Fukushima: damage limitation | 319 comments (319 topical, editorial, 0 hidden)

Re: Fukushima: damage limitation (none / 0)

TEPCO to inject nitrogen into No. 1 reactor to prevent explosion | Kyodo News

Tokyo Electric Power Co. on Wednesday prepared to inject nitrogen into one of the reactors at the crippled Fukushima Daiichi nuclear power complex to reduce the potential risk of a hydrogen explosion, while it succeeded in stopping highly radioactive water leaking into the Pacific Ocean from the plant.
The nitrogen, an inert gas, is expected to be injected into the No. 1 reactor's containment vessel, a process that could take several days. Hidehiko Nishiyama, a spokesman for the government's nuclear agency, denied during a morning press conference that there is an ''immediate danger'' of explosion.
In addition to the task of maintaining the relative stability of all six reactors at the nuclear complex, the utility firm known as TEPCO has also been engaged in efforts to stop highly radioactive water from leaking into the sea and cleaning up contaminated water within the plant.

Any idiot can face a crisis - it's day to day living that wears you out.

by ceebs (ceebs (at) eurotrib (dot) com) on Wed Apr 6th, 2011 at 08:22:54 AM EST

Re: Fukushima: damage limitation (none / 0)

If they put nitrogen in, what do they do with the steam and other gases currently inside? Remember, this is the one reactor still under pressure.

_{*Lunatic*, n.

One whose delusions are out of fashion.}

by DoDo on Wed Apr 6th, 2011 at 09:22:49 AM EST
[ Parent ]

Re: Fukushima: damage limitation (none / 0)

To my way of thinking, if you add more gas, it's going to push the water down the reactor vessel, exposing more of the rods, unless there's some kink that higher pressure will force the steam in the cylinder back into liquid and somehow increases the depth of water offsetting that problem in a way that I dont understand.

Any idiot can face a crisis - it's day to day living that wears you out.

by ceebs (ceebs (at) eurotrib (dot) com) on Wed Apr 6th, 2011 at 10:10:40 AM EST
[ Parent ]

Re: Fukushima: damage limitation (none / 0)

Nuclear crisis (now fully accessible) | Kyodo News

NEWS ADVISORY: Nitrogen injection not to cause significant rise in radioactive leaks (22:55)

Any idiot can face a crisis - it's day to day living that wears you out.

by ceebs (ceebs (at) eurotrib (dot) com) on Wed Apr 6th, 2011 at 10:17:05 AM EST
[ Parent ]

Re: Fukushima: damage limitation (none / 1)

Water is effectively incompressible, isn't it?

Economics is politics by other means

by Carrie (migeru at eurotrib dot com) on Wed Apr 6th, 2011 at 10:22:19 AM EST
[ Parent ]

Re: Fukushima: damage limitation (none / 1)

Properties of water - Wikipedia, the free encyclopedia

The bulk modulus of water is 2.2 GPa.^[28] The low compressibility of non-gases, and of water in particular, leads to their often being assumed as incompressible. The low compressibility of water means that even in the deep oceans at 4 km depth, where pressures are 40 MPa, there is only a 1.8% decrease in volume.^[28]

Economics is politics by other means

by Carrie (migeru at eurotrib dot com) on Wed Apr 6th, 2011 at 10:23:34 AM EST
[ Parent ]

Re: Fukushima: damage limitation (none / 0)

erfectively, but the top layer of stem isn't is it?

Any idiot can face a crisis - it's day to day living that wears you out.

by ceebs (ceebs (at) eurotrib (dot) com) on Wed Apr 6th, 2011 at 10:33:58 AM EST
[ Parent ]

Re: Fukushima: damage limitation (none / 0)

No, but are the rods supposed to be cooled by water or steam?

Economics is politics by other means

by Carrie (migeru at eurotrib dot com) on Wed Apr 6th, 2011 at 10:36:03 AM EST
[ Parent ]

Re: Fukushima: damage limitation (none / 1)

heat transfer is meant to be much larger with water, but steam still has some levels of cooling effect apparently, according to one of the earlier discussions on the exposure of fuel rods

Any idiot can face a crisis - it's day to day living that wears you out.

by ceebs (ceebs (at) eurotrib (dot) com) on Wed Apr 6th, 2011 at 10:48:03 AM EST
[ Parent ]

Re: Fukushima: damage limitation (none / 0)

Boiling water reactor - Wikipedia, the free encyclopedia

Water exiting the fuel channels at the top guide is about 12 to 15% saturated steam (by mass), typical core flow may be 45,000,000 kg/h (100,000,000 lb/h) with 6,500,000 kg/h (14,500,000 lb/h) steam flow. However, core-average void fraction is a significantly higher fraction (~40%).

Economics is politics by other means

by Carrie (migeru at eurotrib dot com) on Wed Apr 6th, 2011 at 10:50:19 AM EST
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Re: Fukushima: damage limitation (none / 0)

Get out your old steam tables book... :-)

by asdf on Wed Apr 6th, 2011 at 05:23:09 PM EST
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But steam will cause what is left (none / 1)

of the zirconium to burn.

Not to be off topic, why aren't they feeding boron into the reactors? Except for one story about a request for boron from South Korea, I am not aware of a word about it since.

Given that we know for real that reactor no. 1 has gone critical several times since the accident (radioactive chlorine, the blue glow, heat spikes, and neutron episodes) they could actually be creating more heat than they are dissipating, as well as making the site more radioactive.

