Wednesday, March 23, 2011
Black smoke again from reactor unit #3 in Fukushima on Wednesday afternoon, and workers pulled back for a time.
The warnings on feeding tap water to infants issued on Wednesday for Tokyo a metropolitan area with 35 million or more residents seem to have brought out a new round of placating and typically garbled messages from mainstream media on radiation units and relative exposures.
Fortunately, most of the continuing radiation releases from the Fukushima plant are still being blown out to sea. That may change with the weather pattern on Friday. (ZAMG, Google English)
It is hard for ArchitectureWeek to grasp what seems to be so darn hard for mainstream media about telling a story straight down the middle, searching out the emerging facts and communicating those facts promptly, clearly, and accurately. Not playing on fears, either upward or downward.
Tuesday, March 22, 2011
A long snorkel concrete pump truck was used successfully, for three hours late on Tuesday, to pump water into the fuel storage pool at reactor #4 (NHK).
External electric power is now connected to the six reactor buildings at the Fukushima Daiichi nuclear power plant, according to TEPCO.
"Japan's science ministry says radiation exceeding 400 times the normal level was detected in soil about 40 kilometers (25 miles) from the troubled Fukushima Daiichi nuclear power plant." (NHK)
Austria's weather service, the Central Institute for Meteorology and Geodynamics in Vienna, has released new "order of magnitude" estimates of the amounts of radioactive material released (English) during the first four days of the compound accident at the Fukushima Daiichi nuclear power plant.
Developed by cross-referencing point samples with weather modeling, these early estimates suggest iodine-131 releases comparable to 20% of the total amount released in the Chernobyl accident, and cesium-137 releases comparable to 50% of the total amount released in the Chernobyl accident.
Emphasized with bold in the original, "these figures are an order of magnitude estimate for the first four days of the accident."
Monday, March 21, 2011
Smoke was observed coming from reactor units #2 and #3 during the day Monday in Japan. Leaks of radioactive material are continuing (NHK).
About 100,000 nuclear accident evacuees are currently reported as sheltering at 220 evacuation centers outside the 20-kilometer (12-mile) official evacuation area.
The Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT) has started posting regular charts of measured radiation levels.
Reported measurements of agricultural-product and tap-water contamination outside the official evacuation area in Japan are causing concern. Although the levels of contamination detected to date are small, the range of spread is an issue.
The Japanese government "has asked 4 prefectures Fukushima, Ibaraki, Tochigi and Gunma to stop shipping spinach and another leafy vegetable, Kakina, as the items may contain excess amounts of radioactive materials." (NHK)
With releases of radioactive material continuing, it is hard to escape the sense that local contamination levels so far represent a temporary minimum level of impact so far, while the ultimate level of impact remains distressingly undefined.
Sunday, March 20, 2011
Austria's weather service, the Central Institute for Meteorology and Geodynamics in Vienna, has modeled the plume of radioactive material reaching out over the Pacific Ocean, with maps online here (click on graphics). As Nature explains in their blog coverage of the bulletin from Austria, red color on the maps represents 100 millisieverts per hour (100 mSv/hr).
As the maps illustrate, the winds, continuing to blow offshore, have been a huge factor in reducing the spread of radioactive material over Japan.
Nature, the preeminent international scientific journal, is maintaining a special coverage page on the Japan earthquake and nuclear crisis, and a Nature science blog is posting updates on the nuclear crisis. These tend to be rather more accurate than much of the mainstream media coverage.
The Nature blog points out that "The television and various news sources are clogged with radiation numbers and experts trying to explain them. Unfortunately the result seems to be a confusing tangle of data that is difficult to understand.
"The most fundamental problem seems to be the rampant switching from micro to millisieverts."
Nature also discusses how data from a major network monitoring the spread of radioactivity is largely kept confidential by the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO), in their news article Radiation Data from Japanese Disaster Starts to Filter Out.
Reports have been that there is some progress cooling damaged reactors and spent fuel pools, and toward connecting up an outside electric supply to help re-establish regular cooling. Details on that work, and on releases of radioactive material from the plant which are likely to be continuing at some level remain sketchy.
Saturday, March 19, 2011
Accident conditions at the damaged reactors and fuel storage pools in Fukushima continue to be extremely serious.
