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Investigations -- where to place in article

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Made Its Own Section

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 Done I don't think the investigations should be under "Consequences"--which should focus on effects to living beings, the environment, structures, infastructure, etc. However, I don't think it should have been under "Criticisms" either. Investigations are supposed to be independent. I would put it in its own category. I did look at the two U.S. shuttle disasters and was surprised neither had an investigation section. It would be worth looking at some of the other disasters like the recent collision of the ship destroying bridge in Baltimore or the ship that grounded and blocked the Suez Canal--to see how those articles placed the investigation section. --David Tornheim (talk) 20:26, 3 June 2024 (UTC)[reply]

I appreciate this remark and would support a move to its own section. I checked out 2021 Suez Canal obstruction which does not have a section on investigations and Francis Scott Key Bridge collapse which put the investigation section under the collapse which I do not think is great. I also looked at Chernobyl disaster which has its own investigation section although I don't think it is particularly well done either. None of these are GA.
I did look at Space Shuttle Challenger disaster which has its own section on Reports which would be equivalent to an investigation section here. To me, that is sufficient guidance. Czarking0 (talk) 22:12, 3 June 2024 (UTC)[reply]

I have taken this action Czarking0 (talk) 02:22, 26 June 2024 (UTC)[reply]

What to Have in Section

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There are a lot of reports/investigations related to this accident. If all of them are covered here this will be the longest article. With that in mind, I propose that this section only cover particularly notable investigations into subjects that are the main topic of other sections.

With this in mind, I propose to delete the below text. I think this investigation is no longer notable primarily because there have been more recent investigations that have better methodology for assessing the current state of the fuel. For example the muon tomography myself and other users have mentioned. Those are mentioned (or at least should be mentioned) in the sections detailing the events of each unit. Furthermore, I do not think it is worthwhile to include those studies into these section as those studies a primarily part of the cleanup effort and are investigating the accident itself.

TEPCO released estimates of the state and location of the fuel in a November 2011 report.[48] The report concluded that the Unit 1 RPV was damaged during the accident and that "significant amounts" of molten fuel had fallen into the bottom of the PCV. The erosion of the concrete of the PCV by the molten fuel after the core meltdown was estimated to stop at approx. 0.7 m (2 ft 4 in) in depth, while the thickness of the containment floor is 7.6 m (25 ft). Gas sampling carried out before the report detected no signs of an ongoing reaction of the fuel with the concrete of the PCV and all the fuel in Unit 1 was estimated to be "well cooled down, including the fuel dropped on the bottom of the reactor". Fuel in Units 2 and 3 had melted, however less than in Unit 1. The report further suggested that "there is a range in the evaluation results" from "all fuel in the RPV (no fuel fallen to the PCV)" in Unit 2 and Unit 3, to "most fuel in the RPV (some fuel in PCV)". For Unit 2 and Unit 3, it was estimated that the "fuel is cooled sufficiently". According to the report, the greater damage in Unit 1 (when compared to the other two units) was due to the longer time that no cooling water was injected in Unit 1. This resulted in much more decay heat accumulating, as for about 1 day there was no water injection for Unit 1, while Unit 2 and Unit 3 had only a quarter of a day without water injection.[48]

Action taken Czarking0 (talk) 23:23, 23 July 2024 (UTC)[reply]

NAIIC Page Numbers

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The NAIIC report is currently cited as FN72. This needs page numbers for each time it is cited. This would be a great thing for a newcomer to do. Czarking0 (talk) 22:41, 5 July 2024 (UTC)[reply]

Action taken Czarking0 (talk) 22:01, 17 August 2024 (UTC)[reply]

Status of Each Unit Since the accident

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Each unit X subsection in the Accident section makes an abrupt shift from what happened during the accident to updates with more recent info. Most of the those updates are actually out of date now. Overall these sections should really just cover what happened at each unit during the accident. However, I do think the reader would appreciate a quick summary of what the status is now.

Maybe the better middle ground is to just state that there are various construction projects happening at Daiichi. Which will support the safe removal of all the fuel from the reactors and these projects are scheduled to be completed by 2031? I would appreciate some editors weighing in on this.

