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\begin{document}

\title{\bf 2. REQUIREMENTS AND GOALS FOR COMMERCIAL AND
DEMONSTRATION FUSION POWER PLANTS}
\author{
\autlist{Farrokh Najmabadi}{Lester~M.~Waganer}{Mark~S.~Tillack}
}
\date{ }
\maketitle

\begin{titlepage}
{%\baselineskip=1.8ex
\tableofcontents
}
\end{titlepage}

\setcounter{chapter}{1}
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\chapter[REQUIREMENTS AND GOALS FOR FUSION]{REQUIREMENTS AND GOALS FOR
COMMERCIAL AND DEMONSTRATION FUSION POWER PLANTS}

\section{INTRODUCTION}
\label{s-2-1}

The demand for substantial increases in electrical power requirements has been
forecast for decades. Conservation and use of relatively inexpensive fuel have
reduced the need to develop new electrical energy sources, affording more time
for the development of new sources of energy.  At the same time, environmental
concerns have severely curtailed many of the previously viable electrical
sources. Improved power plants using existing energy sources are meeting with
increasingly difficult regulations to continually improve both local and global
environmental impacts. Fusion offers the promise of an abundant energy source
that is not tied to national resources and will have only a minimal impact on
the environment. As such, there exists a window of opportunity to become a
substantial provider of electric power.

During the past decade, enormous progress has been made toward demonstrating
the necessary physics and engineering goals in experiments such as DIII-D,
TFTR, JET, and JT-60. The proposed ITER device will continue to advance the
state of knowledge toward a clearer understanding of the creation, control, and
use of large-size tokamak plasmas. The last step in the development of fusion
is a demonstration power plant which is built and operated to assure the user
community that fusion is ready to enter the commercial arena of electrical
power generation.

Paramount to a project such as the U.S.\ Fusion Demo is understanding the
customer needs. From that, one can derive a qualitative mission statement which
describes the intent and purpose of the project and how it addresses customer
needs, and the requirements which translate the customer needs into
quantitative measures. Based on experience and the existing data base,
conceptual designs are then developed and used to refine the requirements, as
well as to identify critical issues and R\&D needs. An R\&D implementation plan
is then produced and implemented. This concept development phase may be
repeated as further conceptual designs are developed, based on the new data and
new R\&D, until sufficient confidence is achieved to proceed with the
preliminary design phase of the project.

In this context, the Starlite project was commissioned to initiate the process
by investigating the mission, requirements and goals, features, and key R\&D
requirements of an electricity-generating, fusion demonstration power
plant. The project includes broad participation from several organizations in
the U.S.\ engaged in fusion research, including universities, national
laboratories and industrial partners. A fully integrated approach to power
plant analysis and design was adopted. A set of criteria for fusion power has
been derived based on interaction and advice from the utilities and
industry. These criteria were then used to develop a mission statement as well
as top-level system requirements for the commercial and demonstration fusion
power plants. This work is reported in this section. Several candidate options
for the physics operating regime as well as the engineering design of various
components ({\it e.g.,} choice of structural material, coolant, breeder) have
been developed and assessed against the top-level system requirements and
reported in the remaining sections of this report.

\section{REQUIREMENTS \& GOALS FOR FUSION POWER }
\label{s-2-2}

A demonstration power plant will be built and operated in order to assure the
user community (the general public, utilities, and industry) that fusion is
ready to enter the commercial arena of electrical power generation. Thus, the
requirements and goals for acceptance of fusion power must first be defined.

Power producers (utilities and independent power producers) and the industries
that manufacture the power plants demand that any source of energy will be a
commercial success ({\it i.e.,} affordable, profitable, and meeting public
acceptance). The general public and government agencies ask for an energy
source which is safer, generates little or no waste, does not deplete limited
natural resources, and has minimal effect on the environment. These are common
goals shared by all other existing and alternative energy sources. Fusion
power, therefore, should meet these goals.

