Laser cutting technology

The purpose of the LD-SAFE

The purpose of the LD-SAFE project is to demonstrate that both the in-air and underwater laser cutting technologies are effectively operational for the dismantling of the most challenging components of power nuclear reactors (RPV and RVI) and that, for this application, the laser cutting technique:

Is as safe as the best cutting techniques currently used, even safer for the workers and environment.
Does not add any new constraints.
Is more cost effective to dismantle the challenging power reactor components.
Is simpler to implement on site and better suited to the complex dismantling of components such as reactor internals.

The ambitions of the LD-SAFE project are to remove the last technical, safety and economic barriers that prevent the replacement of conventional cutting techniques for the dismantling of power nuclear reactor by the laser cutting technology. At the end of LD-SAFE, the suitability of the laser cutting technology to address the challenges of the dismantling power nuclear reactor and its capability to improve these projects in respect of safety, radioactive waste, time and cost will be confirmed on the basis of the demonstrators proposed by the project.

ADVANTAGES

From the point of view of technical criteria (important safety and economic aspects are presented below in this section), laser cutting is a promising alternative.

Laser is widely used in the industry for cutting or welding works, not yet for the decommissioning of industrial nuclear facilities. High power lasers are now commercially available off the shelf and at reasonable prices.

Excellent cutting performance on metallic/ceramic material with a cutting capability of up to 200mm in thickness.
Cleaner than most of other thermal techniques, especially in respect of dust & fumes.
Technique minimizing slag production (secondary waste production).
Has been paired with a selection of manipulators for various applications in nuclear decommissioning
Proven performance and long life in highly radioactive environments.
Safe for the operation and maintenance workers (reliable remotely operated technology).

LASER CUTTING VS FUEL CYCLE

Differences between the dismantling of power nuclear reactor and fuel cycle or research facilities

Technically speaking, because power nuclear reactors have bigger and thicker components that are harder to cut than those of fuel cycle facilities and, while most of the nuclear dismantling is carried out in air, dismantling power nuclear reactors may require both in air and underwater remote cutting operations.
In respect of safety, because unlike for fuel cycle facilities the components are not isolated in cells and because the radiological impact must be regarded for much larger areas where workers are operating. Also, the radioactive source term for power reactor dismantling is different (activation of the material).
Regarding the cost and time, with quantitatively greater impacts of the choice of cutting technology and because, while fuel cycle facilities tend to be highly specific, operators of power nuclear reactor need repeatability to dismantle their fleet.

CHALLENGES

Nuclear Decommissioning Market is expanding

New decommissioning challenges are arising

Increasing number of reactors to be decommissioned safely.
Fuel cycle facilities with high levels of hazard to be decreased.
Reactors damaged by nuclear accidents to be managed.

Cutting technologies must be (re-)invented to

Be deployed remotely where human access is impossible.
Be robust, reliable, flexible and safety compliant.
Improve decommissioning projects in terms of cost and time.
Meet the highest safety standards and guarantee the protection of the people and of the environment.

Remote cutting is a mandatory step for any decommissioning project with very high levels of radioactivity.

SAFETY

From the point of view of technical criteria (important safety and economic aspects are presented below in this section), laser cutting is a promising alternative.

In proposing the replacement of conventional cutting techniques by the laser cutting technology, the main driver of the LD-SAFE project is first and foremost to propose an alternative for the segmentation of RPV and internals which is safe and does not add any new constraints.

To this end, the progress proposed by the project includes the delivery of a Generic Safety Assessment prepared as per the international good practices, independently reviewed by a TSO member of ETSON and including all the relevant nuclear safety topics as per the up-to-date standards such as Radiation Protection, Fire safety, Ventilation and Confinement and Human & Organizational Factors.

The set of KPI 6 are focusing on the main safety aspects to demonstrate that the laser cutting technology is not to be compared with the thermal cutting techniques currently used, as it is much safer.

The protection of the workers and of the environment is an integral part of nuclear safety (see above), but one aspect in this respect which make the laser cutting safer than the techniques currently used is the fact that 100% of the works can be carried out remotely, thanks to the absence of maintenance carried out by workers in controlled area. Demonstration that the laser cutting technique is safe for the workers and the environment is proposed within the project of the basis of a dedicated Technology Qualification Plan.

It is anticipated that the acceptance of the laser cutting technology would allow further reducing human hands-on activities, with is a key lever of improvement of the safety of the workers on nuclear dismantling sites. Indeed, the benefits of the laser cutting technology should allow considering carrying out more works in remote operation.

OUTLOOK AND IMPACT

Laser cutting is not yet considered for all cases of dismantling application

Laser cutting is not yet considered for all cases of dismantling application, such as commercial reactors, because of a lack of past experiences and because the stakeholders need to be reassured as they have remaining safety concerns related to its implementation.

To bring the benefits of this already mature technology fo further fields of applications, the R&D needs to focus on the two main topics in terms of safety, people and environment protection:

The non harmlessness of the laser beam on the surroundings due to the residual light and reflexions.
The confinement of the cutting environment due to the gases and aerosols generated.

Laser cutting technology

The purpose of the LD-SAFE

Differences between the dismantling of power nuclear reactor and fuel cycle or research facilities

Laser cutting is not yet considered for all cases of dismantling application

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