Sources: https://www.tepco.co.jp/en/hd/decommission/project/roadmap/index-e.html https://www.tepco.co.jp/en/hd/decommission/progress/removal/unit1/index-e.html

I will describe the changes I make to each section below

Unit 1

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Here is a quote of what is at the end of the unit one section now which I think is basically irrelevant. I think this could make good info for the Fukushima disaster cleanup page.

Deleted:

In February 2015, TEPCO started the muon scanning process for Units 1, 2, and 3. With this scanning setup, it was possible to determine the approximate amount and location of the remaining nuclear fuel within the RPV, but not the amount and resting place of the corium in the PCV. In March 2015 TEPCO released the result of the muon scan for Unit 1 which showed that no fuel was visible in the RPV, which would suggest that most if not all of the molten fuel had dropped onto the bottom of the PCV – this will change the plan for the removal of the fuel from Unit 1.

Recommend that these sections are deleted or scaled back as the info is basically out of date and somewhat out of scope. However, I wanted to wait until better info is added:

Subsequent analysis in November suggested that this extended period without cooling resulted in the melting of the fuel in unit 1, most of which would have escaped the reactor pressure vessel (RPV) and embedded itself into the concrete at the base of the PCV. Although at the time it was difficult to determine how far the fuel had eroded and diffused into the concrete, it was estimated that the fuel remained within the PCV.[48] In November 2013, Mari Yamaguchi reported for Associated Press that there are computer simulations that suggest that "the melted fuel in Unit 1, whose core damage was the most extensive, has breached the bottom of the primary containment vessel and even partially eaten into its concrete foundation, coming within about 30 cm (1 ft) of leaking into the ground" – a Kyoto University nuclear engineer said with regard to these estimates: "We just can't be sure until we actually see the inside of the reactors."[49]

I updated this to cover the fact that fuel is still in the SFP, and there is a (long) plan in place for getting it out. However, I would appreciate some help understanding/summarizing the state of the fuel in/around the PCV as this report was a little too technical for me to feel comfortable summarizing it. One of the main points of confusion I have is: does all the fuel debris remain contained in the concrete base of the PCV or did some fuel melt down to the ground?

Here are the sources I was looking into. https://www.iaea.org/sites/default/files/23/04/events-and-highlights-february-2023.pdf https://www.tepco.co.jp/en/hd/decommission/information/committee/pdf/2024/roadmap_20240425_01-e.pdf https://apnews.com/article/japan-fukushima-daiichi-radioactive-water-release-75becaaf68b7c3faf0121c459fdd25af

Unit 2

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Removing this section in favor of the Fuel Removal summary

In February 2017, six years after the accident, radiation levels inside the Unit 2 containment building were crudely estimated to be about 650 Sv/h.[1] The estimation was revised later to 80 Sv/h.[2] These readings were the highest recorded since the accident occurred in 2011 and the first recorded in that area of the reactor since the meltdowns. TEPCO released images taken inside unit 2 by a remote-controlled camera that show a 2 m (6.5 ft) wide hole in the metal grating under the pressure vessel in the reactor's primary containment vessel,[3] Later analysis indicated a meltdown/melt-through had occurred, through this layer of containment.[4][5] Ionizing radiation levels of about 210 sieverts (Sv) per hour were subsequently detected inside the Unit 2 containment vessel.[6] Undamaged spent fuel assembly typically has a surface dose rate of over 100 Sv/h, ten years after removal from a reactor.[7]

Unit 3

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The article currently talks about simulations of the melt into the concrete there is not reliable source for this so I am not sure what to make of this claim. TEPCO diagrams don't make this seem true, but they obviously have vested interests.

"Within the first three days of the accident the entire core content of reactor 3 had melted through the RPV and fallen to the bottom of the PCV." This claim as it is currently written almost certainly cannot be verified or is at least contestable. First of all, the source is highly technical and relies on simulations which even the source expresses doubt in and on remote neutron measurement. Remote neutron measurement is not an established way of assessing PCV breaches and this source is clearly academic and speculative. Second, the 2017 muon study indicates there was doubt about if there is still fuel in the RPV. It certainly would not be neutral to present "the entire core ... melted through the RPV". I propose that the prose is updated to summarize the diagram of unit 3 at the bottom of the 2017 muon study.

Updated about the fuel rods being removed. Stated decommissioning timeline for removing the debris. Boldly implemented the suggestion I explained above.

Unit 4

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Just added that the rods were removed. Not much more to say here.


