Major breakthrough on nuclear fusion energy - BBC News

[leadeater]

On 2/15/2022 at 9:52 PM, Imbadatnames said:

You’re literally using Wikipedia dude 

Wikipedia with/has citations, WNA and IAEA, along with other sources. I post using whatever is concise and to the point with the information explained as simply as possible or convenient for others to find.

 

I would rather post the facts and be branded as a "Wikipedia user" than post false/incorrect/misleading information (obviously I have posted all 3 of these at some point as a member of this forum and in life in general, nobody is perfect).

 

I mean you can throw the whole Wikipedia line all you like but that does not actually change the facts of the matter and that you were wrong. You can choose which ever source you like, the official record is 11 TEPCO reactors were shutdown immediately after the earthquake because the ground movement was either above S1 (not that bad but still requires shutdown) or S2 (bad and above designed upper limits).

 

Also for that matter the Japan and TEPCO safety designs and ground prep along with the ground movement thresholds are well above most other countries, twice as high as many others, because of where the country is located and local risks. France for example does not need to go to the same extent. There is no single unified "standard" and "rules" for those specific things because the actual standards and guidelines call for taking in to account local risk factors i.e. you don't build a 20m sea wall in the middle of a desert.

[leadeater]

19 hours ago, IPD said:

Wikipedia is a great, simplistic coalescence of information that comes from other sources.  This makes it easier to give one easy-to-understand reference to those who can't be bothered to research things in depth on their own.  Are you going to cite term papers from it?  No.  Is it useful for pointing out basic facts about Windscale when some people clearly are devoid of even a modicum of factual background information?  You bet.

Eh even at university level Wikipedia is perfectly fine for background research and for finding secondary and primary sources that you can cite. Most people that put information on Wikipedia for this type of thing are all highly educated and know how to cite, do cite and Wikipedia requires citations. You just don't actually cite Wikipedia itself in any of your papers, assignments etc.

 

As a student (and for myself a staff member) you get access to all the scientific journal databases and can pull up literally anything that has been published. I don't think an internet forum is the place for me to go login to one of those to find what is public record and documented widely. Seems a bit of a waste of time to me....

[IPD]

3 minutes ago, leadeater said:

Eh even at university level Wikipedia is perfectly find for background research and for finding secondary and primary sources that you can cite. Most people that put information on Wikipedia for this type of thing are all highly educated and know how to cite, do cite and Wikipedia requires citations. You just don't actually cite Wikipedia itself in any of your papers, assignments etc.

 

As a student (and for myself a staff member) you get access to all the scientific journal databases and can pull up literally anything that has been published. I don't think an internet forum is the place for me to go login to one of those to find what is public record and documented widely. Seems a bit of a waste of time to me....

100% agreed.  Probably why I got knocked down a few points on every term paper, because it was far easier for me to find/cite online than to utilize their rigid "source materials" that they wanted me to primarily utilize.  Nevermind that it is far easier to color outside the lines when you aren't rigidly forced into source material.  And if novel ideas/solutions are required, dogmatic adherence to particular sources won't cut it.

[wanderingfool2]

6 hours ago, Imbadatnames said:

It would be great if either plant actually met the international regs but both were 30+ years old at the time. 
 

You’re literally using Wikipedia dude 

Honestly, just stop.  LeadEater literally disproved the point you were trying to pull off as a fact, you don't get to pretend as if you were making another point.

 

Also, Wikipedia is a perfectly good starting source for references, too which you can use those sources appropriately.  e.g. Why should it matter if leadeater used wikipedia to get to the world-nuclear.org, whose director general has a phd in nuclear engineering (btw).  The person in charge there has experience and degrees that will beat out everyone on this forum

 

I find it funny, you keep calling people out for using Wikipedia and yet you miraculously claim as well that your "degree" means nothing in a prior argument.  If you do have a degree in anything related to Nuclear then I seriously worry about the future if you go after people for using a wiki as a starting point, while you are spitting out false facts or stats that have no bearing on a proper analysis (like ignoring deaths caused by fallout or contact because it's too hard to assess the correct number).

