Feeds

Fukushima is a triumph for nuke power: Build more reactors now!

Quake + tsunami = 1 minor radiation dose so far

5 things you didn’t know about cloud backup

Letting off some steam

What the Japanese powerplant chiefs decided to do at this point is vent off some of the steam from the containment vessels in order to cool the interiors down. At this point the steam is not contaminated with any long-lived nasties, but it has been well soaked in neutrons and thus it contains quite a lot of very short-lived (half-life measured in seconds) radioactive materials such as Nitrogen-16. Within a minute of being released, such steam is just steam again, but it is radioactive when it comes out.

This is obviously emotive stuff – radioactive gas leaks – even if it is harmless to anyone beyond the plant fence (the workers inside are in protected control rooms or wearing protective gear).

So the situation is being managed and the cores are being kept cool by venting off steam. Power is restored by mobile generators to most of the reactors and soon their cooling systems are running again for a smooth shutdown.

But in two cases the normal cooling systems couldn't be made to run again even once mobile power arrived on scene. The normal systems use very pure de-mineralised water, and the plant operators couldn't get a supply of this running again at these reactors. Water adulterated with other things – such as sea salt – is less desirable, as its use means that other radionuclides are generated in small quantities: also it will cause a lot of expensive equipment corrosion and so forth.

But after some time, water levels inside the three cores sank low enough from the venting that hot bits of core started to stick up out of the liquid. These parts were then being kept cool much less effectively, and trace amounts of the caesium and iodine isotopes powering the residual heat reaction were detected in the air outside the plants. This first happened on Saturday.

The plant operators thus bit the bullet and fell back on yet another backup system: they injected seawater mixed with boric acid (liquid control-rod material) into the cores. This meant a fair bit of expensive damage to the two reactors, and also that the steam emitted when venting would be slightly more radioactive due to the salt and other trace chemicals in the sea water.

This is why the Japanese operators have chosen purposely to release the steam from these reactors, not into the atmosphere, but into the interiors of their reactor buildings. These too can be made gas-tight in order to contain leaks from the containment vessel, though they aren't terrifically strong and able to hold massive pressures.

The idea was to hold the steam in the buildings for the necessary short periods until it was no longer radioactive at all before letting it out of the building – and then venting off some more steam into the building, so cooling the cores. Holding the steam in the buildings wasn't really necessary – more of a gesture than anything else – but it was done nonetheless.

Unfortunately this decision has proved to be a PR blunder rather than a bonus. Steam which has been superheated as in a reactor core can break up into hydrogen and oxygen, which is naturally an explosive mixture. At Chernobyl, this actually happened inside the containment vessel and the resulting explosion ruptured the vessel, leading to a serious release of core radioactives – though this has had basically zero effect on the world in general nor even much impact on the area around Chernobyl.

Build a business case: developing custom apps

Next page: Under control

More from The Register

next story
Vulture 2 takes a battering in 100km/h test run
Still in one piece, but we're going to need MORE POWER
Boffins ID freakish spine-smothered prehistoric critter: The CLAW gave it away
Bizarre-looking creature actually related to velvet worms
TRIANGULAR orbits will help Rosetta to get up close with Comet 67P
Probe will be just 10km from Space Duck in October
ANU boffins demo 'tractor beam' in water
The current state of the art, apparently
China to test recoverable moon orbiter
I'll have some rocks and a moon cheese pizza please, home delivery
What does a flashmob of 1,024 robots look like? Just like this
Sorry, Harvard, did you say kilobots or KILLER BOTS?
NASA's rock'n'roll shock: ROLLING STONE FOUND ON MARS
No sign of Ziggy Stardust and his band
Why your mum was WRONG about whiffy tattooed people
They're a future source of RENEWABLE ENERGY
Vulture 2 spaceplane autopilot brain surgery a total success
LOHAN slips into some sexy bespoke mission parameters
prev story

Whitepapers

Endpoint data privacy in the cloud is easier than you think
Innovations in encryption and storage resolve issues of data privacy and key requirements for companies to look for in a solution.
Implementing global e-invoicing with guaranteed legal certainty
Explaining the role local tax compliance plays in successful supply chain management and e-business and how leading global brands are addressing this.
Top 8 considerations to enable and simplify mobility
In this whitepaper learn how to successfully add mobile capabilities simply and cost effectively.
Solving today's distributed Big Data backup challenges
Enable IT efficiency and allow a firm to access and reuse corporate information for competitive advantage, ultimately changing business outcomes.
Reg Reader Research: SaaS based Email and Office Productivity Tools
Read this Reg reader report which provides advice and guidance for SMBs towards the use of SaaS based email and Office productivity tools.