How long can nuclear plants last without power? (CME hit)

[oquen]

Last night I watched History channel 10-hours "Doomsday 10 Ways the World will End".. the others are far out like Gamma Ray Burst, Black Holes, Rogue Planet, Killer Asteroid, Nuclear War, etc. and I can only feel entertained but when I watched the Solar Storm part. I got alarmed. This has happened before in the 1800s. We are due for another one. And when the Coronal Mass Injection hit us. All power grids will be fried including transformers that will take 2 years to build. In less than 10 months. Half the world populations would die from starvations and riots. But what concerned me the most is its mentioning that nuclear power plants need constant electrical power to cool the nuclear rods. And their backup power only lasts a week. So without power, would all nuclear rods really melt down? The series mentioned 450 nuclear plants would face meltdown. If this really occurred. Would their still be areas anywhere in the world where the radioactive clouds won't reach? (for us lucky few who would survive) This is very horrifying.. what is your take on this and what realistic things must we do to avoid such global catastrophe? Without watching the show, I couldn't have been aware of it. but why are others not seemed to be worried?

What follows is some basic about CME and the danger if in case you are not aware of it.http://www.popsci.com/science/article/2011-05/are-we-prepared-catastrophic-solar-storm

One of the biggest disasters we face would begin about 18 hours after the sun spit out a 10-billion-ton ball of plasma--something it has done before and is sure to do again. When the ball, a charged cloud of particles called a coronal mass ejection (CME), struck the Earth, electrical currents would spike through the power grid. Transformers would be destroyed. Lights would go out. Food would spoil and--since the entire transportation system would also be shut down--go unrestocked.
Within weeks, backup generators at nuclear power plants would have run down, and the electric pumps that supply water to cooling ponds, where radioactive spent fuel rods are stored, would shut off. Multiple meltdowns would ensue. "Imagine 30 Chernobyls across the U.S.," says electrical engineer John Kappenman, an expert on the grid's vulnerability to space weather.

 

[rbelli1]

It seems that these worst case scenarios only happen if everyone stands around doing nothing watching the world burn. Presumably some percentage of the population would get to work fixing the most important things like food distribution and dangerous sites like nuclear plants.

BoB

 

[oquen]

It seems that these worst case scenarios only happen if everyone stands around doing nothing watching the world burn. Presumably some percentage of the population would get to work fixing the most important things like food distribution and dangerous sites like nuclear plants.

BoB

But the show mentioned the CME can wipe out all available transformers. And it would take 2 years to build a transformer and this can only be built in Germany and South Korea so in less than 2 months all nuclear power plants are already in meltdown. The shows said even now in the United States. Delivering a transformer from Germany just took too long because it needs special transportation. And remember we won't have any oil because all the pumps won't work.. but the problem is we can't build a replacement transfomers in less than 2 months.. so all 450 nuclear power plants are in meltdown already. So what is really our backup plans available at present should a CME hit tomorrow that fry all circuits much like simultaneous EMP from all directions in all areas of the world?

 

[rbelli1]

can only be built in Germany and South Korea

Lots of people will die (including yourself) if you don't get *something* working right now. Oh they only know how to make transformers on the other side of the planet so we all die.

won't have any oil because all the pumps won't work

So the CME destroys all above ground oil too?

I'm not saying things won't be bad. Just that in an emergency people will find ways to fix or at least mitigate the worst problems. A few smoking craters will be unfortunate in cases where those efforts fail but most of the planet will still be inhabitable. Also bad for the people in various conveyances that go boom without power or electronics.

BoB

 

[oquen]

Lots of people will die (including yourself) if you don't get *something* working right now. Oh they only know how to make transformers on the other side of the planet so we all die.
So the CME destroys all above ground oil too?

I'm not saying things won't be bad. Just that in an emergency people will find ways to fix or at least mitigate the worst problems. A few smoking craters will be unfortunate in cases where those efforts fail but most of the planet will still be inhabitable. Also bad for the people in various conveyances that go boom without power or electronics.

BoB

The show mentioned all our foods were processed by electricity and in refrigerators.. so after all electrical network wiped out.. we would run out of foods in a month, then with no water and no transportation to import it (remember all airplanes have their electronics wipe out as well as all boats), then there would be mass riots where your home will be invaded by others to steal anything you have left. This will go on for months then after the 450 nuclear plants meltdown, you need to leave your home and run.. but where? This is serious. We can ignore other ways the world will end but the coronal mass injections is the most scary because it happens once in 100 years and we are long overdue so it can happen within this year or soon. Watch this so you will be aware of the gravity of the situation:

http://www.history.com/shows/doomsday-10-ways-the-world-will-end/season-1/episode-4

I need to confirm that all nuclear fuel rods need electrity to maintain? Without electricity, it can really meltdown? How true is this?

