Note: My aim here was not to accurately describe nuclear power or detail the complex events that occurred at multiple reactors over two weeks – more to give a simplified overview of how the plant works and the kind of challenges the engineers faced.

Two weeks ago we were perturbed to hear of the terrible earthquake and tsunami which devastated Japan. In the aftermath, one of the main problems was the breakdown of cooling systems at the Fukushima Dai-ichi Nuclear Power Plant, which threatened to release radioactive material, making the disaster even worse.

What happened at Fukushima?

To explain this question we first need to understand how a nuclear power plant works. Then we will look at what happened during the earthquake, and why the problems at the plant occurred.

Fukushima Dai-Ichi, which means Fukushima Number One, is one of the biggest nuclear power plants in the world with 6 reactors producing 4.7 GW of electricity.  It was built in the early 1970s using a design called the Boiling Water Reactor.

How does the power plant work?

Basically, Fukushima is pretty similar to other kinds of power plants, like our Huntly coal power station. There is a heat source which is used to boil water into steam. The expansion of the steam powers turbines to produce the electricity.

After the turbine, you’ve got all this steam which needs to be turned back into water. This happens in the condenser, which is basically like a giant radiator. It is usually cooled by another water source; at the Fukushima power plant, it was cooled by seawater.

After being cooled by the condenser, the water can be run through the boiler again. You can see that this is a closed loop, so it doesn’t waste huge quantities of water.

The main difference between the Huntly coal power station and a nuclear power plant is that instead of coal, the nuclear power plant uses nuclear fission as the heat source. Each of the six reactors contains around 50 tons of enriched uranium.

Uranium nuclear fission starts with a stray neutron, which is a tiny particle. If the neutron gets absorbed by a uranium atom, that atom becomes unstable and splits to produce two smaller atoms. This splitting releases a lot of energy. It also releases more neutrons, which can cause the same thing to happen to neighbouring uranium atoms.

In a nuclear explosion, there is a cascading chain reaction which splits all of the atoms in a few milliseconds, causing a nuclear explosion.

In a nuclear reactor you want these reactions to occur at a steady rate, producing an even amount of heat over time. The way you do this is by having the uranium spread out inside the reactor, and by controlling the neutrons.

So you can see this is the inside of the nuclear reactor. The uranium is in fuel rods, which are several metres long. They are separated into a grid, and between the fuel rods there are control rods, made of graphite, which absorbs neutrons. You can slide the control rods in or out of the reactor to control the fission of the U-235.

If you want to shut it down, you slide in the control rods, the neutrons will be absorbed, and the fission will slow down, and ultimately come to a halt.

So that’s an overview of how a nuclear reactor works.  But what happens when disaster strikes?

Japan, like New Zealand, is a geologically active country, and the plant was designed to resist both earthquakes and tsunamis.

Unfortunately, the 9.0 earthquake which occurred on March 11 was an extremely powerful event. It exceeded the earthquake design strength by 100%. Despite this, the plant wasn’t particularly damaged by the earthquake itself.

Within minutes, the reactors were shut down, with the control rods being fully inserted.

About ten minutes after the earthquake a 12 metre tsunami struck the plant. The plant is surrounded by sea walls designed to resist a tsunami – but the walls were designed with a 6 metre tsunami in mind.

When the tsunami struck, it did not damage the reactor buildings directly.

What it did damage was almost all of the associated infrastructure surrounding the reactor building.

Whole buildings were washed away or inundated with saltwater and debris. The electricity lines which bring power to the plant from outside were destroyed. The diesel generators which operate the pumps were washed away. And the pumps themselves were affected too.

As I said, the reactor cores have been shut down.  Unfortunately, shutting down a nuclear reactor isn’t like turning off a light switch. The reactor still produces around 6% of peak heat. This called decay heat and it will gradually stop over time.

Now 6% doesn’t sound like much. But these are massive, industrial power plants. The decay heat was 140 MW, and it takes a lot of cooling water to remove this heat from the reactor.  The reactor is designed to operate with water running through it all the time, taking away the heat.  Usually, pumps take care of this with no problem, even in an emergency when plant power is lost.

Without any water running through it, this heat is going to build up inside the reactor.

The engineers at the plant were able to get some pumps running to push water through the reactor, but that water wasn’t being cooled by the ocean water.  So the water in the primary loop became very hot, 100 degrees. At that point, its not doing actually any useful cooling. So the reactor core continues to build up heat.

Like anything else, the fuel rods have a melting point. The reactor got so hot that the fuel rods started to melt. This can change the distribution of the uranium within the reactor, making the situation worse.

