Talk:Comparison of the Chernobyl and Fukushima nuclear accidents

Maximum level of radiation detected?

I'm rather surprised that the unit used there was in mSv. A "level of radiation" generally means a dose rate and is measured in sieverts per time unit. Furthermore, where does the 200Sv figure for Tchernobyl comes from? In any case, I'm switching to mSv/h for Fukushima. Regards, ConradMayhew (talk) 12:03, 7 January 2012 (UTC)

For acute effects in biological systems and for doses to non living things, the Gray should be used.Dr Mark Foreman (talk) 21:04, 7 February 2013 (UTC)

Time until containment

What about the fact that in Chernobyl, general containment was achieved within a week, whereas the Fukushima reactors are both not contained, still critical, and left blowing radiation into the atmosphere after more than a year? --79.193.62.185 (talk) 05:03, 17 March 2012 (UTC)

A lot depends on your exact definition of containment. I know little about Fukushima, but at Chernobyl, containment of solids happened within, perhaps, 10 minutes of the explosion. The "fire" was declared out within two weeks. Gaseous and light effluents escaping into the atmosphere probably occurred for months; they were still dropping materials into the reactor by helicopter in October, when the helicopter accident happened. Odd German tourists are digging up pieces of what is probably fragments of graphite in the turf to the current day. The reactor case itself is mainly empty; most of the 80% of the fuel and graphite eventually found its way into the basement of the plant has molten corium and eventually froze there. SkoreKeep (talk) 02:50, 26 February 2013 (UTC)

Need to add: General containment of the Fukushima reactors, at least in the sense that Chernobyl #4 was contained) has never been an issue; none of the reactors at Fukushima were critical (running fission processes) since the alarm from the earthquake was received, a half-hour before the tsunami, and with the possibly, though not probable, exception of the two hydrogen blasts, no radiation has been "blowing into the atmosphere" at Fukushma; the chief worry at this point is waste water draining into the Pacific Ocean. SkoreKeep (talk) 15:53, 20 July 2015 (UTC)

Iodine-equivalent Bq

Some of the "radiation released" numbers are in so-called "Iodine-equivalent" Bq and some in real Bq (In general the total radiation amounts are Iodine-equivalent, but it's hard to tell for some), this creates quite some confusion. It also seems some of the references cited are confused about this distinction, making it hard to check which is which. (88.115.80.54 (talk) 03:52, 15 November 2012 (UTC))

Misleading numbers

The numbers for "Radiation released" are very misleading. For Chernobyl it seems to be a total, for Fukushima it is the number from one month only (and since then afaik huge amounts of radiation continued to leak). — Preceding unsigned comment added by 213.47.143.43 (talk) 09:56, 14 April 2013 (UTC)

Be bold to update the table when substantial evidence is available. SkoreKeep (talk) 00:32, 6 September 2014 (UTC)

Damage to reactor structures

A section comparing the damage to the reactor vessel and secondary containment structures would be relevant. I.e. the chernobyl reactor basically disintegrated, and the fukushima reactor vessel? has it been breached or not? this is an important question to answer and should be answered here. — Preceding unsigned comment added by 76.167.41.198 (talk) 05:25, 21 September 2013 (UTC)

The latest I read is that the reactor vessel was pierced on only one of the reactors, and the corium was expected to have melted into the concrete floor to within a foot of it depth, where it has essentially frozen in place. This has to be at least partially speculative at this point. SkoreKeep (talk) 00:30, 6 September 2014 (UTC)

suggested improved numbers

The 4 GW and 4.7 GW rating is for the entire complex, it may make some sense to break out the MW capacity of the damaged units, as well.

Chernobyl Units 2-4 are basically intact.

Fukushima 5,6 are relatively undamaged.--Patbahn (talk) 02:58, 10 February 2014 (UTC)

Fuel weights

Where did those number come from? 180 tons for Chernbyl, 1600 for Fukushiima? Even allowing for 4 times the reactors at Fukushima, it seems awfully high. For Chernobyl, I computed 245 metric tons (1661 assemblies, 137.5 kg U per assembly). If anyone has the weight of U per Fukushima assembly (in the reactor and in the pool, if not the same) I'd really appreciate it.

OK, for Fukushima it includes the weight of the uranium in the four reactor's cooling pools as well as the uranium in the central pool, in another building. Reactor #4 had no fuel in it at the time of the accident; it's next fuel load was in its pool, for some reason. I also understand the fuel assemblies weighed about 400 kg each, of which 183.3 kg was uranium. SkoreKeep (talk) 00:25, 6 September 2014 (UTC)

radiation released

Is it worthwhile breaking out the radio-isotopes released by isotope?

The I-131 release numbers are different from the Cesium and Trans-uranics.

