Monark
About
The Monark is a heavy water reactor with an electrical output of approximately 1,000 MWe. It belongs to the CANDU (Canada deuterium uranium) technology family and is intended for large-scale electricity generation using pressure-tube architecture with on-power refueling. The reactor is capable of cogeneration and can be used for district heating or desalination.
| Developer | AtkinsRéalis |
|---|---|
| Country of Origin | Canada |
| Size | Large |
| Type | Heavy Water Reactor |
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Analysis
2
Deployment Timescale
Score Justification
The Monark is in early regulatory engagement, with planning underway for vendor design review. The design draws directly on established heavy water reactor technology from the CANDU family of reactors with extensive operating precedent. Modularization is limited, and the reactor has many components that must undergo lengthy qualification processes and construction requirements. The supply chain reflects established capability for heavy water reactor components and fuel services.
By indicator
- 1/4 Regulatory Engagement
To what extent has the reactor developer engaged with a recognized nuclear regulatory authority in the licensing process? (30% of total score) - 4/6 Technology Precedent
Has the reactor design, or a sufficiently similar design, been certified anywhere in the world? (10% of total score) - 1/3 Modularity
What share of total reactor systems can be manufactured off-site in controlled factory environments rather than constructed on-site? (15% of total score) - 1/4 Specialization
To what extent do construction activities and components require lengthy qualification processes? (15% of total score) - 5/5 Supply Chain
How mature and available are suppliers for key reactor components and fuel services? (30% of total score)
1
Overnight Cost
Score Justification
The Monark has high overnight capital costs driven by large containment structures and items requiring long-lead qualification processes, such as the calandria vessel and tubes. It also has limited factory assembly.
By indicator
- 1/4 Component Cost
What is the expected cost of the reactor’s major components? (40% of total score) - 1/6 Construction Cost
To what extent does the design reduce construction cost and risk through modular fabrication and limited nuclear-grade specialization? (60% of total score)
2
Operational Cost
Score Justification
The Monark’s Operational Cost is driven by high maintenance, staffing, and decommissioning requirements typical of large heavy water reactors. Maintenance costs also include the expensive production and procurement of heavy water. Fuel costs are low because the reactor uses natural uranium.
By indicator
- 3/3 Fuel Cost
What is the estimated cost of nuclear fuel per unit of electricity generated, including enrichment, fabrication, and back-end costs? (15% of total score) - 1/4 Maintenance Cost
What is the expected annual maintenance cost for the reactor and balance of plant systems, including consumables? (25% of total score) - 1/5 Staffing Level
How many full-time personnel are required to safely operate and maintain the reactor unit? (40% of total score) - 3/5 Spent Fuel & Radioactive Waste Management Cost
What are the expected operational costs associated with managing spent fuel, including interim storage, transport, disposal, or recycling? (10% of total score) - 1/5 Decommissioning Cost
What are the total lifetime contributions required for decommissioning, regardless of funding mechanism? (10% of total score)
1
Cost Predictability
Score Justification
The Monark’s cost and schedule predictability are limited by the absence of a built prototype and the design’s limited modularity.
By indicator
- 0/5 Prototype
To what extent has the reactor design been built, demonstrated, or commercially deployed in practice? (75% of total score) - 1/3 Modularity
What share of total reactor systems can be manufactured off-site in controlled factory environments rather than constructed on-site? (25% of total score)
4
Security
Score Justification
The Monark uses natural uranium fuel, which eliminates the need for enrichment. However, the combination of natural uranium, efficient heavy water moderator, and low burnup rate of the Monark can produce weapons-usable plutonium, if irradiated on a very short time scale. The Monark incorporates security by design, including a hardened reactor building with controlled single-point access and the physical separation of vital systems to reduce vulnerability and enhance protection.
By indicator
- 3/3 Fuel
What is the enrichment level and composition of the reactor fuel? (40% of total score) - 3/4 Nuclear Material Production
What is the potential for the reactor to produce weapons-usable nuclear material? (40% of total score) - 1/1 Security by Design
Has the reactor developer built in security by design? (20% of total score)
3
Safety
Score Justification
While the Monark does not yet have an approved safety case from a national regulator, it builds on established CANDU heavy water reactor technology that has been licensed and deployed internationally. The Monark incorporates multiple passive shutdown systems, and its CANDU fuel has a lower heat density than most LWR fuels. It operates at high pressure, with redundant containment.
By indicator
- 0/2 Safety Case
How mature and publicly established is the reactor’s safety case with the regulator? (40% of total score) - 2/2 Shutdown Mechanism
How diverse, independent, and passive are the reactor’s shutdown systems? (20% of total score) - 0/1 Fuel With Safety Characteristics
Does the reactor use fuel with accident tolerance or inherent safety characteristics? (10% of total score) - 3/4 Pressure & Containment
How well does the reactor’s containment strategy protect from the release of radioactive material? (10% of total score) - 3/3 Passive Heat Removal
How long can the reactor remove core heat without operator intervention? (10% of total score) - 3/4 Coolant Reactivity
How chemically reactive is the reactor coolant? (10% of total score)
3
Spent Fuel & Radioactive Waste Management
Score Justification
The Monark uses natural-uranium CANDU fuel, a well-characterized waste form assessed as technically acceptable for Canada’s Adaptive Phased Management approach. Waste streams include spent fuel, activated structural materials, gaseous waste, heavy water, and light water. On-site storage requirements are substantial, reflecting established CANDU practice with large dry storage facilities. While spent fuel volume per unit of energy is high, the reactor’s low burnup results in comparatively low decay heat at long cooling times.
By indicator
- 1/1 Spent Fuel Licensing Precedent
Has the spent fuel form been previously licensed for disposal? (20% of total score) - 2/4 Waste Streams
How many distinct waste streams require separate conditioning or handling pathways? (20% of total score) - 1/3 On-Site Storage
How much on-site area is required for interim spent fuel storage? (10% of total score) - 1/3 Spent Fuel Volume
What volume of spent fuel is produced per unit of electricity generated? (15% of total score) - 2/2 Decay Heat
What is the decay heat output of spent fuel at the 50-year interim storage milestone? (20% of total score) - 2/2 Time to Interim Storage
What is the average time until spent fuel can be transferred to interim storage? (15% of total score)
5
Supply Chain
Score Justification
The Monark’s major components and fuel services are supported by an established commercial base, including pressure tube fabrication, heavy water systems, and natural uranium fuel production.
By indicator
- 2/2 Key Component Availability
To what extent are commercial or pilot-scale suppliers available for the reactor’s major components? (60% of total score) - 4/4 Fuel Availability
Are suppliers available for both fuel fabrication and enrichment required by the reactor design? (40% of total score)