 

[Astronuc]

A CME will not necessarily result in damage to nuclear power plants, since they could isolate from the grid. One describes a loss-of-offsite-power (LOOP) or station blackout (SBO) situation. NPPs have onsite diesel generators to provide necessary power.

Since Fukushima Daiichi inundation by tsunami (and loss of EP and ECCS), the nuclear industry has had to address Beyond Design Basis Accidents (BDBA), which are now a new (extended) basis. We have an array (spectrum) of Anticipated Operational Occurrences (AOOs) and Postulated Accidents (PAs), which the plants are designed to handle, and the objective is to prevent these from becoming more severe.

While much of the economic infrastructure depends on electricity supplied from the interconnected grid, many facilities have independent and on-site generation, so not all is doom and gloom. Unfortunately, shows like the one cited sensationalize catastrophe in order to hook the audience; it is entertainment rather than education.

 

[etudiant]

A CME will not necessarily result in damage to nuclear power plants, since they could isolate from the grid. One describes a loss-of-offsite-power (LOOP) or station blackout (SBO) situation. NPPs have onsite diesel generators to provide necessary power.

Since Fukushima Daiichi inundation by tsunami (and loss of EP and ECCS), the nuclear industry has had to address Beyond Design Basis Accidents (BDBA), which are now a new (extended) basis. We have an array (spectrum) of Anticipated Operational Occurrences (AOOs) and Postulated Accidents (PAs), which the plants are designed to handle, and the objective is to prevent these from becoming more severe.

While much of the economic infrastructure depends on electricity supplied from the interconnected grid, many facilities have independent and on-site generation, so not all is doom and gloom. Unfortunately, shows like the one cited sensationalize catastrophe in order to hook the audience; it is entertainment rather than education.

While not disputing any of this, I do think we underestimate the impact of a large solar flare.
The Carrington event in 1859 induced enough power across the telegraph grid that operators could disconnect the battery and still communicate.
I don't know how well our grid today would handle that, but suspect the solid state components would prove painfully vulnerable.
Could widespread blackouts be averted in that case? I'd be skeptical, because afaik, the Carrington flare impacted the grid for many hours, rather than just producing a single surge.
A worse case scenario would include destruction of most inverters and rectifiers in our electrical infrastructure. Nuclear plants are not required to have the kind of heroic EMP shielding that Air Force One receives, so they may well be at risk much as the OP suggests.

 

[oquen]

A CME will not necessarily result in damage to nuclear power plants, since they could isolate from the grid. One describes a loss-of-offsite-power (LOOP) or station blackout (SBO) situation. NPPs have onsite diesel generators to provide necessary power.

Since Fukushima Daiichi inundation by tsunami (and loss of EP and ECCS), the nuclear industry has had to address Beyond Design Basis Accidents (BDBA), which are now a new (extended) basis. We have an array (spectrum) of Anticipated Operational Occurrences (AOOs) and Postulated Accidents (PAs), which the plants are designed to handle, and the objective is to prevent these from becoming more severe.

While much of the economic infrastructure depends on electricity supplied from the interconnected grid, many facilities have independent and on-site generation, so not all is doom and gloom. Unfortunately, shows like the one cited sensationalize catastrophe in order to hook the audience; it is entertainment rather than education.

But with all the power grids shut down from damaged transformers. There is no pump to get oil.. and no fuel for airplanes or boats to deliver them and much of the roads would be blocked by massive riots and civil unrests by starved public.. remember there is no food because no deliveries so it is difficult to deliver the oil to the 450 nuclear power plants.. Unless these plans have many tons of diesel or gas as standby?

Is there no way to create nuclear plants that don't use fuel rods that depends on water to cool them? Maybe we shouldn't have created nuclear power plants knowing major CMI that can disable power grid hits Earth once in 100 years and we are long overdue.

 

[Astronuc]

Is there no way to create nuclear plants that don't use fuel rods that depends on water to cool them?

No, the fission process produces heat, and an inherent by-product of the process is fission products, which also decay. It is the decay heat from fission products which must be removed by cooling.

I believe power relay technology is adequate to protect the grid more so than the older mechanical relays of 1800s.

