Thread by @gbrumfiel

Short 🧵: Data from the Chinese National Nuclear Safety Administration does seem to indicate a *slightly* elevated level of gamma radiation around the Taishan Nuclear Power Plant. These are the two monitoring stations closest (one on the left is at the plant).

The full list of monitoring at Chinese NPPs is here:
data.rmtc.org.cn:8080/gis/listtype1M…

As of yesterday, Taishan is at 153 nGy/h (153 nanograys per hour). That's above the level of other plants in the country.

The levels at both sites near Taishan NPP also seem to have been elevated since at least late May. This may be an indication that this has been going on for awhile, and is not an immediate emergency.

What's going on? According to this statement from @edfenergy, it seems like there is a build up of noble gases in the primary circuit. Noble gases are a bi-product of nuclear reactor operation, and also sometimes an indicator of a problem.

@edfenergy In particular, radioactive xenon (Xe-133) can be released from nuclear power plants during refueling or during accidents. Because Xe-133 is non-reactive, it can seep through pipes and buildings. If Xe-133 is building up in the reactor, it is very hard to contain.

But Xe-133 is not necessarily dangerous. It's non-reactive nature means that it isn't easily taken up by biological organisms. And it will disperse into the atmosphere.

The readings and statement show there's something going on. One poss is cracked or otherwise damaged fuel rods. That could lead to the excessive build-up of these noble gases during operation.

Here's a long technical paper (via
@pretentiouswhat): www-pub.iaea.org/MTCD/Publicati…

Talking with @CherylRofer this morning though, it sounds like this kind of problem, while... problematic... is not an emergency in-and-of-itself... curious what other nuclear tweeps think (@nuclearkatie wanna weigh in?)

@CherylRofer @nuclearkatie Further indications of whether this is serious may come from either @iaeaorg or @ctbto_alerts. China is required to report serious incidents to the IAEA. The CTBTO has noble gas monitoring stations throughout the region.

@CherylRofer @nuclearkatie @iaeaorg @ctbto_alerts Well there you go, @nuclearkatie also seems to think current data indicates failed fuel elements:

https://twitter.com/nuclearkatie/status/1404443221221126153

So bottom line: indications of something happening in Taishan, but the current available data does not yet indicate an emergency.

And as a coda for those of us in the biz: HOW CONFUSING IS IT THAT THE CHINESE SAFETY AGENCY GOES BY NNSA?! IS THAT SOME SORT OF TROLL?

UPDATE: Wire reports indicate that there is a fuel issue, as speculated in this thread.

reuters.com/article/china-…

FURTHER UPDATE: @ctbto_alerts tells me the International Monitoring System has not reported any unusual radionuclide detections thus far.

(cc @ferencdv)

@ctbto_alerts @ferencdv I'd argue that's consistent with the Chinese NNSA readings at the top of this thread. The low levels seen around the plant probably wouldn't show up at the IMS stations (which are located much further away).

@ctbto_alerts @ferencdv PM UPDATE: Just piling on this thread, it seems those NNSA numbers at the top may be natural background (thanks to @maesetote again for pointing that out). So not an indication of a leak (though still possible).

EDF has said that there was a build up of Krypton and Xenon.

The Reuters story says that the issue is with "fuel rods and seals".

Not clear if that means the sealed endcaps of the fuel rods, or maybe the seals around control arms or some other mechanism in the core?

In any event, here's a nice IAEA summary of ALL THE THINGS that can go wrong with fuel rods:

www-pub.iaea.org/MTCD/Publicati…

Buried in there is a rep of a previous prob with the welding on end caps of French fabricated rods...

asn.fr/content/downlo…

But of course, this is just background. We have very few details about what's actually happened at Taishan 1. But just to emphasize again: the information we do have doesn't point to a big crisis right now.

FINAL UPDATE FOR NOW: @iaeaorg has responded that they are aware of reports and in touch with Chinese counterparts. As of now, the agency has "no indication that a radiological incident occurred."