Wednesday, May 18, 2011

Fukushima was always worse than thought

[Update - 25th]
Meltdowns confirmed at Fukushima reactors
Shinichi Saoshiro,

"Now people are used to the situation. Nothing is resolved, but normal business has resumed in places like Tokyo," said Koichi Nakano, a political science professor at Tokyo's Sophia University.

Nakano said that by confirming the meltdowns now, Tepco may be hoping the news will have less impact. The word "meltdown" has such a strong connotation that when the situation was more uncertain more people would likely have fled Tokyo, he said.

Japan nuclear plant confirms meltdown of two more reactors


[Update - 24th]
Fukushima owners failed to follow emergency manual - report
NZ Herald, 23rd May

It appears likely that the operator of the Fukushima Daiichi nuclear power plant did not follow the procedures to prevent a hydrogen explosion, NHK World reports.

NHK obtained the manual for the No.1 reactor, where the hydrogen blast occurred on March 12th, one day after the tsunami destroyed the reactor's cooling system.

The manual calls for releasing air from the vessel when the pressure is projected to rise to 853 kilopascals - double the operating limit.

The manual NHK has obtained shows that the pressure inside the vessel was close to the level that requires a venting operation 13 hours before the explosion occurred.

But the plant operator, Tokyo Electric Power Company (TEPCO), did not start the operation until 6 and a half hours before the explosion, and the operation was carried out just one and a half hours before the blast because it was hampered by high-level radioactivity.

[Update, 20th May]
Scandals in Japan have a familiar pattern. Revelation is followed by reassurance, which on further disclosure, is soon followed by denial, and dissembling before a scapegoat is produced and symbolically offered up to the public for (hopefully) a ritual cathartic closure. It's a kind of theater.
Japanese nuclear boss quits over $15bn loss
Al Jazeera, 20th May.
"I wanted to take managerial responsibility and bring a symbolic close,'' he told reporters, bowing during the news conference. "We are doing our utmost to settle the crisis."

Tepco also announced it will be permanently shutting down its four damaged reactors at the Fukushima plant.

"Today’s loss figures do not account for the huge amount of compensation that is going to have to be paid out to more than 80,000 people who have been directly affected by the disaster, having to be relocated outside the 20-30km zone," our correspondent said.

Tepco has not made an estimate for the likely cost of compensating all victims. Analyst forecasts have ranged from around $25bn up to $130bn, if the crisis at the nuclear complex drags on.

Tepco president resigns over Japan nuclear crisis
Telegraph (UK), 20th May.
Fuel rods appear to have largely melted at three of the plant's reactors after a March 11 earthquake triggered a tsunami that knocked out cooling systems...

"I am resigning for having shattered public trust about nuclear power, and for having caused so many problems and fears for the people," Mr Shimizu told reporters, bowing in a traditional Japanese apology during a news conference.

Mr Shimizu's resignation was widely anticipated because heads of major Japanese companies are expected to step down to take responsibility for even lesser scandals and problems.
Insurance not withstanding (see BNC comments below) TEPCO shares are now one level above junk bond status as the costs mount.
Moody's cuts Tepco to one notch above junk on compensation plan
Reuters, 16th May.
[end update]

While a prominent Australian based pro nuclear site went in hard and fast (prematurely) extolling the safety of the Fukushima Daiichi nuclear reactor and its operators; decrying any popular press report of dangers as alarmist, two months on a clearer picture begins to emerge.

Several themes were proposed about the failure in the face of the massive earthquake that struck the Tohoku region. But one, which increased in height with time, was that no one could have foreseen the danger presented by the Tsunami. This has now been revealed as false. It was foreseen; TEPCO was warned.

Japan govt body detailed tsunami risks before March 11:documents
Reuters, May 15

A government body conducted analyses on the damage tsunamis of various scale would inflict on a nuclear power plant, according to documents made public on Sunday, adding to allegations that Japan and its largest utility failed to heed warnings.

