Fukushima operators begin risky nuclear fuel rod removal — RT; NHK World video

” In a highly risky undertaking Fukushima plant operators have finally begun removing over 1,500 nuclear fuel rods from one of the four reactors at its damaged nuclear power plant in northeastern Japan on Monday.

During the first transfers of the operation, steel fuel rods were laid in a cooling pool in a damaged reactor building. The portable pool holds 22 rods, with the operation being likened to removing cigarettes from a squashed pack. While the first group will take around two days to move, it could take up to a week to move the cooling pool to a common storage pool in a different building, TEPCO told Reuters.  “We will continue with the work from tomorrow and proceed, paying close attention to safety,” said TEPCO in the statement.

It is important to conduct the transfer as soon as possible as they are being stored in an unstable building which could potentially collapse in the event of another earthquake.

Unit 4 of the Fukushima Daiichi plant was offline at the time of the 2011 catastrophic earthquake and tsunami, which is why, unlike the other three, its core didn’t go into meltdown.

Hydrogen explosions blew the roof off the building and severely damaged the structure, however. Keeping so many fuel rods in a storage pool in the building poses a serious safety risk, experts say.

With the help of robots and cranes, the workers will attempt to cautiously transfer 1,331 spent fuel rods and 202 new ones from the damaged reactor pool to a more reliable storage facility. If these rods break or overheat, radioactive gases could be released into the atmosphere, however, prompting a self-sustained nuclear chain reaction.

According to the operators of the plant, Tokyo Electric Power Co (TEPCO), all necessary measures have been taken to contain the threat stemming from the worst nuclear disaster since Chernobyl.

While the full decommissioning of the plant is expected to take decades, the company said it plans to remove 22 rods over the course of two days. A giant crane equipped with a remote- controlled pincer will be lowered into the pool and hook onto the rods, placing them inside a 91-ton cask which will be loaded on to a trailer and taken to a new storage pool.

Earlier this week it was reported that three of the spent fuel assemblies that will be pulled from the nuclear plant on Monday were in fact damaged before the 2011 earthquake hit the facility. TEPCO said the damaged assemblies – 4.5 meter high racks with 50 to 70 rods of highly irradiated used fuel – wouldn’t be lifted from the plant’s Reactor No. 4, Reuters reported.

In an 11-page information sheet released in August, TEPCO informed that one of the assemblies was actually damaged back in 1982, when it was bent out of shape during a transfer.

Japan’s Nuclear Regulation Authority has assigned an inspector to keep an eye on the dangerous operation, as well as video monitoring of the removal site.

Meanwhile, targets for reducing radiation levels and eradicating nuclear fallout in the areas still haven’t been met, with the radius of evacuation after the Fukushima nuclear meltdown larger than the area of Hong Kong. Some areas will remain contaminated for years to come, experts say. Part of the cleanup plan is to decontaminate the surrounding towns and villages and follow new guidelines by the International Center for Radiological Protection. ”

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Watch NHK World’s video on the start of the fuel rod removal process.

Facts on complex operation to remove Fukushima fuel rods — GlobalPost

” Tokyo Electric Power (TEPCO) on Monday will start removing fuel from a storage pool at Japan’s Fukushima nuclear plant, the most challenging operation since runaway reactors were brought under control two years ago.

Here are some key facts about the operation.

Q: What’s the state of nuclear fuel at the site?

A: Reactors No. 1, 2 and 3 went into meltdown after their cooling systems were knocked out by the March 2011 tsunami. The temperature of the cores and spent fuel pools at all reactors is now stable and water is being used to keep them cool.

Reactor No. 4, whose outer building was damaged by fires and an explosion, has an empty core but a total of 1,533 fuel assemblies — 1,331 spent fuel bundles and 202 unused ones — are in its storage pool.

Q: Why does TEPCO have to take fuel from the pool?

A: According to the firm, it is safer to store all fuel in a shared pool that is reinforced against possible future earthquakes and tsunamis.

This will be the first post-tsunami attempt to move any fuel from one part of the plant to another.

Q: How will the operation work?

A: Under normal circumstances, nuclear plants shuffle fuel rods around fairly frequently, often using computer-controlled robotic arms that “know” exactly where each fuel assembly is.

But the damage to the building housing this pool, along with the presence in the pool of debris from explosions, is a wildcard that will complicate this operation considerably.

Workers in heavy protective equipment will use a remote control to direct a specially installed “grabber” into the pool, where it will latch onto fuel assemblies and drop them into a huge cask.

Each 4.5-metre (15-foot) fuel bundle needs to be kept completely submerged at all times to prevent it from heating up.

Once loaded with assemblies and water, the 91-tonne cask will be lifted out by a different crane and put onto a trailer. It will then be taken to another part of the complex and the process will be reversed.

Removing all 1,500-odd assemblies is expected to take until the end of 2014. Getting this done successfully will mean engineers can then start trying to extricate fuel from the reactors that went into meltdown.

