This information is a few days old, as I have been travelling, but as I have done several times already, please allow me to share with you the UK's Chief Scientific Advisor, Sir John Beddington's of April 7th. It is a good overview, and shows that things are slowly getting better with regard to the nuclear plant issue;
Fukushima:Overview
Sir John begun the briefing by saying that we should not relax completely on the subject of Fukushima - the situation is still serious – but that there has been significant progress. This “progress” is the reason why the FCO travel advice was relaxed last night. Sir John explained that the Japanese have now established power to the nuclear plant and are using fresh water to cool the reactors. These two facts, coupled with the natural progressive decay of iodine, mean that any effects of radiation are significantly reduced. From time to time, Sir John went on, there will be small releases of radiation into the environment, but this will be nothing like the radiation produced by the meltdown of a reactor or an explosion in a fuel pond. TEPCO is now injecting nitrogen into the main containment unit – mainly unit 1 – in order to cut down the possibility of hydrogen based explosions. Sir John says that the UK supports this move and urged that people should not be alarmed by resultant steam that will sometimes emit from the plant. This is a natural side effect of the hydrogen injections. In summary, the practical actions taken by the Japanese – connecting power and using fresh water – coupled with the natural processes of iodine 131 decaying, mean that the situation at Fukushima is improving in general. Sir John assured that the threat of radiation to the Tokyo region has significantly reduced.
Q: Can you say something about the continuing concerns about food and water from the area?
Sir John and his colleagues from the UK’s Health Protection Industry and the Department of Health, reiterated that significant amounts of radiation have been released into the water, and that seafood from the Fukushima area should not be eaten; the risk to Tokyo has disappeared. People are urged to take their lead from the guidance of the Japanese government.
Land contamination
The briefing went on to cover the issue of land contamination – there are high concentrations of radioactivity on agricultural land. It might be possible for people to live in certain areas, but the soil there might be contaminated for months or years to come. Sir John and colleagues continued: the Japanese will put legislation in place to make sure that food from these areas does not get into the food chain. We were reminded that it is “still early days” but that Japanese regulations are more stringent than those of other countries.
Q: There is concern over milk, eggs, dairy products, etc. Is there anything you can say about that?
Sir John reinforced the fact that the Japanese will continue to test food, and that their regulations are stringent; this means that any detection of radiation will quickly become apparent. The primary concern was radioactive iodine; cesium getting onto the soil is also an issue. But the latter is easy to detect and regulate, it was assured. Milk may be banned in a wider area, even in areas that people can live quite safely, but this is yet to be announced.
Q: Can you explain more about the Nitrogen injections by TEPCO?
Sir John explained that these will go on for a few more days. He continued: reactors are surrounded by containment vessels. At present, the potential for explosions is being kept as low as possible, so there is a drop in the chances of explosive activity. The Japanese are moderating the situation.
Q: Parents and children have returned to school in Toyko – should they receive iodine tablets?
Iodine should only be taken when a radioactive plume comes overhead, Sir John said, so the need to take it is probably over. Common sense tells us that there is no need for iodine at present. Sir John expressed that you shouldn’t take these tablets unless it is suggested by Japanese authorities. The UK is not recommending that people take them. David Fitton from the British Embassy in Tokyo said that the Embassy is still providing the tablets to those who would like them, but that this operation is being kept under review.
Q: Why is “new” iodine 131 not being produced in the reactors?
It just isn’t, Sir John said. Iodine is only produced when a reactor is producing electricity. When reactors are switched off, all iodine will start decaying and the amounts will naturally go down. There is no iodine in the storage ponds at all, he assured.
Q: For people who are volunteering in the quake affected area, is the 80km exclusion zone still in force?
Sir John said that the UK will be reviewing this at the next SAGE meeting. At present they are monitoring the worst case scenarios, including the impact of bad weather conditions, and calculating what the likely dosages would be. Sir John and his team will then provide advice into COBRA; it is a “work in progress”.
