Vermont Yankee reconnects to electrical grid following refueling

first_imgNorthstar Vermont Yankee,Early this morning (May 24, 2010), Vermont Yankee control room operators brought the 650 megawatt nuclear power plant back into service. There was a delay early Sunday morning while reconnecting to the New England power grid when operators noticed that generator readings were different than expected and disconnected from the grid. Plant engineers and technicians traced the problem to an indication circuit in the control room. Once a series of power ascension tests are complete and the output returned to full power, it will bring to a close the plant s 28th refueling and maintenance outage. The outage, which began on April 24th, was based on 18 months of planning and involved more than 6,000 separate tasks including refueling the reactor as well as testing and inspection on virtually every major system in the plant.      Although the plant operated continuously during the last operating cycle — a so-called breaker to breaker run of 531 days — several plant upgrades were implemented to improve long-term reliability. These included replacement of a reactor feed pump motor, sleeving the plant s condenser tubes, and completing the planned cooling tower upgrades including the safety-related section of the west tower.      The testing and/or inspection of major plant components included the main steam isolation valves, various heat exchangers and the reactor internals, including the reactor vessel itself and the steam dryer. Some of these inspections involve specialized remotely controlled cameras that gather high resolution data for engineering analyses.  Of particular interest has been close monitoring of the steam dryer condition and the results continue to demonstrate that the dryer is in excellent shape. Minute flaws in the metal called indications that have been identified in the dryer over the years are not structurally significant, are likely to have been created in the early years of plant operations and have not grown since. The periodic inspection results for the steam dryer and other reactor components are similar to those found at other boiling water reactors and, consistent with industry best practices, the findings are tracked in the plant s ongoing monitoring program.            The refueling of the reactor involved using a precisely positioned fuel handling crane that spans a large pool of water above the reactor. Specialized workers, overseen by senior licensed reactor operators, changed out 116 spent fuel assemblies for new assemblies and rearranged the remaining 252 assemblies in the reactor core. With the fresh fuel assemblies installed, there is a sufficient supply of uranium in the reactor to allow continuous energy output for 18 months.      Entergy Vermont Yankee Site Vice President Mike Colomb said, ”The Entergy Vermont Yankee team and our specialized contract workers conducted this complex work initiative with safety and quality as the highest priorities. The fact that the four-week outage was completed within hours of the target time is a tribute to the planners, engineers, operators and maintenance staff involved in developing the schedule, and preparing for and executing the work.  Special acknowledgement goes to the union craft, including our own staff represented by International Brotherhood of Electrical Workers Local 300 as well as Ironworkers Local 7 in Swanton, Vermont; Teamsters Local 597 in Barre, Vermont; Asbestos Workers Local 6 in Boston, Mass.; Boilermakers Local 29 in North Quincy, Mass.; Carpenters Local 108 in Springfield, Mass.; Laborers Local 473 in Pittsfield, Mass.; Millwright Local 1121 in Allston, Mass.; Operating Engineers Local 98 in East Longmeadow, Mass.; Painters District Council 35 in Springfield, Mass.; Plumbers and Pipefitters Local 104 in Chicopee, Mass.; and Pile Drivers Local 56 in South Boston, Mass. They got the work done. In addition, our security officers, represented by the UGSOA, successfully handled over 800 additional workers accessing the site each day without incident. The excellent workmanship by all involved has prepared this plant for continued safe and reliable operations as a vital supplier to Vermont s electricity consumers, he said.      During the outage, the plant also connected to the new VELCO electrical transmission substation to the north of the plant which is designed to improve reliability of the regional electrical grid.      The plant staff will now take several days to achieve full power to accommodate tests and monitoring of plant systems during the power ascension. That work will be coordinated with ISO-New England, the region s electrical dispatcher.       The plant supplies approximately one third of the state of Vermont s electrical needs.Source: Vermont Yankee. 5.24.2010last_img