Sensor Technologies



Verify Containment Building Integrity:

The Challenge

The integrity of containment buildings used in nuclear reactors is critical to assure safe operation of the facility and to prevent contamination of the environment. Over time, these structures – which are usually fabricated from reinforced concrete – can degrade from exposure to the environment, inadequate design, or other factors. One way to insure integrity is to monitor the structure for the development of cracks, or any deformations that are beyond design limits. Accomplishing this monitoring is difficult due to the large size of these structures and the lack of accessibility to surfaces that could give indications of potential problems. Considerable improvements in the structural health database, reduced operational risk, and lower maintenance costs could be realized if a continuous monitoring system was employed.

Is there a sensor system that can monitor structural integrity in large concrete structures? Can problems such as concrete swelling or crack growth be tracked? Can the system be applied to existing structures? Can the sensors survive a wide range of environmental conditions? Is the system safe to use?

The Solution

FOX-TEK ’s FT fiber optic sensors and monitors are part of an engineered system with these capabilities. The sensors are light weight, flexible, are easily bonded to concrete, steel, polymers and composites, and are available with gage lengths up to 100 m. The sensors are passive, non-electrical devices and are immune to electromagnetic interference (EMI). For outdoor applications where lightning strikes pose a hazard, these sensors are an ideal choice. Although the sensors are quite rugged by themselves, additional protection from environmental is easily achieved with hermetic coatings.

FT sensors measure structural displacement and are readily compensated for thermal effects. When a concrete structure fractures, fiber optic sensors bonded circumferentially, detect a change in the thermo-mechanical strain response. When a structure swells due to corrosion of the steel reinforcement, the array of sensors identifies a change from the baseline response. Periodic site visits or continuous monitoring of the FT sensor strain signals are convenient ways to assess the structural health of the structure in comparison to the initial state.

Summary of Benefits

  • E arly detection of fracture growth or internal corrosion effects
  • Timely repairs to minimize further/structural damage
  Cost Savings
  • M aintenance/repair schedules based on actual integrity
  • Reduced risk of premature structural failure
  • Automated identification of problem areas
  • Reduction in unnecessary repairs
  • R educed risk of structural failure
  • Lower risk to maintenance personnel
  • Increased assurance of public safety
  • Lower probability of leaks and contamination