Status of the Fukushima Reactor Accidents
BY Herschel Smith
13 years, 9 months ago
The Telegraph has some useful video that shows the damage to Fukushima Nuclear Power Plant.
ANS Nuclear Cafe gives us a rundown of the status of Fukushima reactors (and a little information on the Spent Fuel Pools).
FEDERATION OF ELECTRIC POWER COMPANIES OF JAPAN March 17, 2011, 14:15 GMT Update regarding the Tohoku earthquake
Radiation Levels
- At 9:20AM (JST) on March 17, radiation level at elevation of 1000ft above Fukushima Daiichi Nuclear Power Station: 4,130 micro sievert.
- At 9:20AM on March 17, radiation level at elevation of 300ft above Fukushima Daiichi Nuclear Power Station: 87,700 micro sievert. At 11:10AM on March 17, radiation level at main gate (approximately 3281 feet from Unit 2 reactor building) of Fukushima Daiichi Nuclear Power station: 646.2 micro sievert.
- At 7:50PM on March 17, radiation level outside main office building (approximately 1,640 feet from Unit 2 reactor building) of Fukushima Daiichi Nuclear Power Station: 3,599 micro sievert.
- For comparison, a human receives 2,400 micro sievert per year from Natural radiation in the form of sunlight, radon, and other sources. One Chest CT scan generates 6900 micro sievert per scan.
- Fukushima Daiichi Unit 1 reactor
- Since 10:30AM on March 14, the pressure within the primary containment vessel cannot be measured.
- At 12:50PM on March 17, pressure inside the reactor core: 0.185MPa.
- meters below the top of the fuel rods.At 12:50PM on March 17, water level inside the reactor core: 1.
- Fukushima Daiichi Unit 2 reactor
- At 12:25PM on March 16, pressure inside the primary containment vessel: 0.40MPaabs.
- At 12:50PM on March 17, pressure inside the reactor core: -0.027MPa.
- At 12:50PM on March 17, water level inside the reactor core: 1.8 meters below the top of the fuel rods.
- Fukushima Daiichi Unit 3 reactor
- At 12:40PM on March 16, pressure inside the primary containment vessel: 0.23MPaabs.
- At 6:15AM on March 17, pressure inside the suppression chamber was observed to fluctuate.
- At 7:00AM on March 17, pressure inside the suppression chamber: 0.22MPa.
- At 7:05AM on March 17, pressure inside the suppression chamber: 0.44MPa.
- At 7:10AM on March 17, pressure inside the suppression chamber: 0.26MPa.
- At 7:15AM on March 17, pressure inside the suppression chamber: 0.52MPa.
- At 7:20AM on March 17, pressure inside the suppression chamber: 0.13MPa.
- At 7:25AM on March 17, pressure inside the suppression chamber: 0.57MPa.
- At 9:48AM on March 17, a Self Defense Forces helicopter made four water drops aimed for the spent fuel pool.
- At 4:35PM on March 17, pressure inside the reactor core: 0.005MPa.
- At 4:35PM on March 17, water level inside the reactor core: 1.95 meters below the top of the fuel rods.
- At 7:05PM on March 17, a police water cannon began to shoot water aimed at the spent fuel pool until 7:22PM.
- At 7:35PM on March 17, five Self Defense Forces emergency fire vehicles shot water aimed at the spent fuel pool, until 8:09PM.
- Fukushima Daiichi Unit 5 reactor
- At 2:00PM on March 16, the temperature of the spent fuel pool was measured at 145 degrees Fahrenheit.
- Fukushima Daiichi Unit 6 reactor
- At 2:00PM on March 16, the temperature of the spent fuel pool was measured at 140 degrees Fahrenheit.
Notice the pressure inside the Unit 1 reactor vessel: 0.185 MPa, which is 26.834 psi. Units 2 and 3 are lower, essentially atmospheric pressure, and Unit 4 isn’t even included in the report. The NRC has some hypothetical dose projections (that are in my opinion far too high, and I don’t believe them), but it isn’t difficult to see why the NRC has recommended evacuation for U.S. citizens.
Help is on the way, and they hope to install and align emergency power soon. It wasn’t long after the tsunami that they had portable emergency diesel generators delivered, but the tsunami had cleared out all offsite power, including stepup transformers and connections. They literally had nothing to which to connect (that could be readily ascertained as the power source for any specific component). It was a jungle of cables.
But it’s important that everyone realize what I have already said concerning this set of accidents. The main stream media (both print and television) continue to point towards avoiding a core melt event, as if it will announce itself with some sort of trumpet blast and melt through the earth. As I have explained, it doesn’t happen that way. The corium, if it makes it through the lower reactor vessel head, will disperse and cool from that dispersal, not even making it through the lower basemat of concrete.
