Nuclear power in US - safety against unforeseen situations.

[Dmytry]

A couple questions.
1: Does US have anything similar to KHG? US robots on site in Fukushima - one with digital radiation monitor, other looking at first through camera - is that what US would use at US reactor accident? Is there a shortage / unavailability of such equipment for US-built reactors aboard?
2: Can the generators and substitute electrical equipment be quickly delivered on site by heavy transport helicopter in the event of failure of electrical systems like Fukushima (and successfully connected) ? Ditto for fuel and water. Ditto for pumps. So that all the critical safety equipment can be replaced with portable substitute. I know that German equipment is standardized and common industrial generators working at common voltages can be used to power cooling pumps. From Fukushima I know that they could not do this.
3: Why nuclear power plants don't have helicopter pads on the roofs just in case?

 

[Drakkith]

3: Why nuclear power plants don't have helicopter pads on the roofs just in case?

In case of what? Wouldn't it be better to have it in an open field nearby? Otherwise you run into the problem of unloading heavy equipment from a rooftop and other things.

 

[Drakkith]

Oh, also I do know that current reactor designs are much different than the ones in Japan. I believe that there are many more passive safety features that should prevent much of what happened in japan. (In your words this would be "Generic" safety features.)

 

[Dmytry]

Do you have any answers? I am asking specific questions. So far I take your answer as "No and I don't think anything like that is necessary".
For helicopter pad - auxiliary in the event that there's mess on the ground.

 

[Joseph Chikva]

2: Can the generators and substitute electrical equipment be quickly delivered on site by heavy transport helicopter in the event of failure of electrical systems like Fukushima (and successfully connected) ? Ditto for fuel and water. Ditto for pumps. So that all the critical safety equipment can be replaced with portable substitute. I know that German equipment is standardized and common industrial generators working at common voltages can be used to power cooling pumps. From Fukushima I know that they could not do this.

Weight (mass) of that equipment? How it corresponds to load-carrying capacity of the heavy-lift helicopters available in the market (Mi-26, Chinook, Stallion)? On Fukushima we see that those equipments have been installed after a few days after accident. Is this option so critical for total safety level of power plant?

3: Why nuclear power plants don't have helicopter pads on the roofs just in case?

The simple answer to this question - builders build according to the approved design. And in that design the helicopter pad on a roof does not provided.

 

[Dmytry]

Weight (mass) of that equipment? How it corresponds to load-carrying capacity of the heavy-lift helicopters available in the market (Mi-26, Chinook, Stallion)?

I am asking the question, whenever there is such capability? Until i get 'no' i am not asking why there isn't.

On Fukushima we see that those equipments have been installed after a few days after accident.

Ohh right and then they couldn't power even the spent fuel pool pumps. Meaning the did not have this capability.

Is this option so critical for total safety level of power plant?

I'm curious if engineers think that it is so critical. I'll myself think whenever it looks more like they're planning for 1 in 100 or 1 in 10 000 lifetime risk of failure.

The simple answer to this question - builders build according to the approved design. And in that design the helicopter pad on a roof does not provided.

switchgear in basement however is provided.

 

[Joseph Chikva]

I think (sure) that most of that equipment is heavier than any helicopter able to lift.
I asked you about their weights - you maintained Germany origin equipment.

Many kinds of options may be suggested for prompt response. But I think that decision making time much longer than transportation time by helicopters. So, no advantage.

 

[Dmytry]

Well, the cooling power requirements I (and you) can easily calculate, and then I can look up its weight.
http://en.wikipedia.org/wiki/File:Decay_heat_illustration2.PNG
60 minutes in, you have, let's say, <1.5% , which for 3GW thermal is 45 MW thermal.
http://www.wolframalpha.com/input/?i=75+bar+*+(45+MW+/+water+heat+of+vaporization)/water+density
150kw mechanical power to pump & cool by water boiling off, 750kw electrical should be plenty.
http://cfaspower.com/GTG_1366_Saturn_Mob.doc
7.5 tons for 750kw.
Big transport chopper lifts few tens tons.
Calculating fuel requirements and water requirements is left as exercise for the reader.

Decision making time: got to pre-decide what to do in event of cooling power failure.

 

[Joseph Chikva]

Decision making time: got to pre-decide what to do in event of cooling power failure.

But also situation should be monitored before, then - decide what to do. It requires much more time than needed for example to trucks.

