dragonstar57 Posted March 16, 2011 Author Posted March 16, 2011 heard something about "exposed fuel rods on CNN but wasn't able to see the report idk if they ment exposed as in some kind of reactor breach or coolant no longer covering the rods any one else hear about this?
Cap'n Refsmmat Posted March 16, 2011 Posted March 16, 2011 Yes, the coolant water had boiled off and left the rods exposed, but they were still inside the containment vessel last I checked. News reports are rather scattered and contradictory right now.
ewmon Posted March 17, 2011 Posted March 17, 2011 I just found this really nice article: US alarm over Japan atomic crisis (BBC News, Wednesday 16 March) Over the days of the Fukushima crisis, attention has switched from reactor building 1 to 3, to 2, back to 3 - and now, to 4. This is a surprise. Reactors 4, 5 and 6 were shut down at the time of Friday's earthquake, with some or all of their fuel rods extracted and left in the cooling ponds that each reactor building has under its roof. Once a reactor is turned off, radioactivity and heat generation in the rods die away quickly; down to 7% of the original power within a second of switch-off, 5% within a minute, 0.5% within a day. Transferred to the cooling pond, allowing technicians to do routine maintenance on the reactor, the rods are supposed to sit quietly until the time comes for their re-insertion or their journey towards disposal. The tops of the rods are supposed to be about 5m (16ft) below the water surface. The water keeps them cool and also blocks radiation. Over the last few days there have been reports suggesting water levels were low and the water "boiling"; and now the US Nuclear Regulatory Commission (NRC), which has a team of 11 experts advising in Japan, says the pool is completely dry. This means the fuel rods are exposed to the air. Without water, they will get much hotter, allowing radioactive material to escape.
moth Posted March 17, 2011 Posted March 17, 2011 I was just wondering if anybody knows whether any monitoring was done after the atomic bombs dropped on Hiroshima or Nagasaki to see if radiation reached the U.S.? Short of a China syndrome type of meltdown or a fire in the spent fuel holding ponds, I'm guessing much more radiation was released from the bombs, is that correct?
Mr Skeptic Posted March 17, 2011 Posted March 17, 2011 heard something about "exposed fuel rods on CNN but wasn't able to see the report idk if they ment exposed as in some kind of reactor breach or coolant no longer covering the rods any one else hear about this? It seems one of the rods lost sufficient coolant that it overheated and got some damage, which let some of the fission products dissolve in the coolant water. It's not really all that dangerous, but really shouldn't happen. If something else goes wrong then it could be a problem.
Blahah Posted March 17, 2011 Posted March 17, 2011 If anyone is interested in keeping up to date with the latest, there are now several websites with daily updated radiation readings from around Japan. The Ministry of Education is providing this PDF (in English): http://i.yimg.jp/images/tecblog/emg/pdf/0316/110315fukushima_2030_en.pdf The Bousai news agency has this interactive map (in Japanese, but the numbers are obvious): http://www.bousai.ne.jp/vis/index.php and the TEPCO site (the company who operates the plants) is now showing readings from their monitoring stations around the plant (Japanese, obvious numbers): http://www.tohoku-epco.co.jp/electr/genshi/onagawa/mp.html Units are all in nGy/h (which is nanoGray/hour, 1 nanoGray/hour approx = to 1 nanoSievert/hour or 0.001 microSievert/hour)
swansont Posted March 17, 2011 Posted March 17, 2011 I was just wondering if anybody knows whether any monitoring was done after the atomic bombs dropped on Hiroshima or Nagasaki to see if radiation reached the U.S.? Short of a China syndrome type of meltdown or a fire in the spent fuel holding ponds, I'm guessing much more radiation was released from the bombs, is that correct? I seriously doubt there were monitoring stations prior to there being nuclear bombs and power plants.
FX Posted March 17, 2011 Posted March 17, 2011 There doesn't seem to be any monitoring stations in Japan itself. Certainly none around the nuclear plants.
