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Japan Nuclear Watch, Friday: Where Did the Water Radiation Come From at Unit 3?

5:44 am in Uncategorized by Scarecrow

Reactor Containment & Fuel Storage from UCS; (h/t commenter lobster)

It’s 9:30 a.m. EDT, which is 10:30 p.m. on Friday evening in Japan. [Updates below.]

[Update II, 11:00 a.m. EDT]: Kyodo News reports workers have begun to inject fresh water into the reactors at Units 1 and 3 (Unit 2 is next) to help flush sea water and salt buildup out of the reactor and cooling water systems. That’s a good step, because salt buildup can lock the valves and inhibit water flows within the reactor. (They’re still spraying sea water into the spent fuel storage pools.) They’re also finding more radioactive water leaks and standing water in other units. ]

Concerns on Friday focused on (1) the continuing spread of radiation in Fukushima and surrounding prefectures, with local citizens anxious to evacuate areas beyond the mandated 20 kilometer radius and (2) the inability of the government either to gain control of the crippled Fukushima Daiichi reactors or to explain the exact source and nature of the continuing radiation leaks.

The latter concern increased yesterday when authorities reported that three workers suffered radiation exposure while standing in water, trying to lay cables to connect an outside electrical power cable to Unit 3. (Power cables are already connected at Units 1 and 2; see previous updates.)

Two of those workers had to be hospitalized for possible radiation burns on their feet. [A late medical report claims that two of the three exposed workers do not appear to have skin damage but have suffered from "internal exposure."] Initial reports jumped at the claim that the workers had walked through puddled water (with no protective boots) outside the reactor building and that the exposure levels were “10,000 times normal exposure levels.”

Since normal levels are extremely small, the “10,000 times normal” figure was not the only point. Rather, the concern quickly shifted to where the exposure occurred, where the water was coming from and how it became contaminated. I originally thought the source might be runoff from the sea water spraying, but that assumed the water was outside. It was inside.

It now appears the workers were inside a part of the turbine/generator building, which is separate from but connected to the reactor building. The connections with the reactor include a series of pipes that carry pressurized steam from the reactor to the turbines, which then drives the generators to produce electricity. Other pipes then carry the cooler condensed water back to the reactor. There are various valves along the way.

[Update I]: as the NYT reports, there are pipes from the reactor carrying away corrosive materials from the reactor to a filtering system inside the turbine-generator building.

But Michael Friedlander, a former nuclear power plant operator for 13 years in the United States, said that the presence of radioactive cobalt and molybdenum in water samples taken from the basement of the turbine building of reactor No. 3 raised the possibility of a very different leak.

Both materials typically occur not because of fission but because of routine corrosion in a reactor and its associated piping over the course of many years of use, he said.

These materials are continuously removed from the reactor’s water system as it circulates through a piece of equipment called a condensate polisher, which is located outside the reactor vessel. The discovery of both materials in the basement suggests damage to that equipment or its associated piping, as opposed to a breach of the reactor vessel itself, Mr. Friedlander said.]

Did the excess irradiated water on the floor of the turbine/generator building come from leaks in these pipes or valves coming from/returning to the reactor building? That would indicate the source of the irradiated water was inside the reactor itself, not the spent fuel storage pool. And the type of irradiation would be another sign, if they needed one, of likely breakdown, possibly continuing, of fuel inside the reactor core [or corrosion in the reactor]. But as of Friday night, they apparently had not found the “leak” inside the turbine/generator building, so they’re haven’t confirmed this scenario.

Regarding the other units, a Defense Forces helicopter made an overhead video of the four reactor buildings. It’s shown periodically on the NHK TV feed and gives a better perspective on the damage to each reactor.

At Unit 1, where a hydrogn explosion a week ago destroyed the upper walls and roof of the reactor, we can now see that the roof was not blown off; it collapsed down, effectively covering the reactor components and spent fuel storage pool below. Commentators explaining the video did not know how much that complicates the ability to spray water into the storage pool from above, so it’s not clear how they’re maintaining cooling water levels in the storage pool.

