Guest post by David Middleton
Radiation levels recorded inside Fukushima’s crippled nuclear power station are at the highest levels since its catastrophic meltdown in 2011.
Tokyo Electric Power Co. Holdings Inc (Tepco) said the radiation level in the containment vessel of Reactor 2 in the Fukushima No 1 power plant had reached a maximum of 530 sieverts per hour, Japan Times reports.
The “unimaginable” radiation levels were assessed by the National Institute of Radiological Sciences.
According to the institute, just 4 sieverts of radiation exposure would be enough kill a handful of people.
Fake News Item #1: “Unimaginable radiation levels.”
“Tokyo Electric Power Co. Holdings Inc (Tepco) said the radiation level in the containment vessel of Reactor 2 in the Fukushima No 1 power plant had reached a maximum of 530 sieverts per hour, Japan Times reports.
The ‘unimaginable’ radiation levels were assessed by the National Institute of Radiological Sciences.”
530 Sv/hr… “unimaginable”? I don’t think so…
High-level wastes are hazardous because they produce fatal radiation doses during short periods of direct exposure. For example, 10 years after removal from a reactor, the surface dose rate for a typical spent fuel assembly exceeds 10,000 rem/hour – far greater than the fatal whole-body dose for humans of about 500 rem received all at once.
530 Sv = 53,000 rem.
If “10 years after removal from a reactor, the surface dose rate for a typical spent fuel assembly exceeds 10,000 rem/hour,” 530 Sv/hr is not “unimaginable.” I would venture a guess that 530 Sv/hr would be well within the expected range inside a reactor core, loaded with hot fuel which had suffered at least a partial meltdown.
Fake News Item #2: “The radiation level in the containment vessel… had reached 530 sieverts per hour.”
The use of the phrase “had reached” clearly implies that radiation levels had risen. Other reports citing a previous high of 72 Sv/hr were also clearly intended to convey the impression that radiation levels had risen over the past 5-6 years. This is clearly fake news…
NO, RADIATION LEVELS AT FUKUSHIMA DAIICHI ARE NOT RISING
Saturday February 4th, 2017
— Yes, TEPCO has measured very high radiation inside Daichi Unit 2.
— No, it does’t mean radiation levels there are rising.
In response to visual investigation results and high radiation measurements recently taken by TEPCO inside Fukushima Daiichi Unit 2, many news outlets have published stories with headlines like “Fukushima nuclear reactor radiation at highest level since 2011 meltdown.” (The Guardian, Feb. 3, 2017).
This has led to a number of alarming stories claiming that radiation at Daiichi has “spiked” to unprecedented levels. That’s not what the findings indicate, however. In addition, Safecast’s own measurements, including our Pointcast realtime detector system have shown radiation levels near Daiichi to be steadily declining. As described in the Safecast Report, Vol.2, Section 2.1.4, TEPCO and its research partners have been developing robots and remote visualization devices to search for melted fuel debris deep inside the Daiichi reactor units, and to help plan for its eventual removal. On January 30th, 2017, a long telescoping device with a camera and radiation measurement device attached was inserted through an existing opening in the reactor containment of Unit 2 for the first time, and successfully extended approximately 8 meters into in an area known as the “pedestal,” to measure and take images from immediately below the damaged reactor pressure vessel (RPV). In addition to finding the area covered with molten material likely to be fuel debris, radiation levels of 530 Sieverts per hour were detected, which would be fatal to a person exposed for only a few seconds.
It must be stressed that radiation in this area has not been measured before, and it was expected to be extremely high. While 530 Sv/hr is the highest measured so far at Fukushima Daiichi, it does not mean that levels there are rising, but that a previously unmeasurable high-radiation area has finally been measured. Similar remote investigations are being planned for Daiichi Units 1 and 3. We should not be surprised if even higher radiation levels are found there, but only actual measurements will tell. Unit 4 was defuelled at the time of the accident, and though the reactor building exploded and the spent fuel pool was dangerously exposed, it did not suffer a meltdown, so similar investigations are not being conducted.
Fake News Item #3: “Fukushima’s radiation is so bad it’s even killing robots.”
Five years after Fukushima, the exclusion zone is in better shape, but still a mess. The area around its once functional nuclear reactors are by far the most inhospitable. So much so that the radiation even managed to kill robots that had been sent in to help clean up.
Five robots that have gone into the reactor in order to help remove spent fuel rods have failed to return, reports Reuters. The issue? The radiation levels are so high that the robot’s internals just melt. We’ve seen this happen before.
