BACKGROUNDER

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Power Uprates for Nuclear Plants 

Introduction 

When the NRC issues a license for a commercial nuclear power plant, the agency sets limits on the 

maximum heat output, or power level, for the reactor core. This power level plays an important role in 

many of the analyses that demonstrate plant safety, so the NRC’s permission is required before a plant 

can change its maximum power level. A “power uprate” only occurs after the NRC approves a 

commercial nuclear power plant’s request to increase its power. 

Background 

Utilities have used power uprates since the 1970s as a way to generate more electricity from their nuclear 

plants. As of January 2008, the NRC has approved 116 uprates, resulting in a gain of approximately 

15,600 MWt (megawatts thermal) or 5,200 MWe (megawatts electric) at existing plants. These uprates 

are listed in Table 1 at the end of this document. Collectively, these uprates have added generating 

capacity at existing plants that is equivalent to more than five new reactors. 

Discussion 

To increase the power output of a reactor, typically a utility will refuel a reactor with either slightly more 

enriched uranium fuel or a higher percentage of new fuel. This enables the reactor to produce more 

thermal energy and therefore more steam, driving a turbine generator to produce electricity. In order to 

accomplish this, components such as pipes, valves, pumps, heat exchangers, electrical transformers and 

generators must be able to accommodate the conditions that would exist at the higher power level. For 

example, a higher power level usually involves higher steam and water flow through the systems used in 

converting the thermal power into electric power. These systems must be capable of accommodating the 

higher flows. 

In some instances, licensees will modify and/or replace components in order to accommodate a higher 

power level. Depending on the desired increase in power level and original equipment design, this can 

involve major modifications to the plant such as the replacement of main turbines. All of these factors 

must be analyzed by the licensee as part of their request to amend their license for the uprate. The 

analyses must demonstrate that the proposed new configuration remains safe and that measures continue 

to be in place to protect the health and safety of the public. The NRC=s technical and legal staffs review 

these analyses, which span many technical disciplines and may be complex, before approving a request 

for a power uprate.
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Types of Power Uprates

The design of every U.S. commercial reactor has excess capacity needed to potentially allow for an 

uprate, which can fall into one of three categories: 1) measurement uncertainty recapture power uprates, 2) 

stretch power uprates, and 3) extended power uprates. 

1) Measurement uncertainty recapture power uprates are power increases less than 2 percent of the 

licensed power level, and are achieved by implementing enhanced techniques for calculating reactor 

power. This involves the use of state-of-the-art devices to more precisely measure feedwater flow which is 

used to calculate reactor power. More precise measurements reduce the degree of uncertainty in the power 

level which is used by analysts to predict the ability of the reactor to be safely shut down under possible 

accident conditions. 

2) Stretch power uprates are typically between 2 percent and 7 percent, with the actual increase in power 

depending on a plant design’s specific operating margin. Stretch power uprates usually involve changes to 

instrumentation settings but do not involve major plant modifications. 

3) Extended power uprates are greater than stretch power uprates and have been approved for increases 

as high as 20 percent. Extended power uprates usually require significant modifications to major pieces of 

non-nuclear equipment such as high-pressure turbines, condensate pumps and motors, main generators, 

and/or transformers. 

Review Process

Since uprates affect a reactor’s licensed power level, utilities apply for NRC permission to amend their 

operating license in order to implement a power uprate. The process for requesting and approving a 

change to a plant's power level is governed by 10 CFR 50.90-92. These regulations are available on the 

agency’s Web site at: http://www.nrc.gov/reading-rm/doc-collections/cfr/part050/. The applications and 

reviews are complex and involve many areas of expertise in the NRC’s Offices of Nuclear Reactor 

Regulation and General Counsel. Some reviews may also involve the Office of Nuclear Regulatory 

Research and the Advisory Committee on Reactor Safeguards (ACRS). In evaluating a power uprate 

request, NRC reviews data and accident analyses submitted by a licensee to confirm that the plant can 

operate safely at the higher power level. Reviews of power uprate requests are a high priority. 