At Unit 2, the earlier hydrogen explosion caused minimal damage to the exterior of the reactor building, but it is suspected of causing damage at least to the pressure suppression pool at the bottom of the reactor. In an emergency, if pressure builds up inside the reactor, it can inject steam into the suppression pools to relieve the pressure and cool the reactor down, while cooler water is, one hopes, injected back in. We so much damage from the top, we can’t see that lower structure in this video. The emergency crews punched out two holes in the building exterior, one in the upper levels on one side, another in the roof. They did this to allow venting of steam to prevent another hydrogen explosion, and you can see steam escaping from both holes.

At Units 3 and 4, explosions at each caused massive damage to the external building and likely serious damage to some components inside. For example, among the twisted steel rubble at Unit 4, you can make out a green structure that might have been the massive crane that operates above the reactor vessel and that is used for moving fuel rods in and out of the building and between the reactor vessel and the spent fuel storage pool. If that fallen structure we see is the crane, the question is, what did it damage on the way down? It’s usually above the reactor vessel, the containment structure, the spent fuel storage fuel and lots of critical coolding/steam pipes and valves, etc.

The inability of authorities to get these events under control, and continuing reports of worker exposure, unsafe tap water and produce is naturally increasing the alarm among residents. TV interviews are showing more and more folks saying they want to leave, just get out, but not getting answers they believe from the Japanese Government. Government officials are now saying it’s okay for folks within the 30 kilometer radius to leave voluntarily, but as of Friday, they hadn’t ordered that evacuation. Instead, the Times reports they are quietly encouraging folks to move away. And it’s all complicated by the fact the quakes and tsunami left tens of thousands homeless and requiring massive relief efforts on water, food, shelter medical care.

They need a break, some good news, if the gods are listening.

Helpful Sources:

NHK live tv feed

Union of Concerned Scientists

Kyodo News: Japan Nuclear Crisis

Picture of Unit 1 control room, via Kyodo News

Nuclear Power Plant Primer — good expert video

You can also find Unit by Unit status updates (pdf) at the IAEA site

Japan’s Flawed Nuclear Power Regulation: It’s Our Story Too

9:27 am in Uncategorized by Scarecrow

The New York Times today has an interesting article about how Japanese nuclear plant regulators only a month before the quake extended the operating license for the destroyed Unit 1 reactor at Fukushima Daiichi Nuclear Station. The plant had been in operation since 1971, but it passed the safety review for extending another 10 years, even though its safety systems were clearly outmoded and whistleblowers showed the utility, TEPCO, had repeatedly lied and covered up safety problems at its reactors.

Nothing about that story surprised me. What caught my attention was the Times’ suggestion the US regulatory regime is better. According to the story, Japanese safety regulation suffered from conflicts of interest, since the agency responsible for oversight was also charged with promoting the technology and assuring the public. The US is different, the Times story implies: [my bold]

Like many critics of Japan’s nuclear industry, Mr. Sato attributed weak oversight to a conflict of interest that he said essentially stripped the Nuclear and Industrial Safety Agency of its effectiveness. The agency, which is supposed to act as a watchdog, is under the Ministry of Economy, Trade and Industry, which has a general policy of encouraging the development of Japan’s nuclear industry.

The ministry and the agency, in turn, share cozy ties with Tokyo Electric and other operators — some of which offer lucrative jobs to former ministry officials in a practice known as “amakudari,” or descent from heaven. . . .

The Japan Nuclear Energy Safety Organization, which is supposed to provide a second layer of scrutiny, is understaffed and largely an advisory group. Masatoshi Toyoda, a former vice president at Tokyo Electric who, among other jobs, ran the company’s nuclear safety division, said the organization should be strengthened. The United States had a similar setup until the 1970s, when Congress broke up the old Atomic Energy Commission into the Department of Energy and the Nuclear Regulatory Commission.

