Something that might be interesting to someone, hopefully
Hello, my lovelies. Although I have been rather quiet on the whole deal in Japan because I didn't feel like I had anything new to say, well, I have something new to say.
As some of y'all are aware, my father works at a nuclear power plant. It's in southern Georgia (yeah, don't ask how we still manage to live in central Alabama), and is technically a project manager for the plant, not actually a nuclear engineer. Now, obviously, the power plant explosion in Japan is high on the topics of conversation around his workplace. Since he knows that I think his work is really cool and I like hearing about things, he forwarded me and all of his colleagues an email with two highly informative updates on what exactly happened at Fukushima-Daiichi. I'm sure some of y'all already know what's going on, since y'all are more proactive in looking up what's going on in the world than me, but if you're interested in a long, informative update from people in the business, I'm copying it in here after the cut as well as copying in the text from a PDF with less length, but equal information.
Just doin' what I can to keep my friends informed.
The email part
Since a lot of new information has become available since my earlier email this morning, I thought I would give you a quick update on a few things.
First of all, fortunately conditions have improved at Fukushima-Daiichi unit 2 relative to what was reported this morning. This morning there were reports of Unit 2 seawater injection (like Units 1 & 3), but that turned out not to be correct. TEPCO, using the Reactor Core Isolation Cooling (RCIC) System has been able so far to maintain vessel water levels approximately 3 meters above the core. There are no reports of core damage, so hopefully Unit 2 will not follow the Unit 1 and Unit 2 into core damage and borated seawater injection situations. Other than this, everything I wrote about this morning has held through the day.
It is unknown to me why the Unit 3 RCIC system was not able to keep the Unit 3 core covered. It started, but failed after running for several hours. Once that injection stopped the core uncovered for approximately 3 meters and was severely damaged. This loss of the RCIC resulted in the current Unit 3 seawater injection mess. The good news is that there has been no hydrogen explosion in the Unit 3 reactor building like happened in Unit 1. TEPCO seems to be safely venting the hydrogen from the Unit 3 primary containment such that explosive concentrations and ignition have not occurred. Given that so much time has now past, it would seem to me that we are past the period of peak explosion risk. But with hydrogen gas, almost anything could happen at any time. But if it did, the forces would should be up and away from the lower hardened primary containment structure within the reactor building secondary containment.
There still is no heat rejection from the pressure suppression pools at any of the reactors so temperatures and pressures are rising and venting is needed. The tsunami destroyed the service water cooling systems. TEPCO is working hard to set up temporary RHR heat exchangers to cool the pools before they get too hot or the seawater levels in the basement areas rise to unacceptable levels.
At Units 1 and 3, I have confirmed that borated seawater is being injected into the depressurized cores with high pressure fire engine pumps. Both Unit 1 and Unit 3 primary coolant systems are now depressurized at 35-50 psig. Core cooling is with the relatively cold injected borated seawater, but the flooded wet and dry wells are filling and this mode cannot be sustained indefinitely without overflows. So within the next day, TEPCO will need to get some decay heat removal temporary heat exchangers operating to cool the wet well, Then they can go into a stable recirculation mode. Once closed recirculation can be achieved the addition of new flooding seawater can be minimized. But water injection/recirculation will likely continue somewhat like this for weeks.
It is actually very similar to how we cooled down the damaged/melted Three Mile Island Unit 2 core using the TMI main coolant pumps and steam generators. Of course Fukushima is a BWR and different, but the principle is the same. At TMI this mode continued for several months while core heat decayed. So much of this is like reliving Three Mile Island all over again.
From various sources I have gathered more information on what actually happened. As often happens, early information can be incorrect, but I think these are correct.
It seems that all the reactors withstood the earthquake ground motion OK. We do not have a comparison of actual versus design basis accelerations, but even though the motion was probably over the design basis, most safety systems seemed to be functional until the tsunami hit. The tsunami was the big problem.
It seems that Fukushima design basis tsunami was 6.5 meters, but the actual tsunami was in the 7-8 meter range. These waves washed the diesel fuel system away, submerged the switchyard and destroyed most of the switchgear. This massive damage to the electrical system prevented rapid hookup of auxiliary diesel generators that were relatively quickly brought on site. So only the turbine driven battery controlled RCIC was available to inject water into the reactor vessel until AC power was restored to the HPCI.