If 7.5 tons yes - it easily can be transported by heavy-lift helicopters.

But which helicopter can carry a few tens tons?

 

[Dmytry]

But also situation should be monitored before, then - decide what to do. It requires much more time than needed for example to trucks.

You can't bring up pump power (not exactly difficult to monitor) - you look in SAMG - it says to call for external equipment - you do that. It's safety, man, you don't need to be so sceptical about worst cases, you don't need to wait for definite proof external equipment is necessary.
Versus assembling meeting of the top executives etc.

If 7.5 tons yes - it easily can be transported by heavy-lift helicopters.

But which helicopter can carry a few tens tons?

Mi-26 for example.
Natural disaster may damage road.

 

[Joseph Chikva]

You can't bring up pump power (not exactly difficult to monitor) - you look in SAMG - it says to call for external equipment - you do that. It's safety, man, you don't need to be so sceptical about worst cases, you don't need to wait for definite proof external equipment is necessary.
Versus assembling meeting of the top executives etc.

Mi-26 for example.
Natural disaster may damage road.

• Mi-26 can carry only two tens tons. And it is a big question undersling or in cabin.
• Super Stallion - up to 15
• Chinook - about 10

But when we have a task of carrying of big load, usage of Chinook is preferable thanks to its design - no main+tail rotors, but two main rotors. This design is less critical how far is the center of mass of load from helicopter's lift center.

 

[Dmytry]

How much it can carry depends to how much fuel it needs. Didn't really realize Mi-26 was so much bigger than all other alternatives (28 ton load+fuel)
In any case, a few choppers can deliver everything necessary for an accident that disabled power plant's electrical system and keep delivering the fuel (delivering the water might be problematic but a reactor ought to have a lot of spare water). The reactors cost multiple billion dollars each, right? And you need only a few such things for many reactors + the helicopters could be provided by military.
Furthermore, the reactor shouldn't really be kept at 75 bar operating pressure during emergency shut-down, right? Make it 7.5 bar and power requirements are 10x less.

Really, I think the biggest problem is the underestimate of risk of unforeseen circumstances. Tsunami is unlikely, terrorist attack is unlikely, sabotage is unlikely, etc etc but this stuff adds up and there's response that can be effective in the multitude of unforeseen circumstances - general ability to replace critical systems. Scepticism is good, but not extreme scepticism when evaluating possible disaster scenarios - instead one has to be sceptical of ability to predict.

edit: also, what is power/weight ratio of air coolers?
So far i can only find rates for small stuff:
http://www.megawavz.com/product.aspx?id=349572&desc=Price_SDVC5000_HVAC_Radiator
700L/s with weight of 32 lbs = 15kg.
the heat capacity of air at standard conditions is about 1.0 kJ/kg K (more at high temperatures), let's suppose we heat air up by 50 celsius, and let's suppose 1 litre of air weights 1.2 grams, 700 *0.0012 = 0.84 kg/s , 42KW cooling for weight of 15kg, so 15 tons for 40MW . 7.5 tons if we heat air up by 100 celsius.
I'd think larger unit would have better dissipation power / weight ratio.
I was really surprised this waste heat was such a big problem. 45MW is not a lot.

 

[Joseph Chikva]

How much it can carry depends to how much fuel it needs. Didn't really realize Mi-26 was so much bigger than all other alternatives (28 ton load+fuel)
In any case, a few choppers can deliver everything necessary for an accident that disabled power plant's electrical system and keep delivering the fuel (delivering the water might be problematic but a reactor ought to have a lot of spare water). The reactors cost multiple billion dollars each, right? And you need only a few such things for many reactors + the helicopters could be provided by military.
Furthermore, the reactor shouldn't really be kept at 75 bar operating pressure during emergency shut-down, right? Make it 7.5 bar and power requirements are 10x less.

Really, I think the biggest problem is the underestimate of risk of unforeseen circumstances. Tsunami is unlikely, terrorist attack is unlikely, sabotage is unlikely, etc etc but this stuff adds up and there's response that can be effective in the multitude of unforeseen circumstances - general ability to replace critical systems. Scepticism is good, but not extreme scepticism when evaluating possible disaster scenarios - instead one has to be sceptical of ability to predict.

