Safety evaluation report related to the operation of Watts Bar Nuclear Plant, Units 1 and 2, Docket Nos. 50-390 and 50-391, Tennessee Valley Authority. Supplement number 20, report, February 1, 1996; (https://digital.library.unt.edu/ark:/67531/metadc670823/m1/2/: accessed May 24, 2019), University of North Texas Libraries, Digital Library, digital.library.unt.edu; .