Friday, July 30, 2010

The Big Lots Reactor Revisited

I first discussed the Big Lots reactor concept over a year ago. Lowering energy and nuclear costs is a persistent focus of Nuclear Green, and the Big Lots concept grew out of that focus. In March of 2009, I suggested:
The most important questions which we need to answer about thorium cycle/LFTR technology are:
1. Can it be built at a reasonable cost?
2. Is is scalable enough to meet our energy needs?
3. Can we complete world wide deployment of carbon technology replacing LFTR by what is often seen as the cut off date of 2050?
I responded to my own question
Perhaps my only original idea about Liquid Fluoride Thorium Reactor (LFTR) design was more a marketing suggestion, which combined David LeBlanc's suggestion that capital costs for LFTRs could be lowered by using lower cost materials that would tolerate somewhat lower reactor performance. David LeBlanc's suggestions indicated that low cost LFTRs could be built from commonly available low cost materials. I saw that this would solve a major problem in all current plans to produce post carbon electricity, that is the absence of a low cost load following and peak reserve electrical production technology to replace natural gas. Indeed the Greenpeace "energy [r]evolution" plan is not a true post carbon energy plan because it calls for an increase in the capacity of natural gas powered generating facilities over the next 20 years in order to supply load following and peak energy capacity to the grid as a compensation for the increased penetration by wind powered generators.
So the basic Big Lots idea was to build reactors with low cost materials, that will not compromise safety provided a somewhat lower level of performance. It first should be noted that lowering performance does not mean poor efficiency. In the Big Lots performance is lowered is several ways. First the operating temperature is lowered to a lower temperature that can be tolerated by steel. Secondly, the reactor would not be expected to operate on a full time basis. This would extend core component life, since the core components would not be subject to neutron radiation much of the time. Thirdly the reactor would be expected to operate at less than full power during much of the time it is actually producing power.

Performance compromises are relative. Even a lower performance LFTR will still operate at a higher temperature that an Integral Fast Reactor, thus the overall efficiency of the Big Lots reactor would not be compromised. Conventional reactors are designed to operate at peak power and efficiency almost all of the time, but the demand for electricity from the grid constantly varies, with electrical demands typically peaking during the daytime, and dropping back at night. Rather than build a lot of high cost nuclear and coal fired power plants to produce peak demand electricity, the electrical utilities have during the last generation to natural gas powered turbines. In addition, natural gas turbines can be ramped up quickly. This makes them excellent rake up and reserve electrical generating capacity. Natural gas turbines are also easy to throttle. Thus they are useful for following load demand on the grid, or in balancing the variable electrical output of renewables. Natural gas is an expensive fuel, but concepts such as combined cycle generations have made natural gas powered plants more efficient. Utilities are willing to pay more for peak electrical generation capacity, and natural gas fired electrical generation turbines and combined cycles generation plants have lower capital costs than coal or nuclear generation facilities. The cost of natural gas fluctuates over time, and typically electricity produced with natural gas is more expensive. Of course the use of natural gas also increases global CO2 emissions, although not as much as coal. The Big Lots idea is to come up with a low cost carbon free substitute for natural gas peak demand, load following, backup and reserve electricity generation.

The Big Lots reactor could do everything a natural gas powered generation unit can do, without CO2 emissions. If the price of the Big Lots reactor can be kept low enough, it can be economically quite competitive with natural gas, even if its overall capital costs are higher, because fuel costs would be lower than that of a natural gas powered unit. Even if the Big Lots were not designed to be a breeder, this could still be the case. In addition to lower fuel costs, the cost of the Big Lots would be less, as I note,
operating LFTR on a partial power or a part time basis decreases neutron damage to core material. At the same time load following power and peak load power is purchased by utilities at a premium price. It appeared to me that there was a potential for synergy here.
And the operations of the Big Lots creacto can potentially be profitable because,
load following power and peak load power is purchased by utilities at a premium price.
Big Lots Reactor price can be lowered by factory manufacture,
Production of the Big Lots Reactor would be highly scalable because it is factory built. The production process can use labor savings machines at every stage of the production process. Given a large enough production volume, parts manufacture can be partially or even completely automated. Robots can replace workers in some assembly operation. It is anticipated that the factory produced Big Lots will be shipped to the reactor site for final setup in modular units. Labor savings equipment can be used in site preparation, component assembly and in finishing off the site.

The Big Lots factory would be large, but not larger than a modern aircraft assembly factory. Component modules need not be produced in the same factory. The modules would be major reactor components. The assembly of the modular components should be relatively simple and quick, with most of the assembly being performed in factory settings.
My original Big Lots post triggered a discussion on Energy from Thorium discussion in March 2009. That discussion is still echoed in more recent EfT discussions. Skinny Dog wrote a couple of weeks ago,
his low-temperature / common materials approach reminds me of what Charles Barton calls "Big Lots" reactors. You should hook up with him on the idea. I think it's a good 'un.
Good or no, the Big Lots approach is not the only way the peak load, reserve power problem can be solved, using molten salt technology. A Molten Salt Reactor is a big salt heating device, and with Solar thermal power, once liquid salt is heated, it can be stored, and then produced when energy is demanded. Thus if surplus heat produced by a LFTR or other MSR - surplus heat being heat not required by current energy demand, - then the excess energy can be stored as hot salt. When energy demand increases beyond immediate reactor generation capacity, hot salt can be withdrawn and its energy turned into electricity by a closed cycle gas turbine or Sterling engine.


Christopher The Painter said...

LOL! Nice blog name. The Nuclear Green Revolution. Isn't that kinda anti-climatic? Nuclear and going green...

Isn't nuclear energy also bad for the environment. O_o

Charles Barton said...

Christopher, One of the most dangerous myths of the environmental movement is that nuclear power is bad for the environment, In fact nuclear power generation itself emits no CO2. Nuclear power plants emit tiny amounts of radioactive material, far less than is naturally present in the environment. Renewables do far more environmental damage. For example the process of building a large Solar Thermal Power Plant begins by bulldozing several square miles of soil in environmentally sensitive desert habitat. Solar Thermal plants also use a huge amount of scarce desert water.

Rick Maltese said...

Hi Charles

I personally think this idea is brilliant. Liked it the first time and even better now. It's such a dense energy that scaling down is feasible and even sensible. If nothing else it demonstrates that all competing forms of energy don't have the luxury of scaling down to meet requirements.

Charles Barton said...

Rick, i consider the Big Lots concept to be my most original contribution.

Rick Maltese said...

Hi Charles

Was thinking about a scenario where a "Big Lots" reactor is being used and through poor forecasting or unexpected failures that the demand on the reactor would be boosted. We know that theoretical limits and best case procedures would be recommended but have you given much thought to the need for customizing built-in limits. In other words making it impossible to surpass a specific threshold of output to ensure the life of the reactor or do you see this as a minor problem and replacing worn out parts would just happen when they're needed.

Charles Barton said...

Rick, the "Big Lots" idea is that you need a lot of part time generation sources for peaking power, or for reserve for seasonally related electrical demand, for example summer electrical demand for air conditioning. The ideas is to build the part time reactors as cheaply as possible, with the expectation that they will only be working part time, and thus would receive less radiation damage. If the designed in use limits are exceeded, the reactor won't last as long. Since peak power is the most expensive, the "Big Lots" reactor runs on a different economy than a base load reactor.


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