As a comparison: Chernobyl was one reactor, in a rural area, a quarter of the size of one of the reactors at Fukushima. There was no 'spent fuel pool' to worry about. Chernobyl was treated in-situ...meaning everything was pretty much left where it was while the effort to contain it was made (and very expeditiously I might add) not only above ground, but below ground. At Fukushima, we have six top-floor pools all loaded with fuel that eventually will have to be removed, the most important being Reactor 4, although Reactor 3 is in pretty bad shape too.

http://www.zerohedge.com/news/2013-08-17/radioactive-water-leaking-fukushima-what-we-know Scientists on both sides of the Pacific have measured changing levels of radioactivity in fish and other ocean life since the March 2011 earthquake and tsunami triggered a nuclear meltdown at Japan’s Fukushima Daiichi nuclear plant. On Aug. 2, 2013, when Japan’s Tokyo Electric Power Co. (TEPCO) gave its first estimate of how much radioactive water from the nuclear plant has flowed into the ocean since the disaster, the company was finally facing up to what scientists have recognized for years.

"As an oceanographer looking at the reactor, we've known this since 2011," said Ken Buesseler, a marine chemist at the Woods Hole Oceanographic Institute in Woods Hole, Mass. "The news is TEPCO is finally admitting this."

TEPCO estimated that between 20 trillion and 40 trillion becquerels (units of radioactivity representing decay per second) of radioactive tritium have leaked into the ocean since the disaster, according to the Japanese newspaper Asahi Shimbun. The Fukushima plant is still leaking about 300 tons of radioactive water into the ocean every day, according to Japanese government officials. [Infographic: Inside Japan's Nuclear Reactors]

Japan is haunted by two lingering questions from this aftermath of the disaster: First, how the radioactivity might seriously contaminate ocean life that represents a source of seafood for humans; second, whether it can stop the leaks of radioactive water from the Fukushima plant.

Radioactivity is not created equal

The Fukushima plant is leaking much less contaminated water today compared with the immediate aftermath of the nuclear meltdown in June 2011 — a period when scientists measured 5,000 to 15,000 trillion becquerels of radioactive substances reaching the ocean. Even if radioactivity levels in the groundwater have spiked recently, as reported by Japanese news sources, Buesseler expects the overall amount to remain lower than during the June 2011 period.

"The amount of increase is still much smaller today than it was in 2011," Buesseler told LiveScience. "I'm not as concerned about the immediate health threat of human exposure, but I am worried about contamination of marine life in the long run."

The biggest threat in the contaminated water that flowed directly from Fukushima's reactors into the sea in June 2011 was huge quantities of the radionuclide called cesium. But the danger has changed over time as groundwater became the main source for leaks into the ocean. Soil can naturally absorb the cesium in groundwater, but other radionuclides, such as strontium and tritium, flow more freely through the soil into the ocean. (TEPCO is still coming up with estimates for how much strontium has reached the ocean.)

Tritium represents the lowest radioactive threat to ocean life and humans compared with cesium and strontium. Cesium’s radioactive energy is greater than tritium, but both it and tritium flow in and out of human and fish bodies relatively quickly. By comparison, strontium poses a greater danger because it replaces the calcium in bones and stays for much longer in the body.

Not fishing for trouble

A number of fish species caught off the coast of the Fukushima Prefecture in 2011 and 2012 had levels of cesium contamination greater than Japan's regulatory limit for seafood (100 becquerels per kilogram), but both U.S. and Japanese scientists have also reported a significant drop in overall cesium contamination of ocean life since the fall of 2011. The biggest contamination risks came from bottom-dwelling fish near the Fukushima site.

The radioactive groundwater leaks could still become worse in the future if TEPCO does not contain the problem, U.S. scientists say. But they cautioned against drawing firm conclusions about the latest impacts on ocean life until new peer-reviewed studies come out.

"For fish that are harvested 100 miles [160 kilometers] out to sea, I doubt it’d be a problem," said Nicholas Fisher, a marine biologist at Stony Brook University in Stony Brook, N.Y. "But in the region, yes, it's possible there could be sufficient contamination of local seafood so it'd be unwise to eat that seafood."

The overall contamination of ocean life by the Fukushima meltdown still remains very low compared with the effects of naturally occurring radioactivity and leftover contamination from U.S. and Soviet nuclear weapons testing in the 1960s. Fisher said he’d be "shocked" if the ongoing leaks of contaminated water had a significant impact on the ocean ecosystems.

