United States Nuclear Regulatory Commission - Protecting People and the Environment
Home > NRC Library > Document Collections > Fact Sheets > Backgrounder on Power Uprates for Nuclear Plants

Backgrounder on Power Uprates for Nuclear Plants

Printable Version

When the NRC licenses a commercial nuclear power plant, it 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.

Power Uprates

Utilities have used power uprates since the 1970s as a way to generate more electricity from their nuclear plants. As of April 2014, the NRC has approved 154 uprates, resulting in a gain of approximately 21,105 MWt (megawatts thermal) or 7,035 MWe (megawatts electric). These uprates are listed in Table 1 at the end of this document. Collectively, these uprates have added generating capacity equivalent to about seven new reactors.

To increase the power output of a reactor, typically a utility will refuel 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, which drives a turbine to generate electricity. Components such as pipes, valves, pumps, heat exchangers, electrical transformers and generators must be able to accommodate the higher power level. For example, a higher power level usually involves greater steam and water flow through the systems used to convert heat into electric power. These systems must be able to handle the increased flows.

Some licensees modify or replace components in order to accommodate a higher power level. Depending on the desired power increase and original equipment design, this may involve major plant modifications, such as the replacement of main turbines. All of these factors must be analyzed by the licensee as part of its license amendment request 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 complex technical analyses before approving an uprate request.

Types of Power Uprates

U.S. commercial reactors are designed with excess capacity to allow for a potential uprate. There are three types of uprates: 1) measurement uncertainty recapture power uprates, 2) stretch power uprates, and 3) extended power uprates.

Measurement uncertainty recapture power uprates increase the licensed power level by less than 2 percent. They are achieved by implementing improved techniques for calculating reactor power. This involves the use of state-of-the-art devices to more precisely measure the feedwater flow used to calculate reactor power. More precise measurements reduce the degree of uncertainty in the power level, helping analysts predict the ability of the reactor to be safely shut down under possible accident conditions.

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

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 transformers.

To top of page

Review Process

Since uprates change a reactor’s licensed power level, utilities seek 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. 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, the NRC reviews data and accident analyses submitted by a licensee to confirm the plant can operate safely at the higher power level.

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 applying for an extended uprate.

After a licensee submits an uprate application, the NRC informs the public through a notice in the Federal Register 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 technical staff thoroughly reviews the application and any public comments, while the Atomic Safety and Licensing Board (ASLB) considers any requests for hearings. When the staff completes its review, it issues a safety evaluation and another Federal Register notice to inform the public of its decision.

If the ASLB determines a hearing is required a separate legal process takes place, and the NRC staff provides technical information as 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 an uprate while a hearing is underway. The NRC issues a press release for any approved uprate.

Uprates—Completed, Under Review, Expected

The NRC has approved 154 uprates and typically has several applications for power uprates under review at any given time. Licensees responding to a December 2012 NRC survey indicated they plan to submit 3 applications for measurement uncertainty recapture uprates in the next five years. If these applications are approved, the resulting uprates would add another 172 MWt (58 MWe) to the nation's generating capacity. Lists of uprate applications approved, under review, and anticipated can be found in the three tables at the end of this fact sheet, and on the NRC’s website.

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 website.

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 environmental assessment.