Fusion power in its present embodiments will result in a large, central-station
power plant. At present, the investor-owned, public electric utilities best
represent the customers for this type of power plant. To better understand the
needs of this class of customer, the Starlite Project solicited several large
public utilities and support industries to help define the requirements and
goals for fusion power. Several utilities and industries agreed to help
establish and participate in a Power Plant Studies Utility Advisory
Committee. This committee provided advice to help formulate the mission and
goals for fusion in general, and for a fusion demonstration power plant in
particular. The case for an attractive fusion power was developed, as shown in
\hbox{Table~\ref{t-2-2-1}} and discussed below (A similar set of criteria has been developed by the EPRI fusion working
group~\cite{Kas94}):

\begin{table}[b]
\caption{}
\centering{\bf Elements of the Case for an Attractive Fusion Electric Power
Source}
\vspace{1.0cm}
\renewcommand{\arraystretch} {1.3}
\begin{tabular}{r l }\hline
\hline \\
 1. & Cost advantage over other available central station options \\
 2. & Eased licensing process \\
 3. & No evacuation plan needed \\
 4. & No high-level waste produced \\
 5. & Reliable, available, and stable electrical power production \\
 6. & No local or global atmospheric impact \\
 7. & Closed on-site fuel cycle \\
 8. & High fuel availability \\
 9. & Plant capability of load-following \\
10. & Availability in a range of unit sizes \\
\\ \hline
\end{tabular}
\label{t-2-2-1}
\end{table}

\paragraph{Cost advantage over other available central station options.}

Because fusion is a new technology in the energy marketplace, it must have a
cost advantage to offset the inherent technical risk of a new technology;
otherwise, it will never be widely endorsed. It should be noted that this cost
reflects a complete life-cycle cost; that is, it includes costs associated with
decommissioning, waste-disposal, costs due to delays in licensing and/or public
opposition to an evacuation plan, {\it etc.} Fusion should achieve its full
safety and environmental potential for it to have a cost advantage over other
sources of electricity.

\paragraph{Eased licensing process.}

To circumvent the difficulties experienced by fission, fusion should be easy to
license by the national and local regulating agencies. Only through the use of
low-activation materials and failure-tolerant design will fusion power plants
be designed such that the consequences of an accident are minimal.

\paragraph{No evacuation plan needed.}

In order to gain public acceptance and support, fusion should demonstrate that
it does not disturb the day-to-day life of the public. Fusion must be perceived
by the public to be inherently safe. To support this criterion, fusion power
plants should not require a site evacuation plan.

\paragraph{No high-level waste produced.}

An important public demand is that new technologies not provide a burden for
future generations; that is, waste generated should be either recyclable or
disposable in a time frame which is within a human life span. Therefore, to
gain public acceptance, fusion should not produce long-lived high-level waste.

\paragraph{Reliable, available, and stable electrical power production.}

Because fusion is a new technology, it must demonstrate that it can achieve the
necessary degree of reliability. This criterion should be addressed early in
the development path of fusion power. Todays experiments are, by their
charter, experimental devices and are not intended to provide detailed
engineering data to support the design, construction, and operation of a power
plant. Experiments with burning plasmas will provide some data, but
the design and construction cycle of these devices are so long that data can be
obsolete by the time they are obtained. This set of requirements is perceived
as the most difficult to achieve in a time-constrained development program.

The remaining criteria are foreseen as reasonably easy for fusion to achieve
but are significant attributes for an electrical power source. The desire for
no atmospheric impact is a powerful requirement in light of the difficulties of
competing energy sources. No scrubbers, containment buildings, or special
active safety systems will be needed in fusion plants.  The self-contained fuel
located on site is a powerful advantage that circumvents strikes, natural
calamities, and adverse supplier actions. This helps the utility better control
their self destiny. Fuel availability is similar in that all elements in the
fuel cycle are in abundant supply with no critical resource shortages. The last
two criteria deal with how well the fusion plant will function in conjunction
with the power network and the time-varying energy demand. There appears to be
no difficulty in designing a fusion plant to load-follow ({\it i.e.,} operate
at a fraction of their full power rating). Availability in a range of sizes is
limited only by the fact that smaller sizes would tend to be more costly on a
COE basis.

If there were reasonable assurances that this set of high level criteria could
be met by a demonstration power plant, then the decision to purchase a
commercial fusion electrical power plant would likely be positive. Thus the
intent for the Demo power plant is to use these criteria as guiding features to
help structure its mission and goals.

