How to lose 1200 MW

[MBfreak]

on an already strained national 400 kV power system. Trust the Ringhals personnel!
There are 6 remaining nuclear power plants in Sweden. Around 35% of total power input. Used to be 12, 52 %.
One plant 1,2 GW, was down for annual maintenance, around 4 weeks. During prestart checks the boneheads managed to melt down a steam reheater.
Ran it without water. Total meltdown. Will take at best 6 months to repair. It is a component with high radioactive content, all work must be done by robots.

Will add a considerable increase per kWh for all consumers.


SAPFU

Ola

 

[wyliesdiesels]

on an already strained national 400 kV power system. Trust the Ringhals personnel!
There are 6 remaining nuclear power plants in Sweden. Around 35% of total power input. Used to be 12, 52 %.
One plant 1,2 GW, was down for annual maintenance, around 4 weeks. During prestart checks the boneheads managed to melt down a steam reheater.
Ran it without water. Total meltdown. Will take at best 6 months to repair. It is a component with high radioactive content, all work must be done by robots.

Will add a considerable increase per kWh for all consumers.


SAPFU

Ola

im a nuclear plant and radiation nerd. which plant did this happen at? I cant find anything online

US reactors dont have steam reheaters... sounds like its a single loop system since the steam components are exposed to reactor coolant.

 

[larry4406]

Unit 4 appears to be a PWR and apparently the reactor pressure vessel was damaged.

Vattenfall extends outage of Sweden’s Ringhals 4 - Nuclear Engineering International

Swedish utility Vattenfall has delayed the restart of unit 4 at the Ringhals NPP by two months to 31 January 2023. "The unforeseen required repairs are taking more time than expected, before starting up the unit after the yearly maintenance," Vattenfall said in a regulatory filing.

www.neimagazine.com

Sweden's Ringhals 4 nuclear outage extends into winter months

Swedish utility Vattenfall said on Tuesday it had delayed the restart of the Ringhals 4 nuclear reactor by two months to Jan. 31, in a further setback to power supply in the Nordic and Baltic region.

www.reuters.com

Ringhals Nuclear Power Plant - Wikipedia

en.wikipedia.org

 

[wyliesdiesels]

Unit 4 appears to be a PWR and apparently the reactor pressure vessel was damaged.

Vattenfall extends outage of Sweden’s Ringhals 4 - Nuclear Engineering International

Swedish utility Vattenfall has delayed the restart of unit 4 at the Ringhals NPP by two months to 31 January 2023. "The unforeseen required repairs are taking more time than expected, before starting up the unit after the yearly maintenance," Vattenfall said in a regulatory filing.

www.neimagazine.com

Sweden's Ringhals 4 nuclear outage extends into winter months

Swedish utility Vattenfall said on Tuesday it had delayed the restart of the Ringhals 4 nuclear reactor by two months to Jan. 31, in a further setback to power supply in the Nordic and Baltic region.

www.reuters.com

Ringhals Nuclear Power Plant - Wikipedia

en.wikipedia.org

Interesting.

MBfreak said a steam reheater was damaged. Maybe he was referring to the RPV? Odd name for an RPV as a PWR doesnt have steam in the first loop. Coolant runs through a heat exchanger and steam is generated in the second loop.

But I wonder how it melted down. Unless they were replacing the entire core of fuel, they wouldve needed to keep cooling water flowing through the core for the entire duration of the maintenance cycle due to decay heat....

Gonna do some digging

 

[larry4406]

Interesting.

MBfreak said a steam reheater was damaged. Maybe he was referring to the RPV? Odd name for an RPV as a PWR doesnt have steam in the first loop. Coolant runs through a heat exchanger and steam is generated in the second loop.

But I wonder how it melted down. Unless they were replacing the entire core of fuel, they wouldve needed to keep cooling water flowing through the core for the entire duration of the maintenance cycle due to decay heat....

Gonna do some digging

My thoughts as well. I was initially thinking the steam generator was overheated due to lack of water on the secondary side.

Bad jujo if the reactor pressure vessel is damaged. Talk about letting the genie out of the bottle.

 

[MBfreak]

Ringhals 4, Sweden. PWR, started 1985. The damaged part is a large tank ( diameter 3 m , height 12 m) in the secondary circuit that keeps the pressure within a specified range. Too low , large electric heaters goes on, too hot cold water is injected. And the boneheads started the large electric heaters with no water in the tank, during system check up after a small maintenance operation.

Ola

 

[MBfreak]

The reactor pressure vessel is undamaged and far away from the calamity!
The primary circuit is not involved.

Ola

 

[larry4406]

Ringhals 4, Sweden. PWR, started 1985. The damaged part is a large tank ( diameter 3 m , height 12 m) in the secondary circuit that keeps the pressure within a specified range. Too low , large electric heaters goes on, too hot cold water is injected. And the boneheads started the large electric heaters with no water in the tank, during system check up after a small maintenance operation.