Dmytry,
It is easy to calculate 20 tons or 28 tons when you see technical data of device or a few tens tons before seeing.
The problem is not in how we can search and find information or how we can add two numbers. I am a little bit familiar with helicopters and never heard about 28 tons load - minus some fuel. May be carrying of so big load for helicopters is bigger challenge?
And yes, may be disaster damage road. But why not landing near power plant. Why obligatory on the top?

 

[Dmytry]

Not obligatory landing on the roof. A minor safety feature for circumstances that preclude landing on the ground. Not very important, an proxy for safety conscious design.

The point is, this core cooling system loss - the power requirements are laughable. 45 megawatts, and they can't dissipate it with RCIC and some air cooled condenser, like, big HVAC. What the hell. Everywhere I look at nuclear industry, I see something similar to those 2 robots, one with consumer grade radiation monitor (by the look of it, no recording capability lol), other to take readings.

 

[Astronuc]

A couple questions.
1: Does US have anything similar to KHG? US robots on site in Fukushima - one with digital radiation monitor, other looking at first through camera - is that what US would use at US reactor accident? Is there a shortage / unavailability of such equipment for US-built reactors aboard?
2: Can the generators and substitute electrical equipment be quickly delivered on site by heavy transport helicopter in the event of failure of electrical systems like Fukushima (and successfully connected) ? Ditto for fuel and water. Ditto for pumps. So that all the critical safety equipment can be replaced with portable substitute. I know that German equipment is standardized and common industrial generators working at common voltages can be used to power cooling pumps. From Fukushima I know that they could not do this.
3: Why nuclear power plants don't have helicopter pads on the roofs just in case?

1. Yes - the US had robots since the early 1980's. Some are used routinely for inspection of irradiated areas, e.g., steam generators and the primary system.

http://www.iaea.org/Publications/Magazines/Bulletin/Bull273/27304393138.pdf (1985)

http://web.eecs.utk.edu/~parker/publications/Handbook99.pdf (1999)

EPRI has supported many remote inspection and service technologies on behalf of the nuclear industry, and the technology suppliers have developed their own proprietary systems. Some utilities have developed their own systems.

The US does enjoy a common AC frequency nationwide.

Heavy equipment can be brought to any NPP site in the US.

Based on Fukushima, utilities have been reviewing their plant designs for potential vulnerabilities, and their EOPs and SAMGs (severe accident mitigation guidelines).

 

[Dmytry]

1. Yes - the US had robots since the early 1980's. Some are used routinely for inspection of irradiated areas, e.g., steam generators and the primary system.

http://www.iaea.org/Publications/Magazines/Bulletin/Bull273/27304393138.pdf (1985)

EPRI has supported many remote inspection and service technologies on behalf of the nuclear industry, and the technology suppliers have developed their own proprietary systems. Some utilities have developed their own systems.

Good. Then WTF Japanese are doing with those two ibots?

The US does enjoy a common AC frequency nationwide.

Heavy equipment can be brought to any NPP site in the US.

But for that there needs to be a plan... the voltages must match, connectors, etc, the equipment must be ready for delivery.

Based on Fukushima, utilities have been reviewing their plant designs for potential vulnerabilities, and their EOPs and SAMGs (severe accident mitigation guidelines).

Well that's good to know. Pro nuclear people here (certain nuclear engineers supposedly) have almost got me convinced they see no need for ability to replace critical systems in the event of unforeseen circumstances, and argue against it.

 

[Joseph Chikva]

Not obligatory landing on the roof. A minor safety feature for circumstances that preclude landing on the ground. Not very important, an proxy for safety conscious design.

The point is, this core cooling system loss - the power requirements are laughable. 45 megawatts, and they can't dissipate it with RCIC and some air cooled condenser, like, big HVAC. What the hell. Everywhere I look at nuclear industry, I see something similar to those 2 robots, one with consumer grade radiation monitor (by the look of it, no recording capability lol), other to take readings.

I am afraid that information is dosed and consequently it does not correct absolutely to speak about "laughable" requirements.
Regarding offered by you helicopters pad I stay at the same - they won't add more safety.
Certainly, if you Dmytry is customer company and I – the company-contractor, on request for monitoring underwater environment I will provide you though a pocket submarine.

 

[Dmytry]

See, they have 3000MW dissipating equipment that was reduced to scrap metal because they did not have 45MW dissipating equipment. Think a little. UTTER ABSURD just like 2 robots one with radiation monitor other to look at it (unable to see through steam).