 

[Hiddencamper]

In an "unmitigated" total station blackout, meaning a total loss of offsite power, no injection, no steam powered cooling pumps, nothing works, you would boil off your inventory and have core damage begin within 1-2 hours (less for BWRs, more for PWRs) for a generation 2 or 3 light water reactor. Obviously advanced passive plants like the AP1000 can go up to a week or more, and small modular reactors like NuScale should be able to stay cooled indefinitely due to their small size and low decay heat loads. Containment failure will likely happen 24-36 hours after the initiation of the event.

The reality: Nuclear plants have emergency generators. Not all equipment everywhere would be lost. There's a lot of standby equipment, there is fuel oil in tanks for strategic reserves, there are engine powered standby generators at critical installations and military bases, and nuclear power plants get priority for these resources when it is necessary to ensure core cooling, especially during the early phases of an event where there is still a lot of decay heat. At Browns Ferry in 2011 when multiple large tornados caused a loss of offsite power, one of the Browns Ferry reactors had an emergency generator fail and the military air lifted replacement parts from across the country within a couple hours to allow them to rebuild that emergency generator and get it running again. So there is history of prioritizing the restoration of power to nuclear plants.

 

[Hiddencamper]

But with all the power grids shut down from damaged transformers. There is no pump to get oil.. and no fuel for airplanes or boats to deliver them and much of the roads would be blocked by massive riots and civil unrests by starved public.. remember there is no food because no deliveries so it is difficult to deliver the oil to the 450 nuclear power plants.. Unless these plans have many tons of diesel or gas as standby?

Is there no way to create nuclear plants that don't use fuel rods that depends on water to cool them? Maybe we shouldn't have created nuclear power plants knowing major CMI that can disable power grid hits Earth once in 100 years and we are long overdue.

For above ground tanks, you only need the pressure head in the tank to get fuel oil out.

Small modular reactors like the NuScale reactor are intended to be air coolable before their water supplies are depleted. It is possible. And all nuclear plants have at least 7 days of fuel (assuming 102% output from your emergency generators). During a loss of power scenario, you don't use most of your emergency systems, so you use much less fuel than full load and will have over a week of fuel easily. Even more if the plant decides to down all but one engine and just run one at a time.

 

[oquen]

Can the temporarity fuel and generators last up to 2 years? remember it is said only germany and south korea can manufacture the giant transformers that can power the grid but even these plants can get out of commission sooner or later the 450 nuclear plants in the world can suffer meltdown...

 

[etudiant]

Are there not separate failure modes involved?
The transformers suffer because the swings in voltage from the flare burn out the wiring, which is very exact and very considerable in any large transformer.
The smaller stuff dies because the stray voltages that get induced damage the now universally used solid state ignitions and fuel controllers.
So there may be much more vulnerability than expected.

 

[rbelli1]

Can the temporarity fuel and generators last up to 2 years?

I pretty sure nuclear reactors can be shut down in well less than 2 years. I would assume that the on site fuel requirements allow for a graceful shutdown in emergency conditions.

BoB

 

[rbelli1]

remember it is said only germany and south korea can manufacture the giant transformers that can power the grid

I might be able to believe that only Germany and South Korea have plants set up to produce those transformers. I refuse to believe that everyone would stand around dying waiting for Germany and South Korea to produce them. Transformers are not exactly the most complex technology. Manufacturing plants in many parts of the world could be geared up for transformer production.

Also the existing transformers could be disassembled and repaired. That may not be the proper course of action if one of them dies but if the health and safety of the entire planet was in jeopardy we could make some exceptions.

BoB

 

[Astronuc]

I pretty sure nuclear reactors can be shut down in well less than 2 years. I would assume that the on site fuel requirements allow for a graceful shutdown in emergency conditions.

Shutting down a reactor can occur in seconds, but the shutdown is not the concern. Rather, removal of decay heat from the core is the main concern following shutdown, and decay heat (from decay fission products) happens at its own natural pace.

 

[jim hardy]

Has anyone ever heard a nuts and bolts explanation of how the big transformers get wrecked? Protective relays disconnect them from the long wires first thing.
Relay equipment is built to withstand surges aroiund 1.5kv, see IEEESWC.

While a Carrington like event is way more plausible than all the word's computers stopping on 1/1/2000 or 12/31/2012

i agree it's become a Tempest in the Teapot purposed to sell commercials.

 

[etudiant]

Has anyone ever heard a nuts and bolts explanation of how the big transformers get wrecked? Protective relays disconnect them from the long wires first thing.
Relay equipment is built to withstand surges aroiund 1.5kv, see IEEESWC.

