DECONTAMINATION & DECOMMISSIONING | LASER ABLATION
Laser ablation: becoming a mainstay in DECON
Laser ablation systems designed for cleaning, de-coating and decontamination can save the nuclear industry time and minimise costs. By Timothy Niemeier
HIGH POWER LASER ABLATION SYSTEMS designed for industrial decontamination applications are proving effective at nuclear sites around the world. Disaster sites Chernobyl and Fukushima have successfully evaluated this technology to improve worker safety and eliminate radiation efficiently. Systems have come a long way since 2006, when the
VP Adapt Laser Systems Timothy Niemeier
Electric Power Research Institute (EPRI) documented the successful testing of laser ablation to remove radioactive coatings, surface contaminants and oxides in power plant applications. Today, these industrial laser systems are commercially
available, powerful and field-ready to support the global nuclear industry, in power generation as well as military and medical applications. They have features designed to optimise the benefits of a unique method that uses only focused light to quickly remove fixed low-level contamination from 80% of metallic nuclear waste that has only surface contamination.
Process improvements needed Commonly used processes for removing low-level contamination include grit blasting, water blasting, CO2 pellet blasting, chemical cleaning and power tool grinding. While these methods can be effective, they typically produce a significant volume of mixed hazardous waste which is difficult and time consuming to collect, with high cost of disposal. Operator safety is another significant concern with
traditional methods. Concerns are excessive dose rates, repetitive stress, risk of serious injuries, excessive noise and the inhalation of hazardous airborne contaminants. Abrasive grit and CO2
blasting are generally not suitable
for use near other operations. During set-up, operation, and clean-up, on-going plant operations staff have limited access to work areas. Abrasive blasting risks damage to adjacent surfaces
and may remove excess base metal. Often costly custom tooling becomes unusable due to lack of safe, damage-free decontamination technologies. These abrasive media- based processes are time consuming and costly due to the large amounts of hazardous waste material that must be contained, collected and removed. While traditional decontamination methods can be
useful, commercially available laser-light-based processes have been tested and proven to be a cost-effective solution for a growing number of nuclear sites and industry service providers worldwide.
38 | March 2022 |
www.neimagazine.com
Advanced laser ablation Laser ablation is a non-abrasive cleaning method that uses no consumable media, chemicals or gases. It may be used in close proximity to other activities, near sensitive controls and on or near operating equipment. Typical systems consist of a portable laser source with a fibre optic beam delivery to a hand-held or robot-mounted laser end-effector. Ablated materials are collected at the target surface by a laser fume extractor, with multi-stage filtering, thereby preventing release. The capabilites and benefits for laser ablation include:
● Removal of contaminated coatings, oxides and rust and hydocarbons
● Significantly minimising the volume of radwaste ● Radwaste reduced to a less costly waste disposal classification
● Dose risk reduction from potential contamination sources ● Recovery of costly tooling ● Recycling of valuable metals that would otherwise be costly radwaste
● De-painting of critical weld seams for NDT
Decontamination of dump trucks In Oak Ridge, Tennessee, laser ablation proved effective in reducing time required, worker stress and radwaste. The application involved the decontamination of carbon-steel from large dump truck beds used to haul contaminated materials from sites around the decommissioning of K-25 in Oak Ridge. Contamination comprised varying isotopes, primarily U-238. The contaminants were largely Beta emitters, found in conjunction with low Alpha contamination. Testing was conducted by Adapt Laser and Philotechnics
Ltd, which processes and transports radwaste. The latter provides radioactive and mixed waste management solutions, including decontamination and decommissioning services, radiological health physics staff augmentation, health and safety plan development, and radiological qualification training. Adapt and Philotechnics worked together to prove laser ablation as a viable source for removing radiological contamination with potential time savings. The current decontamination method involved manual grinding of contaminated metal using large heavy hand- held power tools. This process required 200-man hours and two technicians to complete a single dump truck bed. The laser ablation process only required 7% of that time — one technician for four hours — to achieve similar results.
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45
