrogen inside the reactor building, caused by the partial meltdown of nuclear fuel inside. The plant was crippled after the earthquake cut power to the station and tsunami waves knocked out backup generators. (NTV / FCT) Back to slideshow navigation
  23. A 1-year-old boy is re-checked for radiation exposure after being decontaminated in Nihonmatsu, Fukushiima prefecture, on March 14. (Toru Nakata / Asahi Shimbun via AP) Back to slideshow navigation
  24. Officers examine a Mitsubishi F-2 fighter jet of the Japanese Air Self-Defense Force on March 14. The warplane was swept by the tsunami into a building at Matsushima base in Higashimatsushima, Iwate prefecture. (Kyodo News via Reuters) Back to slideshow navigation
  25. Japanese rescue team members carry the body of a man out of the village of Saito on March 14. (David Guttenfelder / AP) Back to slideshow navigation
  26. A woman survivor is reunited with her relatives at a shelter in Rikuzentakata in Iwate prefecture, on March 15. (Lee Jae-Won / Reuters) Back to slideshow navigation
  27. A bicyclist wheels across a hellish landscape in what was the city of Minami Sanriku, Miyagi prefecture, on March 15. (David Guttenfelder / AP) Back to slideshow navigation
  28. Tsunami survivors cook on an open fire in front of their damaged house in Ishinomaki, Miyagi Prefecture, on March 15. (Kyodo News via AP) Back to slideshow navigation
  29. Vehicle headlamps illuminate a devastated section of Yamada town, Iwate prefecture, on March 16. (Jiji Press via AFP - Getty Images) Back to slideshow navigation
  30. Evacuees carry bowls of pork soup from a soup kitchen to a makeshift shelter in Minami Sanriku, Miyagi prefecture, on March 16. (Tsuyoshi Matsumoto / The Yomiuri Shimbun via AP) Back to slideshow navigation
  31. Refugees, including 53 people who were rescued from a retirement home during the tsunami, take shelter inside a school gym in the leveled city of Kesennuma, Miyagi prefecture, on March 17. (David Guttenfelder / AP) Back to slideshow navigation
  32. Members of Japan Self-Defense Force pray over the body of a tsunami victim in Onagawa, Miyagi prefecture, on March 20. (Shuji Kajiyama / AP) Back to slideshow navigation
  33. Tomoko Yagi looks at two firetrucks that were tossed around like toys in the tsunami in Kamaishi, Iwate prefecture, on March 20. (Lee Jae-Won / Reuters) Back to slideshow navigation
  34. Survivors relay boxes of relief supplies arriving at their evacuation center in Ishinomaki, Miyagi prefecture, on March 21. (Kunihiko Miura / The Yomiuri Shimbun via AP) Back to slideshow navigation
  35. A boat juts out from the top of a building in Otsuchi, Iwate prefecture, on March 22. (Hiroto Nomoto / The Yomiuri Shimbun via AP) Back to slideshow navigation
  36. Manami Kon, 4, uses the Japanese "hiragana" characters she just learned to write a letter to her missing mother in the devastated city of Miyako, Iwate prefecture, on March 22 . "Dear Mommy. I hope you're alive. Are you OK?" read the letter, which took about an hour to write. Also missing were the little girl's father and sister. (Norikazu Tateishi / The Yomiuri Shimbun via AP) Back to slideshow navigation
  37. Tokyo Electric Power Co. workers collect data in the control room for the Unit 1 and 2 reactors at the crippled Fukushima Dai-ichi nuclear power plant on March 23. (Nuclear and Industrial Safety Agency via AP) Back to slideshow navigation
  38. An aerial photo taken by an unmanned drone shows the damaged units of the Fukushima Dai-ichi nuclear plant on March 24. (Air Photo Service via EPA) Back to slideshow navigation
  39. Two residents exchange words as they are reunited two weeks after the earthquake and tsunami in a makeshift public bath set up outside a shelter in Yamamoto, Miyagi prefecture, on March 25. (Shuji Kajiyama / AP) Back to slideshow navigation
  40. A Japanese funeral parlor worker shovels dirt onto the coffins of victims of the earthquake and tsunami at a mass funeral in Yamamoto, Miyagi prefecture, on March 26. (David Guttenfelder / AP) Back to slideshow navigation
  41. A lone pine tree stands in a devastated area iof Rikuzentakaka, Iwate prefecture, on March 27. It was the only one among tens of thousands of other pine trees forming "Takata Matsubara," or Takata seaside pine forest, standing after the March 11 tsunami washed away all the others, local media said. (Kyodo News via AP) Back to slideshow navigation
  42. A woman whose house was washed away loses control of her emotions on March 29 as she talks about the disaster that befell her hometown of Kesennuma, Miyagi prefecture. (Kuni Takahashi) Back to slideshow navigation
  43. Japanese Emperor Akihito and Empress Michiko, left, talk with evacuees at Tokyo Budoh-kan evacuation center on March 30. (Issei Kato / Pool via AFP - Getty Images) Back to slideshow navigation
  44. Officials of the Tokyo Electric Power Co., (TEPCO), including Chairman Tsunehisa Katsumata, center, Vice President Takashi Fujimoto, second from left, bow before a news conference at the company's head office in Tokyo on March 30. (Itsuo Inouye / AP) Back to slideshow navigation
  45. A man rides a bicycle in between the ships that were washed ashore by the March 11 tsunami, on March 30, in Kesennuma, Miyagi prefecture. (Eugene Hoshiko / AP) Back to slideshow navigation
  46. An elderly woman waves to her grandchildren in Minamisanriku, Miyagi prefecture, on April 3, as authorities began a mass evacuation of approximately 1,100 homeless survivors to shelters elsewhere. (Jiji Press via AFP - Getty Images) Back to slideshow navigation
  1. Editor's note:
    This image contains graphic content that some viewers may find disturbing.

    Click to view the image, or use the buttons above to navigate away.

  2. Editor's note:
    This image contains graphic content that some viewers may find disturbing.

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  3. Editor's note:
    This image contains graphic content that some viewers may find disturbing.

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  4. Editor's note:
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Timeline: Crisis in Japan

How events have unfolded since a 9.0 earthquake struck northeast Japan, triggering a deadly tsunami and nuclear power disaster.

  1. Image: The wave from a tsunami crashes over a street in Miyako City, Iwate Prefecture in northeastern Japan
    Ho / Reuters
    Above: Timeline Crisis in Japan
  2. Interactive Japan before and after the disaster

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