While a Carrington like event is way more plausible than all the word's computers stopping on 1/1/2000 or 12/31/2012

i agree it's become a Tempest in the Teapot purposed to sell commercials.

All I know is that a relatively minor solar storm fried a good part of the Quebec Hydro system in 1989.
As a New Yorker, whose power is going to depend on Quebec Hydro even more after our Governor shuts down Indian Point, I take that seriously. I see the result, but don't have the details, although the issue afaik is that there is a hell of a lot of fine wiring inside a transformer which overheats and burns thanks to the induced currents. That stuff fries once and is beyond repair, if the pictures are any guide.
There is a separate issue of small scale ignition systems and fuel pumps losing it because of EMP, afaik there are no standards and no actual testing is done.
The USAF has a very impressive installation out at Kirtland Lake called Trestle, a wooden trellis that supports an all up B52 to allow EMP testing.
No commercial product has ever been verified similarly afaik.
So I'm skeptical about the quality of the preparations for a Carrington class event. Imho, they are about as credible as Europe's precautions in advance of another large tsunami such as the one that devastated Lisbon in 1740.

 

[oquen]

Does anyone have a list of locations of all nuclear plants worldwide? If United States is more organized, then maybe only the nuclear plants in the US and Canada would be secured in the event of a total grid wiping CMI? Imagine worldwide it's like Syria civil war in many countries with the populations no food after months of the initial CMI and massive civil unrests. In case 150 nuclear meltdown occurs elsewhere except the United States. Would radioactive clouds hit the west? For long term plan. I'm planning of moving into the safest location because it's not the question of if CMI grid killer event will hit.. but when and how soon.

 

[rootone]

Transformers and such will not be destroyed by a CME event if they are not in use at the time.
These days we should usually have advance information of a major CME occurring that might impact Earth.
So most parts of power grids could be turned off for an hour or two - freaky, but much better than a decade long reconstruction job.

 

[256bits]

Has anyone ever heard a nuts and bolts explanation of how the big transformers get wrecked? Protective relays disconnect them from the long wires first thing.
Relay equipment is built to withstand surges aroiund 1.5kv, see IEEESWC.

While a Carrington like event is way more plausible than all the word's computers stopping on 1/1/2000 or 12/31/2012

i agree it's become a Tempest in the Teapot purposed to sell commercials.

It has to do with the Earth's magnetic field and charged particles moving from pole to pole inducing an Earth current.
Northern latitude installations are more susceptible, as well as those on non conducting terrain or on watery terrain.
The Earth current appears as a slowly varying dc current that can saturate the transformer core, entering either through the long transmission line or through the grounded wye connections, though that deserves confirmation.
If tripping occurs quickly enough, the transformer can be saved, and one losses the tripping equipment only, such as what happened mainly with the Quebec incident as it was back up in 9 hours ( mostly ).

The GME outburst from the sun was only 1/10 the size of a Carrington event, and either by fluke or fancy Hydro Quebec suffered a shutdown; even while other systems in other areas across the continent were sounding alarms of system instability, they continued to function for their clients after the event passed. A larger event pushes the Earth's field close to the surface so that installations at lower and lower altitudes begin to notice greater effects.

http://www.nerc.com/files/1989-Quebec-Disturbance.pdf
Note the problem at Salem installation, on marchy land, and very far south from the Hydro Quebec.

The sensationalism aspect comes in from an angle that ALL transformers and installations in NA ( and the world ) will be rendered damaged for an excessive amount of time. I would consider that to be far from the truth.

 

[rbelli1]

removal of decay heat from the core is the main concern following shutdown,

How long would it take to render a typical reactor walk away safe from full operation? Assume back up power sources can be made operational to operate heavy equipment.

BoB

 

[mheslep]

The shutdown of the Ft Calhoun reactor in the event of a flood provides one example on an upper limit of the cooling period after shutdown: the reactor reached cold-shutdown 11 days after notice that the river would reach a threatening high level, i.e. 1 atmosphere and under 100C.

The spent fuel cooling pools at the plants are another matter.

 

[Hiddencamper]

If the fuel is in the reactor vessel, there is a period of time until you reach "loss to ambient" conditions, where decay heat can be removed through the walls of the vessel. For BWR plants this is probably on the order of weeks to a month or two. For PWR plants it will depend on a number of conditions and may be several months.

For the fuel in the spent fuel pool, the NRC studies show that 4 months ensures all BWR fuel is safe, and 11 months for PWR fuel.

