Forum : Déclassement

Un grand nombre de réacteurs nucléaires mis en service avant les années 1980 partout au monde atteindront la fin de leur durée de vie utile dans les prochaines décennies.

Le déclassement nucléaire désigne les mesures prises pour mettre hors service définitivement une installation ou un site nucléaire de manière à assurer la santé et la sécurité des personnes et à protéger l’environnement. Les activités de déclassement doivent satisfaire aux exigences des politiques nationales et du cadre réglementaire de la sûreté.

Les politiques nationales sur la gestion des déchets et le déclassement prévoient souvent des éléments qui peuvent influencer le choix de la stratégie de déclassement (déclassement immédiat, déclassement différé et déclassement in situ) et avoir une incidence sur le calendrier, l’infrastructure et l’environnement et avoir des répercussions socio-économiques. 

Au Canada, les propriétaires de déchets doivent financer et gérer le déclassement de leurs installations et prendre toutes les mesures de gestion des déchets applicables.

Avant de participer à la discussion, veuillez lire les lignes directrices sur la modération du site Web de mobilisation en matière de gestion des déchets radioactifs et sur la publication de commentaires.

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1. Selon vous, quelles sont les considérations générales qui devraient influencer le choix de la stratégie de déclassement par les exploitants nucléaires et qui devraient être un élément de la politique en matière de déchets radioactifs du Canada?

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2. De quelle façon la politique du Canada devrait-elle viser l’établissement d’objectifs finaux pour le déclassement?

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Portrait de Ole Hendrickson
Ole Hendrickson
jan 29, 2021 - 16:06

The discussion paper states:

"In-situ decommissioning cannot be considered a reasonable decommissioning option for planned decommissioning of... future nuclear facilities... where removal is possible and practicable.”

This raises questions: "Is removal of proposed small modular reactor (SMR) designs – such as the MMR proposal at Chalk River or the ARC-100 and Moltex proposals in New Brunswick "possible and practicable" after shut-down? Does Canada’s nuclear regulator intend to include removal costs in the “financial guarantee” for decommissioning? Or is the plan to dispose of them “in-situ” (on-site) - rather than at an NWMO repository)?

The paper goes on to state:

“In-situ decommissioning may be considered a solution… for legacy sites."

The IAEA’s General Safety Requirements document, Decommissioning of Facilities, says that in-situ decommissioning (also known as entombment) “is not considered a decommissioning strategy and is not an option in the case of planned permanent shutdown. It may be considered a solution only under exceptional circumstances (e.g. following a severe accident).” The 2019 IAEA review of Canada’s nuclear safety framework calls for “revising… current and planned requirements in the area of decommissioning to align with the IAEA guidance that entombment is not considered an acceptable strategy for planned decommissioning of existing NPPs and future nuclear facilities.”

As in-situ decommissioning is not an option according to the IAEA’s safety requirements, it should be removed from the list of options in the discussion paper. The discussion paper should state that in-situ decommissioning is not an option for “legacy sites” or “future nuclear facilities.”

"Prompt” and “deferred” decommissioning - dismantling and removal of nuclear facilities- are the only options deemed acceptable by the IAEA. These are the only options that should be included in Canadian policy. Nuclear reactors are water-cooled and built near major water bodies. Their wastes must be isolated and contained in a facility located AWAY from major water bodies.

Policy should identify “prompt” decommissioning as the preferred option, and should discuss why prompt decommissioning is preferred, and under what circumstances decommissioning might need to be deferred. It should note that one such circumstance is that a suitable waste management facility is lacking. Canadian decommissioning policy should include development of a long-term decommissioning waste management facility so that decommissioning can be carried out promptly and is not deferred indefinitely.

Canada's decommissioning policy should require accurate estimates of funding required for decommissioning of nuclear facilities and for long-term management of decommissioning wastes. It should address financial guarantees and acknowledge the need to ensure that adequate funding is available so the burden does not fall upon future generations of taxpayers.

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Portrait de D. Bilinsky

IAEA General Safety Requirements (GSR), Specific Safety Requirements (SSR) and Safety Guides (SSG) reflect international consensus of established requirements and recommendations take precedence over supporting informational series publications such as the IAEA Safety Report referenced within NRCan's Decommissioning Discussion Paper. Contrary to NRCan’s presumption, the only special circumstance acceptable to the IAEA where in situ confinement for reactors may be considered is for nuclear facilities that have been damaged in a severe accident. The 2019 IAEA Integrated Regulatory Review of Canada’s nuclear regulatory framework previously stated the strategy of in situ confinement (disposal) for reactors is not in full compliance with IAEA safety standards GSR Part 6 and SSG-47. Nevertheless, NRCan advocates in situ decommissioning and Section 5.1 of CNSC regulatory document REGDOC-2.11.2 may consider in situ decommissioning for legacy sites, even in situations where removal is possible and practicable.

Canadian Nuclear Laboratories (CNL) has proposed in situ decommissioning of the Whiteshell WR-1 reactor in Pinawa, Manitoba via creation of an Intermediate Level Waste (ILW) disposal site. The removal of the WR-1 reactor followed by ILW consolidation at a larger ILW site is preferable to creating another long-term legacy liability ILW disposal site. Consolidation of smaller nuclear waste inventory sites reduces the burdens on future generations of securely maintaining and monitoring multiple long-term legacy sites while still providing protection of people, the environment and national security. Consolidation of nuclear waste sites also has the benefit of increasing the number of locations released for reuse by future generations.