So what was the problem? They had a government responsible for oversight but also advocating the technology and assuring the public it’s safe. They had a revolving door between the industry and government, with lucrative careers for those moving from oversight to industry. They suffered from insufficient oversight staff and funding and regulatory capture.

Which of these elements is missing from the US scheme? None. In fact, it’s just as bad or worse here.

We’ve had successive Democratic and Republican Administrations being major advocates of nuclear power and its safety. Our President routinely assures us how safe the technology is even as we watch plants explode and melt down. You can bet neither this nor previous Presidents appointed NRC Commissioners with strongly negative views of nuclear plant safety, because strong industry skeptics can’t get confirmed. See Krugman today for other examples.

Worse, we have a Tea-GOP Congress that thinks the problem with America is too much regulation, and a bunch of anti-science crazies slashing budgets and repealing regulatory authority for every agency with oversight over the energy industry. We’ve got million dollar revolving doors.

I’ve worked with many highly qualified and dedicated engineers and technical experts in my career, and I have the utmost respect for their integrity. Most do the best they can within the contraints they’re given. But the people who manage them and the people who pay their salaries, and more important, the Wall Street investors they listen to are a different breed. The more their compensation depends on taking shortcuts and concealing problems, the more likely they’re inclined to do so. Inevitably, the entire system gets corrupted from the top down, from bought legislators to captured Presidential advisers and regulatory agency appointees and the people they pick to manage oversight.

Of course it’s not just nuclear. Consider what we’ve witnessed with the Massey coal mine disasters, or the BP Gulf oil disaster, or Chevron in South American, or Koch Industries or the Chamber of Commerce and Exxon Mobil’s onslaught on climate science, or natural gas fracking in Pennsylvania . . . . Regulatory capture, promotion mixed with oversight, revolving doors and corrupt appointees. The same patterns show up everywhere, without exception.

Good engineering and safety analysis eventually get ignored or compromised. Whistleblowers are stifled and lose their jobs without protection. Safety reports get buried. Regulators become captured as the political system’s corruption takes its toll.

I’ve long since concluded that choices about risky technnologies aren’t primarily a question whether inherently unsafe technologies like nuclear power can, in theory, be made relatively “safe enough.” In another world, perhaps they could be. No, the problem is the money and what it does to the politics, and that’s what determines whether a technology is “safe.”

It’s usually the politics that produce the disasters. As long as that’s true, we’re safer with technologies that don’t lead to horrendous catastrophes even if the political system fails, as it always does.

Japan Nuclear Watch: Press Conf. on Unit 2 Explosion and Unit 4 Fire

6:40 pm in Uncategorized by Scarecrow

Breaking: There are [now confirmed] reports of yet another explosion at Unit 4, presumably associated with the fire.
________

Japan’s Prime Minister gave a press conference at 11:00 a.m. (Tokyo) Tuesday and an official overseeing the nuclear emergencies answered questions about the status of the four units at Fukushima Nuclear Station.

The briefing part revealed there has been an explosion and fire at Unit 4 which, as of the presser, they were still trying to control. [Later reports say it's [now] extinguished.

Unit 4 had not been operating when the quakes hit last week and was supposedly in safe cold shutdown. However, cooling at that reactor is still required for the spent fuel pools, and its absence is a problem that can allow heat buildup from residual radioactive decay. The damage associated with this fire caused a significant radiation leak and apparently an explosion.

Officials suggested that this source, and not solely or necessarily the explosion at Unit 2, may be the source of highly elevated radiation readings at the Station. Because of increased levels, the government evacuated about 800 non-essential personnel from the Fukushima Daiichi Station, leaving only 50 workers to continue with sea water injections at all units.

The Government also directed that the public evacuation radius be set at 20 kilometers, and that between 20 and 30 km, residents remain indoors. Later reports note detecting higher levels of radiation in Tokyo and other cities.

The official emphasized the very high levels of radiation near Unit 4, with the measurement units being expressed in mili-sievert levels instead of micro-sievert levels. Whereas before we had as high as 8,217 micro-sievert/hour, the new readings were more like 300-400 mili-sieverts/hour near Unit 4. The official noted this level is clearly dangerous to humans.

