Decontamination / Decomissioning Techniques
Effective Rotary Polishing
In certain circumstances the use of high or ultra-high pressure water jetting is either not suitable or indeed not advisable. The ability to remotely dry descale and polish tubes and pipelines within the nuclear power sector is rare yet it is increasingly being recognized as an ideal way to remove low level waste to free release.
The tubes and pipelines on a French nuclear power station had to be cleaned using a dry system and Tube Tech’s methods were recommended to them by a UK nuclear power station. A fast and safe system, using multiple, extendable rotary drills with polishing heads in tandem with mechanical percussion and air blast provided a solution to what the power station believed was a challenging situation. Tube Tech cleaned up to 40 tubes per day with this dry procedure. The polishing action of the drill heads meant there was no necessity for follow-up shot blasting. Shot blasting can also be counterproductive as it is known to erode and etch the first few meters of the tubes’ internal surfaces. This can detrimentally provide a key for deposits and accelerate build-up for the future.
“There were many advantages to using our own unique drilling system not least that we reduced downtime substantially,” said Mike Watson, Managing and Technical Director of Tube Tech. “Logistically we had to maintain a constant supply of spare cleaning tips in order to adapt to changes in deposit characteristics. Our team worked so quickly that we were manufacturing tips as fast as we were using them. Each day new supplies were flown or driven to the France from the UK.”
Decommissioning of nuclear power stations has to be carried out safely. Most of us would prefer it was carried out quickly as since reliable cost estimates are extremely difficult to make so any time saving will in turn provide a cost saving. As we enter an era of new nuclear power station design and build it is crucial that advances in decommissioning and decontamination are recognized and acknowledged so that positive practices can be understood and improved upon as the nuclear new build era continues.