 

[Joseph Chikva]

See, they have 3000MW dissipating equipment that was reduced to scrap metal because they did not have 45MW dissipating equipment. Think a little. UTTER ABSURD just like 2 robots one with radiation monitor other to look at it (unable to see through steam).

I wouldn’t like to offend you. But everyone thinks himself as great strategist seeing the fight from outside.

 

[Dmytry]

See, I was asking specific questions here. Instead i get arguments like it being too heavy for #2 (ain't true) , the #3 being useless (ain't going to bother to argue), what ever, rationalizing lack of 1,2,3 even before absence is confirmed. That's the typical pro-nuclear behaviour.
Decay heat is nearly trivial (for a system of such operational power, I mean). Can be handled with very simple passive systems (ABWR and simplified BWR). Instead, in old reactors, relies entirely on electrical equipment that can sometimes be found in basement, never upgraded for passive cooling, no indication of well defined plans for response to failure, etc, a lot of apologism for that as well.

Someone asks about reactor uprating, they get told of turbine improvements etc etc, which aren't nuclear, an attempt is made to make it look as if reactor thermal power output uprating by ~7 percent was not common. Typical.
You know, you guys are actually far more effective than greenpeace at showing nuclear industry as unsafe.

 

[Joseph Chikva]

You know, you guys are actually far more effective than greenpeace at showing nuclear industry as unsafe.

From my side I have never said about nuclear power safety but at the same time I say that it has not any alternative. Frankly I was bothered to repeat the same in various variations. Greenpeace can jump up and down but everyone from that respectful organization uses the civilization blessings. This impossible without energy.
Regarding safety level.
It can not be infinitely high but should be reasonably high. As it connected with infinitely high expenses. And every project has limited budget. That's all.
Thanks.

 

[Dmytry]

The safety level can also be just as high as necessary to 'probably' (p<0.5) not suffer an accident in either of a hundred reactors of a particular design during the career of a person in charge of design. If you want nuclear power to have future - you'd better try and convince that the process ensures higher safety than this 'reasonably high' when http://en.wikipedia.org/wiki/Homo_economicus" in charge of the project is doing the reasoning for what safety is best for his own private benefit.
As a null hypothesis, I assume that the safety is in the ballpark of the optimum for people in charge / owners. That is, lifetime risk of severe accident on order of 1/100 .. 1/500 . I'm very curious what rates insurance companies charge nuclear reactor operators.

 

[traijan]

PRA Risk is usually greater then 1/100,000 reactor operating years. When approaching less the 1/10,000, operators will establish added boundaries to protect the site or shut down.

I believe insurance costs are typically 1 to 2 million a year per unit depending on the site. Contact them for more info:

http://www.nmlneil.com/

 

[Dmytry]

i've used NRC figures:
http://www.nrc.gov/reading-rm/doc-collections/fact-sheets/funds-fs.html
says 400K/year paid for single unit reactor site, covering 375M liability , giving a risk of >=375M accident on order of 1/1000 reactor years.
That is the estimate by companies that put their money on the table. I'm pretty sure someone would price cut if they thought the risk was 1/10 000. The risks - the problem is - suppose you analyse the plant, and you see risk of 1/50 000 by combining risks from various scenarios . What is the risk that you overseen some issue? Isn't it helluva lot bigger? Whats about all the potential issues you can't think up, which each is extremely low risk, but they all add up?

 

[traijan]

Note that it says 400k average. If your plant is in the middle of nowhere like Cooper in Nebraska I'm sure it is cheaper then somewhere like Indian Point right outside of New York City or San Onofre outside of LA/Orange County.

The risk I was referring to was the PRA risk which calculates Core Damage Frequency and Large Early Release probabilities. Essentially the probability if a major accident were to occur, what is the probability the core will melt of containment will be compromised and release radionuclides to the atmosphere. Maybe the risk that insurance companies define is broader in damage and account for any accident (ie fire, flooding, etc)

 

[Dmytry]

Note that it says 400k average. If your plant is in the middle of nowhere like Cooper in Nebraska I'm sure it is cheaper then somewhere like Indian Point right outside of New York City or San Onofre outside of LA/Orange County.

