German public now favors extending life of Nuclear power plants

[gathermewool]

Doesn‘t the proximity to fault lines for Japan and California play a role in deciding the public and economic feasibility of nuclear power? Germany is not near a fault line and is sheltered against things like tsunamis and doesn’t have nearly the same risk of earthquakes. It would appear that the only real lesson learned from Fukushima that would require evaluation and funding for mitigation of potential natural disaster effects is related to the recent severe floods wrt backup power generation for decay heat removal. Like, don’t put your dang backup gennies low and rely on a sea wall to protect them, for instance.

What sucks is that many places in the world are at much lower risk for natural disasters than Fukushima, but the perceived risk by the public is hard to get past. It doesn’t matter if a study is published that shows close to zero ground movement near your reactor, people who can’t comprehend these things will still be frightened or susceptible to negative propaganda and then fight against it and their own best interests. I would bet money that some would worry about radiation and contamination that will not ever harm them (ie, background levels of radiation at the perimeter of a plant), but see nuclear power as more of a threat than, say, a coal plant.

Case in point, my brother text me the other day that he had a dream that I became radioactive and that I came to see him and it was contagious. My response: “Brother, are you sitting down? I have something to tell you. Actually, I should probably tel you in person.“

 

[gathermewool]

This of course came from the decision to boycott Russian natural gas. It's not that everyone suddenly loves nuclear.

Exactly, but that doesn’t mean their decision to cut nuclear out of their portfolio was wise. Everything poses a risk, but nuclear power has a much higher perceived risk associated with it than is actually warranted in most cases. The problem is that existing nuclear plants are possibly seen as a necessary evil or may be even an “out of site, out of mind” kind of thing with as little money as possible available to keep them running, whereas newer plants that are likely a lot safer have to go through so much red tape that they‘re seen as a bad investment, so far as I can tell.

It doesn’t help when you have some examples of gross negligence, such as in Chernobyl and lack of foresight and appropriate risk mitigation, such as with Fukoshima, which scare people.

 

[BMWTurboDzl]

Doesn‘t the proximity to fault lines for Japan and California play a role in deciding the public and economic feasibility of nuclear power? Germany is not near a fault line and is sheltered against things like tsunamis and doesn’t have nearly the same risk of earthquakes. It would appear that the only real lesson learned from Fukushima that would require evaluation and funding for mitigation of potential natural disaster effects is related to the recent severe floods wrt backup power generation for decay heat removal. Like, don’t put your dang backup gennies low and rely on a sea wall to protect them, for instance.

What sucks is that many places in the world are at much lower risk for natural disasters than Fukushima, but the perceived risk by the public is hard to get past. It doesn’t matter if a study is published that shows close to zero ground movement near your reactor, people who can’t comprehend these things will still be frightened or susceptible to negative propaganda and then fight against it and their own best interests. I would bet money that some would worry about radiation and contamination that will not ever harm them (ie, background levels of radiation at the perimeter of a plant), but see nuclear power as more of a threat than, say, a coal plant.

Case in point, my brother text me the other day that he had a dream that I became radioactive and that I came to see him and it was contagious. My response: “Brother, are you sitting down? I have something to tell you. Actually, I should probably tel you in person.“

IMO the fear is that plant operators capture regulators and end up avoiding having to make prudent investments regarding safety.

 

[OVERKILL]

Doesn‘t the proximity to fault lines for Japan and California play a role in deciding the public and economic feasibility of nuclear power?

It has certainly been a factor, and will be one going forward, as it affects plant placement and design (seismic tolerance/integrity). Diablo Canyon is well sited apparently, as was SONGS. Cali's issues are primarily political, like in Germany, where folks like Lovins and Jacobson are seen as visionaries and leaders, not the pied pipers or false prophets that they are. Japan is rolling back into nuclear despite Fukushima, taking it as a learning experience in terms of their regulatory environment, but they don't have the same green party lunacy that other places do.

 

[OVERKILL]

IMO the fear is that plant operators capture regulators and end up avoiding having to make prudent investments regarding safety.

And that's exactly what happened in Japan, because their regulator was a body where the operators were on the board, so self interest was clearly a problem. The grandfathering legislation (don't need to make what would otherwise be necessary updates due to the age of the facility) is what doomed Fukushima Daiichi. GE had told them the generators should be moved to behind the plant. Not done. Newer plants were required to have higher sea walls, also not done.

