Electricity Output of Gen 2 & Gen 3+ Reactors

[aquitaine]

Of the typical generation 2 reactor in service today, in percentage terms how much of the energy produced by the reactor is turned into electricity? What about new Generation 3+ reactors (such as the AP 1000)?



Thanks.

 

[mgb_phys]

PWR about 35%
AGR about 40%

 

[aquitaine]

5% improvement? Doesn't seem like that much on the surface. Of course any improvement in efficiency is welcome.

 

[Astronuc]

At the temperatures used in a typical PWR the thermal efficiency has been about 32-34% typically. Some plants have had their turbines replaced with more efficient designs and some current PWRs attain ~35-36% thermal efficiency. I believe AREVA expects about 35-36% efficiency with the EPR, while Mitsubishi has mentioned ~37% (although one citation mentioned 39%). I believe the AP1000 is expected to attain ~35% gross efficiency (~33% net if cooling towers are used for cooling).

British Energy has a comparison. They AGR may achieve up to about 42% thermal efficiency.
http://www.british-energy.com/documents/Different_types_of_nuclear_power.pdf

 

[gmax137]

5% improvement? Doesn't seem like that much on the surface. Of course any improvement in efficiency is welcome.

The thermodynamic efficiency (or plant "heat rate") is determined by the temperatures of the steam and condenser, along with the sophistication of the secondary plant equipment. Since most power reactors produce saturated steam, the efficiency is going to be lower than that obtained by a superheat fossil fired boiler. The exception is the B&W once-through steam generator, which produces a little bit of superheat. That design is not without its own problems.

Second, remember that the fuel cost in a nuclear unit is a minor contributor to the overall generating cost. That means that improved thermo efficiency does not reduce the cost the way it does for fossil units (where fuel cost is the major contributor to the total cost). Since uranium has no other use, "wasting" a little bit in the "low efficiency" nuclear unit really doesn't matter much.

Finally, "any improvement in efficiency is welcome" is only true subject to the financial costs associated with the improvement. The power company will do a cost-benefit analysis to determine if they should make improvements in the secondary plant (new feedwater heaters or MSRs; replace/rework the HP and/or LP turbines, etc). For them, it all comes down to dollars & cents.

 

[mgb_phys]

One thing I did always wonder.
In europe at least, coal fired stations have huge cooling towers even though they are normally on rivers (the only economic way to get 1000s of tons of coal/day). While nuclear stations are almost always built on the coast and use water cooling.

Originaly the reactors were built on the coast for safety well away from big cities. Or it's a shear coincidence that France built most of it's plants on the north coast facing Britain and Britain built them in the north of England or Scotland.

Since in both cases you want the maximum cooling to increase the efficency? Is it just that with modern coal stations you don't use cooling towers either, it's just that they were originally built 30-50years when cooling towers were the best solution. Or is it that you don't want the nuclear statiosn to have any more visible impact than is necessary - to reduce public objections.

 

[gmax137]

The cooling towers are needed when regulations limit the temperature increase between intake and outfall into the river or bay or whatever. Whether the towers are needed depends on local/state/federal regs in place at the time the plant was built/licensed, not so much on whether it's a nuke or a dirt burner.

Many people think that the nuclear units' remote location was safety consideration (and to some extent that was true in the early 1960s) but don't forget that the fuel is cheap and easy to transport to remote locations. That's certainly not true for coal. So if the grid needs a generator way out in the woods, a nuclear unit fills the bill. Instead of a continuous flow of coal cars on a heavy rail line, all you need is a coupla dozen semi-trucks once a year and a paved road...

 

[mgb_phys]

But you do need reasonable access to build the place and if that were true you would put the coal fired stations on the coast, not inland next to the cities they supplied.

The cost of building cooling towers is a tiny part of the plant costs so that can't have been a driver for putting them on the coast. France had a problem in the summer when several of it's nukes on rivers had to be shut down because of cooling limits.

Do they still build cooling towers for modern coal stations? In the UK all new power plants in the last 20years have been gas and relatively small so no need for towers.

 

[gmax137]

The cost of building cooling towers is a tiny part of the plant costs

Actually the cooling towers are very expensive.

France had a problem in the summer when several of it's nukes on rivers had to be shut down because of cooling limits.

I thought it was low water level in the river, but I could be wrong.

Do they still build cooling towers for modern coal stations?