 

Anyways, I'm just going to stop responding to you, because there obviously isn't any point in responding as you are too much on your high horse with all the wrong information thinking you're correct to realize that you are wrong.

[leadeater]

4 hours ago, wanderingfool2 said:

Why should it matter if leadeater used wikipedia to get to the world-nuclear.org

Well it was actually the other way, I was on WNA first but it only said they were shutdown due to the earthquake, not specifically immediately in case the point was going to be argued. So I headed on over to Wikipedia because I knew it would have that information and a citation for it. I don't actually go to Wikipedia first when I see more credible sources ranked highly in a search.

[Forbidden Wafer]

About the wikipedia discussion: it can be fairly reliable for certain topics, but certainly isn't for a lot of other topics.

Also, it is not uncommon to see people saying they're citing a specific source and making up something that wasn't said.
Sometimes it is misinterpretation, sometimes it is ignorance, but sometimes it is absolutely on purpose.

As long as you check the primary source (NEVER trust secondary sources), it should be fine.

[IPD]

11 minutes ago, Forbidden Wafer said:

About the wikipedia discussion: it can be fairly reliable for certain topics, but certainly isn't for a lot of other topics.

Also, it is not uncommon to see people saying they're citing a specific source and making up something that wasn't said.
Sometimes it is misinterpretation, sometimes it is ignorance, but sometimes it is absolutely on purpose.

As long as you check the primary source (NEVER trust secondary sources), it should be fine.

True.  But citing peer-reviewed research journals is far too dry for most people.

[leadeater]

32 minutes ago, Forbidden Wafer said:

About the wikipedia discussion: it can be fairly reliable for certain topics, but certainly isn't for a lot of other topics.

Also, it is not uncommon to see people saying they're citing a specific source and making up something that wasn't said.
Sometimes it is misinterpretation, sometimes it is ignorance, but sometimes it is absolutely on purpose.

As long as you check the primary source (NEVER trust secondary sources), it should be fine.

All that matters is confidence in the information and accuracy, APA referencing standards can take a swift running jump off a cliff when it comes to internet forums 

 

Where the information comes from so long as it's accurate literally doesn't matter, like at all.

[Forbidden Wafer]

1 minute ago, IPD said:

True.  But citing peer-reviewed research journals is far too dry for most people.

While I agree most people won't look at it, if you cite it (even without reading it), other people can read it and comment if anything was badly reported.
News channels are notorious for getting things absolutely wrong.

[IPD]

4 hours ago, leadeater said:

All that matters is confidence in the information and accuracy, APA referencing standards can take a swift running jump off a cliff when it comes to internet forums 

 

Where the information comes from so long as it's accurate literally doesn't matter, like at all.

Shit, I wish I could have used APA for all my shit.

 

When I'm Emperor of the universe for a day, every citation format will pick 1 champion.  APA, MLA, Chicago Turabian, all of them.  All those champions get locked in a room, and only 1 leaves alive.  And only that format remains.

[mr moose]

11 hours ago, wanderingfool2 said:

I find it funny, you keep calling people out for using Wikipedia and yet you miraculously claim as well that your "degree" means nothing in a prior argument.  If you do have a degree in anything related to Nuclear then I seriously worry about the future

 

I wouldn't worry about the future,  anyone who says stuff like that isn't even applying for a job in nuclear anything let alone actually having an education, besides that all forum claims are largely bogus to a degree,  Here I have made a handy dandy reference to understand reality when people say:

 

I have a degree in...  =  I started reading for an online course.

I have owned several business =  I foolishly signed up for amway when I was a kid and now I consider that and working in a petrol station equivalent to running a business.

I have been in the industry for the last 15 years.  =  My dad owns a shop and I sweep the floors occasionally.