 

[mheslep]

Does some kind of reactor coolant flow continue during refueling? Apparently the average US refueling time is 43 days.

 

[Astronuc]

Does some kind of reactor coolant flow continue during refueling? Apparently the average US refueling time is 43 days.

The reactor cavity is flooded, so that there is some depth of water above the core, which provides shielding to personnel on the refueling bridge. Depending on the situation, some fuel (reinserts) may be left in the core while fuel to be discharged is removed and placed in the spent fuel pool. Just after shutdown, there is a residual heat removal system that cools the fuel (removes decay heat).

Some plant may do a full core offload, so all the removed from the spent fuel pool.

 

[Hiddencamper]

As long as fuel is in the reactor you need to keep decay heat removal in service.

BWRs will use spiral refueling patterns and leave fuel in the core. So they need continuous core cooling. What I've seen, is a few days into the outage, with the reactor cavity flooded and connected to the spent fuel pool, you can shut down the residual heat removal system and use the spent fuel pool cooling pumps to cool the core and spent fuel pool.

If all fuel is removed from the core you need to maintain fuel pool cooling at all times. In all cases we never shut down decay heat removal during refueling activities other than realigning systems of tests for short periods of time (typically less than 2 hours or as allowed by the license). Loss of shutdown cooling hits a number of performance indicators and can be a precursor to an event.

43 days is a looooong time for an outage. Some plants like Clinton have done 11 day refuels. Exelon is known for 20 day or less outages. But even at 43 days you need to maintain cooling.

 

[rbelli1]

So shutting down and walking away is lengthier process than I though. Could a reactor be operated in a no load capacity just enough to keep itself in power and properly maintained?

BoB

 

[oquen]

So with all grids turned off. The CME can't damage any components? Not even the power lines cables? How long before we knew Earth would be direct hit? But all satellites would be wiped out.. so there is no communications. But it would be relieved if we at least shut down all electricity on Earth prior to the hit so the 450 power planets can still be maintained (because if there is miscommunication and all grids not turn off, then there would be no power for 2 years or 5 years or even more as the scene of Syrian civil war is duplicated in every country with the icing being the release of all radioactive clouds from 450 meltdowns.

 

[Hiddencamper]

If the CME caused the plant to trip, it will not be able to restart to operate. There are several reasons such as the following:

You don't know if the main generator is damaged in the first place from the CME.

Operating license requirements do not allow a nuclear plant to restart without at least 2 qualified and OPERABLE offsite power circuits.

Monoblock turbines (which are pretty popular now a days) cannot operate at low loads for extended periods of time and will vibrate/rub themselves to death. Turbines in general don't like extended low load operation.

The plant isn't designed for extended low power operation. Operating at low power is difficult to manage from a reactivity standpoint, as you have reduced feedback from major reactivity feedback mechanisms like voiding for BWRs. Also feed pumps will be operating at a lower point on their efficiency curve, creating seal or thrust bearing issues. Reactor coolant pumps at low speed (for BWRs) may also suffer from this.

You may not have power to even restart the plant. My BWR has to get BOP power from the grid, our emergency generators can only supply power to their dedicated bus, they cannot cross tie to the BOP busses. Some plants can cross tie, but it is unlikely they would have enough power to start a circulating water pump to get the condenser back in service.

The reactor shutdown and cooldown process takes less than 36 hours per the plant's operating license. You have to be able to go to cold shutdown (<200 degrees F) in this time. The issue is you still need to keep cooling it to keep it cold.

 

[oquen]

How strong should be a CME before it destroys satellites? Imagine an initial wave of CMI of low strength enough not to be detected.. then it destroys all satellites. When the second primary CMI wave comes after it.. how can the world communicates to shut down power grid when all satellites are dead. The History series depicts the scene where after radioactive fallout from 450 nuclear plants, then the dead satellites come falling down as meteors light up the sky. But it ends with optimistic note because 200 years later, when rain washes the radioactive fallout.. some cave hiding people can re-start our civilization (it shows skyscraper covered with green grass).

 

[mheslep]

As long as fuel is in the reactor you need to keep decay heat removal in service.

Need to ... why, after cool down? A regulatory issue? As you mention, at some point an equilibrium with ambient air is reached.

Clearly a great deal of best practice and redundancy has been put in place in US reactor design and operation for uninterrupted cooling. Nonetheless, the idea of flip-a-switch, walk away safe reactor design has a safety appeal, especially abroad, and several of the new technology reactor companies are touting the capability.

