Annual report, FY 1979 Spent fuel and fuel pool component integrity.

Abstract

•• 2) Spent Fuel Examinations 3) Fuel Pool Component Examinations 4) Corrosion Mechanism Assessments. This report summarizes activities conducted under the Program at Pacific Northwest Laboratory (PNL) during FY 1979 and updates information regarding spent fuel and fuel pool component behavior in pool storage.

Examination of stainless steel-clad Connecticut Yankee fuel assembly S004 after storage in borated water

“…However, fuel rods in those assemblies were not characterized as well as some in S004. As of 1979, the highest burnups for fuel assemblies with stainless steel-clad fuel rods discharged from domestic and foreign commercial reactors were 37,500 MWd/MTU (3,240 GJ/kgU) (batch average) and 32,000 MWd/MTU (3,765 GJ/kgU), respectively (Johnson 1980). Some domestic fuel with batch average burnups to the former level were discharged during this 1972-1976 period.…”

“…The S004 assembly contains stainless steel-clad fuel rods, 20 of which were well characterized prior to irradiation. The incentives for investigation such a fuel assembly were: 1) of the nuclear fuel stored in the United States as of mid-1979, approximately 7%, nearly 1500 fuel assemblies, contained stainless steel-clad fuel (Johnson 1980); and 2) stainless steel is known to show susceptibility to stress-corrosion cracking in some environments and in certain metallurgical conditions. Some standard commercial fuel assemblies stored at the Connecticut Yankes spent fuel pool had higher burnups (i.e., irradiation exposures to 36,800 MWd/MTU or 3180 GJ/kgU) or longer times (to 10 yr versus 5 yr for S004) in pool storage.…”

Examination of Zircaloy-clad spent fuel after extended pool storage

“…An extensive search for candidate fuels was conducted (Johnson et al 1980). Fuel rods from commercial reactors of current design generally lack the detailed information regarding the condition of the cladding after discharge, and they have been stored for relatively short periods «10 yr).…”

“…Fuel bundle 0551 contains the world's oldest pool-stored Zircaloy-clad fuel rods. This bundle was discharged from the reactor in 1959, and the (a) Parker 1978;Hunt, Wood, and Bain 1979;Peehs et al 1978;Huppert and Zimmerman 1977;Warner 1977;Flowers 1977;Johnson et al 1980;Johnson 1977;Vesterlund and Olsson 1978;Mayman 1978;Huppert 1978. (b) Lynam 1963Lynam 1964;Henke 1966;Rubin and Lynam 1966;Larson 1960;Rubin 1961(a); Rubin 1961(b);Sphar 1962;Lynam 1961;Lynam 1962. rods included in this examination had been stored in deionized water for nearly 21 yr when they were reexamined.…”

“…(a) Parker 1978;Hunt, Wood, and Bain 1979;Peehs et al 1978;Huppert and Zimmerman 1977;Warner 1977;Flowers 1977;Johnson et al 1980;Johnson 1977;Vesterlund and Olsson 1978;Mayman 1978;Huppert 1978. (Johnson 1977;Uhlig 1967) or concentration of aggressive species such as chlorides (Johnson 1977;Carlson 1963).…”