When I worked for *sizable company X*, I was a janitor for a subing firm who cleaned the toilets.

 

 

 

[Helpful Tech Witch]

16 hours ago, IPD said:

Are you going to cite term papers from it?  No. 

Ish

using Wikipedia as a great way to get actual research papers is great, scroll to the bottom and get loads of great citations to base your papers on

[CarlBar]

@leadeater Little late getting back into this. My understanding and what seems t be causing some confusion is that the flooding took out the stuff in the basement, thats i. That consisted of the backup generators and they're transformers and switching gear. The main substation up on a hill survived, but it's not designed to take in or output backup generator type voltages, which was why they couldn't easily bring in outside generators. And the long distance transmission lines where a mess due to the earthquake. But the rest of the plant machinery was AFAIK completely intact.

 

It's why the company got so much grief over where the positioned the backup generators. Citing them on higher ground would have averted the disaster despite the inadequate tsunami defences.

 

They should still have had better defences ofc and i don't agree with @Imbadatnames fully. But he is to the best of my knowledge right about some things.

 

 

@wanderingfool2 I can't speak to the building in question, but what i can say is that with proper design making a building that cna stand upto an earthquake isn't a matter of maybes. It's a straight physics problem and one where capable of solving with our current level of geophysics and material sciences understanding. Now making sure those are applied properly, thats a matter for regulation. I would point out however that the majority of Japan's plants came through the earthquake portion just fine. Some other bits of the grid infrastructure got knocked out, but the plants themselves, (and many other buildings elsewhere), did just fine.

 

And my point about the history of industrial accidents is you have to have measures in place to prevent accidents, but you also have to have measure in place to make the consequences of even multiple failures manageable. if you go around trying to design your reactors to never have a meltdown your going to have major releases because random chance will line up and cause them despite that. But by putting additional barriers into place to make releases even in the event of a full meltdown less likly, (and furthar barriers to make them smaller if they do occur). You can reduce the frequency at which major releases occur.

 

Fukashima had dodgy meltdown protection, but it's inability to prevent a major release, (due mainly to spent fuel pool locations and Hydrogen issues they had no real solution to), turned a mere meltdown, (yes i get the irony of that phrase), into a major radiation incident. 

[leadeater]

1 hour ago, CarlBar said:

@leadeater Little late getting back into this. My understanding and what seems t be causing some confusion is that the flooding took out the stuff in the basement, thats i. That consisted of the backup generators and they're transformers and switching gear. The main substation up on a hill survived, but it's not designed to take in or output backup generator type voltages, which was why they couldn't easily bring in outside generators. And the long distance transmission lines where a mess due to the earthquake. But the rest of the plant machinery was AFAIK completely intact.

 

The report specifically states the reactor buildings were flooded, the turbine rooms flooded causing damage, the switching rooms and also the switching room for the remote backup generators that are for if the reactor local ones don't work or for supplying general site power in the event of main grid AC loss. The remote generators were on high ground and not flooded, just their switching room.

 

I suggest you go read it in more detail because everything there leads me to conclude generating power with the main reactor fission was impossible due to the turbine room flood and damage as well switch room damage.

 

I'm unsure if the earthquake is actually to blame for the grid AC power loss, I have not read the large report itself only the WNA and IAEA summary reports. However I would strongly suggest the earthquake did not take out the power because the local ground movement was around magnitude 6.5 which is below Japan building code requirements. Much of the real devastation was due to the tsunami, that's what tore everything down.

 

[Edit]

Also I comment on this as a person living on the ring of fire who as experienced many ~6.0 earthquakes of all different depths and types, 6.5 isn't going to cause that much damage to the ground that would cause total main grid supply loss.

[Edit]

 

Basically I find it quite unlikely the earthquake damaged every single main supply, however the report also points to the fact that with all the reactors shutting down across the region there wasn't enough power capacity anyway and that also caused many ongoing issues days/weeks later as well. So intact or not backup generators would have been and were required due to that.

