# A Tale of Two Towers

We often drive on a stretch of Minnesota State Route 10 that runs from Elk River to Big Lake and eventually to a point past Saint Cloud that takes about an hour to drive on a normal day, and we see trains. The railroad track runs along this route, and during the hour it takes to drive it, we never fail to see at least one train in operation. Usually there are two or three. Often, maybe every tenth time, one of the southeast bound trains is carrying coal; Dozens and dozens of cars loaded with coal come down this track from somewhere far away, because there is no coal anywhere near here.

The probability of seeing a train on this track is not bound to time of day or day of week. I've driven this route a couple of hundred times, at least a few times on every day of the week and at some point at all times of the day and night. I feel comfortable extending my observations of what happens in a give hour to the rest of the day, week, month, and year. I'm not sure why there would be anything other than a fairly evenly distributed schedule of trains anyway. Say they only load coal or freight or petroleum or some other product at certain times of the day. These things are being routed from and to many different locations around North America. Therefore, there can be no particular stretch of heavily used track that sees a lull or a rush hour of trains. Or, if there is such a thing happening, it is not something that I've observed. And I've been paying attention.

(As I write this from the passenger seat of our red Subaru, a train is passing just at the very beginning of this one hour stretch ... hopper cars but for grain, not for coal ... about 100 of them ... probably empty since the pike is being pulled by only two engines.)

Now, think about that for a second. If it takes me one hour to drive this stretch of Route 10, and I see two trains go by each time, then that means that a reasonable estimate of the number of trains that run on these rails per day is about fifty. If every fifth train is coal, then that means five or so of these are coal trains each day, and they are all going to one power plant. This is one of the main power plants in the region. It looks pretty clean from the outside. You don't see belching black smoke coming out of giant stacks. Nonetheless, all of that coal is converted into heat, ash, and CO2, which in turn is the most important greenhouse gas.

When I think about that, while diving by the coal plant and seeing a train coming down the tracks off in the distance, and notice the very large cinder mountain ... the only high thing around this flat place ... next to the plant, I am obviously made more viscerally aware of global warming than I otherwise might be.

There are places along this route where I can see the stacks from this coal plant. From a smaller number of places, I can see the coal plant at the same time as a small, narrow but very tall old-fashioned looking stack several miles away. This is not really a smoke stack, but rather, a different kind tower. That is the Monticello Nuclear Power Station.

Monticello is a single reactor of the same exact design as the plant at Fukushima. The Fukushima plant is famous for having three of its reactors melt down following the devastating 9.0 earthquake and ensuing tsunami.

I think its interesting that lots of people I know live within the evacuation zone of this plant, or the one other nuke plant in Minnesota, and have no idea that they do. Or, they kinda know but they don't think about it. These plants were built a long time ago and most people don't think about these things, so that's understandable, but I would think that with the disaster in Fukushima there would be at least a passing interest in knowing that the nearest major power plant to your home is a Fukushima-style reactor.

One of the reasons that the Monticello Nuclear Power Plant is not on the radar of the average Minnesotan living in the vicinity is that this particular plant has a very good safety record. There was one notable incident in which quite a bit of radioactive water was dumped into the Mississippi (in the 1980s) and one or two other problems. One incident involved the death of one of the plant workers, but this was an electrocution involving the electrical generation aspect of the plant. It could have happened at any power plant. In any event, the fact that Monticello has one of the best safety records of all the nuclear power plants in the US means that it does not get on the news too often, so it stays off the radar screen.

Another reason is that Minnesotans have a different kind of radar screen than other people do, in a sense. We are more likely to wait until something goes wrong then say something under our breath about it, than to go running around screaming and yelling about the dangers of nuclear power like other people seem to do.

A couple of weeks ago, my friend and colleague Analiese Miller and I tried to get a tour of Monticello. We were told that since 9/11, tours has been canceled. I suppose I could ask again now that Osama bin Laden has been caught. And I'm not being funny when I say that. It isn't the fact that he was caught that matters as much as what they found in his house. At least so far, we've heard of no evidence to attack US nuclear power plants. Instead, we've heard of evidence to attack US railroad tracks. And as we're driving along Route 10, and I can see the railroad tracks just off to one side of the road with the Monticello Nuclear Power Plant tower just becoming visible as I write this, I think ... maybe I shouldn't be here, this close to the tracks!