Q: The amounts of radiation dumped into the ocean seemed large, are there implications for seafood on a larger scale?
They do seem like large volumes but in relation to the size of the Pacific Ocean they are miniscule, said Sir John. From a practical perspective, larger scale impact is enormously unlikely because the Pacific Ocean is so large. Sir John assured that the Japanese are monitoring levels in fish and food and have banned produced from the region.
Q: Any comments on the ongoing seismic activity in Eastern Japan?
Sir John acknowledged that aftershocks are natural after such a major earthquake, but that their intensity will decay over time. Sir John stated that he is a biologist and not a geologist. The conclusion of today’s briefing was that “things are getting better” and that the Japanese are now making progress on what is a difficult problem.
Stay calm! Our thoughts, prayers, and hopes for a quick recovery are with all those who have been affected by this crisis.
Saturday, April 9, 2011
Tuesday, April 5, 2011
What Really Happened at Fukushima
This is the best account I have seen of the events at Fukushima. Sorry guys and gals, Tokyo and the rest of the world are not about to be affected. This is a "local" nuclear disaster...... This is an E-mail from the Dean of the University of Washington College of Engineering to the students - March 17
*What happened at Fukushima*
I will try to summarize the main facts. The earthquake that hit Japan was 5 times more powerful than the worst earthquake the nuclear power plant was built for (the Richter scale works logarithmically; the difference betweenthe 8.2 that the plants were built for and the 8.9 that happened is 5 times,not 0.7). So the first hooray for Japanese engineering, everything held up.
When the earthquake hit with 8.9, the nuclear reactors all went intoautomatic shutdown. Within seconds after the earthquake started, the controlrods had been inserted into the core and nuclear chain reaction of theuranium stopped. Now, the cooling system has to carry away the residual heat. The residual heat load is about 3% of the heat load under normaloperating conditions.
The earthquake destroyed the external power supply of the nuclear reactor. That is one of the most serious accidents for a nuclear power plant, and accordingly, a “plant black out” receives a lot of attention when designingbackup systems. The power is needed to keep the coolant pumps working. Sincethe power plant had been shut down, it cannot produce any electricity byitself any more. Things were going well for an hour. One set of multiple sets of emergency. Diesel power generators kicked in and provided the electricity that was needed.
Then the Tsunami came, much bigger than people had expected when building the power plant. The tsunami took out all multiple sets of backupDiesel generators. When designing a nuclear power plant, engineers follow a philosophy called“Defense of Depth”. That means that you first build everything to withstand the worst catastrophe you can imagine, and then design the plant in such away that it can still handle one system failure (that you thought could never happen) after the other. A tsunami taking out all backup power in oneswift strike is such a scenario. The last line of defense is putting everything into the third containment, that will keep everything, whateverthe mess, control rods in our out, core molten or not, inside the reactor.When the diesel generators were gone, the reactor operators switched to emergency battery power.
The batteries were designed as one of the backups to the backups, to provide power for cooling the core for 8 hours. And they did. Within the 8 hours, another power source had to be found and connected tothe power plant. The power grid was down due to the earthquake. The diesel generators were destroyed by the tsunami. So mobile diesel generators were trucked in. This is where things started to go seriously wrong. The external power generators could not be connected to the power plant (the plugs did not fit). So after the batteries ran out, the residual heat could not be carried away any more.
At this point the plant operators begin to follow emergency procedures thatare in place for a “loss of cooling event”. It is again a step along the “Depth of Defense” lines. The power to the cooling systems should never have failed completely, but it did, so they “retreat” to the next line of defense. All of this, however shocking it seems to us, is part of the day-to-day training you go through as an operator, right through to managing a core meltdown. It was at this stage that people started to talk about core meltdown. Because at the end of the day, if cooling cannot be restored, the core willeventually melt (after hours or days), and the last line of defense, thecore catcher and third containment, would come into play.