 

[oquen]

Sorry. I made a mistake.. the 200 year hiding is during nuclear holocaust (in the other series) where all the nuclear arsenals in the world is unleased.

For pure CME event. the following would be the consequence (it is shared by no less than Michio Kaku and Home land security experts in the History series).

* There will be no water to flush the toilet
* Financial and Banking system will be at standstill or collapse so you won't have money after one week
* Food would be scarce after a month
* Riots, Civil war, etc. will occur after a month
* nuclear plants meltdown will occur after 2 months
* by 10 month.. 90% of the world population will die from violence and mass starvations
* after a year.. the 10% remaining survivors will re-start civilization
* the series doesn't say nuclear clouds will circle the globe. Maybe the only area affected will be in the vicinity of the 450 nuclear plants meltdown?
Then the rest will be saved.. and majority will die off from hunger, diseases (no hospitals anywhere because no electricity)...
best investments seem to be solar panels in your roof

 

[mheslep]

...Turbines in general don't like extended low load operation...

Another point in favor of Small Modular: many small reactors on, at best RPM, or off depending on load.

 

[mheslep]

For pure CME event. the following would be the consequence (it is shared by no less than Michio Kaku and Home land security experts in the History

The former government official, Pry, is also hawking a book. His contention about EMP and solar flares are said to be wildly overblown by some, including physicist Yousaf M. Butt. With the experience of the apocalyptic world wars to draw from, the idea of 90% death of population from a solar flare is absurd.

https://warisboring.com/the-overrated-threat-from-electromagnetic-pulses-46e92c3efeb9#.k03ytzv63

best investments seem to be solar panels in your roof

If utility grade eqipment with all of its overload protection fails, PV on the roof would not be immune.

 

[rbelli1]

how can the world communicates to shut down power grid when all satellites are dead

Much of the modern modern communication infrastructure is via undersea/underground cable and fiber.

We will also see the event long before the CME strikes earth. The electromagnetic (light, RF etc) evidence will be detectable in about 8 minutes of occurrence. The CME itself travels 10s to 100s times slower.

* There will be no water to flush the toilet
* Financial and Banking system will be at standstill or collapse so you won't have money after one week
* Food would be scarce after a month
* Riots, Civil war, etc. will occur after a month
* nuclear plants meltdown will occur after 2 months
* by 10 month.. 90% of the world population will die from violence and mass starvations
* after a year.. the 10% remaining survivors will re-start civilization

I reiterate. These catastrophic occurrences only occur if everyone stares catatonically and watches the world burn.

BoB

 

[Hiddencamper]

Need to ... why, after cool down? A regulatory issue? As you mention, at some point an equilibrium with ambient air is reached.

Clearly a great deal of best practice and redundancy has been put in place in US reactor design and operation for uninterrupted cooling. Nonetheless, the idea of flip-a-switch, walk away safe reactor design has a safety appeal, especially abroad, and several of the new technology reactor companies are touting the capability.

Decay heat.

The operating license requires a decay heat removal system inservice at all times if the vessel is not flooded (except for 2 hours at a time for testing/swapping trains).

If you shut down decay heat removal, especially within the first few weeks after shutdown, a BWR will start boiling in a couple hours. That becomes an unauthorized mode change and the startup of the plant without all required systems in service.

Equilibrium may take much longer to achieve. I have not seen any study for time to equilibrium conditions for decay heat removal. It's going to be longer than the diesel generator fuel supply time. remember equilibrium is based on energy, not temperature. I can bring the reactor to cold shutdown even while it is still producing 100 million btu/hr, but the moment I shut down decay heat removal it's going to rapidly heat back up.

 

[bobkolker]

We can cobble together DC generators which can power DC moters that can turn AC alternators w.o. using transformers. This can power water delivery systems and other critical infra-structure elements. It may not be first class power, but we can get it going in fairly short order. This will buy us time to restore full AC power and grid delivery.

If we have another Carrington Event all is not lost. It is a bad hit but it is not an extinction level event either.

 

[bobkolker]

Has anyone ever heard a nuts and bolts explanation of how the big transformers get wrecked? Protective relays disconnect them from the long wires first thing.
Relay equipment is built to withstand surges aroiund 1.5kv, see IEEESWC.

While a Carrington like event is way more plausible than all the word's computers stopping on 1/1/2000 or 12/31/2012

i agree it's become a Tempest in the Teapot purposed to sell commercials.

