Apr 14, 2015

Level Solutions for Nuclear Power Plant Efficiency

As nuclear power plants continue to supply needed energy in many countries, ensuring power plant efficiency is crucial. Nuclear power plants must be able to handle the demands of energy consumption with minimum waste and maximum safety. Level instrumentation and pump protection can help maintain nuclear power plant efficiency during the storage, heating and cooling processes. In this blog post, the second of a two-part series on level solutions for the nuclear power industry, we will discuss level control applications for feedwater heaters and storage, diesel fuel storage tanks, lubrication oil storage, liquid waste storage, and cooling tower intake and basin levels. If you missed the first post, be sure to check it out, from April 7.

Feedwater Heaters and Storage
Application: Low and High Pressure Feedwater Heaters use extraction steam from the turbine to pre-heat feedwater destined for steam generation. The primary water sources for the heaters are the Condensers and Condensate Storage Tank. The Emergency Service Water System or the Ultimate Heat Sink (usually a river or lake) provides back-up feedwater to the SGs in the event of an interruption in the primary feedwater system.
feedwater tank

Challenges: Redundant control loops manage feedwater heater level to prevent liquid from rising into the extraction steam; keep tubes in the condensing zone immersed; keep the drain cooler flooded, and optimize heater performance. The primary and back-up feedwater sources are typically equipped with level switches for valve actuation and alarms.
Level Instrumentation:
-Series 3 Float-Actuated External Cage Level Switch or B40 Float-Actuated Level Switch for point level
-E3 Modulevel® Displacer Transmitter or Eclipse® Model 706 Radar Transmitter for continuous level
-Atlas™ or Aurora® Magnetic Level Indicators for visual indication

Diesel Fuel Storage Tanks
Application: Diesel-powered engine-generator sets provide emergency power to operate critical nuclear plant systems in the event of a loss of station service power. The main diesel fuel storage tank provides a fuel capacity for one to seven days of full-load generator operation. The main storage tank is connected to an indoor day tank holding less than 1,000 gallons.
Challenges: Main storage tanks typically require a fuel level indicator with a remote indication transmitter. Sensors actuating electrical pumps connected to the main tank continuously monitor day tank fuel level. Day tank high-level alarms can lock out supply pumps until a system reset. Low levels and critical low-levels actuate alarms and the system will display the low-level conditions.
diesel_storage_tanks

Level Instrumentation:
-Models A10 or B10 Displacer-Actuated Switches or Echotel® Model 961 Ultrasonic Switch for point level
-ECLIPSE Model 706 Guided Wave Radar, Pulsar® Model RX5 Radar Transmitter, or Jupiter® Magnetostrictive Level Transmitter for continuous level
-ATLAS or AURORA Magnetic Level Indicators for visual indication

Lubrication Oil Storage
Application: Nuclear plants operate many machines that require lubrication. Lubricants prevent damage caused by excessive friction and prolong equipment life. Oil is stored in stainless steel and carbon steel tanks. A generator gearbox lube oil system may have a reservoir with a capacity of 3,000 gallons and a turbine oil system may have a capacity of 150 gallons.
lubrication_oil_tanks

Challenges: Level monitoring of oil reservoirs will ensure the proper functioning of pumps, gearboxes, drives, compressors, materials handling equipment, generators and turbines. Temperature shifts in oil reservoirs affect media density that excludes some technologies, such as dP devices. Because ISO cleanliness levels increase oil change frequency, controls should be easy to remove.
Level Instrumentation: 
-ECHOTEL Model 961 Ultrasonic Switch or Tuffy® II Float- Actuated Switch for point level
-ECLIPSE Model 706 Guided Wave Radar or PULSAR Model RX5 Radar Transmitter for continuous level
-ATLAS or AURORA Magnetic Level Indicators for visual indication

Liquid Waste Storage
Application: Waste liquids from sumps, radioactive leakage collectors, the Reactor Cooling System (RCS), and allied systems are collected, stored and processed. Inactive wastes are discharged or reused; active wastes are collected for processing. Radioactive liquids can provide make-up to the RCS, the ECCS, and the spent fuel storage pool. 
Challenges: Waste liquids are collected and stored in large single- and double-walled tanks designed to suit radioactivity levels. Tanks are monitored for activity levels and their contents are processed, released or reused. Tank level instruments, frequently of redundant design, indicate inventory levels and protect against overfilling or underfilling that cavitates pumps. Prevention of tank overfilling.
liquid_waste_storage_tanks

Level Instrumentation:
-Models A10 or B10 Displacer-Actuated Switches for point level
-ATLAS or AURORA Magnetic Level Indicators for visual indication

Cooling Tower Intake and Basin Levels
Application: The hyperbolic cooling tower releasing clouds of water vapor is the iconic image of nuclear power. Warm water from the condenser is pumped to the natural draft cooling tower, distributed to remove waste heat to the ambient atmosphere through evaporation, and collected in a basin prior to being recycled back to the condenser.
cooling_tower_water_pumps

Challenges: The cooling tower’s intake structure, typically a vertical wet pit, requires level sensing and pump control. Water basin level controls maintain level through the addition of make-up water and are frequently configured with high and low level alarms.
Level Instrumentation:
-ECHOTEL Model 961 Ultrasonic Switch for point level
-ECLIPSE Model 706 Guided Wave Radar, or PULSAR Model RX5 Radar Transmitter or ECHOTEL Model 355 Non-Contact Ultrasonic Transmitter for continuous level
-Thermatel® Model TD1/TD2 Switch for flow and pump protection