# Category: English

A surprisingly good outreach platform has turned out to be Quora.com, a Q&A site where people ask questions and let anyone answer. So I will be replicating some of my answers from there to here. Enjoy…

## Nature showed us how to do it, and it works great!

This is a nuclear waste repository, that held waste for 2 billion years.

Yes, you read that right: 2,000,000,000 years. That is 20,000 times more than what we consider to be adequate for a repository. And the only reason it is not longer than that is because…

a. that is how much time has passed since the waste was created

b. the waste has now decayed, completely. [1]

In the 1970’s, the Uranium ore find at Oklo, Gabon, Africa, gathered attention, because there was something “wrong” with the ore. It was as if the Uranium had already been used in a reactor.

As it turned out, it had indeed been in a reactor, a natural reactor. Billions of years back the isotope mix of Uranium was more like that we use in artificial reactors today. So all it needed was a bit of water to moderate the neutrons and — voilà! — nuclear fission, just like we do it today.

Nuclear fission means nuclear waste. These natural reactors also made waste. That meant a golden opportunity for us to examine what happened to the waste. The conclusion was astounding:

The waste stayed in place and moved less than 10 feet / 3 meters

This is despite the fact that the waste…

• was not packaged in fuel bundles
• was not encapsulated
• was subjected to violent temperature swings (these reactors worked in cycles of a few hours)
• was washed through by water for hundreds of thousands of years

The chief finding was that long-lived waste — the Transuraniums like Plutonium and Americium and other such Actinides — binds chemically to rock in a reducing environment and remains entirely immobile.

This is the key to why geological repositories work. Nature told us so. And that is why we are building repositories that way.

The Swedish KBS-3 method builds on the findings of Oklo and further research since the 1970’s. KBS-3 is already approved in Finland, and is in the process of being approved in Sweden.

KBS-3 — besides using the reducing environment of the bedrock — also adds the following barriers.

• The fuel remains in the fuel rods, i.e. clad in Zirconium alloy. They are then placed in…
• Cast iron holders. The cast iron ensures rigidity, toughness, and that the environment will remain reducing even if water enters the…
• 2 inch / 50 mm thick corrosion resistant copper capsule that encapsulates the fuel bundles and their holder. That capsule is then surrounded by…
• A layer of water absorbent Bentonite clay. The clay acts as soft padding to keep the capsule from being subjected to movements of the bedrock. It is also meant to be wet, because when it wets it swells to a pressure of 50 atmospheres, and is pressed into all the cracks and fissures around…
• The bore hole, made 500 meters down into geologically stable bedrock, with a reducing environment and only small water movement.

The only thing that the Oklo reactors had was the reducing environment, and that alone held the waste in place for 2 billion years. KBS-3 will do the job.

So anyone that says there is no plan or no method or no site to deal with nuclear waste, is speaking — put in the plainest of the Queen’s English — complete and utter bollocks.

## Footnotes

[1] The half-life of Plutonium-239 is: $\lambda = 24,100 y$

So the tenth-life of Pu-239 is: $t_{1/10} = \lambda \left(\frac{ln(10)}{ln(2)}\right) \Rightarrow$

$t_{1/10} = 24,100 \cdot 3.32 \approx 80,000 y$

So 2 billion years makes for…

$2,000,000,000 / 80,000 = 25,000$

…25,000 tenth-lives.

After about 110 or so tenth-lives, the original amount would have had to fill out the entirety of the known observable universe in order to have one atom left.

It is now possible to watch the complete Pandoras Promise documentary on Youtube. It is a very important movie and the further it reaches the better!

a

Professor Janne Wallenius of the Reactor Physics division at The Royal Institute of Technology has started a kickstarter for funding a demonstration of a new material they have developed. The main issue with lead cooled reactors is corrosion of steel structures and erosion of moving parts (like pump impellers) and Wallenius team has developed a new kind of steel that might solve those issues.  What is needed is a larger demonstration of the materials properties and that is what the kickstarter is about.

It is an interesting way to fund research and well worth spreading the word about, so check it out!

What is this, the fancy clothes brand from the famous tennis player decides to make a statement in the debate about nuclear power? A closer scrutiny reveals that it says “nudeclear”, not “nuclear”. The press release is anyhow a mind game that may provoke some people:

If Björn Borg could decide, the whole world would overflow with nudeclear power; a world where we all live in a sensual high radiation zone

So what to make of it, has the PR people of Björn Borg gone completely insane, or is it just business as usual? Apparently it seems to be the latter. Half a year ago they had a campaign called Weapons of Mass Seduction where somebody had the task to drop 450 pairs of underwear over the North Korean capital Pyongyang. And it was accomplished.

From NPYP we find the ripoff of the name to be amusing and would like to get hold of some of the “Nudeclear waste” stickers seen on the barrels in the picture above. Besides that we do not think it will affect the nuclear debate in any way, but it is promising that a company dares to play this kind of game, maybe the issue of nuclear power isn’t that controversial after all.

Are you provoked? Here is our recommendation:
* If you are anti nuclear: Relax, it’s just underwear!
* If you are pro nuclear: Have a good laugther!

Public opinion in most countries seem to favor renewables as the future source of carbon-free power. Nuclear power is often regarded as a thing of the past, and an option that is “too expensive” or “too risky” to replace coal. In reality, when we put our money into renewables, we snatch defeat from the jaws of victory.

