Sayano-Shushenskaya Hydroelectric Station Disaster

[john_pifer]

Came across the Wiki article about this disaster while researching power station accidents:

Sayano-Shushenskaya Hydroelectric Station Disaster

Amateur video of the disaster taken a few moments after it started, from outside the plant:



Pretty crazy.

What is it with the Russians and power stations?

This station was built in the late 1970s. The technology was very well-understood by then, and you'd think that the people in charge of design, materials and construction techniques to prevent catastrophic failures like this one would have ensured it was done right. The way I look at it, I'd rather spend more any day on the front end of a project, than have to completely rebuild it because it self-destructed.

Of course, the other main factor was an improper repair that was made on the turbine.

What blows my mind is that everyone knew that turbine #2 was messed up, even from very soon after it was spooled up for the first time. It was vibrating well beyond limits in more than one regime, but nobody did anything about it. There was also corrosion and metal fatigue everywhere in the structural parts of the turbine unit and housing, etc. So, it wasn't maintained properly.

Sure, the cost would have been astronomical to stop plant operations to fix #2. But the cost of NOT fixing it turned out to be many orders of magnitude higher.

The resulting disaster was horrendous. 75 people killed, billions of dollars in damage, many people's livelihoods interrupted, environmental pollution, etc.

Chernobyl was a different type of power station and disaster, but both were preventable and caused by negligence and other human factors.

 

[SubieRubyRoo]

I see it every day- preventive and predictive maintenance are ignored and overlooked in chase of the almighty dollar. So far, the only organization that I have worked for that followed preventive and corrective maintenance to a “T” was the Navy. Every other business wrings every last nickel out of equipment regardless of the potential fallout; lives, equipment, or cost. Insurance doesn’t cover maintenance, that’s all I’m sayin’.

 

[maxdustington]

A lot of these mega projects were built to demonstrate soviet technical superiority, not to be well designed. It would be much easier to smile and nod than to protest and make enemies with people who had careers riding on projects like this.

 

[john_pifer]

Originally Posted By: SubieRubyRoo
I see it every day- preventive and predictive maintenance are ignored and overlooked in chase of the almighty dollar. So far, the only organization that I have worked for that followed preventive and corrective maintenance to a “T” was the Navy. Every other business wrings every last nickel out of equipment regardless of the potential fallout; lives, equipment, or cost. Insurance doesn’t cover maintenance, that’s all I’m sayin’.


Indeed - I'm in aircraft maintenance. I was never in the service, but I work with a lot of folks who were, and the military tends to adopt "best practices" when it comes to maintenance...again, from what I've heard. Some of y'all's experiences may be different. But I know a lot of the SOPs the military goes by are "written in blood". You'd think the Russians would have learned from Chernobyl. It seems we did learn from Three Mile Island, as we've not had another big accident/incident since.

Fukushima - now that one blows my mind, too. Major design flaws. A nuke plant in a major earthquake/tsunami zone, like that, should be built to withstand anything. They evidently thought it was. It wasn't.

 

[john_pifer]

Originally Posted By: maxdustington
A lot of these mega projects were built to demonstrate soviet technical superiority, not to be well designed. It would be much easier to smile and nod than to protest and make enemies with people who had careers riding on projects like this.


I know, but there were still multiple missed chances to recognize problems that existed and fix them, even well after Soviet times.

 

[CT8]

Originally Posted By: maxdustington
A lot of these mega projects were built to demonstrate soviet technical superiority, not to be well designed. It would be much easier to smile and nod than to protest and make enemies with people who had careers riding on projects like this.
The U.S. has has dam failures as well.There was a fear the Oroville Dam was goingto have trouble a few years ago. Great reporting of the project on youtube by link to youtube site.

