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

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

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?
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

I am asking the question, whenever there is such capability? Until i get 'no' i am not asking why there isn't.
Ohh right and then they couldn't power even the spent fuel pool pumps. Meaning the did not have this capability.
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.
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:De...ustration2.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...Fwater+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

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

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.

Joseph Chikva

• 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..._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), lets suppose we heat air up by 50 celsius, and lets 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

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

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/Mag...7304393138.pdf (1985)

http://web.eecs.utk.edu/~parker/publ...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

Good. Then WTF Japanese are doing with those two ibots?
But for that there needs to be a plan... the voltages must match, connectors, etc, the equipment must be ready for delivery.
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

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.