\section{MISSION \& REQUIREMENTS FOR THE FUSION DEMO}
\label{s-2-3}

The prior section discussed the goals needed for the commercial plant to be
accepted and to succeed. On the other hand, the Demo must ``demonstrate'' those
attributes that would convince the utility or their investors and the public
that this new technology, for long periods of time, is safe, economical, and
does not harm the environment. The Demo need not meet 100\% of all commercial
power plant goal objectives, but the risk in eventually meeting those goals in
a power plant must be acceptable. The public is very concerned about safety and
environmental impact; thus this goal must be demonstrated to a high level of
confidence, {\it i.e.,} low risk. The economics goal (for the Demo) would be
difficult to meet without significant government or investor subsidies to
artificially lower the capital and operating cost. Thus the owner/operator of
this demonstration power plant must be able to operate the plant on the power
grid for long periods of time and gain both operational experience and profit
for the sale of electricity. The public perception of the interaction of the
first fusion power plant with the environment will be a highly visible public
issue. This is another area where the Demo plant must convincingly demonstrate
over long time periods that fusion is a ``good neighbor.'' There will have to
be high visibility of all safety and environmental issues to comfort and
sustain the public.

Based on the above arguments, the Starlite project has adopted the following
mission statement for the U.S. Fusion Demo Power Plant:

{\it The Fusion Demo demonstrates that fusion power is a secure, safe,
licensable, and environmentally attractive power source that is ready for
commercialization at an economically superior total cost.}

This mission statement is supported by the demonstration of a set of
qualitative attributes. These attributes include:

\begin{enumerate}

\item
{\bf Technology and Performance Demonstration:} Demo should use the same
technologies as planned for commercial power plants. Introduction of a new
technology ({\it e.g.,} different plasma operating regime, coolant, or
structural material) would be inappropriate, as this would require that a new
development path be initiated.

\item
{\bf Integration and Scalability Demonstration:} Demo should demonstrate all
systems working as an integrated unit.  The Demo should be large enough so that
the step to the first commercial power plant is small.

\item
{\bf Economics Demonstration:} Initiation of the Demo construction requires
clear demonstration that the successful operation of the Demo will lead to a
economically superior power plant. Operation of the Demo should demonstrate
that construction, operation, maintenance, and decommissioning costs are in the
forecasted range, and that the power plant would have a competitive life-cycle
cost of energy.

\item
{\bf Safety and Licensing Demonstration:} Demo should demonstrate that fusion
power is safe. Demo should conduct demonstration testing, as an element of
certification by regulatory agencies, which enhances public acceptance and will
support timely licensing. Demo should provide the data base necessary to obtain
certification by the regulatory agency of the standard plant in order to ensure
timely licensing for commercial plants and instill investor confidence.

\item
{\bf Waste-Disposal Demonstration:} Demo should demonstrate that fusion
generates only low-level waste and all waste can be recycled and/or disposed of
at an acceptable cost.

\item
{\bf Decommissioning Demonstration:} Demo should demonstrate that
decommissioning can be performed at an acceptable cost.

\item
{\bf Reliability Demonstration:} Demo should demonstrate that fusion power
plants can operate within the prescribed performance envelope (load following,
start-up and shutdowns, load ramp rates, endurance operation) with unscheduled
internal events not exceeding the designed and prescribed values.

\item
{\bf Maintainability Demonstration:} Demo should demonstrate that fusion power
plants can be maintained (both scheduled and unscheduled maintenance) within
the prescribed cost/schedule envelope. This is necessary to both achieve the
desired availability and eliminate the risk of a plant write-off because of a
severe internal accident.

\item
{\bf Availability Demonstration:} Demo should demonstrate that fusion power
plants meet or exceed availability targets that are competitive with other
sources of electric energy.

\item
{\bf Operability Demonstration:} Demo should demonstrate ease of
operation. Demo should demonstrate that routine emissions from the plant are
all below allowable values.

\item
{\bf Industrial Supplier Demonstration:} Demo should stimulate an industrial
infrastructure which is prepared to supply fusion power plants on order. Demo
should yield the industrial commitment to deploy the first series of commercial
power plants.