The Cable T.V. (so-called) science programs just love to tell us the civilization will be ended by the next Carrington Event. It wont. A lot of people will probably die, but civilization will not be ended and recovery is possible by using direct current generators locally to power DC motors located at critical plants. These DC motors can turn AC alternators all without transformers.

 

[etudiant]

It would be useful to have a sober look at this risk, something not enhanced to sell a book.
As there have been such events happening in recent years as well, there have presumably been industry risk assessments.
It would be implausible that there were not after the Quebec episode.
Does anyone have a link to these studies?

 

[jim hardy]

All I know is that a relatively minor solar storm fried a good part of the Quebec Hydro system in 1989.

I'm a skeptic on that one.

I remember that day well. I was told at the time it was triggered by mis-operation of a protective relay.
That's anecdotal but compatible with the lines I've highlighted below

http://www.hydroquebec.com/learning/notions-de-base/tempete-mars-1989.html
In March 1989, Québec experienced a blackout caused by a solar storm
On March 10, a strong wind left the Sun, heading for Earth. On March 12, the first voltage fluctuations were being seen on the Hydro-Québec transmission grid. The System Control Centre was doing what it could to maintain stability. However, on March 13 at 2:44 a.m., the Earth's magnetic field was fluctuating violently. The grid's protection system was triggered, and a blackout occurred in less than a minute! The province was submerged in darkness for more than nine hours.

Hydro-Québec strengthens its grid
Shortly after this blackout, Hydro-Québec organized a task force to analyze the events and propose corrective measures. The following measures have since been applied:

• Recalibration of protection systems and raising of the trip level. This tactic has proven effective, seeing there have been very intense magnetic storms since 1989 but they have not caused any problems.
• Establishment of a real-time alert system that measures disturbances on the power grid during magnetic storms.
• Modification of power system operating procedures. In the event of a disturbance, Hydro-Québec reduces power flow on lines and direct-current interconnections, and suspends all major switching operations.
• Installation of series compensation on power lines to enhance grid stability. This measure has been very effective in mitigating the impact of magnetic storms.

Québec is not alone to suffer the effects of magnetic storms. All power transmission companies located at higher latitudes, such as Scandinavia, Alaska and Northern Russia, are vulnerable. Hydro-Québec still remains more vulnerable due to Québec's position on a large rock shield that prevents the current from flowing through the earth. The electricity then finds a less resistant path along the power lines. What's more, Hydro-Québec's grid is made up of very long transmission lines, making it even more vulnerable to the Sun's temper tantrums.

An international network
Today, there is an international network that monitors the Sun's activities through satellites and observatories. The data is then used by regional centres to predict disturbances. One of these centres, located in Ottawa, posts a "weather report" on the Internet and updates it every hour, so we're alerted ahead of time. Forewarned is forearmed!

So I'm still of the belief the Great Quebec and New York blackout happened because their protective relays were set too sensitive to ride out the solar storm .

the issue afaik is that there is a hell of a lot of fine wiring inside a transformer which overheats and burns thanks to the induced currents. That stuff fries once and is beyond repair, if the pictures are any guide.

Fine wiring in utility scale transformers ? Ever been inside one ? The wires are as big as your arm.

I never heard of any equipment being wrecked by induced current or voltage in that event. Has anyone else ?

 

[Hiddencamper]

Talking about an international network...

when a K7 or greater geomagnetic storm is coming through, we get a call from the ISO telling us to hold off on non-critical activities that affect the switchyard. It's not as limiting as a hot weather alert, but it's a notification that we might see unexpected relay actuations and for us to be ready to reset and reclose lines.

 

[256bits]

So I'm still of the belief the Great Quebec and New York blackout happened because their protective relays were set too sensitive to ride out the solar storm .

So what is the point of even using protective relays? if they aren't there to protect the system from overload.
Hydro Quebec re-assessed the data from the storm and with the realization that initial calculations were conservative, they decided the system would not be damaged beyond repair for future similar storms if they increased the trip settings.
A larger storm from what hits the Earth would trip the protective device. One can't keep on raising the trip level without consequences.

 

[jim hardy]

So what is the point of even using protective relays? if they aren't there to protect the system from overload.

Overload ≠ CME

A larger storm from what hits the Earth would trip the protective device.

As it should to protect the equipment from DC induced by the storm.

You want a system that'll disconnect from a tsunami but will ride over little ripples.

 

[mheslep]

Decay heat...

