Winfrith
Dorchester, Dorset
Reactor Data
Reactor Units
Every power reactor at this site as listed in the IAEA Power Reactor Information System (PRIS): reactor type and model, net electrical capacity, grid connection and commercial operation dates, and current status.
1 unit: 1 permanent shutdown.
| Unit | Type | Model | Net MWe | Construction | Grid | Commercial Op | Shutdown | Status |
|---|---|---|---|---|---|---|---|---|
| Winfrith Sghwr | SGHWR | SGHWR | 92 | 1963-05-01 | 1967-12-01 | 1968-01-01 | 1990-09-11 | Permanent Shutdown |
Capacity, milestones and suppliers
| Unit | Design MWe | Gross MWe | Thermal MWt | First Criticality | Reactor Supplier | Turbine Supplier | Notes |
|---|---|---|---|---|---|---|---|
| Winfrith Sghwr | 92 | 100 | 318 | 1967-09-01 | INTERNATIONAL COMBUSTION LTD. / FAIREY ENGINEERING LTD. | GENERAL ELECTRIC COMPANY (UK) |
Lifetime performance, through 2025
| Unit | Electricity Supplied | Load Factor | Energy Availability | Operating Factor |
|---|---|---|---|---|
| Winfrith Sghwr | 11.0 TWh | 60.6% | 61.4% | 60.8% |
Operator: UNITED KINGDOM ATOMIC ENERGY AUTHORITY
Owner: UNITED KINGDOM ATOMIC ENERGY AUTHORITY
Source: IAEA Power Reactor Information System (PRIS), as of 2026-10-19.
Research Reactors
Research and test reactors, critical assemblies and prototypes at this site, as listed in the IAEA Research Reactor Database: type, thermal power, first criticality, shutdown date, current status and what each is used for.
7 reactors: 6 decommissioned, 1 under decommissioning.
| Reactor | Type | Thermal Power | First Criticality | Shutdown | Status | Used For |
|---|---|---|---|---|---|---|
| ZENITH I | Graphite Co2 | 500 Wt | 1959-12-01 | Decommissioned | ||
| DIMPLE | Pool | 100 Wt | 1962-01-01 | 1995-06-01 | Decommissioned | |
| ZEBRA | Crit Fast | 1 kWt | 1962-12-01 | Decommissioned | ||
| HECTOR | Zero Power Htd | 100 Wt | 1963-03-01 | Decommissioned | ||
| Dragon | He Cooled | 20 MWt | 1964-01-01 | Under decommissioning | ||
| JUNO | Crit Assembly | 100 Wt | 1964-03-01 | Decommissioned | ||
| ZENITH II | Graphite | 1 kWt | 1972-03-01 | Decommissioned |
Source: IAEA Research Reactor Database (RRDB), as of 2026-10-13.
Fuel Cycle Facilities
Fuel cycle plants at this site, as listed in the IAEA Nuclear Fuel Cycle Facilities Database: what each plant does, its scale and design capacity, the years it operated, its current status and who operates it.
1 facility: 1 decommissioned.
| Facility | Type | Scale | Design Capacity | Operated | Status | Operator |
|---|---|---|---|---|---|---|
| NDA Fuel Manufacturing Facility (Winfrith) | MOX fuel fabrication (Mox Powder, Pellet, Pin, FA) | Pilot plant | 10 t HM/year | 1962–1992 | Decommissioned | Research Sites Restoration Ltd |
Source: IAEA Nuclear Fuel Cycle Facilities Database (NFCFDB), as of 2026-10-13.
Working Here
Per Diem Rates FY 2026
Per diem covers lodging and meals & incidental expenses (M&IE) for government and contractor travel near this facility. Rates are from the U.S. State Department foreign per diem tables for FY 2026.
$252
Lodging/Night
$108
M&IE/Day
$360
Total/Day
United Kingdom: rate for locations the State Department does not list separately
U.S. Department of State foreign per diem, for U.S. government and contractor travel.
Photos
Photos of this facility from the NukeWorker photo gallery. Click the header or any photo to browse the full album.
Facility Map
Interactive satellite map showing the facility's geographic location. Marker color indicates current status: green for online, red for offline, orange for reduced power. Click the header to open in Google Maps satellite view.
50.6815, -2.25641
Location & Contact
Physical address, phone number, and website for this facility. Use the directions link to get driving directions via Google Maps.
Plant Facts
About This Site
Written by NukeWorker from public records: facts that do not change. Operator, status and capacity come from the live data elsewhere on this page. Sources: Wikipedia: Winfrith Atomic Energy Establishment.
Winfrith is a nuclear research establishment in Dorset, England, on Winfrith Heath near Winfrith Newburgh, west of Wool. Construction of the site began in 1957, and it officially opened on 16 September 1960.
Read more
The ZENITH research reactor was operating by the end of 1959, followed by NESTOR in 1961, DIMPLE and ZEBRA in 1962, HECTOR in 1963, and JUNO and Dragon in 1964. Dragon was a 20 MW high-temperature gas-cooled reactor that ran until 1976. The Steam Generating Heavy Water Reactor, a power reactor, began operating in 1967 and was permanently shut down on 11 September 1990. In 1995, the eastern part of the site became the Winfrith Technology Centre.