Confusion continues between reports using millisieverts (mSv) and reports using microsieverts (μSv), even across official and respected sources. Errors may occur in notation, translation, transcription, announcing, and/or attending, which can then be propagated across news channels.
Radiation has been measured on food products including milk and spinach grown at distances 19 miles and even father from the Fukushima nuclear plant, indicating some contamination with radioactive materials.
Mapping of radiation hotspots in a wide area in Japan around the accident site show insufficient sampling, both in spacing and in frequency, to reasonably establish the overall distribution pattern of radioactive particles released from the plant. (See NY Times). Radiation levels reported at 170 μSv/hr (microsieverts per hour, on Thursday, 3/17) and 150 μSv/hr (on Friday, 3/18) at 30 kilometers (19 miles) from the plant is troubling, however.
The first slightly measurable indication of the plume of radioactive materials has been sensed at the west coast of the United States This indicates the normal movement of winds across the Pacific Ocean, rather than any significant immediate risk of radiation exposure in the U.S. It also represents the earliest stages of the nuclear accidents at Fukushima, before releases may have escalated somewhat.
New Official Information Summary
The Japan Atomic Industrial Forum (JAIF) has released a very informative summary information package including a chart with the detailed status of each reactor unit at each Fukushima nuclear power station, a timeline of events, maps, and more. While this package does not reveal new information, it does pull many bits of information together into just a few a clear, compact pages.
Pace of Spraying and Worker Exposure
Media have raised questions about why the water spraying operation is proceeding so slowly, even with the recent addition of a pumper truck to provide seawater. Long delays between episodes of spraying are observed, with equipment apparently sitting idle most of the time.
ArchitectureWeek speculates that the time delays may be driven, at least in part, by the critical issue of dose limitations for nuclear workers.
At a radiation level of 300 mSv/hr (millisieverts per hour), as appears to have been reported, and the annual dose limit per worker per year of 250 mSv (raised during this emergency from the existing Japanese limit of 100 mSv already twice the limit for a U.S. nuclear plant worker with a proportional increase in cancer risk for each exposed worker), each worker could be near the plant for less than an hour before accumulating a full year dosage.
Typically, even in an emergency, plant workers are sent home for the rest of the year, once they have reached a full year dose.
In the case of the current water-spraying efforts, this could mean that each new round of spraying requires a new crew of workers, trained up to operate the specialized fire-fighting equipment. At the end of the round of spraying, in less than an hour of time near the plant, it is likely that the whole crew of workers is ready to be sent home or at least limited to further work in low-exposure locations, farther away from the plant.
Friday, March 18, at the Fukushima Daiichi Nuclear Power Plant appears to have been much like Thursday, with a lot more water sprayed, and not a lot more information about the radiological developments.
The power cable, reportedly in place to provide reliable electric power from offsite to reactor #2, is apparently not yet energized. It remains unclear whether the cable can be usefully connected until the radiation levels around the reactors come down significantly and whether cooling pumps will still be operational, once re-powered.
Also on Friday, Japan's nuclear safety agency, the Nuclear and Industrial Safety Agency, upgraded the Fukushima Daiichi to INES Level 5. Other authorities suggest this compound incident may be on its way to, or already deserve, a level 6 designation.
Continuing Risk Factors
With cooling problems continuing at reactor cores and fuel storage pools, risks continue.
Tokyo Electric Power Company (TEPCO) has admitted that there is a possibility of "recriticality," in which fission would accelerate if fuel rods melted and the fuel materials happen to slump or flow together into a critical mass. (NY Times)
Short of the risk of accidental formation of a critical mass with increased self-heating, there appears to be a continuing risk of fuel rod burning that could distribute radioactive material into the atmosphere. Smoke was reported rising from one of the Fukushima reactor units again at 11:00AM Tokyo time (02:00AM UTC) on Thursday, and at times since.
Japanese authorities informed the IAEA that engineers were able to lay an external grid power line cable to reactor unit 2. That operation was completed at 08:30 UTC on Friday. The stated plan is to reconnect power to unit 2 once the spraying of water on the unit 3 reactor building is completed.
TEPCO announced around midnight Thursday that spraying water onto reactor unit #3 (commencing at 7:30pm Thursday evening with five defense force fire-fighting trucks) was measurably successful, with radiation measured at the plant gate dropping by a few percent to 292 mSv/h (millisieverts per hour) and then later to 283 mSv/h. TEPCO said it would like to spray water again on Friday morning.