But the goal at this stage was to manage the core while it was heating up, and ensure that the first containment (the Zircaloy tubes that contains thenuclear fuel), as well as the second containment remain intact andoperational for as long as possible, to give the engineers time to fix the cooling systems. Because cooling the core is such a big deal, the reactor has a number of cooling systems, each in multiple versions (the reactor water cleanups ystem, the decay heat removal, the reactor core isolating cooling, thestandby liquid cooling system, and the emergency core cooling system). Which one failed when or did not fail is not clear at this point in time.
So imagine a pressure cooker on the stove, heat on low, but on. Theoperators use whatever cooling system capacity they have to get rid of as much heat as possible, but the pressure starts building up. The priority now is to maintain integrity of the first containment (keep temperature of the fuel rods below 2200°C), as well as the second containment, the pressure cooker. In order to maintain integrity of the pressure cooker (the second containment), the pressure has to be released from time to time. Because theability to do that in an emergency is so important, the reactor has 11 pressure release valves. The operators now started venting steam from time to time to control the pressure.
The temperature at this stage was about550°C. This is when the reports about “radiation leakage” starting coming in. I believe I explained above why venting the steam is theoretically the same as releasing radiation into the environment, but why it was and is not dangerous. The radioactive nitrogen as well as the noble gases do not pose a threat to human health. At some stage during this venting, the explosion occurred. The explosiontook place outside of the third containment (our “last line of defense”), and the reactor building. Remember that the reactor building has no function in keeping the radioactivity contained.
It is not entirely clear yet what has happened, but this is the likely scenario: The operators decided to vent the steam from the pressure vessel not directly into the environment, butinto the space between the third containment and the reactor building (to give the radioactivity in the steam more time to subside). The problem isthat at the high temperatures that the core had reached at this stage, watermolecules can “disassociate” into oxygen and hydrogen – an explosive mixture. And it did explode, outside the third containment, damaging thereactor building around. It was that sort of explosion, but inside thepressure vessel (because it was badly designed and not managed properly bythe operators) that lead to the explosion of Chernobyl. This was never a risk at Fukushima. The problem of hydrogen-oxygen formation is one of the biggies when you design a power plant (if you are not Soviet, that is), so the reactor is built and operated in a way it cannot happen inside the containment. It happened outside, which was not intended but a possible scenario and OK, because it did not pose a risk for the containment.
So the pressure was under control, as steam was vented. Now, if you keep boiling your pot, the problem is that the water level will keep falling and falling. The core is covered by several meters of water in order to allow for some time to pass (hours, days) before it gets exposed. Once the rodss tart to be exposed at the top, the exposed parts will reach the critical temperature of 2200 °C after about 45 minutes. This is when the first containment, the Zircaloy tube, would fail. And this started to happen. The cooling could not be restored before there was some (very limited, but still) damage to the casing of some of the fuel. The nuclear material itself was still intact, but the surrounding Zircaloyshell had started melting. What happened now is that some of the by products of the uranium decay – radioactive Cesium and Iodine – started to mix with the steam. The big problem, uranium, was still under control, because theuranium oxide rods were good until 3000 °C. It is confirmed that a very small amount of Cesium and Iodine was measured in the steam that wasreleased into the atmosphere.It seems this was the “go signal” for a major plan B.
The small amounts of Cesium that were measured told the operators that the first containment on one of the rods somewhere was about to give. The Plan A had been to restoreone of the regular cooling systems to the core. Why that failed is unclear. One plausible explanation is that the tsunami also took away / polluted all the clean water needed for the regular cooling systems. The water used in the cooling system is very clean, demineralized (like distilled) water. The reason to use pure water is the above mentionedactivation by the neutrons from the Uranium: Pure water does not get activated much, so stays practically radioactive-free. Dirt or salt in the water will absorb the neutrons quicker, becoming more radioactive. This has no effect whatsoever on the core – it does not care what it is cooled by. But it makes life more difficult for the operators and mechanics when theyhave to deal with activated (i..e. slightly radioactive) water.
