About 20% of United States’ and 12% of Canadian electrical generation comes from nuclear power plants. Nuclear plants can operate a long time between refuelings – 500 days is a typical quoted figure, and some plants (Brunswick 1 and Pickering 7) are notable for having gone more than 700 days between refuelings.
This statement needs correcting. The above mentioned units ran for a long time between OUTAGES. The assumption that an outage equals refuelling is wrong. The Canadian nukes are called CANDU reactors. Thier big point is On-power refuelling. They can and must change out fuel bundles daily to maintain full power output. Without this operator controlled refuelling the units would poison out within in a week.
“When the zombies take over, how long till the electricity fails?” was actually one of our Staff Reports, not one of Cecil’s columns, written by our own Una Persson, the Goddess of Coal and Other Things Related to Power Production. I’ll move this thread from the “Comments on Cecil’s Columns” forum to the “Comments on Staff Reports” forum.
So in this case they seem to be saying that Brunswick Unit 1 did go 707 days between refueling outages, whereas for Pickering 7 it refers to a run by “any type” of reactor. Since it was mentioned immmediately after speaking on refueling, and because I did not know that Pickering 7 was a CANDU reactor, I may have made an assumption for that which is unwarranted.
Your point on CANDU’s and continuous refueling is a good one as well. I was likely being US-centric from the nuclear standpoint, but this was due to me trying to limit the article to be somewhat generally readable, not trying deliberately to ignore the variety of power plants in general.
And thanks for reading and commenting! (and you’re welcome, MEBuckner!)
Yes, it was quite good. I can’t believe, though, that we had an entire column referencing Night of the Living Dead-style zombies without even one mention of 1920’s-style undeath rays. Unconscionable, I call it.
RR
My cousin, who is a nuclear engineer working in OK, once told me a story of a “hard” shutdown on a steam turbine in northern AZ about 25 years ago.
He was working in a power plant in the office on some power issues and remembered hearing a whining crutching sound when somebody came rushing into the office and said “we lost unit xxx.” He suddenly realized that the unit which gave up the ghost was suppose to be undergoing an inspection and maintenance. When he got to the unit on the floor, everybody was trying to figure out what happened. Finally there was a quick call to the control room determined that in addition to cutting the steam (per the procedure), somebody had shut down the lubrication pump within a minute of cutting power to the turbine (not to procedure). It turned out a new guy (in training; I’m not aware that he was a zombie at the time) had seen that the juice to the turbine had been turned off and the lube pumps were still running. Being decisive, the non-zombie guy shut down the lube pumps too. My cousin was stunned, especially since the indicators showed that the turbine was still spinning and asked him why he did that. The non-zombie guy was offended by the question and argued he was “showing initiative”. “Well” my cousin said, “your initiative will be rewarded.” Being a coal fired plant, he told the non-zombie guy his new job would be to turn out a dozen ash, sulpher, and mineral content reports a day (typed—remember no desktop pc’s then) involving samples of coal for the boilers for the next 12 months. (Question: did non-zombie guy become a zombie at that point?)
The non-zombie guy had powerful connections [of a sectarian nature unfortunately] within the organization, which my cousin acknowledged could be a career breaker for him, but calculated that even they couldn’t rationalize away a boner like this. As far as he could tell nobody ever question his decision front of him or via the rumor mill.
From whatever else I can remember, my cousin said it took normally about 30 minutes for the turbine to coast to a stop (is it really that long?). When the lubrication was cut however it stopped in less than three minutes and melted partially through the support mounts and destroyed most of the turbine blades and stators.
And what about decreased demand? At the very least, sudden zombification seems to predominantly occur at night, so one would expect demand to be frozen at nighttime levels. Add in power draws which require continuous human attention, zombie-induced damage tosome of the continually-operating draws, and Omega Man occasionally going out to turn off the lights in other buildings, and I would expect power consumption to plummet. In fact, I even wonder if it would be possible for most plants to handle a demand that low (possibly as low as a single person’s consumption). How would this change the situation?
CChronos on the correct track. The electricity system would fail almost certainly do to a failure in the transmission system from a drop in demand well before any of the power plants stopped operating. The demand would plummet, while the power plants continue to produce electricity sending tons of power through the wires with no where for it to go. This would essentially cause the grid to fail and then the power plants would automatically trip off at that point.
There is a little wiggle room in there for demand. While there are a number of other things that can go wrong most systems (control areas) of generators are controlled via a central control point (control center) and these control centers send load changing signals to the power plants.
So as long as the automatic programming at the control center is working the signals will be sent to the power plants to increase or decrease the flow of fuel into the pland and therfore the generators will meet the demand.
Gasoline can lose volatility and go “stale” after some time - the actual time depends a lot on storage conditions, temperature, etc. However, it still remains burnable for some time, it’s just not in ideal condition for doing so. I’ve personally seen 15-year old gasoline stored in a steel tank be able to start up a car, so I figure with good quality tanks and cool temperatures (and enough supply) one could likely keep home generators running. If the generator gums up, just haul it out back and unpack another one.