The cores for Units 1, 2 and 3 are already damaged. They are partially melted, and partially shattered and rubblized, sitting in the lower part of the reactor vessel. Most of the radiological source term that can be expected to be released from the core to containment has already been released. It is being held up inside hard containments and depleted via radioactive decay, plateout, etc.
The work now has to do with mitigation of the radiological source terms, from water injection into the reactor coolant system, water washdown of plant components, and so on. If the semi-volatile fission products and alkali metals are in effluent, they will likely not re-evolve to the atmosphere in large quantities. Most importantly, for now, the Spent Fuel Pools deserve attention, and hopefully the operators will be able to mitigate zirconium fire events in the pools.
The Japanese are performing heroically, and the main stream media will catch up in several days (or weeks). The current efforts are focused on radiological source term and thus dose mitigation, not the prevention of core melt events.
Prior:
Further Degradation of Fukushima Unit 4 Spent Fuel Pool
Spent Fuel Pool Fire At The Fukushima Nuclear Power Plant?
Primer for Studying News Releases on the Japanese Reactor Accidents
On March 17, 2011 at 11:07 pm, John D said:
Thanks for some non-hysterical reporting. But I find your assertion that the MSM will ‘catch up’ to be a trifle over optimistic. They will continue reporting this accident in end-of-the-world terms until the next Charlie Sheen comes along, then they’ll drop it.
On March 17, 2011 at 11:08 pm, Nehemiah H. Leftwich said:
Just one thing . . . these were not ACCIDENTS. Rather, they were casualties of two horrific natural disasters.
On March 17, 2011 at 11:13 pm, Herschel Smith said:
Yes, Nehemiah, you’re absolutely correct. It’s important to remember that, although these “events” do fall within the category of DBAs/DBEs (design basis accidents / design basis events) normally contained and analyzed in the design basis documents and UFSARs of nuclear reactors. Either way, it’s a mere formality.
On March 17, 2011 at 11:19 pm, Jack P said:
Echoing John D, it’s great to read a synopsis from someone who clearly understands the details, and is able to translate it for us non ‘Nuke-u-lar’ types…
On March 17, 2011 at 11:35 pm, D Huber said:
I knew it all along. The media, all of them, can turn an evening of light showers into the storm of the decade given enough time and camera angles along with a dufus on the ground guy splashing around in water puddles.
On March 17, 2011 at 11:37 pm, david said:
What is a fatal dose?
Are the workers there becoming ill?
In the big picture of the deaths involved in this natural disaster, if they do die, it is insignificant to the final toll, I realize, but the guys that are on the plant site have to be recognized for their extrodinary bravery in what appears to be a suicidal(?) rescue effort on these reactors.
I think the media has not covered this well, compared to just their coverage on air travelers having microscopic amounts of radilogic dust coming off incoming flights.
Thanks for a basic overview of what is being done on-site from a nuclear neophyte
On March 17, 2011 at 11:39 pm, Jay R said:
what do the pressures tell us about the condition of the reactor and the containment structures?
On March 17, 2011 at 11:42 pm, Jason said:
Should “4,130 micro sievert” and the other radiation levels have “per hour” appended?
On March 17, 2011 at 11:43 pm, Herschel Smith said:
The pressures tell us that the Reactor Coolant System is depressurized, and that the system has sustained a LOCA (loss of coolant accident), and that they likely do not have subcooling margin. It tells you that they have already sustained core damage.
On March 17, 2011 at 11:46 pm, Herschel Smith said:
Jason, yes. That has been one of my complaints all along. The MSM (all of them, and in this case, utility PR) doesn’t report dose in units of time. It’s maddening. Maybe they should take some physics and engineering classes before they report on physics and engineering. Just a thought, you know?
On March 18, 2011 at 12:27 am, rick said:
Hershel,
If they could pass physics and engineering, they wouldn’t be reporters.
On March 18, 2011 at 12:49 am, Andrew said:
Besides lacking a rate, I would venture to guess the ‘microsieverts’ are really supposed to be ‘millisieverts’ — unless it is something like microsieverts/sec.
On March 18, 2011 at 1:25 am, John said:
Thank you. Nice to see some actual measurements (even if I am having to convert them to rem) the media had been driving me bat shit with the 1000x normal reporting, and the front page wall street journal which gave a measurement in ‘micro sieverts per house’.
On March 18, 2011 at 1:28 am, Zoe Brain said:
Andrew – no, it’s uSv/hr not mSv/hr.
