(This post is by Peter Morris)
Here’s a roundup of the news surrounding the ongoing Fukushima nuclear crisis.
Politics of Nuclear Power in Japan
A review of Japan's press reaction after the three-month roadmap review for containing and cleaning up the crisis shows mixed views, with considerable scepticism. The Asahi Shimbun newspaper was quite complimentary on progress, despite regular criticism in the past; others were more sceptical, and some highlight that water is still leaking from the plant.
The reactor pressure vessel (that part of the reactor that holds the radioactive core) in the 36 year-old reactor at the Genkai nuclear power plant may have a fault in its manufacture. A study of new data questions the quality of the original steel, casting doubt on the credibility of previous inspections of many reactors.
A 40-year-old reactor is applying for a life-extension – the first since March 11 - and Prime Minister Kan sounds unsympathetic, although it is Japan’s Nuclear and Industrial Safety Agency (NISA) and the Nuclear Safety Commission (NSC) that will decide. In 1996 it was decided that the original 30-40 year lifespan for reactors could be extended to 60 years in some cases.
International Atomic Energy Agency chief Yukiya Amano visited the Fukushima plant and offered the organization's help, saying he would like the IAEA to be more proactive in any future disaster. (This would need a Board decision to expand its mandate and it would remain as a provider of verified information on a crisis – a clear conflict of interest). He welcomed TEPCOs progress on a roadmap to a cold shutdown of the Fukushima reactors.
Life-long thyroid tests for 360,000 young people will be provided and all two million residents of Fukushima prefecture will be questioned on their movements to estimate their individual exposure.
Yashuhiro Nakasone, a big proponent of nuclear power when Prime Minister in the 1980s, suggested Japan should go solar. During his tenure, he is reported to have got US agreement that Japan could produce plutonium and is alleged to have arranged that Japan develop a "virtual" nuclear weapon as a deterrent.
The government nearly raised the allowable dose of radiation for workers at Fukushima to 500 mSv in March, days after raising it from 100 to 250 (international safety regulations suggest a limit of 1mSv for the general public). Prime Minister Kan feared direct US intervention unless workers kept working.
State of the Reactors
Rain from the typhoon made water levels rise in the Fukushima reactors (over 400mm in reactor #1 basement, to its highest level yet, and up to 30mm in some trenches), but the circulating water system has avoided an overflow - the highest trench is 270mm below ground level.
External power was cut at #3 and #4 reactors for several hours while TEPCO tried to find the reason – a surge in the external power lines.
The largest aftershock for months (magnitude 6.2 and only 60km from Fukushima) on 24 July seems to have caused no major problems. The weakened cooling pond at Reactor 4 was already strengthened.
There have been several stoppages in the water decontamination system and new problems have developed. But even at 55% of the target level, it is still ‘cleaning’ 36 tons of water an hour, double the amount being injected for cooling.
It is still unclear when a decision will be made on the return of any evacuees. An intensive cleaning experiment of hotspots in Fukushima City may be a model for other areas (3500 people intensively cleaned some streets and a house in a highly contaminated area, remove weeds and mud etc)
Other Contamination (including human exposure)
The Cesium-contaminated beef story grows bigger daily. The government will buy back meat that has already reached the market and invoice TEPCO sometime later. Nearly 3000 cattle have been sent to the market after eating contaminated hay, in yet another major failure by regulators.
New System for Prediction of Environmental Emergency Dose Information (SPEEDI) fallout maps for the first week of the disaster, based on reactor data up to June were published. Six hundred pages on the website show radioactive substances in the atmosphere, external exposures and ground deposition. Note the maps go offshore as the first plume went southeast.
The health ministry has criticised TEPCO because it cannot track 198 people who have worked at Fukushima (last week they knew of 132 lost people). If TEPCO does not have contact details for them, it could also be breaking anti-terrorism laws.
Sixty-four workers in March and April alone received internal radiation exposure of 50 to 100 millisieverts. Some contractors complain they have not been told in detail about the radiation dangers.
Air-dose rate at one radioactive hotspot 150 kilometers from the plant is as high as in areas 50 kilometers from it: 0.2 to 0.5 uSv/ hr. Data from a wide survey in June was published, and rice hay from the hotspot near Kurihara was well above safe limits.
Maps of the contamination are available here.
UPDATE: This is from Reuters...
Japan's Fukushima Daiichi nuclear plant ranked as one of the most dangerous in the world for radiation exposure years before it was destroyed by the meltdowns and explosions that followed the March 11 earthquake. For five years to 2008, the Fukushima plant was rated the most hazardous nuclear facility in Japan for worker exposure to radiation and one of the five worst nuclear plants in the world on that basis.