In Canada, the nuclear regulating body is part of the Federal government. It's wholly independent and none of its staff work in any capacity with the organizations they are regulating. This ensures objectivity and eliminates any potential for industry capture. This should be standard.

 

[gathermewool]

It has certainly been a factor, and will be one going forward, as it affects plant placement and design (seismic tolerance/integrity). Diablo Canyon is well sited apparently, as was SONGS. Cali's issues are primarily political, like in Germany, where folks like Lovins and Jacobson are seen as visionaries and leaders, not the pied pipers or false prophets that they are. Japan is rolling back into nuclear despite Fukushima, taking it as a learning experience in terms of their regulatory environment, but they don't have the same green party lunacy that other places do.

Correct me if I’m wrong, but two things, at least, heavily mitigate a future issue like Fukushima:

1. Backup power for DHR making actual sense
2. Control H2 burn any potential H2 buildup before it literally blows the roof off.

Would Fukushima have even happened if these two things were logical, eg, the EDGs weren’t flooded out and the backup mode of DHR lost?

Future Rx designs do/should incorporate passive emergency DHR, so that a loss of heat sink (eg, the River) via SW-to-FW heat exchangers aren‘t required to prevent a melt down with long power histories and high DHR. I actually haven’t kept up with the newer Rx designs, so maybe this is a dumb, out-of-touch statement.

 

[OVERKILL]

Correct me if I’m wrong, but two things, at least, heavily mitigate a future issue like Fukushima:

1. Backup power for DHR making actual sense
2. Control H2 burn any potential H2 buildup before it literally blows the roof off.

Would Fukushima have even happened if these two things were logical, eg, the EDGs weren’t flooded out and the backup mode of DHR lost?

Future Rx designs do/should incorporate passive emergency DHR, so that a loss of heat sink (eg, the River) via SW-to-FW heat exchangers aren‘t required to prevent a melt down with long power histories and high DHR. I actually haven’t kept up with the newer Rx designs, so maybe this is a dumb, out-of-touch statement.

If either of the site upgrades had been made:
1. Relocate the backup generators to behind the plant
2. Upgrade the sea wall to be regulation height

The disaster would have been avoided completely. The wave took out the generators and fuel tanks. Had the wave been blocked, this wouldn't have happened. Had the generators not been in that location, that wouldn't have happened.

And you are quite right, hydrogen build-up was an issue (which is why they vented it) and there was significant concern about keeping the spent fuel pool water levels up because they had no operating pumps, because they had no power, which brings us back to 1 and 2.

Current designs (AP1000, EPR) are both capable of passive cooling. But, so are some existing designs like the CANDU. There's a whole story on how the CIA influenced Japanese reactor design selection and the fact that the event wouldn't have happened with CANDU units, but really, the event wouldn't have happened if the regulator wasn't boarded by the industry it was regulating and the upgrades had been performed as the knowledge of potential risks to plant safety evolved. There's nothing wrong with operating old plants as long as they kept reasonably up-to-date for emergency preparedness. The problem is that Fukushima Daiichi wasn't.

 

[gathermewool]

If either of the site upgrades had been made:
1. Relocate the backup generators to behind the plant
2. Upgrade the sea wall to be regulation height

The disaster would have been avoided completely. The wave took out the generators and fuel tanks. Had the wave been blocked, this wouldn't have happened. Had the generators not been in that location, that wouldn't have happened.

And you are quite right, hydrogen build-up was an issue (which is why they vented it) and there was significant concern about keeping the spent fuel pool water levels up because they had no operating pumps, because they had no power, which brings us back to 1 and 2.

Current designs (AP1000, EPR) are both capable of passive cooling. But, so are some existing designs like the CANDU. There's a whole story on how the CIA influenced Japanese reactor design selection and the fact that the event wouldn't have happened with CANDU units, but really, the event wouldn't have happened if the regulator wasn't boarded by the industry it was regulating and the upgrades had been performed as the knowledge of potential risks to plant safety evolved. There's nothing wrong with operating old plants as long as they kept reasonably up-to-date for emergency preparedness. The problem is that Fukushima Daiichi wasn't.

Are current designs able to indefinitely passively cool the secondary loop? I mean, you can NC the primary and bleed steam, but if you can’t get that secondary water back to the SG, then you’ll still eventually lose the heat sink.