The official said that as of 6:00 a.m. Tuesday, all but 50 workers involved in water injections have been evacuated. Sea water injections are still bein attempted at Units 1, 2, and 3. [earlier reports suggested they only had the fire equipment to deal with one plant at a time.]

Following is a paraphrase of the Q and A with the official overseeing nuclear issues:
Q. How are you sure the pressure vessel has not been damaged?
A. Water injection has been maintained. And pressure has been stabilized; we have to continue those efforts.
Q. How serious is fire at Unit 4?
A. I mentioned it first because it occurred earlier.
Q. Is there damage to part of the containment vessel?
A. There is a high probability that it was. [May be a mistranslation of terms here]
Q. Radiation levels a threat to the public?
A. Very little possibility of harm to public
Q. Status of fire at Unit 4?
A. Still working to extinguish the fire at Unit 4.
Q. Evacuation radius?
A. Out to 20 km = evacuate. Considering out to 30 km; but for now, just stay indoors.
Q. Radiation readings related to damage to Unit 2?
A. Explosion at #4 reactor could have caused that [after explosion?]
Q. What if fire continues?
A. We’re making every effort to put it out. The spent fuel is not going to “catch fire” in general sense, but its heat likely caused the fire. Fire is in building area; but it’s best to extinguish to keep temps down and prevent release of radiation.
Q. Further release from other units?
A. Possible some could have been released. Ask TEPCO. But current high readings are from this fire/explosion at Unit 4, not from the Unit 2.
Q. What is your advice?
A. [Repeats evac and remain indoors] Minimal amounts may spread further, but further away the level is lower, so stay calm.
In another Onadaga plant, the levels will not cause damage to health.
A. For people between 20-30 km range, there are towns that overlap/in beetween. He calls them out. [About 8-10 towns]
Q. Sec. Gen. of IAEA says you asked for experts?
A. Not aware of any Japanese request to IAEA, but after quake, we’ve asked for support from various countries.
Q. Neutron radiation?
A. That was from Unit 3, because of its nature [fuel type]
Q. How long to extinguish Unit 4 fire, given you think it’s source of radiaion?
A. Working on it.
Q. Are you ontinuing to inject water at all units?
A. Yes. Thank you for your questions.


Live Streaming by Ustream.TV

Japan Nuclear Watch: Third Explosion, Possible Cracked Containment at Unit 2

3:17 pm in Uncategorized by Scarecrow

This cutaway diagram shows the central reactor vessel and thick concrete containment in a typical boiling water reactor of the same era as Fukushima Daiichi 1 (image: www.world-nuclear-news.org)

Japanese authorities now reporting that about 6:14 a.m. (Tokyo) Tuesday, March 15, there was an explosion at the Daiichi Unit 2 of the Fukushima Nuclear Station. This explosion was heard, not seen from the outside. The explosion reportedly did not blow off the roof/walls, as the explosions did at Units 1 and 3.

The explosion reportedly occurred near the containment area. Plant officials fear there may now be a crack in the reactor containment, which would allow more serious releases of radiation. A “pressure suppression pool,” the doughnut-shaped area at the bottom of the reactor vessel may have been damaged, which officials are describing as “serious.”

They are evacuating non-essential personnel in/around the plant after initial outside readings reached 965 micro-Sievers/hour. Radiation levels spiked to 8,217 micro-SV/hour, before dropping. That’s “more than eight times the 1,000 micro sievert level to which people are usually exposed in one year.” Winds are reported from the NNW.

At the time of the explosion, about one half of the reactor core — about 2.7 meters — had become uncovered. According to one analyst, at some point, the entire core was exposed. Pressure reached 3 atmospheres, but has fallen back to 1.

These pressure and radiation readings suggest the reactor pressure vessel holding the core may have been breached.