[CarlBar]

6 minutes ago, leadeater said:

The report specifically states the reactor buildings were flooded, the turbine rooms flooded causing damage, the switching rooms and also the switching room for the remote backup generators that are for if the reactor local ones don't work or for supplying general site power in the event of main grid AC loss. The remote generators were on high ground and not flooded, just their switching room.

 

I suggest you go read it in more detail because everything there leads me to conclude generating power with the main reactor fission was impossible due to the turbine room flood and damage as well switch room damage.

 

I'm unsure if the earthquake is actually to blame for the grid AC power loss, I have not read the large report itself only the WNA and IAEA summary reports. However I would strongly suggest the earthquake did not take out the power because the local ground movement was around magnitude 6.5 which is below Japan building code requirements. Much of the real devastation was due to the tsunami, that's what tore everything down.

 

Basically I find it quite unlikely the earthquake damaged every single main supply, however the report also points to the fact that with all the reactors shutting down across the region there wasn't enough power capacity anyway and that also caused many ongoing issues days/weeks later as well. So intact or not backup generators would have been and were required due to that.

 

Haven't really looked into it since a couple of years or so after the event so i'll defer to you on the report. My understanding is it was the high voltage transmission lines that came down that caused the issue with external power. Something like Nuclear plant cooling would be a priority item so lack of available power means little. When there too little power less esential items are taken off the grid to keep priority stuff operational.

[leadeater]

2 minutes ago, CarlBar said:

My understanding is it was the high voltage transmission lines that came down that caused the issue with external power.

Yes that is true, I just don't know specially which did it. In any case the tsunami was throwing literal large fishing boats in land crushing houses and tearing everything down, along with all the other debris, tsunami was going to most likely take it out if it hadn't already

[Curufinwe_wins]

6 hours ago, leadeater said:

Yes that is true, I just don't know specially which did it. In any case the tsunami was throwing literal large fishing boats in land crushing houses and tearing everything down, along with all the other debris, tsunami was going to most likely take it out if it hadn't already

For the record, plants were generally presumed to be shutdown *whenever* there is interuption to downstream distribution issues. It used to be assummed this was the safer action so that in case of a cascading issue, the reactor power was far less. Backup generators and similar are only for keeping RCS pumps running... the design of the plants was quite robust in safety sense, with a higher priority on earthquake resilience than tsunami because the height of tsunami needed to breach the sea wall was expected to be extremely unlikely. With that said, this earthquake was the 2nd or 3rd most energetic one known in human history. Oil refineries outside of tokyo literally blew up. Trillions of dollars of damage in the best engineered, most resilient country on earth.

 

Tbh I'm not sure why going through the causes of the disaster are that relevant.... The lessons learned have been incorporated world wide, and more have to do with post disaster decision making and emergency response preparedness than anything else. For example, PRA has decisively shown that evacuating the larger area was a mistake and killed many more than would have been exposed to even noticable radiation spikes. Secondly, plants are recognizing that in a variety of instances it may actually be safer to keep operating rather than go into a shutdown state as long as the grid can still recieve power. Not just for the plant itself, but also for the community as a whole. We saw this in a number of instances in the last couple years in the US, where in extreme weather, the overengineered nuclear plants requested and recieved approval to continue operating in weather that took almost everything else out, providing a critical lifeline to the affected areas.

 

Will check for public sources if need be: I am a Sr. Nuclear Materials Eng working for one of the largest nuclear firms in the world, and our Fukushima adjacent responses were incredibly detailed.

[leadeater]

@Curufinwe_wins tbh I've been waiting/wanting for you to comment lol

[CarlBar]

12 hours ago, leadeater said:

Yes that is true, I just don't know specially which did it. In any case the tsunami was throwing literal large fishing boats in land crushing houses and tearing everything down, along with all the other debris, tsunami was going to most likely take it out if it hadn't already

 

As i said the transmission lines for Fukashima ran straight down from higher ground, so they where immune to the Tsunami AFAIK. Unless all of Japans generating capacity was in Tsunami hit area's without the earthquake enough high ground grid infrastructure would have survived to feed power. Sounds like @Curufinwe_wins would know for sure.