Yes. Well, in the US they do.

 

[Astronuc]

But you do need reasonable access to build the place and if that were true you would put the coal fired stations on the coast, not inland next to the cities they supplied.

There's a trade-off. Ideally the plant is closest to the load/demand, which means inland near cities (population centers) in order to avoid transmission losses (and minimize reactance). That requirement has to be balanced with the environment and available heat sinks.

Another consideration is the requirement for exclusion zones around nuclear power plants. It's much easier to build NPPs in remote areas and not have to deal with evacuation plans of hundreds of thousands or millions of people. Coastal areas (away from ports) tend be remote.

The cost of building cooling towers is a tiny part of the plant costs so that can't have been a driver for putting them on the coast. France had a problem in the summer when several of it's nukes on rivers had to be shut down because of cooling limits.

I believe those plants had cooling towers. They are large structures and do represent a not too insignificant portion of capital cost.

Do they still build cooling towers for modern coal stations? In the UK all new power plants in the last 20years have been gas and relatively small so no need for towers.

That depends on the plant capacity. In the US as well, new plants tend to be gas-fired (gas turbine or combined-cycle) of low unit capacity. They have been primarily peaking units, although with inexpensive gas they could be base-load units.

Some modern coal-fired plants could use coal gasification and incorporate combined cycle to reduce the waste heat load.

 

[mgb_phys]

They are large structures and do represent a not too insignificant portion of capital cost.

Oh, these towers are amazing bits of engineering they are very thin and contain very little concrete. I assumed they were pretty cheap to build (once you had been doing it for 70years)

 

[Astronuc]

Oh, these towers are amazing bits of engineering they are very thin and contain very little concrete. I assumed they were pretty cheap to build (once you had been doing it for 70years)

That's a fair amount of steel and concrete, and the cost of those commodities has gone up. In addition, the sap about 2% of the plants thermal efficiency. One has to pump the water and blow the air (force draft).

Update:

Currently, of the USA's total of 104 nuclear power reactors, 60 use once-through cooling from rivers, lakes or the sea, while 35 use wet cooling towers. Nine units use dual systems, switching according to environmental conditions.

http://www.world-nuclear-news.org/RS-Cooling_tower_requirement_for_Oyster_Creek-0801104.html

 

[mheslep]

5% improvement? Doesn't seem like that much on the surface. Of course any improvement in efficiency is welcome.

That additional 5% on a single 1GW(e) reactor will run 25,000 to 50,000 more homes.

 

[Astronuc]

That additional 5% on a single 1GW(e) reactor will run 25,000 to 50,000 more homes.

While getting some improvement from more efficient turbine sets, most nuclear plants are looking at uprates or increases in thermal power - anywhere from 5% to 20% of original design.

Shaw eyes US reactor uprate market
07 January 2010

An increasing number of US utilities are opting to increase the generating capacities of their existing nuclear power reactors, creating a $25 billion market, according to the Shaw Group.

While making a presentation of company results, Shaw's chairman Jim Bernhard said that 37 reactors out of the USA's total of 104 had already completed or were in the process of implementing power uprates. He added that Shaw had participated in over half of these uprates, helping to add over 3000 MWe to the grid - roughly the equivalent of three new reactors.
. . . .
According to the US Nuclear Regulatory Commission (NRC), which must approve changes in engineering at nuclear power plants, a survey of reactor licensees in May 2009 indicated that some 40 applications are likely to be submitted to the NRC over the next three years for power uprates totalling about 2075 MWe of new generating capacity. During 2010, 16 more applications are expected for uprates that will add a total of some 965 MWe of capacity. A further 17 are expected in 2011, representing an additional 548 MWe, followed by 7 applications in 2012, adding 562 MWe.

This expected total comes to 4150 MWe of new nuclear capacity in the USA - almost as much as three or four new reactors could provide.

http://www.world-nuclear-news.org/C-Shaw_eyes_US_reactor_uprate_market-0701104.html

 

[mheslep]

most nuclear plants are looking at uprates or increases in thermal power - anywhere from 5% to 20% of original design...

Yes I'd seen that - 'uprates'. Essentially ~4 new reactor power equivalents all under the radar of the nuclear critics. That's all to the good, except that I don't care for the double standard at the NRC: immediate approval of uprates, but new reactors or designs are slow walked or ignored forever.