Naohiro Masuda, Tepco’s head of decommissioning, explained the difficulties the company faces in an interview. Not only do the robots tend to fail due to the failure of their wiring, but it’s also not easy to get replacements. These aren’t just off-the-shelf bots; they have to be designed specifically for the challenges of the particular building they enter, and that takes about two years of design.
None of the robots have been “killed” by radiation…
Melted Nuclear Fuel Search Proceeds One Dead Robot at a Time
by Stephen Stapczynski and Emi Urabe
February 16, 2017
The latest robot seeking to find the 600 tons of nuclear fuel and debris that melted down six year ago in Japan’s wrecked Fukushima Dai-Ichi power plant met its end in less than a day.
The scorpion-shaped machine, built by Toshiba Corp., entered the No. 2 reactor core Thursday and stopped 3 meters (9.8 feet) short of a grate that would have provided a view of where fuel residue is suspected to have gathered. Two previous robots aborted similar missions after one got stuck in a gap and another was abandoned after finding no fuel in six days.
After spending most of the time since the 2011 disaster containing radiation and limiting ground water contamination, scientists still don’t have all the information they need for a cleanup that the Japanese government estimates will take four decades and cost 8 trillion yen ($70.6 billion). It’s not yet known if the fuel melted into or through the containment vessel’s concrete floor, and determining the fuel’s radioactivity and location is crucial to inventing the technology needed to remove it.
“The roadmap for removing the fuel is going to be long, 2020 and beyond,” Jacopo Buongiorno, a professor of nuclear science and engineering at the Massachusetts Institute of Technology, said in an e-mail. “The re-solidified fuel is likely stuck to the vessel wall and vessel internal structures. So the debris have to be cut, scooped, put into a sealed and shielded container and then extracted from the containment vessel. All done by robots.”
The machines are built with specially hardened parts and minimal electronic circuitry so that they can withstand radiation, if only for a few hours at a time. Thursday’s mission ended after the robot’s left roller-belt failed, according to Tokyo Electric, better known as Tepco. Even if it had returned, this robot, like all others so far designed to aid the search for the lost fuel, was expected to find its final resting place inside a reactor.
No. 2 Unit
On Thursday, Toshiba’s scorpion-like robot entered the reactor and stopped short of making it onto the containment vessel’s grate. While Tepco decided not to retrieve it, the company views the attempt as progress.
“We got a very good hint as to where the fuel could be from this entire expedition” Tepco official Yuichi Okamura said Thursday at a briefing in Tokyo. “I consider this a success, a big success.”
Tepco released images last month of a grate under the No. 2 reactor covered in black residue that may be the melted fuel — one of the strongest clues yet to its location. The company measured radiation levels of around 650 sieverts per hour through the sound-noise in the video, the highest so far recorded in the Fukushima complex.
The Hitachi and Toshiba robots are designed to handle 1,000 sieverts and no robot has yet been disabled due to radiation.
Because the No. 2 unit is the only one of the three reactors that didn’t experience a hydrogen explosion, there was no release into the atmosphere and radiation levels inside the core are higher compared to the other two units, according to the utility.
“The Hitachi and Toshiba robots are designed to handle 1,000 sieverts and no robot has yet been disabled due to radiation.”
Fake News Item #4 (or Urban Legend): TEPCO is dumping/pumping radioactive water into the ocean.
While I can’t locate an article from a reputable news outlet for this one, it has been a persistent urban legend. They are neither dumping nor pumping radioactive water into the Pacific. This image was circulated around the Internet with the claim that it depicted the flow of radioactive water across the Pacific Ocean…
The map was generated at the time of the earthquake and is of the projected height of the tsunami.
At no time has TEPCO intentionally pumped or dumped radioactive water into the ocean. Some contaminated water leaks into the ocean by infiltrating the local groundwater flow…
March 8, 2016, 9:24 AM
5 years on, Japan nuke plant still leaking radioactive water
TOKYO — After battling radioactive water leaks for five years at Japan’s crippled Fukushima Dai-Ichi nuclear plant, the utility that ran it says it will need another four to finish the job.
“We will bring an end to the problem by 2020,” says Yuichi Okamura, who led the Tokyo Electric Power Co. team dealing with water at Fukushima from the early days to last summer.
The contaminated water, now exceeding 760,000 tons and still growing, has been a major challenge that has distracted workers from decommissioning the plant. It is stored in more than 1,000 industrial tanks, covering much of the vast plant grounds.
Okamura says TEPCO expects that by 2020, it will have collected and treated all contaminated water pooled around the reactors, and will need to continue processing only the water necessary to cool the reactors.
TEPCO has managed to reduce the flow of contaminated water and hopes to get regulators’ approval within a month to activate an underground “ice wall” that would block out more water. The final step, though, remains contentious: Getting permission to release the water into the sea, after it has been treated to remove most radioactive elements.
