Nuclear Power Plant Safety Systems

/ Planning and Prevention is key /

When thinking of nuclear power most people associate the accidents at Three Mile Island (USA 1979), Chernobyl (Ukraine 1986) and Fukushima (Japan 2001) with what could happen. While these events are tragic, they are rare and nuclear power still remains to be one of the safest means of power generation. The industry has been extremely successful with over 17,000 cumulative reactor years of commercial operation. This proves a devotion to quality, safety and innovation by everyone involved in the planning and design of a nuclear power plant and its safety systems.

Today there are approximately 450 nuclear power plants worldwide operating in 30 countries with about 50 power reactors currently being constructed. This equates to a massive amount of instrumentation, power and control cables, pressure transmitters, and sensors. Planning and preventive maintenance is necessary to avoid an accident.

With nuclear power plants having a design life of 40-60 years it is necessary to properly plan to avoid Design Basis Events. Cables connected to safety systems must without fail withstand the extreme environments of a Loss of Coolant Accident, High-Energy Line Break, or Main Steam Line Break. Cables are tested with accelerated thermal aging tests and are estimated to last the life of the plant. These challenges include stressors caused by temperature, radiation, vibration, and electricity. Testing can only go so far; real-world applications and conditions are impossible to predict and inevitably, costly shut downs do happen.

Replacing failed cables and conductors is an extremely difficult task in nuclear power plants due to several variables. Areas in the reactor containment building contain high radiation fields and are not easily accessible. Cable trays can contain a large number of cable runs with lengths of up to 1000ft. These are densely packed and generally require the failed cable to be completely removed in order to make room for the new cable. Traditional aging management methods, such as equipment replacement, require a process to be shut down.

However recent technologies commonly known as online monitoring allow plants to monitor the condition of their installed key instrument and control components while the plant is operating. Conduit tested to IEEE standards 383 and 323 can give an added protection to critical emergency core cooling systems, lowering the frequency of cable replacement. Where flexibility and liquid-tight are a necessity, Anamet Electrical’s Nuclear Wiring Conduit (NWC) is the design of choice.

In this age of automation, it is critical that all instrumentation and cabling is rigorously tested and overprotected against radiation, vibration, and abrasions. More and more nuclear power plants are being built and maintained. It is essential the safety of workers and citizens remains the number one priority in the design and planning of safety systems.