Radiation levels appear to be dropping at Fukushima Daiichi

[Hannah Bell]

Radiation levels are dropping somewhat at Japan's disaster-stricken Fukushima Daiichi nuclear power plant. The government's nuclear safety agency says it will continue to monitor the situation carefully.

The Tokyo Fire Department poured water into the plant's Number 3 reactor for 6.5 hours on Sunday night in a continuing attempt to cool down a storage pool for spent fuel.

The Self-Defense Forces meanwhile shot water into the Number 4 reactor on Sunday, and again on Monday morning.

The Nuclear and Industrial Safety Agency says the operations appear to be paying off to a certain degree, with radiation levels showing a continuous decline since Sunday afternoon.

http://www3.nhk.or.jp/daily/english/21_17.html

Accompanying video shows levels at 2670 microsieverts on sun am, up to 3346 sunday pm, down to 2319 monday am.

[PoliticAverse]

1. Roughly around 400 times world average background radiation.

http://en.wikipedia.org/wiki/Background_radiation

[Hannah Bell]

2. 2319 microsieverts = 2.3 millisieverts (mSv). Av. yearly all-source radiation dose for Americans:

6.2 mSv/year (620 mrem)

http://www.nrc.gov/reading-rm/doc-collections/fact-sheets/bio-effects-radiation.html



The level of natural background radiation varies depending on location, and in some areas the level is significantly higher than average.<5> Such areas include Ramsar in Iran, Guarapari in Brazil, Kerala in India,<6> the northern Flinders Ranges in Australia<7> and Yangjiang in China.<8>

In Ramsar a peak yearly dose of 260 mSv has been reported (compared with 0.06 mSv of a chest radiograph or up to 20 mSv of a CT scan).<9> The highest levels of natural background radiation recorded in the world is from areas around Ramsar, particularly at Talesh-Mahalleh which is a very high background radiation area (VHBRA) having an effective dose equivalent several times in excess of ICRP-recommended radiation dose limits for radiation workers and up to 200 times greater than normal background levels. Most of the radiation in the area is due to dissolved radium-226 in water of hot springs along with smaller amounts of uranium and thorium due to travertine deposits. There are more than nine hot springs in the area with different concentrations of radioisotopes, and these are used as spas by locals and tourists.<10> This high level of radiation does not seem to have caused ill effects on the residents of the area and even possibly has made them slightly more radioresistant, which is puzzling and has been called "radiation paradox".

http://en.wikipedia.org/wiki/Background_radiation.