The three damaged reactors still need to be cooled with water to keep their melted cores from overheating. The water picks up radiation and leaks out through cracks and other damage from the disaster. The water flows to the basements, where it mixes with groundwater, swelling the volume of contaminated water.
TEPCO has cut groundwater infiltration to 150 tons per day, nearly one-third of the amount two years ago, mainly by pumping out groundwater upstream and directing it to the ocean. The utility hopes the underground ice barrier will eliminate all groundwater inflow.
Radioactive water continues to leak into the ocean, but at a far lesser rate than it did early in the disaster. Ocean radiation levels are about a thousandth of what they were soon after the accident, according to Ken Buesseler, a radiochemist with Woods Hole Oceanographic Institution (WHOI) who has monitored the area. Because of concerns about the health of marine life, commercial fishing is still banned in waters just off the plant.
The only water they are directing into the ocean is uncontaminated groundwater and decontaminated waste water. By pumping out upstream groundwater, they have reduced the flow rate of contaminated water into the ocean.
From Woods Hole Oceanographic Institute…
What has been released from the Fukushima reactors and how dangerous is it?
Releases from the Fukushima reactors have included dozens of radioactive elements, but with regard to materials released into the ocean, most of the attention has been on three radioactive isotopes released in large amounts: iodine-131, cesium-137, and cesium-134. Iodine-131 decays quickly and any that was released from Fukushima is no longer detectable in the environment, but it was a significant health concern at the start of accident. Cesium-137 and -134 were released in the largest amounts. At the height of the accident, levels in the ocean near the docks at the reactors were 50 million times higher than before the accident and, at those levels, were a direct threat to marine life. Levels dropped quickly after the first month and today are many thousands of times lower, which is less of a direct health threat, but still an indication of ongoing leaks.
Are the continued sources of radiation from the nuclear power plants of concern?
The site of the Fukushima Daiichi nuclear power plant is an ongoing source of radionuclides (pdf) in to the ocean—something I’ve seen evidence of in my data and published since 2011. However, the rate of release has fallen significantly since March 2011. At current rates of release, it would take 5,000 years to equal the amount of cesium that entered the ocean in the first month of the accident. For the workers at the site, direct exposure from leaking storage tanks is of greater health concern because exposure from these concentrated sources is much higher. For the general public, it is not direct exposure, but uptake by the food web and consumption of contaminated fish that is the main health concern from the oceans.
While Fukushima is still decades away from full decommissioning, the situation is currently far better than it was nearly six years ago.
Fake News Item #5: The Fukushima nuclear disaster was due to a failure of nuclear technology.
This is perhaps the most egregious fake news item of all. The Fukushima disaster was the result of the loss of external and backup power sources, rendering the cooling systems inoperable…
Events at Fukushima Daiichi 1-3 & 4
It appears that no serious damage was done to the reactors by the earthquake, and the operating units 1-3 were automatically shut down in response to it, as designed. At the same time all six external power supply sources were lost due to earthquake damage, so the emergency diesel generators located in the basements of the turbine buildings started up. Initially cooling would have been maintained through the main steam circuit bypassing the turbine and going through the condensers.
Then 41 minutes later, at 3:42 pm, the first tsunami wave hit, followed by a second 8 minutes later. These submerged and damaged the seawater pumps for both the main condenser circuits and the auxiliary cooling circuits, notably the Residual Heat Removal (RHR) cooling system. They also drowned the diesel generators and inundated the electrical switchgear and batteries, all located in the basements of the turbine buildings (the one surviving air-cooled generator was serving units 5 & 6). So there was a station blackout, and the reactors were isolated from their ultimate heat sink. The tsunamis also damaged and obstructed roads, making outside access difficult.
All this put those reactors 1-3 in a dire situation and led the authorities to order, and subsequently extend, an evacuation while engineers worked to restore power and cooling. The 125-volt DC back-up batteries for units 1 & 2 were flooded and failed, leaving them without instrumentation, control or lighting. Unit 3 had battery power for about 30 hours.
At 7.03 pm Friday 11 March a Nuclear Emergency was declared, and at 8.50pm the Fukushima Prefecture issued an evacuation order for people within 2 km of the plant. At 9.23 pm the Prime Minister extended this to 3 km, and at 5.44 am on 12th he extended it to 10 km. He visited the plant soon after. On Saturday 12th he extended the evacuation zone to 20 km.
Yes, the reactors were old (1960’s) technology… But it wasn’t the nuclear technology which triggered the disaster. It was a failure to anticipate anything more than a 3.1 meter tsunami.