As the heat continued to rise, the pressure inside the reactor was increasing. The reactor normally operates like a pressure cooker, at about 75 times normal atmospheric pressure. Its built pretty strong to contain that pressure, but at some point it can’t take any more. To avoid a blowout which would damage the reactor vessel, the workers started to vent the steam, to relieve the pressure. Along with the steam and some mildly radioactive material, hydrogen was released – one of the byproducts of fission. Hydrogen gas is explosive, and at some point the hydrogen gas ignited and blew the roof off the reactor building. The reactor itself wasn’t damaged, but the loss of the roof means that the vented steam was carrying the radioactive material directly into the atmosphere.

Meanwhile, the engineers were working to restore a power connection to the plant and get more water flowing through the reactor. They were eventually able to get power connected to the plant by rebuilding 1 km of power lines. They then started pumping seawater directly through the reactor to cool it down.

They were able to prevent a meltdown, which would cause damage to the reactor and possibly release a greater amount of radioactive material into the atmosphere.

Now keep in mind that these reactors were built in the 1970s, before modern computers. Compared to modern reactor designs, the reactors are ancient, creaking hulks.

With almost all of their cooling infrastructure destroyed, plant workers were able to ensure that the reactors did not melt down and prevented a major radioactive disaster.  In the face of this remarkably powerful and destructive event, they did a remarkable job.

Thank you.

I’ve made a simple webpage which uses the data in that list to build a map of the earthquake-prone buildings in Wellington.

Check it out at quake.howison.co.nz

I took a few panoramas.  What can I say, it’s just kind of my thing I guess!  :-)

View over Wellington overlooking the lighthouse

View of Petone from the WWII anti-aircraft emplacements

View of the various buildings in the middle of the island

I’ve been geeking it up tonight installing Chromium OS on my netbook, and decided a head-to-head boot-up speed test was in order.

I measured how long it took for each OS from pressing the ‘on’ button to when the browser screen rendered.

• Chromium OS: 27 seconds
• Ubuntu: 89 seconds
• Windows XP: 97 seconds

So Chromium OS is a pretty damn fast way to bring up a browser!

Extended speed test results on my EEE1000:

• Power button -> load BIOS -> load GRUB takes 12 seconds
• After GRUB, Chromium login pops up in 11.5 seconds
  • Chrome browser is available 3.5 seconds after that
• After GRUB, Ubuntu 10.10 login pops up in 32 seconds
  • After login, Chrome browser is available in approx. 45 seconds
• After GRUB, Windows XP login pops up in 33 seconds
  • After login, Chrome browser is available in approx. 52 seconds

Chromium Notes

My impression of Chromium is that it is pretty good at what it is meant to be: a simple, efficient net appliance.

Chromium is only experimental right now, but it is very usable.

Devices

Wireless and ethernet worked perfectly straight away, but my Vodem (a Huawei K3565-Z) wasn’t recognised.  The OS didn’t seem to like turning the wireless device on and off.

A wired mouse worked immediately.  The battery indicator works perfectly and looks good sitting beside the icon for internet connectivity. Sound worked out of the box too, including my netbook’s mute, volume-up and volume-down function keys.  There is no on-screen mute/volume graphic though.

Browser

It is quite amazing how much screen real estate Chromium leaves open for the browser, especially in the super-efficient Compact Nav Bar mode.

Youtube works out of the box, as do Flash games like Robot Unicorn. Flash does struggle a bit however.  This is possibly a hardware support issue.

I found a persistent SSL error on pageload in HTTPS websites, which include Gmail and Google Analytics.

Files

You can save files to, well, somewhere on the hard drive, but you can’t re-upload them from wherever they are.  You can also save files to inserted media (USB sticks and SD cards), but again,  you can’t upload files from these media.  The file-browse window just comes up blank.

A bit of Googling turned up a way to look at files that works (use the file:// protocol in the address bar) but it still isn’t clear how to upload files, eg, to Gmail, and there appears to be no way to delete files.

Keyboard Shortcuts

There is a really nice feature where you can press F8 to show all the available keyboard shortcuts – mostly just the standard Chrome shortcuts -but also a memory manager and the Chrome task manager where you can kill misbehaving tabs.  I promptly decided this keyboard map should be standard in every application and OS.  :-)

I noticed that for some actions, using keyboard shortcuts resulted in a fast result (eg opening a new tab) whereas using the mouse to perform the same action seemed sluggish.  For other actions, the reverse seemed to be true.  This seemed to be true overall, some actions were quick, others slow. Kind of an uneven user experience.

Overall Impression

It is reasonably obvious that Chromium is still experimental – installing it is not for faint of heart (although trying it on a USB stick is easy).

Overall, the browser feels reasonably fast, but the menus, connection options, etc, feel quite slow and a few times they stopped responding at all.

The net-based OS is definitely quite a different concept – installing a new OS usually involves some personalisation like setting your favourite desktop wallpaper and copying over your own music to listen to.  Because you don’t do these things, Chromium feels a bit anonymous, it doesn’t quite feel like home.  On the other hand, you might have a custom image on your Google homepage, and you could listen to your saved Grooveshark playlist – and of course,  thats exactly what Google has in mind.