April 2014

To top of page

Table 1 - Approved Power Uprates, April 2014

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

NO. PLANT % UPRATE MWt DATE APPROVED UPRATE TYPE
1 Calvert Cliffs 1 5.5 140 09/09/1977 S
2 Calvert Cliffs 2 5.5 140 10/19/1977 S
3 Millstone 2 5 140 06/25/1979 S
4 H. B. Robinson 4.5 100 06/29/1979 S
5 Fort Calhoun 5.6 80 08/15/1980 S
6 Crystal River 3 3.8 92 07/21/1981 S
7 St. Lucie 1 5.5 140 11/23/1981 S
8 St. Lucie 2 5.5 140 03/01/1985 S
9 Duane Arnold 4.1 65 03/27/1985 S
10 Salem 1 2 73 02/06/1986 S
11 North Anna 1 4.2 118 08/25/1986 S
12 North Anna 2 4.2 118 08/25/1986 S
13 Callaway 4.5 154 03/30/1988 S
14 TMI-1 1.3 33 07/26/1988 S
15 Fermi 2 4 137 09/09/1992 S
16 Vogtle 1 4.5 154 03/22/1993 S
17 Vogtle 2 4.5 154 03/22/1993 S
18 Wolf Creek 4.5 154 11/10/1993 S
19 Susquehanna 2 4.5 148 04/11/1994 S
20 Peach Bottom 2 5 165 10/18/1994 S
21 Limerick 2 5 165 02/16/1995 S
22 Susquehanna 1 4.5 148 02/22/1995 S
23 Nine Mile Point 2 4.3 144 04/28/1995 S
24 Columbia 4.9 163 05/02/1995 S
25 Peach Bottom 3 5 165 07/18/1995 S
26 Surry 1 4.3 105 08/03/1995 S
27 Surry 2 4.3 105 08/03/1995 S
28 Hatch 1 5 122 08/31/1995 S
29 Hatch 2 5 122 08/31/1995 S
30 Limerick 1 5 165 01/24/1996 S
31 V. C. Summer 4.5 125 04/12/1996 S
32 Palo Verde 1 2 76 05/23/1996 S
33 Palo Verde 2 2 76 05/23/1996 S
34 Palo Verde 3 2 76 05/23/1996 S
35 Turkey Point 3 4.5 100 09/26/1996 S
36 Turkey Point 4 4.5 100 09/26/1996 S
37 Brunswick 1 5 122 11/01/1996 S
38 Brunswick 2 5 122 11/01/1996 S
39 Fitzpatrick 4 100 12/06/1996 S
40 Farley 1 5 138 04/29/1998 S
41 Farley 2 5 138 04/29/1998 S
42 Browns Ferry 2 5 164 09/08/1998 S
43 Browns Ferry 3 5 164 09/08/1998 S
44 Monticello 6.3 105 09/16/1998 E
45 Hatch 1 8 205 10/22/1998 E
46 Hatch 2 8 205 10/22/1998 E
47 Comanche Peak 2 1 34 09/30/1999 MU
48 LaSalle 1 5 166 05/09/2000 S
49 LaSalle 2 5 166 05/09/2000 S
50 Perry 5 178 06/01/2000 S
51 River Bend 5 145 10/06/2000 S
52 Diablo Canyon 1 2 73 10/26/2000 S
53 Watts Bar 1.4 48 01/19/2001 MU
54 Byron 1 5 170 05/04/2001 S
55 Byron 2 5 170 05/04/2001 S
56 Braidwood 1 5 170 05/04/2001 S
57 Braidwood 2 5 170 05/04/2001 S
58 Salem 1 1.4 48 05/25/2001 MU
59 Salem 2 1.4 48 05/25/2001 MU
60 San Onofre 2 1.4 48 07/06/2001 MU
61 San Onofre 3 1.4 48 07/06/2001 MU
62 Susquehanna 1 1.4 48 07/06/2001 MU
63 Susquehanna 2 1.4 48 07/06/2001 MU
64 Hope Creek 1.4 46 07/30/2001 MU
65 Beaver Valley 1 1.4 37 09/24/2001 MU
66 Beaver Valley 2 1.4 37 09/24/2001 MU
67 Shearon Harris 4.5 138 10/12/2001 S
68 Comanche Peak 1 1.4 47 10/12/2001 MU
69 Comanche Peak 2 0.4 13 10/12/2001 MU
70 Duane Arnold 15.3 248 11/06/2001 E
71 Dresden 2 17 430 12/21/2001 E
72 Dresden 3 17 430 12/21/2001 E
73 Quad Cities 1 17.8 446 12/21/2001 E
74 Quad Cities 2 17.8 446 12/21/2001 E
75 Waterford 3 1.5 51 03/29/2002 MU
76 Clinton 20 579 04/05/2002 E
77 South Texas 1 1.4 53 04/12/2002 MU
78 South Texas 2 1.4 53 04/12/2002 MU
79 ANO-2 7.5 211 04/24/2002 E
80 Sequoyah 1 1.3 44 04/30/2002 MU
81 Sequoyah 2 1.3 44 04/30/2002 MU
82 Brunswick 1 15 365 05/31/2002 E
83 Brunswick 2 15 365 05/31/2002 E
84 Grand Gulf 1.7 65 10/10/2002 MU
85 H. B. Robinson 1.7 39 11/05/2002 MU
86 Peach Bottom 2 1.62 56 11/22/2002 MU
87 Peach Bottom 3 1.62 56 11/22/2002 MU
88 Indian Point 3 1.4 42.4 11/26/2002 MU
89 Point Beach 1 1.4 21.5 11/29/2002 MU
90 Point Beach 2 1.4 21.5 11/29/2002 MU
91 Crystal River 3 0.9 24 12/04/2002 S
92 D.C. Cook 1 1.66 54 12/20/2002 MU
93 River Bend 1.7 52 01/31/2003 MU
94 D.C. Cook 2 1.66 57 05/02/2003 MU
95 Pilgrim 1.5 30 05/09/2003 MU
96 Indian Point 2 1.4 43 05/22/2003 MU
97 Kewaunee 1.4 23 07/08/2003 MU
98 Hatch 1 1.5 41 09/23/2003 MU
99 Hatch 2 1.5 41 09/23/2003 MU
100 Palo Verde 2 2.9 114 09/29/2003 S
101 Kewaunee 6 99 02/27/2004 S
102 Palisades 1.4 35.4 06/23/2004 MU
103 Indian Point 2 3.26 101.6 10/27/2004 S
104 Seabrook 5.2 176 02/28/2005 S
105 Indian Point 3 4.85 148.6 03/24/2005 S
106 Waterford 8 275 04/15/2005 S
107 Palo Verde 1 2.9 114 11/16/2005 S
108 Palo Verde 3 2.9 114 11/16/2005 S
109 Vermont Yankee 20 319 03/02/2006 E
110 Seabrook 1.7 61 05/22/2006 MU
111 Ginna 16.8 255 07/11/2006 E
112 Beaver Valley 1 8 211 07/19/2006 E
113 Beaver Valley 2 8 211 07/19/2006 E
114 Browns Ferry 1 5 165 03/06/2007 S
115 Crystal River 3 1.6 41 12/26/2007 MU
116 Susquehanna 1 13 463 01/30/2008 E
117 Susquehanna 2 13 463 01/30/2008 E
118 Vogtle 1 1.7 60.6 02/27/2008 MU
119 Vogtle 2 1.7 60.6 02/27/2008 MU
120 Hope Creek 15 501 05/14/2008 E
121 Comanche Peak 1 4.5 154 06/27/2008 S
122 Comanche Peak 2 4.5 154 06/27/2008 S
123 Cooper 1.6 38 06/30/2008 MU
124 Davis-Besse 1.6 45 06/30/2008 MU
125 Millstone 3 7 239 08/12/2008 S
126 Calvert Cliffs 1 1.4 37 07/22/2009 MU
127 Calvert Cliffs 2 1.4 37 07/22/2009 MU
128 North Anna 1 1.6 47 10/22/2009 MU
129 North Anna 2 1.6 47 10/22/2009 MU
130 Prairie Island 1 1.6 27 08/18/2010 MU
131 Prairie Island 2 1.6 27 08/18/2010 MU
132 LaSalle 1 1.6 57 09/16/2010 MU
133 LaSalle 2 1.6 57 09/16/2010 MU
134 Surry 1 1.6 41 09/24/2010 MU
135 Surry 2 1.6 41 09/24/2010 MU
136 Limerick 1 1.6 57 04/08/2011 MU
137 Limerick 2 1.6 57 04/08/2011 MU
138 Point Beach 1 17 260 05/03/2011 E
139 Point Beach 2 17 260 05/03/2011 E
140 Nine Mile Point 2 15 521 12/22/2011 E
141 Shearon Harris 1.7 48 05/30/2012 MU
142 Turkey Point 3 15.0 344 06/15/2012 E
143 Turkey Point 4 15.0 344 06/15/2012 E
144 St. Lucie 1 11.9 320 07/09/2012 E
145 Grand Gulf 1 13.1 510 07/18/2012 E
146 St. Lucie 2 11.9 320 09/24/2012 E
147 McGuire 1 1.7 58 05/16/2013 MU
148 McGuire 2 1.7 58 05/16/2013 MU
149 Monticello 12.9 229 12/09/2013 E
150 Braidwood 1 1.6 58.4 02/07/2014 MU
151 Braidwood 2 1.6 58.4 02/07/2014 MU
152 Byron 1 1.6 58.4 02/07/2014 MU
153 Byron 2 1.6 58.4 02/07/2014 MU
154 Fermi 2 1.6 56 02/10/2014 MU
  Total MWt   21,104.8    
  Total MWe   7,034.9    
           