Czarking0 (talk) 23:31, 22 June 2024 (UTC)[reply]

I made a "Fuel Removal" subsection under Remediation and recovery to consolidate the info I discussed in this section as what is here clearly does not belong in descriptions of what occurred during the accident. Czarking0 (talk) 17:48, 24 July 2024 (UTC)[reply]

Hydrogen Gas in Unit 4 Explosion

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There is already some existing talk page discussion about what the source of the hydrogen gas for the unit 4 explosion was see Archieve 9 for more background.

Here I wanted to point out that "The explosion was later found to be caused by hydrogen passing to unit 4 from unit 3 through shared pipes." is not a neutral representation of the source. The source clearly shows there was no consensus on the cause of the hydrogen gas and in that analysis the unit 3 venting was just one theory. However, I do think the spirit of claim is correct but additional sources are needed. Czarking0 (talk) 06:15, 23 June 2024 (UTC)[reply]

Changed from "later found" to "likely" Czarking0 (talk) 17:53, 24 July 2024 (UTC)[reply]

Radionuclide release sources and claims

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The source for this claim is highly technical and it is not clear that it verifies the claims in the quoted paragraph below. I think this constitutes WP:OR or at least needs additional sources to verify all the claims. Given the single source it is not clear to be that the claims are also notable. There is a lot of published research about the accident, but a single publication in a second-rate journal cannot be used as the standard for notability or this would be the longest page on WP.

Once released into the atmosphere, those which remain in a gaseous phase will simply be diluted by the atmosphere, but some which precipitate will eventually settle on land or in the ocean. Thus, the majority (90~99%) of the radionuclides which are deposited are isotopes of iodine and caesium, with a small portion of tellurium, which are almost fully vaporized out of the core due to their low vapor pressure. The remaining fraction of deposited radionuclides are of less volatile elements such as barium, antimony, and niobium, of which less than a percent is evaporated from the fuel.

[8] Czarking0 (talk) 15:37, 23 June 2024 (UTC)[reply]

This claim from oldid 1174678910 is similar

The predominant mechanism by which fission products can leave the core during core melt is through vaporization, thus only relatively volatile nuclides mix with the vaporized coolant and can be transported by the flow of gas. This gas can then exit the RPV and into the PCV through small leak paths in imperfections in the RPV, but in a situation in which the RCIC is used, this gas flows through the RCIC system and into the suppression pool, where some of the vaporized or suspended fission products are condensed or captured (scrubbed) by the SC, although some remainder (notably, radioactive noble gasses) will remain vaporized or suspended inside of the PCV. From the PCV, similar to the RPV, some small quantity inevitably leaks through small imperfections in the structure, but the predominant designed path for the escape of suspended radionuclides is through venting of the PCV where they are dispersed by the vent stack. However, if the PCV is compromised, the gas will be released directly into the secondary containment, and the potential loss of the SC function would also increase the concentration of unwanted fission products in the gas.

This is probably supposed to be from section 4.1 of the IAEA source FN9. However, it really says nothing like this and this seems like WP:OR or at least not verifiable with the sources. Therefore I will remove.

Czarking0 (talk) 20:52, 24 July 2024 (UTC)[reply]


