TVA moving from the big stuff to the small stuff in Watts Bar 2 project

The Tennessee Valley Authority on April 11 reported that work on Unit 2 at the Watts Bar Nuclear Plant continues to meet targets for safety, quality, cost and schedule as the project prepares to transition from construction to completing and releasing systems for testing.

TVA issued its third quarterly update on Watts Bar 2 (WBN2) progress since the TVA board of directors last year approved continuation of the construction project under a revised Estimate to Complete (ETC) by December 2015. There is a projected total cost of $4bn to $4.5bn for this work. The quartertly update released April 11 covers November 2012 through January 2013.               

“The update shows that productivity is aligning with the schedule and the pace of installing commodities, such as miscellaneous steel, electrical conduit, large valves and tubing, is on track to support completion milestones,” said Mike Skaggs, TVA senior vice president for Nuclear Construction.

Most of the commodities remaining to be installed include cables, small valves, instruments, and associated pipes and tubing that make up the operating systems for the unit. As a result, there is now a transition from bulk construction activities to completing systems and releasing them for testing. Skaggs said work on several systems is being accelerated to find and prevent potential problems early in the completion and testing processes so they won’t impede progress later.

“We have not identified any new short-term issues that compromise project completion, but we recognize there are challenges to completing this unit, with regulatory and licensing issues being our primary challenges,” said Skaggs.

When complete, Watts Bar 2 in Tennessee is expected to generate about 1,100 MW, enough electricity to supply about 650,000 Tennessee Valley homes.

Changes being made due to lessons from Fukushima

One area of work lately is to draw lessons from the 2011 Fukushima nuclear accident in Japan, when a massive ocean wave caused by an offshore earthquake swamped backup generators in low-lying areas, cutting power to the nuclear reactors on a bluff above the floodwaters. The Nuclear Regulatory Commission (NRC) is requiring U.S. nuclear operators to make changes due to that accident.

“The regulatory impacts of Fukushima, including related seismic and hydrology issues, will be significant for WBN2,” said the quarterly report. “The project has submitted the required documents to the NRC with near-term submittals due for flood impacts and FLEX strategies-an approach that uses a diverse and flexible set of portable equipment and emergency plans to increase protection against events that go beyond a plant design basis. The final regulatory framework for the industry response has not yet been developed and guidance, especially for seismic and hydrology, is potentially months away. In the interim, the project team has developed a number of alternatives based on the information currently available. However, until the framework is completed by the NRC, the risk due to the Fukushima event remains at the same level as in the ETC.”

Plans and detailed schedules have been developed by teaming with several organizations within TVA and numerous contractors to facilitate completing the large volume of work. Activities underway to address the events at Fukushima include:

  • The concrete sections of two dams have been analyzed, and engineering is in the process of determining necessary modifications.
  • The engineering design for the permanent fix of the temporary flood barriers is approximately 30% complete for the four affected dams. Eighteen additional dams are being analyzed. Walk downs have been completed on all eighteen, geotechnical exploration is in progress on eleven dams, the development of the new seismic hazard curves and multi-dam locations have been contracted, and the nuclear-specific cases defined for all eighteen dams.
  • The design engineering for the FLEX Equipment Building is approximately 40% complete and the diesel pumps and portable generators (both large and small) have been procured. Designs for the physical installations of the FLEX equipment are in progress.
  • The preliminary design for the spent fuel pool level instrumentation is complete and the procurement of the instrumentation is under way.
  • Hardening of the existing condensate storage tank was not possible, so the design for a replacement beyond design basis event tank is under way.
  • The vendor for the Seismic Probabilistic Risk Assessment has been chosen.
  • Design engineering and procurement of new communications equipment is in progress.
About Barry Cassell 20414 Articles
Barry Cassell is Chief Analyst for GenerationHub covering coal and emission controls issues, projects and policy. He has covered the coal and power generation industry for more than 24 years, beginning in November 2011 at GenerationHub and prior to that as editor of SNL Energy’s Coal Report. He was formerly with Coal Outlook for 15 years as the publication’s editor and contributing writer, and prior to that he was editor of Coal & Synfuels Technology and associate editor of The Energy Report. He has a bachelor’s degree from Central Michigan University.