NRC has approved 112 power uprates as of Feb 2007, totalling 4845 MW [Ref: NRC staff briefing, March 8, 2007 -- ML070730657]
March 3, 2006
October 3, 2005
NRC tells utility that combining MUR with SPU application might cause unnecessary complications
At an August 29 meeting at NRC HQ in Rockville, Nebraska Public Power District discussed its plan to submit a combined measurement uncertainty recapture (MUR) power uprate application with a stretch power uprate (SPU) application. The NRC staff noted that combining the MUR with the SPU application might cause unnecessary complications in establishing work responsibilities, use of review guidelines, and tracking various metrics and goals.
[Ref: DyLanne D. Duvigneaud (NRC project manager), "Summary of August 29, 2005, category 1 meeting with NPPD to discuss CNS strategic initiatives", NRC memo, October 3, 2005 - ML052620239]
May 26, 2005
* Sweden - PRM upgrades at Forsmarks will support 410-MW uprate plan
June 3, 2004
* Vermont Yankee - NRC will use new engineering inspection process
May 19, 2004
* Vermont Yankee - two of twenty cracks found in steam dryer warranted repair
March 26, 2004
GE responds to more MELLLA+ questions from NRC
The non-proprietary version of the response is heavily redacted, even as to parts of NRC's questions. nuclear.com's info nugget BWR - bigger wetwells in Mark III containments minimize pressure during DBA-LOCA contains citation and instructions on downloading the pdf.
February 27, 2004
* BWR - Potential Adverse Flow Effects from Power Uprates
December 8, 2003
* Vermont Yankee - state questions uprate credit sought for containment pressure
December 4, 2003
Power uprates have added 4138 MWe to US n-capacity since 1977; 28 more over next 5 years will add another 1886 MWe
Since May 2003, NRC completed reviews of seven power uprate applications, resulting in a combined increase of approximately 349 megawatts thermal (MWt) or about 116 megawatts electric (MWe). This brings the total number of power uprate applications approved since 1977 to 99, resulting in a combined increase of approximately 12414 Mwt or 4138 MWe (or the equivalent of constructing four power plants) to the nationÕs installed electric generating capacity. NRC staff is currently reviewing four power uprate applications that could, if approved, add an additional 477 Mwt or 159 MWe to the nationÕs electric generating capacity. Furthermore, based on a June 2003 NRC survey of all licensees to obtain information regarding their plans for submitting power uprates over the next 5 years, 28 additional power uprate applications are expected. If approved, these power uprates would result in an increase of about 5659 MWt or about 1886 MWe to the nationÕs electric generating capacity.
[Source: Nils J. Diaz (Chairman, NRC), letter to Sen. George V. Voinovich (Chairman, Subcommittee on Clean Air, Climate Change and Nuclear Safety, Senate Committee on Environment and Public Works), November 25, 2003, ACN ML032900350]
Power uprate reviews - safety is NRC's highest priority
Maintaining safety remains the NRC staffÕs highest priority when conducting power uprate reviews, and the staff will ensure that the goal to maintain safety is not compromised in order to meet timeliness and resource expenditure goals. As more experience is gained, the staff will face challenges to consider the safety significance of any issues that may arise (such as the Quad Cities Unit 2 steam dryer failure, and the Byron and Braidwood ultrasonic flow meter instrumentation reading abnormalities discussed in the Enclosure), the need for modifying its guidance for future reviews of power uprates, and the potential need to revisit prior reviews of power uprates. The staff is staying abreast of operating experience related to power uprates and will maintain a safety focus to ensure that review guidance is updated with experience.
[Source: Nils J. Diaz (Chairman, NRC), letter to Sen. George V. Voinovich (Chairman, Subcommittee on Clean Air, Climate Change and Nuclear Safety, Senate Committee on Environment and Public Works), November 25, 2003, ACN ML032900350]
Operating Experience Related to Power Uprates:
Damage of Steam Dryer at Quad Cities Unit 2
In June 2002, approximately 3 months following implementation of a 17.8-percent EPU, Quad Cities Unit 2 experienced an increase in the moisture content of the steam provided by the reactor to drive the turbine. In July 2002, Exelon (the licensee for Quad Cities Unit 2) shut down the plant, identified cracking in the steam dryer as the cause of the increased moisture content, repaired the steam dryer, and returned the unit to power operation at the EPU power level. The steam dryer does not perform an accident-mitigating role or safety function, but is required to maintain its structural integrity. Approximately 10 months following restart of Quad Cities Unit 2 from an outage to repair the steam dryer, the plant experienced a similar increase in the moisture content of the steam. Based on previous experience with increased moisture content, Exelon shut down the plant and performed inspections of the steam dryer.
