by Nelle Maxey
Update #1 – May 17, 2011
Since all the very bad news on Friday, things have continued to deteriorate at Fukushima. TEPCO continues to be unable to really respond to the increasingly critical situation. Lots of "plans", but in fact all the action is going to the ongoing flooding with cooling water which isn't working. (I've only selected the most important of many weekend stories).
• Now the fuel in No 1 reactor is being reported as possibly on the basemat or even outside the concrete containment vessel. (Remember my graphic from Friday where I showed two possible locations of the melted fuel.) There is some confusion in the press about this information. "Basemat" is reported as "basement" in some articles and the concrete, primary containment vessel (CV) is being confused with the concrete reactor building (which was the secondary level of "containment" prior to the explosions that blew holes in the roofs of these buildings).
Excellent illustrated article at Nature:
http://blogs.nature.com/news/2011/05/understanding_the_complete_mel.html
Understanding the complete meltdown at Fukushima unit 1, May 13, 2011
Here is an excerpt on the situation at No. 1 now: Clean up and beyond
Whatever happened inside unit 1, it happened weeks ago. The temperature inside the core is currently around 100C, according to the latest data from the nation's nuclear regulator—far less than it would be if nuclear reactions were continuing inside the core. But there are still some serious implications for cleanup.
The most immediate problem is for a planned recirculation system to cool the core. The plan was to feed water through two emergency systems, the core spray system and the primary containment's cooling spray system. Both are normally designed to funnel water into the core in the case of an emergency. Water exits the core through the AC piping system, normally used to inject nitrogen gas, according to Margaret Harding, an independent nuclear consultant who has been going over the plans in detail. From there, the water would flow to an improvised heat exchanger that would cool it before returning it to the core.
The recirculation system would have two big advantages. First, it would create less radioactive wastewater than is currently generated by just dumping water onto the reactor. Second, it would be more efficient, allowing the reactor to reach cold shutdown—a state where it is more-or-less safe in a matter of months.
Unfortunately, despite TEPCO continuously pumping fresh water into the containment vessel, water levels are too low for the system to work – presumably because the water's surface is below the AC outlet. Nobody really knows where all the water is going – but it can't be anywhere good. If workers can't find a way to patch up unit 1, then they'll probably have [to] give up on the plan.
In the longer term, the meltdown makes removing the fuel much more complicated. Normally, the fuel can only be accessed using a massive overhead crane. The crane has already likely been damaged by an earlier explosion, and now, if the fuel is damaged too, it's unclear whether a replacement crane can easily remove it.
Despite all these setbacks, clean up plans continue. Today, TEPCO announced that it had started initial construction of a cover for the unit 1 reactor. The temporary cover will prevent the spread of radiation, and protect the damaged reactor. Proper construction will begin on 6 June.
TEPCO unit 1 cover, From The Atlantic:
http://www.theatlantic.com/technology/archive/2011/05/meanwhile-the-disaster-at-fukushima-continues/238925/
The scary thing about a nuclear disaster like this is that here we are two months later and new (and very important) news about what happened is still coming out.
The same thing actually happened at Three Mile Island, where eight
months after the accident, an Oak Ridge National Laboratory scientist
declared, "Little, if any, fuel melting occurred, even though the reactor core was uncovered. The safety systems functioned reliably." A few years later, robotic sorties into the area revealed that half the core — not "little, if any" — had melted down.
When I wrote about Three Mile Island and the data problems they had back in 2009, I hoped that better sensors and great computing power might make it easier to understand a nuclear disaster as it happened.
As more information has emerged from Japan, it's clear that no matter how many drones and computer models we throw at a nuclear meltdown, it can still defy our capacity to understand it in real time. And that unknowability has to be incorporated into how we evaluate the risk of nuclear power disasters.
One can only ask how much of this is lack of information, how much suppression of information or even worse really, just "hoping for the best" in nuclear accidents.
Which leads us to the next information which surfaced this weekend. This is most worrying since the reactor buildings were much lauded for "withstanding" the earthquake. Apparently not! Note that TEPCO KNEW there was damage on May 11th before the Tsunami.
Quake, not tsunami, may have caused damage that led to meltdown Within 16 hours, No. 1 reactor core melted and made a hole in pressure vessel
http://enenews.com/tepco-quake-not-tsunami-may-have-caused-damage-that- led-to-meltdown-within-16-hours-no-1-reactor-core-had-melted-and-created-a-hole-in-pressure-vesselAnd
Key facilities in Fukushima plant could have collapsed before tsunami: report, Xinhua, May 15, 2011:
Key facilities at the Fukushima No. 1 nuclear power may have been damaged by the quake itself that day rather than tsunami-caused power loss that failed the reactor’s cooling function, Kyodo News quoted a utility source said Saturday.
Data taken by workers entering the No. 1 reactor building at the crippled plant on the night of March 11 showing the radiation level was as high as 300 millisieverts per hour suggest a large amount of radioactive materials from nuclear fuel in the reactor was already released. […]
Kyodo said a source at TEPCO admitted the possibility of key facilities having been compromised before the tsunami waves, saying, “The quake’s trembling may have caused damage to the pressure vessel or pipes.”
Also see NHK story today: Rapid Meltdown Occurred in Reactor
http://www3.nhk.or.jp/daily/english/16_05.html
• Meanwhile the situation at Reactor No 3 continues to worsen with rising temperatures and increased water flooding in attempt to control it.