 

[OVERKILL]

Are current designs able to indefinitely passively cool the secondary loop? I mean, you can NC the primary and bleed steam, but if you can’t get that secondary water back to the SG, then you’ll still eventually lose the heat sink.

CANDU's are able to passively cool for about 2 weeks by using convection with the SG's as heatsinks before makeup water becomes an issue (you'd need to have a pump working or some other method for adding makeup water, even if it was a bucket line at that point). I'd have to lookup how long passive cooling can work for the AP1000 and EPR, as I don't know off-hand.

Edit:
AP1000:
https://www.westinghousenuclear.com/energy-systems/ap1000-pwr/safety/passive-safety-systems

EPR:
https://www.nrc.gov/docs/ML0916/ML091671491.pdf

 

[gathermewool]

CANDU's are able to passively cool for about 2 weeks by using convection with the SG's as heatsinks before makeup water becomes an issue (you'd need to have a pump working or some other method for adding makeup water, even if it was a bucket line at that point). I'd have to lookup how long passive cooling can work for the AP1000 and EPR, as I don't know off-hand.

Edit:
AP1000:
https://www.westinghousenuclear.com/energy-systems/ap1000-pwr/safety/passive-safety-systems

EPR:
https://www.nrc.gov/docs/ML0916/ML091671491.pdf

How is makeup water added with no power to feed pumps? What does “bucket line” mean? Is that a means of depressurized gravity feed?

 

[OVERKILL]

How is makeup water added with no power to feed pumps? What does “bucket line” mean? Is that a means of depressurized gravity feed?

The top of the CANDU units is a giant tank, water is introduced into the system from this tank using gravity. A bucket line is literally folks with buckets, you'd just replenish this tank to make up for evaporation.

Edit:
Here's a CANDU 6 schematic, note the dousing tank in the top of the unit:

And note the location of the core relative to the SG's. This allows for convective cooling. The issue of course is the spent fuel pool, where evaporation is going to happen, so you will eventually need make-up water.

 

[gathermewool]

The top of the CANDU units is a giant tank, water is introduced using gravity. A bucket line is literally folks with buckets, you'd just replenish this tank to make up for evaporation.

OK, so the secondary is depressurized to ambient and they just bleed saturated steam at head pressure? Does that damage the secondary side or produce chemistry concerns?

 

[OVERKILL]

OK, so the secondary is depressurized to ambient and they just bleed saturated steam at head pressure? Does that damage the secondary side or produce chemistry concerns?

Yup, exactly, and the SG's become big 'ol heat sinks. I can't see any risk of damage unless you were introducing unfiltered water perhaps, but the contents of the tank is the same stuff that's already in the system, so the risk of damage/contamination would be from beyond the 2-week period.

 

[gathermewool]

Yup, exactly, and the SG's become big 'ol heat sinks. I can't see any risk of damage unless you were introducing unfiltered water perhaps, but the contents of the tank is the same stuff that's already in the system.

So this uses normal condensate from the steam bleeding, and this can be returned to the tank to gravity feed as makeup water? How is chemistry control maintained and the water de-aerated? I understand that this is a temporary concern for emergencies, but when power and normal cooling is eventually restored and the plant is expected to be restored to normal service, would this not be a concern Re: primary to secondary leaks?

 

[OVERKILL]

So this uses normal condensate from the steam bleeding, and this can be returned to the tank to gravity feed as makeup water? How is chemistry control maintained and the water de-aerated? I understand that this is a temporary concern for emergencies, but when power and normal cooling is eventually restored and the plant is expected to be restored to normal service, would this not be a concern Re: primary to secondary leaks?

Primary and secondary don't overlap, as the secondary circuit is light water and the primary circuit is heavy water. I'm honestly not sure on the chemistry question as we've never had to actually use this in application, so I don't have anybody I can ask about the implications beyond perhaps theoretical. This is a pressure tube, not pressure vessel design if that helps you envisage the layout?

- Primary circuit is heavy water, that flows through pressure tubes, which are located in a gigantic vat of heavy water (calandria)
- Secondary circuit is the pressurized steam circuit that is heated by the primary circuit through the steam generators
- Tertiary circuit is the heat removal circuit that takes excess heat out of the secondary circuit using lake water via the condensers (or ocean, in ocean facing plants)

In the scenario we are discussing, there is natural circulation (convection) in both the primary and secondary circuits, but makeup water is only needed in the secondary circuit where you've flooded the boilers and are using them and the condensers as heat sinks and flow is via convection. Tertiary circuit clearly isn't active, since you have no power. Makeup water from the same tank is used for the spent fuel pool as well.