The Fates are kind.

by Gaianne on Wed Apr 6th, 2011 at 03:09:45 PM EST
[ Parent ]

Re: But steam will cause what is left (none / 0)

By the way, how did you end up looking into a hot fuel pool?

The last time I saw fuel rods
in a pool--which I admit was some years ago--the blue glow of Cherenkov radiation (that's the radiation due to beta particles traveling faster than the speed of light in water) extended out at least one half meter from the rods.
(It was very beautiful, by the way.)
The safe distance will obviously be very sensitive to your personal level of machismo.
It occurred to me later that standing near the edge of that pool was not the brightest thing I have ever done in my life.

Economics is politics by other means

by Carrie (migeru at eurotrib dot com) on Wed Apr 6th, 2011 at 03:28:05 PM EST
[ Parent ]

Heh. (4.00 / 3)

Had a friend in low-energy physics.

(Low-energy means nuclear.)

They had a research reactor for producing neutrons and such, studying energy levels in excited states in atomic nuclei, both stable and unstable.

If I understood correctly, this was background to test models targeted at the Island of Stability--heavier elements that might exist or that might be created, beyond the existing elements and beyond the gap of impossible elements.

They were pretty hands-on: Technicians ran the reactor, but they set up their own equipment (lead bricks, detectors, computer cables)--which meant they were in and out of the reactor building more or less daily.

The Fates are kind.

by Gaianne on Wed Apr 6th, 2011 at 08:58:18 PM EST
[ Parent ]

Boron (4.00 / 2)

NY Times: U.S. Sees Array of New Threats at Japan's Nuclear Plant (April 5, 2011)

The steps recommended by the nuclear commission include injecting nitrogen, an inert gas, into the containment structures in an attempt to purge them of hydrogen and oxygen, which could combine to produce explosions. On Wednesday, the Tokyo Electric Power Company, which owns the plant, said it was preparing to take such a step and to inject nitrogen into one of the reactor containment vessels.
The document also recommends that engineers continue adding boron to cooling water to help prevent the cores from restarting the nuclear reaction, a process known as criticality.
Even so, the engineers who prepared the document do not believe that a resumption of criticality is an immediate likelihood, Neil Wilmshurst, vice president of the nuclear sector at the Electric Power Research Institute, said when contacted about the document. "I have seen no data to suggest that there is criticality ongoing," said Mr. Wilmshurst, who was involved in the assessment.

It is implied that they're doing it already.

Economics is politics by other means

by Carrie (migeru at eurotrib dot com) on Wed Apr 6th, 2011 at 04:22:45 PM EST
[ Parent ]

Re: Boron (none / 0)

We saw that earlier. From the latest TEPCO status report:

TEPCO : Press Release | Plant Status of Fukushima Daiichi Nuclear Power Station (as of 8:00 pm, April 6)

-We have been injecting seawater into the reactor, but from 10:10 am on
March 26th, we started injecting freshwater (with boric acid).

This is for No. 2. The NISA status reports, however, for example the latest, mention "borated water" (sic!) for No. 1 (from 12 March) and No. 3 (from 13 March).

_{*Lunatic*, n.

One whose delusions are out of fashion.}

by DoDo on Wed Apr 6th, 2011 at 05:08:25 PM EST
[ Parent ]

Re: Fukushima: damage limitation (none / 0)

Increasing the pressure of steam will make some of it condense back to water.

Economics is politics by other means

by Carrie (migeru at eurotrib dot com) on Wed Apr 6th, 2011 at 10:49:24 AM EST
[ Parent ]

Re: Fukushima: damage limitation (none / 0)

Migeru dealt with volumetric change; I note that the hydrogen won't go away because some steam turns back to water, and pressure would increase anyway.

By the way, in one of the earliest threads, there was some link which described the injection of nitrogen to create an oxygen-depleted atmosphere as a standard (and automatic) anti-hydrogen-explosion measure during SCRAMs in some power plant types –maybe including the Fukushima type, I don't remember well.

_{*Lunatic*, n.

One whose delusions are out of fashion.}

by DoDo on Wed Apr 6th, 2011 at 11:59:48 AM EST
[ Parent ]

Re: Fukushima: damage limitation (none / 0)

TEPCO release on nitrogen injection, with two attachments. One is in English so bad I couldn't make much sense of it (more below). The other is a diagram, showing the route for nitrogen, and the blocked path for nitrogen injection by design (so they indeed did have had this).

One thing transpiring from the first attachment that they do fear a breach of the core, but from the outside (the meltdown would be from the inside), and that's how new hydrogen gas can get into the dry well. Another is that pressure is a problem in a different way: it drops due to the cooling of the reactor at the containment wall which also makes the steam condense.

_{*Lunatic*, n.

One whose delusions are out of fashion.}

by DoDo on Wed Apr 6th, 2011 at 05:00:02 PM EST
[ Parent ]

Re: Fukushima: damage limitation (none / 0)

NHK WORLD English

Tokyo Electric Power Company says the injection is aimed at preventing hydrogen from exploding inside the containment vessel at the No. 1 reactor.

The fuel rods remain nearly half exposed as the coolant water inside the reactor has not yet risen high enough.

Any idiot can face a crisis - it's day to day living that wears you out.

by ceebs (ceebs (at) eurotrib (dot) com) on Wed Apr 6th, 2011 at 05:36:43 PM EST
[ Parent ]

Re: Fukushima: damage limitation (none / 1)

NHK WORLD English