Blahah Posted March 17, 2011 Posted March 17, 2011 There doesn't seem to be any monitoring stations in Japan itself. Certainly none around the nuclear plants. If you care to look just two posts up, you'll see I posted three links which allow you to see the readings from dozens of different monitoring stations in Japan, including those surrounding the plant.
jackson33 Posted March 17, 2011 Posted March 17, 2011 Figures provided by Tokyo Electric Power on Thursday show that most of the dangerous uranium at the power plant is actually in the spent fuel rods, not the reactor cores themselves. The electric utility said that a total of 11,195 spent fuel rod assemblies were stored at the site. That is in addition to 400 to 600 fuel rod assemblies that had been in active service in each of the three troubled reactors. In other words, the vast majority of the fuel assemblies at the troubled reactors are in the storage pools, not the reactors. [/Quote] http://www.nytimes.com/2011/03/18/world/asia/18spent.html As I "currently" understand it reactor #4, WAS shut down and it IS the stored (spent) rods causing the problem. Multiple redundant diesel generator systems. Large batteries. Access to the local electrical grid. Steam turbine backup systems that used the residual heat and steam to pump more water into the reactor. Mobile replacement generators arrived soon after the incident. As I said, the electrical switching area was in the basement and flooded, so connecting the new generators to the electrical systems was difficult. [/Quote] The quotes are from CR, agreed to by swansont, but if anyone can answer the question I've been asking from the start, please do so.... If all back up systems for cooling rods or keeping water circulating, if large batteries were on hand, not damaged during flooding and replacement generators were sent to the sites, how could those now saying a new power line from their power grid could resolve the problems, have any meaning???
swansont Posted March 17, 2011 Posted March 17, 2011 If all back up systems for cooling rods or keeping water circulating, if large batteries were on hand, not damaged during flooding and replacement generators were sent to the sites, how could those now saying a new power line from their power grid could resolve the problems, have any meaning??? "If all back up systems for cooling rods or keeping water circulating" doesn't seem to be a proper sentence (or phrase), so I don't know what you are asking. The batteries were drained. Cap'n had posted that there were problems tying the generators in; the switch gear where they would tie in may have been flooded. The message I get from this is that has not been power to the main pumping systems — they were operating on backup systems and when those went down, they then relied on pumping seawater into the buildings to cool the containment vessels from the outside. I don't know for sure if they were injecting seawater into the core at one point; the reports aren't clear on this. But for sure using helicopters to dump water means they aren't doing this to get water into the main cooling loop that goes to the reactor. Restoring power means restarting the main cooling and charging pumps, which means direct cooling of the core and replenishing the water in the core.
CharonY Posted March 17, 2011 Posted March 17, 2011 (edited) All I can say is that of the physics I know and facts I can verify, I only had one quibble with the post, that he called control rods moderator rods. That doesn't jibe with my navy experience. Excellent. The blogpost was nicely written for laymen like me to understand, though with my knowledge I could not easily validate accuracy. The quake and tsunami are devastating disasters that need international help. The problems with the reactor(s) are rather less important yet they seem to be the focus of attention. Indeed. Edited March 17, 2011 by CharonY
Blahah Posted March 17, 2011 Posted March 17, 2011 (edited) If all back up systems for cooling rods or keeping water circulating, if large batteries were on hand, not damaged during flooding and replacement generators were sent to the sites, how could those now saying a new power line from their power grid could resolve the problems, have any meaning??? This has already been explained several times. I'll say it again: The batteries were used until they ran out Backup generators were knocked out by the quake The electrical control room was flooded by the tsunami Replacement generators which were sent to the site could not be connected because of the flooded basement and because they could not connect them to the system at the plant Now they are working to restore the electrical control room to a safe working condition and to ensure a reliable connection to the power grid can be made so they can restore power to the water pumps for the cooling system, which should bring the problem under control. @swansont yes they were directly pumping seawater into the buildings for a couple of days, using fire hoses. They are still doing this at two sites, but they stopped at two others sites because they were failing to get sufficient quantities in and it was not worth risking the radiation exposure of staff for the minimal effect it was having. They want to flood the exposed spent rods at reactor 4, hence the helicopter drops. Edited March 17, 2011 by Blahah
FX Posted March 18, 2011 Posted March 18, 2011 http://www.tohoku-epco.co.jp/electr/genshi/onagawa/mp.html Numbers haven't changed all day. I am suspicious of the accuracy. http://www.bousai.ne.jp/vis/index.php Numbers don't update, most important station not reporting. If that is the extent of their monitoring stations, things are worse than I thought.
