Improved Zr-2.5NB pressure tubing for future HW reactors

The diametral expansion of pressure tubes in CANDU reactors due to irradiation creep is an important parameter that affects the critical-heat-flux and is therefore a reactor life-limiting property. There is considerable variability in diametral strain rates between tubes in different reactors that can be associated with manufacturing practice and their microstructure. As aging reactors are being refurbished and fuel channels are being replaced there is an opportunity to take advantage of our prior experience and select manufacturing parameters that lead to optimised pressure tube performance. Statistical analysis has been used to assess the diametral creep performance as a function of manufacturing variables and microstructure parameters. (author)