HOW THEIR CONSTRUCTION IS EXPECTED TO CHANGE

Small modular nuclear reactors (SMRs) are – as their name implies – smaller, modular versions of commercial reactors. Many of these reactors address risks in new, innovative, and safer ways and use novel materials, engineering, and construction in the process. Though the construction of an SMR will not begin in Saskatchewan until 2029 (at the earliest), planning in advance will be key to deploying them in a timely manner.1 SaskPower has chosen the GE-Hitachi BWRX-300 small modular reactor for deployment in Saskatchewan (the "BWRX300"). The BWRX-300 is a water-cooled reactor using natural circulation and implements novel passive safety systems.2 Notably, the BWRX-300 is touted to have substantially lower construction costs than traditional nuclear power plants and is expected to use "advanced concrete solutions and innovative techniques that have been proven in the oil and gas, tunneling, and power industries."3

A significant change imposed by the BWRX-300, as compared to traditional reactors arises out of its modularity. Modularity allows for the mass production of components that can be installed and constructed on site. This approach reduces construction time but involves novel materials4 and approaches to construction. The BWRX-300 is planned to incorporate the "Open Top Method" for its construction.5

The Open Top Method is an approach where equipment is installed into the nuclear containment site from the top down. Traditional nuclear reactors have a containment building wrapped around an auxiliary building, which houses the reactors' largest components. Installing these large components often results in delays and other challenges during installation because of their size and complexities.6.

In the past, these components have been installed using the "Side Method," where temporary openings in the containment walls are left to allow entry of the equipment.7 However, because of advancements in crane technology and the reduced size of these reactors, the BWRX-300 will be constructed using the Open Top Method. In this method, equipment will come through a vertical opening at the top of the building via "very heavy lift" cranes.8

The Canadian Nuclear Safety Commission (CNSC) has begun revising its regulations to provide flexibility for the construction of nuclear reactors to account for these approaches to construction and modularity. However, there will likely be some inevitable precautions that will remain, including those concerning the regulatory approach of "defence-in-depth."

Nuclear regulations aim to "control, cool, and contain" nuclear reactors in the event of a nuclear accident. The historic approach to achieve this principle is through "defence-in-depth," which uses redundancy to ensure safety. For example, nuclear regulations promote the use of various levels of containment and barriers to ensure that nuclear accidents are contained.

The passive safety systems employed by the BWRX-300 are innovative and likely reduce the need for physical containment to achieve "defence-in-depth" as compared to traditional reactors.9 While it is not yet clear how Canadian regulations will address this, any variation to traditional approaches will be assessed on a case-by-case basis, as per the CNSC's recent update to its regulations.10

It will be exciting to see how the BWRX-300 is deployed in Saskatchewan and what innovation it will bring to the construction industry. Other jurisdictions, such as Ontario Power Generation,11 have also made the BWRX-300 their reactor of choice and so the experienced gained by Saskatchewan will be applicable elsewhere. Though there are many years before SMRs will be constructed in Saskatchewan, early planning will be key to their quick deployment.

Footnotes

1. Saskatchewan Power Corporation, "Planning for Nuclear Power" (12 Jun 2023) Planning for Nuclear Power (Blog), online: ( https://engage.saskpower.com/hub-page/planningfor-nuclear-power-2 ).

2. General Electric Hitachi, "BWRX-300" Nuclear Power Plants (Blog) online: ( https://nuclear.gepower.com/build-a-plant/products/nuclear-power-plants-overview/bwrx-300 ).

3. Ibid.

4. Kevin Lee, "The Canadian Nuclear Safety Commission: Readiness Activities to regulate Small Modular Reactors" (Paper delivered at the 26th International Conference on Nuclear Engineering, 22–26 July 2018) [unpublished] at 2.

5. General Electric Hitachi, supra note 2.

6. Mark Gino Aliperio, "Open Top Method: Advanced Construction Technology for Nuclear Power Plants" (26 August 2021) Pulse (Blog) online: ( https://www.linkedin.com/pulse/open-top-method-advanced-constructiontechnology-nuclear-aliperio ).

7. Ibid.

8. Ibid.

9. E S Lyman, "The Pebble-Bed Modular Reactor (PBMR): Safety Issues" 30:4 Physics and Society 16 ("PBMR promoters claim that a robust containment is unnecessary . . . [and] [t]hey argue further that such a containment would actually be detrimental to safety because it would inhibit heat transfer" at 17).

10. Andrew Dusvic, "The CNSC Takes Further Steps to Regulate SMRS in its Update to REGDOC-3.5.3, Regulatory Fundamentals" (6 April 2023) McKercher Blog (Blog) online: (https://www.mckercher.ca/resources/the-cnsc-takesfurther-steps-to-regulate-smrs-in-its-update-to-regdoc-3-5-3- regulatory-fundamentals).

11. World Nuclear News, "OPG chooses BWRX-300 SMR for Darlington new build" (2 December 2021) World Nuclear News (Blog) online: ( https://www.world-nuclear-news.org/Articles/OPG-chooses-BWRX-300-SMR-for-Darlington-newbuild ).

Originally Published by We Build – Saskatchewan's Construction Magazine.

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