ARIES Documents

Utility Advisory Committee Reports

BACKGROUND

With the fusion program entering the fusion power production era, the direction and outcome of research over the next decade will have a large impact on the performance and characteristics of the fusion Demo and of commercial fusion power plants. At the same time, a major goal of fusion power plant research is to identify directions towards attractive commercial systems. As such, it is an essential part of this work to incorporate the requirements of the end-user (i.e., utilities).

To this end, the fusion power plant studies program has formed a Utility Advisory Committee consisting of senior executives from several U.S. utilities. (A list of the committee members is attached.) The Utility Advisory Committee is asked to provide input in three broad areas:

(1)Generic issues regarding the organization and requirements of the future utility supply industry. Such issues include whether utilities are distributor or plant owners and operators, the size of base load plants; concerns regarding mix of energy sources; the nature and security of fuel supplies; the role of environmental and safety characteristics, goals and directives; and the requirements of licensing.

(2)Fusion development issues related to plant development pathways to the fusion Demo (e.g., requirements of the fusion Demo, timing appropriate to major utility participation, timing appropriate for industrial plant suppliers taking full leadership of fusion development, etc.).

(3)Power plant issues related to the design and operational requirements of the power plant, issues which can be addressed in the context of conceptual designs such as ARIES and PULSAR (e.g., maintenance, availability, maintainability, etc.).

The first meeting of the fusion power plant program's Utility Advisory Committee was held at UCLA on May 21, 1993. Attending were Warren Fujimoto (Pacific Gas and Electric), Steve Rosen (Houston Lighting and Power) and John Stringer (EPRI). Background information on fusion research was presented and the discussion focused mainly on two generic issues: the organization and requirements of the future utility supply industry; and the general approach that the fusion community should take in order to present fusion as an attractive future energy option. A synopses of the meeting follows.

GENERIC ISSUES

Nature of utility supply industry

The nature of utilities is changing rapidly. Originally, utility companies were formed and regulated in order to ensure a reliable supply of electricity. As such, utility companies were plant owners and operators as well as distributor of electricity. This picture has been evolving during the past few years due to the changes in the laws governing utility companies and in particular independent power producers. Present law aims to promote competition in order to reduce costs. Most utilities are now required to purchase power from independent power producers (with favorable terms in some cases). It appears that the direction is for utility companies to become the distributor of electricity to their markets. The company is likely not to own and operate new plants. A utility company will, however, be allowed to own a subsidiary which builds and operates power plants in a market serviced by another utility company. The reaction of utility companies to all this is somewhat mixed right now. Some are rapidly embracing this new concept while others have concerns regarding the reliability of independent (and small) power producers.

Mixed Sources of energy

At present, in addition to cost-based justifications needed for new plants, a utility company strives for a mix of energy sources in order to insulate itself and its customers from drastic changes in the marketplaces (e.g., oil price shock). Current projections indicate that coal supplies will last about 100 years and natural gas about 50 years. Some projections indicate that Advanced Light Water fission reactors may be ordered around 2005. Uncertainties are many, including the outcome of the CO2 and global climate change debate, and whether nuclear power again becomes acceptable. Fusion development, having an operating DEMO around 2025, is beyond the time-frame examined by most utilities. As a result, utility companies are not interested now in having a major role in the fusion program.

Plant size and Siting

The unit size of power plants desired by utilities depends on the size of the utility, on regulatory and consumer attitudes in its area, on the desired proximity of plant and customer, and on the grid connecting the utility and its neighbors, among other things. Unit size should not exceed about $\sim$7\% of the utility grid size and the capital cost should likewise be of a scale that fits the utility. We were given two very different examples. Pacific Gas and Electric projects plants to be sited near population centers, using existing grids, and minimizing the distance between power production and power consumption centers. This company favors small plants of about 300~MWe. Houston Lighting and Power projects more remote siting (because the company has adequate space available), and a large and expandable grid. They would favor plants as large as 2000~MWe. Both utilities emphasized that they now have excess capacity and are not building plants of any size.

Many other issues affect the choice of siting for a power plant. These include: (1) the cost of land and taxes; (2) proximity of major populations (i.e., requirement for and complexity of any emergency evacuation plan); (3) the distance between the plant and the consumers; (4) the electric grid needed to transport the power; and (5) coolant availability.