 

What he said about being earthquake focused over Tsunami focused and believing until fairly close to the event that the Tsunami defences would handle anything that was possibble fits with the info i've heard.

[Curufinwe_wins]

1 hour ago, CarlBar said:

 

As i said the transmission lines for Fukashima ran straight down from higher ground, so they where immune to the Tsunami AFAIK. Unless all of Japans generating capacity was in Tsunami hit area's without the earthquake enough high ground grid infrastructure would have survived to feed power. Sounds like @Curufinwe_wins would know for sure.

 

What he said about being earthquake focused over Tsunami focused and believing until fairly close to the event that the Tsunami defences would handle anything that was possibble fits with the info i've heard.

I don't remember the specfic details of what was going on with the grid, but of the 11 reactors to be automatically tripped, all but Units 1-3 @ Daiichi were able to get grid or backup generators working. There 12 of 13 backup generators failed from the tsunami event. (Not exactly a small amount of redundancy built in, if the issue hadn't been systemic.)

 

It's also worth noting Japan suffered power issues for weeks after the event, not just from the loss of the nuclear plants, but also from other sources and a very unfortunate power grid situation. The west of the country, much of which was devastated by the earthquake and tsunamis runs on a completely different power infrastructure than the east of the country with only (particularly at the time) very low capacity to move power from one system to another.

 

 

For reference...

 

 

Please don't take this as suggesting there were no issues or anything... there definitely were lessons learned and particularly about how to respond decisively and rapidly to potential loss of supply station power (we call this ULOSSP in safety analysis space, and it is a standard criteria for evaluation)... but the evacuation process killed 1600 people, no radiation linked deaths have ever been demonstrated and current analysis shows lower than average cancer rates in the longitudal studies. Furthermore, across the scale of this disaster, almost 20,000 people lost their lives. It is literally the most economically costly natural disaster in human history, and the nuclear part of it is far less than 1/10th of that cost... the plants that failed were just south of Sendai on that map btw, which as you can imagine is an extraordinarily bad turn of events/fortune to have occurred location and severity wise...

[leadeater]

1 hour ago, CarlBar said:

What he said about being earthquake focused over Tsunami focused and believing until fairly close to the event that the Tsunami defences would handle anything that was possibble fits with the info i've heard.

For sure, I wasn't saying any different.

 

1 hour ago, CarlBar said:

As i said the transmission lines for Fukashima ran straight down from higher ground, so they where immune to the Tsunami AFAIK. Unless all of Japans generating capacity was in Tsunami hit area's without the earthquake enough high ground grid infrastructure would have survived to feed power. Sounds like @Curufinwe_wins would know for sure.

I know they come from high ground but they still have to run along site local ground level which is where I was thinking they would be damaged by the tsunami, since the reactor and turbine buildings were under water I figured so would the towers local to that area. Looking at the photos of the site it does appear that where they are located on the site is higher than where the reactors are, not too far back from the reactor and turbine rooms the site ground level is much higher (reinforcing walls etc as well).

 

Also all the main power lines within the facility site itself from the photos I looked at were all intact so I would have to assume based on that earthquake caused damage would likely be up along the hills/ranges and would be land movement/slippage due to the earthquake. So yea fair point earthquake could have damaged the main grid transmission lines, just not at the power facility site itself.

 

Anyway still doesn't actually change the likely result of just the tsunami alone which was my point, combination of both was not the specific reason because I simply have to come back to the simple issue that the turbine room was literally under water so if anyone could explain how a steam turbine generator could function under meters of water and debris I'd be all ears.

 

 

Note the water level. I just cannot realistically see how self reactor power generation and cooling would have been possible given the water pumps were damaged due to the water damage and all the critical building inundated with water.