There is also an inoperable value that would otherwise allow pressure releases. That’s preventing or limiting the ability to inject cooling water.

An official is describing the event on this live tv feed, with English translation.

In a follow up news conference by TEPCO . . . utility officials said they’re continuing to inject sea water, with only a few essential personnel. They’re apologizing to the public. Reporters keep asking for details of the incident, and the officials keep apologizing!

Reporter: “we’re not asking for your feelings! Tell us the facts.”

Response: “The blast was heard; we checked parameters; pressure readings indicated some damage to the pressure pool. That caused the evacuation of the operators. Being carried out for the first time.”

“Water level was at minus 2700 mm [?} before and after; we're trying to decide what that means."

Q. What caused the damage to the suppression pool?
A. We have only confirmed the pressure went down. The Cabinet official assumed there was damage.
[Reporters obviously frustrated]
Q. Can anyone explain this? Have Unit 1 and 3 been evacuated?
A. Only those necessary are there.

Update from 11:00 a.m. (Tokyo) presser from Cabinet Official:

As of 6:00 a.m. Tuesday, all but 50 involved in water injections have been evacuated. Injections are occurring at Units 1, 2, and 3. There was a fire earlier at Unit 4, which was in cold shutdown when the quake occurred.)

Evacuations directed around 30 km radius. Everyone else urged to remain indoors.

Cabinet meetings continuing.

[note: these are paraphrases of Q and A]
Q. How are you sure the pressure vessel not been damaged?
A. Water injection has been maintained. And pressure has been stabilized; we have to continue those efforts.
Q. How serious is fire at Unit 4?
A. I mentioned it first because it occurred earlier.
Q. Is there damage to container vessel?
A. Report there is a high probability that it was.
Q. Radiation levels?
A. Very little possiblity of harm to public
Q. Status of fire at Unit 4?
A. Still working to extinguish the fire at Unit 4.
Q. Evacuation radius?
A. Out to 20 km = evacuate. Considering out to 30 km; but for now, just stay indoors.
Q. Radiation readings related to damage to Unit 2
A. Explosion at #4 reactor could have caused that [explosion?]
Q. What if fire continues?
A. We’re making every effort to put it out. The spent fire is not going to “catch fire” in general sense. Fire is in building area; but it’s best to extinguish to keep temps down and prevent release or radiation.
Q. Release possible.
A. Possible some could have been released. Ask TEPCO. But current high readings are from this fire, not from the Unit 2.
Q. What is your advice?
A. [Repeats evac and remain indoors] Minimal amounts may spread further, but further away the level if lower, so stay calm.
In another Onadaga plant, the levels will not cause damage to health.
A. For people between 20-30 km range, there are towns that overlap/inbeetween. He calls them out. [About 8 towns]
Q. Sec. Gen of IAEA says you asked for experts?
A. Not aware of any Japanese request t IAEA, but after quake, we’ve asked for support from various countries.
Q. Neutron radiation?
A. That was from Unit 3, because of its nature [fuel type]
Q. How long to extinguish Unit 4 fire, given you think it’s source of radiation?
A. Working on it.
Q. Continue to inject water?
A. Yes. Thank you for your questions.


Live Streaming by Ustream.TV

Japan Nuclear Watch, Wed. am JST: New Fire and Explosion at Unit 4 Fuel Pond

4:56 am in Uncategorized by Scarecrow

This cutaway diagram shows the central reactor vessel and thick concrete containment in a typical boiling water reactor of the same era as Fukushima Daiichi 1 (image: www.world-nuclear-news.org)


Japanese responders continue to battle rising heat and pressure and falling water levels in the damaged reactors, Units 1 and 3, at Fukushima I (Daiichi) Nuclear Power Station.

But the big news is that Unit 2 lost cooling and the core was left uncovered, allowing a likely partial meltdown. There has not yet been an explosion at Unit 2, and they’re trying to relieve pressure to prevent that. More on that below.

And there is concern about the condition of spent fuel rods in pools located above the reactor. They too must be continuously cooled, but the cooling systems are also disabled.

