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

[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

 

[rbelli1]

That's 30 days normal operation. Nothing to see here. Move along. Rather conservative margins are included.

How fast could you get that to a point in an emergency where you were pretty sure it was OK to walk away from?

BoB

 

[NTL2009]

While I am sure some of this is just attention grabbing tactics, I am concerned about an event like this. Do we really have an idea just how much of the damage can be contained by switching things off, or other preparations? I'm not sure it was answered, but what about satellites?

I would think that the voltage induced in power lines and other systems could still be a very large scale problem. Not 'wipe out humanity' scale, but some very serious results, lots of equipment down for a long time, lots of rationing. Yes, that could even lead to rioting and wide scale crime.

It's a little scary just how dependant we are on our electrical and electronic systems.

 

[jim hardy]

Industry is learning as they go. This is an interesting study of a geomagnetic storm in Sweden

http://onlinelibrary.wiley.com/doi/10.1029/2004SW000123/full

it describes "Geomagnetically Induced Currents" (GIC) in the neutrals of a few hundred amps .

That storm caused equipment to disconnect but didn't wreck it. What would another Carrington event do? I don't know.

4. Analysis of the Problems in Operating the Swedish High-Voltage Power Transmission System
[18] The unusually high geomagnetic activity of 29–31 October 2003 caused a number of disturbances in the Swedish high-voltage power transmission system. Circuit breakers for several power lines and transformers were tripped by the low-set residual overcurrent relays (see Appendix A for discussion on general and system-specific features of AC power transmission that are associated with GIC-related failures in the Swedish system). More than 50% of the relay operations came from the second harmonic restrained residual overcurrent relays. In general, more than 50% of the failed objects were energized within 1 to 5 min, either by automatic or manual switching operations. However, in some cases it took 25 to 90 min to inspect the failed objects before they were re-energized.

I'm apprehensive about how a "Smartened" grid will react to space weather. The dumb one is pretty resilient.