Innovation in Global Power - Parsons Brinckerhoff

Thermal – Achieving New Efficiencies, Reducing Carbon Emissions
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that a suitably qualified shut-off valve and additional bypass
valves would be needed to limit the potential impact of any
downstream failure in the NuGas TM cycle.
Installation risks are minimized. The interconnection
design minimizes installation risks and ensures that the main
plant is unaffected by maintenance of the NuGas TM plant and
that CCGT operation can continue independently of reactor
operation. This is fundamental, as significant costs would be
charged by the grid operator for increasing the loss of generation
resulting from a single fault. In addition, the project
economics would be adversely affected if the availability of
either plant was to be degraded by the linking of the cycles.
Safety case is maintained. NuGas TM raises overall efficiency
by enhancing the thermodynamic cycle rather than changing
operating conditions, so in addition to being inexpensive, it
introduces no new technology risks in its implementation.
The plant design incorporates additional systems to control
high temperature steam flows linking the nuclear and CCGT
units, ensuring that the integrity of the nuclear safety case is
maintained.
To ensure that all the additional hazards associated with the
introduction of the CCGT are assessed, a full HAZOP has
been carried out to ensure that risks are well within the
currently assessed fault scenarios.
New Build
Currently, the two leading candidate PWR designs for new
nuclear construction are the Evolutionary Pressurized Water
Reactor (EPR) from AREVA with a nominal power rating of
1600 MWe and the Westinghouse AP1000 reactor with an
output of around 1140 MWe. Either the EPR or AP1000
could be integrated with a NuGas TM cycle to offer extra
capacity with the highest possible efficiency for fossil fuel
conversion without significantly increasing the loss of output
in the event of a reactor trip.
If the NuGas TM concept was applied to an AP1000 with a
nuclear plant electrical output of 1140 MW, the combined
plant would have an output of approximately 1470 MW for an
additional capital cost of around $250 million ($800 to $1000
per incremental kW). The cost of the NuGas TM integration is
approximately $50 million, which can be considered to offer
additional capacity with no additional fuel burn. Pessimistically
at a fuel price of $7/MMBTU, a cost that is conservatively
below current levels and below recent longer term forecasts,
the investment to combine the plants would have a typical
payback time of less than three years. At higher gas prices,
the benefits are increased and the payback period
correspondingly reduced.
Backfit
The renaissance of interest in new nuclear power plants will
mean that by 2015 and beyond more nuclear plants will be
brought on-line, but for the next seven years utilities waiting
for their new nuclear plants to be licensed and built may be
faced with a generating capacity gap. Some utilities are,
therefore, considering building interim plants with a low capital
cost and rapid construction times, characteristics of the
CCGT. Building a CCGT and combining it with an existing
nuclear power plant can provide a rapid method for increasing
power generation capacity with exceptionally high thermal
efficiency, making it far more profitable than stand-alone
CCGTs. The necessary connections to the nuclear steam
cycle can be readily made during the refuelling outages on
the nuclear plant, thereby minimizing disruption and cost.
A further key advantage for the NuGas TM concept arises
where the nuclear plant has increased operating margins
such that more heat can be emitted by the reactor. In some
cases this extra output cannot be converted to electricity
as the existing steam system cannot operate at significantly
higher rates. Because the NuGas TM cycle increases steam
utilization capability by at least 10 percent, it can use excess
steam without expenditure or shutdowns for costly steam
cycle upgrades, making the NuGas TM conversion even more
attractive financially.
Conclusion
By re-examining power generation options and focusing on
improving efficiency to reduce carbon emissions, it has been
possible to developing a novel concept that brings together
the best aspects of nuclear and gas-fired power generating
technologies. The concept is now being developed with
utilities and plant vendors, with a target of going into service
before 2013.
Paul Willson, Deputy Director of Engineering, Generation within PB’s power and energy business in Manchester, has worked for PB and its predecessors for more than 25
years. He leads the Development and Emerging Technology Group, which is responsible for independent power and water project development and for innovations. Paul
is co-inventor of the NuGas technology.
Alistair Smith, Director of Nuclear Services for PB based in Manchester, has worked in the nuclear power industry for 27 years and has worked on all phases of the
nuclear plant lifecycle covering design, construction, operation and decommissioning. He is the chairman of the UK Institution of Mechanical Engineers Nuclear Power
Committee, chairman of the Nuclear Industry Association’s industrial group, and is a spokesman for the UK nuclear industry.
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