But Plan A had failed – cooling systems down or additional clean waterunavailable – so Plan B came into effect. This is what it looks like happened: In order to prevent a core meltdown, the operators started to use sea water to cool the core. I am not quite sure if they flooded our pressure cookerwith it (the second containment), or if they flooded the third containment, immersing the pressure cooker. But that is not relevant for us. The point is that the nuclear fuel has now been cooled down. Because the chain reaction has been stopped a long time ago, there is only very little residual heat being produced now. The large amount of cooling water that has been used is sufficient to take up that heat. Because it is a lot of water,the core does not produce sufficient heat any more to produce anysignificant pressure. Also, boric acid has been added to the seawater. Boric acid is “liquid control rod”. Whatever decay is still going on, the Boronwill capture the neutrons and further speed up the cooling down of the core.The plant came close to a core meltdown. Here is the worst-case scenario that was avoided: If the seawater could not have been used for treatment, the operators would have continued to vent the water steam to avoid pressure buildup. The third containment would then have been completely sealed to allow the core meltdown to happen without releasing radioactive material. After the meltdown, there would have been a waiting period for the intermediate radioactive materials to decay inside the reactor, and all radioactive particles to settle on a surface inside the containment. The cooling system would have been restored eventually, and the molten corecooled to a manageable temperature. The containment would have been cleaned up on the inside. Then a messy job of removing the molten core from the containment would have begun, packing the (now solid again) fuel bit by bit into transportation containers to be shipped to processing plants. Depending on the damage, the block of the plant would then either be repaired or dismantled. Now, where does that leave us? My assessment:
§ The plant is safe now and will stay safe.. § Japan is looking at an INES Level 4 Accident: Nuclear accident with local consequences. That is bad for the company that owns the plant, but not for anyone else.
§ Some radiation was released when the pressure vessel was vented. All radioactive isotopes from the activated steam have gone (decayed). A very small amount of Cesium was released, as well as Iodine. If you were sitting on top of the plants’ chimney when they were venting, you should probablygive up smoking to return to your former life expectancy. The Cesium and Iodine isotopes were carried out to the sea and will never be seen again.
§ There was some limited damage to the first containment. That means that some amounts of radioactive Cesium and Iodine will also be released into the cooling water, but no Uranium or other nasty stuff (the Uranium oxide doesnot “dissolve” in the water). There are facilities for treating the cooling water inside the third containment. The radioactive Cesium and Iodine willbe removed there and eventually stored as radioactive waste in terminal storage.
§ The seawater used as cooling water will be activated to some degree. Because the control rods are fully inserted, the Uranium chain reaction is not happening. That means the “main” nuclear reaction is not happening, thus not contributing to the activation. The intermediate radioactive materials(Cesium and Iodine) are also almost gone at this stage, because the Uranium decay was stopped a long time ago. This further reduces the activation. The bottom line is that there will be some low level of activation of the seawater, which will also be removed by the treatment facilities.
§ The seawater will then be replaced over time with the “normal” coolingwater
§ The reactor core will then be dismantled and transported to a processingfacility, just like during a regular fuel change.
§ Fuel rods and the entire plant will be checked for potential damage. This will take about 4-5 years.
§ The safety systems on all Japanese plants will be upgraded to withstand a 9.0 earthquake and tsunami (or worse)
§ (Updated) I believe the most significant problem will be a prolonged power shortage. 11 of Japan’s 55 nuclear reactors in different plants wereshut down and will have to be inspected, directly reducing the nation’snuclear power generating capacity by 20%, with nuclear power accounting forabout 30% of the national total power generation capacity.. I have not looked into possible consequences for other nuclear plants not directly affected. This will probably be covered by running gas power plants that are usually only used for peak loads to cover some of the base load as well. I am not familiar with Japan’s energy supply chain for oil, gas and coal, and what damage the harbors, refinery, storage and transportation networks have suffered, as well as damage to the national distribution grid. All of thatwill increase your electricity bill, as well as lead to power shortages during peak demand and reconstruction efforts, in Japan.