Source of radioactive water

TEPCO is facing two huge issues in stopping the radioactive water leaks. First, groundwater from nearby mountains is becoming contaminated as it flows through the flooded basements of the Fukushima plant's reactor buildings. The water empties into the nuclear plant's man-made harbor at a rate of about 400 tons per day — and TEPCO has struggled to keep the water from leaking beyond existing barriers into the ocean.

"This water issue is going to be their biggest challenge for a long time," said Dale Klein, former head of the U.S. Nuclear Regulatory Commission. "It was a challenge for the U.S. during Three Mile Island [a partial nuclear meltdown in Pennsylvania on March 28, 1979], and this one is much more challenging."

Second, TEPCO must also deal with contaminated water from underground tunnels and pits that hold cables and pipes for the Fukushima nuclear plant’s emergency systems. The underground areas became flooded with highly radioactive water during the initial meltdown of the Fukushima plant’s reactors, and have since leaked water into the ocean despite TEPCO’s efforts to seal off the tunnels and pits.

TEPCO has also been racing to deal with the problem of storing hundreds of thousands of tons of radioactive water from the Fukushima plant, said Hiroaki Koide, a nuclear engineer at Kyoto University in Japan. The Japanese utility is testing a water decontamination system called ALPS that can remove almost all radioactive substances except for tritium, but has put much of the contaminated water in storage tanks in the meantime.

"The tanks are an emergency solution that is not suitable for long-time storage," Koide said. "Water will leak from any tank, and if that happens, it will merge with the groundwater."

What must be done

So what solutions exist beyond building more storage tanks? Klein reviewed a number of possible solutions with TEPCO when he was picked to head an independent advisory committee investigating the Fukushima nuclear accident.

One possible solution involves using refrigerants to freeze the ground around the Fukushima plant and create a barrier that stops the inflow of groundwater from the mountains. TEPCO is also considering a plan to inject a gel-like material into the ground that hardens into an artificial barrier similar to concrete, so that it can stop the contaminated groundwater from flowing into the ocean.

Such barriers could help hold the line while TEPCO pumped out the water, treated it with purification systems such as ALPS, and then figured out how to finally dispose of the decontaminated water.

"My priority would be stop the leak from the tunnel immediately," Klein said. "Number two would be to come up with a plan to stop the inflow and infiltration of groundwater. Number three is to come up with an integrated systematic water treatment plan."

Meanwhile, both Japanese and U.S. scientists continue to gather fresh scientific data on how the radioactivity impacts ocean life. Despite low contamination levels overall, studies have shown great differences in certain species depending on where they live and feed in the ocean.

"The most straightforward thing the Japanese can do now is measure the radionuclides in fish tissue, both at the bottom of the ocean and up in the water column at different distances from the release of contaminated groundwater," Fisher said.

Finally, what is the worst case scenario? What level of contamination are we looking at and how dire would the consequences be for the long-term health of the region?

CC: Extremely dire. This is a terrible answer to have to give, but the worst case scenario could play out in death to billions of people. A true apocalypse. Since we have been discussing Reactor 4, I'll stick to that problem in particular, but also understand that a weather event, power outage, earthquake, tsunami, cooling system failure, or explosion and fire in any way, shape, or form, at any location on the Fukushima site, could cascade into an event of that magnitude as well.

At any time, following any of these possible events, or even all by itself, nuclear fuel in reactor 4's pool could become critical, mostly because it will heat up the pool to a point where water will burn off and the zirconium cladding will catch fire when it is exposed to air. This already happened at least once in this pool that we are aware of. It almost happened again recently after a rodent took out an electrical line and cooling was stopped for days.

Once the integrity of the pool is compromised that will likely lead to more criticalities, which then can spread to other fuel. The heat from this reaction would weaken the structure further, which could then collapse and the contents of the pool end up in a pile of rubble on the ground. This would release an enormous amount of radioactivity, which Arnie Gundersen has referred to as a “Gamma Shine Event” without precedence, and Dr. Christopher Busby has deemed an “Open-air super reactor spectacular.”

This would preclude anyone from not only being at Reactor 4, but at Reactors 1, 2, 3, 5, 6, the associated pools for each, and the common spent fuel pool. Humans could no longer monitor and continue cooling operations at any of the reactors and pools, thus putting the entire site at risk for a massive radioactive release.