TEPCO trying to “prevent re-criticality” at Reactor No. 3
Temperature soaring in pressure vessel, up over 100°F in 24 hours even after increasing water injection
[Sunday] May 15th, 2011 at 05:56 PM
http://enenews.com/tepco-trying-to-prevent-re-criticality-at-reactor- no-3-temperature-soaring-in-pressure-vessel-up-100-f-in-24-hours-even- after-increasing-water-injection
TEPCO announced on May 15 that it started to use boric acid in the
reactor cooling water for the Reactor 3 at Fukushima I Nuclear Power
Plant to prevent recriticality from happening. […]
[T]he temperature at the top of the Reactor 3 RPV has risen rapidly.
TEPCO increased the amount of cooling water to 12 tons per hour on May 12 using two water feeding systems, then to 15 tons per hour on May 14.
However, the temperature at the top of the RPV increased by 46.5
degrees Celsius in 24 hours to 297 degrees Celsius as of 5:00AM on May 15. TEPCO thinks there’s a problem with the pipes that feed water into the RPV.
This morning NHK announces that water will be removed tomorrow
(finally!) from No. 3. Look at the amounts of cooling water being
flooded into the reactor as reported above: 15 tons/hour. At the rate
below of 10 tons per hour removed it will take 16 days to remove 4000 tons of water. But they are flooding at a greater rate than they are removing water. Doesn't seem that the numbers work, does it?
TEPCO to move radioactive water from No.3 reactor
The operator of the troubled Fukushima Daiichi nuclear power plant says it will start transferring highly radioactive water from the No.3
reactor building to a temporary storage facility as early as Tuesday.
Tokyo Electric Power Company, or TEPCO, estimates that there is about 22,000 tons of highly radioactive water in the reactor's turbine building and in a connecting tunnel.
The utility says the water in the basement of the turbine building was about 1.4 meters high as of Monday morning, a rise of more than 20 centimeters over the past 2 weeks. Part of the water leaked into the sea last week.
TEPCO says it will move about 4,000 tons of the contaminated water to the waste processing facility. The pace of the transfer will be 10 tons per hour.
The company says it took steps to make the waste facility more
watertight, and received approval from the government's Nuclear and Industrial Safety Agency.
Monday, May 16, 2011 19:49 +0900 (JST)
http://www3.nhk.or.jp/daily/english/16_25.html
So we have cooling water at 15 tons/hr at No 3 and another story at NHK this morning announcing that cooling water at No. 1 was increased from 8 to 10 tons/hour on Sunday. http://www3.nhk.or.jp/daily/english/16_17.html
Which leads to the next very troubling story. TEPCO seems to be out of cooling options. They are "considering" . . . "studying". . . options. Also note that both the options mentioned below will require a great deal of time and additional technical development and installation to accomplish.
This all in an environment with increasing radioactivity levels where workers can't get in to do the work.
Meanwhile, flooding continues with ocean contamination on the rise . . . Not good news.
This is going to come to the crunch soon, if it hasn't already.
TEPCO to change reactor cool down method
The operator of the Fukushima Daiichi nuclear plant says it will change the method being used to cool 3 reactors now that it's been found the fuel rods in the No. 1 reactor have melted down.
Tokyo Electric Power Company says the meltdown is believed to have created holes in the pressure vessel protecting the reactor core and damaged the containment vessel.
As a result, highly radioactive water may be leaking from the containment vessel to the basement of the No. 1 reactor building.
TEPCO also says the gauges at the No.2 and 3 reactors might not be showing the actual water levels and that both reactors are likely to have undergone meltdowns.
The utility says the situation makes it difficult to fill the containment vessels of the reactors with water as planned, and that an alternate cooling method will have to be found.
It says it is now considering pumping water out of the containment
vessels and circulating it back into the reactors after chilling it with heat exchangers.
Another method under study is pumping water from the basement and sending it back to the reactors after radioactive substances have been removed.
Despite these developments, TEPCO says it will keep to its timetable of achieving cold shutdown in 6 to 9 months. The utility is to announce on Tuesday an updated plan for bringing the crisis under control.
Monday, May 16, 2011 21:53 +0900 (JST)
http://www3.nhk.or.jp/daily/english/16_32.html
Radioactivity at intake of No.3 reactor rises
Radioactive materials in the ocean near the Fukushima Daiichi nuclear power plant rose to 3,300 times the legal limit on Sunday.
Tokyo Electric Power Company says it measured 200 becquerels of
cesium-134 per cubic centimeter on Sunday morning near the water intake of the No. 3 reactor. The level was higher than on the previous day, when it was 2,300 times the legal limit.
220 becquerels of cesium-137 per cubic centimeter was also detected. At 2,400 times the legal limit, the level exceeded the one found the day before.
On Wednesday, highly radioactive water was found leaking into the ocean from a pit located near the water intake of the No. 3 reactor. 32,000 times the legal limit of cesium-134 was detected there.
TEPCO also reported 2,100 times the legal limit of radioactive iodine was found in seawater near the water intake of the No. 2 reactor. Three points among four research areas along the shoreline also exceeded the legal limit. And 1.7 times the legal limit of Cesium was found close to drainage gates near the No. 5 and No. 6 reactors.
TEPCO says the changes in readings are within a margin of day-to-day volatility. [HUH?]
Monday, May 16, 2011 05:31 +0900 (JST)
http://www3.nhk.or.jp/daily/english/16_06.html
I'll leave you a final link to check out: Asian Week, the Voice of Asian America. Tip of the hat to Kevin who sent this through last night: http://www.asianweek.com/2011/05/16/fukushima-happiest-nuclear-power-plant-in-the-world/
First you'll see Fukushima, Japan's Happiest Nuclear Power Plant, a video made to "educate the public when Fukushima was built (with English subtitles). Then a great article: Making Sense of Ruined Reactor Pictures