§ This all is only part of a much bigger picture. Emergency response has to deal with shelter, drinking water, food and medical care, transportation and communication infrastructure, as well as electricity supply. In a world of lean supply chains, we are looking at some major challenges in all of these areas.
" Thank you.
*What happened at Fukushima*
I will try to summarize the main facts. The earthquake that hit Japan was 5 times more powerful than the worst earthquake the nuclear power plant was built for (the Richter scale works logarithmically; the difference betweenthe 8.2 that the plants were built for and the 8.9 that happened is 5 times,not 0.7). So the first hooray for Japanese engineering, everything held up.
When the earthquake hit with 8.9, the nuclear reactors all went intoautomatic shutdown. Within seconds after the earthquake started, the controlrods had been inserted into the core and nuclear chain reaction of theuranium stopped. Now, the cooling system has to carry away the residual heat. The residual heat load is about 3% of the heat load under normaloperating conditions.
The earthquake destroyed the external power supply of the nuclear reactor. That is one of the most serious accidents for a nuclear power plant, and accordingly, a “plant black out” receives a lot of attention when designingbackup systems. The power is needed to keep the coolant pumps working. Sincethe power plant had been shut down, it cannot produce any electricity byitself any more. Things were going well for an hour. One set of multiple sets of emergency. Diesel power generators kicked in and provided the electricity that was needed.
Then the Tsunami came, much bigger than people had expected when building the power plant. The tsunami took out all multiple sets of backupDiesel generators. When designing a nuclear power plant, engineers follow a philosophy called“Defense of Depth”. That means that you first build everything to withstand the worst catastrophe you can imagine, and then design the plant in such away that it can still handle one system failure (that you thought could never happen) after the other. A tsunami taking out all backup power in oneswift strike is such a scenario. The last line of defense is putting everything into the third containment, that will keep everything, whateverthe mess, control rods in our out, core molten or not, inside the reactor.When the diesel generators were gone, the reactor operators switched to emergency battery power.
The batteries were designed as one of the backups to the backups, to provide power for cooling the core for 8 hours. And they did. Within the 8 hours, another power source had to be found and connected tothe power plant. The power grid was down due to the earthquake. The diesel generators were destroyed by the tsunami. So mobile diesel generators were trucked in. This is where things started to go seriously wrong. The external power generators could not be connected to the power plant (the plugs did not fit). So after the batteries ran out, the residual heat could not be carried away any more.
At this point the plant operators begin to follow emergency procedures thatare in place for a “loss of cooling event”. It is again a step along the “Depth of Defense” lines. The power to the cooling systems should never have failed completely, but it did, so they “retreat” to the next line of defense. All of this, however shocking it seems to us, is part of the day-to-day training you go through as an operator, right through to managing a core meltdown. It was at this stage that people started to talk about core meltdown. Because at the end of the day, if cooling cannot be restored, the core willeventually melt (after hours or days), and the last line of defense, thecore catcher and third containment, would come into play.
But the goal at this stage was to manage the core while it was heating up, and ensure that the first containment (the Zircaloy tubes that contains thenuclear fuel), as well as the second containment remain intact andoperational for as long as possible, to give the engineers time to fix the cooling systems. Because cooling the core is such a big deal, the reactor has a number of cooling systems, each in multiple versions (the reactor water cleanups ystem, the decay heat removal, the reactor core isolating cooling, thestandby liquid cooling system, and the emergency core cooling system). Which one failed when or did not fail is not clear at this point in time.
