Nuclear Plant Performance:
What Does Restructuring
Have To Do With It?
Published May 2007
2301 M Street NW
Washington, D.C. 20037-1484
202/467-2900
www.APPAnet.org
©2007 by the American Public Power Association.
All rights reserved.
Published by the American Public Power Association
2301 M Street, N.W., Washington, D.C. 20037-1484;
202-467-2900; fax: 202-467-2910; www.APPAnet.org
2
Nuclear Plant Performance: What Does
Restructuring Have To Do With It?
Proponents of deregulation of wholesale electricity markets often claim that a benefit of
deregulation is improvement in the performance of generating plants. One method used
to measure the improvements in plant operation is to track increases in capacity factors.
Capacity factor measures how much output a plant produces in a period compared to the
plant’s potential output. The more intensely a plant is used, the closer it will approach a
capacity factor of 100 percent. Base load plants – those plants that are dispatched first –
have higher capacity factors than do intermediate and peaking plants, which are
dispatched as needed to meet increasing levels of demand.
The operating characteristics of nuclear plants make them ideal for base load generation.
Nuclear units are large – the median capacity of the 103 units in the U.S. is 1,000
megawatts (MW); nuclear plants have low operations and maintenance costs; and it is
very inefficient to take nuclear units on and off line.
This report studies how capacity factors for nuclear plants differ across regions and over
time. It attempts to answer these questions:
• Are capacity factors different in regulated and deregulated wholesale markets?
• Has deregulation improved capacity factors?
• How have plant sales or transfers from a regulated utility to a non-regulated
generator affected capacity factors?
The table and accompanying chart, below, show how weighted mean (average) capacity
factors have changed in each NERC region from 1995-2005. (For definitions of each
region, see the appendix.) Capacity factor was calculated using data in the Energy
Velocity generating capacity database, accessed in March 2007. Capacity factor equals
actual generation divided by potential generation, and potential generation is calculated
by multiplying a plant’s summer capacity by the number of hours in a year (8,760).
Average Capacity Factors for Nuclear Plants
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
ECAR
78.1%
76.0%
70.5%
68.7%
88.0%
71.2%
82.1%
82.3%
81.8%
91.0%
91.0%
ERCOT
87.1%
86.2%
90.0%
93.2%
88.6%
90.5%
92.0%
85.8%
80.6%
97.0%
91.9%
FRCC
84.6%
75.0%
85.6%
91.6%
93.0%
94.6%
90.9%
98.7%
90.5%
91.3%
84.1%
MAAC
74.1%
71.0%
73.9%
84.8%
88.7%
90.9%
83.5%
92.2%
91.7%
91.7%
93.2%
MAIN
72.2%
67.5%
52.1%
67.9%
88.2%
94.5%
85.1%
92.9%
94.5%
90.3%
89.8%
MRO
83.9%
86.5%
80.6%
79.9%
93.4%
86.1%
81.9%
94.4%
84.9%
94.4%
86.8%
NPCC
62.3%
66.1%
52.7%
61.2%
81.9%
80.5%
85.6%
87.5%
91.3%
93.2%
92.5%
SERC
82.5%
84.2%
84.6%
89.9%
89.4%
91.1%
91.3%
92.9%
90.6%
93.2%
90.9%
WECC
79.5%
84.9%
81.9%
89.0%
86.6%
91.9%
86.7%
91.1%
88.2%
82.8%
85.4%
Average Capacity Factors by NERC Region
100%
Capacity Factor
90%
80%
ECAR
ERCOT
FRCC
70%
MAAC
MAIN
MRO
60%
NPCC
SERC
WECC
50%
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
Periodically, nuclear units must be taken off line for a number of weeks for refueling
outages, and often these outages are extended in order to perform various maintenance
tasks. The result is a normal variation in a nuclear plant’s annual capacity factor, which
will also depend on the number of units at a plant and the outage cycle. The effect of
outages will be more evident in the average calculations for regions with a small number
of plants.
