unit 4 – which is located outside the containment area — may have begun boiling. By midday NHK TV is reporting white smoke rising from the Fukushima I plant, which officials suggest is likely coming from reactor 3. Shortly afterwards all but a small group of remaining workers at the plant are placed on standby because of the radiation rising to a dangerous level of up to 1 Sv/h. TEPCO temporarily suspended operations at the facility. A TEPCO press release states that workers had been withdrawn at 06:00 because of abnormal noises coming from one of the reactor pressure suppression chambers. Late in the evening Reuters reports that water is being poured into reactors 5 and 6. Thursday, 17 March During the morning Self-Defense Force helicopters drop water four times on the spent-fuel pools of units 3 and 4. They measure radiation field of 3.75 Sv/h above Unit 3. In the afternoon it is reported that the unit 4 spent-fuel pool was filled with water and none of the fuel rods were exposed. Construction work is started to supply a working external electrical power source to all six units of Fukushima I. Starting at 7 pm, police and fire water trucks attempt to spray water into the unit 3 reactor with high pressure hoses. Japanese authorities inform the IAEA that engineers are laying an external grid power line cable to unit 2. After watching the helicopter effort on TV Kazunori Hasegawa, president of Chuo Construction, calls the government and offers the use of his two truck-mounted concrete boom pumps to spray water directly into the reactors. TEPCO did not respond for three days, and then stated it would wait for the arrival of similar pumps obtained elsewhere. Friday, 18 March Tokyo Fire Department dispatches thirty fire engines with 139 fire-fighters and a trained rescue team at approximately 03:00 JST, including a fire truck with a 22-metre water tower. For the second consecutive day, high radiation levels are detected in an area northwest of the damaged Fukushima I nuclear plant at 150 μSv/h. Japanese authorities upgrade INES ratings for cooling loss and core damage at unit 1 to level 5, and issue the same rating for units 2 and 3. The loss of fuel pool cooling water at unit 4 is classified as a level 3. In a 24-hour period ending at 11 am local time, radiation levels near the plant