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something is leaking in europe
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Nusa:

--- Quote from: Buriedcode on June 30, 2020, 09:51:43 pm ---
--- Quote from: Nusa on June 30, 2020, 01:36:56 pm ---
--- Quote from: blueskull on June 30, 2020, 09:47:18 am ---Some news links?

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He's probably referring to this: https://en.wikipedia.org/wiki/1975_Banqiao_Dam_failure.

Many of the details were classified by China until 2005, but it's now clear it was a disaster arguably comparable to Chernobyl.

It's probably before your time, and the government has changed since then. But one can say the same thing about Chernobyl.

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Yeah the death toll on that link is "85,600 to 240,000".  Chernobyl was "projected" at 4000 (actual reported, 90).  Or are you comparing the two in terms of land area affected?

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Counting deaths depends on your criteria, never mind whether you can trust the official information sources that want to minimize the numbers. Do you only count those that died quickly, or do you count the ones that later died a result of the accident. People stranded without food or safe water in one case and radiation sicknesses in the other.

As for comparing by whatever criteria, that's been done by others, including TV documentaries.

My main point is that the governments have changed since then. China has changed a lot since the days of Chairman Mao. And Gorbachev's USSR isn't the same as Putin's Russa. Even if all the people from the old regimes haven't died off yet. And yes, I'm old enough to remember the previous administrations. I've no idea what's in the history books these days.
jmelson:

--- Quote from: jogri on June 30, 2020, 08:16:20 am ---You still need two separate failures before isotopes from nuclear fission get released into the atmosphere:
-one of the fuel cells has to rupture/get a tear in order to get those isotopes into the cooling loop
-the containment of the cooling loop has to fail to get them into the atmosphere

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Nope, not even close, for a Boiling Water Reactor.  The fuel elements are clad with Zirconium, chosen for its VERY low neutron capture cross section.  BUT, unfortunately, it is a HORRIBLE metal, expecially in contact with water at 300+ C.  The fuel elements leak all the gaseous radionuclides like sieves.  So, Xenon, Krypton, Iodine, etc. all just pass right through the thin Beryllium sheath.  If they didn't, the cladding would swell up and burst.  So, the gaseous fission products get into the water quite easily.  Then, they pass out of the reactor pressure vessel in the steam, and go to the turbine.  Note, the main steam line coming off the top of a BWR's steam dryer is the most heavily shielded part of the entire plant!  Why?  Because lots of these nuclides settle on the pipe and are not submerged under feet of water for shielding.  So, they have a massive concrete shield tunnel for the pipe to pass through.  Then, due to having to pump leaked air out of the condensers as explaind in my previous message, the radioactive gases just go up the vent stacks.  This is a continuous process at BWRs.  The steam turbines are NOT in the containment building, they are in the turbine hall.

--- Quote ---Yeah, could be that one of the RBMKs in Leningrad has had a failure (this somehow sounds familiar…). If i remember correctly those designs didn't employ a second containment around the core, so they could have had a ruptured fuel cell, had to remove it from the core and it vented some gas when it was out of the reactor->not everything went through the filters. Makes you wonder how on earth they planned to safely remove broken fuel rods from this reactor design...

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The RBMK1000 is a Plutonium production breeder reactor where they also use the heat produced for electricity and city heating.
A horrible design, with weak containment, some flaky power controls and the horrible feature of positive void coefficient.
A ghastly combination of potential trouble.

--- Quote ---(Edit: that still wouldn't explain the clearly airborne caesium: Those reactors use light water as a coolant, the caesium would have reacted with it to form highly soluble caesium hydroxide->perfectly bound in the water of the cooling loop. So we can conclude that the source of this radiation spike was probably NOT sitting inside a water pool (water would have also captured dust too).)

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Well, not in a pool of COLD water, anyway.  But, reactor loop water is not usually cold, and a major steam leak definitely can release the cesium and other low-volatility nuclides.

Jon
jmelson:

--- Quote from: jogri on June 29, 2020, 07:29:21 pm ---If you want to detect such events you need something that can discriminate between ions with different energies: That's a scintillator counter, and it is effing expensive (basically a orange sized monocrystal mounted on top of a photomultiplier).

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There's a guy selling slabs of Bismuth germanate (BGO) on eBay for $20.  That's a chunk 25 x 25 x 10 mm, big enough to make a decent scintillation detector.  We had some bits and pieces at work related to Silicon Photomultipliers, so I built up a small detector.  It has a bias supply for the SiPM bias voltage, amplifier and discriminator, and a piezoelectric beeper.  It works quite well, getting a fewe hundred clicks a second from the Cs-137 check source in my Geiger counter.  The only tricky part to get is the Silicon Photomultiplier, they are kind of a new part.

Jon
helius:

--- Quote from: jmelson on July 01, 2020, 02:53:42 am ---The only tricky part to get is the Silicon Photomultiplier, they are kind of a new part.
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Would a mercury-cadmium-telluride detector not work here?
jogri:

--- Quote from: jmelson on July 01, 2020, 02:44:02 am ---Nope, not even close, for a Boiling Water Reactor.  The fuel elements are clad with Beryllium, chosen for its VERY low neutron capture cross section.  BUT, unfortunately, it is a HORRIBLE metal, expecially in contact with water at 300+ C.

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No, they use a zirconium alloy, beryllium is used in moderator rods. It would be an absolutely horrific choice for a pressure vessel as it is extremely brittle, reacts with oxygen (you have a lot of dissolved oxygen in your water, especially in open spent fuel pools) and it absorbs alpha radiation-> gets converted to carbon, you really don't want that.

Btw, those rods are quite sturdy, and because they always have an extremely high outside pressure due to the superheated water and quite a bit of expansion room for gases (they have springs to push the pellets together->also a good way of dealing with the gases) they are probably rather good at containing gases, especially really fat ones like Xe, Kr and I.


--- Quote ---Well, not in a pool of COLD water, anyway.  But, reactor loop water is not usually cold, and a major steam leak definitely can release the cesium and other low-volatility nuclides.

--- End quote ---

Well, if there really was a steam leak like you described why didn't we register a spike for iodine and the noble gases? They are a notorious PITA to filter out, so we would have seen a lot of them and not so much stuff that can be filtered quite easily.
And i heavily doubt that you would get a lot of caesium leakage from a steam leak as the hydroxide that forms when it comes into contact with water is one of the most soluble hydroxides out there (3kg per litre of water @20°C, let that sink in), you would get a few grams of CsOH in hundreds of tons of water->i doubt that the release of a few kg of water in the form of steam would lead to a spike like that.

Let's consider where the Ruthenium and Caesium might have come from:
-could they be the decay products of some gaseous fission products that escaped? Well, Caesium can't come from that: Cs can be created via a beta minus decay of Xenon, but neither Cs-134 nor 137 form. What about Ruthenium? It sits between a lot of metals, so no.
-could they come directly from U-235 fission? Probably, the products of a fission reaction are roughly the same weight, and since both Cs and Ru are roughly half as heavy as uranium they might have formed in two different fission reactions.
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