As the chart shows, there is currently a narrow gap between regions. In 2005, the MAAC
region had the highest capacity factor, with an average of 93.2 percent, while FRCC’s
capacity factor of 84.1 percent was the lowest among the regions.
The chart also demonstrates that several regions have witnessed significant improvements
since the late 1990s. In particular, capacity factors have risen dramatically in NPCC and
MAIN. Average capacity factor rose from a low of 52.7 percent in 1997 to over 90
percent by 2003 in NPCC and from a low of 52.1 percent in 1997 to over 90 percent in
2000 in MAIN.
In ECAR, average capacity factor has improved, but still shows a great deal of variation
over time. After averaging in the high-60s to high-70s from 1995 to 1998, capacity factor
reached 88 percent in 1999. Subsequently, capacity factor fell to 71 percent in 2000, rose
again to 81 percent in 2001, and exceeded 90 percent in 2004 and 2005. MAAC also saw
a steady increase in capacity factor after 1997. The average was in the low-70s from 1995
to 1997, rose to 84.8 percent in 1998 and reached 93.2 percent in 2005.
In ECAR, five of the six nuclear plants operated for one or more years at low capacity
factors: Beaver Valley (1998), Davis-Besse (2002-2003), Donald Cook (1997 and 2000),
2
Fermi (1995-1997) and Palisades (2001). In contrast, in the other three regions, a few
select plants were responsible for the low average capacity factors in 1995-2000 (the first
half of the time period). Recalculating regional averages without these few plants shows
that the remaining plants in the region achieved relatively high and stable capacity factors
over this time period. Thus it does not appear that the switch to deregulated wholesale
markets resulted in significantly improved capacity factors for most plants.
In MAAC, the Salem Generating Station alone made a deep impact on the entire region’s
average. The plant operated at extremely low capacity factors from 1995 to 1997, and if it
is removed from the database, average capacity factor for the region’s seven other nuclear
plants remains relatively steady.
MAAC Capacity
Factor
All Plants
Without Salem
1995
74.1%
84.4%
1996
71.0%
85.6%
1997
73.9%
86.4%
1998
84.8%
87.3%
1999
88.7%
90.0%
2000
90.9%
91.4%
In the NPCC region, the Millstone plant had extremely low capacity factors between
1996 and 1998. Its capacity factor improved to 72.1 percent in 1999 and to over 90
percent in 2000. The Indian Point 2 power plant experienced capacity factors between 30
and 40 percent in 1997 and 1998. After operating at only 12 percent in 2000, capacity
factor was over 90 percent in 2001. As shown below, removing these two plants results in
a relatively steady capacity factor for the remaining seven plants that operated for the full
1995-2005 time period. (The low capacity factor in 1995 is attributable to the Maine
Yankee plant, which operated for very few hours in 1995 and was retired at the end of
1996. The Haddam Neck plant also did not operate after 1996.)
NPCC Capacity Factor
All plants
Without Indian Point 2 and Millstone
1995
62.3%
61.7%
1996
66.1%
80.0%
1997
52.7%
76.8%
1998
61.2%
82.7%
1999
81.9%
83.9%
2000
80.5%
86.6%
In the MAIN region, three plants, Clinton, LaSalle, and Zion, each had very low capacity
factors in the late-1990s. Clinton registered negative capacity factors in 1997 and 1998,
as did the Zion plant in 1998. (Negative capacity factor indicates that a plant consumed
more power than it produced.) LaSalle’s capacity factor was negative in 1997, and just
over 30 percent in 1998. After 1998, Zion ceased operating. Capacity factors at both the
Clinton and LaSalle plants greatly improved beginning in 1999, with the LaSalle plant
achieving a capacity factor of over 90 percent in 2000 and the Clinton plant reaching 97
percent in 2001.
If the Clinton, LaSalle and Zion plants are removed from the database, average capacity
factor improves from 52.1 percent to 71.4 percent in 1997 and from 67.9 percent to 78.6
in 1998. Capacity factor for eight remaining plants is relatively stable until it jumps
significantly in 1999.
