(CNSNews.com) – Japan’s earthquake-induced nuclear emergency worsened Tuesday after a third explosion at a stricken power plant appeared to have caused some damage to the reinforced container around a reactor core. Raised radiation levels were soon being detected in Tokyo, some 150 miles to the south.
Prime Minister Naoto Kan told the nation in a televised address that radiation levels had “risen substantially” following the blast at the No.2 reactor at the Fukushima Daiichi nuclear power plant.
The blasts are attributed to a buildup of explosive hydrogen gas, resulting from overheating that occurred when Friday’s enormous earthquake and tsunami in north-eastern Japan knocked out crucial cooling systems.
Two other units at the plant, reactors No. 1 and No. 3, experienced similar explosions on Saturday and Monday respectively, but in both cases the plant operator reported to the U.N. nuclear watchdog that the essential protective containers had sustained no damage. Although a rise in radiation levels was detected earlier at the No. 1 and No. 3 reactors, it was attributed to the deliberate release of steam to relieve pressure in the containment vessels around the reactors.
Tuesday’s No.2 blast appears to have been more serious, however.
Plant operator Tokyo Electric Power Co. (TEPCO) said the explosion occurred near the “suppression pool,” a water reservoir at the base of the reactor vessel that forms part of the cooling system. Although information is sketchy, the location of the blast raised fears that the containment vessel may have been damaged.
Reinforcing the concerns, Japan’s Nuclear and Industrial Safety Agency reported that radiation levels measured near the plant’s main gate jumped shortly after the explosion to more than eight times the level considered safe for a person to be exposed to over a one-year period.
Kan urged people living 20-30 kilometers (12.4-18.6 miles) of the plant to remain indoors. The area within a 20 kilometer radius was evacuated earlier, following Saturday’s explosion.
He also urged the public to remain calm.
The government ordered a no-fly zone over the plant, within a 30 kilometer radius, the Kyodo news agency reported.
Also Tuesday, the housing at Fukushima Daiichi’s inoperative No. 4 reactor caught fire, although TEPCO later reported that the fire had been extinguished.
The plant has six reactors in total. No. 4, 5 and 6 were not operating at the time of the earthquake and tsunami due to periodic inspections.
The U.S. Navy reported that equipment aboard the USS George Washington, the nuclear-powered aircraft carrier homeported at Yokusuka near Tokyo, had detected elevated radiation levels on Tuesday morning from the stricken Fukushima plant.
As a precautionary measure, the commander of U.S. Naval Forces Japan recommended that personnel attached to the base and a nearby Naval Air Facility limit outdoor activities and secure external ventilation systems.
“These measures are strictly precautionary in nature,” the commander said in a statement. “We do not expect that any United States federal radiation exposure limits will be exceeded even if no precautionary measures are taken.”