Personally, I consider 8.77 Rem/hr quite scary enough, thanks very much. It means that in order to have no detectable health risk whatsoever, exposure times must be in 10s of minutes at most.
So far it *appears* we’ve had no radiation casualties, and not even anyone who’s taken more than 25 Rem. Let’s keep the casualty rate from radiation zero.
OTOH even 0.6462 mSv/hr is way above the 0.06 mSv/hr I consider negligible for long-term exposure. We can’t just ignore this.
On March 18, 2011 at 4:44 am, james said:
Great site information and comments. The MSMs’ incompetence on engineering and science is the same for military subjects.
On March 18, 2011 at 4:59 am, scott s. said:
Nice summary, though I’m having trouble getting through the idea that the RPV pressure is so low. I would think that as long as there is residual heat and at least some coolant, that there will be steam production and some pressure, unless the RPV is being vented into the containment/drywell. It seems that diesel generator power is being made available to units 5/6 and they are going to align the SFP heat removal systems (first in 6 then 5) and get that back into normal range, then restart LPCI. Meanwhile off-site power is being brought into unit 2 for at least control and instrumentation. From what I’ve read I guess the total loss of electric power made it impossible to manage the hydrogen gas production. It seems besides the obvious question of how big an earthquake/tsunami you design for, handling of H2 in different accident scenarios needs review.
On March 18, 2011 at 6:23 am, Blunt Instrument said:
@david
Anything above 5000 millisieverts (5,000,000 microsieverts) is fatal.
On March 18, 2011 at 8:23 am, John said:
I think that’s around 500 rem, which would equate to about an LD/50. 1000 Rem would be an LD/100. Of course those are one time exposures, if you did it over the course of several years, then this wouldn’t apply.
On March 18, 2011 at 9:48 am, Warbucks said:
Herschel, What is the possibility of designing a reactor core fuse where if a melt-down is the next event, the core is flushed with molten lead and stirred into a dissipated state, extracted, sealed and buried?
On March 18, 2011 at 11:52 am, submandave said:
For general information (especially for old farts like me who still think in rem instead of Sv), 1 Sv = 100 rem. So 87,700 uSv @ 300 ft = 8.77 rem/hr, as Zoe points out. I concur that such levels are significant, but am interested upon what source you have for assering that 1 rem exposure poses a “detectable health risk.” IIFC, symptoms from acute radiatin doses generally are not expected at all below 10 rem and may not manifest until up to 100 rem depending upon the affected individual.
@david, as others have said, 500 rem (or 5 Sv, if you prefer) is generally used as the LD50/30 level. LD = lethal dose, and it means that 50% of people who receive this whole body dose in a short period of time are expected to die over the next 30 days. The highest individual exposure I’ve read of is ~25Rem, which may produce radiation poisoning symptoms. For most personnel, I would venture to guess that the carcinogens in the smoke and aerosol metals pose a greater long-term health risk than the radiation exposures they are receiving.
On March 18, 2011 at 11:57 am, submandave said:
@Warbucks, the problem w/ meltdown is nto one of increasing reactivity or radioactivity, but one of controlling decay heat (the monster they’ve been fighting since the LOFA). With a meltdown, normal cooling flow through the material is destroyed, meaning there is no effective mechanism for removing the decay heat from the material in the middle of the corium pile. The meltdown will not, in itself, cause the material to become more radioactive or add reactivity to the pile. The danger comes from from an increase in the potential for an uncontrolled release of radioactive materials.
On March 18, 2011 at 12:13 pm, Scott Rainey said:
Can any of you learned souls address how much power is needed to run the pumps that cool a reactor and how much a portable gen-set capaple of that many watts would weigh?
I assume since there was no helicopter lift/delivery of such a gen-set that it’s too heavy for even the 10-ton capacity of a S-64 skycrane. But what about hovercraft delivery since the reactors are so close to the ocean?
On March 18, 2011 at 12:37 pm, Herschel Smith said:
Submandave, yes, and a thousand times yes. I hate the unit of Sv, and I think that it is dopey and goofy. Every time I see units of Sv, mSv or uSv, I immediately convert it to Rem. No need for any other unit, and even ANS publications, while using SI units on everything else, specifically allows units of Rem. Why? Because Sv is a goofy and unnecessary unit of measurement. Or did I say that already?
And yes, the concern Warbucks is removal of decay heat, and while Submandave is right about it likely not significantly changing reactivity of the partially shattered / partially melted core, from a wonkish perspective, it’s possible to change the geometry enough (from a lattice to a pile) to get different Keff answers with MCNP or KENO.
