29:
173:. This suffered from a number of problems due to corrosion and the customer soured on the design. Contracts for similar models in the US that were being signed were cancelled, and although Dragon suffered none of these issues, no orders were forthcoming in Europe either. By this time the market had largely standardized on the
250:
The TRISO design was never widely commercialized. The German designs suffered from a number of problems, and while Dragon operated successfully for many years, declining interest in alternative designs led to its closure without a larger commercial variant being built. As of 2019, these concepts have
363:
remain, and they are in the process of being decommissioned. During decommissioning, the reactor vessels will be placed in reactor safestores, other structures will be dismantled and stored, any remaining waste will be sent to allocated storage sites, and the soil will be removed as necessary to a
246:
By the mid-1960s the concerns about helium availability had largely faded, and in 1967 considered a non-issue. By this time the major concern was building a cooling system that was leak-proof enough to contain the gas while still being inexpensive enough to build. The UKAEA, in particular, had
196:
is encapsulated in a ceramic material that is capable of sustaining extremely high temperatures. This ensures the fuel remains encapsulated even if the reactor itself is compromised. This also allows the reactor to operate at higher temperatures, which results in higher efficiency.
234:
and meant the gas would not become highly radioactive over time. At the time, helium was available in the required quantities only from the USA, who classified it as a strategic material and carefully controlled its international sales. Risley
Nuclear Laboratories, developing the
243:(AGR), argued that the supply would be a serious issue, while CO2, in spite of any technical downsides, was trivially available. The OEEC team overseeing the project admitted that the helium issue "throw(s) doubt on the feasibility of employing it in an extensive power program."
348:), though later more lower enrichment (about 20%) fuel was used. The reactor resembled an enormous bottle, with the larger area at the bottom containing the active fuel within the reflector, and the smaller area on top holding additional fuel elements for reloading.
208:
to remove the heat and extract its energy. It is here that TRISO reactor designs may differ significantly. In the case of Dragon, the fuel was produced in small spherical pellets and then pressed into larger blocks containing the
339:
of the helium provided emergency cooling. The fuel used in the reactor was coated particles, consisting of micro-pellets of a fissile material (such as U235) surrounded by a ceramic outer layer. Initially most of the fuel was
225:
The choice of cooling gas for the design was highly controversial within the UK establishment. C.A. Rennie favoured the use of helium as it would reduce corrosion issues and had the added advantage of having a very low
213:
moderator formed into long hexagonal rods. The resulting blocks were then placed in fixed locations in the reactor. This is known as the "prismatic" design. While the Dragon reactor explored the prismatic design, the
162:
Originally conceived as a small research reactor, during the design phase it grew larger. The choice of helium coolant was made after a long debate within the UKAEA between proponents of helium and
653:
311:. Fuel was formed into tiny spherical pellets and then coated with ceramics. These were then mixed with the graphite and pressed together to form blocks of various shapes and sizes.
152:
327:, as well as its chemical inertness allowing it to operate at higher temperatures without fear of eroding the reactor materials. Higher temperatures also allow for more efficient
247:
already gone ahead with the AGR program and were noting the issues with corrosion due to the CO2, and raised concerns that helium might not be as inert as proponents suggested.
554:
368:. Finally, the site will be declassified as a nuclear licensed site, landscaped and returned to normal use. The contract for decommissioning the site has been awarded to
663:
579:
648:
356:
The
Winfrith site extended to 129.4 hectares (320 acres) of heathland in rural south Dorset, and nine different experimental reactors were located there.
678:
668:
260:
166:, with helium ultimately selected. Groundbreaking occurred in 1960. It operated from 1965 to 1976, and is generally considered extremely successful.
673:
252:
144:
42:
360:
170:
147:(UKAEA). Its purpose was to test fuel and materials for the European High Temperature Reactor programme, which was exploring the use of
658:
610:
643:
268:
504:
69:
284:
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104:
240:
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159:
international project. In total, 13 countries were involved in its design and operation during the project lifetime.
624:
177:(PWR) for the large buildout that occurred during the 1970s and 80s, and the decision was made to shut down Dragon.
365:
529:
389:
M S Barents (2000). "Decommissioning the
Winfrith technology centre – Environmental Restoration with a Purpose".
174:
510:. 18th International Conference on Structural Mechanics in Reactor Technology. SMiRT18-S05-2. Archived from
341:
319:, allowing additional fuel to be held in a ready area and loaded on-the-fly. Helium was used due to its low
151:
fuel and gas cooling for future high-efficiency reactor designs. The project was built and managed as an
320:
299:
was built for the construction and operation of experimental and research nuclear reactors. Dragon used
227:
156:
312:
169:
Dragon's construction was followed by similar work in the US, leading ultimately to the much larger
219:
132:
28:
316:
308:
201:
324:
231:
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is only possible when the blocks are placed together in certain configurations within a
618:. 18th International Conference on Structural Mechanics in Reactor Technology. Beijing.
236:
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511:
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205:
332:
215:
193:
438:"Demonstration HTR-PM connected to grid : New Nuclear - World Nuclear News"
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256:
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84:
71:
372:, and the final decommissioning phase has been deferred for twenty years.