The NRC uses a review standard for extended power uprates (RS-001, December 2003), that has been 

endorsed by the ACRS. The standard provides a comprehensive process and technical guidance for 

reviews by the NRC staff, and provides useful information to licensees considering applying for an 

extended uprate. 

After a licensee submits an uprate application, the NRC places a notice in the Federal Register to notify 

the public that the agency is considering the application. The public has 30 days to comment on the 

licensee's request and 60 days to request a hearing where the application could be contested. The NRC 

thoroughly reviews the application and any public comments, while the Atomic Safety and Licensing 

Board (ASLB) considers any requests for hearings. NRC technical staff complete their review while 

considering and addressing any public comments, issuing a safety evaluation and another Federal Register

notice to inform the public. If the ASLB determines a hearing is required, a separate legal process takes 

place, and NRC staff provides technical information, if needed. The safety evaluation and any hearing 

rulings form the basis for the NRC’s final decision on the uprate request, although the staff can authorize 
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an uprate while a hearing is underway. The NRC issues a press release for any approved uprate, and an 

updated list of approved uprates is available on the NRC’s Web site at: 

http://www.nrc.gov/reactors/operating/licensing/power-uprates/approved-applications.html. 

The NRC usually has several applications for power uprates under review at any given time. The latest list 

of applications under review is on the NRC’s Web site at: 

http://www.nrc.gov/reactors/operating/licensing/power-uprates/pending-applications.html. 

Expected Uprate Applications

Licensee responses to a September 2007 NRC survey indicate they plan to submit 24 power uprate 

applications in the next five years, including 17 extended uprates and 7 measurement uncertainty 

recapture uprates. If these applications are approved, the resulting uprates would add another 5,254 MWt 

(1,751 MWe) to the nation's generating capacity. Anticipated future applications can be found in Table 3 

at the end of this fact sheet, and updates will be on the NRC’s Web site at: 

http://www.nrc.gov/reactors/operating/licensing/power-uprates/expected-applications.html. 

Public Involvement

The NRC welcomes public involvement in our activities as part of our strong, fair oversight of the nuclear 

industry. The public’s opportunities to participate in the power uprate arena include: 

• Pre-application meetings, where licensees discuss their uprate plans with NRC staff (some 

portions of these meetings may be closed to the public to discuss proprietary information); 

• Comments related to an application and requests for a hearing on the application. 

• Briefings to the ACRS on the results of the staff's review of the applications (some portions of 

these meetings may be closed to the public to discuss proprietary information). ACRS meeting 

schedules are available on the NRC’s Web site at this address: http://www.nrc.gov/readingrm/doc-collections/acrs/agenda/. 

For each extended power uprate, the NRC staff typically issues a draft environmental assessment for a 30-

day public comment period. The NRC staff considers and addresses all comments before finalizing the 

draft environmental assessment. 

Table 1 - Approved Power Uprates, February 2008

(TYPE – S = Stretch; E = Extended; MU = Measurement Uncertainty Recapture) 

No. Plant % Uprate MWt Year Approved TYPE

1 Calvert Cliffs 1 5.5 140 1977 S 

2 Calvert Cliffs 2 5.5 140 1977 S 

3 Millstone 2 5 140 1979 S 

4 H. B. Robinson 4.5 100 1979 S 

5 Fort Calhoun 5.6 80 1980 S 

6 St. Lucie 1 5.5 140 1981 S 
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No. Plant % Uprate MWt Year Approved TYPE