The latest revelation, reported by the Mainichi daily, emerged as the government prepares to help Tokyo Electric Power (TEPCO) compensate victims of the crisis at the tsunami-crippled nuclear Fukushma Daiichi plant.

The government and Tokyo Electric Power have repeatedly described the combination of the magnitude 9.0 earthquake and the ensuing 15-meter (46.5 foot) tsunami on March 11 as beyond expectations.

The institution affiliated with the Ministry of Economy, Trade and Industry, however, analyzed the dangers of tsunamis ranging from 3 meters to 23 meters in a report originally published in December.

"Our analysis shows that a tsunami of a certain height (some 7 meters in the absence of a seawall and some 15 meters if one were present) or higher would have almost a 100 percent chance of damaging the reactor core...," the Japan Nuclear Energy Safety Organization said in the report.

[presumably this means if the reactor were at or near sea level - as the Fukushima plant is ~10 meters above it]

"We presume a tsunami of at least 7 meters would destroy the functions of a seawater pump and that of at least 15 meters would destroy outside equipment such as an electrical transformer."

Through out the early phase of the disaster BNC continued to claim that no damage had occurred to the containment. Many fancy annotated pictures (the site loves them) with big arrows were posted. In fact investigators are now conducting an inquiry reassessing the time-line of events and now believe that the reactor containment may have been damaged by the earthquake. This is not totally surprising given the size of the earthquake.It also explains the later leaks.

Tokyo Electric: reviewing records of how nuclear crisis unfolded
Reuters, Mon May 16

Japanese officials have said until now that the apparent meltdown in three of the reactors at Fukushima was caused by the loss of power to cooling systems when the tsunami knocked out backup diesel generators.

A finding that the reactors were damaged by the quake itself could complicate the growing debate on the future of nuclear power in Japan at a time when Tokyo is under pressure from local officials to tighten safety standards.

"We want to review the data from the 40 to 50 minutes between the time of the earthquake and when the tsunami struck,"

Kyodo news agency quoted an unnamed source at the utility on Sunday as saying that the No. 1 reactor might have suffered structural damage in the earthquake that caused a release of radiation separate from the tsunami.

The utility said on Sunday that a review of data from March 11 suggested that the fuel rods in the No. 1 reactor were completely exposed to the air and rapidly heating five hours after the quake.

By the next morning - just 16 hours later - the uranium fuel rods in the first reactor had melted down and dropped to the bottom of the pressure vessel, the cylindrical steel container that holds the fuel at the core.

The No. 2 and No. 3 reactors are expected to have gone through a similar process and like No. 1 are leaking most of the water being pumped in a bid to keep their cores cool.

In parliament on Monday, government officials were grilled by an opposition lawmaker over their immediate response to the nuclear crisis.

"We can certainly say that if the venting took place a little earlier, we could have prevented the situation from worsening," Nuclear Safety Commission Chairman Haruki Madarame told parliament.

Both Prime Minister Naoto Kan and Trade Minister Banri Kaieda said that they had instructed Tokyo Electric to go ahead with the venting but that the company had taken time to act.

"We had instructed them to go ahead with the vent and I think Tokyo Electric was trying to do this. Even though we asked them repeatedly to vent, it did not happen and so we decided to issue an order. All of us there, including the prime minister and myself had said it should be done as soon as possible,"

Personally1, this does not completely surprise me. Most Japanese do not live up to the myth of the Samurai. Japan is very hierarchical.

Much is made of the "defense in depth" strategy adopted by nuclear power plants. But defense in depth surely means more than just repeating the same (potentially flawed) subsystem over and over. Two examples. Almost all of the diesel generators were located in the basement. Mainichi Daily termed this a "lack of diversity".

Nuclear power plant disaster highlights importance of diverse safety measures
Mainichi Daily, May 16

After the crisis emerged at the Fukushima No. 1 Nuclear Power Plant, I heard experts lamenting that Japan had multiple safety measures in place but lacked an important factor: diversity.