3
MAIN Capacity Factor
All plants
Without Clinton, LaSalle and Zion
1995
72.2%
72.7%
1996
67.5%
69.4%
1997
52.1%
71.4%
1998
67.9%
78.6%
1999
88.2%
91.4%
2000
94.5%
95.2%
As discussed in the next two sections, some of the poor performing plants noted above
did improve following their sale or transfer to non-regulated entities – for example,
Clinton and Indian Point 2. In contrast, the Salem, LaSalle and Millstone plants achieved
high capacity factors prior to their sale or transfer.
Deregulation and Capacity Factor
A number of plants, especially in the NPCC region, have been sold to non-regulated
companies such as Exelon Corp, Constellation Energy Group, FPL Group, and Dominion
Resources. The following table and chart show annual capacity factors for the ten nuclear
plants that had at least a majority share of their controlling interest sold to non-regulated
utilities between 1999 and 2003. (Plant sales completed in 2004 or 2005 were excluded,
because they are too recent for any trends in improvement to show up.) The year the plant
was sold is shown in bold.
Change in Capacity Factors: Plants Sold to Non-regulated Generators
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
Three
Mile
Island
90.0
99.8
83.4
99.5
89.3
100.0
83.2
103.0
87.3
102.0
95.2
Pilgrim
77.0
90.7
73.6
97.3
76.8
94.4
88.3
98.8
83.7
98.7
91.3
Clinton
75.4
66.2
-1.5
-1.2
58.6
85.2
97.3
88.6
97.6
87.7
95.3
Indian
Point 3
17.1
68.4
51.0
90.1
85.8
98.7
94.2
97.8
87.6
100.0
92.6
Fitzpatrick
68.9
75.5
90.0
73.0
89.3
81.5
96.8
89.5
94.9
86.9
95.3
Oyster
Creek
98.0
81.7
95.7
81.6
100.0
77.2
98.4
94.9
99.2
89.3
99.1
Millstone
65.1
14.8
-0.5
15.7
72.1
92.9
75.0
84.9
91.5
93.5
87.2
Indian
Point 2
59.6
95.5
38.5
30.2
89.1
12.1
92.9
88.6
97.2
86.7
103.1
Nine
Mile
Point
75.1
86.7
75.3
79.0
80.3
79.7
76.5
86.1
89.6
87.7
93.8
Vermont
Yankee
96.8
87.4
98.1
77.3
92.6
102.6
94.1
53.4
100.0
86.8
91.9
4
Seabrook
83.2
97.0
78.4
82.4
85.3
77.9
85.5
91.4
91.2
100.0
90.0
Change in Capacity Factor: Plants Sold to Non-regulated Generators
100
90
Three Mile Island
80
Pilgrim
70
Capacity Factor
Clinton
60
Indian
Point 3
Fitzpatrick
50
Oyster
Creek
Millstone
40
30
Nine Mile Point
Vermont Yankee
20
Seabrook
10
Indian Point 2
0
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
For most plants, the sale to a non-regulated entity did not significantly affect capacity
factors. There are a few exceptions. Capacity factors for both the Clinton plant in Illinois
and the Indian Point 2 unit in New York began steadily reaching 85 percent or above
after the plants were sold to non-regulated entities. The Millstone plant in Connecticut
also achieved consistently high capacity factors after its sale, although the plant had
achieved a 93 percent capacity factor in the year prior to its sale. The Nine Mile plant
also achieved a modest improvement.
The other plants, however, saw little change. Indian Point 3 in New York had already
improved its capacity factor before the completion of its sale in November 2000.
Vermont Yankee’s capacity factor improved from 53.4 percent in 2002, the year it was
sold, to 100 percent the following year, but it had achieved extremely high capacity
factors in the years immediately before it was sold. Several other plants – Pilgrim
(Massachusetts), Fitzpatrick (New York) and Oyster Creek (New Jersey) – also had high
capacity factors in the years immediately before and after they were sold.
A second group of plants were not sold, but instead transferred from regulated to
unregulated service. The trend in capacity factors for the 12 plants transferred to
unregulated affiliates between 2000 and 2002 is similar to the plants that were sold to
unregulated entities, as shown in the table below. The year the plant was transferred is
indicated in bold.
