Light Water Reactors

Light water reactors (LWRs) utilise enriched uranium fuel. In a pressurised water reactor (PWR), the water coolant is kept under high pressure to prevent boiling; it transfers heat to a secondary loop where steam is produced. In a boiling water reactor (BWR), the coolant is allowed to boil directly in the reactor core to produce steam. Both designs rely on large, robust containment structures and complex cooling systems. Supply chain considerations are well-established, albeit with limited suppliers, particularly for nuclear fuel (including enriched uranium, specialised steel pressure vessels, and steam turbines. Challenges include the high capital costs and the national nuclear infrastructure needed – for example the legal and regulatory framework, human resources, robust electrical grid capacity, linked to low demand for electricity – which can hinder accessibility for developing countries.

The nuclear safety risks associated with LWRs are related to direct exposure to radiation and contamination through the release of radioactive materials into the environment. This can be due to malfunctions or accidents, or the mismanagement of radioactive waste or spent fuel. Robust safety systems and regulations are essential to minimise these risks.

Stringent security measures are essential to ensure proper control and prevent, detect or respond to theft, sabotage, unauthorized access, illegal transfer or other malicious acts involving the nuclear fuel, other radioactive material or the nuclear facility itself.

The applicable IAEA safeguards agreement is implemented, involving, for example, inspections, nuclear material accounting, and containment and surveillance measures, to verify the peaceful use of nuclear materials.