Raman spectroscopy– which works by firing lasers at a target and measuring the resulting molecular vibrations – is one of the most effective techniques for identifying specific chemical compounds, according to Jacobs. But it is rarely used in nuclear decommissioning, where access constraints and high radiation fields can prevent the spectrometer from working at its typical effective range.
However, a team from Jacobs and Kent-based IS Instruments, designed a new type of Raman system which can still detect a weak laser signal when several meters from the target. In addition, the team found a way to mount the Raman probe on to either a remotely operated vehicle or robot arm. This enables the probe to get within two meters of the target and send a signal down an optical cable to the main Raman instrument, safely positioned tens of meters away.
“Standard equipment often cannot detect specific chemical agents, either because it can’t get close enough or because the signals are crowded out by the overall radiation levels,” said Jacobs critical mission solutions international senior vice president Clive White. “This new type of Raman system is an important breakthrough for the nuclear industry because it provides greater certainty about the presence of hazardous materials in high radiation waste facilities, making the materials easier, cheaper and safer to detect.”
Jacobs and UK government agency Innovate UK have provided funding to take the system from proof-of-concept to commercial application. It is now being used to detect uranium and also substances such as kerosene and tri-butyl phosphate, which are used in reprocessing operations and can indicate the presence of plutonium or uranium contamination.
Legacy nuclear facilities sometimes contain significant amounts of poorly unidentified or unknown waste materials, so improved characterisation capability can reduce decommissioning costs and timescales.
Raman technology is also a key feature of a new integrated decommissioning system built by Jacobs, which won a recent UK government-funded innovation competition and will be demonstrated inside highly radioactive former fuel reprocessing facilities at Sellafield later this year.
Outside of the nuclear sector, this advance in Raman technology will be a valuable tool in areas where human access is impossible or problematic, the company adds.