Fusion has potential advantages in at least three areas with respect to fission. First, fusion plants may not require an emergency evacuation plan. This would lift a major regulatory burden and permit plants to be sited nearer to population centers. This in turn produces great savings in the cost of distribution. Fusion plants have the potential to achieve this advantage by the development and use of low-activation materials and by reducing the tritium inventory in the plant. Second, water (for reject heat) is always an issue and the ability to employ dry cooling would be a plus. ARIES designs which use high-temperature steam Rankine cycles and designs which use gas turbines are preferable from this point of view. Fusion plants can produce the high temperature operation needed to achieve this advantage. Third, except for the initial start-up fuel supply, fusion plants have a completely closed fuel cycle at the power plant. Radioactive fuel is not shipped to or from the reactor site, and there are no separately sited fuel reprocessing plants.

FUSION DEVELOPMENT ISSUES

Discussion of fusion development issues were focused mostly on directions to gain acceptance of fusion in the electricity-production market place.

Fusion acceptance

It was strongly emphasized that in addition to utility companies, three arenas must be influenced to gain acceptance: (1) regulatory, (2) political, and (3) the public. The reaction of these three groupings will strongly impact utility acceptance of fusion plants.

Potential features of fusion plants that would elicit a strong positive response from utilities are: (1) no high level waste is produced; (2) there is no need for an emergency evacuation plan; and (3) there is a secure, dependable fuel supply without requirement for transporting large amounts of fuel (especially radioactive fuel) to and from the plant.

In the political and public arenas, the advisory group saw it as an imperative to draw a distinction between fusion and fission. For example, one should seriously consider the negative impact of words like "thermonuclear" and "reactor" on public perception. Food irradiation is an example of a perfectly safe technology that has nonetheless generated a strongly negative public response because the public relations and education were insufficient.

In the regulatory arena, the group argued that it is essential that fusion look and act differently from fission. Otherwise, regulations covering fission reactors will be applied to fusion. Changing these regulations to fusion-specific rules would be extremely difficult once they have been put in place.

The direction for fusion research in this area should be to take control of the regulatory agenda. In principle, regulations are laws that should be technology driven and not set by precedence. Comparisons with nuclear plants should be kept to a minimum because the demonstration that fusion plants can meet fission regulations presumes and encourages that fission rules apply to fusion. It should be argued that fusion needs separate and distinct rules and regulations appropriate to it (some nuclear rules may apply to fusion such as waste disposal regulations). Again, the view is that fusion should take charge of this agenda and start a program to define the scope of regulations needed for fusion power plants. This urgency is underlined by the program's plans for the ITER device.

Fusion Demo

While the requirements for a Fusion Demo were not discussed at great length, the participants strongly noted that a DEMO plant should be built based upon and using the same technology as will be used in commercial units so that no questions remains regarding scaling to a commercial plant. Therefore, the predecessors to a DEMO must demonstrate these technologies (i.e., fusion should start research in the technologies required for fusion reactors immediately). As a whole, the sentiments of the participants regarding the requirements for the Fusion Demo are similar to the sentiments expressed by a previous panel formed during the ARIES study [1]. The requirements for the Fusion Demo and for development pathways will be discussed in detail at the next meeting of the Utility Advisory Committee.

FOLLOW UP BY THE ARIES TEAM

(1) The ARIES Team will review the regulations concerning the need for an emergency evacuation plan and will aim to determine if fusion plants will be exempt.

(2) An activity to review the regulations covering fission reactors will be started with the aim of providing a preliminary assessment of which, if any, regulations apply to fusion.

Because of the limited time available, a major discussion of issues related to operation and design of the fusion plants were left to the next meeting.

The following items are noted and were in response to questions raised about power plant design.

(3) It is important to the utility to know if partial power operation of the plant is feasible and if the plant can follow the load. (A turn-down power ratio of 1/3 would be perceived as a very important feature of the power plant, according to those present.)

(4) While there is no general objection to a fusion plant with a pulsed plasma burner (as long as the electricity output is steady), the Committee felt that much work would be needed to convince power companies that such a plant would be reliable. The necessity for energy storage to ensure continuous electrical power output appears to be an inherent weakness of the concept. There was concern about degradation of components in the tokamak and elsewhere as a result of pulsing, e.g., in power supplies, breakers, switches, butterfly valves to control the energy storage medium, and so on. The ARIES Team will itemize these components, examine the available data base, look at the implications for maintenance and reliability, and design to eliminate single point failures.

(5) The ARIES Team will provide a total plant diagram that highlights the differences (such as tritium systems) between a fusion plant and other plants (such as nuclear plants).

REFERENCE

[1] R.W. Conn, F. Najmabadi, S. Sharafat, R.A. Krakowski, and K. A. Schultz, "The Requirements of a Fusion Demonstration Reactor," UCLA report UCLA-PPG-1394 (1992).