Wednesday, May 6, 2009

Adjusting to the LFTR on the Grid

Compared to LWRs, CANDU reactors tend to require reconstruction every 25 years. LWRs maintain interior pressure by means of an exterior pressure vessel, what is not exposed to high levels of neutron radiation. The CANDU reactor uses internal pressure tubes, and they are damaged through high levels of exposure to neutron radiation. Every 25 years CANDU reactors require expensive rebuilding to replace radiation damaged parts.

Radiation damage to core parts is also a potential problem for the Liquid Fluoride Thorium Reactor (LFTR). This problem would be most acute, were the LFTR used in a base power generation role like LWRs. But in a grid with a high level of nuclear penetration, rhe reach of nuclear power, and in particular the use of LFTRs may extend far beyond the base load role of current technologies. Indeed if LFTRs are confronted with limited core life, it would be in the interest of LFTR owner/operators to utilize the limited LFTR core life to maximize profits. That would mean limiting LFTR operations to periods when electrical generation receives the most favorable rate of return. Given limited core lifetimes, It would not be rational to sacrifice limited core life, when electrical generation pays only a small return.

Light Water Reactors are capable of operating 90% of the time over a period of 60 years without major core rebuilding. High initial capital investment is repaid by continuous operation year in and year out. In contrast, continuous operations with lower rates of return would not be rational for LFTRs with limited core lives.

Thus LFTRs may be dedicated to none base load functions on the grid and profitably so. LFTRs might perform a variety of part time and part load assignments, including mid load 16/7 and 16/5 power generations, peak load generation and and load balancing. The LFTR offers ideal candidacy for spinning reserve, since it can produce maximum power almost immediately from a full stopped operational mode, something no other electrical generation technology can perform. In addition to operating part time, LFTRs can be normally operated at partial power, since operating at partial power is another way to increase core life. The presence of numerous LFTRs, each operating at say 50% of maximum capacity offers a significant cushion against sudden grid shutdown. The added power demand will quickly pull the LFTR into full power operating mode. LFTR operators wold be compensated for a shorter core life due to maximum power operations, by increased compensation for back up power.

LFTR designers will also have to think of LFTR designs for non-base load operations. Maximum efficiency may not be as desirable as low capital cost and reliability in the face of rapidly changing electrical demands.

4 comments:

donb said...

The loading of power generation sources has long been determined by the economics, basically, the lowest cost sources are the first to supply any additional power, and as they are max'ed out, the sources with the next higher cost take the load.

I don't think this is going to change with the LFTR. Economics of operation will still rule. Even with two or more available LFTRs serving one load area, there will still be one with the lowest marginal costs, which will be the first one to be fully loaded. In may cases, this means that source is supplying baseload power, and so it operating at 100%, 24 by 7.

There are other considerations, such as spinning reserves, which may cause operators to begin dispatching more expensive generation sources before the least expensive ones are fully loaded, but in the main, economics rule.

I think key for the LFTR is to make the moderator easily swappable. Even LWRs are shut down every 18 months or so for fuel swaps, which is a routine part of their operation.

David Walters said...

donb makes excellent points and I agree.

The appeal of the LFTR is that it can end up dominating *any* market for generation, be it baseload, intermediate load following:
1. frequency correction as dictated by SCADA.
2. load following as dictated:
a. AGC response to system demand.
b. ISO dispatch
c. Day ahead/hourly ahead/10 minute ahead scheduling.
3. peak loading from a cold standby or lower loads.

Either units can be designed around these criterias or any LFTR can do all 3 areas of work. THAT is the appeal.

David

All these

Charles Barton said...

Among the determinants of cost is the rate of return investors want to see on their investment. In a perfectly competitive market the LFTR owner would be forced to provide electricity at what ever price the market was willing to pay. However it is doubtful that there will be so many LFTRs providing reserve electricity that anything like perfect competition will exist among them. Hence LFTR owners are likely to have at least some power to negotiate price with electricity distributers.

David Walters said...

Due to the nature of the grid, even in the most free-market scenerios, RMR contracts will still provide the majority of baseload and even peaking load scenerios. If not RMR then very flexible day-ahead and 10 min. incremental contracts. I can't see everything "up for bid" at least not for base load, which is handled now, but both RMR contracts (basically year contracts for being *available* for loading) and day ahead markets. Sometimes plants can have *part* of their load capacity put toward various segments of the market, like 50% RMR the rest divided between day ahead and say, hourly.

The point is that the LFTR can handle this stuff pretty easily, regardless of how it is dispatched.

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