 

So in my eye it's simply does not matter and it's disingenuous to say this only happened because the earthquake either damaged the main grid AC input/output to the reactors, or cause them to be shutdown, or both. It just doesn't matter, soon as that tsunami was on it's way at the height and volume of water Fukushima Daiichi was doomed.

 

@Curufinwe_winsWill likely be able to speak far more about it if actually possible or wishes to, but simply blaming this on both disaster events happening and so close together just doesn't wash with me, at all. Lame pun intended.

[Curufinwe_wins]

47 minutes ago, leadeater said:

For sure, I wasn't saying any different.

 

I know they come from high ground but they still have to run along site local ground level which is where I was thinking they would be damaged by the tsunami, since the reactor and turbine buildings were under water I figured so would the towers local to that area. Looking at the photos of the site it does appear that where they are located on the site is higher than where the reactors are, not too far back from the reactor and turbine rooms the site ground level is much higher (reinforcing walls etc as well).

 

Also all the main power lines within the facility site itself from the photos I looked at were all intact so I would have to assume based on that earthquake caused damage would likely be up along the hills/ranges and would be land movement/slippage due to the earthquake. So yea fair point earthquake could have damaged the main grid transmission lines, just not at the power facility site itself.

 

Anyway still doesn't actually change the likely result of just the tsunami alone which was my point, combination of both was not the specific reason because I simply have to come back to the simple issue that the turbine room was literally under water so if anyone could explain how a steam turbine generator could function under meters of water and debris I'd be all ears.

 

 

Note the water level. I just cannot realistically see how self reactor power generation and cooling would have been possible given the water pumps were damaged due to the water damage and all the critical building inundated with water.

 

So in my eye it's simply does not matter and it's disingenuous to say this only happened because the earthquake either damaged the main grid AC input/output to the reactors, or cause them to be shutdown, or both. It just doesn't matter, soon as that tsunami was on it's way at the height and volume of water Fukushima Daiichi was doomed.

 

@Curufinwe_winsWill likely be able to speak far more about it if actually possible or wishes to, but simply blaming this on both disaster events happening and so close together just doesn't wash with me, at all. Lame pun intended.

It's unfortunate the image doesn't quite do justice... The predicted maximum tsunami was 20 ft, so they not only built the ground level of the site to be 35 ft, but they also had it a rather significant distance away from the break water they put in place at that maximum 20 ft projection. Instead, a *****50 FT***** tsunami hits and the volume of water is just not handleable. For many years, I was under the personal (definitely not official) position that there was a decent chance things could have been okay if the scram procedure was not automatic. I'm honestly not sure anymore because there is still the issue that all six of the external grid power lines were destroyed by the earthquake. 

 

Running a power generator while disconnected from grid power is called islanding. French power plants do islanding tests on a regular basis, I don't know offhand if these GE MARK 1 BWR designs (quite old, but not exactly poorly built) were capable of islanding, or if the pumps available even had the capacity to remove the total volume of water being brought into the area (to keep the turbine buildings from flooding). It is really the tsunami and inability to respond to the ULOSSP event quickly and decisively (Japanese culture played a not insignificant role in indecisiveness here), that caused the actual meltdown, but I don't think it is particularly worthwhile to separate the events, as soon as one occurred the other was inevitable (given the epicenter and energy release).

 

I've always found it a bit disingenuous that people talk about Tepco 'ignoring the evidence of large tsunami's on a 1 per 1000 years basis' given the number and accuracy of reporting that actually suggests. It means perhaps there are records of 1 event with actual numeric reference and maybe as many as 3 or 4 with comparative unknown scale. 

 

The original site bluff was 35m above sea level, but dropping the height by 25m saved cost and *much more importantly* reduced earthquake risk  dramatically by permitting the plant to be built on solid rock. To some extent there is a bit of a 'you can't design for every possibility and have to accept that some events could hypothetically happen beyond your ability to mitigate them' feel to this particular disaster. With this said, I would specifically like to call out the Onagawa plant and situation as one worth looking into. These plants were built one decade later, and a single high ranking individual caused a choice that probably wasn't even justifiable at the time which meant their seawall was *just* tall enough to block most of the tsunami effects.