Ola

Man - that is like a novice plumber or DIY guy turning on an electric tanked water heater without filling it and frying the elements in an instant.

 

[Jim greengo]

Man - that is like a novice plumber or DIY guy turning on an electric tanked water heater without filling it and frying the elements in an instant.

A couple heating elements in a water heater would be a little easier to change out. Hahaha

 

[RPH]

This is one reason control engineers make the big dollars. They are supposed to cover any possibility of failure. Not having a low water cut off in the circuit is unbelievable. With the nature of the industry one wonders where were the other safeties to prevent this from happening? Been involved with controls for over fifty years, you are taught to think like the machine does for every function. Then you figure out what can go wrong on each step. Design, materials, and code have to cover all bases.

 

[welder4956]

You nukes may know the "reheater" as the moisture separator reheater or MSR. Looks a lot like a feedwater heater. It is normally located in the turbine building near the condenser and there should be two of them.

 

[nadogail]

Shades of Three Mile Island, Chernobyl, and the US Army Reactor. The greatest problem with Nuclear Power Plants seems to be the Human Element.

 

[wyliesdiesels]

Shades of Three Mile Island, Chernobyl, and the US Army Reactor. The greatest problem with Nuclear Power Plants seems to be the Human Element.

theres been many more meltdowns than just those....

 

[wyliesdiesels]

The reactor pressure vessel is undamaged and far away from the calamity!
The primary circuit is not involved.

Ola

ummm you apparently didnt read the 2 links that larry provided above

The damage to the reactor's pressure vessel, a radioactive component, means that Ringhals must now build a full-size mock-up of the 12-metre (39 feet) tall structure for training before repairs can take place."

The 130MWe pressurised water reactor at Ringhals 4 was stopped for annual routine maintenance in August, but was not able to restart after the reactor pressure vessel (RPV) was damaged during tests. Vattenfall had initially expected the repairs to be completed by November

A full-scale model of the nearly 13-metre high-RPV is being built to test the tools and rehearse the operation. “The pressure vessel is radioactive, all work is carefully prepared, and practicing in a test environment helps us work safely and efficiently when we are ready to carry out the actual repair work,” Linde said in the press release.

no where in either article was a steam reheater mentioned.... The RPV was mentioned though

 

[wyliesdiesels]

You nukes may know the "reheater" as the moisture separator reheater or MSR. Looks a lot like a feedwater heater. It is normally located in the turbine building near the condenser and there should be two of them.

that would be on the secondary loop so not radioactive either

Dont think MBfreak is reading the same articles were reading here

 

[welder4956]

The "reheater" is on the secondary side as mentioned. It is located in the steam piping exiting the high pressure section of the steam turbine and it's function is to remove moisture and add heat to the steam before it enters the intermediate pressure or low pressure section of the steam turbine. There should be no radioactivity involved in this pressure vessel. One of the articles is misleading in calling it the "reactor's pressure vessel", which is not the same as the "reactor" or "reactor pressure vessel". It is simply one of many pressure vessels used in the steam cycle of most all steam powered power plants. Too much misleading info is put out by media to hype the possibility of nuclear disaster where there is no chance of it even coming close.

 

[mike93lx]

Ola, do you work there?

 

[wyliesdiesels]

The "reheater" is on the secondary side as mentioned. It is located in the steam piping exiting the high pressure section of the steam turbine and it's function is to remove moisture and add heat to the steam before it enters the intermediate pressure or low pressure section of the steam turbine. There should be no radioactivity involved in this pressure vessel. One of the articles is misleading in calling it the "reactor's pressure vessel", which is not the same as the "reactor" or "reactor pressure vessel". It is simply one of many pressure vessels used in the steam cycle of most all steam powered power plants. Too much misleading info is put out by media to hype the possibility of nuclear disaster where there is no chance of it even coming close.

yet it was the CEO of the plant owner who was quoted as saying the pressure vessel is radioactive so it wasnt the media putting out misleading info.

furthermore, one of the sources isnt some random media outlet, its a nuclear engineering magazine. I doubt they have the mentality to put out misleading info to hype the possibility of a nuclear disaster. Not to mention doing so is totally counter-productive to their existence....

your logic is flawed here.

 

[welder4956]

yet it was the CEO of the plant owner who was quoted as saying the pressure vessel is radioactive so it wasnt the media putting out misleading info.

furthermore, one of the sources isnt some random media outlet, its a nuclear engineering magazine. I doubt they have the mentality to put out misleading info to hype the possibility of a nuclear disaster.
your logic is flawed here.

Not flawed, just didn't notice the comment by the plant owner. If the reheater is radioactive, it means leakage has occurred previously in the steam generator tubes allowing some carryover into the steam leaving the steam generator and going to the high pressure section of the turbine. Not a big deal, as all BWRs and other PWRs with leaking steam generator tubes operate with contamination in the secondary side.

Edit: Contamination in the secondary side does slow the repair work down significantly though due to the need to use anti-contamination clothing and controls to prevent the spread of contamination.