References

  1. ^ "High radiation readings at Fukushima's No. 2 reactor complicate robot-based probe". The Japan Times. 10 February 2017. Archived from the original on 15 February 2017. Retrieved 11 February 2017.
  2. ^ 東電 2号機 格納容器の放射線量を大幅訂正 (in Japanese). NHK. 28 July 2017. Archived from the original on 27 July 2017. Retrieved 28 July 2017.
  3. ^ "Highest radiation reading since 3/11 detected at Fukushima No. 1 reactor". The Japan Times. 3 February 2017. Archived from the original on February 6, 2017.
  4. ^ "Tepco surveys interior of unit 2 containment vessel". World Nuclear News. 19 January 2018. Retrieved 20 January 2018.
  5. ^ Cite error: The named reference asahi-20180120 was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference ng-scorpion-210sv was invoked but never defined (see the help page).
  7. ^ "Backgrounder on Radioactive Waste". United States Nuclear Regulatory Commission. 2024-01-26. Retrieved 2024-06-22.
  8. ^ Saegusa, Jun; Kikuta, Yasuaki; Akino, Hitoshi (July 2013). "Observation of gamma-rays from fallout collected at Ibaraki, Japan, during the Fukushima nuclear accident". Applied Radiation and Isotopes. 77: 56–60. Bibcode:2013AppRI..77...56S. doi:10.1016/j.apradiso.2013.02.018. ISSN 0969-8043. PMID 23524231.
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Lawsuits and Legal Settlements are problematic because they can't be scientifically proven to be tied to the radiation exposure. Radiation Scientist James Conca pointed this out in a 2018 Forbes article that the man who developed Cancer likely did not receive it from Fukushima, and while his article is biased, scientifically speaking his point stands because it is more likely the man developed cancer due to secondhand smoke and that ionizing radiation from Nuclear accidents doesn't have a strong correlation with the type of Lung Cancer he developed (it's also overlooked that he exceeded his dose earlier in his career as well if one does want to attribute it to radiation, so it may be a non-Fukushima radiation-related death). The same can be said of the Thyroid cancer patients; I just updated the radiation related illnesses section with some recent studies including one that suggests in the interest of unbiased and neutral language that the UN and Japanese Government may be causing underreporting of Thyroid cancers (I couldn't find a 2024 follow up on this so there seems to not be any new information yet), but the overall scientific consensus remains that there is no evidence of a dose-response relationship due to ionizing radiation, and that the cancers are likely being detected via the screening effect.

MMFA (talk) 21:56, 13 August 2024 (UTC)[reply]

I second the spirit of this suggestion. However this could be controversial. Additionally, even if you have the right spirit I think it will be hard to get it right given that it is the lead to a complex topic. I encourage you to boldly attempt to make this revision. We shall see what others think. Personally, I had a similar idea a while back and then never got around to editing the lead. Czarking0 (talk) 01:16, 14 August 2024 (UTC)[reply]

GA Review

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This review is transcluded from Talk:Fukushima nuclear accident/GA1. The edit link for this section can be used to add comments to the review.

Nominator: Czarking0 (talk · contribs) 22:15, 17 August 2024 (UTC)[reply]

Reviewer: IntentionallyDense (talk · contribs) 01:01, 14 October 2024 (UTC)[reply]


This is going to be a big one but I'll review it. I'm going to start by doing an image review, then check sources, then prose. IntentionallyDense (talk) 01:01, 14 October 2024 (UTC)[reply]

Thank you so much I know this article is dense but I think it is a very important topic. I got all the easy points you made. I am unfortunately very busy in my personal life right now but I will get to everything in the next couple days. Czarking0 (talk) 17:35, 16 October 2024 (UTC)[reply]
Sounds good. I’m all good if it takes you time as long as you communicate that with me (like you’ve done)! IntentionallyDense (talk) 18:38, 16 October 2024 (UTC)[reply]
This is a really good review Czarking0 (talk) 15:47, 23 October 2024 (UTC)[reply]
Thank you. This is a really good article! IntentionallyDense (talk) 19:08, 23 October 2024 (UTC)[reply]
Rate Attribute Review Comment
1. Well-written:
1a. the prose is clear, concise, and understandable to an appropriately broad audience; spelling and grammar are correct. IntentionallyDense (talk) 22:01, 15 October 2024 (UTC)[reply]
1b. it complies with the Manual of Style guidelines for lead sections, layout, words to watch, fiction, and list incorporation. IntentionallyDense (talk) 22:01, 15 October 2024 (UTC)[reply]
2. Verifiable with no original research, as shown by a source spot-check:
2a. it contains a list of all references (sources of information), presented in accordance with the layout style guideline. IntentionallyDense (talk) 01:55, 14 October 2024 (UTC)[reply]
2b. reliable sources are cited inline. All content that could reasonably be challenged, except for plot summaries and that which summarizes cited content elsewhere in the article, must be cited no later than the end of the paragraph (or line if the content is not in prose). See comments below. IntentionallyDense (talk) 01:55, 14 October 2024 (UTC)[reply]

I've spot checked about 1/4 of the sources and found no issues. Great work! IntentionallyDense (talk) 02:54, 23 October 2024 (UTC)[reply]

