Sizewell C cost overrun scrutiny: infrastructure and risk takeaways for engineers
Reviewed by Joe Ashwell
First reported on New Civil Engineer
30 Second Briefing
Sizewell C’s leadership and government officials faced the House of Commons Public Accounts Committee over cost overrun risks and transparency on the twin EPR nuclear plant planned to deliver 3.2GW on the Suffolk coast. MPs pressed for clarity on contingency budgeting, contract structures and the impact of inflation on major civils packages, including marine works and the main nuclear island. The session also covered enabling infrastructure such as site access roads, earthworks platforms and grid connection timelines, with concerns about schedule slippage and long-term value for money.
Technical Brief
- PAC scrutiny focused on how Sizewell C’s civils and marine packages are being let and priced.
- MPs pressed for detail on which works are already under contract versus still in competitive tender.
- Questions targeted how risk is shared between Sizewell C Ltd, main civils contractors and specialist marine suppliers.
- Committee members queried how contingency is allocated between enabling works, nuclear island and offshore structures.
- Evidence session examined how contract indexation is handling construction inflation across long-duration civils packages.
- Grid connection phasing and its dependency on completion of specific off-site civils corridors was probed.
- MPs sought clarity on interfaces between road access works, earthworks platforms and subsequent nuclear-island construction sequencing.
Our Take
Our database shows Sizewell C appearing repeatedly alongside Hinkley Point C and EDF in recent infrastructure pieces, signalling that UK nuclear new‑build is being treated as a linked programme where lessons on cost control and delivery from Hinkley will inevitably be scrutinised by the Public Accounts Committee.
AtkinsRéalis’ five‑year framework with EDF and Sizewell C, noted in a May article, suggests that design and assurance responsibilities are being consolidated with a small group of repeat contractors, which may help address PAC concerns on scope creep but also concentrates risk if early assumptions on programme cost prove optimistic.
Prepared by collating external sources, AI-assisted tools, and Geomechanics.io’s proprietary mining database, then reviewed for technical accuracy & edited by our geotechnical team.
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