Above: Retrieving a dropped cell phone from a 6”-ID plastic-lined drainpipe


FOREIGN MATERIALS POSE A SIGNIFICANT risk to both nuclear power plant safety and profitability. This issue has plagued the industry for decades.

Whether it is a small object like a pen or a loose part that has degraded over time, foreign materials can trigger dangerous conditions such as damage to fuel cladding, degradation of heat-transfer equipment, higher levels of contamination and increased radiation exposure.

The response has been foreign material exclusion (FME) programmes, key initiatives supported by the Institute of Nuclear Power Operations (INPO) that provide training, and offer work planning techniques and implementing guidelines to help minimise the risk posed by FME. In addition a staggering amount of effort goes into drop prevention at nuclear power plants across the globe.

There are many ways to help secure potential foreign materials and to protect employees from becoming contributory factors, but a huge amount of damage can be done just with relatively small things. Steam generators are a prime example of components with significant issues caused by loose parts. These are high-pressure, high- velocity, high-value systems in which loose parts can do a tremendous amount of damage.

Foreign materials frequently end up in the steam lines that feed into heat exchangers, turbine or the boiler. Everything from pieces of the turbine to hard hats have been discovered in these areas (among many others).

If loose parts or other foreign materials get into the process and make it through filters and valves, they can wreak havoc, and if a nuclear plant has to shut down, the economic impact is huge.

Even with the tremendous effort put towards prevention, loose parts still remain a concern. No matter if they are degraded plant components, or tools inadvertently dropped during routine maintenance or repair, foreign materials can quickly create schedule delays for the utility and cost overruns for vendors.

In the past, plants would suffer unplanned downtime to retrieve loose parts and foreign materials or be forced to live with the risk. But what if that risk could be quickly and efficiently removed instead of just mitigating it?

That is exactly the type of all-in-one solution that a our tool, JAWS 2.0TM, offers. This industrial retrieval tool features a submersible, aircraft-grade aluminium body with stainless steel jaws that open to 2.75 inches (70mm). It is highly specialised and designed to fit through a 1.5” (37mm)- diameter access hole, while navigating a 4”-diameter, 90-degree elbow. In addition to its compact size, the motorised tool is waterproof to 30m and has an integrated high-definition HDTV camera with long-life LED lamps to allow users the visibility that is necessary for successful retrievals.

One maintenance manager at US nuclear power plant says, “The reason I like JAWS 2.0 is that it has the capabilities that we haven’t been able to find anywhere else without hiring specialty vendors to do it for us.”

That capability to handle FOSAR in-house minimises critical down time. Over the decades, Sensor Networks, Inc. has developed retrieval toolkits that technicians can travel with or keep on site.

JAWS 2.0 users have fiberglass rods in varying lengths and diameters that can be used to push and pre-position the tool into place. Once the tool and camera are positioned correctly, users can rotate and position JAWS 2.0.

Visualising the entire process makes it easy to locate foreign materials and quickly remove them. It is also useful for other applications. One US nuclear plant uses it in the maintenance department, saying: “The ability to see what you’re going after is so critical. All too often, you’re going down into areas you physically cannot reach or access.

But this tool provides the ability to respond emergently in retrieval situations. Beyond that, we’ve also been able to use it for inspections because of the high-quality camera. It being waterproof adds to the capabilities and flexibility of the tool.”

The type of tool needed depends on many factors ranging from the material and size of the object to its distance. In some instances, a magnet might be the most effective option. In others, a noose or serrated jaws might be more appropriate. Not only does JAWS 2.0 offer interchangeable end-effectors, but it also has an integrated HD camera and a wired, battery-powered controller.

Author details: Bruce Pellegrino is Co-founder and VP marketing of Sensor Networks, Inc