How to Make Radiation Mapping Safer and More Reliable

Radiation mapping is a crucial exercise in the nuclear industry but traditional approaches are challenging. Spot’s autonomy, agility, and ability to perform in high-radiation environments make it a reliable solution.

6 minute read

Understanding how much radiation is present—and where—is essential for both the ongoing safe operation and eventual decommissioning of nuclear power plants. These goals are met using several methods of radiation mapping depending on specific needs. “Radiological protection surveys” provide workers with a briefing before entering a potentially radioactive work site. 3D gamma imaging provides a detailed digital model of an environment to highlight where the sources of radiation are, so that engineers and workers can quickly identify leaks and validate the effectiveness of clean-up procedures.

The Challenges of Radiation Mapping

Traditionally, nuclear facilities have used a mix of approaches to conduct radiation mapping—including manual surveys with handheld devices, continuous monitoring using fixed sensors and air sampling systems, and remote investigation with traditional robotics. These methods all pose challenges based on a few factors:

  • Health and safety considerations
  • Lack of flexibility to monitor emerging issues and analysis of changes over time 
  • Limited availability of trained personnel
  • High costs due to downtime

Worker health is always a top concern. Ensuring that people who need to do a job inside of a radiologically-controlled area receive the lowest dose possible requires, paradoxically, that some people in the plant will absorb a higher radiation dose. This is because executing a radiation survey—necessary for ensuring safe working conditions—requires people to take measurements of radiation levels at critical areas around the facility, absorbing a controlled amount of radiation in the process. Safety standards dictate a maximum allowable dosage of exposure, which limits both the frequency and duration of these surveys, while some areas can’t be entered at all without lengthy—and costly—shutdowns.

Fixed sensors and air sampling systems installed at predetermined locations are frequently used to conduct real-time radiation monitoring on a permanent or temporary basis. Limited geographical range for each means a few critical areas of the plant might be missed despite best efforts at overlapping coverage. Access is often constrained around particular pieces of equipment that might be sources of radiation. Under such conditions, fixed sensors become more of an alert mechanism, registering radiation only when it reaches zones close enough to the sensors. In addition, many fixed sensors are calibrated to measure only certain types of radiation, and as a result are exclusively utilized for alerting and long-term monitoring purposes. They cannot provide granular information for diagnosing unusual conditions or performing surveys.

Radiation protection surveys provide a more accurate understanding of the levels, types, and geography of radiation within an area. These surveys frequently require people to use radiation detectors and air sampling devices, as well as surface swabbing to detect loose contamination. A similar, more intensive process applies to decommissioning of nuclear power plants. Project managers use radiation mapping to learn where the most hazardous sources are located.

Teleoperated drones and wheeled robots offer some benefits for remotely inspecting high radiation areas, but both have some limitations for navigating environments normally traversed by people. Drones have difficulties loitering in a hazardous area for sufficient time to diagnose emergent issues, while wheeled or tracked robots struggle to navigate stairs or unfamiliar environments they might encounter in decades-old facilities. Additionally, most of them also have no autonomous functionality, which means plant staff must guide them throughout the duration of every inspection.

Additionally, trained personnel have limited availability and are typically expensive to deploy, so most plants conduct traditional radiation mapping exclusively on an as-needed basis. When radiation mapping exercises are conducted infrequently, or on-demand at inconsistent intervals, critical data points may be missed in the long-term trend analysis, which means plant managers often need to rely on alternative instrumentation to validate that their systems are operating as they should at all times.

Autonomous radiation mapping solutions like Spot can solve these challenges.

A Dynamic Approach to Radiation Detection

Spot is an agile mobile robot that can carry a variety of radiation detection payloads and conduct autonomous radiation mapping operations.

Its advantages in nuclear power plants settings include:

Ability to withstand large amounts of radiation: Spot has been tested in high-radiation environments and has been found to operate successfully without loss of functionality in gamma fields in excess of 250 rem per hour, and a total absorbed gamma dose in excess of 420 rem. This is great news for deployment in unknown or potentially high-radiation environments as it dramatically minimizes human radiation exposure and can help with both minimizing preemptive shutdowns and ALARA (as low as reasonably achievable).

More frequent of radiation surveys: Spot can live onsite within radiation zones and operate autonomously—or be operated remotely—for regular operations. In either instance, operators can choose the frequency with which they want to conduct radiation mapping exercises without budget and personnel challenges limiting their capabilities.

Flexible sensing platform: Radiation mapping involves measuring a variety of radiation types. Spot can carry gamma ray sensors, personal dosimeters and it helps with neutron detection and alpha inspection with pancake sensors. Radiation detection payloads integrate with Spot’s onboard application programming interface (API) to relay mapping data back to the user, as well as provide repeatable mission summaries. Spot can also be fitted with 3D mapping, gamma camera, and gamma spectrography systems to deliver enhanced radiation visualizations and isotope identification for nuclear decommissioning, cleanup projects, and public safety use cases such as retrieving orphaned sources.

Agile mobility: Because Spot travels to the source of radiation as opposed to a fixed sensor that waits for radiation to travel to it, the robot provides greater coverage. Spot’s ability to navigate stairs and other unfamiliar environments helps it conduct radiation mapping measurements in all areas, including difficult-to-reach ones.

An additional pair of eyes: Spot live-streams data from nuclear power plants without the need to deploy people onsite. At the same time, site operators can “see” the situation live and troubleshoot problems in real time. Workers make decisions based on accurate information.

Platform for advanced technologies: Operators can extend Spot’s capabilities by adding on advanced computer vision models and AI and machine learning algorithms to study historical behavior and see when radiation mapping alerts them about problems down the pike. Spot allows for a proactive—instead of reactive—approach to ongoing nuclear power plant management and empowers operators to do more with the data they gather.

Traditional methods of radiation mapping are buckling under a variety of constraints. Spot’s autonomy, agility, and ability to function as designed even in hazardous environments makes it an elegant solution for radiation mapping and other nuclear power plant management issues.

To learn more about how Spot is being used in the real-world, watch our on-demand panel discussion, Spot in Nuclear Environments.

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