### Renewables don’t get us far enough

These perceptions is one of the main reasons that the EIA International Energy Outlook 2013 has global electricity production doubled in the year 2014, with relations between power sources virtually unchanged. I.e. everything doubles, including coal/gas:

This prognosis puts the hopes of the renewables’ crowd to shame. Nuclear power remains the only proven option to combat fossil generation, but its growth is severely hampered by the ever-increasing and largely unnecessary regulatory burdens.

In the graph below, with data mostly from the BP Statistical Review of World Energy 2013, the rapid pace of nuclear penetration in pioneer countries is obvious. When you get off the starting blocks with nuclear, 50% or more can be reached in a mere decade. Just as obvious is the comparatively slow pace of wind and photovoltaic adoption.

Denmark does have a fairly steep wind curve recently, but we should remember that Denmark is a very small country that relies heavily on its neighbors’ power grids for balance. Larger countries and areas such as Germany doesn’t have larger neighbors, and cannot easily integrate that much wind power.

### Germany: The Black Sheep of Europe

Germany, the major industrial power of Europe, is the prime example of energy policy gone totally wrong. Last year, it actually increased its coal generation by 3.9%, from 76.0 million tonnes of oil equivalent (MTOE) to 79.2 MTOE. Half of the electricity of Germany is from coal, but it could have been rid of all of it already, had it pursued nuclear power instead of wind and solar. Here’s a table of German investment costs:

As can be seen, electricity investments in renewables amounted to a whopping 60 billion euros from 2000 until 2008. That money could have built them 15 nuclear reactors with an output of some 140 TWh/year already completed today. The investments from 2009-2012, ie 76 billion euros, would suffice for an additional 19 reactors with an output of some 180 TWh to be completed in the coming few years. Instead of these 140+180 = 320 TWh/year of electricity for 60 years of lifetime, Germany now has 60 TWh/year of wind and photovoltaics with 20 years of life. Germany’s coal generation is some 280 TWh/year, so had the money been put into nuclear, the coal would soon be history.

### Consequences of failed policy

What’s more, had Germany pursued the nuclear path, they wouldn’t have locked in a FiT surcharge of 5 euro cents or more per kWh for many years to come, and unneccessary cancer deaths would be down by thousands each year! Note: This does not include costs that are external to intermittent power sources, for strengthened grids and for industries to create power backup solutions to handle frequency fluctuations. And, of course, hundreds of million tonnes of CO2 wouldn’t have been released into the atmosphere.

### The Future

Renewables investment in Germany, for electricity only, from 2010-2050 in the table above is put at a staggering 149+407=556 billion euros (there are higher estimates up to a trillion euro). This excludes transmission upgrades, backup power plants, demand side managements costs, industry consequences and more, yet it would suffice to build some 140 nuclear reactors that would produce 1300 TWh/year – probably more considering economies of scale. Germany today consumes 600 TWh/year and wants to cut that with 25% in order to reach its goals.

While there are signs that Germany’s consumers, voters and politicians doesn’t have the stamina to continue on this painful and polluting path for long, some of it, as EIAs projection shows, will be replicated in the rest of the world. The world could get rid of coal in short order, if it puts its money on the right horse. Will public opinion and regulatory regimes allow that? You decide!

Just a short blog post during a quiet period that has unfortunately reigned on this blog for a while. Recently during the voting for the German greentech awards something tremendously embarrassing happened! A nuclear reactor of all things had the audacity to win the voting. That led to a dilemma of course because nuclear anything can’t be allowed to win anything in Germany, especially not when the environment secretary himself is the patron of the award.

So what did they do, they changed the rules of course to ensure that the voting has no meaning (““selection of nominees and winners will ultimately be done independently by the Jury of Awards GreenTec. Legal action is excluded.”) and that nuclear will never be allowed to win (“and our jury reject nuclear energy in any form categorically!”). I wonder how they would treat geothermal energy (radioactive decay anyone?!?)…

The story is told much better over at the Rainer Klute’s blog, “How to stash a nuclear reactor away”, I suggest everyone read Rainers post and support his petition!

Now its time to return to the wonderful Swedish midsummer festivities exquisitely summarized in this IKEA commercial.

We have discussed the time behavior of the neutron flux and reactivity feedbacks. Now it is time for the the thermal side of things. The point kinetics model describes how much energy is produced in the fuel, but we also need a model for how the energy is transported within the fuel, through the fuel cladding and into the coolant. To figure it out we need models for heat conduction through the fuel and cladding, heat transfer to the fluid through convection, properties of the fluid at different temperatures and pressures and so on. This blog post will deal with the heat conduction in the pellet and through the cladding.

## Continue readingWhy don’t nuclear reactors go kaboom? A reactor kinetics primer part – 3

##### Advanced test reactor Foto: Matt Howard, Source: Wikimedia Licens: Creative Commons Attribution-Share Alike 2.0 generic

Its time for some more fun with reactor kinetics, in the last post we ended by looking at the point kinetics equation with one group of delayed neutrons. In this post as I promised we will talk about reactivity feedbacks. To brush up your memory, reactivity is defined as:

Nuclear reactors contain tons of fissile material and nuclear bombs contain only kilograms of fissile materials, so why does one of them explode with enough force to flatten a city but the other doesn’t? I will pull out some latex skillz and geek it out with equations to describe the physics behind whats in nuclear engineering is called reactivity excursions or RIA (Reactivity Insertion Accident). The level of these blog posts will be such that an interested and fairly math savy person can understand and calculate these kind of things on their own.