But where the fuel pool operation is tricky and contains a few unknowns, removing fuel from the melted and misshapen cores of reactors 1, 2 and 3 will pose a whole new level of difficulty.

Q. What could go wrong?

A: Each rod contains uranium and a small amount of plutonium. If they are exposed to the air, for example if they are dropped by the grabber, they would start to heat up, a process that, left unchecked, could lead to a self-sustaining nuclear reaction – known as “criticality”.

TEPCO says a single assembly should not reach criticality and the grabber will not carry more than one at a time.

Assemblies exposed to the air would give off so much radiation that it would be difficult for a worker to get near enough to fix it.

Sceptics say with so many unknowables in an operation that has never been attempted under these conditions, there is potential for a catastrophe.

Government modelling in the immediate aftermath of the Fukushima disaster, which was only subsequently made public, suggested that an uncontrolled nuclear conflagration at Fukushima could start a chain reaction in other nearby nuclear plants.

That worst-case scenario said a huge evacuation area could encompass a large part of greater Tokyo, a megalopolis with 35 million inhabitants. ”

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Tepco admits 80 spent fuel assembles had damage before nuclear accident — Fukushima Update

” According to Kahoku Shinpo, a Fukushima local paper, TEPCO admitted on November 15, 2013 that there are 70 fuel assemblies with damaged fuel rods in the Reactor 1 Spent Fuel Pool, located on the operating floor (top floor) of the reactor building whose air radiation levels are measured in millisievert/hour and sievert/hour (first floor).

There are also three such fuel assemblies in the Reactor 2 SFP, and four of them in the Reactor 3 SFP.

Total 80 spent fuel assemblies in the SFPs in Reactors 1 – 4 are damaged.

The damages had been there long before the March 11, 2011 accident, and TEPCO claims it properly notified the national government as they discovered the damages. But the company has come clean in public only now.

Kahoku Shinpo article below suggests that the oldest of such damaged fuels may have been there for 40 years in the Reactor 1 Spent Fuel Pool. (Reactor 1 started generating electricity in 1971.)

Reactor 1 at Fukushima I Nuke Plant is TEPCO’s oldest nuclear reactor; it was entirely the project by General Electric of the US, a turnkey.

From Kahoku Shinpo (11/16/2013):

Fukushima I Nuke Plant Reactor 1 has 70 fuel assemblies damaged before the March 11, 2011 disaster, a quarter of the total spent fuel assemblies [in the Spent Fuel Pool of Reactor 1]

It was revealed on November 15 that 70 fuel assemblies in the Reactor 1 Spent Fuel Pool at Fukushima I Nuclear Power Plant had had damages before the March 11, 2011 earthquake/tsunami.

The damaged assemblies are about one-quarter of the 292 spent fuel assemblies stored in the pool. Technologies to remove damaged fuel haven’t been established, and there are worries that [the revelation] may negatively affect the plan to remove the fuels from Reactor 1 [SFP] starting 2017 and the decommissioning work in general.

TEPCO hadn’t disclosed all the facts until November 15. The company says it had reported to the national government as required.

According to TEPCO, these 70 fuel assemblies had series of problems including leakage of radioactive materials from small [pinhole-size] holes [on fuel rods]. So the company removed them from the reactor and stored in a separate location inside the Spent Fuel Pool.

There are three damaged fuel assemblies inside the Reactor 4 Spent Fuel Pool, where the removal of the fuel assemblies will start on November 18. TEPCO has postponed the removal of the damaged assemblies as it is difficult to remove them in a normal manner.

Other than in the Spent Fuel Pools of Reactor 1 and Reactor 4, the Reactor 2 Spent Fuel Pool has three damaged fuel assemblies, and the Reactor 3 Spent Fuel Pool has four, making the total of damaged fuel assemblies 80. TEPCO will consider the measures such as building a dedicated container for transfer for these damaged fuels.

As to the reason why Reactor 1 has the largest number of damaged fuels, TEPCO says, “Reactor 1 [at Fukushima I Nuke Plant] is the oldest nuclear reactor of our company, and we hear that there were quality control issues when the fuel rods were manufactured and that there were many fuel rods with inferior quality. From Reactor 2 onward, much improvement was done on the fuel rods, and quality improved.”

Reactor 1 at Fukushima I Nuke Plant is the first nuclear reactor for TEPCO, and it started the commercial operation in March 1971.

No major national newspaper has covered this story so far. ”

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Cracks in Tepco’s 3/11 narrative — The Japan Times

Toshio Kimura, a former Tepco plant engineer who worked at Fukushima No. 1 for 12 years, theorizes that the March 2011 earthquake damaged piping before the tsunami, meaning that the facility was seismically unsound to begin with. This article is a bit technical, but it’s worth noting the importance of the credibility of this information for the preposed restart of the Kashiwazaki-Kariwa nuclear power plant in Niigata Prefecture, as well as other nuclear reactors in Japan.

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