Seawater just outside one of Japan”s damaged Fukushima Daiichi reactors registered radiation levels on Wednesday 13 times the previous day”s reading, the operator of the crippled nuclear plant said on Thursday.
Japan”s Tokyo Electric Power Company (TEPCO), said combined Cesium-134 and Cesium-137 readings just outside the damaged No. 2 reactor jumped to 1,200 becquerels per liter on Wednesday, the highest levels recorded since late 2011.
Regulatory limits for Cesium, which emits powerful gamma radiation and is potentially fatal to humans, is 90 bq/liter for Cesium-137 and 60 bq/liter for Cesium-134.
A TEPCO spokesman said the sudden spike in radiation was caused by construction work near the No. 2 building, Reuters reported.
News of the spike in radiation levels is the latest setback this week for TEPCO, which has been harshly criticized for its handling of the nuclear disaster in the wake of the massive quake and tsunami that hit the power station in March 2011, triggering three reactor meltdowns.
On Wednesday, six workers were exposed to radiation after a pipe connected to a contaminated water treatment system was mistakenly detached. Reuters estimates that at least 7 tons of water escaped the system.
Earlier, a worker accidentally switched off a water pump used to channel water into the reactor building.
Crews are using chemicals to fortify the soil around the Fukushima reactor buildings – hundreds of meters from the port entrance that connects to the Pacific Ocean – to prevent contaminated water from flowing into the ocean. The pressure from injecting chemicals into the ground forced contaminated soil out into the port area, the spokesman said.
TEPCO also said Cesium-137 readings just outside the silt fence next to the No.2 reactor increased to160 bq/liter, a number that exceeds the regulatory limit and almost double the previous day’s reading.
Radiation from radioactive water leaking from the plant is mostly confined to the harbor around the facility, officials have said.
TEPCO, which is using hundreds of tons of water in an effort to keep the reactors from overheating, has struggled to contain the buildup of radioactive water at the plant.
The accidents at the Fukushima Daiichi plant, situated 220 km (130 miles) from Tokyo, are fueling doubts over TEPCO”s abilities to oversee a hugely complicated cleanup that is expected to take decades.
Last week, the beleaguered Japanese energy company said 430 liters (113 gallons) of contaminated water had leaked from a storage tank at Fukushima and probably flowed to the ocean.
Meanwhile, Japanese officials have said there is no environmental threat to other countries as radiation will be diluted by the sea. Tokyo, despite lingering concerns over the long-term safety situation at Fukushima, was selected last month to host the 2020 Olympic Games. …
How much radiation is this?
The EPA has established a maximum contaminant level of 4 millirem per year for beta particle and photon radioactivity from man-made radionuclide’s in drinking water.
Iodine-131 = 3piC/L (0.11 Bq/L)
Cesium-137 = 200 picocuries per liter (7.41 Bq/L)
Stronium-90 = 8 picocuries per liter. (0.30 Bq/L)
Technetium-99 = 900 picocuries per liter (33.3 Bq/L)
Tritium = 20,000 picocuries per liter (741 Bq/L)
Uranium-238 = 30 µg/L (micrograms/liter)
Iodine-129 = 3 picocuries per liter (0.11 Bq/L)
Milk = 170 Bq/kg (of iodine-131)
FDA has set a Derived Intervention Level (DIL) for Iodine-131 of 170 Bq/kg in foods prepared for consumption.
*All except Iodine-131 found here: http://www.ecy.wa.gov/programs/nwp/gwcontaminants.htm
Iodine-131 and milk/food max statistic found here:
The maximum allowed amount of exposure in a year to Tritium is pretty high compared to other radioactive sources. Why is that?
Since tritium is a low energy beta emitter, it is not dangerous externally (its beta particles are unable to penetrate the skin), but it can be a radiation hazard when inhaled, ingested via food or water, or absorbed through the skin. HTO has a short biological half-life in the human body of 7 to 14 days, which both reduces the total effects of single-incident ingestion and precludes long-term bioaccumulation of HTO from the environment. Biological half life of tritiated water in human body, which is a measure of body water turn over, varies with season. Studies on biological half life of occupational radiation workers for free water tritium in the coastal region of Karnataka, India show that the biological half life in winter season is twice that of the summer season.
Every exposure to ionizing radiation is a roll of the dice, so avoid it when you can.