Canada should improve alignment of nuclear policies and regulations to internationally agreed standards, specifically key fundamental recommendations found in IAEA GSR 6 and SSR 5 by; dismantling and removing nuclear facilities where possible and practicable, and due to the presence of long-lived radionuclides, ILW requires a greater degree of containment and isolation than that provided by near-surface disposal. ILW disposal at significant depth provides greater protection against the migration of long-lived radionuclides and a potential future glacial degradation event.

Verifiable policy and regulatory alignment with IAEA safety standards will build trust with Canadians and provide assurance that the Government of Canada is serious about its commitment to meet international standards and best practices in achieving its top priority of protecting the health and safety of Canadians and the environment, now and in the future.

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Portrait de Peter Baumgartner
Peter Baumgartner
mar 16, 2021 - 13:29

Radioactive Waste Management Policy has only three categories:
- Waste Production
- Waste Storage
- Waste Disposal

Waste Production is the generation and collection of waste products from the mining, processing, fabricating, handling, decommissioning and contaminating of the derivative desired infrastructures and products. Note that decommissioning is a Waste Production activity and not a stand-alone waste production process. Waste minimization is an over-riding consideration in the Radioactive Waste Management Policy, particularly under the Waste Production category where the vast balk of the waste is produced.

Waste Storage is the temporary and safe containment of the waste products until appropriate waste disposal facilities are built and enter operation.

Waste Disposal is the active construction, operation and ultimate closure of approved facilities to permanently and safely contain and isolate the radioactive waste for the long-term protection of the people and environment.

As mentioned previously, decommissioning is a Waste Production process. It is not, and should not be, a Waste Disposal process and should not be confused as such by poor language. Great pains are made to define the term “In-situ Decommissioning” in which “… some or all of the radioactive contaminants are disposed of in place, which may result in the creation of a waste disposal site.” If it is disposed in place, then it “is” a disposal site, not “may create a disposal site.” The discussion of “In-situ Decommissioning” should be retitled as “In-situ Disposal” and should be solely discussed under the Waste Disposal process.
The discussion of decommissioning research and development (R&D) legacy sites uses the weak argument that their initial design and construction did not consider decommissioning as part of the design process. This does not prevent the taking of proper action to remediate this historical omission. Proper engineering plans and designs for remediation options should be undertaken and be impartially reviewed and evaluated before any decision for In-Situ Disposal is ruled upon to eliminate bias. The current unavailability of an operating disposal facility should not be a consideration as this does not pertain to other non-R&D legacy facilities.

Waste minimization is briefly discussed since decommissioning will, not may, produce radioactive and other hazardous wastes which must also be disposed, not hidden under the guise of the weaker term, managed.

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Portrait de D. Bilinsky
mar 17, 2021 - 11:27

The removal and replacement of legacy site research reactor vessels has been conducted by AECL three times, once following a severe reactor accident. CNSC REGDOC-2.11.2 Section 5.1 may consider in situ decommissioning for legacy nuclear sites where decommissioning was not planned as part of the design. Although decommissioning of AECL's WR-1 reactor at Pinawa Manitoba may not have been planned as part of design, it was likely a design consideration as reversal of installation is evident as a possible and practicable reactor vessel removal method.

WR-1 was designed with facilities and equipment to replace fuel channel pressure tubes; a standard operating procedure safely conducted on numerous occasions. Fuel channel replacement, including fuel handling, required about 12 hours per channel [1]. Extending removal of currently defueled pressure tubes to include volume reduction is practicable. A Bruce Power video [2] demonstrates volume reduction for CANDU pressure tubes. WR-1 fuel channel volume reduction is straightforward due to existing handling equipment and the vertical orientation of the fuel channels. Following removal of a fuel channel, the fuel channel transfer flask could be positioned over a repurposed room under the main floor of the reactor building where the fuel channel is lowered for volume reduction. The compacted volume of all WR-1 fuel channels is ~ 1 cubic meter and fuel channel removal provides ~ 47% reduction [3] in overall reactor core activation radionuclide activity. Removal of the reactor main floor rotating deck plates provides additional direct access to the top of the reactor for use of advanced technologies to dismantle and remove the remaining 53% of core activation radionuclide activity found largely in the reactor vessel.

During the history of WR‐1 operations there were about 150 documented nuclear fuel failures, each contributing a small portion to the 1 kg upper bound estimate [3] of high-level radioactive particles deposited in reactor systems. Manitoba’s High-Level Radioactive Waste Act does not permit disposal of high-level waste in Manitoba, making removal of the irradiated fuel deposits in WR-1 systems necessary, also required by Section 8.10 of IAEA General Safety Requirement Part 6. WR-1 removal followed by waste consolidation at a larger disposal site eliminates creating another legacy liability in the form of a near-surface intermediate-level waste disposal site.

The Government of Canada should reduce the number of long-term legacy liability sites by dismantling and removing nuclear facilities where possible and practicable, regardless of whether decommissioning was planned as part of design.

1) IAEA-SM-99/33 (1967), Current Status of Canadian Organic Cooled Reactor Technology; https://www.osti.gov/biblio/4557804
2) Bruce Power (2009), YouTube Video; https://www.youtube.com/watch?v=L-HgGjzswAk
3) CNL (2016), WR-1 Reactor Radiological Characterization Summary, WLDP-26100-041-000-001

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