Yes, I know, which is roughly 6% of full power just after fission shut down, 1% after one hour, 0.5% at one day and so on.

it's going to be longer than the diesel generator fuel supply time

I would think the decay heat would be close to equilibrium by the time after shutdown that refueling becomes feasible, even if a decay heat cooling loop is required to run for regulatory reasons. I had thought, especially in the wake of the Fukushima accident, that the time required to reach equilibrium-to-ambient would be known for most reactors.

As the like of Nuscale SMRs come closer to build out, and the new molten salt companies submit designs for acceptance, I suspect characterizing a reactor as walk-away-safe will become more prevalent, and then the same question will increasingly be asked about existing large light water reactors, at least, at what point do they become so.

 

[gmax137]

I would think the decay heat would be close to equilibrium by the time after shutdown that refueling becomes feasible

Sorry, no, it is not close to equilibrium, unless you allow boiling in the pot or in the pool.

Take 3.5 days after reactor shutdown; the decay heat from a 3400 MW core is nearly 15 MW (= 50 million BTU/hour). That's a lot of heat to dissipate to atmosphere; the surface area of the vessel is nowhere near enough.

 

[mheslep]

Sorry, no, it is not close to equilibrium, unless you allow boiling in the pot or in the pool.

'It' being the being the time elapsed prior to refueling?

Take 3.5 days after reactor shutdown; the decay heat from a 3400 MW core is nearly 15 MW (= 50 million BTU/hour). That's a lot of heat to dissipate to atmosphere; the surface area of the vessel is nowhere near enough.

Right, at a day or several days. The wiki 100 day decay heat curve has 0.4% of full power at one day, 0.2% at a week, so 7 MW/3400MW at a week, etc.

Ball park RPV, loss to ambient calculation:
surface area, h=12M, D=5.5M, A= 250 M^2, 0.25M thick steel (k=54W/m-K), assume delta T to ambient = ~50C, then heat flow out of the RPV, is
Q = dT / Rth = 50/(.25/54*250) = 2.7 MW into containment air. That Q could be improved (fins), though I imagine heating up containment is not acceptable either.

 

[Hiddencamper]

There is mirror insulation around the RPV or some other substantial insulation.

The GE heat balance calc assumes at full power you lose 1.1 MW to drywell atmosphere. That's at 1025 psig in the vessel (saturation temp), and I think 120 degF in the drywell.

Typically the acceptable temperature limit is 330 degF in drywell during accident conditions (either the limit for ADS operation or for equipment qualification). You enter the emergency operating procedures at 150 degF or high drywell pressure (<= 2 psig typically)

You'll need to break containment integrity to do a loss to ambient setup. Only BWR 6 plants have containment ventilation systems.

 

[gmax137]

... = 2.7 MW into containment air ...

This neglects the convention heat transfer coefficient at the vessel outer surface, which will be more limiting than the conduction resistance through the vessel wall. Pardon my imperial units, but I get about 40 Btu/hr-ft2-F for the conduction; the convection is probably around 4 Btu/hr-ft2-F (since the fans blowing air through the cavity aren't going to be powered in this event). That would reduce your heat loss to about 0.3 MW. That's more than 4 years after shutdown for a 3400 MW plant. Plus, as hiddencamper notes, the cavity is an enclosed space, not well connected to the overall containment atmosphere (so that 90F delta temperature you're using is not going to last for very long; the air is going to heat up).

All of this explains why the current designs for decay heat removal are based on boiling water (at ~ 500 gpm liquid supply) or by pumping liquid through the core at 4,000 gpm and then through a heat exchanger to the river / lake / ocean heat sink.

 

[mheslep]

All of this explains why the current designs for decay heat removal are based on boiling water (at ~ 500 gpm liquid supply) or by pumping liquid through the core at 4,000 gpm and then through a heat exchanger to the river / lake / ocean heat sink.

Agreed. I was naively attempting to quickly identify some outer time limit safety via conduction cooling, to further conversation about blackout safety, though on reflection the only designed in thermal path to ambient is via the water coolant, as you say.

Nuscale promotes the notion that their 150 MWth SMR reactor design is blackout safe for decay heat from the moment the reactor stops fission. They do so via two paths: they boil away water surrounding the RPV for 30 days (it's submersed). Then, at 400 KW decay heat and below, they air cool via conduction, indefinately. I imagine the hot RPV surface generates consideral convection in the chimney shape enclosing it. Also, as their RPV is considerably smaller in volume than a typical LWR, the surface area to heat power is significantly higher.

http://www.nuscalepower.com/images/our_technology/nuscale-desalination-desal-journal.pdf