There is no information about the Unit 1 spent fuel pool situation. By now I am sure that TEPCO has the ability to pump water into the pool to maintain water levels. A small fire hose is all that is needed. There is no information available on debris from the explosion or anything else in the pool that is now completely exposed to the environment. Unless heavy debris fell into the pool and damaged spent fuel, this is not a big issue as long as they can keep pool water levels stable, which they should. Given the radiological releases from the primary containment pressure venting, the spent fuel pool releases are negligible.
Neither is there any information on the spent fuel dry storage cask modules that are at the Fukushima site. The Fukushima Independent Spent Fuel Storage Facility (ISFSF) is in the back of the plant site away from the ocean, so it is hard to tell if it was flooded or not. I suspect that wave water got there, but if it did it was a comparatively nothing event since these are passive cans. I believe there is ~100MTU of spent fuel in their ISFSI. But just being there is an issue in itself. Technically it is better there than in the Unit 1 pool without a roof.
In summary I think the worse is over technically. So much of this is like my Three Mile Island memories. The news on the TV and main internet sites is two days late and way sensational. The technical challenges are great, but the political/public challenges will be greater. The public relations fallout is just starting. As time goes by with reporting on the fission product venting and personnel contamination events, the coverage will likely become more and more sensational. This is just like what happened at Three Mile Island. It always seems to take the two days for information to be transmitted, digested and disseminated. Of course the press love the words “nuclear catastrophe” and “nuclear disaster”. I had one reporter ask me when the radiation reaches California will California have to be evacuated? Absolutely crazy, but all this is just starting as the press loves to hear the left wing anti-nuclear crowd perspective on the TV shows and in the newspapers. The worse was tonight on NBC that had pictures of Hiroshima on next to Fukushima. The press reporting will likely go in waves as they learn new things. Once the plants start to stabilize (which they are), reporting will shift to offsite radioactive release reporting. Once that attenuates, they will shift to reports of environmental contamination, e.g. iodine in children’s milk. They will drag out cancer statistics and lots of sad cases and testimonials. I expect it will be a feeding frenzy for a month or so until they become bored and find something new.
Enough for now.
Lake
The PDF part
American Nuclear Society Backgrounder:
Japanese Earthquake/Tsunami; Problems with Nuclear Reactors
3/12/2011 5:22 PM EST
To begin, a sense of perspective is needed… right now, the Japanese earthquake/tsunami is clearly a catastrophe; the situation at impacted nuclear reactors is, in the words of IAEA, an "Accident with Local Consequences.
The Japanese earthquake and tsunami are natural catastrophes of historic proportions. The death toll is likely to be in the thousands. While the information is still not complete at this time, the tragic loss of life and destruction caused by the earthquake and tsunami will likely dwarf the damage caused by the problems associated with the impacted Japanese nuclear plants.
What happened?
Recognizing that information is still not complete due to the destruction of the communication infrastructure, producing reports that are conflicting, here is our best understanding of the sequence of events at the Fukushima I‐1 power station.
ANS has reached out to The Atomic Energy Society of Japan (AESJ) to offer technical assistance.
ANS has established an incident communications response team.
This team has compiling relevant news reports and other publicly available information on the ANS blog, which can be found at ansnuclearcafe.org.
The team is also fielding media inquiries and providing reporters with background information and technical perspective as the events unfold.
Finally, the ANS is collecting information from publicly available sources, our sources in government agencies, and our sources on the ground in Japan, to better understand the extent and impact of the incident.
As some of y'all are aware, my father works at a nuclear power plant. It's in southern Georgia (yeah, don't ask how we still manage to live in central Alabama), and is technically a project manager for the plant, not actually a nuclear engineer. Now, obviously, the power plant explosion in Japan is high on the topics of conversation around his workplace. Since he knows that I think his work is really cool and I like hearing about things, he forwarded me and all of his colleagues an email with two highly informative updates on what exactly happened at Fukushima-Daiichi. I'm sure some of y'all already know what's going on, since y'all are more proactive in looking up what's going on in the world than me, but if you're interested in a long, informative update from people in the business, I'm copying it in here after the cut as well as copying in the text from a PDF with less length, but equal information.
Just doin' what I can to keep my friends informed.
The email part
Since a lot of new information has become available since my earlier email this morning, I thought I would give you a quick update on a few things.