2c. it contains no original research. per above. IntentionallyDense (talk) 01:55, 14 October 2024 (UTC)[reply]
2d. it contains no copyright violations or plagiarism. IntentionallyDense (talk) 02:54, 23 October 2024 (UTC)[reply]
3. Broad in its coverage:
3a. it addresses the main aspects of the topic. See comments below. IntentionallyDense (talk) 02:54, 23 October 2024 (UTC)[reply]
3b. it stays focused on the topic without going into unnecessary detail (see summary style). IntentionallyDense (talk) 22:01, 15 October 2024 (UTC)[reply]

While this article is very long I think it is appropriate considering the topic. IntentionallyDense (talk) 02:54, 23 October 2024 (UTC)[reply]

4. Neutral: it represents viewpoints fairly and without editorial bias, giving due weight to each. See comments below. IntentionallyDense (talk) 02:54, 23 October 2024 (UTC)[reply]
5. Stable: it does not change significantly from day to day because of an ongoing edit war or content dispute. IntentionallyDense (talk) 01:55, 14 October 2024 (UTC)[reply]
6. Illustrated, if possible, by media such as images, video, or audio:
6a. media are tagged with their copyright statuses, and valid non-free use rationales are provided for non-free content. IntentionallyDense (talk) 01:55, 14 October 2024 (UTC)[reply]
6b. media are relevant to the topic, and have suitable captions. See comment below. IntentionallyDense (talk) 01:55, 14 October 2024 (UTC)[reply]
7. Overall assessment. I'm going to place this on hold since there is several unsourced sections of text and the citations need to be edited to be consistent (either use templates or don't, either use rp or sfn) and I have a feeling that may take awhile. IntentionallyDense (talk) 04:35, 14 October 2024 (UTC)[reply]
Getting to all your points in due; however, I wanted to point out that citation format sfv vs rp, etc is not a GA criteria. It is for FA Czarking0 (talk) 15:55, 16 October 2024 (UTC)[reply]
It is because Criterion 1 requires compliance with MOS:LAYOUT, and criterion 2 also requires compliance with the MOS:LAYOUT section MOS:REFERENCES. It says:
“Editors may use any citation method they choose, but it should be consistent within an article.” IntentionallyDense (talk) 18:23, 16 October 2024 (UTC)[reply]
I think I now have all the sfn converted to rp and all refs use a template Czarking0 (talk) 20:21, 18 October 2024 (UTC)[reply]
Sounds good, I'll continue with my review. IntentionallyDense (talk) 20:32, 21 October 2024 (UTC)[reply]

The lead

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Background

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  • Zircaloy can be oxidized by steam to form hydrogen gas or by uranium dioxide to form uranium metal. I'm a little unsure about what you mean here. do high temperatures also create uranium metal or is that the uranium dioxide. If it is the former is that relevant to the article? IntentionallyDense (talk) 03:30, 22 October 2024 (UTC)[reply]
    My understanding is that both these reactions would be contributing to the meltdown. The high temp, high pressure steam from emergency cooling systems should oxidize the components. This is bad because it weakens the material. The source calls out the exothermic nature of this but how important that heat is compared to the reactor itself would require expert analysis. FN29 seems to indicate it is not negligible.
    The second reaction very important. This is the primary reaction that causes the meltdown/ melt-through. As the uranium oxidizes the vessel it will melt/ break the zircaloy and eventually escape. This is part of how the fuel ends up outside of the containment.
    Now the source for this section is not actually about Fukushima at all and it just background info on reactor chemistry so I am not sure how to edit the article. Maybe the summary sentence is "these reactions are important processes in how a zircaloy cladding fails during meltdown."
    To me this just boarders on super technical information that WP is not super well suited for. I would also consider deleting this materials section and seeing where else in the article this info might be relevant. Czarking0 (talk) 16:56, 23 October 2024 (UTC)[reply]
    Your explanation makes sense I just think I stared at the words for a little to long. I'm fine with leaving it as is tbh. IntentionallyDense (talk) 04:11, 24 October 2024 (UTC)[reply]
  • DC power was needed to remotely control it and receive parameters and indications and AC power was required to power the isolation valves. Acronyms should be spelt out in full when first used. IntentionallyDense (talk) 03:30, 22 October 2024 (UTC)[reply]
     Not done doing acronyms at the end Czarking0 (talk) 16:59, 23 October 2024 (UTC)[reply]

Accident

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Consequences

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Investigations

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Remediation and recovery

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Prior warning

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Overall

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