 

Quote

The Onagawa Nuclear Power Plant was the closest nuclear power plant to the epicenter of the 2011 Tōhoku earthquake,[14] less than half the distance of the stricken Fukushima I power plant.[15] The town of Onagawa to the northeast of the plant was largely destroyed by the tsunami[16] which followed the earthquake, but the plant's 14 meters (46 ft) high seawall was tall and robust enough to prevent the power plant from experiencing severe flooding. Yanosuke Hirai, who died in 1986, is cited as the only person on the entire power station construction project to push for the 14.8-meter breakwater. Although many of his colleagues regarded 12 meters as sufficient, Hirai's authority eventually prevailed, and Tōhoku Electric spent the extra money to build the 14.8m tsunami wall. Another of Hirai's proposals also helped ensure the safety of the plant during the tsunami: expecting the sea to draw back before a tsunami, he made sure the plant's water intake cooling system pipes were designed so it could still draw water for cooling the reactors.[17][better source needed]

All safety systems functioned as designed, the reactors automatically shut down without damage, and no reactor damage occurred.[18] A fire broke out in the turbine hall,[19][20][21] which is sited separately from the plant's reactor[22] in a building housing the electricity-generating turbine, but was soon extinguished.[23]

Following the tsunami, two to three hundred residents of the town who lost their homes to the tsunami took refuge in the Onagawa nuclear plant's gymnasium, as the reactor complex was the only safe area in the vicinity to evacuate to, with the reactor operators supplying food and blankets to the needy.

 

https://en.wikipedia.org/wiki/Onagawa_Nuclear_Power_Plant

 

 

EDIT: This is a good summary of the full proximate and direct causes.

 

https://www.world-nuclear-news.org/RS_Earthquake_not_a_factor_in_Fukushima_accident_0212111.html

 

Quote

Within an hour of the earthquake, however, almost the entire site was submerged to a depth of up to nine metres by a series of tsunami waves. Over about ten minutes these flooded six of the diesels and ruined the supporting equipment of another six. Only one diesel unit survived and this was used alternately to maintain essential systems at units 5 and 6 - using one of only three power distribution panels that had not been submerged. Some 36 other distribution panels throughout the emergency diesel generator system were made useless by water.

 

[leadeater]

40 minutes ago, Curufinwe_wins said:

but I don't think it is particularly worthwhile to separate the events, as soon as one occurred the other was inevitable (given the epicenter and energy release).

I don't particularly either, however I did so more so to prove a point that this whole situation was not caused simply because the earthquake caused SCRAM and had it otherwise been left running would have been able to provide it's own power for cooling. That's just not realistic and ignores all the water damage, way too much focus on just the generators alone and not enough stepping back and realizing the water level was near the height of the buildings and basically everything was fucked, to not put it lightly.

 

Fukushima Daini was also nearly equally as stricken, however it had 1 surviving main power feed so they were able to monitor reactor metrics. All the main cooling pumps were water damaged and the reactors were all on the verge of going critical just like Daiichi.

 

I personally find Daini to be the most interesting as it's the most similar situation to Daiichi.

 

Quote

The tsunami caused the plant's seawater pumps, used to cool reactors, to fail. Of the plant's four reactors, three were in danger of meltdown.

Just like Daiichi

 

Quote

One external high-voltage power line still functioned, allowing plant staff in the central control room to monitor data on internal reactor temperatures and water levels. 2,000 employees of the plant worked to stabilize the reactors. Some employees connected over 9 kilometers of cabling using 200-meter sections of cable, each weighing more than a ton from their Rad Waste Building to other locations onsite.

