Safety Improvement and Cost Savings for Underwater Inspections by Using Submersible Robotics - MTA-MA-030

Administrative Items
Date	12/14/2021
Functional Area Where Benefits Will Be Realized	Maintenance Operations
Reference Implementation Guidance	Example usage of submersible robotics discussed in Data Diver Surveys for TVA and Duke Energy (EPRI Technical Report 3002019362) For additional implementation guidance, please contact EPRI.
Industry SME	EPRI – Steve Lopez Contact: NuclearPlantMod@epri.com
Previous Implementation	Please contact EPRI for implementation examples and contacts.
Implementation Enablers	N/A
SWEEP Score	Cost – Level 3 – Implementation cost is less than $1 million for a facility that has no prior submersible robotics experience. Savings – Level 1 – Savings are less than $1 million per year. The biggest saving comes from avoiding using contracted divers. Payback – Level 3 – The payback period is expected to be less than one year. Licensing Readiness – Level 3 – This technology has already been implemented at nuclear power plants and does not require industry regulatory changes. Technical Readiness – Level 3 – The technology is already in use at commercial nuclear sites. Implementation Proficiency – Level 2 – The technology requires some proficiency with integrating technology. External support may be required to train personnel on how to operate submersible robotics.
Applicability	All reactor types All geographic regions
Keywords	Submersible robotics, Cleaning, Object Retrieval, Remote Operated Vehicle (ROV), remote inspections, intake structures
Business Case Analysis Cross-Reference	N/A

Description

Nuclear power plants periodically access submerged locations such as water intake structures to perform inspections, routine cleaning maintenance, and debris removal. Divers typically accomplish these tasks via manual human interaction. Planning underwater work in a water intake structure is a significant undertaking from a time and cost perspective, given the potential hazards associated with the work (e.g., inadvertent actuation of plant equipment while a diver is in the water). Additionally, visibility underwater is poor, and divers wear heavy rubber dry‑suits for protection, limiting productivity and capability to execute tasks.

Submersible robotics offer an alternative to using divers for underwater inspections. Submersible robotics equipped with a robotic arm can also clean small areas and retrieve small objects. Submersible robotics are operated remotely typically via tether and can be equipped with various tools to support navigation, inspection, and maintenance tasks. Video and sonar attachments to the submersible robotics can be used to assist operators in navigating turbid waters and collecting high‑quality inspection data. Maneuvering a submersible robot using sonar for navigation requires a trained operator.

This technology enables improved efficiency and personnel safety for inspection and maintenance of submerged objects and areas, increased flexibility for executing work, and higher‑quality data collected during the inspections.

Intake structure inspections are only one potential application for submersible robotics. Another potential use case (not specifically covered in this MTA) is weld inspection/repair in spent fuel pools and fuel transfer canals, which would reduce diver exposure to radiation and allow work outside of outage windows. Note that once a submersible robot is used in a contaminated area, it is typically not used in non‑contaminated locations.

Benefits

Benefits Estimate

Level 1 – Savings are less than $1 million per year. Savings are realized by avoiding dive costs.

Benefits Description

• Reduced risk to divers. Diving in an industrial environment is hazardous. By replacing divers with a submersible robot where feasible, personnel (diver) risk and plant effort to support the dive is greatly reduced.
• Reduced cost for diving‑related activities. The all‑in cost of a submersible robot is low relative to the cost of contracting divers – potentially less than the annual cost of divers. Submersible robotics cannot currently replace all tasks performed by divers. Therefore, savings are limited to diver tasks that can be replaced.
• Improved flexibility to address emergent issues. Reduced planning time and operational limitations for diver safety may allow a submersible to be deployed more quickly, particularly if the utility has its own submersible robotic equipment and trained operators.
• Increased inspection quality with water‑proof camera and inspection tools in difficult to access areas. Submersible robotics are smaller and more maneuverable than a diver and can work in low‑clearance areas, providing an opportunity for more data and higher‑quality data from inspections in some cases.

Costs and Schedule

Cost

Level 3 – Implementation cost is less than $1 million to implement submersible robotics for a facility with no prior submersible robotic experience. Increasing the complexity of submersible robotics usage to realize additional benefits (e.g., implementing data governance and analytics) will increase the implementation cost.

Schedule

Less than six months. Submersible robotics are relatively easy to obtain. The majority of implementation time will be spent training operators on the use of the technology, which may require an external service provider.

Scope Context

Per site.

Risks

Submersible robotics are typically tethered to a handheld console the operator is using to pilot the submersible robot. However, the submersible may become stuck or inoperable when performing a task. Therefore, facilities should ensure that a retrieval plan is in place should such event occur.