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fuel concept became an area of significant interest. In this concept, the
304:
296:
272:
210:
136:
52:
530:
Operating experience with the DRAGON High
Temperature Reactor experiment
481:
505:"The Primary Circuit of the Dragon High Temperature Reactor Experiment"
200:
While the TRISO assembly provides the fuel, a reactor also requires a
626:
Europe's
Nuclear Power Experiment: History of the OECD Dragon Project
612:
The
Primary Circuit Of The Dragon High Temperature Reactor Experiment
300:
276:
264:
140:
56:
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189:
148:
555:"Dragon Fuel Waste in Magnox Encapsulation Plant at Sellafield"
416:
251:
been used in several further research reactors, including
391:
WM'00 Conference, February 27 – March 2, 2000, Tucson, AZ
432:
430:
222:, where the fuel elements are moved around the reactor.
359:
Of the nine reactors, only the Dragon
Reactor and the
331:
operation and make it more suitable for direct use as
153:
Organisation for
Economic Co-operation and Development
557:. Nuclear Decommissioning Authority. 25 October 2013
118:
110:
100:
63:
48:
38:
21:
459:
457:
654:Nuclear research institutes in the United Kingdom
267:as well as for small-scale commercial reactors,
16:UK experimental HTR, operated from 1965 to 1976
218:developed an alternative concept known as the
8:
180:As of 2023, Dragon is being decommissioned.
287:connected to the grid as of December 2021.
335:. In the case of a power failure, natural
664:Nuclear technology in the United Kingdom
476:
474:
472:
283:is under construction, with one unit at
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572:
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145:United Kingdom Atomic Energy Authority
43:United Kingdom Atomic Energy Authority
18:
131:was an experimental high temperature
7:
463:
403:
361:Steam Generating Heavy Water Reactor
171:Fort Saint Vrain Nuclear Power Plant
295:The Atomic Energy Establishment at
33:Cutaway model of the Dragon reactor
649:Former nuclear research institutes
580:"Winfrith's DRAGON loses its fire"
14:
679:1976 disestablishments in England
669:Science and technology in Dorset
528:Simon, R.A.; Capp, P.D. (2002).
27:
503:Simon, Rainer (7 August 2005).
190:tristructural-isotropic (TRISO)
149:tristructural-isotropic (TRISO)
674:1965 establishments in England
1:
609:Simon, Rainer (August 2005).
535:(Report). IAEA. INIS-XA--524
105:High-temperature gas reactor
241:Advanced Gas-cooled Reactor
143:, England, operated by the
695:
442:www.world-nuclear-news.org
366:Low Level Waste Repository
659:Nuclear research reactors
175:pressurized water reactor
26:
644:Defunct nuclear reactors
342:highly enriched uranium
303:gas as the coolant and
188:During the 1950s, the
417:"Triso Particle Fuel"
321:nuclear cross section
228:nuclear cross section
157:Nuclear Energy Agency
39:Operating Institution
623:Shaw, E. N. (1983).
323:which led to higher
230:which improved the
81: /
421:Ultra Safe Nuclear
220:pebble-bed reactor
133:gas-cooled reactor
85:50.6840°N 2.2694°W
317:neutron reflector
309:neutron moderator
202:neutron moderator
126:
125:
111:First Criticality
686:
630:
619:
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582:. Archived from
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517:on 26 July 2011.
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90:50.6840; -2.2694
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370:Costain Nuclear
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352:Decommissioning
325:neutron economy
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232:neutron economy
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89:
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586:on 4 June 2011
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269:Fort St. Vrain
237:carbon dioxide
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164:carbon dioxide
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65:
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50:
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24:
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22:Dragon reactor
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329:steam turbine
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239:(CO2) cooled
238:
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206:cooling fluid
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119:Shutdown date
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41:
37:
30:
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20:
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603:Bibliography
588:. Retrieved
584:the original
559:. Retrieved
549:
537:. Retrieved
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512:the original
498:
486:. Retrieved
445:. Retrieved
441:
420:
411:
406:, p. 2.
399:
390:
384:
358:
355:
333:process heat
294:
253:Peach Bottom
249:
245:
224:
216:West Germany
199:
194:nuclear fuel
187:
179:
168:
161:
128:
127:
629:. Pergamon.
346:uranium-235
344:(about 93%
313:Criticality
291:The reactor
88: /
64:Coordinates
638:Categories
482:"Winfrith"
447:2022-07-25
376:References
337:convection
285:Shidao Bay
73:50°41′02″N
590:24 August
488:24 August
464:Shaw 1983
404:Shaw 1983
364:suitable
76:2°16′10″W
59:, England
484:. Magnox
305:graphite
297:Winfrith
273:THTR-300
211:graphite
137:Winfrith
53:Winfrith
49:Location
307:as the
184:Concept
561:7 June
539:7 June
301:helium
277:HTR-PM
275:. The
265:HTR-10
263:, and
204:and a
141:Dorset
129:Dragon
57:Dorset
616:(PDF)
533:(PDF)
515:(PDF)
508:(PDF)
281:China
592:2016
563:2021
541:2021
490:2016
271:and
261:HTTR
122:1976
114:1965
101:Type
279:in
257:AVR
139:in
135:at
640::
571:^
471:^
456:^
440:.
429:^
419:.
259:,
255:,
55:,
594:.
565:.
543:.
492:.
466:.
450:.
423:.
393:.
155:/
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
