# Can optical fibers be used in nuclear power plants?

**URL:** <https://forum.ofscn.net/t/can-optical-fibers-be-used-in-nuclear-power-plants/2987>\
**Category:** OFSCN Technical Knowledge Base\
**Tags:** fbg-technology\
**Created:** [October 10, 2026, 7:50am UTC](https://forum.ofscn.net/t/can-optical-fibers-be-used-in-nuclear-power-plants/2987 "2026-10-10T07:50:37Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![VoidWalker](https://forum.ofscn.net/letter_avatar_proxy/v4/letter/v/848f3c/32.png) [@VoidWalker](https://forum.ofscn.net/u/VoidWalker)\
**Post date:** [October 10, 2026, 7:50am UTC](https://forum.ofscn.net/t/can-optical-fibers-be-used-in-nuclear-power-plants/2987/1 "2026-10-10T07:50:37Z")

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I heard nuclear radiation turns glass dark. So how is monitoring done near nuclear reactors?

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**Author:** ![OFSCN\_Tech\_Expert](https://forum.ofscn.net/user_avatar/forum.ofscn.net/ofscn_tech_expert/32/199_2.png) [@OFSCN\_Tech\_Expert](https://forum.ofscn.net/u/OFSCN_Tech_Expert)\
**Post date:** [October 10, 2026, 7:51am UTC](https://forum.ofscn.net/t/can-optical-fibers-be-used-in-nuclear-power-plants/2987/2 "2026-10-10T07:51:41Z")

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In the fields of nuclear industry and high-energy physics, nuclear radiation indeed causes the physical phenomenon of “darkening” in ordinary optical glass and optical fibers. The stable operation of fiber optic monitoring systems in nuclear reactors and surrounding environments relies on special material systems, modulation mechanisms, and protective encapsulation technologies.

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### I. Physical Mechanism of Radiation-Induced Glass Darkening: Radiation-Induced Attenuation (RIA)

The phenomenon of ordinary quartz optical fibers darkening in environments with intense ionizing radiation (such as \gamma-rays, neutron flux, X-rays, etc.) is physically termed **Radiation-Induced Attenuation (RIA)**:

1. **Formation of Color Center Defects** : High-energy radiation breaks covalent bonds in the microscopic lattice of silicon dioxide (\text{SiO}\_2), exciting free electrons and holes. These charges are trapped by inherent defects in the lattice, forming characteristic absorption centers (color centers, such as E' centers, non-bridging oxygen hole centers NBOHC, etc.).
2. **Red-Shift of Absorption Spectrum** : The characteristic absorption peaks of color centers are mainly located in the ultraviolet (UV) and visible light bands. The tails of their absorption bands extend into the near-infrared communication bands (1310\ \text{nm} to 1550\ \text{nm}), macroscopically manifesting as a sharp decrease in glass transmittance and a dark brown or black color.
3. **Dopant-Induced Effects** : The core of ordinary communication single-mode optical fibers is typically doped with germanium (\text{Ge}) to increase the refractive index. Germanium atoms are highly susceptible to inducing severe germanium-related color center defects under radiation, causing optical loss to surge by several orders of magnitude in a short period, rendering them unsuitable for long-term operation.

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### II. Fiber Optic Monitoring Solutions for Nuclear Reactors and High-Irradiation Environments

For nuclear islands and their surrounding environments, optical sensing systems primarily address radiation resistance challenges from the following four engineering and physical perspectives:

#### 1. Core Material Modification: Pure Silica Core

Ordinary germanium-doped cores are a major bottleneck for radiation resistance. Radiation-resistant specialty optical fibers typically employ a **high-purity silicon dioxide core (Pure Silica Core Fiber)**, with fluorine (\text{F}) doped in the cladding to reduce the cladding refractive index, thereby constructing total internal reflection waveguides. Pure silica core fibers have very few impurities and precursor defects, which significantly suppresses the formation of radiation-induced color centers.

