Welcome to Nuclear Power 101

So last night I made a post showing Nuclear fuel rods glowing, people commenting wanted more so here we are.

This post will cover the basics of the life cycle of Uranium- most Power plants utilize Uranium-235. Are there other types- yes... but U-235 is by far the heavyweight.

So this is uranium. A block of stone- literally. Uranium is found all over the globe- it is found in small amounts in most rock.

This is a breakdown of the uranium deposits in the US. You will notice this is almost an overlay of the granite deposits. That's right- if your house has granite- you own some uranium already!

Yellow cake Uranium. Movies have made this form of Uranium well known. This is simply Uranium in powdered form. Pure in the sense that it is only Uranium. However, Uranium comes in several isotopes. U-235, U-236, U-238. U-235 is the one that is used to maintain a chain reaction in power plants.

These are centrifuges and Iranian scientists. These pictures became famous after the US destroyed their centrifuges via a cyber attack.

Centrifuges work by spinning the yellowcake and causing on a molecular level the isotopes of Uranium to stratify. Allowing U-235 to be isolated and collected in higher quantities, also known as enrichment.

So- most US plants utilize around 4% enriched Uranium- meaning 4% U-235. With that enrichment, the fuel can be used for approximately 6 years before being completely depleted.

While I have a soap box- this is the reason from a technical perspective why the Iranian deal was so poor. We limit them to 30% enrichment and their claim is "it's only for peaceful means". There is ZERO reason to need anything near that high... unless you want to make bombs!

But I digress...

Once fuel has reached the proper enrichment it is formed into fuel pellets.

The fuel pellets are then stacked inside a fuel pin, usually made of zirconium alloys. The pins are housed into a bundle- pictures on the right.

Once in the core, rods are aligned into assemblies. The red center X is a control rod- this can be removed and inserted as needed to control reactivity, which in turn can control reactor power.

Are there more things that are involved with controlling reactor power... yes... am I getting into them right now... no.

This is a fuel rod (already activated, not new) being moved into the fuel pool during refueling. As I said fuel lasts 6 years, refueling occurs every 2 (at my plant- cycles can vary). Fuel that is not totally spent gets repositioned in the core almost every outage.

This is a flooded reactor core. The "cattle shoot" is used to move fuel from the core to the fuel pool while keeping it under water- radiation purposes.

Fuel being put back into the core. The blue glow is called the Cherenkov effect. Note it is not green as shown in many movies.

Once the fuel is spent- it will stay in the fuel pool for several years until its radioactivity lowers a few half lives.

Then the dry fuel cask shown above is lowered into the fuel pool and filled with fuel bundles. It is then lifted out, drained and sealed.

Many sites have utilized a horizontal storage system to store full casks. They are designed to be air cooled and safe... forever.

So what is the long term storage plan. Well here in the USA we had one. We spent Billions to complete it. It is called Yucca Mountain- fully ready to store spent fuel under a mountain for the next 10,000 years. Designed with warnings in the top 10 most spoken languages of earth engraved everywhere.

Why aren't we using it you ask. Simple answer is political reasons. Unfortunately Nuclear power is not and has never been a bi-partisan issue. Dems don't like it, Republicans do. And when Obama was first starting to make his political debut, Harry Reid said he would back him (one of the first to do so) it he vowed to never let Yucca Mountain be used if he made it to office. The rest is history.

So about me- I am a mechanical engineer. I worked for the US navy right out of school and was qualified (via a multi-year training program) to operate the nuclear reactors of aircraft carriers (I was a civilian). After I left I took a job as a system engineer at a nuclear power plant. Then a few years later switched back to operations where I have a SRO license.

I am willing to post about anything people ask about- just need a high enough response- to gauge interest.

**edit: link to Nuclear power 102 - http://imgur.com/a/yaMw0
it answers the #1 comment from this post.

**edit: link to Nuclear Power 103 - Fun facts http://imgur.com/a/TOuHz

**edit: link to Nuclear Power 201 - PWR vs BWR http://imgur.com/a/mjIHJ

**edit: link to Nuclear power 202- chernobyl http://imgur.com/a/lGVxj