It is now clear that the second explosion at the Fukushima Dai-ichi plant was at reactor Number 3 on March 14, two days after the first explosion at reactor Number 1. Reactor Number 3 is of special concern because, unlike the other two which use standard uranium fuel, it contains "mixed oxide" or MOX fuel—a mixture of uranium and plutonium reprocessed from spent uranium, and significantly more toxic than standard uranium fuel. Safety concerns have long made MOX reactors controversial, and Number 3 may have already started to melt down.

A second explosion was reported at Japan's stricken Fukushima nuclear power plant early on March 14. The blast apparently came after technicians flooded the overheating reactor Number 1 with seawater in a desperate attempt to bring down dangerous temperatures. Authorities are again saying the steel containment structure was not breached. Like the first blast of March 12, the new incident is said to be a hydrogen explosion. Six people are reported missing in the wake of the blast. CTV reports that power company TEPCO said radiation levels at the plant are 10.65 micro-sieverts—significantly below the limit of 500 micro-sieverts at which a nuclear operator is legally required to file a report to the government. This appears to conflict with news reports yesterday that radiation levels were in excess of 1,015 micro-sieverts per hour. The Los Angeles Times reports that radiation levels had risen above the legal limit before the blast, which is what prompted the attempt to flood the reactor.

It has now been determined that the explosion at the Fukushima Dai-ichi nuclear power plant some 150 kilometers north of Tokyo was actually caused by efforts to avert a meltdown, technicians having taken a calculated risk with a decision to vent radioactive steam from the severely overheated reactor Number 1. The release set off a hydrogen explosion which partially destroyed the outer turbine building. This did relieve some of the pressure that has been building up in the reactor containment core since off-site power was lost due to the earthquake, halting the flow of coolant water. But the reactor has not yet been brought under control. Four workers were injured in the explosion, and three were later hospitalized for ­radiation exposure.

An explosion at the Fukushima Dai-ichi power plant in northern Japan on March 12 blew the roof off one building and destroyed the exterior walls of a crippled reactor, but officials said the steel containment core around the reactor had not been breached, and denied that a major meltdown was imminent. Government officials and executives of Tokyo Electric Power gave what the New York Times called "confusing accounts" of the causes of the explosion and the damage it caused. But the explosion apparently occurred in a structure housing turbines near the No. 1 reactor at the plant rather than inside the reactor itself. The Nuclear and Industrial Safety Agency said serious damage to the containment core was unlikely despite the explosion.

In the wake of the March 10 devastating earthquake and tsunami, which have left perhaps 1,000 dead, Japan's government has for the first time declared a "nuclear emergency." Diesel backup systems ceased functioning at the Fukushima Dai-ichi plant's reactor Number 1, run by the Tokyo Electric Power Company (TEPCO) in Fukushima Prefecture (Tohoku region, north of Tokyo). Temperatures are rising in the reactor, and the government has ordered 2,000 residents within a three-kilometer radius of the plant to evacuate. The plant may have risen to 2.1 times its designed capacity, and authorities are considering a controlled release of radioactive gas and steam to relieve the pressure.

Rain and snow over the past two weeks, together with a huge irrigation effort, appear to have saved much of the wheat crop in northern China from drought, easing fears of imminent shortages. This winter was the driest in perhaps 200 years in parts of China, the world's largest wheat producer. That prompted concerns last month that China might need to sharply increase its usually modest wheat imports—as world food prices are already surging. Global wheat supplies are tight after bad weather in other producers, including Russia and Australia. (NYT, March 7)

Tokyo is preparing to send 100 Self-Defense Force troops to Yonaguni in the Ryukyu Islands, the westernmost point in Japanese territory. The move has prompted protests from the island's residents. Yonaguni is the closest spot of inhabited land to the Senkaku Islands, also claimed by both China and Taiwan, which call them the Diaoyu Islands. (NYT, Feb. 10) Japanese talks with China over a disputed gas field in the Senkakus have broken down, and Tokyo says it suspects Beijing has started drilling in the field. Japan's Prime Minister Naoto Kan appealed to Beijing to return to the table and estabish "mutually beneficial strategic relations." (AFP, Jan. 20) In December, Japan overhauled its defense guidelines, laying plans to purchase five submarines, three destroyers, 12 fighters jets, 10 patrol planes and 39 helicopters. (WSJ, Feb. 12)

Japan's ongoing dispute with Russia over the Kuril Islands has been heating up since November, when Dmitry Medvedev became the first Russian president to visit the contested archipelago. Medvedev's high-profile trip to Kunashir, second-largest of the four disputed islands, has sparked both a regional military build-up and a diplomatic war of words. The dispute over the islands—called the Northern Territories in Japan but seized by the Soviets in August 1945—has prevented Moscow and Tokyo from signing a treaty to officially end their World War II hostilities.