Saturday, December 17, 2011

Japan declares Fukushima plant stable, but is it?

Questions are raised about decommissioning the six damaged reactors

Japan Prime Minister Noda
Japan Prime Minister Yoshihiko Noda said Friday Dec 16 that the government and TEPCO had regained control of the damaged reactors at Fukushima located about 150 miles north of Tokyo.  In a televised speech to the nation, Noda said, "Today,we have reached a great milestone."

"The reactors are stable, which should resolve one big cause of concern for us all."

However, many nuclear engineering experts immediately raised questions about what the government means by "stable" and pointed out the makeshift cooling system in place now could be wiped out by another earthquake.

The New York Times reported that many of these experts said that Noda's declaration was "premature" because the melted fuel in three of the reactors might remain there for as long as a decade before it is removed for safe disposal.  Japan does not have a high level waste repository.

The statement about the stability of the reactors is based on the measurement of the temperatures inside reactors 1, 2 & 3 all of which are below 100 C, the boiling point of water.  TEPCO said Dec 15 that temperatures inside the reactor pressure vessels ranged from 38-69 C (100-150 F).

Many nuclear engineering experts contacted by the news media in Japan and the U.S. said that the strict definition of cold shutdown is for an intact reactor.  In summary, no one knows how to define it, in regulatory terms, for reactors as badly damaged as the units at Fukushima.

Several experts raised the question of whether the damaged fuel in the reactors might spontaneously go critical again, but others pointed out it isn't in the correct configuration to sustain fission. Also, there is uncertainty whether any of the melted fuel escaped from the reactors into the primary containment structures.  If that turns out to be the case, getting it out will be a more difficult task.

The Japan Atomic Energy Commission said Dec 16 that it could be 10 years before work can begin to retrieve the damaged fuel.  And some experts said that a 30 year decommissioning timetable might be optimistic.

Another factor pointing to a definition of stability is that there are no new airborne radiation releases though significant leaks of radioactive water still make the site a dangerous place to work.  

What Noda wants from his announcement

Nuclear crisis manager
Goshi Hoshono
The political motivations for the announcement appear to address several objectives. The first is to convince provincial government officials throughout Japan to agree to allow the restart of 46 shut down nuclear reactors which supply a large portion of the nation's electricity.

Japan is less than 50% self-sufficient in terms of food production which means it needs high value manufacturing exports to pay for food imports. The electricity provided by the reactors runs the nation's heavy industries and durable goods production. The nation's utilities cannot financially sustain long-term purchases of coal, LNG, and bunker grade oil to produce replacement power.

Second, public anger at TEPCO and the government for mishandling the crisis remains high which is why Noda, and his lead crisis manager Goshi Hoshono, emphasized that declaring the reactors in stable condition is a precursor for allowing some of the 80,000 people evacuated from a 13 mile ring around the plant to go home.

Jonathan Cobb, a spokesman for the World Nuclear Association, told Reuters Dec 16 he expects the evacuation zone to shrink at the government identifies areas that are safe for return of the area's residents.

These two objectives are joined at the hip since images of people returning to their homes in Fukushima province will be a powerful media message to the rest of the country.

Third, Noda wants to convince international trading partners such as Vietnam and Turkey, which are negotiating to buy nuclear reactors from Japan, that they can do so with confidence.  In the U.S. Toshiba is the main vendor for planned construction two new nuclear reactors at the South Texas Project.  The problem for Noda, and Japan's heavy industries, is that they can't expect other nations to buy Japanese nuclear reactors if Japan's utilities can't control them or keep them running at home.

What's missing from this picture?

Part of the Fukushima water
decontamination system
The problem for experts looking at the problem from the outside is that it is not easy to assess how long it will take and what it will cost to decommission all six reactors. Three of the units have heat deformed fuel inside the reactor pressure vessels.

Prime Minister Noda acknowledges the challenges ahead.  He said in his nationwide TV address, "The battle is not over."

Nuclear crisis manager Goshi Hoshona said cleanup of the site could take as long as three decades.

Experts looking at the problem say the immediate threat is that makeshift cooling systems could break down, leak, or worse if a new earthquake caused additional damage to reactor units 1-3.

Japanese robotics experts are working to design remote handling tools to enter the reactor pressure vessels to examine the damage and eventually to retrieve damaged fuel assemblies. Also, the plastic piping that supports the cooling system and the rapidly-built decontamination plant need to be replaced with more permanent metal pipes. Last week it was reported that 45 metric tonnes of radioactive water leaked from the plant.