It strikes to me that the quick start-up time bridges the gap between surfing on the iPhone – instant-on, but a teeny screen – and on a netbook – slower to turn on, but a much larger screen and nicer keyboard input.

I can also see some interesting possibilities like an in-browser app to play music from local network shares, but that does seem like a slippery slope towards reinventing the whole OS wheel inside the browser.

Conclusion

With a bit more development, a UI speed-up, vodem support and of course getting the file-handling bugs out of the way, I can definitely see myself using Chromium a lot, eg when I want to:

• send an email in Gmail
• check the weather forecast
• look something up quickly on Wikipedia
• mindlessly browse Reddit for 20 minutes

… I would select Chromium simply for its incredible start-up speed.

Congratulations!

It was a beautiful ceremony in the Wellington Botanic Gardens, officiated by Father Kevin. You can see me on the right as best man, and Chelsea on the left as matron of honour.

There was a yacht race going on in the bay.

We’ve had beautiful weather for several days in a row … it’s getting dangerously hot and sunny, time to start wearing sunscreen and silly hats I think.

This is for Speech 6: Vocal Variety.  In retrospect the topic didn’t really suit the vocal variety goals I was meant to aim for, but I think I did succeed in slowing down, speaking louder, two things I have been trying to improve on.

Chair, fellow Toastmasters, guests – have you ever gone looking for the spare batteries in a drawer somewhere and found that it was crammed full of junk?  Stuff that you sort of, kind of want to have around, but you haven’t actually used in the last ten years?

I have.  Now I don’t consider myself a packrat, but up until a few weeks ago, you could open a drawer or a cupboard in any part of my house and find a surprisingly large quantity of … stuff.

Stuff like old torches that don’t go.  The pizza cutter that you’ve never used.  A broken fridge magnet that you keep meaning to glue back together.  Books that you don’t really plan to read.

And I eventually realised that it was weighing me down.  It takes up space.  When you move you have to pack it up and carry it.  It needs a place to go, like a drawer or a cupboard.  You need a bigger house to have everything in.

You know they say, “use it or lose it”.  If you don’t use something, it decays.  All this junk just sits there and it gets dusty or rusty or eaten by moths.

Someone once said that there should only be two kinds of thing in your house.  Useful things, that you use often, like your computer or your bath towel.  And beautiful things, like the paintings in your lounge or books by your favourite author.

Everything else should go.

I read that and I thought – Yeah.  Yeah.  So I decided to do it.  I was going to declutter.  One drawer and one shelf at a time, I sorted my Stuff into two piles:

• Keep
• Get rid of

It is surprisingly easy to get rid of things.  A whole bunch of stuff just went in the recycling bin.  A lot of stuff went in the rubbish, like the broken torch and the old packaging that I will never need again.

Another pile of stuff went to the Salvation Army store, old clothes, books that I’ve never read, old schoolbags.

And I even managed to make some money selling stuff on Trademe.  There was the spare iron.  Who needs a spare iron?  $16 plus postage.  The tiny sewing machine which was really cool but I never used.  Someone bought it for more than I paid for it!

I found that I had five whole boxes of old university notes and phone bills. I was able to get rid of almost all of it because I really don’t think I need my old exam notes about how the liver works or the power bill from 2002.

Actually – I’m not going to lie to you folks.  I got a bit emotional going through all that paperwork.  Some of it is little memories, good memories and bad.  And you know, the thing is with those bad memories – you can just throw that bit of paper away.  It felt great.

At the end of all the decluttering, I realised that there was some things in my house that don’t actually work very well.  For example, I realised that I was using a dining room chair as my bedside table, and a horrible old set of drawers that was half empty because the drawers didn’t slide in and out properly.

It was just ridiculous.  So I got a really good deal on matching bedside drawers on Trademe.  The dining chair went back where it belongs, and the old set of drawers can go to the Sallies.  Now that part of my house just works that much better.  Wonderful.

Overall, my house is tidier and less crowded.  If we have to move again, it will be that much easier.

And you know, I really enjoyed the process of getting rid of most of my junk.  There’s still more to get rid of it, but the thought of getting rid of stuff isn’t scary anymore.  When it comes to your possessions, I reckon less is more.

I highly recommend decluttering.  Its so easy.  You go through one shelf or drawer at a time, sorting stuff into two piles:  Keep and Get Rid Of.  You recycle or trash the real junk, donate the unwanted goods to the Sallies and sell anything worth money on Trademe.

And then, go ahead and change things that aren’t working.  Do you really need that wobbly coffee table?  Fix it, or get a better one.

Getting of your old junk leaves more room in your house and your life for the things you really want.  Go for it.