New scanner will boost safety at Lithuanian nuclear plant

New ultrasonic equipment to inspect the integrity of welds in pipework is helping to improve safety at Ignalina nuclear power station in Lithuania. Phoenix Inspection Systems, the NDT equipment specialist, has collaborated with the NDT Technology team at Mitsui Babcock to develop and qualify a new type of pipe scanner. The scanner will enable the rapid and reliable detection of stress corrosion cracking (SCC) in the primary coolant pipework of the two RBMK reactors – Soviet-designed pressurised water reactors - at Ignalina. The work has been funded by the UK government’s Nuclear Safety Programme which provides safety assistance projects to organisations in Central and Eastern European and former Soviet Union countries. The scanner will be used to replace the manual ultrasonic inspections of stainless steel welds, which are prone to stress corrosion cracking. It is part of a semi-automated inspection system which provides two main benefits compared to manual UT – greater reliability and quicker inspections. Fraser Hardie, NDT Group Leader with Mitsui Babcock in Renfrew, near Glasgow, explained: “Working with Phoenix, we have developed a new system that is designed to operate with as little as 50mm radial clearance from the pipe surface. This unique pipe scanner is rapid to install and reliable to use and has provided an excellent solution to a major problem. "Faster inspections mean that the inspection personnel are less exposed to radiation and outage programmes are easier to achieve. The enhanced reliability makes a significant contribution to improving nuclear safety.” The new semi-automatic scanner holds up to six of Phoenix’s automatic inspection probes that can be set at varying degrees of axial separation for scanning different material thicknesses. Once clamped on to the pipe, the scanner can carry out a fully encoded 360 degree scan of a 325mm diameter weld in about one minute. Dave Smith of Phoenix Inspection Systems said: “One of the aims of the design was to minimise the amount of time operators needed to spend in a radioactive environment. The scanner can be set up in minutes and is quick and easy to use. It is linked, using an umbilical cable up to 60m long, to a monitoring station outside the restricted area, where the results can be interpreted both on and off line, at a time convenient to the inspection process. “The new system certainly represents a major improvement in safety standards, both for the operators themselves and in terms of the quality and repeatability of inspections.” This latest pipe scanner is one of a number of special scanners which Mitsui Babcock has asked Phoenix to develop for difficult inspection conditions over the last few years. For further details about Phoenix scanners contact Paul Ryan on +44 (0)1925 826000