\item
{\bf Power-Producer Interface Demonstration:} Demo should stimulate
establishment of a power producer (user) interface which is prepared to provide
operational support programs and support generic regulatory interactions in
order to ensure timely penetration of fusion power plants into the market.

\end{enumerate}

\section{TOP-LEVEL REQUIREMENTS}
\label{s-2-5}

The list of attributes, discussed in previous sections, must be quantified in
order to formulate a Demo program and eventually define a credible conceptual
Demo design which would lead to a commercially acceptable, electric generation
plant. To quantify the goals or attributes supporting the Demo Mission
Statement, the Starlite project defined a set of top level requirements for
both the Demo and the commercial power plant, shown in
\hbox{Table~\ref{t-2-5-1}}. Each of these requirements will be discussed as to
background and implications for meeting the requirements.

\begin{sidewaystable}
\caption{}
\centering{Top-Level Requirements and Goals \\ }
\centering{for Commercial and Demonstration Fusion Power Plants}
\vspace{1.0cm}
\renewcommand{\arraystretch}{1.3}
\begin{tabular}{l c c }\hline
Element			                  & Demo  & Commercial \\
\hline 
					  & \hspace{1.4in} & \hspace{1.4in} \\
Must use technologies 
to be employed in commercial power plant  &  Yes             & Yes \\

Net electric output must be greater than  & 75\% commercial  & N/A \\

Cost of electricity (COE)
must be competitive (in 1992 mill/kWh)    & 80 (Goal)        & 65 (Goal)  \\
                                          & 90 (Reqmt)       & 80 (Reqmt) \\
No evacuation plan
required for any credible accident:  \\
\quad Total dose at site boundary         & $< 1$~rem   & $< 1$~rem \\

Generate no rad-waste greater than        & Class C          & Class C \\
                
Must demonstrate public
day-to-day activity is not disturbed      &  Yes             & Yes \\
                
Must not expose workers
to a higher risk than other power plants  &  Yes             & Yes \\
                
Must demonstrate robotic
maintenance of power core                 &  Yes             & Yes \\
                
Must demonstrate routine
operation with less than \\
\quad (x) unscheduled shutdowns per year including disruptions &   1              & 1/10 \\

Demonstrate a closed tritium fuel cycle   &  Yes             & Yes \\
                
Must demonstrate operation
at partial load conditions at             & 50\%             & 50\% \\

\\ \hline
\end{tabular}
\label{t-2-5-1}
\end{sidewaystable}

\paragraph{Commercially-relevant technologies.}

The U.S.\ Demo must use and demonstrate the same technologies that will be
incorporated in a fully-commercial power plant. This requirement is fundamental
in determining the features of the Demo and may or may not be adopted by other
countries in their definition of a ``Demo.'' If the basic technologies are
changed following the Demo, then another Demo must be built before the design
and construction of the commercial plant. A private investor will not accept
risk of failure or reduced performance due to unproven and undemonstrated
technologies. Additionally, it may be impossible to insure and/or license such
a plant.

This requirement allows for the performance levels to be reduced from a fully
commercial plant as specified in the remaining Demo requirements. For example,
a reduced level of thermal efficiency, availability and component lifetime in
the Demo (owing to less competitive cost of electricity) allows the components
to be designed slightly different and operate at lower temperatures and
stresses. There is no requirement that specifies the component operating
conditions must be exactly prototypical.

However, through operation of the Demo, a high level of confidence must be
gained so that the first commercial plant is assured to meet the more stringent
commercial power plant requirements. If performance levels are reduced from
that of a full commercial plant, then the ability to extrapolate must be
clearly demonstrated. The method to demonstrate this extrapolation has not been
specified.

\paragraph{No evacuation plan.}

One of the most powerful advantages that fusion may possess is that the risk to
the public may be low enough so as to not require an evacuation plan for the
surrounding population. In discussions with the utilities, much time and effort
are devoted to prepare for and obtain acceptance of the evacuation plans. If
there were no need for an evacuation plan, the siting of the plant would be
much eased and the licensing could be expedited.