louis wu Posted March 18, 2011 Posted March 18, 2011 One thing that I have not seen mentioned here, might be a factor in the poor usage of shipped in generators. Japan actually has 2 completely separate grid systems, one for the East of the country and one for the West. One side runs on 50Hz and the other side at 60Hz. Equipment from the non tsunamied West of the country is probably unusable on the East side of the country. I am not an electrical engineer but a frequency switch for equipment is probably very difficult without rectifying AC to DC and then back to AC at the new frequency. Components to do this for presumably 3 phase diesel generators would be hard to source.
Blahah Posted March 18, 2011 Posted March 18, 2011 http://www.tohoku-ep...onagawa/mp.html Numbers haven't changed all day. I am suspicious of the accuracy. http://www.bousai.ne.jp/vis/index.php Numbers don't update, most important station not reporting. If that is the extent of their monitoring stations, things are worse than I thought. The graph in the first link has been updated every 6 hours for the last 5 days. The numbers have changed slightly as the graph shows. The numbers on the map in the second link are updated daily. The pink dots indicate stations which were cut off from the network in the earthquake/tsunami and are currently being repaired. Obviously those aren't all the monitoring stations in Japan, there are at least 6 at each of the 51 reactors, then most universities also have them and a whole network of others run by TEPCO and various agencies. The map shows the stations which that particular news agency has access to. But at the moment most people have more to worry about than whether foreigners believe the data they are openly publishing.
FX Posted March 18, 2011 Posted March 18, 2011 Number still haven't changed. This entire overwhelming lack of actual data was at first surprising, then I remembered, we are dealing with radiation, and governments, and there is little chance of science winning when it comes to politics.
michel123456 Posted March 18, 2011 Posted March 18, 2011 (edited) Yes. Some other example:(emphasis mine) "On 15 March, at 11:51 JST Japan suspended operations at the stricken Fukushima I nuclear plant after a surge in radiation made it too dangerous for workers to remain at the facility.[163] However, workers returned about an hour later after radiation levels decreased[158]. ??? levels decreased??? and As of 16 March 2011 (2011 -03-16)[update], five plant workers have died and 22 others have been injured. Two others are reported missing.[164] The government raised the national safety standard governing radiation exposure from 100 to 250 mSv per year, so plant workers could continue their work."[165] No comment. From the wiki page. I wonder who keeps this page so well up to date? Edited March 18, 2011 by michel123456
jackson33 Posted March 18, 2011 Posted March 18, 2011 One thing that I have not seen mentioned here, might be a factor in the poor usage of shipped in generators. [/Quote] louis; I almost hope you were kidding, as I've been on this from the day this thread was made, without any IMO, satisfactory explanation (anyplace, not just this forum). You have however offered one possibility, if the reactors are powered by 3-Phase and I don't know, nor do I know if fuel powered generators can be set up for three phase. I'd believe they could be since my only experience with this is adding one line to existing to a 2 phase system. Anyway I find it hard to believe, the people involved would send in generators that could not be used and AC generators are a dime a dozen. There must be some reason why they were not used and I'm suspecting the main problems were not originally in the primary containment units, but in the stored spent rods.... The so called "half mile extension cord", is also taking a extraordinary amount of time and last I heard was only going to used, on 2 of the troubled reactors.
swansont Posted March 18, 2011 Posted March 18, 2011 Anyway I find it hard to believe, the people involved would send in generators that could not be used and AC generators are a dime a dozen. There must be some reason why they were not used and I'm suspecting the main problems were not originally in the primary containment units, but in the stored spent rods.... The main coolant pump for the AP1000 system (warning: pdf. it's what I could find, so not necessarily the one in use but should be representative) is rated at 7000 HP, which is a little over 5MW. That's just one pump; the BWR drawings show three feedwater pumps, though I imagine only one would need to be running in shutdown, and not at full speed. This doesn't count other systems that would need to run. So we're talking about MW-capacity generators. And a system designed to run in a specific voltage range. A problem, as has been explained a few times, is where you hook them up. If the switchgear was destroyed or submerged, this is a problem. You don't just plug in a ~10 kV line carrying ~100 Amps with an extension cord.