First of all, fortunately conditions have improved at Fukushima-Daiichi unit 2 relative to what was reported this morning. This morning there were reports of Unit 2 seawater injection (like Units 1 & 3), but that turned out not to be correct. TEPCO, using the Reactor Core Isolation Cooling (RCIC) System has been able so far to maintain vessel water levels approximately 3 meters above the core. There are no reports of core damage, so hopefully Unit 2 will not follow the Unit 1 and Unit 2 into core damage and borated seawater injection situations. Other than this, everything I wrote about this morning has held through the day.
It is unknown to me why the Unit 3 RCIC system was not able to keep the Unit 3 core covered. It started, but failed after running for several hours. Once that injection stopped the core uncovered for approximately 3 meters and was severely damaged. This loss of the RCIC resulted in the current Unit 3 seawater injection mess. The good news is that there has been no hydrogen explosion in the Unit 3 reactor building like happened in Unit 1. TEPCO seems to be safely venting the hydrogen from the Unit 3 primary containment such that explosive concentrations and ignition have not occurred. Given that so much time has now past, it would seem to me that we are past the period of peak explosion risk. But with hydrogen gas, almost anything could happen at any time. But if it did, the forces would should be up and away from the lower hardened primary containment structure within the reactor building secondary containment.
There still is no heat rejection from the pressure suppression pools at any of the reactors so temperatures and pressures are rising and venting is needed. The tsunami destroyed the service water cooling systems. TEPCO is working hard to set up temporary RHR heat exchangers to cool the pools before they get too hot or the seawater levels in the basement areas rise to unacceptable levels.
At Units 1 and 3, I have confirmed that borated seawater is being injected into the depressurized cores with high pressure fire engine pumps. Both Unit 1 and Unit 3 primary coolant systems are now depressurized at 35-50 psig. Core cooling is with the relatively cold injected borated seawater, but the flooded wet and dry wells are filling and this mode cannot be sustained indefinitely without overflows. So within the next day, TEPCO will need to get some decay heat removal temporary heat exchangers operating to cool the wet well, Then they can go into a stable recirculation mode. Once closed recirculation can be achieved the addition of new flooding seawater can be minimized. But water injection/recirculation will likely continue somewhat like this for weeks.
It is actually very similar to how we cooled down the damaged/melted Three Mile Island Unit 2 core using the TMI main coolant pumps and steam generators. Of course Fukushima is a BWR and different, but the principle is the same. At TMI this mode continued for several months while core heat decayed. So much of this is like reliving Three Mile Island all over again.
From various sources I have gathered more information on what actually happened. As often happens, early information can be incorrect, but I think these are correct.
It seems that all the reactors withstood the earthquake ground motion OK. We do not have a comparison of actual versus design basis accelerations, but even though the motion was probably over the design basis, most safety systems seemed to be functional until the tsunami hit. The tsunami was the big problem.
It seems that Fukushima design basis tsunami was 6.5 meters, but the actual tsunami was in the 7-8 meter range. These waves washed the diesel fuel system away, submerged the switchyard and destroyed most of the switchgear. This massive damage to the electrical system prevented rapid hookup of auxiliary diesel generators that were relatively quickly brought on site. So only the turbine driven battery controlled RCIC was available to inject water into the reactor vessel until AC power was restored to the HPCI.
There is no information about the Unit 1 spent fuel pool situation. By now I am sure that TEPCO has the ability to pump water into the pool to maintain water levels. A small fire hose is all that is needed. There is no information available on debris from the explosion or anything else in the pool that is now completely exposed to the environment. Unless heavy debris fell into the pool and damaged spent fuel, this is not a big issue as long as they can keep pool water levels stable, which they should. Given the radiological releases from the primary containment pressure venting, the spent fuel pool releases are negligible.
Neither is there any information on the spent fuel dry storage cask modules that are at the Fukushima site. The Fukushima Independent Spent Fuel Storage Facility (ISFSF) is in the back of the plant site away from the ocean, so it is hard to tell if it was flooded or not. I suspect that wave water got there, but if it did it was a comparatively nothing event since these are passive cans. I believe there is ~100MTU of spent fuel in their ISFSI. But just being there is an issue in itself. Technically it is better there than in the Unit 1 pool without a roof.