To top of page

Table 2 - Power Uprates Under Review, April 2014

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

No. Plant % Uprate MWt Submittal
Date
Projected Completion
Date
Type
1 Browns Ferry 2 14.3 494 06/25/2004 On Hold4 E
2 Browns Ferry 3 14.3 494 06/25/2004 On Hold4 E
3 Browns Ferry 1 14.3 494 06/28/2004 On Hold4 E
4 Oconee 1 1.6 42 09/20/2011 On Hold5 MU
5 Oconee 2 1.6 42 09/20/2011 On Hold5 MU
6 Oconee 3 1.6 42 09/20/2011 On Hold5 MU
7 Peach Bottom 2 12.4 437 09/28/2012 September 2014 E
8 Peach Bottom 3 12.4 437 09/28/2012 September 2014 E
    TOTAL 2,482      
    TOTAL MWe 827.3      

To top of page

Table 3 - Expected Power Uprate Applications

Fiscal Year Total Power Uprates Expected Measurement Uncertainty Recapture Power Uprates Stretch Power Uprates Extended Power Uprates Megawatts
Thermal
Approximate
Megawatts Electric
2013 0 0 0 0 0 0
2014 2 2 0 0 116 39
2015 0 0 0 0 0 0
2016 1 1 0 0 56 19
2017 0 0 0 0 0 0
TOTAL 3 3 0 0 172 58

To top of page

Page Last Reviewed/Updated Friday, February 04, 2011