 

[wyliesdiesels]

Not flawed, just didn't notice the comment by the plant owner. If the reheater is radioactive, it means leakage has occurred previously in the steam generator tubes allowing some carryover into the steam leaving the steam generator and going to the high pressure section of the turbine. Not a big deal, as all BWRs and other PWRs with leaking steam generator tubes operate with contamination in the secondary side.

Edit: Contamination in the secondary side does slow the repair work down significantly though due to the need to use anti-contamination clothing and controls to prevent the spread of contamination.

ok i found another article which actually attributed their article to reuters which stated it was the pressure vessel. this keeps the coolant under pressure to prevent it from boiling so it is on the primary loop thus making sense that its radioactive...

Restart of Sweden’s Ringhals 4 nuclear reactor delayed to end of November

The restart of Sweden’s Ringhals 4 nuclear reactor will be delayed by three months after a key component was damaged following an annual maintenance and

english.alarabiya.net

 

[welder4956]

ok i found another article which actually attributed their article to reuters which stated it was the pressure vessel. this keeps the coolant under pressure to prevent it from boiling so it is on the primary loop thus making sense that its radioactive...

Restart of Sweden’s Ringhals 4 nuclear reactor delayed to end of November

The restart of Sweden’s Ringhals 4 nuclear reactor will be delayed by three months after a key component was damaged following an annual maintenance and

english.alarabiya.net

I agree. The initial post of a problem with the "reheater" was confusing and perhaps a translation issue. The more I read, it sounds like the problem was that the electric heaters inside the pressurizer vessel burned out. The pressurizer is part of the primary loop and would contain radioactivity. No indication that the vessel failed, just that the heaters burned out.

https://group-vattenfall-com.transl...tr_sl=sv&_x_tr_tl=en&_x_tr_hl=en&_x_tr_pto=sc

 

[MBfreak]

I was involved in the system design of all control systems at R4. One af 50 in a group.
And since I am being misrepresented by some nuclear specialists here, please read welder 4956 posts, he has it right, also.

Even the underwear worn by maintenance personnel is classified as nuclear low level waste and must be handled as such.
Not to mention the pressurizer vessel and its internal parts.

A replica reheater is now being built with the sole purpose of establishing methods, plans and robotic tools that will be used to remove melted heaters, sanitize the vessel and installing new heater elements. Once proven and approved , the real work will begin on the plant reheater.
And a recent review indicates that operators during the trial did not follow explicit and extensive written instructions during the "work"
Strangely enough, this is the third time that happens at Ringhals.



Ola

 

[MBfreak]

I have now been given access to an internal doc describing the calamity.
Reviewed an approved nuclear safety authority
In short
The very detailed work procedure was not followed and the principle " 8 eyes and 4 brains "for each step was totally disregarded.

 

[Old Man Roger]

I know very very little about nuclear power plants, but isn’t the term you used “Melt Down” usually used when the actual fuel rods are not being cooled?

 

[jeepxj]

Ringhals 4, Sweden. PWR, started 1985. The damaged part is a large tank ( diameter 3 m , height 12 m) in the secondary circuit that keeps the pressure within a specified range. Too low , large electric heaters goes on, too hot cold water is injected. And the boneheads started the large electric heaters with no water in the tank, during system check up after a small maintenance operation.

Ola

no high temp lockout on the grid heaters?

 

[jeepxj]

I have now been given access to an internal doc describing the calamity.
Reviewed an approved nuclear safety authority
In short
The very detailed work procedure was not followed and the principle " 8 eyes and 4 brains "for each step was totally disregarded.

mmm human factor. always a treat.

 

[MBfreak]

jeepxj
detailed design qs not possible to answer.
Ola

 

[wyliesdiesels]

I know very very little about nuclear power plants, but isn’t the term you used “Melt Down” usually used when the actual fuel rods are not being cooled?

yes

 

[welder4956]

I know very very little about nuclear power plants, but isn’t the term you used “Melt Down” usually used when the actual fuel rods are not being cooled?

Yes, but lots of other things can melt down too. The first thing most people think of when they hear the words "nuclear" and "melt down" in the same sentence are a reactor melt down from loss of cooling. However, in this case it was electric heaters in a pressure vessel that was not the reactor.

 

[Old Man Roger]

Yes, but lots of other things can melt down too. The first thing most people think of when they hear the words "nuclear" and "melt down" in the same sentence are a reactor melt down from loss of cooling. However, in this case it was electric heaters in a pressure vessel that was not the reactor.

Ya, still not words I want to hear..lol

 

[kaffine]

I have now been given access to an internal doc describing the calamity.
Reviewed an approved nuclear safety authority
In short
The very detailed work procedure was not followed and the principle " 8 eyes and 4 brains "for each step was totally disregarded.

There is a reason I don't work in the nuclear industry anymore. I can't follow instructions that detailed.

In another industry I tried writing detailed instructions and found that most skipped 2 out of 3 steps.