So imagine a pressure cooker on the stove, heat on low, but on. Theoperators use whatever cooling system capacity they have to get rid of as much heat as possible, but the pressure starts building up. The priority now is to maintain integrity of the first containment (keep temperature of the fuel rods below 2200°C), as well as the second containment, the pressure cooker. In order to maintain integrity of the pressure cooker (the second containment), the pressure has to be released from time to time. Because theability to do that in an emergency is so important, the reactor has 11 pressure release valves. The operators now started venting steam from time to time to control the pressure.
The temperature at this stage was about550°C. This is when the reports about “radiation leakage” starting coming in. I believe I explained above why venting the steam is theoretically the same as releasing radiation into the environment, but why it was and is not dangerous. The radioactive nitrogen as well as the noble gases do not pose a threat to human health. At some stage during this venting, the explosion occurred. The explosiontook place outside of the third containment (our “last line of defense”), and the reactor building. Remember that the reactor building has no function in keeping the radioactivity contained.
It is not entirely clear yet what has happened, but this is the likely scenario: The operators decided to vent the steam from the pressure vessel not directly into the environment, butinto the space between the third containment and the reactor building (to give the radioactivity in the steam more time to subside). The problem isthat at the high temperatures that the core had reached at this stage, watermolecules can “disassociate” into oxygen and hydrogen – an explosive mixture. And it did explode, outside the third containment, damaging thereactor building around. It was that sort of explosion, but inside thepressure vessel (because it was badly designed and not managed properly bythe operators) that lead to the explosion of Chernobyl. This was never a risk at Fukushima. The problem of hydrogen-oxygen formation is one of the biggies when you design a power plant (if you are not Soviet, that is), so the reactor is built and operated in a way it cannot happen inside the containment. It happened outside, which was not intended but a possible scenario and OK, because it did not pose a risk for the containment.
So the pressure was under control, as steam was vented. Now, if you keep boiling your pot, the problem is that the water level will keep falling and falling. The core is covered by several meters of water in order to allow for some time to pass (hours, days) before it gets exposed. Once the rodss tart to be exposed at the top, the exposed parts will reach the critical temperature of 2200 °C after about 45 minutes. This is when the first containment, the Zircaloy tube, would fail. And this started to happen. The cooling could not be restored before there was some (very limited, but still) damage to the casing of some of the fuel. The nuclear material itself was still intact, but the surrounding Zircaloyshell had started melting. What happened now is that some of the by products of the uranium decay – radioactive Cesium and Iodine – started to mix with the steam. The big problem, uranium, was still under control, because theuranium oxide rods were good until 3000 °C. It is confirmed that a very small amount of Cesium and Iodine was measured in the steam that wasreleased into the atmosphere.It seems this was the “go signal” for a major plan B.
The small amounts of Cesium that were measured told the operators that the first containment on one of the rods somewhere was about to give. The Plan A had been to restoreone of the regular cooling systems to the core. Why that failed is unclear. One plausible explanation is that the tsunami also took away / polluted all the clean water needed for the regular cooling systems. The water used in the cooling system is very clean, demineralized (like distilled) water. The reason to use pure water is the above mentionedactivation by the neutrons from the Uranium: Pure water does not get activated much, so stays practically radioactive-free. Dirt or salt in the water will absorb the neutrons quicker, becoming more radioactive. This has no effect whatsoever on the core – it does not care what it is cooled by. But it makes life more difficult for the operators and mechanics when theyhave to deal with activated (i..e. slightly radioactive) water.