 

[john_pifer]

Originally Posted By: CT8
Originally Posted By: maxdustington
A lot of these mega projects were built to demonstrate soviet technical superiority, not to be well designed. It would be much easier to smile and nod than to protest and make enemies with people who had careers riding on projects like this.
The U.S. has has dam failures as well.There was a fear the Oroville Dam was goingto have trouble a few years ago. Great reporting of the project on youtube by link to youtube site.


I think Oroville was a completely different situation. I invite you to read the Wiki entries for both disasters.

 

[john_pifer]

Documentary featuring some of the people who worked and lived there:


https://youtu.be/XJ6G0rxnzbw

 

[Ducked]

DP sorry. (See below)

 

[Ducked]

Originally Posted By: john_pifer

Fukushima - now that one blows my mind, too. Major design flaws. A nuke plant in a major earthquake/tsunami zone, like that, should be built to withstand anything. They evidently thought it was. It wasn't.


If THE JAPANESE can screw up a nuclear programme, ANYONE can, as others (not least the UK) have demonstrated.

Bottom line seems to be that this generic type of reactor, at least (Westinghouse PWR IIRC?) is inherently unsafe by design and people just can't be trusted to run them.

There was quite a lot of interest and discussion here because it wasn't that far upwind, (and there are a few of them on this small and crowded island.)

I was quite surprised by the inherently unsafe nuclear waste storage onsite, which had the potential to be at least as big a problem, but apparently its standard practice.

"Its quite difficult to get someone to see a problem if thier salary depends on them not seeing it."

 

[Y_K]

important factor most in The West miss: the almighty vodka

 

[maxdustington]

I think that nuke plants are the most technologically advanced infrastructure you can have. An advanced country like Japan has to have one, no matter how unsuited the land is. Overkill has made a few posts about the ones in Ontario, we have two and I am proud of them. Nuclear energy is the key to space travel!

 

[xxch4osxx]

Originally Posted By: maxdustington
I think that nuke plants are the most technologically advanced infrastructure you can have. An advanced country like Japan has to have one, no matter how unsuited the land is. Overkill has made a few posts about the ones in Ontario, we have two and I am proud of them. Nuclear energy is the key to space travel!
The CANDU reactors are one of the safest reactors in the world. I wish we would build more of them!

 

[OVERKILL]

Originally Posted By: Ducked
Originally Posted By: john_pifer

Fukushima - now that one blows my mind, too. Major design flaws. A nuke plant in a major earthquake/tsunami zone, like that, should be built to withstand anything. They evidently thought it was. It wasn't.


If THE JAPANESE can screw up a nuclear programme, ANYONE can, as others (not least the UK) have demonstrated.

Bottom line seems to be that this generic type of reactor, at least (Westinghouse PWR IIRC?) is inherently unsafe by design and people just can't be trusted to run them.

There was quite a lot of interest and discussion here because it wasn't that far upwind, (and there are a few of them on this small and crowded island.)

I was quite surprised by the inherently unsafe nuclear waste storage onsite, which had the potential to be at least as big a problem, but apparently its standard practice.

"Its quite difficult to get someone to see a problem if thier salary depends on them not seeing it."


The Japanese, or rather TEPCO in this case, screwed it up by not following the recommended changes to the site as per the Nuclear safety commission, some of which were indicated decades earlier. Some of these changes had been updates to the site design from General Electric for that quite aged BWR unit, others were overall safety changes. Some key items in this list include, but are not limited to:

- Relocation of the backup generators from in front of the reactor buildings, between them and the sea wall, to behind, on the rear of the site, and elevated, to protect them from flood-out
- Significantly increase the size of the sea wall, as the design was no longer considered adequate

These two changes alone would have mitigated the disaster; in fact the first one alone likely would have been sufficient to completely prevent it, albeit allowed significant structural damage to the facility to still occur.

TEPCO turned a deaf ear and the sea wall was overwhelmed, the backup generators flooded, which meant no cooling for the spent fuel pools, which boiled dry and the result was massive damage to the facility, rendering it permanently inoperable and had risked the situation being significantly more serious than it was.