On March 18, 2011 at 12:49 pm, David Robson said:
I am most grateful for your encouraging report. My Japanese wife has friends in Tokyo and I can now assure them that there is a very high probability of getting the problem under control and that pre-emptive doses of iodine should be enough for any minor fallout that makes it as far as there
On March 18, 2011 at 2:20 pm, Warbucks said:
Herschel, thanks for entertaining my “meltdown-fuse” idea. The is a worst case solution that closes the plant for ever. But the system would have to do the following:
(a) Provide auxiliary fusing materials (molten lead) when needed.
(b) Probable mix this material into the core using gravity to do the mixing (assuming everything by thing is inoperable)
(c) Spill into a deep “containment hole” leaving the its mixture with the molding lead sealed for 10,000 years plus.
(d) There has to be enough fusing material (molted lead) to disperse the radio active materials in the rods (maybe rods could also be redesigned for use in this sort of reactor) so that critical state is reduced to sub-critical state and the system begins to cool.
On March 18, 2011 at 3:20 pm, Warbucks said:
Here’s a schematic http://i237.photobucket.com/albums/ff24/BayProductions/ReactorDesign.jpg
On March 19, 2011 at 7:03 am, D. Lively said:
Thanks for the honest and informative posts. I live just northwest of Tokyo (about 150 miles from the Fukushima plant) and the reports we get are either “Remain calm. All is well. Pay no attention to those hydrogen explosions.” or “The Monster! Godzilla! Run for your lives! Run! Run! Run!”
Also, we keep hearing reports about panic buying. If it’s caused by panic, it’s the calmest panic I’ve ever seen. Yes, people are stocking up before the rolling blackouts–it’s actually easier to get meat and vegetables than a flashlight and batteries right now–and there are resupply and fuel problems. Many stores have imposed their own rationing–letting only a dozen people in at a time and limiting the amount of one item people can buy–but every waits patiently for their turn.
For what it’s worth, according to the news this morning, more people have died from blackout related incidents (3) than from radiation (0).
In our area, we have inconveniences and some small annoyances that are slowly going away. We watch the reactors with some caution, but our eyes are really focused toward the northeast, where the real problems are.
Thanks to everyone for keeping Japan in their thoughts and prayers.
On March 20, 2011 at 8:19 am, Warbucks said:
Subject: Japan Devastation report from behind the scenes
This from the CO of Marine Corps Air Station, Futemna, Okinawa,
Colonel Dale Smith. Several forwards have been deleted.
Quick note to let you know what’s happening and a sincere “thanks” for
yournote of concern…it’s not taken for granted and appreciated greatly.
We worked all weekend…(Air Station is normally limited hours
onSaturday’s, closed Sunday’s)…open 24/7 now in support…our guys/gals
willbe fairly ragged soon.
MEF pushed 8 Phrogs and 10 or more C-130s North to Iwakuni over the weekend.
A Joint Task Force (JTF) was established by USFJ…led by Army 3-star;
hisdeputy is the Division’s CG…(our guy), a 2-star select.
31st MEU is inbound…MEB has moved forward as well…JTF will attempt
toestablish its HQ at Sendai Airport once they can get in there and clear
somethings….(but a third reactor just blew, not sure how close they get
justnow). Devastation truly is “atomic equivalent” in nature….entire
villages(cities)..gone, “everyone” within their populations (in some
cases10,000)…missing or dead. Damage isn’t isolated to just
Sendaiarea….over 10 cities we’re taken “out”….gone, off the map, along
withtheir people. I cannot write this without tears…it’s that bad.
Helos from Oki, Korea, supporting…with as many fixed-wing as possible
aswell…all branches of service. Flew all weekend myself, along with
ourother OSA aircraft (3 jets, 1 C-12 from Oki), Two C-12s from
Iwakuni,getting people up to Yokota (Tokyo area), Iwakuni, Atsugi, etc….
Most willmove forward into the disaster area when able to support what
will no doubtbe a very long recovery process and HADR ops. My XO is
flying today…(Iwas scheduled to, but was pulled off the sched to support
other ops). XO isflying the Generals over the latest reactor explosion
area…(above what’snow becoming a nuclear cloud). USS Ronald Regan
floated through the “cloud”yesterday and became contaminated to a degree.
Helo’s are doing the same,and have to be “decon’d” upon returning to
base….rescuers and victims arebecoming “exposed” to the radiation, and
unfortunately for now, the endisn’t in sight as to how bad the
nuclear situation will get.
Thanks again Horn….I’ll keep you updated when I can. Appreciate
theprayers for all….(wx’s been good, but rain and snow are moving into
todayup there, as if the people weren’t suffering enough). At times like
this,all one can do is their best, and remember, God has a plan we
sometimesdon’t understand, but have to trust, He’s in control.
Semper Fi,Smitty