Our client was appointed to create a specialist remote 3D laser scanning method for use on a contaminated site at a former nuclear facility. The main objective of the project was to make a scan of the building to internally survey the main cell to enable a 3D model of the internal cell configuration to be generated. This would allow the company to upgrade, and process used fuel offsite safely.
Due to the implications of working on a nuclear site and in order to meet the requirements of the project under strict environmental and personnel constraints, the scan needed to be carried out remotely which required taking an unusual approach to 3D scanning as conventional techniques of scanning would be unsuitable. It was essential that the building’s extract ventilation, air monitors and cell extract ventilation was monitored to detect failure, in which case work would need to stop immediately.
The project was challenging to achieve a method of taking the scan remotely through the roof port to mitigate the risk caused by background radiation. The area was designated as having a moderate level of contamination and low level of radiation. As a consequence, it was a pre-requisite that all personnel carrying out the activities had to be classified workers with electronic personal dosimeters. This would allow for the detection and display of the continued dose rate and cumulative dose of the penetrating and no-penetrating radiation.
To ensure the 3D scan could be made safely and successfully, they had to develop a technique that would allow the scan to be carried out by classified workers without the necessity of having prior experience in the field. To meet these criteria, the team were required to develop a completely novel method of scanning that would allow the access site to be heavily monitored for contamination and be easily carried out under the supervision of the engineers.
A PVC area was set up at the roof port of the cell, with an Activity in Air Monitor (AAM) located within the barriered area and a second AAM was positioned outside the area. Each AAM was set to alarm at 5DACh alpha and 1 DACh beta. This allowed the team to monitor the conditions within and outside of the cell to detect radioactive aerosol particles provide alarm signals should the concentrations exceed a multiple of the derived air concentration (DAC) of the radionuclide of concern in a set amount of time. The cell and south stack extract ventilation was in operation and remained so for the duration of the work being carried out.
The equipment set-up above the roof port consisted of an inverted tripod mounted on the Cell 10 roof valve. The legs of the tripod were located on the valve centralised over the roof port to allow for easy and controlled access. Sectional deployment poles were mounted onto the tripod with a cell posting bag to be sealed to the pole above the scanner head attachment and a lay flat taped on and concertinaed over the deployment pole.
The scanning process was developed to be easy for classified personnel to deploy for health and safety reasons. Once the posting bag was secured to the pole, the power button on the 3D laser scanner was pressed to initiate the scanning process. The scanner was equipped with a sufficient time delay to allow for the deployment into the cell before scanning would commence.
Our client’s involvement on this project has resulted in the development of a novel method of specialist 3D scanning which could be deployed in the future in areas of environmental constraint such as contaminants and pollution. The work undertaken by the team has resulted in a clear advancement of industry specific knowledge.
Lauren Brindle