The New York Times has reported on the significant background issue of on-site storage of large amounts of spent reactor fuel in the both Japan and the U.S., which has continued to increase in the absence of robust long-term storage solutions. "When the water in a storage pool disappears, residual heat in the fuel rods' uranium left over from their time in a nuclear reactor continues to heat the rods' zirconium cladding. This causes the zirconium to oxidize, or rust, and even catch fire." (NY Times)
During the day Thursday in Japan, efforts to provide water to overheating cooling pools at the Fukushima Daiichi plant were ineffective, both by helicopter and water cannon, while radiation levels around the plant remained very high, preventing direct access to the reactor buildings.
We know there is MOX fuel in the #3 reactor. Is there also MOX fuel, which includes plutonium, in one or more of the spent fuel cooling ponds? According to the IAEA, "spent MOX fuel... has a higher decay heat and radiation level."
On Thursday morning Tokyo time, water was reported to be boiling (very overheated) at spent fuel storage pools at reactors 3 and 4. "Reactor 4's pool may even be dry." (BBC) And according to the IAEA, spent fuel storage pools have been overheating at all of the offline reactors 4, 5, and 6.
It has been reported that a spent fuel cooling pond has become dry of water, which would directly cause a large increase in local radiation at the nuclear plant.
With the statement by U.S. energy secretary Steven Chu to Congress that the nuclear plant situation in Fukushima is now probably worse than the Three Mile Island accident, the Fukushima compound accident now clearly sits in a unique category among commercial nuclear breakdowns of the last generation beyond Three Mile island, not as bad as Chernobyl. At least, not as bad as Chernobyl, yet. The Fukushima situation is substantially out of control, and still getting worse.
The remaining 40-60 staff at the Fukushima Daiichi nuclear power plant were evacuated for some time on Wednesday due to high radiation levels, leaving the plant temporarily abandoned. About 750 workers had been pulled out previously.
Attempts to dump water on overheated plant areas by heavy helicopter were canceled due to high radiation levels for the aircraft.
Light-colored smoke issued from the area of Fukushima Daiichi reactor #3, and radiation levels have been fluctuating substantially.
Japanese authorities announced a second fire at the Unit 4 reactor of the Fukushima Daiichi nuclear power plant, cooling problems with the spent fuel storage pond, and release of radioactive material directly into the atmosphere. Then the second fire at #4 was unconfirmed. Delivering water to the storage pond is complicated by radiation levels too high to allow close approach (NHK, BBC, IAEA)
Radiation releases have been increasing and weather conditions are becoming less forgiving. Public health impacts of the ongoing nuclear disaster are becoming more significant, and the evacuation area around the plants has been expanded.
Donations statement for the Japanese Red Cross Society.
This article focuses on the major compound nuclear accident that has accompanied the natural disaster, with a complex engineering and public health situation that is still unfolding rapidly.
No organization in the history of nuclear power has had to fight three out-of-control reactors at the same time.
And in Fukushima right now, there's actually more, with the addition of cooling breakdown and fire at the spent fuel storage pools of the offline reactor #4.
An extremely dangerous level of cooling problems is now reported for all three reactors, about 220 kilometers (135 miles) north of Tokyo. At reactor #2, Tokyo Electric Power Company (TEPCO) has said the inner containment vessel (or the connected coolant toroid) may have ruptured.
And on Tuesday afternoon Tokyo time, a fourth reactor unit, offline but storing spent fuel in cooling pools, reportedly caught fire, with additional release of radioactive material.
On Wednesday, the Kyodo news agency reported from the Tokyo Electric Power Company that an estimated 70% of the nuclear fuel rods inside reactor 1 at Fukushima Daiichi have been damaged, along with 33% of the rods inside reactor 2. The basis for these estimates is not clear.
Above-normal releases of radiation and radioactive material are now continuing from all three permanently damaged reactors #1, #2, and #3 at Fukushima Daiichi. With containment buildings gone around two of the three badly damaged reactors, fuel cores damaged, and emergency cooling continuing with a "boil off" method, essentially unpreventable radioactive releases are likely to continue for weeks.