Unlike Daiichi

 

Quote

The steam powered reactor core isolation cooling system (RCIC) in all 4 units was activated and ran as needed to maintain water level. At the same time, operators utilized the safety relief valve systems to keep the reactor pressures from getting too high by dumping the heat to the suppression pools.[13] In unit 3, one seawater pump remained operational and the residual heat removal system (RHR) was started to cool the suppression pool and later brought the reactor to cold shutdown on March 12

Unlike Daiichi

 

Quote

In units 1, 2, and 4 heat removal was unavailable, so the suppression pools began heating up and on March 12, the water temperature in the pools of units 1, 2, and 4 reached 100 °C between 05:30 and 06:10 JST,[20][21][22] removing the ability to remove pressure from the reactor and drywell.[13]

Much like Daiichi

 

Daini was so close to suffer the same fate as Daiichi, like reallllly close. Daini being Mark 2 reactors and having 1 intact main supply along with later being able to get RCIC operational is what saved them. Had that 1 surviving main supply not been intact who knows what would have happened.

 

Question for you, do the Mark 1's have RCIC?

[leadeater]

Never mind found the answer

 

Quote

During a station blackout (where all off-site power is lost and the diesel generators fail) the RCIC system may be "black started" with no AC and manually activated. The RCIC system condenses its steam into the reactor suppression pool. The RCIC can make up this water loss, from either of two sources: a makeup water tank located outside containment, or the wetwell itself. RCIC is not designed to maintain reactor water level during a LOCA or other leak. Similar to HPCI, the RCIC turbine can be run in recirculation mode to remove steam from the reactor and help depressurize the reactor. [9]

 

Versioning note: RCIC and HPCF are integrated in the ABWRs, with HPCF representing the high-capacity mode of RCIC. Older BWRs such as Fukushima Unit 1 and Dresden as well as the new (E)SBWR do not have a RCIC system, and instead have an Isolation Condenser system.

No Daiichi did not have RCIC except in maybe reactor 6. The rest had IC and those ran dry.

[Curufinwe_wins]

36 minutes ago, leadeater said:

I don't particularly either, however I did so more so to prove a point that this whole situation was not caused simply because the earthquake caused SCRAM and had it otherwise been left running would have been able to provide it's own power for cooling. That's just not realistic and ignores all the water damage, way too much focus on just the generators alone and not enough stepping back and realizing the water level was near the height of the buildings and basically everything was fucked, to not put it lightly.

 

Fukushima Daini was also nearly equally as stricken, however it had 1 surviving main power feed so they were able to monitor reactor metrics. All the main cooling pumps were water damaged and the reactors were all on the verge of going critical just like Daiichi.

 

I personally find Daini to be the most interesting as it's the most similar situation to Daiichi.

 

Just like Daiichi

 

Unlike Daiichi

 

Unlike Daiichi

 

Much like Daiichi

 

Daini was so close to suffer the same safe as Daiichi, like reallllly close. Daini being Mark 2 reactors and having 1 intact main supply along with later being able to get RCIC operation is what saved them. Had that 1 surviving main supply not been intact who knows what would have happened.

 

Question for you, do the Mark 1's have RCIC?

Daini had a maximum tsunami height of only 9m, which is quite different than the 15m that has been estimated for Daiichi (despite the paltry 12km distance between them), so I do think that played a very large role as well in the difference.

 

The Mark 1 GE BWRs do not have RCIC, and instead had Isolation Condenser systems, but even that distinction is somewhat mute given all the seawater pumps were also destroyed between the earthquake and tsunami, so unless running them through the tsunami start could have kept them operational, there was no where for waste heat to go regardless. No connection to the ultimate heat sink (ocean).

 

https://en.wikipedia.org/wiki/Isolation_condensor

 

I don't know what the rated heat load of the IC systems were for the Daichi plants, but running out of condensate water was a serious issue in the days after and there was a lot of confusion as to what the best course of operation was there (or if it was acceptable to try to dump untreated seawater into the system).