Eventually, Ana and I will do what we originally intended regarding this plant. A tour would have been the best way to do it, and I still may actually ask again, but the tour itself is not the point. What we wanted to do is two things: 1) To compare Fukushima with Monticello. Since they are the same reactor design it would be interesting to go down the list of things that went wrong at Fukushima with a nuclear engineer from Monticello and get the local take on the story. Also, we could ask about local issues that might not be a factor in Japan. Very few tsunamis make it to Monticello, Minnesota, but there are tornadoes. And cold. And, 2) To compare Monticello Nuclear Power Plant with the nearby coal plant. As I write these words, we're driving by the coal plant, and if I look over my left shoulder, I can see the skinny tower and squared off reactor building of the power plant. I find it interesting that the two plants are so close to each other. Is there a reason for that? How to the plants interact as members of the same power grid? Is the coal plant considered part of the backup generator system for the nuclear power plant? Does the coal plant turn up production during refueling at the nuclear plant? And so on and so forth.

I'm thinking we can meet the power plant experts at the Coffee Cup in Becker and talk. Maybe find a place along the road where we can get all three of us and the two plants in the same picture with the wide-angle. And, I didn't ask about getting a tour of the coal plant. Maybe that's in the cards.

Update: The NRC has just completed a report on safety at Monticello as part of a larger effort to assess safety generally at US nuclear power plants. Get your copy here. (It is a small PDF file.)

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that stack isn't a cooling tower. it's called an off-gas stack. here's a good explanation of what it does. (monticello, being a boiling water reactor, has an sjae system.)

I imagine a tour at Sherco may be easier than Monti or Prairie Island, but who knows these days. Sherco is quite large at 2400 MW while Monti is 600 MW, so I would guess Sherco could play into the redispatch with Monti refueling, but there are quite a few other area power plants (coal/natural gas/nuclear) as well as DC links to North Dakota and Manitoba to rely on. Looking at the last couple years of refueling as reported, it looks like March-June is the preferred schedule, perhaps to avoid summer peak conditions. If Manitoba is exporting hydro power at that point, there is another point for reliability during times of outage.

If as I suspect a number of transmission lines converge on the plants, then having them close together avoids building additional lines. Today folks object to transmission lines spoiling their view. If the lines were already there for one plant, the second is easier if you just put a tie line in, or some of the lines go by it. Note that in the case cited being on the river is important for both plants for make up water at least and possibly condensing water.

i assume you have seen the new power plant at St Paul.a white box with short stacks that don't seem to have anything coming out of them.

It looks pretty clean from the outside. You don't see belching black smoke coming out of giant stacks.

That stuff that you see coming from a smoke stack isn't dangerous. The black stuff is soot. It is used as black pigment, because it stays black even in heavy UV light. It is also safe for food colouring. It can help digestion in the form of carbon tablets (i.e. pellets of soot).

The white stuff is water vapour. As dangerous as clouds.

The dangerous stuff is invisible. CO2, NO2, SO2, or fine-grained ash that causes lung cancer cannot be seen.

Is the coal plant considered part of the backup generator system for the nuclear power plant?

Yes, but the power grid can bring backup power also from further away. Things could get quite messy, if there were only one backup that gets overloaded at failover and automatically shuts down to prevent its own destruction. The shutoffs then spread like wildfire, leaving wide areas without electricity. It has happened before...

By Lassi HippelÃ¤inen (not verified) on 11 Jun 2011 #permalink

i assume you have seen the new power plant at St Paul.a white box with short stacks that don't seem to have anything coming out of them.

I don't go to St Paul too often, but i was just there and I did see a big white box.

As a cub scout, many moons ago, we were given a tour of the nuclear power plant that used to operate at the north edge of Elk River (Hwy 10 & 101). They walked us through the containment vessel! I remember looking down into the pool at the fuel rods. Obviously they were not operational at the time, but still.

Those were the days. Probably about 1958.

By Keith Hammerbeck (not verified) on 12 Jun 2011 #permalink

The coal is coming from the Power River Basin in Wyoming and Montana. The BNSF ships it thru Montana and North Dakota (in all likleyhood), although northern Neb is a possible. The total business for the railroads in that area has lead to the track thru the basin going to 3 tracks at once.

Is it one of these coal plants? 25 dirtiest coal plants

It boggles me when I hear people say we are too small and insignificant to affect the climate of our planet. Two words for them: "Industrial Scale".

Hope you do get a chance to tour the nuke plant, and the coal plant too. I'd love to read that series. Do you have a journalist hat you can wear?

Passed both the nuke and the coal-fired plants many times on the way to Royalton to visit my father's family. I'm surprised the nuke hasn't been decommissioned yet.

Theilen's meat market in Pierz had kielbasa to die for, the plate-sized breakfast rolls at the Pine Edge Inn were always on my dad's agenda, and we kids thought Treasure City was a must.

Electrical power systems are such an interesting subject that it is sub speciality of electrical engineering. All I ever got was the intro course on electrical machinery.

