Kyodo News is a respected nonprofit agency based in Tokyo, and it distributes news to just about all newspapers and tv networks in Japan. It’s interesting to compare Kyodo News latest status report on the reactors at Fukushima Daiichi plant (see here) with that of the International Atomic Energy Agency (see here), whose status report was also released today. Here’s what the IAEA says about each reactor, followed by what Kyodo News says, in italics…
Unit 1 experienced an explosion on 12 March that destroyed the outer shell of the building’s upper floors. No precise information has been available on the status of the spent fuel pool.
– Reactor No. 1 (Operation suspended after quake)
Partial melting of core, cooling failure, vapor vented, building housing containment of reactor damaged by hydrogen explosion, roof blown off, seawater being pumped in.
No precise information has been available on the status of the spent fuel pool. Authorities began adding 40 tonnes of seawater to the spent fuel pool on 20 March.
– Reactor No. 2 (Operation suspended after quake)
Damage to reactor containment structure feared, cooling failure, seawater being pumped in, fuel rods fully exposed temporarily, vapor vented, building housing containment of reactor damaged by blast at adjacent reactor No. 3, blast sound heard near suppression chamber of containment vessel, seawater pumped into pool holding spent-fuel rods on Sunday, access to external power restored Sunday.
Unit 3 experienced an explosion on 14 March that destroyed the outer shell of the building’s upper floors. The blast may have damaged the primary containment vessel and the spent fuel pool. Concerned by possible loss of water in the pool, authorities began spraying water into the building in an effort to replenish water levels. First, helicopters dropped seawater on 17 March, and every day since then, including today, emergency workers have sprayed water from fire trucks and other vehicles.
– Reactor No. 3 (Operation suspended after quake)
Partial melting of core feared, cooling failure, vapor vented, seawater being pumped in, building housing containment of reactor badly damaged by hydrogen explosion, seawater dumped over spent-fuel storage pool by helicopter Thursday, water sprayed at it from ground for four days in a row through Sunday.
This reactor was shut down 30 November 2010 for routine maintenance, and all the fuel assemblies were transferred from the reactor to the spent fuel pool, before the 11 March earthquake. The heat load in this pool is therefore larger than the others.
On 14 March, the building’s upper floors were severely damaged, possibly causing a reduction of cooling capability in the spent fuel pool. Emergency workers began spraying water into the building today.
– Reactor No. 4 (Under maintenance when quake struck)
Renewed nuclear chain reaction feared at spent-fuel storage pool, fire at building housing containment of reactor Tuesday and Wednesday, only frame remains of reactor building roof, temperature in the pool reached 84 C on March 14, water sprayed at pool on Sunday.
Unit 5 and 6
Instrumentation at these reactors began to indicate rising temperatures at their spent fuel pools starting on 14 March. Three days later, Japanese technicians successfully started an emergency diesel generator at Unit 6, which they used to provide power to basic cooling and fresh-water replenishment systems. Workers created holes in the rooftops of both buildings to prevent any hydrogen accumulation, which is suspected of causing earlier explosions at Units 1 and 3.
– Reactor No. 5 (Under maintenance when quake struck)
Some fuel rods left in reactor core, cooling in spent-fuel storage pool resumed Saturday, cold shutdown at reactor on Sunday.
– Reactor No. 6 (Under maintenance when quake struck)
Some fuel rods left in reactor core, emergency power generator and cooling functions restored Saturday, cold shutdown at reactor on Sunday.
Please note that the Kyodo News report on reactor No.4 only says “Renewed nuclear chain reaction feared at spent-fuel storage pool”. Criticality, the fission process starting again, can only occur when fuel rods are stored too close together, which appears to be the case with the cooling pool of reactor No.4.
Latest reports are that it might be another week before they can restore power to reactors 3 and 4 (see here). This seems to be because of the large amount of radiation coming out of the reactor 3 building (it’s too dangerous to get anywhere near it). It looks like this radiation is going to be released into the environment for many days yet, and this is the best case scenario: that they get the Fukushima Daiichi plant under control, and the surrounding area will be uninhabitable for many decades.