LEAD COOLANT IN NUCLEAR POWER

Lead Coolant is a type of Liquid metal coolant which is used for meeting the requirements of natural safety and having sufficient margins for the development of large-scale nuclear power.

Properties of Lead Coolant, required in Nuclear Reactors

•   Ensure an intensive and stable heat exchange at as low power consumption rate for pumping as possible
•   Have a low chemical activity for reducing the danger during handling and improving the corrosion resistance of structural materials
•   Have a sufficient heat resistance
•   Be accessible and convenient during storage and transportation
•   Have a higher boiling temperature and a lower melting temperature (for liquid phase operation in a wide temperature and pressure range)
•   Have a small neutron capture and scattering cross sections (to ensure as low losses of neutrons during nuclear reactions as possible)
•   Be low activated during exposure to radiation (to reduce the activity of the plant's primary circuit).
•   Be stable during in pile radiation exposure

Usefulness of LEAD Properties in Nuclear Reactor

• High Density of Lead
  
  It provides for the possibility of circulating the coolant without increasing reactor dimensions. It excludes the fall of fuel assemblies to the core and damage during refueling.

• Low Moderation and Absorption of Neutrons
  
  It allows using wide lattices which results in
       •   Low power consumption for pumping and high level of natural circulation
       •   The possibility of using sheath less fuel assemblies and exclusion of their overheating during local flow blockage.

• Good Reflection Properties
  
  The substitution of the uranium reflector with a lead reflector has allowed reducing neutron leakage and improving neutron field equalization
  Possibility of regulating the reactor through lead substitution with gas.

• High Melting and Boiling Temperature
  
  The absence of high pressure in the lead circuit and a relatively high freezing temperature, Preclude accidents involving the loss of coolant and core cooling, melting of fuel elements, leakage of radioactive lead to the reactor rooms due to lead freezing and crack remedy.