But Plan A had failed – cooling systems down or additional clean waterunavailable – so Plan B came into effect. This is what it looks like happened: In order to prevent a core meltdown, the operators started to use sea water to cool the core. I am not quite sure if they flooded our pressure cookerwith it (the second containment), or if they flooded the third containment, immersing the pressure cooker. But that is not relevant for us. The point is that the nuclear fuel has now been cooled down. Because the chain reaction has been stopped a long time ago, there is only very little residual heat being produced now. The large amount of cooling water that has been used is sufficient to take up that heat. Because it is a lot of water,the core does not produce sufficient heat any more to produce anysignificant pressure. Also, boric acid has been added to the seawater. Boric acid is “liquid control rod”. Whatever decay is still going on, the Boronwill capture the neutrons and further speed up the cooling down of the core.The plant came close to a core meltdown. Here is the worst-case scenario that was avoided: If the seawater could not have been used for treatment, the operators would have continued to vent the water steam to avoid pressure buildup. The third containment would then have been completely sealed to allow the core meltdown to happen without releasing radioactive material. After the meltdown, there would have been a waiting period for the intermediate radioactive materials to decay inside the reactor, and all radioactive particles to settle on a surface inside the containment. The cooling system would have been restored eventually, and the molten corecooled to a manageable temperature. The containment would have been cleaned up on the inside. Then a messy job of removing the molten core from the containment would have begun, packing the (now solid again) fuel bit by bit into transportation containers to be shipped to processing plants. Depending on the damage, the block of the plant would then either be repaired or dismantled. Now, where does that leave us? My assessment:
§ The plant is safe now and will stay safe.. § Japan is looking at an INES Level 4 Accident: Nuclear accident with local consequences. That is bad for the company that owns the plant, but not for anyone else.
§ Some radiation was released when the pressure vessel was vented. All radioactive isotopes from the activated steam have gone (decayed). A very small amount of Cesium was released, as well as Iodine. If you were sitting on top of the plants’ chimney when they were venting, you should probablygive up smoking to return to your former life expectancy. The Cesium and Iodine isotopes were carried out to the sea and will never be seen again.
§ There was some limited damage to the first containment. That means that some amounts of radioactive Cesium and Iodine will also be released into the cooling water, but no Uranium or other nasty stuff (the Uranium oxide doesnot “dissolve” in the water). There are facilities for treating the cooling water inside the third containment. The radioactive Cesium and Iodine willbe removed there and eventually stored as radioactive waste in terminal storage.
§ The seawater used as cooling water will be activated to some degree. Because the control rods are fully inserted, the Uranium chain reaction is not happening. That means the “main” nuclear reaction is not happening, thus not contributing to the activation. The intermediate radioactive materials(Cesium and Iodine) are also almost gone at this stage, because the Uranium decay was stopped a long time ago. This further reduces the activation. The bottom line is that there will be some low level of activation of the seawater, which will also be removed by the treatment facilities.
§ The seawater will then be replaced over time with the “normal” coolingwater
§ The reactor core will then be dismantled and transported to a processingfacility, just like during a regular fuel change.
§ Fuel rods and the entire plant will be checked for potential damage. This will take about 4-5 years.
§ The safety systems on all Japanese plants will be upgraded to withstand a 9.0 earthquake and tsunami (or worse)
§ (Updated) I believe the most significant problem will be a prolonged power shortage. 11 of Japan’s 55 nuclear reactors in different plants wereshut down and will have to be inspected, directly reducing the nation’snuclear power generating capacity by 20%, with nuclear power accounting forabout 30% of the national total power generation capacity.. I have not looked into possible consequences for other nuclear plants not directly affected. This will probably be covered by running gas power plants that are usually only used for peak loads to cover some of the base load as well. I am not familiar with Japan’s energy supply chain for oil, gas and coal, and what damage the harbors, refinery, storage and transportation networks have suffered, as well as damage to the national distribution grid. All of thatwill increase your electricity bill, as well as lead to power shortages during peak demand and reconstruction efforts, in Japan.
§ This all is only part of a much bigger picture. Emergency response has to deal with shelter, drinking water, food and medical care, transportation and communication infrastructure, as well as electricity supply. In a world of lean supply chains, we are looking at some major challenges in all of these areas.
" Thank you.
Subscribe to:
Posts (Atom)