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Power Ascension Study for Watts-Bar Unit 2
Posted on October 15th, 2015

Tennessee Valley Authority is currently working to bring Unit 2 of the Watts-Bar nuclear power plant on line for operation in 2016.  This Westinghouse pressurized water reactor is the first new build plant to come on line since the opening of the Watts-Bar Unit 1 plant in 1996, and is expected to generate 1,150 megawatts (summer net capability). RSCS has been contracted to perform a Power Ascension Neutron study to support his effort.  This work will establish site-specific neutron correction factors for dosimetry and instrumentation to satisfy the American Nuclear Insurer’s Bulletin 11-02 Neutron Monitoring.   

Pressurized Water Reactors have the highest neutron dose of the industry, and generate a variety of neutron fields. RSCS staff will use Tissue Equivalent Proportional Counters (TEPC) to perform neutron dose equivalent rate measurements at discrete power levels during the initial power ascension process.  These measurements will determine the true neutron dose equivalent rate accounting for the entire neutron energy spectrum.  Quality factors used for each channel of the spectrum will be derived from ICRP-21, 60 and 103 values.  Personnel and electronic dosimeters will also be irradiated on custom ANSI N13-11 phantoms simultaneously with the TEPC measurements at selected locations and compared to the TEPC readings.  This data will be used to calculate the dose equivalent correction factors for the various dosimeters and neutron survey meters that will be used throughout the plant. 

Twenty five years ago, Jay Tarzia and Eric Darois of RSCS performed a neutron characterization for the start-up of the Seabrook Station nuclear power plant while employed at the site.  This was the first time a commercial nuclear power plant self-performed this type of study.  Since then, RSCS has conducted 26 neutron characterization campaigns including containment environments, fuel transfer projects, and ISFSI environments using similar instrumentation and methods.  We are fortunate to have been awarded the first start-up neutron characterization for a new nuclear power plant since that first campaign 25 years ago. 

For more information on the methods used to perform this study, please see Nasser Rashidifard’s presentation to the NECHPS here.  

For more information on Watts-Bar Unit 2, please see here





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