Sliver sample scraping tool (SSST) has been developed for obtaining in situ scrape samples from the pressure tubes of an operating PHWR. The SSST incorporates mainly the scraping tool and hydraulic, pneumatic and mechanical sub-systems. This technique is used remotely to obtain metal samples from a desired axial location from the bore of the pressure tube at 12’O clock position. Initially an oxide layer of about 100 pm thickness is removed from the surface of pressure tube, which is followed by removal of a metal sample.

Two different versions of the tool, namely SSST-I and SSST-II are operable in dry condition of the pressure tube. Hence, de-fuelling, isolation and draining of the channel is required as pre-requisites for obtaining sliver samples from the tube. In order to eliminate these pre­requisites and to obtain samples from wet channels, additional features have been added in SSST-II, which makes the tool operable by the fuelling machine and in un-defuelled channel. Arrangements were made for keeping tool-bits at 12 O’ Clock position and avoiding falling of sample in the magazine of the fuelling machine. The modified tool was designated as WEt Scraping Tool (WEST-I). The average weight of metal sample removed using WEST is 90 mg and the time required for obtaining each sample is approximately 20 minutes.