Take, for example, the power generators at the plant. Altogether there were 13 diesel-powered generators designed to start up in the event of a power cut. Even if some failed, there would be spares. But almost all of these generators were set up in the same way, below ground level...

If the plant had adopted a diverse safety plan and placed some of the generators on higher ground, the situation may have been different. Of course it may not have been the perfect solution, but it seems like the obvious thing to do.

Researchers have in the past warned of the possibility of multiple facilities being crippled by a single cause -- such dangers were pointed out in a lawsuit aiming to halt operations at the Hamaoka Nuclear Power Plant. But why didn't officials count this as a real risk at Fukushima?
Why indeed? Because credentialed promoters of nuclear power are all convinced of the safety of the measures they propose and tend to argue that dissenting views are alarmist. Up until the explosion, the engineers at Chernobyl apparently held the same belief.
One possible underlying cause is that the group promoting nuclear power plants in Japan lacks diversity itself, and is exclusive.
Sound familiar?
In Japan, nuclear power plants have been promoted by a group comprising the government, electric power companies, manufacturers and universities. It is a body propped up by the official stance that Japan's nuclear power plants will not succumb to a major disaster. In the past, when the minority warned of the dangers, this body branded them "anti-nuclear" and dismissed their opinions as "extreme arguments."

But the safety of nuclear power plants is a scientific issue dealing with risks, not a matter of ideology. Scientifically, "absolute safety" is not possible.

Just substitute "Australia", "University of Melbourne" (or at least one of its most prominent graduates, Z. Switkowksi) and "Mining Industry" - which sometimes appears to be the defacto government anyway ;-)

Back to the matter of the water levels. TEPCO has only now, two months after the event, managed to obtain an accurate measurement of the actual water depth in the reactor cores - its not near the top.

I am not an engineer, but losing and not having an operable back up, of perhaps one of THE most important control system sensors for the duration of the disaster does not sound like adequate defense in depth.

More importantly, if true, this means that the technicians running the plant were flying partially blind. A point that was made by previously at The Union of Concerned Scientists after examining pictures of the control room after the event and here.

What does this say about all TEPCOs reassurances of a stable water supply?

Probably LUCK as much as design prevented a worse fate.

Compare these revelations to some of the early cocky statements from BNC.
cold shutdown within a few days
Now anticipated by the end of year.
The nuclear reactor containments were undamaged by the tsunami or earthquake
Obviously wrong.
There will be no breach of containment and no release of radioactivity beyond, at the very most, some venting of mildly radioactive steam to relieve pressure.

3. The only reactor that has a small probability of being ‘finished’ is FD unit 1. And I doubt that, but it may be offline for a year or more.

4 Yes, they are insured. No, the costs won’t be $50 billion, more like <<$1 billion depending on what needs to be repaired, and this will all be on-site work. I am happy to be quoted forever after on the above if I am wrong… but I won’t be. Barry Brooke, 12th March.

All wrong.
The emphasis since has been on radiation deaths, which, if they occur will not be for some time, and difficult to prove.

“Whoever undertakes to set himself up as a judge of Truth and Knowledge is shipwrecked by the laughter of the gods.” Albert Einstein.

1. I lived there for a while.


Anonymous said...

When I lived in Japan, in 1995 there was a fire in an electrical substation in Shinjuku station that resulted in the shutdown of the Yamanote train line - the major subway line loop line around central Tokyo. Why did the backup substation not kick in, you ask? Because it was in a room next to the substation, and was caught in the same fire...sounds like Japanese engineers/designers may have a bit a failing in that regard...

SP said...

Every built system has failure modes. Addressing these and the relative risk depends on the skill and experience of the engineering team - who draw on the known or published cases.

The more complex the system, potentially the larger the number of ways the system can fail. Also, the fewer prior examples of that complex system, the less chance the team have of learning from past examples.

I think this does not unfairly describe the nuclear industry. Its a very difficult and complex undertaking.

Learning is especially hard if you don't think there is a risk!

But to make a somewhat flippant analogy - putting most of the generators where they did is akin to putting all the airbags in the steering wheel.