There are many different reactor designs in use all over the world, all of them are significantly safer than the graphite-moderated units that were operating at Chernobyl. I'd argue the safest are the CANDU units here in Canada, but I might be a bit biased

 

[PimTac]

Originally Posted By: john_pifer
Originally Posted By: SubieRubyRoo
I see it every day- preventive and predictive maintenance are ignored and overlooked in chase of the almighty dollar. So far, the only organization that I have worked for that followed preventive and corrective maintenance to a “T” was the Navy. Every other business wrings every last nickel out of equipment regardless of the potential fallout; lives, equipment, or cost. Insurance doesn’t cover maintenance, that’s all I’m sayin’.


Indeed - I'm in aircraft maintenance. I was never in the service, but I work with a lot of folks who were, and the military tends to adopt "best practices" when it comes to maintenance...again, from what I've heard. Some of y'all's experiences may be different. But I know a lot of the SOPs the military goes by are "written in blood". You'd think the Russians would have learned from Chernobyl. It seems we did learn from Three Mile Island, as we've not had another big accident/incident since.

Fukushima - now that one blows my mind, too. Major design flaws. A nuke plant in a major earthquake/tsunami zone, like that, should be built to withstand anything. They evidently thought it was. It wasn't.





For perspective, we should remember that this was more than a large quake, it was catastrophic. I’ve been through a 7.2. This was a 9+. The resulting tsunami was also cataclysmic. Sometimes it just doesn’t matter how strong we build something, nature has a way of defeating it.

 

[Ducked]

Originally Posted By: maxdustington
I think that nuke plants are the most technologically advanced infrastructure you can have. An advanced country like Japan has to have one, no matter how unsuited the land is. Overkill has made a few posts about the ones in Ontario, we have two and I am proud of them. Nuclear energy is the key to space travel!


Spoken like a true Space Cadet.

(Except the Canadian reactors bit. By all accounts if you have to have these things, those are the ones to have.)

By contrast, the UK is commissioning a Chinese reactor. Now I don't fully subscribe to the Sino-slagging that is common on here, but.....

 

[Ducked]

Originally Posted By: OVERKILL
Originally Posted By: Ducked
Originally Posted By: john_pifer

Fukushima - now that one blows my mind, too. Major design flaws. A nuke plant in a major earthquake/tsunami zone, like that, should be built to withstand anything. They evidently thought it was. It wasn't.


If THE JAPANESE can screw up a nuclear programme, ANYONE can, as others (not least the UK) have demonstrated.

Bottom line seems to be that this generic type of reactor, at least (Westinghouse PWR IIRC?) is inherently unsafe by design and people just can't be trusted to run them.

There was quite a lot of interest and discussion here because it wasn't that far upwind, (and there are a few of them on this small and crowded island.)

I was quite surprised by the inherently unsafe nuclear waste storage onsite, which had the potential to be at least as big a problem, but apparently its standard practice.

"Its quite difficult to get someone to see a problem if thier salary depends on them not seeing it."


The Japanese, or rather TEPCO in this case, screwed it up by not following the recommended changes to the site as per the Nuclear safety commission, some of which were indicated decades earlier. Some of these changes had been updates to the site design from General Electric for that quite aged BWR unit, others were overall safety changes. Some key items in this list include, but are not limited to:

- Relocation of the backup generators from in front of the reactor buildings, between them and the sea wall, to behind, on the rear of the site, and elevated, to protect them from flood-out
- Significantly increase the size of the sea wall, as the design was no longer considered adequate

These two changes alone would have mitigated the disaster; in fact the first one alone likely would have been sufficient to completely prevent it, albeit allowed significant structural damage to the facility to still occur.

TEPCO turned a deaf ear and the sea wall was overwhelmed, the backup generators flooded, which meant no cooling for the spent fuel pools, which boiled dry and the result was massive damage to the facility, rendering it permanently inoperable and had risked the situation being significantly more serious than it was.