The New York Times interviewed US industry and regulatory officials who had been briefed on the Japanese efforts and reports several interesting facts mentioned in FDL threads here but not previously summarized. Also note the photo at the top of the Times’ article, showing the damage to the Unit 3 reactor building from yesterday’s explosion.

– In addition to the reactors themselves, they’re worried about the condition of the spent fuel holding ponds, which are inside the reactor buildings. The spent fuel has ceased fission reactions, but residual radioactive decay continues and must be continuously cooled.

. . . there was deep concern that spent nuclear fuel that was kept in a “cooling pond” inside one of the plants had been exposed and begun letting off potentially deadly gamma radiation.

– The reason they not only lost the back-up generators when the tsunami hit, but can’t easily replace them with portable generators brought to the site is because the connection points, with the generators, were completely flooded by the tsunami.

[The tsunami] easily overcame the sea walls surrounding the Fukushima plant. It swamped the diesel generators, which were placed in a low-lying area, apparently because of misplaced confidence that the sea walls would protect them.

– The core in Daiichi Unit 1 suffered significant exposure when water levels fell:

While estimates vary, several officials and industry experts said Sunday that the top four to nine feet of the nuclear fuel in the core and control rods appear to have been exposed to the air — a condition that that can quickly lead to melting, and ultimately to full meltdown.

– Official reports of pressure readings inside the reactors are, as we’ve suspected, not necessarily reliable.

Workers inside the reactors saw that levels of coolant water were dropping. They did not know how severely. “The gauges that measure the water level don’t appear to be giving accurate readings,” one American official said.

– With all the normal/backup water cooling systems inoperable, the responders where attempting to inject sea water using fire-fighting equipment, but with limited success.

To pump in the water, the Japanese have apparently tried used firefighting equipment — hardly the usual procedure. But forcing the seawater inside the containment vessel has been difficult because the pressure in the vessel has become so great. . . . it was “not clear how much water they are getting in, or whether they are covering the cores.”

– The outer structure of the Daiichi units was reportedly designed to be blown away in an explosion, to relieve pressure but preserve the reactor vessel and containment structure inside.

The walls of the outer building blew apart, as they are designed to do, rather than allow a buildup of pressure that could damage the reactor vessel.

We’ll be updating as needed.

Update I: (h/t lobster) Last night (our time) the core at Unit 2 became uncovered when sea water cooling efforts failed for a time, so we’ve got another meltdown in the works:

Kyodo (22:15) reporting Unit 2 fuel rods were fully exposed for about 2.5 hours.

This would be Fukushima Daiichi Unit 2, where the fuel rods were completely exposed for a time when the fire equipment pumping sea water into the reactor ran out of fuel. (h/t lobster)

Fuel rods at the quake-hit Fukushima No. 1 nuclear power plant’s No. 2 reactor were fully exposed at one point after its cooling functions failed, the plant operator said Monday, indicating the critical situation of the reactor’s core beginning to melt due to overheating. . . .

The seawater injection operation started at 4:34 p.m., but water levels in the No. 2 reactor have since fallen sharply with only one out of five fire pumps working. The other four were feared to have been damaged by a blast that occurred in the morning at the nearby No. 3 reactor.

The utility firm said a hydrogen explosion at the nearby No. 3 reactor that occurred Monday morning may have caused a glitch in the cooling system of the No. 2 reactor.

. . . To prevent a possible hydrogen explosion at the No. 2 reactor, TEPCO said it will look into opening a hole in the wall of the building that houses the reactor to release hydrogen.

Apparently they only have one operable fire pump available to pump sea water at Daiichi, so they’re focused now on Unit 2, even though Units 1 and 2 also need sea water.

Update 2, 12:00 p.m. EDT: Reports now indicate that despite efforts to inject sea water into Unit 2′s reactor, the core became exposed again. Officials are now conceding that partial meltdowns of exposed fuel are likely occurring at all three units at Fukushima Daiichi.