It may need it's own table to be listed.--108.18.177.140 (talk) 03:14, 18 February 2015 (UTC)

It certainly could be, if reliable figures are available. SkoreKeep (talk) 15:58, 20 July 2015 (UTC)

Does it even mean anything for amount of radiation released towards the atmosphere? It seems like just giving the atmosphere a big X-ray, who cares? Or does PBq also measure radioactive **material**? (something that seems to matter because it then gets into food etc. and releases radiation into tissue) Blargg (talk) 10:14, 25 April 2016 (UTC)

There is no propert distinction between the mode of release, soil, atmospheric, only sea. Also noble gases are totally skipped; Arnie Gudernsen mentioned they were x3 than Chernobyl: youtu.be/snBzZnMNNfg?t=38m51s Sperxios (talk) 23:54, 8 June 2016 (UTC)

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Fuel weights (continued)

The Chernobyl reactor 4 fuel weight needs a second look. I understand the calculation (fuel bundle weight x total number of bundles = total fuel load) but that number isn't matching up properly with what's out there.

99% of sources and literature speak of only 180-200 tons loaded in the reactor at the time of the accident. The very few number of sources that speak of the ~240 ton fuel load seem to derive from this bundle weight calculation. In fact the top three search results of 240-250 tons all derive from the info on this wikipage. (The top hit being this page). All the articles and journals I found speak of the 180 ton number. I would have suspected some confusion due to conversion from Russian weight units but the Soviets adopted the metric system in the 1920's.

The most logical answer seems to be that the core wasn't 100% loaded at the time of the accident.

(Sources)

• https://books.google.co.uk/books?id=yaJTAgAAQBAJ&pg=PT233&lpg=PT233&dq=chernobyl+180+tons&source=bl&ots=z-voS7wk3m&sig=eNBSlAJJPI3jCbotZEOrKAeGGuE&hl=en&sa=X&ved=0ahUKEwiq97zWzKrMAhUGrxoKHQV6D3sQ6AEIRjAG#v=onepage&q=chernobyl%20180%20tons&f=false

• http://www.sciencemag.org/news/2011/03/how-much-fuel-risk-fukushima

• http://www.themoscowtimes.com/sitemap/free/2000/12/article/chernobyl-workers-find-nuclear-fragment/256996.html — Preceding unsigned comment added by 86.191.18.105 (talk) 23:41, 25 April 2016 (UTC)

Comparison is misleading as only FDI & CRN are listed

Comparison should inclue at least 3 mile island — Preceding unsigned comment added by 93.20.250.196 (talk) 12:45, 20 September 2016 (UTC)

Actual maximum level of radiation detected

http://voices.nationalgeographic.org/2017/02/22/after-alarmingly-high-radiation-levels-detected-what-are-the-facts-in-fukushima/

A few days after the telescoping-arm investigation, a small-tracked cleaning robot with a high-pressure water nozzle and a scraper was inserted. This operated for 2 hours before the radiation had degraded the camera too much to continue. Neither the telescoping unit nor the cleaning robot had an actual radiation detector, and radiation levels were inferred from camera noise and degradation of the cameras. TEPCO’s first announcement was that radiation levels were estimated to be as high as 530 Sv/hour; the succeeding estimate was over 600 Sv/hr. Either would be fatal to a human after a few minutes’ exposure. Finally, on Feburary 16, Tepco inserted a second robot into the reactor. This one is called the “Scorpion” because it has a folding “tail” containing powerful lighting and a camera. It operated well for about 30 minutes before becoming immobile, but was able to obtain about 6 hours of video images as well as better radiation measurements, which showed maximum levels of about 210 SV/hr. While this is lower then the previous estimates, it is also considered more accurate and within an order of magnitude. It would also be fatal to humans after a few minutes’ exposure.

https://www.toshiba.co.jp/about/press/2015_06/pr3001.htm

The robot is approximately 54cm long and 9cm high and wide, and is equipped with two cameras, LED lights, a radiation dosimeter and a thermometer. Remotely operated by a wired cable, the robot will enter the PCV along a pipe approximately 10cm in diameter.

This should settle the argument once and for all. Garzfoth (talk) 05:36, 19 November 2017 (UTC)

Thank you for the detail. Really nice insight. However, comparing radiation level 6 years after incident with number measured immediately after meltdown is misleading. Maybe it's better to change the row title. Oceangai (talk) 07:28, 19 November 2017 (UTC)

How is the row title misleading? It is quite literally the "maximum level of radiation detected", just as the row's name says. The text within the row specifies at which point and where the measurement was made. It would certainly be nice to have earlier data, and it would also be nice to have data from Units 1 & 3, but unfortunately the only data we have right now is from Unit 2 six years after the incident. Once data becomes available from Units 1 & 3, that can be added as well, but there's no way to obtain earlier data for any of the units, so we have to make the best of what's available. Garzfoth (talk) 13:09, 19 November 2017 (UTC)

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