There are many different reactor designs in use all over the world, all of them are significantly safer than the graphite-moderated units that were operating at Chernobyl. I'd argue the safest are the CANDU units here in Canada, but I might be a bit biased

Implementing those precautions would probably have mitigated the disaster, but doesn't address the general issue.

I remember a quote from one of the pre-disaster TEPCO documents that a (containment failure or cooling failure, I THINK the former) was "unthinkable".

Anyone who uses that word in relation to something they are paid to think about (and which is actually easy to think about because its so bleeding obvious, but they didnt want to think about it) should have been fired PDQ.

This is a device that requires continuous active cooling not only while its running but for up to a week after its been shut down, or it blows up/melts down, releasing radiation. You don't have to be a nuclear physicist to see an inherent problem with that and it probably helps if you aren't.

At the time I initially assumed that the spare/spent fuel rods would be stored separated by quenching materials to ensure they couldn't go critical in the event of pond cooling loss, because I thought you'd have to be off your ******* head to do anything else.

Turned out they are stored in open ponds at quite high densities, with no quenching materials, for capacity reasons, and once the cooling is lost, all bets are off.

This is apparently standard practice.

 

[pandus13]

Originally Posted By: Y_K
important factor most in The West miss: the almighty vodka

Not really:
It is exactly like the allmighty complaints about building a vehicle in the West: The bean counters always win, not the engineers.

In this case, beside the bean counters you had the politrucs (political higher-ups and their minions, the political police) who usually wanted a project done by a certain date or even earlier (bonus at the 5-years party congress) no matter what.

 

[OVERKILL]

Originally Posted By: Ducked


At the time I initially assumed that the spare/spent fuel rods would be stored separated by quenching materials to ensure they couldn't go critical in the event of pond cooling loss, because I thought you'd have to be off your ******* head to do anything else.

Turned out they are stored in open ponds at quite high densities, with no quenching materials, for capacity reasons, and once the cooling is lost, all bets are off.

This is apparently standard practice.


Well, first, you can't lump spare and spent fuel together, one is used, still producing a significant amount of decay heat, the other is not. Traditional BWR/PWR reactors are fuelled all at once with the entire core being swapped out and still producing vast quantities of heat, so it isn't feasible to move that fuel a significant distance from the unit when one considers the handling requirements.

In the spent fuel pool, if the water is boiled off, there's no moderator, so nothing to maintain a chain reaction. Also, spent fuel, by virtue of being spent and having lower enrichment, shouldn't be able to sustain a reaction. There are other safety measures built into the racks:

Quote:
According to nuclear plant safety specialists, the chances of criticality in a spent fuel pool are very small, usually avoided by the dispersal of the fuel assemblies, inclusion of a neutron absorber in the storage racks and overall by the fact that the spent fuel has too low an enrichment level to self-sustain a fission reaction. They also state that if the water covering the spent fuel evaporates, there is no element to enable a chain reaction by moderating neutrons.


The primary risks with spent fuel are the exposure to radiation and cladding fire if the coolant were to dry up, releasing radiation into the air.

Now, with a CANDU, the fuel is never enriched, this requires heavy water to maintain any sort of reaction. The spent storage pools for a CANDU are entirely light water. Also, the fuel rods have to be in a specific orientation for criticality to occur and persist, any deviation from that and it stops. A CANDU is also fuelled on the fly, so you don't have the entire contents of the reactor coming out at once and being stored, rather, you instead have a bundle that has been moved around the reactor and finally reached end of life, moved by robot into the pool to join others that have been in there for various periods of time.

The storage time for a CANDU fuel bundle in wet storage is 7-10 years versus 10-20 years for an enriched Uranium reactor. Once the decay heat has been sufficiently reduced, the bundles are then moved into dry storage.

Now, it is possible for spent PWR/BWR fuel to be recycled. The EU does this through reprocessing them and China is now doing this using CANDU's, which can be fuelled directly with spent fuel, extracting an additional 40% more from the uranium. This latter process also has the side benefit of producing a less dangerous, lower heat producing final product to be stored or further reprocessed.

