http://nuclearstreet.com/nuclear_power_i...42702.aspx



Several days after hydrogen explosions tore through three reactor buildings at the tsunami soaked Fukushima Daiichi nuclear plant and a fire damaged a fourth, radiation dose readings in parts of the plant remained dangerously high, Tokyo Electric Power Co. reported.

A map released by the power company Sunday and widely reported in the Japanese media Tuesday showed readings as high as 130 millisieverts (13 REM) per hour outside reactors 1 and 3 in late March. Rubble from the explosion at unit 3 emitted radiation topping 900 millisieverts (90 REM) on March 20, the Asahi Shimbun newspaper reported, with air samples nearby dropping to between 10 and 30 millisieverts (1 abd 3 REM) after it was removed. The dose from debris on another side of the same unit was recorded at 300 millisieverts (30 REM).The dose limit set for workers at the site is 250 millisieverts per year (25 REM).

Remote-controlled heavy equipment has since moved the debris and other rubble to 50 containers in a temporary storage area on-site. TEPCO also has sprayed several areas with chemicals intended to keep dust containing radioactive contaminants from entering the air.

Dose measurements have declined considerably in April, but they remain a challenge to crews attempting to cool reactors and spent-fuel tanks that lost power following Japan’s March 11 earthquake. As of Saturday, dose measurements in the air at 30 spots around the reactors were reported at 10 millisieverts or higher, the Daily Yomiuri newspaper reported. Readings taken on the surface of a hose pumping highly-radioactive water from tunnels and sub-levels of unit 2 ranged from 75 millisieverts to 160 millisieverts near the building converted to store the water.


  f1-sv-20110423-e.pdf (Dimensione: 605.83 KB / Scaricato: 3)