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September 07, 2008

Annular fuel 50% power ultra-uprate to nuclear power - Economics versus new nuclear plants is the key issue




MIT and Westinghouse have been working on increasing the power of existing pressure water nuclear reactors by 50%. A test reactor at MIT had successful tests. The technical and economic issues continue to be studied. This presents the economic and technical analysis that are being performed. In 2006, Korea Atomic Energy Research Institute started a project for development of PWR annular fuel. The ultra uprate makes economic sense where there is a lot of extra generator capacity at the plant and in the surrounding electrical grid. A half ultra uprate 25% makes economic sense in more places. 7-50% uprates can be performed depending upon the economics at each location and the capacity situation at each location. Use varying levels of ultra-uprate to max out the generator and other capacity. Plus other aspects of new plant construction or licensing could make ultra-uprates more attractive and incremental upgrade/replacement of fuel rods with annular cylinders should improve the economics.



The cost evaluation indicates that the largest cost components are the
replacement of power (during the outage required for the uprate) and the new
fuel loading. The preferred option for the BOP uprate (to build a new
Turbine/Generator building for the added power) has a large negative impact in
the economic aspects of the uprate. In particular, the cost per installed kilowatt of
the added components will be relatively large due to the relatively poor economy
of scale (25 to 50% of total). Based on these results, the study concludes, in
Section 10, that for a “standard” 4-loop plant, the proposed Power Ultra-Uprate is
technically feasible. However, the power uprate is likely to be more expensive
than the cost (per Kw electric installed) of a new plant when the large capacity
uprate is considered (50%). Nevertheless, the concept of the Power Ultra-Uprate
may be an attractive option for specific nuclear power plants where a large
margin exists in the steam and power conversion system (BOP). The conclusions
of the study suggest that development efforts on fuel technologies for current
nuclear power plants should be oriented towards improving the fuel performance
(FW, corrosion, uranium load, manufacturing, safety) required to achieve higher
burnup rather than focusing on potential increases in the fuel thermal output.




A [255 page] 2006 assessment of ultra uprate economics.

Market data suggests that in order to make the ultra-power uprate financially attractive to the utility, its cost has to be kept within the range of the following industry reference costs:
NOTE: New plant construction and all power generation costs are now higher, which changes the economic assessment.

• $1200-$2200/kWe for new plant construction
• $600/kWe for Upgrade programs
• $600-$800/kWe for gas fired combined cycle plants

The study concluded that:
• Power Ultra-Uprate 25%: Acceptable DNB (Departure from Nucleate Boiling) margins were obtained without replacing the pumps by increasing ΔT and lowering Thot
• Power Ultra-Uprate 50%: Sufficient DNB margin is obtained only if RCPs
are replaced and pump power is doubled

So where costs are in the $2000-6000/kWe for new plant construction increases the places where ultra uprates work economically. There are many places where medium uprates (25%) work and the 50% uprate work [economically, technical feasibility works everywhere] .


Early candidate plants



Cost estimates

Improvement in the uprate unique costs by the deduction of already replaced steam generator costs and reduction in the outage length, if they have been already replaced due to corrosion or equipment aging replacements, would further shrink the cost differential.

A positive factor for the Ultra Uprate which does not show up in the simple cost
comparison is an expected shorter construction time for the uprate compared to
licensing and construction of a new plant on a new site. This could be especially
important for plants that have capacity shortages and expect rapid demand
growth.


Safety and economic presentation.

Loss of Coolant Accident (LOCA)
- A RELAP5/MOD3.2 large LOCA model of 4-loop Westinghouse
plant was developed to handle both the different geometry and
the higher power components.
- LOCA analyses performed for 100% and 150% power.

Loss of Flow Accident and Main Steam Line Break
(LOFA and MSLB)
- A RELAP5 model for MSLB and analyzed 100% and 150% case.
- A RELAP5/MOD3.2 model for LOFA and performed analyses at
100% and 150% in conjunction with VIPRE-01.

Increase dimensions (inner hole 8.6 mm, outer clad 15.4 mm)
will maintain hydraulic diameter

Annular fuel allows PWR power density to be raised by 50% within current safety limits The sintered fuel pellets appear viable with appropriate manufacturing- need lead tests Uprating is economic, depending on plant
remaining lifetime, with IRR from 20 to 27%

A Mixed Transition Core...
- yields comparable MDNBR to reference core.
- yields comparable pressure drop to reference core.
- may be allowed to raise core power by 7.5%.


FURTHER READING

The identified NPP bottlenecks can be grouped in the following categories:
• Increasing the energy densities in all nuclear island components:
o Fuel/Core: acceptance and First Time Engineering for annular and UN fuel and to increase energy density in Reactor vessel, Departure from Nucleate Boiling (DNB) and Reactor Pressure Vessel (RPV) fluence
o Steam generator: energy balance (Thot, Tcold, steam pressure), increase heat transfer (area or efficiency)
• Handling of increased energy density of the Nuclear Steam Supply System (NSSS) during normal operation and accident conditions:
o Capacity of Pressurizer
o Reactor Coolant Pumps
o Piping
o Containment
o Instrumentation and Control
• Handling of increased energy production by both the on-site and off-site BOP facilities:
o Turbine and Generator
o Condenser and Cooling Tower
o Circulation Pumps
o Steam line and feed-water line flow velocities
• Licensing / Acceptance:
o Safety analysis margin has be maintained
o Site permit limits
o Spent fuel pool
o Source term
o Backfit versus new licensing criteria
• Achieving favorable economics with capital charges about equal to combined cycle gas turbine plants and combined fuel and O&M charges less than current Generation II plants.


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