Upon inspecting the steam dryer, Exelon identified cracks in several locations of the steam dryer. In both cases, the licensee identified high-cycle fatigue as the cause of the cracking. The staff conducted a special inspection of ExelonÕs activities related to the second incident.
The staffÕs inspection focused on ExelonÕs efforts to identify the cause of the damage and repair the steam dryer. In addition, because Exelon had not completed its root-cause evaluation at the time of the inspection, it committed to keep Quad Cities Unit 2 at pre-EPU power levels until the root-cause evaluation is completed and presented to the NRC staff. On July 25, 2003, Exelon and General Electric Nuclear Energy (GENE) presented their determination of the cause of the cracking, repairs performed on the steam dryer, and planned actions to return the unit to the EPU power level. Following the July 25 meeting, the NRC staff held several additional discussions with Exelon and GENE regarding their analyses. Based on the understanding gained from the inspection, the July 25 meeting with Exelon and GENE, and the discussions following the meeting, the staff had no objections to ExelonÕs plans to return the plant to the authorized EPU power level.
The staff has determined that the steam dryer failure at Quad Cities Unit 2 is not an immediate safety concern. Nevertheless, the staff has continued to monitor closely industryÕs generic response to this failure. GENE issued Services Information Letter (SIL) No. 644, ÒBWR/3 Steam Dryer Failure,Ó on August 21, 2002, to inform its customers of the first steam dryer failure and Supplement 1 to SIL No. 644, ÒBWR Steam Dryer Integrity,Ó on September 5, 2003, to inform its customers of the second steam dryer failure. Both of these documents provided recommendations for monitoring steam dryer performance to ensure that steam dryer degradation is promptly identified. The staff issued Information Notice (IN) 2002-026, ÒFailure of Steam Dryer Cover Plate after a Recent Power Uprate,Ó on September 11, 2002, to inform licensees of the first failure and Supplement 1 to IN 2002-026, ÒAdditional Failure of Steam Dryer after a Recent Power Uprate,Ó on July 21, 2003, to inform licensees of the second failure. In addition, the staff has reviewed GENE SIL No. 644, Supplement 1, and provided comments on the technical evaluation and recommendations contained in the SIL. The staff is planning to meet with stakeholders in November 2003 regarding the SIL and industryÕs overall response to the experience with steam dryer cracking. The staff will consider its regulatory options based on industryÕs generic response.
[Source: "Monthly Status Report On The Licensing Activities And Regulatory Duties Of The United States Nuclear Regulatory Commission, September 2003", enclosure to Nils J. Diaz (Chairman, NRC), letter to Sen. George V. Voinovich (Chairman, Subcommittee on Clean Air, Climate Change and Nuclear Safety, Senate Committee on Environment and Public Works), November 25, 2003, ACN ML032900350]
Operating Experience Related to Power Uprates:
Abnormalities in Ultrasonic Flow Meter Instrumentation Readings
On August 28, 2003, Exelon informed the staff that it was reducing the operating power of Byron Units 1 and 2 by 32 MWe and 22 MWe, respectively. The decision was made following analysis of feedwater flow data derived from the Advanced Measurement and Analysis Group (AMAG) ultrasonic flow meters (UFMs) in use at Byron and Braidwood. Exelon reported that there were signal abnormalities from some of the UFMs, and on Byron 1, there were statistical differences between the total feedwater flow and the sum of the flows from the four individual feedwater lines. On September 1, 2003, the power at Braidwood Unit 2 was reduced for similar reasons. Westinghouse issued Technical Bulletin (TB) 03-6 on September 5, 2003, to inform its customers of the abnormalities experienced at the Byron and Braidwood plants. TB 03-6 also provides recommendations for plants to monitor their instrumentation to identify promptly any such abnormalities at their plants. The staff met with Westinghouse on September 26, 2003, to discuss efforts Westinghouse has taken to identify the cause of these abnormalities.
Westinghouse has not completed its root-cause evaluation of the problems, but currently believes that plant equipment near the instruments could have caused contamination in the signal, thus leading to incorrect readings by the flow meter. Westinghouse has also preliminarily concluded that this issue is limited to Byron and Braidwood. Based on current information, the staff does not believe that this issue poses an immediate safety concern. The staff is closely following this issue for Byron and Braidwood, as well as any implications on instrument installations for MUR power uprates.
