Abstract
Fiber-optic sensors are gaining traction in the nuclear industry due to their high accuracy, compact
size, and ability to perform distributed measurements. To-date, most research has focused on the use
of fiber-optic sensors for monitoring and mapping of in-core temperatures. Radiation-induced attenuation is a
concern for any in-core application, but recent works have shown this to be manageable even at extremely
high dose (>1020 n/cm2
). Radiation-induced drift is arguably a more daunting challenge for in-core temperature
sensing. For advanced reactor applications, fiber-optic sensors could offer more value as a solution for structural
health monitoring if they can survive for extended durations at temperatures beyond the capabilities of
conventional technologies. These sensors could measure both static and dynamic (e.g., acoustic vibrations or
acoustic emissions)
strain, with the latter capable of filtering out low-frequency effects such as drift that occurs over longer
timescales. Utilizing fiber-optic sensors for structural health monitoring may not require exposure to in-core
radiation dose levels but instead presents a different set of challenges. Robustly attaching these sensors to various
reactor components such as pressure vessels, pumps, heat exchangers, and primary system piping is crucial.
The primary difficulty lies in managing the significant mismatch in thermal expansion between the fusedsilica optical fibers and metal components. This mismatch can induce substantial stress on the optical fiber
during operation, potentially leading to failure. Researchers are actively exploring a wide range of bonding
techniques
to address this issue. These techniques include adhesives, electroplating, welding, brazing, and advanced
manufacturing methods like additive manufacturing and electric-field assisted sintering.
Each method offers unique advantages and disadvantages regarding residual stress, maximum operating
temperature, and suitability for large-scale components. This paper summarizes ongoing research to identify and
optimize the most effective bonding techniques to ensure the long-term reliability and performance of fiber-optic
sensors in nuclear power plants.
size, and ability to perform distributed measurements. To-date, most research has focused on the use
of fiber-optic sensors for monitoring and mapping of in-core temperatures. Radiation-induced attenuation is a
concern for any in-core application, but recent works have shown this to be manageable even at extremely
high dose (>1020 n/cm2
). Radiation-induced drift is arguably a more daunting challenge for in-core temperature
sensing. For advanced reactor applications, fiber-optic sensors could offer more value as a solution for structural
health monitoring if they can survive for extended durations at temperatures beyond the capabilities of
conventional technologies. These sensors could measure both static and dynamic (e.g., acoustic vibrations or
acoustic emissions)
strain, with the latter capable of filtering out low-frequency effects such as drift that occurs over longer
timescales. Utilizing fiber-optic sensors for structural health monitoring may not require exposure to in-core
radiation dose levels but instead presents a different set of challenges. Robustly attaching these sensors to various
reactor components such as pressure vessels, pumps, heat exchangers, and primary system piping is crucial.
The primary difficulty lies in managing the significant mismatch in thermal expansion between the fusedsilica optical fibers and metal components. This mismatch can induce substantial stress on the optical fiber
during operation, potentially leading to failure. Researchers are actively exploring a wide range of bonding
techniques
to address this issue. These techniques include adhesives, electroplating, welding, brazing, and advanced
manufacturing methods like additive manufacturing and electric-field assisted sintering.
Each method offers unique advantages and disadvantages regarding residual stress, maximum operating
temperature, and suitability for large-scale components. This paper summarizes ongoing research to identify and
optimize the most effective bonding techniques to ensure the long-term reliability and performance of fiber-optic
sensors in nuclear power plants.
| Original language | American English |
|---|---|
| Title of host publication | Nuclear Plant Instrumentation and Control & Human-Machine Interface Technology (NPIC&HMIT 2025) |
| DOIs | |
| State | Published - Jun 15 2025 |