One interesting detail of grids is that once they get big enough, any one generator has almost no effect on the grid. The limit of its impact is to alter the line frequency by very small fractions of a Hz from the nominal 60Hz. So nearby plants don't interact much more than if they were widely separated.

If I could ask a question of an engineer at a nuclear power plant it would be why you would not use the heat from the core to keep running a turbine even after the core was shut down. (The power output decays over many minutes as fission slows down. There is then a high level of power from the decay of fission products for quite a long time.) It just seems stupid for a nuclear power plant to melt down due to a lack of electricity when they had plenty of heat to generate steam to run a turbine.

Here in RI the majority of our power comes from natural gas. Even that is questionable now as it still puts out CO2 emissions and the process for extracting it is environmentally damaging.

But also in the mix is nuclear and hydro and yes coal. There are nuke plants in MA, VT, CT and NH with one of the CT plants decommissioned a couple years ago.

DSchultz : why you would not use the heat from the core to keep running a turbine even after the core was shut down

An interesting question. In fact the exact question they tried to answer in Chernobyl. Unfortunately their reactor became unstable at low levels of core activity...

By Lassi HippelÃ¤inen (not verified) on 12 Jun 2011 #permalink

why you would not use the heat from the core to keep running a turbine even after the core was shut down

Even if Fukushima Daiichi had such a system (I have no idea whether this was the case), it would have had to be properly designed and constructed to withstand a magnitude 9.0 earthquake (which we know was not true of other systems at the plant) followed by a 10-14 m tsunami (ditto) and remain operational (unlike the reactors, which should have shut down). The way things unfolded, I don't think it would have helped, and if the plant had been properly designed and built to withstand an earthquake and tsunami of this magnitude, the diesel generators they did have on hand would have done the job.

There may well be other situations where it would be useful, e.g., typhoon strikes, which while not a major concern in the Tohoku region are an issue elsewhere in Japan.

By Eric Lund (not verified) on 12 Jun 2011 #permalink

Keith, from Wikipedia:

"Elk River Station is an energy-from-waste plant operating in Elk River, Minnesota that generates 35 to 42 megawatts of electrical power.
The site was originally built as a coal and oil-fired facility in 1950, then was converted to a nuclear power plant (boiling water reactor) in 1963. The nuclear reactor was small and only operated from 1964 until 1968 before undergoing decommission and dismantlement in the following years, ending in the early 1970s.
It resumed operating on coal and oil in 1968.
In 1989, the facility was again converted, this time to use Refuse Derived Fuel or (RDF) for fuel. The RDF is made from municipal solid waste. Waste arrives from Anoka, Benton, Hennepin, Sherburne, and Stearns counties, and the ash remaining after incineration is taken to a landfill in Becker, Minnesota.
Elk River Station is operated by the Great River Energy cooperative."

Why are they so close together? That's a nearly meaningless question. Where the plant is located has little bearing on the area where it delivers power to. Take, for example, the hydroelectric dam in Greenup (actually Lloyd) Ky. that is owned by Dayton Power and Light. The local grid is AEP which owns at least one coal fired plant in the immediate vicinity. How far away is the DP&L distribution area? Is one the backup for the other? No. They both happen to be located in an area that is perfect for different ways of generating electricity; i.e. the Ohio River Valley.

why you would not use the heat from the core to keep running a turbine even after the core was shut down?

Nuclear plants do use steam from the reactor to cool the core in a loss of electrical power. In a BWR (the type Monticello is), this is typically in the form of HPCI (High Pressure Coolant Injection) and RCIC (Reactor Core Isolation Cooling). Essentially, as long as reactor pressure stays above ~150 psi, turbines that run on steam (or even high pressure water, these are sturdy turbines) can keep the core cooled. The water can be pumped just fine without electricity. However, the amount of steam going into the turbine needs to be regulated to ensure that the turbine doesn't start spinning too fast and burn out the pump. The valve regulating the steam requires a small amount of electricity to monitor the turbine speed and adjust the valve position. Typically, when the nuclear plant loses outside power, the diesel generators kick in. If that doesn't happen, there are battery backups. If the situation goes longer than the batteries last, at least some plants have backup manual methods of keeping the turbine running at the right speed.

A high level discussion of reactor safety systems HPCI
A more biased link that explains further the capabilities of HPCI and RCIC (about halfway down the article). Emergency Core Coolant Systems

Did you ever get that tour, or at least conversation you were hoping to? I work for a research group that is studying the Fukushima disaster's technical issues.
Would love to discuss your question about what systems can (or can't) handle these major events at a boiling water reactor.
BTW, I used to live in Monticello.

Ha. Never got the tour. We tried but they don't do the tours any more for anyone. 9/11.