Technology

The SMR-300 stands at the forefront of modern energy innovation, embodying safety, security, and sustainability.

Holtec Britain’s SMR-300 will produce a steady source of low carbon electricity, safely bringing 300 MWe (net plant output) of green power to UK homes and businesses over the next 80 years.

The SMR-300 has been engineered using proven Pressurised Water Reactor (PWR) technology, using fuel similar to that already used at Sizewell B, and other new UK reactors under development including Hinkley Point C. 

We have drawn upon decades of proven PWR operating experience and Holtec’s manufacturing pedigree, as well as existing UK nuclear presence at Sizewell B. We have the ability to manufacture large reactor components in our own facilities which gives us quality control and value for money.

The result? A sustainable and reliable contribution to UK energy independence for generations to come.

Site Layout

The SMR-300 is a compact plant arrangement, with two 300 MWe reactors combined into a single power station. The design ensures that site boundaries such as the Exclusion Area Boundary (EAB), Low-Population Zone (LPZ), and Emergency Planning Zone (EPZ) can be as close to the site boundary as possible.

The site layout is designed to ensure that nuclear assets, including the reactor core, are protected and unauthorised access is prevented.

  1. CONTAINMENT ENCLOSURE STRUCTURE
  2. AIR COMPRESSION HOUSE
  3. REACTOR AUXILIARY BUILDIING
  4. COOLING TOWER FOR SERVICE WATER
  5. SERVICE WATER PUMP BUILDING
  6. SECURITY FACILITY
  7. ANNEX BUILDING
  8. WATER/WASTE WATER TREATMENT BUILDING
  9. RADIOACTIVE WASTE BUILDING
  10. INTERMEDIATE BUILDING
  11. DIESEL FUEL OIL STORAGE TANK
  12. PROTECTED AREA INTERIOR WAREHOUSE
  13. FUEL OIL PUMP SHELTER
  14. PORTABLE WATER STORAGE TANK
  15. DEMINERALIZED WATER STORAGE TANK
  16. WATER PUMP BUILDING
  17. DIESEL GENERATOR BUILDING
  18. AUXILIARY BOILER BUILDING
  19. SERVICE GAS SHELTER
  20. SECURITY FENCE
  21. CIRCULATING WATER PUMP HOUSE
  22. COOLING TOWER FOR CIRCULATING WATER
  23. MAIN STEP-UP TRANSFORMER
  24. STATION SERVICE TRANSFORMER
  25. UNIT AUXILIARY TRANSFORMER
  26. CONDENSATE STORAGE TANK
  27. TURBINE BUILDING
  28. UMAX INDEPENDENT SPENT FUEL STORAGE INSTALLATION
  29. ELECTRICAL BUILDING FOR NUCLEAR ISLAND

How does a Holtec SMR-300 work?

SMR-300 is a safe and secure two-loop Pressurised Water Reactor (PWR), that provides a steady source of clean energy from the fission heat from low-enriched uranium fuel.

Nuclear fission occurs when atoms are split apart, which releases energy and heats pressurised water which is carried through the coolant loops to the steam generator. Once inside the steam generator, the heat boils the water in a secondary loop, creating steam. This steam is then used to run the turbine, powering the generator.

The steam then enters the condenser, where it undergoes condensation and transforms back into water. This resulting water is then pumped out of the condenser and returns to the steam generator to be heated again.

The use of reactor coolant, or primary system booster pumps during normal operation is necessary to produce the 300MWe of power from each reactor for homes and industry. Importantly, the design employs gravity driven safety systems to ensure crucial safety functions for maintaining cooled and contained nuclear fuel are assured, noting those safety systems do not rely on pumps, external water, external power, or operator action. The plant design provides multiple and diverse pathways to reject heat from the core. The annular reservoir, a large body of water situated outside the primary containment, serves as an ultimate heat sink.

Spent fuel from the SMR-300 will be safely dry stored in our HI-STORM UMAX system, held in an underground vertical ventilated module. This proven system was designed by Holtec and is already in use at multiple reactor sites.

It has been licensed by the nuclear regulators in the United States for up to 100 years, with an expected long-term storage period possible of over 300 years, as supported by industry studies. A similar Holtec system has been licensed by the ONR in the UK for the safe storage of spent fuel for up to 100 years.

The materials and construction of the SMR-300 ensure a long service life by reducing life-limiting factors such as types of cracking and erosion. The plant is designed and engineered to reduce maintenance costs and provide ease of onsite inspections.