This diagram shows the heat transport system, which might help if you envisage water from the tank on top being used for make-up:

 

[gathermewool]

Primary and secondary don't overlap, as the secondary circuit is light water and the primary circuit is heavy water. I'm honestly not sure on the chemistry question as we've never had to actually use this in application, so I don't have anybody I can ask about the implications beyond perhaps theoretical. This is a pressure tube, not pressure vessel design if that helps you envisage the layout.

I get that the primary and secondary systems are independent systems. Both have their own chemistry requirements, though. Both need proper pH and [insert other chemistry here], including O2, as well as particulate and sludge control for the secondary. Without feed pumps for an extended period the pH and [insert other chemistry here] can’t be maintained and, in the becket brigade method you mentioned, O2 is a concern, as well as CO2 effects on pH and other introduction of contaminants, including low level Chlorides. There is also limited ability to perform blowdowns.

This is obviously not the concern during an emergency, but a concern for plant restoration. If chemistry is compromised, there are also concerns regarding primary CRUD production and corrosion.

Just something to think about when it comes to restoration following a once-in-a-lifetime casualty. It’s not just as simple as “keep the core covered”. Or maybe it is. I don’t know for sure.

One additional question: for the gravity feed of the secondary to work the primary T/P would also need to be lowered, right? How is the makeup water for that accounted for?

 

[OVERKILL]

I get that the primary and secondary systems are independent systems. Both have their own chemistry requirements, though. Both need proper pH and [insert other chemistry here], including O2, as well as particulate and sludge control for the secondary. Without feed pumps for an extended period the pH and [insert other chemistry here] can’t be maintained and, in the becket brigade method you mentioned, O2 is a concern, as well as CO2 effects on pH and other introduction of contaminants, including low level Chlorides. There is also limited ability to perform blowdowns.

This is obviously not the concern during an emergency, but a concern for plant restoration. If chemistry is compromised, there are also concerns regarding primary CRUD production and corrosion.

Just something to think about when it comes to restoration following a once-in-a-lifetime casualty. It’s not just as simple as “keep the core covered”. Or maybe it is. I don’t know for sure.

One additional question: for the gravity feed of the secondary to work the primary T/P would also need to be lowered, right? How is the makeup water for that accounted for?

I think during the emergency, it pretty much would be that simple. You are quite right that there may be issues during restoration however, not only from not being able to maintain (or monitor) the chemistry in these systems but also from the introduction of contaminants if you were to require makeup water from the lake (bucket brigade). But that would require an outage that spans beyond the 2-week window provided by the tank.

Another neat CANDU feature is that they can island, so you aren't forced to shutdown the unit and depend on auxiliary power to keep things going. The unit can drop to idle and run itself and all its services.

I take it you work in powergen, just not nuclear?

 

[andrew_j]

It’s good when policy shifts and adapts. Diversity in energy is place to be from green, fossil, nukes etc.

 

[gathermewool]

I think during the emergency, it pretty much would be that simple. You are quite right that there may be issues during restoration however, not only from not being able to maintain (or monitor) the chemistry in these systems but also from the introduction of contaminants if you were to require makeup water from the lake.

Another neat CANDU feature is that they can island, so you aren't forced to shutdown the unit and depend on auxiliary power to keep things going. The unit can drop to idle and run itself and all its services.

I take it you work in powergen, just not nuclear?

Interesting. I really need to read up on this.

Re: islanding. That wouldn’t really be an option for a Rx that was SCRAMMED or SD and couldn’t immediately be brought back online to self-sustaining (idle), right? Do these Rx’s use decay heat to produce enough power to run pumps for a period of time?

On second thought, I guess chemistry samples could be drawn, so they would at least know whether contaminants like chlorides were a concern. If the emergency affected power to run pumps, but not the ability to feed and bleed, potential corrosion could be mitigated.

If lake water needs to be injected, then I would guess that things are really bad and recovery isn’t much of a consideration short-term.

 

[gathermewool]

It’s good when policy shifts and adapts. Diversity in energy is place to be from green, fossil, nukes etc.

The problem is that policy isn’t constrained to what is most prudent. Feelings, emotions and uneducated opinions and pressures sometimes prevail.