7 St. Lucie 2 5.5 140 1985 S 

8 Duane Arnold 4.1 65 1985 S 

9 Salem 1 2 73 1986 S 

10 North Anna 1 4.2 118 1986 S 

11 North Anna 2 4.2 118 1986 S 

12 Callaway 4.5 154 1988 S 

13 TMI-1 1.3 33 1988 S 

14 Fermi 2 4 137 1992 S 

15 Vogtle 1 4.5 154 1993 S 

16 Vogtle 2 4.5 154 1993 S 

17 Wolf Creek 4.5 154 1993 S 

18 Susquehanna 2 4.5 148 1994 S 

19 Peach Bottom 2 5 165 1994 S 

20 Limerick 2 5 165 1995 S 

21 Susquehanna 1 4.5 148 1995 S 

22 Nine Mile Point 2 4.3 144 1995 S 

23 WNP-2 4.9 163 1995 S 

24 Peach Bottom 3 5 165 1995 S 

25 Surry 1 4.3 105 1995 S 

26 Surry 2 4.3 105 1995 S 

27 Hatch 1 5 122 1995 S 

28 Hatch 2 5 122 1995 S 

29 Limerick 1 5 165 1996 S 

30 V. C. Summer 4.5 125 1996 S 

31 Palo Verde 1 2 76 1996 S 

32 Palo Verde 2 2 76 1996 S 

33 Palo Verde 3 2 76 1996 S 

34 Turkey Point 3 4.5 100 1996 S 

35 Turkey Point 4 4.5 100 1996 S 

36 Brunswick 1 5 122 1996 S 
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No. Plant % Uprate MWt Year Approved TYPE

37 Brunswick 2 5 122 1996 S 

38 Fitzpatrick 4 100 1996 S 

39 Farley 1 5 138 1998 S 

40 Farley 2 5 138 1998 S 

41 Browns Ferry 2 5 164 1998 S 

42 Browns Ferry 3 5 164 1998 S 

43 Monticello 6.3 105 1998 E 

44 Hatch 1 8 205 1998 E 

45 Hatch 2 8 205 1998 E 

46 Comanche Peak 2 1 34 1999 MU 

47 LaSalle 1 5 166 2000 S 

48 LaSalle 2 5 166 2000 S 

49 Perry 5 178 2000 S 

50 River Bend 5 145 2000 S 

51 Diablo Canyon 1 2 73 2000 S 

52 Watts Bar 1.4 48 2001 MU 

53 Byron 1 5 170 2001 S 

54 Byron 2 5 170 2001 S 

55 Braidwood 1 5 170 2001 S 

56 Braidwood 2 5 170 2001 S 

57 Salem 1 1.4 48 2001 MU 

58 Salem 2 1.4 48 2001 MU 

59 San Onofre 2 1.4 48 2001 MU 

60 San Onofre 3 1.4 48 2001 MU 

61 Susquehanna 1 1.4 48 2001 MU 

62 Susquehanna 2 1.4 48 2001 MU 

63 Hope Creek 1.4 46 2001 MU 

64 Beaver Valley 1 1.4 37 2001 MU 

65 Beaver Valley 2 1.4 37 2001 MU 

66 Shearon Harris 4.5 138 2001 S 
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No. Plant % Uprate MWt Year Approved TYPE