Bruce Power did up this little blurb after Fukushima happened, it's worth the read if you are interested in some of the other differences that set the CANDU's apart:
http://www.brucepower.com/the-difference-between-bruce-power-and-fukushima/

 

[Ducked]

Originally Posted By: OVERKILL
Originally Posted By: Ducked


At the time I initially assumed that the spare/spent fuel rods would be stored separated by quenching materials to ensure they couldn't go critical in the event of pond cooling loss, because I thought you'd have to be off your ******* head to do anything else.

Turned out they are stored in open ponds at quite high densities, with no quenching materials, for capacity reasons, and once the cooling is lost, all bets are off.

This is apparently standard practice.


Well, first, you can't lump spare and spent fuel together, one is used, still producing a significant amount of decay heat, the other is not. Traditional BWR/PWR reactors are fuelled all at once with the entire core being swapped out and still producing vast quantities of heat, so it isn't feasible to move that fuel a significant distance from the unit when one considers the handling requirements.

In the spent fuel pool, if the water is boiled off, there's no moderator, so nothing to maintain a chain reaction. Also, spent fuel, by virtue of being spent and having lower enrichment, shouldn't be able to sustain a reaction. There are other safety measures built into the racks:

Quote:
According to nuclear plant safety specialists, the chances of criticality in a spent fuel pool are very small, usually avoided by the dispersal of the fuel assemblies, inclusion of a neutron absorber in the storage racks and overall by the fact that the spent fuel has too low an enrichment level to self-sustain a fission reaction. They also state that if the water covering the spent fuel evaporates, there is no element to enable a chain reaction by moderating neutrons.


The primary risks with spent fuel are the exposure to radiation and cladding fire if the coolant were to dry up, releasing radiation into the air.

Now, with a CANDU, the fuel is never enriched, this requires heavy water to maintain any sort of reaction. The spent storage pools for a CANDU are entirely light water. Also, the fuel rods have to be in a specific orientation for criticality to occur and persist, any deviation from that and it stops. A CANDU is also fuelled on the fly, so you don't have the entire contents of the reactor coming out at once and being stored, rather, you instead have a bundle that has been moved around the reactor and finally reached end of life, moved by robot into the pool to join others that have been in there for various periods of time.

The storage time for a CANDU fuel bundle in wet storage is 7-10 years versus 10-20 years for an enriched Uranium reactor. Once the decay heat has been sufficiently reduced, the bundles are then moved into dry storage.

Now, it is possible for spent PWR/BWR fuel to be recycled. The EU does this through reprocessing them and China is now doing this using CANDU's, which can be fuelled directly with spent fuel, extracting an additional 40% more from the uranium. This latter process also has the side benefit of producing a less dangerous, lower heat producing final product to be stored or further reprocessed.

Bruce Power did up this little blurb after Fukushima happened, it's worth the read if you are interested in some of the other differences that set the CANDU's apart:
http://www.brucepower.com/the-difference-between-bruce-power-and-fukushima/


Your quote may be "best practice". I wonder if it is universal practice?

At the time I suspected not from comments here:-

https://www.physicsforums.com/threads/japan-earthquake-nuclear-plants.480200/page-8

Its a very long thread and I dunno how to search it, but at some point several days into the crisis, the experts (apparently) on there felt there was evidence of on-going criticality (I think from the species of decay product that were being released) and felt that this could be occurring either intermittently in a reactor core (fissile debris settling and blowing apart, then re-settling) or in the spent fuel ponds.

The phrase "open-air reactor" was used in the latter context. I hadn't heard that term before and would be quite glad if I never hear it again.

I'm fairly sure it was specifically stated that fuel rods were, at least sometimes, stored at quite high density without neutron absorber in the storage racks, for capacity reasons.

I remember this because I found it shocking, but I have no real way of knowing if its true.