Spherical Tokamak for Energy Production

Rating: Delivery Confidence Has remained Amber. This reflects sustained progress across design maturity, technology demonstration, commercial integration and site enablement, balanced against the inherent uncertainty and complexity of delivering a first‑of‑a‑kind fusion programme. While key technical risks remain these are well understood, actively managed, and supported by improving delivery capability, governance and industrial engagement.

Schedule: The project’s end‑date has remained unchanged. This reflects a deliberate decision to maintain the overall schedule while incorporating increased technical maturity achieved through successive design baselines, early Tranche 2a delivery, and strengthened delivery integration. Key enabling activities, including site acquisition progress, Construction Partner onboarding, and clearer understanding of critical technical risks, have improved schedule confidence without requiring changes to the headline end‑date. We expect to provide indicative ranges for the end date Q3 FY26/27.

Cost: The GMPP project is still at the planning stage (Pre-SOC or equivalent) and is not yet in a position to provide cost/schedule information

Source: NISTA Major Projects Annual Report 2025-26 (data)

Rating: Compared to financial year 23/24-Q4, the Infrastructure Project Authority's Delivery Confidence Assessment rating at 24/25-Q4 remained at AMBER. This is primarily due to the following factors‚ The intrinsic challenges of developing novel technologies and building a new industrial sector create delivery risks that could impact timelines, cost, and stakeholder confidence.

Schedule: Compared to financial year 23/24-Q4, the project's end-date at 24/25-Q4 remained at 01/04/2045. This is primarily due to the following factors‚ the intrinsic challenges of developing novel technologies and building a new industrial sector create delivery risks that could impact timelines.

Cost: The GMPP project is still at the planning stage (Pre-SOC or equivalent) and is not yet in a position to provide cost/schedule information

Source: NISTA Annual Report 2024-25 (data)

Rating: Compared to financial year 22/23-Q4, the Infrastructure Project Authority's Delivery Confidence Assessment rating at 23/24-Q4 remained at Amber. This is primarily due to the following factors. This reflects the intrinsically high ambition and accepted risk of STEP in driving a new strategic technology with potentially global benefits, balanced with good early progress but increasing delivery challenging over time. IPA gate 0/2 review completed 24/03. Delivery Confidence Assessment - Amber with 12 recommendations. Action plan put in place to support Outline Business Case with second IPA review was conducted in June ahead of Business case Review in July. The Delivery confidence Assessment was retained as Amber with 7 of the 12 recommendations from March closed and 5 acknowledged as 'In-Progress'. Outline Business Case was approved Aug 23 and Full Business Case will be submitted autumn 24. Key areas to address to support this level of ambition were identified by IPA as: -Increase fidelity of reporting to understand progress to plan and risk impacts (on track - new reporting in place through Programme Board). -Implementation of Review, Check, Assure to enable agile response to emerging information (on track) -Increase in capability commensurate with the increasing scale of the programme going into Tranche 2 (on track; new delivery body - UKIFS - planned to assume programme control from Nov 24) -Increased clarity on cross government sponsorship responsibilities (addressed via DESNZ sponsorship and new Fusion Strategy Delivery Board)

Schedule: Compared to financial year 22/23-Q4, the project's end-date at 23/24-Q4 increased from 2024-03-31 to 2045-04-01. This is primarily due to the following factors. This Project End date relates to the full programme rather than the current approved Phase. Year 2045, is an early estimate of the Spherical Tokamak plant's handover date to ongoing operations and will be revised as the programme plan is matured. The baseline date was erroneously referring to Tranche 1 completion of March 2024. Tranche 1 is now completed on time.

Cost: Compared to financial year 22/23-Q4, the project's departmental-agree Whole Life Cost at 23/24-Q4 increased from 218m. to 238m. This is primarily due to the following factors. The change in budgeted cost is due additional 20m funding approved in March 2023 for Tranche 1.

Source: IPA Annual Report 2023-24 (data)