Careful control of vulnerable tritium inventories should allow attainment of
this goal of 1~rem total dose at the site boundary. Choice of power core
materials and coolants will be tailored to eliminate or limit generation or
transport of hazardous material to the site boundary. This will minimize the
accident potential or consequence.

\paragraph{No radioactive waste greater than Class C.}

The requirement to generate no radioactive waste greater than Class C was
levied on the Demo plant because there is a general public aversion to creating
hazards that need protection for long periods of time. The governmental
regulators are responding to the public concern by increasingly stiffening
applicable legislation. Fusion power plants could be constructed and operated
with a number of materials that could meet the physical design
properties. However, it was anticipated that plants that generate high-level
radioactive waste, even at small amounts, might result in an adverse public
reaction. Power plants, both public and private, are highly visible by the
general public and environmental groups. Thus to be prudent, Starlite adopted
the requirement that all generated waste must meet the requirement to be Class
C or better.

This stringent requirement requires that the in-vessel materials generally be
made of low-activation materials. This would suggest vanadium, ferritic steel,
or silicon carbide as the structural material. The composition of these
materials would be tailored to eliminate or reduce offending trace elements
that would contribute to high level radioactivity. There are still open
questions as to the use of mixed waste, the degree of isotopic tailoring
required, and the cost of meeting these requirements.

\paragraph{Public day-to-day activities not disturbed.}

The requirement to demonstrate the public day-to-day activities should not
be disturbed arose from the desire to have public acceptance of
fusion. Utilities spend a great deal of time and money assuring the public that
they will not be disturbed. There are many public hearings discussing the
intrusion of electrical generating plants into their communities. Fusion has
long professed that it was a safe energy option and now it must demonstrate
that indeed it is.

This requirement is foreseen to be a combination of many factors to assure the
public that the fusion power plant will not intrude into their lives (except
through the wall outlet). The requirement for no evacuation plan is an integral
part of the plan. They can be assured that regardless of what happens at the
plant, they will never have to be evacuated from their homes. The requirement
for no high level radioactive waste assures that they will never worry about
transportation of that waste through their highways, rivers, or rail lines. The
on-site, closed fuel cycle minimizes the traffic of fuel suppliers.

\paragraph{Not expose workers to a higher risk than other power plants.}

Protection of the plant worker is also a strong incentive to provide
safeguards. All work environments entail additional risks over and
above that for non-work environments. Fission plants have adopted design
approaches and strong requirements to safeguard their employees from nuclear
materials. Other forms of electrical power generation plants provide stringent
worker safety related programs.

From the start, fusion should be mindful of the plant worker safety. It is a
nuclear process with radioactive components.  In all activities involving
radioactive components or dangerous situations, robotic or remote maintenance
should be incorporated. Particular attention is required for tritium handling
and containment. High pressure or liquid metal coolants will require special
hardware and procedures.

\paragraph{Closed fuel cycle.}

Tritium is not available naturally, therefore an important Demo requirement is
to demonstrate that a power plant will never be at risk of running out of
fuel. Since there are no secure external sources of tritium, loss of the
on-site tritium inventory could lead to a serious crisis for the utility,
making it impossible to operate the plant.  During long down-times, on-site
tritium will decay (12.4~y half-life). Thus, maintenance of adequate reserves
to survive extended down-times is mandatory. In an economy with multiple fusion
plants on-line, the guarantee for reserves is reduced somewhat, since an
operating plant could provide start-up inventory for a plant coming on line.

The power level and availability goals of Demo are such that Demo itself could
not operate without a closed fuel cycle.  At 3000~MWe and 80\% availability,
250~g of tritium would be consumed daily. The expected supply of tritium from
external sources (such as CANDU reactors) for Demo will be only a few
kilograms, and even this may be absorbed by test facilities such as ITER. In
that case, the demonstration of a closed fuel cycle is mandatory if Demo itself
meets its other requirements.

The utilities have not specified any requirements on Demo to over-produce
tritium, although this may be an important goal in order to provide the initial
start-up inventory needed for the first generation of commercial plants. In any
case, even small excess tritium production rates in Demo will provide more than
adequate start-up inventories (estimated at a few kilograms), such that this is
not expected to create any additional design considerations.

