By Rajaram Panda
In the wake of the massive earthquake that struck on 11 March and as the number of people confirmed dead or missing keeps mounting, Japan is coping with another menace that is beyond imagination. Even as the Meteorological Agency upgraded the magnitude of the earthquake from the original 8.8 to 9, the news that the quake has damaged several nuclear power reactors, forcing the authorities to shut them down thus disrupting electricity power supplies is worrisome. In an emergency situation of this nature, diesel generators are supposed to kick in to power an emergency core cooling system to prevent a meltdown of the nuclear reactor. But since the diesel generators were swamped by the tsunami and therefore failed, the door to a meltdown was opened with the resultant risk of radioactive materials being released into the environment. This is the scenario that Japan is struggling to cope with.
Japan’s biggest nuclear crisis is worsening by the day. Four of the six reactors at the Fukushima No. 1 nuclear power plant have experienced hydrogen explosions since the historic earthquake hit the Tohoku region on 11 March. Fukushima No. 1 nuclear plant suffered a dangerous radiation leak after two new explosions and a fire.
The country is now in a state of panic as the nuclear threat continues to intensify and even spread. Radiation levels have reportedly risen four-fold after a fresh explosion at Fukushima’s reactor No. 4. There is, however, no confirmation on whether the nuclear reactor vessel has been damaged. Another quake of 6 magnitude shook Kanto region on the evening of 15 March, but Japan was spared another tsunami and another bout of devastation. Authorities have issued travel warnings with a view to containing further possible human tragedy.
Tohoku Electric Power Co. has said that it will implement electricity rationing in north-eastern Japan from 17 March to grapple with power shortages in the wake of the killer earthquake, a day after Tokyo Electric Power Co. (Tepco) took such an unprecedented measure in areas near the capital. The situation continued to worsen when news came from the World Meteorological Organisation (WMO) that winds are dispersing radioactive materials over the Pacific Ocean, though away from Japan and other Asian countries.
Tepco evacuated 750 of its employees from the Daiichi nuclear plant site, leaving behind only 50 to pump seawater into the reactor cores in a desperate race to cool down three of the four reactors and prevent their meltdowns. In an emergency meeting called on 15 March, Chief Cabinet Secretary Yukio Edano admitted that there is a risk of three of the four crippled reactors suffering a meltdown. Experts say that such a scenario is possible, though they rule out a repeat of the 1986 Chernobyl-type core meltdown. Professor Kazuhiko Maekawa of Tokyo University, a counsellor at the Nuclear Safety Research Association, has noted that even if the fuel rods melt down they would remain in a liquid state. Further, if the primary reactor containment vessels “are not totally destroyed,” lethal radioactive materials would remain within the reactor compound.” Fukushima has ruled out a Chernobyl-type explosion, which “spread nuclear materials containing ‘death ash’ and contaminated many people.”
Technically, if the effort to prevent a melt down were to be successful, the possibility of large-scale radioactive contamination becomes low. But after the suppression chamber of the No. 2 reactor’s containment vessel failed, fears have heightened over whether the containment vessel itself might be compromised.
A radioactivity monitoring post near the No. 3 reactor showed radiation levels of 400 millisieverts per hour, 400 times the amount an ordinary person is allowed to be exposed during a year. By the afternoon of 12 March, it was confirmed that the nuclear fuel inside the reactor core has partially melted. The radiation level between No. 2 and No. 3 reactors has been reported at 100 millisieverts per hour. Edano admitted that this amount would have a harmful effect on the human body. According to the Institute of Applied Energy, radiation exposure of 7,000 to 10,000 millisieverts per hour is considered a lethal dose. A millisievert is 1,000 microsieverts.
The radiation release was triggered by a hydrogen explosion at the No.4 reactor, which later caught fire. The reactor had been shut down for a regular check when the earthquake struck. But the spent fuel stored inside heated up and generated hydrogen, which was the apparent cause of the explosion. In a desperate move to lower the temperature inside the reactor pressure vessels, Tepco injected sea water into the reactor cores, trying to cool the heating fuel rods inside. Yet, a meltdown is feared to have been occurring in the No. 2 reactor due to a loss of coolant.
Despite frenetic efforts, the No. 2 reactor’s fuel rods became fully exposed for over two hours, threatening a meltdown. Even when sea water was pumped in, only the bottom half of the fuel rods were covered. And soon the water level dropped again thus fully exposing the fuel rods for a second time. Hydrogen explosions at the Nos. 1, 2 and 3 reactors, which blew up their housings, all came after their cooling systems failed.
Prime Minister Kan Naoto has admitted that the possibility of a further radioactive leak is increasing. The radiation leak prompted the government to order residents within a radius of 20 km to 30 km to stay indoors to prevent exposure. On 14 March alone some 180,000 people living within a 20-km radius of 1F were evacuated. Twenty-two of the evacuees were exposed to radiation.
The government was displeased by Tepco’s slow reporting to the Prime Minister’s office and set up a joint crisis headquarters at the utility’s head office in Tokyo. Prime Minister Kan admitted that the situation is worrisome but assured the people that his government will spare no effort to overcome the crisis. Kan offered to “take the lead” on this gigantic task and promised to “resort to every possible means to prevent the damage from spreading.” According to Gregory Jaczko, chairman of the US Nuclear Regulatory Commission, Japan has asked the US to provide more equipment to help deal with the crisis.
The government declared a “nuclear emergency situation” for the first time ever, destroying the credibility of the claim by the government and electric power industry hitherto that nuclear power generation is safe. The events in Fukushima nuclear power plants showed that the government and the power industry failed to implement necessary safeguards. In a scathing editorial titled “Nuclear power in disarray”, The Japan Times asked, “why were the back-up diesel generators at 1F placed in a location where they would be vulnerable in the event of a tsunami, and why wasn’t a policy of double-redundancy enforced in which a reliable back-up power-generation system existed for the back-up diesel generators? Considering the potential for disaster, which has now become a grave reality, it is mind-boggling that such flawed policies were in place.” Its counsel to the government was: “Japan’s nuclear power generation policy must be strictly reviewed. The government and power companies should thoroughly inspect the nation’s 54 power reactors and implement upgrades as needed to ensure multiple redundancies in safety systems. Finally, the government should continuously update the public with accurate information as the current situation develops.”
Originally published by Institute for Defence Studies and Analyses (www.idsa.in) at http://www.idsa.in/idsacomments/JapanFacesaNuclearDisaster_rpanda_180311