Mathematically, it is almost impossible to quantify in terms of resulting contamination, and a separate math problem would need to be performed for every nuclear element contained within the fuel, and whether or not that fuel exploded, burned, fissioned, melted, or was doused with water to try to cool it off and poured into the ocean afterward.

Some researchers have even ventured to say that other nuke plants on the east coast of Honshu may need to be evacuated if levels get too high, which will lead to subsequent failures/fires and explosions at these plants as well. Just how profound the effect will be on down-winders in North America, or the entire northern hemisphere for that matter, will literally depend on where the wind blows and where the rain falls, the duration and extent of a nuclear fire or chain-reaction event, and whether or not that reaction becomes self-sustaining. At least the northern half of Japan would be uninhabitable, and some researchers have argued that it already is.

This is already happening to the nuclear fuel in the ground under the plant, but now it would be happening above ground as well. There is no example historically to draw from on a scale of this magnitude. Everything is theory. But anyone who says this can't happen is not being truthful, because nobody really knows how bad things could get.

The most disturbing part of all of this is that Fukushima has been this dangerous, and precarious, since the second week of March 2011. The ante will definitely be upped once the fuel removal starts.

-------------------------------------------------------------------------------- There's more: RT interviews fallout researcher Christina Consolo, who says that if Japan continues on its course of doing nothing, then years of "duct tape fixes" could result in millions of death. Some excerpts: RT: How serious is the fuel rod situation compared to the danger of contaminated water build-up which we already know about? Christina Consolo: Although fuel rod removal happens on a daily basis at the 430+ nuclear sites around the world, it is a very delicate procedure even under the best of circumstances. What makes fuel removal at Fukushima so dangerous and complex is that it will be attempted on a fuel pool whose integrity has been severely compromised. However, it must be attempted as Reactor 4 has the most significant problems structurally, and this pool is on the top floor of the building. There are numerous other reasons that this will be a dangerous undertaking. - The racks inside the pool that contain this fuel were damaged by the explosion in the early days of the accident. - Zirconium cladding which encased the rods burned when water levels dropped, but to what extent the rods have been damaged is not known, and probably won't be until removal is attempted. - Saltwater cooling has caused corrosion of the pool walls, and probably the fuel rods and racks. - The building is sinking. - The cranes that normally lift the fuel were destroyed. - Computer-guided removal will not be possible; everything will have to be done manually. - TEPCO cannot attempt this process without humans, which will manage this enormous task while being bombarded with radiation during the extraction and casking. - The process of removing each rod will have to be repeated over 1,300 times without incident. - Moving damaged nuclear fuel under such complex conditions could result in a criticality if the rods come into close proximity to one another, which would then set off a chain reaction that cannot be stopped. What could potentially happen is the contents of the pool could burn and/or explode, and the entire structure sustain further damage or collapse. This chain reaction process could be self-sustaining and go on for a long time. This is the apocalyptic scenario in a nutshell. The water build-up is an extraordinarily difficult problem in and of itself, and as anyone with a leaky basement knows, water always 'finds a way.’ At Fukushima, they are dealing with massive amounts of groundwater that flow through the property, and the endless pouring that must be kept up 24/7/365 to keep things from getting worse. Recently there appears to be subsidence issues and liquefaction under the plant. TEPCO has decided to pump the water out of these buildings. However, pumping water out of the buildings is only going to increase the flow rate and create more of these ground issues around the reactors. An enormous undertaking - but one that needs to be considered for long-term preservation of the integrity of the site - is channelling the water away, like a drain tile installed around the perimeter of a house with a leaky basement, but on an epic scale. Without this effort, the soils will further deteriorate, structural shift will occur, and subsequently the contents of the pools will shift too. Any water that flows into those buildings also becomes highly radioactive, as it is likely coming into contact with melted fuel. Without knowing the extent of the current liquefaction and its location, the location of the melted fuel, how long TEPCO has been pumping out water, or when the next earthquake will hit, it is impossible to predict how soon this could occur from the water problem/subsidence issue alone. But undoubtedly, pumping water out of the buildings is just encouraging the flow, and this water problem needs to be remedied and redirected as soon as possible. RT: Given all the complications that could arise with extracting the fuel rods, which are the most serious, in your opinion? CC: The most serious