Remember too that I’m assuming that you only need the generators for a few years - the zombies will get you, no matter what. One say you’ll let your guard down, or get careless, or get cocky, or try “making friends” or “embracing diversity”, and then…chomp.
Well, if it happens at night then the plants are already turned down to nighttime loadings when it happens. Gas turbines can run at fairly low loads for long periods of time, and even some (but not most) coal plants can have stable operation down at 40%-50% load. I’m uncertain about long-term nuclear low-load operation.
I mean, we’re kind of talking serious hypotheticals here about how a mass zombification actually goes about. If we say at midnight the process happens, it’s possible by my research and estimates that by morning (7:00 am) several plants have fallen, or at a minimum not started load ramp up. But ones which are able to continue are already at the reduced load…I guess the actualities can be envisioned many different ways.
Eh. I’ve done worse jobs and I’m still not…oh wait, the brain eating. Yeah.
Generally you want the steam turbine to come to a stop gradually to allow it to cool down slowly and evenly without risk of warping. While this spindown process is happening you need the lubrication pumps to be flowing both for a fresh supply of oil and for cooling purposes. Some turbines have small electric motors that keep them turning for some time after shutdown, to allow the turbine to contract and shrink evenly within its housing - I think they are called “pony motors” but would need to look this up or ask…
Well, I don’t know. First, remember I said that within 4-6 hours the blackouts and brownouts would start. If we’re talking a midnight zombification, then I’m saying by 4:00 am to 6:00 am we’re seeing blackouts and brownouts. So I highly doubt the demand would change that much in that length of time to cause the “grid” to fail before “any” of the power plants stopped.
Second, the “grid” is by no means a homogeneous entity. I recommend reading the report of the Big Northeast Blackout (linked at the bottom of my article) to see some maps and examples of inter-ties and connections and controls. Some parts of it are much more able to cope with load-balancing than others. Just as all plants are quite different and would respond differently to this situation, the different components of the electrical networks would also have different levels of resposne and impact.
Third - if the plants are already running at night-time loads, why would demand change that much? Let’s see where a lot of the demand would arise: if it’s Winter time, all those people with electric heaters are still going to have their heaters running. Possibly moreso, as the zombies go through windows and leave doors open, causing the thermostats to never reach temperature. Lights (excepting streetlights) that are on will stay on (unless the zombies break them). Few appliances run at night, so no big change might be seen there. Now, the morning industrial/business ramp-up won’t happen, but then most of the power plants that are still running are going to still be at their low load values, so… The same situation could be envisioned with Summer and air conditioning loads as well. But by noon most likely so many plants are down that most portions of the grid have failed anyhow.
As I said to Chronos, we’re talking some hypothetical situations here that have a wide level of variance on them, so we can’t really say what happens.
But surely there is experiential data from someplace regarding this phenomenon? From Transylvania or someplace? Or perhaps some computer simulations based on a doctoral thesis or Pentagon Wargame scenario? I mean this is important stuff!
Una, wow, once again you have done an incredible job with a staff report. Thank you for educating the ignorant. You are so cool I may have to start an Una-appreciation thread. (And no, this is not an attempt at flirting.)
It really depends on if and how much demand decreased, because a sudden drop in demand could not be quickly met by available resources, since most coal and gas generation requires time to ramp up or down it’s production. Most system operators have complex computer models that attempt to anticipate the load changes,but drastic changes can have calamitous effects.
I agree with Una that if the zombification happened at 2 or 3 in the morning (the minimum load times for most areas) then there would probably be little demand effect, compared to other times of the day. I guess the onlypoint I was trying to make was that it is not just the abiliuty of the generators to make electricity but the ability of the zombies to consume electricity as well as the zombie world to maintain the balance between the two that would determine the fate of the system.
Way too many years ago I remember visiting a GE turbine manufacturing plant in Schenectady. I seem to remember them pointing out a turning gear or something on a large 700 MW turbine which was used to slowly rotate the turbine rotor when the generator was off the grid.
IIRC the reason for turning the rotor was that it weighed so much it would warp itself under its own weight if left in one position for too long. So I imagine that if there was a concern over a cooled turbine warping there must surely be a need to continue turning a warm one.
I’ve pretty much forgotten a lot of the rest of it since after the tour the GE rep used his liquor expense account to erase my memory.
I’ve seen and heard that explanation before, but then the turbine does stay stationary for months sometimes whilst it’s undergoing a major overhaul, routine maintenance, being rebuilt or rebladed…so I’m not certain what the difference would be necessarily. But I’m no turbine expert, so perhaps someone from that field can join in and edumacate us.
So, he tried to turn you into a mindless check-signing zombie… Oh yes, I’ve had plenty of reps try to do that to me, for one reason or another, especially when I’m in the Former East Bloc. And they won’t take “no” for an answer unless I fall on the “diabetes” excuse to stay with Diet Coke or water.
Oh yes, I’ve had plenty of reps try to do that to me, for one reason or another, especially when I’m in the Former East Bloc. And they won’t take “no” for an answer unless I fall on the “diabetes” excuse to stay with Diet Coke or water.