The Washington Post: Chico Harlan and Brian Vastag, Sunday, March 27, 

TOKYO — Already-grave conditions at the Fukushima Daiichi nuclear plant worsened Sunday with the highest radiation readings yet, compounding both the risks and challenges for workers trying to repair the facility’s cooling system.

Leaked water sampled from one unit Sunday was 100,000 times more radioactive than normal background levels — though the Tokyo Electric Power Co., which operates the plant, first calculated an even higher, erroneous, figure that it didn’t correct for several hours.

Tepco apologized Sunday night when it realized the mistake; it had initially reported radiation levels in the leaked water from the unit 2 reactor as being 10 million times higher than normal, which prompted an evacuation of the building.

After the levels were correctly measured, airborne radioactivity in the unit 2 turbine building still remained so high — 1,000 millisieverts per hour — that a worker there would reach his yearly occupational exposure limit in 15 minutes. A dose of 4,000 to 5,000 millisieverts absorbed fairly rapidly will eventually kill about half of those exposed.

(Full story in links below)

UPDATE AS OF 9:30 A.M. EDT, MARCH 26, 2011

Japanese scientists yesterday detected higher levels of radioactive iodine in seawater at water outlets near the Fukushima Daiichi nuclear power plant.

"Iodine 131 was detected at a level 1,250 times the national safety limit," Hidehiko Nishiyama of the Nuclear and Industrial Safety Agency said during a news conference. Officials said there is no immediate danger to residents near the plant from these levels.

Samples taken on Friday were significantly higher than those taken on Wednesday, which had 147 times the legal concentration of I-131. Authorities said the concentration of radioactive materials in the water will decrease as the water is diluted by ocean currents. Indeed, a sample taken at 8:50 a.m. on Friday had one-fifth the concentration of I-131 as the earlier measurement. Three subsequent measurements that morning showed fluctuation. All were below the highest level found at 8:30 a.m. on Friday.

Excellent resource for environmental information regarding radiation

http://www.epa.gov/radiation/

Japanese Nuclear Emergency:  Radiation Monitoring - from the EPA

http://www.epa.gov/radiation/rert/radnet-sampling-data.html

RadNet Laboratory Analysis - from the EPA

http://opendata.socrata.com/Government/RadNet-Laboratory-Analysis/cf4r-dfwe

According to The World Health Organization (WHO), as of March 19 info sharing, it seems unlikely that significant amounts of radiation will affect areas outside of Japan. Rumours are circulating about radiation drifting to other countries. Based on available information, this does not appear to be the case. Exposure to radioactive material released from the affected facilities will be largely limited to the evacuation zone within Japan.

There is therefore currently very little risk for Pacific island countries and territories due to the considerable distances involved, even for the Pacific countries and territories nearest to Japan.

As such, WHO does not currently recommend any measures for persons outside of Japan (including the Pacific island countries and territories) where residents should continue with their normal activities.