 

[Astronuc]

Yes I'd seen that - 'uprates'. Essentially ~4 new reactor power equivalents all under the radar of the nuclear critics. That's all to the good, except that I don't care for the double standard at the NRC: immediate approval of uprates, but new reactors or designs are slow walked or ignored forever.

The new plants are not being ignored. There's a lot going on behind the scenes.

 

[mheslep]

The new plants are not being ignored. There's a lot going on behind the scenes.

I'd argue that some of these new designs are being ignored, like the small reactors discussed in this forum, and I'd argue that the main stream new PWR plant proposals are being slow walked. Some ~17 plant proposals submitted - years ago - and not a single plant breaking ground. I saw the FP&L CEO interviewed the other day - he stated the NRC takes about 42 months to review a proposal for a new plant - after which they still can (and do) say no. Compare that to the speed with which uprates go through.

 

[Astronuc]

I'd argue that some of these new designs are being ignored, like the small reactors discussed in this forum, and I'd argue that the main stream new PWR plant proposals are being slow walked. Some ~17 plant proposals submitted - years ago - and not a single plant breaking ground. I saw the FP&L CEO interviewed the other day - he stated the NRC takes about 42 months to review a proposal for a new plant - after which they still can (and do) say no. Compare that to the speed with which uprates go through.

The NRC is still working on the certifications - and recircertification of the ABWR, since GNF/Hitachi parted ways with Toshiba. And all parties are working on resolving some issues with the new plants. And the small plants are not forgotten - they just got a late start.

 

[joelupchurch]

I'd argue that some of these new designs are being ignored, like the small reactors discussed in this forum, and I'd argue that the main stream new PWR plant proposals are being slow walked. Some ~17 plant proposals submitted - years ago - and not a single plant breaking ground. I saw the FP&L CEO interviewed the other day - he stated the NRC takes about 42 months to review a proposal for a new plant - after which they still can (and do) say no. Compare that to the speed with which uprates go through.

I've argued in other places that the incredibly long licensing times are the biggest impediment to building new nuclear power plants in the United States. It makes no sense at all that is should take so long to approve a new plant when the designs have already been approved by the NRC.

As it stands now, the Chinese will have Westinghouse AP1000 reactors up and running before we start construction on our first one. The first one is supposed to go online in 2013.

BTW the AP1000 has already been uprated from 1175MWe to 1250MWe because of new turbine designs.

http://www.world-nuclear.org/info/inf63.html"

 

[Astronuc]

I've argued in other places that the incredibly long licensing times are the biggest impediment to building new nuclear power plants in the United States. It makes no sense at all that is should take so long to approve a new plant when the designs have already been approved by the NRC.

As it stands now, the Chinese will have Westinghouse AP1000 reactors up and running before we start construction on our first one. The first one is supposed to go online in 2013.

BTW the AP1000 has already been uprated from 1175MWe to 1250MWe because of new turbine designs.

http://www.world-nuclear.org/info/inf63.html"

Note that Mitsubishi is supplying the turbines - they are not from the US. Westinghouse exited the large turbine business a while ago.

In April 2007, Westinghouse signed a $350 million contract with Doosan Heavy Industries in Korea for two pressure vessels and four steam generators for Sanmen 1 and Haiyang 1. The pressure vessels for the other two units are being made by Chinese manufacturers: China First Heavy Industries (CFHI, also known as YiZhong) for Sanmen 2 and Shanghai Electric Group Corporation (SEC) for Haiyang 2. Steam generators for Sanmen 2 and Haiyang 2 are being manufactured by Harbin Power Equipment Co., Ltd. (HPEC) and SEC, respectively.

All four steam turbine generators are being manufactured by Mitsubishi Heavy Industries (MHI). In a $521 million deal, Sanmen Nuclear Power ordered two turbine generator packages from MHI at the end of September 2007, with Shandong Nuclear Power ordering another two early in 2008. MHI's Takasago Machinery Works is manufacturing the turbines, including rotors and blades. Mitsubishi Electric Corporation is supplying the generators and HPEC, partnering with MHI, is responsible for turbine casings, piping and associated facilities. The turbines will reportedly boost the capacity of the reactors from their designed 1175 MWe to 1250 MWe gross.

Mitsubishi is competing with Toshiba/Westinghouse to sell new NPPs in the US.