Ni-Cd Batteries in Nuclear Power Station 9

[hassankh]

Most of the Standards like IEEE 535 and IEEE 666 talk about Lead-Acid batteries for nuclear power plants. Also, as far as I know, several modern nuclear power plants currently under construction also plan to use Lead-acid batteries. However, as we all know, recently Ni-Cd batteries have gained so much interest in other industrial applications. I wonder if Ni-Cd batteries have any particular characteristic preventing their use in NPPs?
Thank you in advance
Best Regards

 

[MikeHalloran]

Ni-Cds are perfect for starting the helicopter that you would use to bug out.

Mike Halloran
Pembroke Pines, FL, USA

 

[ScottyUK]

One consideration would be the enormous cost of Ni-Cad batteries in the sizes typically employed at a nuclear power plant. The largest commercially-available Ni-Cads are also significantly smaller in capacity than the largest flooded lead-acid cells.

 

[hassankh]

Is the cost and capacity the only deciding factor? what about safety?

 

[abbas2005]

Ni-Cd batteries Hydrogen gas emission is considerably less than Lead-Acid batteries.
Also Ni-Cd batteries are better choice because of their long life time, reliability and low maintenance cost.
I'm agree with ScottyUK about Ni-Cds enormous cost and smaller size with respect to Lead-Acids.

 

[krisys]

I would like to add to "abbas2005" view as below:

a) The capacity drift (reduction in capacity) due to the high temperature is very less as compared to Lead Acid Batteries. So where there is a high ambient temperature application is required, Ni-Cd batteries are preferable choice.

b) The negative side of Ni-Cd batteries is that it is not considered as environment friendly. Cadmium is difficult to dispose at the end of batteries useful life.

 

[Zogzog]

Nuke plants do not like changing things, takes forever to get something new approved and procedures developed.

 

[MikeHalloran]

One more Ni-Cd negative; they don't like 'float' service. I.e., take a small fraction of C out of a Ni-Cd, recharge, and repeat, and the cell's usable capacity tends to drift toward that small fraction of C that you use.

Ni-Cds thrive in heavy service, as I said before, like starting a helicopter. They are typically sized to drag that big ol' rotor and the engine up to starting speed, exactly twice, after which they are dead. So long as the onboard charger is working, and runs long enough to bring the battery to full charge, the NiCd battery will maintain most of its capacity for years of starting, even many times a day.

A Ni-Cd is not such a good choice for, say, your car, where the engine usually starts instantly, so the battery is not working very hard most of the time.


I have no idea what a nuclear plant's demand on batteries would look like, but basically, if you don't beat the crap out of them regularly, you won't be happy with NiCds.






Mike Halloran
Pembroke Pines, FL, USA

 

[davidbeach]

I'd guess the battery duty would be a lot like it is at a large substation or a conventional power plant - the charger carries the DC load almost 100% of the time. But when there's no AC into the charger or the DC load suddenly becomes vastly larger than normal, well that's not a good time for the battery to decide it doesn't want a deep discharge.

 

[MatthewDB]

The only major difference between nuclear duty and substation duty would be the sheer number of power circuit breakers and their charging motors at a nuke plant.

 

[ScottyUK]

The tripping & control batteries almost certainly aren't the awkward ones - it will be the massive batteries used for the turbine auxiliaries and in some stations also the gas circulators. Capacities of several thousand Ah at 110V or 220V aren't uncommon.

 

[racookpe1978]

"The advantages" of a NiCd battery for transportation go away in a nuke plant: Weight? Who cares? Size? Again, basically - it doesn't matter since the battery storage area is so small compared to everything else. Large, heavy lead acid batteries on a concrete floor in a building within the fence are nearly trivial in the total site plant. Reliable long-term float at 1% "load" then a sudden need to discharge to near 100% capacity (power loss and scram and emergency cooling) are the reason the batteries are there: Carry the DC loads and invertors until the diesels startup and carry it.

Disadvantages of NiCd outweigh the size advantage.

 

[hassankh]

Thank you all for your insightful guidance.
The major conclusion I believe is that Ni-Cd is not reliable enough to provide a complete discharge which is critically needed in NPPs during loss of AC power or blackout.