Blahah Posted March 18, 2011 Posted March 18, 2011 (edited) Number still haven't changed. This entire overwhelming lack of actual data was at first surprising, then I remembered, we are dealing with radiation, and governments, and there is little chance of science winning when it comes to politics. That comment is inaccurate if you're implying that governments cover up radiation. It's impossible to cover it up - any person can make their own radiation readings and publicise them. Also how is it surprising that a country which just had a huge portion of its infrastructure wiped out, and is in the process of one of the largest humanitarian responses ever carried out by a single government, was slow to make foreign media aware of radiation readings so they can all panic about it? I think it's fairly understandable. Actually you are right that the TEPCO site hasn't updated the numbers today, but the MEXT (Japanese Department of Education) have a team putting together PDFs of radiation monitoring data from all the public access stations downwind of the plant: http://eq.wide.ad.jp/index_en.html Many of them are also in English, although it seems the volunteer translation team is working a few PDFs behind the data publishing team. For example, here is the latest data (Japanese PDF): http://eq.wide.ad.jp...ushima_1900.pdf The columns read as follows: The number of the recording station in brackets, followed by the linear distance from the Fukushima site and the direction (asee below) The time and date of the reading (bsee below) The radiation reading in microSv/hour The weather conditions The data source a Compass directions in Japanese are: 北 = north, 西 = west, and combinations thereof can be directly translated (e.g. 北西 is north west) - you don't need others to interpret this PDF as the wind is blowing towards the north west. b 3月18日13時45分 means 3rd month, 18th day, 13th hour, 45th minute; i.e. 18th March, 13:45. At the bottom of the PDF you can see a map showing the last 3 readings at each site. Site 32 is much higher than all the others, at 150µSv/h. Other PDFs linked from the site show data for other areas of Japan - if you want to know what something means just ask. Edited March 18, 2011 by Blahah
jackson33 Posted March 18, 2011 Posted March 18, 2011 swansont; Thanks, a very informative, descriptive display of the cooling system. I'll study it further later tonight but still feel power generators are/were available to hook up directly to that one part of the process. It also appears if I've read it correctly, the steam generation would have continued (to some degree) with out power, as steam release out of the plant was shut down allowing some natural forced energy. I also noted a different power requirement for certain jobs, so any power could have (I don't know) might have helped. For instance, if you lose 220 power, you 220 A/C 110 fan motor will continue to run... As said earlier, in my mind and technically everything worked according to plans except for the spent rods being held, where ever that was. I kind of follow markets, judging internal national affairs, probably too much, but if correct whatever is going on in Japan, those markets are not concerned. They open each day 6PM ET and last night opened up 300+ around 9227, not far at all from recent highs.
FX Posted March 18, 2011 Posted March 18, 2011 The top Japanese officials have admitted that the plant has been releasing deadly radiation for a while now, and expressed deep remorse for not telling anyone sooner. No US officials were surprised.
Blahah Posted March 18, 2011 Posted March 18, 2011 (edited) The top Japanese officials have admitted that the plant has been releasing deadly radiation for a while now, and expressed deep remorse for not telling anyone sooner. No US officials were surprised. Do you have a source for that? 'Deadly radiation'? 'A while now'? Sounds like you just made it up. Edited March 18, 2011 by Blahah
jackson33 Posted March 18, 2011 Posted March 18, 2011 The boss of the company behind the devastated Japanese nuclear reactor today broke down in tears - as his country finally acknowledged the radiation spewing from the over-heating reactors and fuel rods was enough to kill some citizens.[/Quote] Read more: http://www.dailymail.co.uk/news/article-1367684/Nuclear-plant-chief-weeps-Japanese-finally-admit-radiation-leak-kill-people.html#ixzz1GytLRBVX
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