The risk I was referring to was the PRA risk which calculates Core Damage Frequency and Large Early Release probabilities. Essentially the probability if a major accident were to occur, what is the probability the core will melt of containment will be compromised and release radionuclides to the atmosphere. Maybe the risk that insurance companies define is broader in damage and account for any accident (ie fire, flooding, etc)

Well, its for liabilities... so it includes anything that nuclear power plant can be found liable for. Which is, incidentally, what I care about if I live next to plant. I don't really care if it just blows up on it's own, or it blows up due to flood. If anything, if i could trade it blowing up by itself for it blowing up during a disaster - i'd rather it blows up by itself, better to deal with nuclear accident alone than it superimposed onto tsunami, don't you think?

Really, the nuclear power plant accidents seem to be all or nothing affairs very much. Either almost no release, or a giant release. No level 6, two level 7.

 

[traijan]

Not according to the accident event sheet
http://www.iaea.org/Publications/Factsheets/English/ines.pdf .

And two major accidents in how many operating years worldwide with all the plants that have been online? Take the sum total of all the hours operating at full power. Compare this to all the oil refinery and chemical plant explosions, spills, releases, etc. And not to mention Coal fire plant pollution discharges, fires, acid rain, etc. Also, mind you that Nuke Plants are required to strictly monitor all effluent discharges for radiation, unlike coal plants that spew out large amounts of unmonitored radioactive releases and mercury and sulphur into the air.

http://www.scientificamerican.com/article.cfm?id=coal-ash-is-more-radioactive-than-nuclear-waste

I think in the end, if you want a stable grid with little emissions or environmental impact Nuke are still the safest and cleanest. All energy generation options have their tradeoffs and the goal is to mitigate and control these tradeoffs.

 

[Drakkith]

Do you have any answers? I am asking specific questions.

I gave you answers. If you don't like them, too bad.

For helicopter pad - auxiliary in the event that there's mess on the ground.

An auxillary pad in case there's a mess on the ground? I see where you would think this would be a good idea, but I don't think there would be any real benefit. If there is a mess on the ground then I see it as unlikely that it would be easier to unload heavy equipment from a rooftop.

So far I take your answer as "No and I don't think anything like that is necessary

That's because I don't see any benefit to your suggestions. I think about it, I compare the suggested use of it against the situations where it would be required, and usually I can think of several reasons why it actually isn't a very good idea to me. Like I said, if you are building auxillary helipads on top of bulidings just in case something on the ground happens, then would it actually be useful in an event like that? I don't think so. Why? Because of difficulties and complexities in loading/unloading equipment from the top of a building and because if the situation on the ground is so bad that you can't land a helicopter I don't see anyone getting any heavy equipment in there at all. Because of that I don't think it's a good idea to build it, not even to build it "Just in case". That's not the way safety works. You don't build random stuff just in case something might happen. You evaluate the possibilities, come up with REASONABLE solutions to those possibilities, and then design your safety off of that. I say reasonable in the sense that it isn't going to bankrupt your company to do these things. That very well might include building an auxillary generator building, or ensuring multiple backups of critical systems, or whatever. But none of those are built just in case something goes wrong. They are built for specific purposes in mind to protect against. I hope you don't misinterpret this as me saying I don't care about safety. Nothing could be further from the truth. What I don't care about is pointless excessive safety that impedes work or runs up costs without a valid reason.

 

[Astronuc]

According to WNN - Both units at the Surry nuclear plant in Virginia shut down automatically as designed when a tornado touched down at the plant's switchyard, cutting off external electricity connection. Backup diesel generators started up immediately to provide the necessary power to keep the two pressurised water reactors in a safe and stable condition. Off-site power was subsequently restored.

Both units are still down pending repairs to equipment.

A tornado (high wind) is one of the natural phenomena that plant designs must concern, even if it is a low probability event.

When hurricane approaches the east coast, plants will go to hot zero power or hot standby, just in case they loose off-site power connection.

 

[Astronuc]

Someone asks about reactor uprating, they get told of turbine improvements etc etc, which aren't nuclear, an attempt is made to make it look as if reactor thermal power output uprating by ~7 percent was not common. Typical.
You know, you guys are actually far more effective than greenpeace at showing nuclear industry as unsafe.

No attempt was made here to "make it look as if reactor thermal power output uprating by ~7 percent was not common".

The low power density units can increase power by up to 20%, and some operated on 24 month cycles. The highest power density units are generally limited to about 7% uprate, and they remain on 18 month cycles. I know of one plant that increased the core power by 5%, but then optimized the core design to reduce power peaking, to the peak local powers and burnups are actually less than when they operated at lower power.