In summary I think the worse is over technically. So much of this is like my Three Mile Island memories. The news on the TV and main internet sites is two days late and way sensational. The technical challenges are great, but the political/public challenges will be greater. The public relations fallout is just starting. As time goes by with reporting on the fission product venting and personnel contamination events, the coverage will likely become more and more sensational. This is just like what happened at Three Mile Island. It always seems to take the two days for information to be transmitted, digested and disseminated. Of course the press love the words “nuclear catastrophe” and “nuclear disaster”. I had one reporter ask me when the radiation reaches California will California have to be evacuated? Absolutely crazy, but all this is just starting as the press loves to hear the left wing anti-nuclear crowd perspective on the TV shows and in the newspapers. The worse was tonight on NBC that had pictures of Hiroshima on next to Fukushima. The press reporting will likely go in waves as they learn new things. Once the plants start to stabilize (which they are), reporting will shift to offsite radioactive release reporting. Once that attenuates, they will shift to reports of environmental contamination, e.g. iodine in children’s milk. They will drag out cancer statistics and lots of sad cases and testimonials. I expect it will be a feeding frenzy for a month or so until they become bored and find something new.
Enough for now.
Lake
The PDF part
American Nuclear Society Backgrounder:
Japanese Earthquake/Tsunami; Problems with Nuclear Reactors
3/12/2011 5:22 PM EST
To begin, a sense of perspective is needed… right now, the Japanese earthquake/tsunami is clearly a catastrophe; the situation at impacted nuclear reactors is, in the words of IAEA, an "Accident with Local Consequences.
The Japanese earthquake and tsunami are natural catastrophes of historic proportions. The death toll is likely to be in the thousands. While the information is still not complete at this time, the tragic loss of life and destruction caused by the earthquake and tsunami will likely dwarf the damage caused by the problems associated with the impacted Japanese nuclear plants.
What happened?
Recognizing that information is still not complete due to the destruction of the communication infrastructure, producing reports that are conflicting, here is our best understanding of the sequence of events at the Fukushima I‐1 power station.
- The plant was immediately shut down (scrammed) when the earthquake first hit. The automatic power system worked.
- All external power to the station was lost when the sea water swept away the power lines.
- Diesel generators started to provide backup electrical power to the plant’s backup cooling system. The backup worked.
- The diesel generators ceased functioning after approximately one hour due to tsunami induced damage, reportedly to their fuel supply.
- An Isolation condenser was used to remove the decay heat from the shutdown reactor.
- Apparently the plant then experienced a small loss of coolant from the reactor.
- Reactor Core Isolation Cooling (RCIC) pumps, which operate on steam from the reactor, were used to replace reactor core water inventory, however, the battery‐supplied control valves lost DC power after the prolonged use.
- DC power from batteries was consumed after approximately 8 hours.
- At that point, the plant experienced a complete blackout (no electric power at all).
- Hours passed as primary water inventory was lost and core degradation occurred (through some combination of zirconium oxidation and clad failure).
- Portable diesel generators were delivered to the plant site.
- AC power was restored allowing for a different backup pumping system to replace inventory in reactor pressure vessel (RPV).
- Pressure in the containment drywell rose as wetwell became hotter.
- The Drywell containment was vented to outside reactor building which surrounds the containment.
- Hydrogen produced from zirconium oxidation was vented from the containment into the reactorbuilding.
- Hydrogen in reactor building exploded causing it to collapse around the containment.
- The containment around the reactor and RPV were reported to be intact.
- The decision was made to inject seawater into the RPV to continue to the cooling process, another backup system that was designed into the plant from inception.
- Radioactivity releases from operator initiated venting appear to be decreasing.
- While there are risks associated with operating nuclear plants and other industrial facilities, the chances of an adverse event similar to what happened in Japan occurring in the US is small.
- Since September 11, 2001, additional safeguards and training have been put in place at US nuclear reactors which allow plant operators to cool the reactor core during an extended power outage and/or failure of backup generators - “blackout conditions.”
- Not necessarily. Nuclear reactors are built with redundant safety systems. Even if the fuel in the reactor melts, the reactor's containment systems are designed to prevent the spread of radioactivity into the environment. Should an event like this occur, containing the radioactive materials could actually be considered a "success" given the scale of this natural disaster that had not been considered in the original design. The nuclear power industry will learn from this event, and redesign our facilities as needed to make them safer in the future.
ANS has reached out to The Atomic Energy Society of Japan (AESJ) to offer technical assistance.
ANS has established an incident communications response team.
This team has compiling relevant news reports and other publicly available information on the ANS blog, which can be found at ansnuclearcafe.org.
The team is also fielding media inquiries and providing reporters with background information and technical perspective as the events unfold.
Finally, the ANS is collecting information from publicly available sources, our sources in government agencies, and our sources on the ground in Japan, to better understand the extent and impact of the incident.