Spherical Tokamak For Energy Production

Infrastructure and Construction

Record date: 31 March 2026

Whole-life cost: Not disclosed
Published schedule: 16/07/2018 – 01/04/2045
NISTA delivery confidence: AMBER
Senior responsible owner: Paul Methven

What the project is for

The STEP (Spherical Tokamak for Energy Production) Programme is the UK Government’s flagship mission to design, demonstrate and de‑risk a prototype fusion power plant, while creating the industrial, commercial and regulatory foundations of a future UK fusion energy sector. STEP is therefore not just an infrastructure project. It is a national capability‑building programme, with delivery of a prototype plant at West Burton by the 2040s acting as the anchor for wider economic, technological and industrial outcomes.

Departmental delivery commentary

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

Benefits

Exempt under Section 22 - Information intended for future publication