5
Change in Capacity Factors: Nuclear Plants Transferred from Regulated to Non-Regulated
Affiliates
Calvert
Cliffs
86.7
80.8
88.6
89.4
89.2
92.4
41.5
81.3
91.8
97.3
96.8
Susquehanna
80.5
86.7
86.6
84.5
85.6
90.0
92.0
89.6
91.6
90.5
91.7
Salem
23.4
-0.4
12.5
72.6
82.0
88.4
88.4
87.4
88.3
85.9
90.9
Dresden
38.8
36.9
70.0
86.5
90.1
95.5
86.3
98.1
91.8
82.7
90.6
Quad
Cities
62.1
54.0
60.7
51.6
96.3
91.8
92.8
91.1
97.2
83.6
87.7
Byron
80.9
74.6
82.8
83.8
92.2
98.6
48.9
92.5
97.6
96.7
94.9
Braidwood
82.1
79.3
83.0
88.0
96.6
95.7
100.0
97.5
96.8
96.4
97.0
LaSalle
72.5
53.7
-1.0
32.8
84.4
94.7
93.3
89.9
92.4
95.0
94.3
Limerick
82.6
85.4
88.1
83.6
91.4
94.3
93.0
97.0
97.6
97.0
95.1
Peach
Bottom
83.4
89.0
89.5
85.9
94.1
94.2
89.0
96.5
95.0
96.3
94.4
Comanche
Peak
87.7
77.9
90.7
92.3
89.7
95.2
94.7
85.7
91.8
98.3
94.9
Change in Capacity Factors: Plants Transferred to Non-Regulated Affiliates
100
90
80
70
Capacity Factor
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
Hope
Creek
76.9
73.3
69.7
94.9
83.7
78.8
87.6
96.2
79.0
65.4
83.5
Hope Creek
60
Calvert Cliffs
Susque-hanna
50
Salem
Dresden
40
Quad Cities
30
Byron
Braidwood
20
LaSalle
Limerick
10
Peach Bottom
Comanche Peak
0
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
Once again, a few plants stand out as having made significant improvement. However, in
most cases, the plant’s capacity factor showed improvement before it was transferred.
For example, both the LaSalle (Illinois) and Salem (New Jersey) plants have steadily
achieved high capacity factors after their transfer, but both plants had already greatly
improved their performance. The LaSalle plant’s capacity factor improved from zero in
1997 to 84 percent in 1999 – two years before it was transferred to non-regulated service.
The Salem plant’s capacity factor rose from zero in 1996 to over 80 percent in 1999, the
6
year before it was transferred. The same pattern occurs with two other Illinois plants –
Dresden and Quad Cities – that had poor performance in the mid-1990s.
Conclusion
There is only a small variance in mean capacity factors across all regions of the country.
There has been improvement in some regions, but generally, only a handful of plants
account for the improved capacity factors in these regions. Although a few plants
significantly improved their capacity factors when they were sold or transferred from
regulated to non-regulated utilities, most of the sales and transfers did not result in large
gains in plant capacity factors. Some of the non-regulated plants did become more
consistent in achieving relatively high capacity factors. In general, the experience has
been improved capacity factors across most all regions, regardless of the regulatory
framework.
7
APPENDIX ONE – REGIONAL DEFINITIONS
The regions used for this report correspond to regions of the North American Electric Reliability Council (NERC)
as specified below.
“Region”
Northeast
Corresponding NERC Region(s)
NPCC - Northeast Power Coordinating Council
MAAC - Mid-Atlantic Area Council
Southeast
SERC - Southeastern Electric Reliability Council
FRCC – Florida Reliability Coordinating Council
North Central/
Plains
ECAR - East Central Area Reliability Coordination Agreement
MAIN – Mid-America Interconnected Network
MRO – Midwest Reliability Organization
Southwest
SPP – Southwest Power Pool
ERCOT – Electric Reliability Council of Texas
West
WECC - Western Electricity Coordinating Council
ASCC - Alaska Systems Coordinating Council
8