complication would be anything that leads to a nuclear chain reaction. And as outlined above, there are many different ways this could occur. In a fuel pool containing damaged rods and racks, it could potentially start up on its own at anytime. TEPCO has been incredibly lucky that this hasn't happened so far. My second biggest concern would be the physical and mental fitness of the workers that will be in such close proximity to exposed fuel during this extraction process. They will be the ones guiding this operation, and will need to be in the highest state of alertness to have any chance at all of executing this plan manually and successfully. Many of their senses, most importantly eyesight, will be hindered by the apparatus that will need to be worn during their exposure, to prevent immediate death from lifting compromised fuel rods out of the pool and placing them in casks, or in the common spent fuel pool located a short distance away. Think for a moment what that might be like through the eyes of one of these workers; it will be hot, uncomfortable, your senses shielded, and you would be filled with anxiety. You are standing on a building that is close to collapse. Even with the strongest protection possible, workers will have to be removed and replaced often. So you don't have the benefit of doing such a critical task and knowing and trusting your comrades, as they will frequently have to be replaced when their radiation dose limits are reached. If they exhibit physical or mental signs of radiation exposure, they will have be replaced more often. It will be one of the worst, but most important jobs anyone has ever had to do. And even if executed flawlessly, there are still many things that could go wrong. RT: How do the potential consequences of failure to ensure safe extraction compare to other disasters of the sort – like Chernobyl, or the 2011 Fukushima meltdown? CC: There really is no comparison. This will be an incredibly risky operation, in the presence of an enormous amount of nuclear material in close proximity. And as we have seen in the past, one seemingly innocuous failure at the site often translates into a series of cascading failures. Many of their 'fixes' are only temporary, as there are so many issues to address, and cost always seems to be an enormous factor in what gets implemented and what doesn't. As a comparison: Chernobyl was one reactor, in a rural area, a quarter of the size of one of the reactors at Fukushima. There was no 'spent fuel pool' to worry about. Chernobyl was treated in-situ...meaning everything was pretty much left where it was while the effort to contain it was made (and very expeditiously I might add) not only above ground, but below ground. At Fukushima, we have six top-floor pools all loaded with fuel that eventually will have to be removed, the most important being Reactor 4, although Reactor 3 is in pretty bad shape too. Spent fuel pools were never intended for long-term storage, they were only to assist short-term movement of fuel. Using them as a long-term storage pool is a huge mistake that has become an 'acceptable' practice and repeated at every reactor site worldwide. We have three 100-ton melted fuel blobs underground, but where exactly they are located, no one knows. Whatever 'barriers' TEPCO has put in place so far have failed. Efforts to decontaminate radioactive water have failed. Robots have failed. Camera equipment and temperature gauges...failed. Decontamination of surrounding cities has failed. We have endless releases into the Pacific Ocean that will be ongoing for not only our lifetimes, but our children’s' lifetimes. We have 40 million people living in the Tokyo area nearby. We have continued releases from the underground corium that reminds us it is there occasionally with steam events and huge increases in radiation levels. Across the Pacific, we have at least two peer-reviewed scientific studies so far that have already provided evidence of increased mortality in North America, and thyroid problems in infants on the west coast states from our initial exposures. We have increasing contamination of the food chain, through bioaccumulation and biomagnification. And a newly stated concern is the proximity of melted fuel in relation to the Tokyo aquifer that extends under the plant. If and when the corium reaches the Tokyo aquifer, serious and expedient discussions will have to take place about evacuating 40 million people from the greater metropolitan area. As impossible as this sounds, you cannot live in an area which does not have access to safe water. The operation to begin removing fuel from such a severely damaged pool has never been attempted before. The rods are unwieldy and very heavy, each one weighing two-thirds of a ton. But it has to be done, unless there is some way to encase the entire building in concrete with the pool as it is. I don't know of anyone discussing that option, but it would seem much 'safer' than what they are about to attempt...but not without its own set of risks. And all this collateral damage will continue for decades, if not centuries, even if things stay exactly the way they are now. But that is unlikely, as bad things happen like natural disasters and deterioration with time...earthquakes, subsidence, and corrosion, to name a few. Every day that goes by, the statistical risk increases for this apocalyptic scenario. No one can say or know how this will play out, except that millions of people will probably die even if things stay exactly as they are, and billions could die if things get any worse.