[Source: "Monthly Status Report On The Licensing Activities And Regulatory Duties Of The United States Nuclear Regulatory Commission, September 2003", enclosure to Nils J. Diaz (Chairman, NRC), letter to Sen. George V. Voinovich (Chairman, Subcommittee on Clean Air, Climate Change and Nuclear Safety, Senate Committee on Environment and Public Works), November 25, 2003, ACN ML032900350]
September 29, 2003
Palo Verde-2 2.94% uprate approved
NRC issued a power uprate amendment for Palo Verde Unit 2. The amendment supports replacement of the steam generators and subsequent operation at a maximum power level of 3990 MWt, a 2.94 percent increase from the current 3876 MWt. The amendment will be implemented during restart from the fall 2003 refueling outage.
[Ref: NRC Office of EDO, Weekly Information Report, October 3, 2003]
September 29, 2003
Browns Ferry uprates
TVA told NRC it intends to request extended power uprates for all three units at Browns Ferry.
[Ref: NRC Office of EDO, Weekly Information Report, October 3, 2003]
September 26, 2003
Signal contamination of flow measurements used as basis for power uprates
On September 26, 2003, NRC staff met with Westinghouse representatives to discuss their root cause analysis related to the Byron Unit 1 assumed overpower condition regarding crossflow ultrasonic flowmeter (UFM) signal contamination. A portion of the meeting was closed when proprietary information was presented. Special tests indicated frequency contamination that affected the operation of the UFM. The signal contamination was traced to acoustic resonant frequencies in the piping. However, the source of the resonant frequencies is still unknown. Possible sources included feedwater and pumps or other nearby equipment. Westinghouse is still evaluating UFM performance at other plants and plans to respond to the staff questions by the end of October.
The staff advised Westinghouse: (1) to verify the integrity of the information contained in previously-approved topical reports for generic applications of the crossflow UFM; (2) to establish and publish guidelines instructing users how to operate their system; and (3) that future UFM applications for Appendix K power uprates will receive greater scrutiny with respect to signal contamination and assurance that signal contamination is not present. Byron has indicated that they will gather information using UFMs, but will not use the correction factor until the root cause analysis is complete.
[Source: "NRC Meeting with Westinghouse and Exelon on Flowmeter Power Measurements", NRC Office of EDO, Weekly Information Report, October 3, 2003 ENCLOSURE A]
September 24, 2003
Both Plant Hatch units approved for 1.5% power uprates
NRC has approved Plant Hatch's application to increase the allowable generating capacity at both units by 1.5%, mostly due to improvement in the accuracy of feedwater flow measurement. Unit 1 will be rated at 935 MWe; unit 2 will be rated at 950 MWe. Plant management intends to implement the uprates by November.
[Ref: NRC Press Release 03-122, "NRC Approves Power Uprate For Edwin Hatch Units 1 And 2", September 24, 2003]
September 12, 2003
16% power uprate plans
Fermi is seeking power uprate to 3952 MWt, up from the current 3430 MWt. The plant was originally licensed for
3293 MWt. Using the latter number as 100% base, the plant is seeking to go from 104.2% to 120%.
The graph reproduced above shows the various components of the uprates and their contributions to the total.
The plant notes that the uprate will comply with GE's licensing topical report on Constant Pressure Power Uprate, in that there will be:
* No Increase in maximum Rx Dome pressure
* No Increase to maximum licensed core flow
* No increase to MELLLA upper boundary (maximum extended load line limit analysis)
* No change to source term methodology
* No new fuel product line introduction
* No change to fuel cycle length
* No additions to currently licensed operational enhancements
Fermi's presentation slides, released today by NRC, are available here on nuclear.com, as a pdf file.
May 5, 2003 - D.C. Cook's application to increase it's rated power output to 1108 MWe was approved. This represents an 18 MWe uprate. The main basis for the uprate was the increased accuracy of measurements of feedwater flow. The NRC press release notes that the agency's request for public comment published in Federal Register resulted in no public comments.
April 11, 2003 - IP-2 tries Westinghouse SBLOCA secrets for 144.6 MWt Power Uprate - Today, NRC released project manager's report on February 13 meeting at NRC HQ. Here you'll find nuclear.com's review, plus transcription of presentation slides, and local link to meeting report pdf.