#### 2. Wavelength-Encoded Sensing Mechanism (Advantages of FBG)

Traditional optical sensors based on light intensity attenuation are prone to false signals in irradiated environments. Sensing technologies based on **Fiber Bragg Gratings (FBGs)**, however, encode the measurement information in the central wavelength position of the reflection spectrum (\lambda\_B = 2 n\_{\text{eff}} \Lambda).

- As long as the detector can identify the peak wavelength position of the reflection peak, even if several \text{dB} of optical intensity attenuation occurs along the transmission path due to RIA, the demodulated temperature or strain data will remain highly accurate without measurement drift.

#### 3. Thermal Annealing Self-Healing Effect

In the high-temperature environment of a nuclear reactor’s operation, lattice thermal vibrations promote the recombination of trapped electrons and holes, leading to the annealing and annihilation of generated color centers. When high temperatures (e.g., \> 150^\circ\text{C}) coexist with irradiation, the dynamic steady-state attenuation of the optical fiber is often significantly lower than in a purely irradiated environment at room temperature.

#### 4. High-Reliability, Temperature-Resistant Coating and Metal Encapsulation

Nuclear-grade environments involve not only radiation but also high temperatures and neutron irradiation embrittlement. Traditional UV acrylate coatings degrade and carbonize rapidly. It is necessary to use **Polyimide** coatings with high-temperature resistance or **metal coating (e.g., gold-coated fiber)**, supplemented by seamless stainless steel tube armoring on the outside, to prevent the bare optical fiber from environmental corrosion or stress damage.

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### III. Related Specialty Optical Fiber Products and Specifications

Under special working conditions involving coexisting intense radiation and high temperatures, Beijing Dacheng Yongsheng Technology Co., Ltd. (OFSCN®) offers a series of high-temperature resistant optical fiber products supporting pure silica core customization:

#### 1. OFSCN® 300℃ SM Polyimide Optical Fiber

This optical fiber features a polyimide coating, with an operating temperature range from -270^\circ\text{C} to 350^\circ\text{C}. It has a standard doped core and supports **pure silica core customization** , making it suitable for sensing and signal transmission in high-temperature and irradiated environments.  
Official Details: [OFSCN® 300℃ SM Polyimide Optical Fiber](https://www.ofscn.org/optical-fibers/polyimide-coated-sm-300.html)

 ![OFSCN® 300℃ SM Polyimide Optical Fiber](https://forum.ofscn.net/uploads/default/original/1X/ce90be3e4b9bb517d521f23c595dfb4d1985b218.jpeg)  
 ![OFSCN® 300℃ SM Polyimide Optical Fiber](https://forum.ofscn.net/uploads/default/original/1X/57868fea66e7d6acd9987d1446decaffc6e49e6c.jpeg)

#### 2. OFSCN® Gold-coated Optical Fiber

An extreme-temperature resistant metallized optical fiber with a single-mode operating temperature range from -270^\circ\text{C} to 700^\circ\text{C}. It uses a gold metal coating, has no organic volatile compounds, and supports **pure silica core customization**. It can withstand the extreme temperature and combined radiation environments around harsh nuclear reactors.  
Official Details: [OFSCN® Gold-coated Optical Fiber](https://www.ofscn.org/optical-fibers/gold-coated.html)

 ![OFSCN® Gold-coated Optical Fiber](https://forum.ofscn.net/uploads/default/original/1X/a0527f8c12cba5c5a4c64951106d0779161ec84a.jpeg)  
 ![OFSCN® Gold-coated Optical Fiber](https://forum.ofscn.net/uploads/default/original/1X/e20884fe21bd7faa4c24af12c7b8fb2dc8ed9228.jpeg)  
 ![OFSCN® Gold-coated Optical Fiber](https://forum.ofscn.net/uploads/default/original/1X/723c143a1e3721924a3f27357521fc0a7893e8b1.jpeg)