The cost estimate of decommissioning the site keeps spiraling upwards.  The latest official numbers are in a range of $50-60 billion.  TEPCO is paying compensation of $13 billion to businesses and families affected by the evacuation order.  The government may intervene in the firm's crumbling finances to buy a major stake in it so that the utility will remain solvent enough to supply electricity from its working power generation plants.

Is the government's statement credible?

There is wide public distrust in Japan of the government and TEPCO. This is a major cultural shift for Japanese society. A signifciant concern is whether the food supply is safe.  The public does not understand radiation readings nor the safety limits set by the government which are much lower than U.S. standards.

Food products such as rice, beef, and tea leaves have been reported to have C-137 contamination which has a half-life of about 30 years. However, in some cases the readings have been within regulatory limits. The problem for the government is that any radiation reading sets off public protests.

The road ahead for Noda's government and his successors for at least the next two generations will be to continue to show progress on cleanup and insure that no new radiation is coming from the Fukushima site.  One positive sign of progress is a temporary shell has been completed covering reactor #1 which will help contain any future radiation releases.  Even so, achieving greater control of the site in the short-term could be a very tall order.

Update 12/19/11

Goshi Hoshono tells Bloomberg what he means by "Cold Shutdown."

“We understand that there is a difference between the cold shutdown state for a normal nuclear reactor and the state of cold shutdown that we have achieved at Fukushima Dai-Ichi,” Hosono told reporters in Tokyo. “The goal is to have nuclear fuel where it is kept in a cold state and to ensure that radioactive materials are not emitted. That is the whole point of the cooling system that we have in place.”

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6 comments:

Paul Dickman said...

Dan-

Lots of us who spent time at TMI will tell you that once the water situation is under control, the rest is just difficult.

Decommissioning 3 reactors seems almost impossible but I disagree. The technology we have today for remote handled decommissioning is far superior than 30 years ago.

My prediction is that this is done within 5-7 years and can see no reason why it should take much more than that--maybe even sooner.

Joffan said...

Is that really you, Dan? "Many experts", "some experts", this is the land of MSM balancey nonsense. I don't visit your site to hear regurgitated NYT half-understanding of the issues.

The three wrecked Fukushima reactors are being cooled by double lines with good emergency response plans. "The strict definition of cold shutdown" is an irrelevant distraction that was long ago worked through for this case. Perhaps it was an error of PR to call it by a phrase that could be mistaken for any normal shutdown, but it still is not anything worth making a fuss about.

Any "experts" (and I would like to hear some of their names) who think recriticality is likely in melted fuel should have that "expert" status instantly stricken from them. And the "many experts" worrying about the fuel still being in primary containment are also simply making noise. It sounds like a journalistic trawl result, not a real balance of opinion.

The 45 tonnes of water leaked _inside_ the evaporative condenser building. About 300 liters escaped from the building.

Dan Yurman said...

Paul,

The prediction about the time line for decommissioning isn't mine. It comes from Goshi Hoshono, the Japanese gov;t point man on cleaning up the site.

Dan

Dan Yurman said...

It is my view that the term "cold shutdown" is a PR move and that the site is still essentially a very dangerous place.

As for the citation of experts, there are dozens of people on both sides of the issue. I don't have time to list every one of them. If you want to know who they are, go to Google News and search "cold shutdown."

BTW: I've disputed in the past the claim by experts cited in the NYT that the melted fuel breached the RPV.

It has been my experience that the pro-nuclear community doesn't like to hear bad news expecially from a pro-nuclear blogger. That's too bad because I know you've been reading this blog long enough to realize that I call them like I see them. This is one of those times.

Pete said...

As long as the cooling water keeps leaking out of the reactors and containments and into the turbine buildings, the situation is going to remain difficult. As Paul mentions above, they need to find some way to get the water leakage under control, then they will have a better path towards success.

I have also been reading that groundwater is also leaking into the turbine buildings. As much as 500 tons per day. This is just going to create more of a storage problem for Tepco, in finding some place to store all of that water.

Joffan said...

Don't get me wrong, Dan, if you have bad news just shoot with it.

But this isn't really a bad news article. It's more like finding problems with something that we already knew was problematic. The reactors 1-3 are wrecked to varying degrees - OK, not news. The temperatures are being kept low and controllable - known for a couple of months. The only news, really is that the Japanese government has agreed that the current conditions conform to the previously set conditions for declaring the end of phase 2.

"Japan declares Fukushima plant stable, but is it?" - so, if you would, spell it out for me - what are your major doubts on that score? In particular, how could it become a significant threat to the areas that people might return to?