Aside from the uniqueness of tritium, it is a powerful advantage for a utility
to have the autonomy of possessing all the fuel on-site for the lifetime of the
plant. There can be no pressure from suppliers or natural disasters to impede
the availability of the fuel supply. This feature also allows the utility to
determine up front the fuel cycle costs and not be subject to the whims of the
external marketplace.

\paragraph{Net electric output greater than 75\% of commercial.}

The requirement for the demonstration plant to generate electricity at a
capacity near to that anticipated for the commercial plant is determined by
economics and the perceived risk to scale to a full-sized plant. The premise is
that Demo is to be built and operated by a utility. This plant is to be
designed to be fully integrated into a power grid for the purpose of power
generation. Thus it must of a size sufficient to contribute to the grid demands
and be profitable. The present understanding of tokamak fusion power plants is
that below a net capacity of several hundred megawatts, the plants have very
unfavorable economics. Even with a moderate size and other less optimal
performance parameters such as reduced availability, substantial financial
subsidies will be required for a nominal rate of return for the Demo.

The second factor is technical risk to scale to a full-sized plant from a much
smaller demonstration plant. If the demo is too small, it entails too high a
risk for the investor. On the other hand, building the Demo too large puts a
larger burden of risk on Demo, extrapolating from the database of the then
existing experimental devices. ITER may have the proper size plasma, but other
subsystems may not be of an adequate size to serve as the design basis for
Demo.

Within the fusion community and the Utility Advisory Committee, the debate
continues regarding the proper size for a commercial plant. One faction would
prefer a small plant that could be sited anywhere there is a demand, basically
in a distributed network. Another view is that large power parks should be used
as bigger is better. The latter view is better suited to the nature of tokamak
power plants, but it is not a convincing argument. In formulating its Demo
requirements, we chose that the Demo be roughly 75\% of the size of the
commercial plant. This would provide adequate size for the economics to be
viable and also have acceptable risk in scaling the relevant technologies.
Ultimately the Demo size will be chosen based on market economics at the time
of the Demo project.

\paragraph{Operation at partial load conditions.}

The operation of a power plant at partial load condition is a reasonable
expectation for any plant that is to be integrated into a power grid with a
minimum of difficulties. The only question is the lower level of operation at
which it is expected to operate continuously. The Utility Advisory Group
thought that 50\% would be a reasonable value for a base-loaded plant. If it
were to be load-following, which it is not, then it would have to operate at a
much lower capacity. It is not foreseen that tokamak reactors would have any
inherent problems with operation at reduced capacity. As with any base-loaded
plant, the economics are not favorable at reduced capacity operation.

\paragraph{Maintainability.}

It is not foreseen that a fusion power plant will allow hand-on maintenance
following operation with DT fuel. Therefore, the ability to remotely remove and
replace any component which can fail must be demonstrated, even if the
component does not actually fail during operation. It is anticipated that the
majority of fusion power plant maintenance will be done by robots, such that
all robotic systems must be demonstrated during Demo operations. Further,
robotic maintenance is meant to be predominantly computer controlled
maintenance with minimal human intervention except for key actions or unique
situations. This will allow faster and more reliable maintenance operations for
known and repetitive operations.

It is likely that these maintenance demonstrations would be performed prior to
the start of DT operation, such that any flaws or failures may be corrected
prior to activation. A high degree of confidence in the repair time is
necessary in order to meet the very high availability goal of Demo.  The
availability goal of Demo is stated in such a way that initial operations need
not meet the full availability goal. This allows for some tolerance for
extended down-times due to maintenance. However, given that Demo is expected to
be constructed with some fraction of private investment, there will be very
strong economic incentives to minimize downtime during any phase of operation.

Demonstration of maintenance actions encompassing plant operations to the
end-of-life of in-vessel components also will be essential. Changes in material
properties, permanent deformations, and chemical and physical interactions may
complicate maintenance procedures. End-of-life maintenance demonstration will
occur naturally because the total operating life of Demo is expected to exceed
the lifetime of a set of in-vessel components. A utility will demand positive
results from the demonstration and replacement of components prior
to committing to the construction of the first commercial plant.