67 Comanche Peak 1 1.4 47 2001 MU 

68 Comanche Peak 2 0.4 13 2001 MU 

69 Duane Arnold 15.3 248 2001 E 

70 Dresden 2 17 430 2001 E 

71 Dresden 3 17 430 2001 E 

72 Quad Cities 1 17.8 446 2001 E 

73 Quad Cities 2 17.8 446 2001 E 

74 Waterford 3 1.5 51 2002 MU 

75 Clinton 20 579 2002 E 

76 South Texas 1 1.4 53 2002 MU 

77 South Texas 2 1.4 53 2002 MU 

78 ANO-2 7.5 211 2002 E 

79 Sequoyah 1 1.3 44 2002 MU 

80 Sequoyah 2 1.3 44 2002 MU 

81 Brunswick 1 15 365 2002 E 

82 Brunswick 2 15 365 2002 E 

83 Grand Gulf 1.7 65 2002 MU 

84 H. B. Robinson 1.7 39 2002 MU 

85 Peach Bottom 2 1.62 56 2002 MU 

86 Peach Bottom 3 1.62 56 2002 MU 

87 Indian Point 3 1.4 42.4 2002 MU 

88 Point Beach 1 1.4 21.5 2002 MU 

89 Point Beach 2 1.4 21.5 2002 MU 

90 Crystal River 3 0.9 24 2002 S 

91 D.C. Cook 1 1.66 54 2002 MU 

92 River Bend 1.7 52 2003 MU 

93 D.C. Cook 2 1.66 57 2003 MU 

94 Pilgrim 1.5 30 2003 MU 

95 Indian Point 2 1.4 43 2003 MU 

96 Kewaunee 1.4 23 2003 MU 

97 Hatch 1 1.5 41 2003 MU 
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No. Plant % Uprate MWt Year Approved TYPE

98 Hatch 2 1.5 41 2003 MU 

99 Palo Verde 2 2.9 114 2003 S 

100 Kewaunee 6.0 99 2004 S 

101 Palisades 1.4 35 2004 MU 

102 Indian Point 2 3.2 101.6 2004 S 

103 Seabrook 5.2 176 2005 S 

104 Indian Point 3 4.85 148.6 2005 S 

105 Waterford 8.0 275 2005 E 

106 Palo Verde 1 2.9 114 2005 S 

107 Palo Verde 3 2.9 114 2005 S 

108 Vermont Yankee 20 319 2006 E 

109 Seabrook 107 61 2006 MU 

110 Ginna 16.8 255 2006 E 

111 Beaver Valley 1 8 211 2006 E 

112 Beaver Valley 2 8 211 2006 E 

113 Browns Ferry 1 5 165 2007 S 

114 Crystal River 3 1.6 41 2007 MU 

115 Susquehanna 1 13 463 2008 E 

116 Susquehanna 2 13 463 2008 E 

Table 2 - Power Uprates Under Review, February 2008 

(TYPE -- S = Stretch; E = Extended; MU = Measurement Uncertainty Recapture) 

No. Plant % Uprate MWt Submittal 

Date

Projected Completion 

Date

Type

1 Browns Ferry 2 15 494 06/25/04 Spring 2008 E 

2 Browns Ferry 3 15 494 06/25/04 Spring 2008 E 

3 Browns Ferry 1 15 494 06/28/04 Spring 2008 E 

4 Hope Creek 15 501 09/18/06 Spring 2008 E 

5 Davis-Besse 1.6 45 04/12/07 TBD MU 

6 Millstone 3 7.0 239 07/13/07 08/15/08 S 

7 Comanche Peak 1 4.5 154 08/28/07 07/09/08 S 

8 Comanche Peak 2 4.5 154 08/27/07 07/09/08 S 

9 Vogtle 1 1.7 61 08/27/07 03/01/08 MU 
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No. Plant % Uprate MWt Submittal 

Date

Projected Completion 

Date

Type

10 Vogtle 2 1.7 61 08/24/07 03/01/08 MU 

11 Cooper 1.6 38 11/19/07 06/20/08 MU 

Table 3 - Expected Future Submittals for Power Uprates, December 2007

Fiscal 

Year

Total 

Uprates 

Expected

Measurement 

Uncertainty 

Recapture 

Uprates

Stretch Power 

Uprates

Extended Power 

Uprates

Megawatts 

Thermal

Approximate 

Megawatts 

Electric

2008 4 2 0 2 804 268 

2009 11 5 0 6 1966 655 

2010 6 0 0 6 1368 456 

2011 2 0 0 2 895 298 

2012 1 0 0 1 221 74

TOTAL 24 7 0 17 5,254 1,751

Additional Information

Additional information and guidance for power uprate license amendment request submittals can be found 

on the NRC=s Power Uprate Web page at this address: 

http://www.nrc.gov/reactors/operating/licensing/power-uprates.html. 

February 2008