\paragraph{Unscheduled shutdowns.}

Unscheduled shutdowns are very undesirable for a power plant operator. Besides
the obvious impact on availability resulting from down-time, a power plant
cannot be brought back on-line immediately following an unplanned outage until
the source of the problem is identified, any damage is repaired, and corrective
actions are taken to prevent future occurrences.

A major plasma disruption is one such intolerable event. The requirement to
avoid disruptions is difficult to achieve and may require performance
trade-offs in order to operate the plasma far enough from any stability
boundaries that the frequency of disruptions is reduced below one per year
[4]. Note that the unscheduled shutdown requirement is one per year total for
all systems and should include in-vessel component premature failure, power
conversion systems, fueling systems, {\it etc.} Surprisingly, the consequences
to the surrounding structures may become a secondary concern since these can be
repaired and replaced relatively quickly, while the ability to determine the
source of a disruption and correct the flaw may require substantially more
time.

\paragraph{Cost of Electricity.}

The final requirement is that the cost of electricity (COE) for the Demo must
establish the economic competitiveness of fusion. An actual value for
this requirement was difficult to quantify but the Starlite project felt the
general fusion community needed guidance in this area. In response to that
need, both a goal and an upper limit requirement were established for the Demo
and the commercial power plant. While long-range electrical demand projections
are uncertain and the target for a competitive COE is elusive, costs are an
important design consideration. It was felt that if the COE of 65~mills/kWh
were obtained, fusion energy would likely be seen as a formidable competitor.
Realists sought some relief from the seemingly difficult demand to reach such a
value. Thus the commercial goal was provisionally set at 65~mill/kWh and the
upper limit requirement was established at 80~mill/kWh. Rollback to the Demo
requirements resulted in adoption of a COE goal of 80~mill/kWh and a
requirement of 90~mill/kWh.

To achieve the bottom line COE values, all the elements in the cost of
electricity must be determined and controlled.  Resolved into capital and
operating cost components, the COE projection is driven by decisions regarding
plant size (noting economies of scale), materials choices [6], thermal cycle
efficiency, availability, and maintenance scheme as well as a host of other
factors. There is a strong incentive to expedite the construction time to lower
the finance costs.  Plant availability is determined by the interplay between
design margins and redundancy, which affect the forced outage rate. Access and
modularization of the power core influence the mean time to repair, scheduled
outage durations, and capital cost. These sub-tier requirements will be
initially allocated to arrive at an overall acceptable COE. As the design
evolves, trade studies will continue to determine the best mix of risk,
performance, and cost.

Since the Demo will still be on a steep part of the performance and cost
learning curve, it will not represent an optimal design for a commercial
plant. Moreover, it would still have to carry the burden of some development
costs, increased costs associated with first-of-a-kind production components,
and higher contingency allowances. Thus Demo would not be expected to achieve
the desired COE values without significant government or investor subsidy to
artificially lower the capital and operating costs. Thus the owner/operator of
this demonstration power plant must be able to operate this demo plant on the
power grid for long periods of time and gain both operational experience and
profit for the sale of electricity.

\section{SUMARY AND CONCLUSIONS}
\label{s-2-6}

This set of requirements constitutes the Starlite project guiding principles to
arrive at a commercially acceptable electric-generating power plant. This is
the ``market pull'' portion of the equation. On the other side of the coin is
the ``technology push.'' The size and power level of tokamak plasmas are
reaching the size necessary for commercial applications. The control and
stability of the plasmas are sufficient for experiments, but need to be
demonstrated for commercial usage. The current drive systems for long duration,
steady-state plasma need to be applied to large tokamak plasmas. Low-activation
materials for the power core structure and shielding need to be developed,
validated, and applied in components operating in representative high heat and
radiation environments. Much work remains to establish the solid technology and
engineering foundations upon which the Demo can be designed, built, and
operated. Hopefully, these top level requirements will provide insight for the
program to help achieve a successful commercial venture.

\clearpage


\begin{thebibliography}{99}

\bibitem{Kas94} J.~Kaslow \ea, ``Criteria for Practical Fusion Power
Systems - Report from the EPRI Fusion Panel,'' EPRI report BR-104469 (1994).

\end{thebibliography}

\end{document}