Trawsfynydd Nuclear Power Station Survey Of Major Industrial Sites

Yr adeilad modern a godwyd i Storio Gwastraff Lefel Ganolig ynddo fel rhan o’r broses ddatgomisiynu.
The modern Medium Level Waste Storage Building constructed as part of the decommissioning process.
(Image/Llun: DS2010_540_033 / NPRN: 30192)

Atomfa Trawsfynydd
Un o rolau’r Comisiwn Brenhinol yw arolygu safleoedd diwydiannol mawr sydd wrthi’n cael eu cau a sicrhau bod gennym gofnod o ffyrdd o fyw sy’n newid am byth.

Dechreuwyd codi’r atomfa ym 1959 a chychwynnwyd cynhyrchu trydan yno ym 1965 o dan y Bwrdd Canolog Cynhyrchu Trydan. Bu atomfa Trawsfynydd ar waith am chwe blynedd ar hugain a chynlluniwyd iddi gynhyrchu 500MW, digon i ddarparu trydan i ddinas o faint Manceinion. Fe’i caewyd er mwyn ei hatgyweirio ym 1991 a dechreuodd Magnox North wneud y gwaith datgomisiynu ym 1995 o dan yr Awdurdod Datgomisiynu Niwclear.

Erbyn hyn, mae rhyw 600 o bobl yn gweithio ar y safle ond mae 99.99 y cant o’r defnydd ymbelydrol wedi’i symud oddi yno. Y bwriad yw gostwng uchder adeiladau’r adweithydd a chlirio’r adeiladweithiau’n barod iddynt gael gofal a gwneud gwaith cynnal-a-chadw arnynt dros y naw deg blynedd nesaf. Yna, caiff y gwaith o glirio’r safle ei gwblhau ar ddiwedd y ganrif.

Syr Basil Spence, cynllunydd Eglwys Gadeiriol Coventry a Llysgenhadaeth Prydain yn Rhufain, wnaeth greu’r cysyniad pensaernïol. Cynlluniwyd y gwaith tirweddu cysylltiedig gan y Fonesig Sylvia Crowe i gyd-fynd â’r lleoliad hynod sensitif hwn. Buont yn gweithio gyda’i gilydd i arddangos yr adeiladau yn y dirwedd. Eu bwriad oedd i’r adeiladau efelychu maint castell canoloesol a godai’n ddramatig o’r llawr heb fod unrhyw adeiladwaith o’i gwmpas i darfu arno. Cynlluniwyd i’r gwaith ar y dirwedd guddio’r adeiladau ychwanegol a’r is-orsaf drydan enfawr. Ar bob ochr fe blannwyd coed gan ddefnyddio rhywogaethau brodorol i droi’r dirwedd yn rhan o’r amgylchedd lleol.

Y nodweddion amlycaf, sy’n sefyll yn noeth yng nghanol y mynyddoedd, yw dau adeilad yr adweithydd Magnox, dau sy’n 180 troedfedd o uchder. Mae eu paneli concrid yn cynnwys agregau lleol, ac ar eu harwynebau mae patrymau asennog sy’n lleddfu gwynder digyfaddawd y concrid safonol er mwyn iddynt allu plethu’n well i’r dirwedd. Yn 2003 fe chwalwyd neuadd enfawr y tyrbinau lle’r arferai’r adweithyddion greu ynni o’r ager dan wasgedd uchel , ac yn 2005 fe chwalwyd y tŷ ar lan y llyn a fyddai’n pwmpio dŵr allan i’w oeri yn yr awyr agored.

Trawsfynydd oedd yr unig atomfa yn y DU na chodwyd mohoni ar hyd yr arfordir - codwyd pob un o’r lleill ar y glannau iddynt gael digon o ddŵr i oeri’r adweithyddion. Dewiswyd safle Trawsfynydd am fod llyn wedi’i adeiladu yno ym 1920 ar gyfer cynllun pŵer trydan-dŵr ym Maentwrog. Ehangwyd y llyn i ddarparu 35 o filiynau o alwyni o ddŵr yr awr i oeri’r adweithyddion a chrëwyd cyfres o rwystrau i sicrhau bod y dŵr yn teithio holl hyd y llyn i oeri cyn iddo ddychwelyd i’r atomfa.

Mae’r Comisiwn Brenhinol wrthi’n gweithio i gofnodi’r safle ac i sicrhau bod y deunydd wedi’i archifo’n gywir. Mae’n cydweithio mewn tîm gyda Magnox North, Archifdy Meirionnydd, Amgueddfa Cymru, Trawsnewid, aelodau o’r gymuned leol a sefydliadau eraill, gyda chymorth Cadw a CyMAL. Prif rôl y Comisiwn yw tynnu ffotograffau o’r adeiladau a’r offer sydd yno ar hyn o bryd a darlunio i’r oesoedd a ddêl y broses ddatgomisiynu, proses sydd ynddi’i hun yn rhan fawr o hanes y safle. Mae ef hefyd wrthi’n cofnodi’r safle yn ei dirwedd ac yn gwneud cofnod ffotograffig o’r nodweddion cysylltiedig, fel y tai a godwyd ar gyfer staff yr atomfa.

Cysylltau:

• Cofnod Atomfa Trawsfynydd yn Coflein.
• Cofnod Tiroedd a Gerddi Atomfa Trawsfynydd yn Coflein.
• Ar wefan Magnox North cewch wybodaeth am eu gorsafoedd, fideos o amrywiol gamau chwalu’r atomfa, ac animeiddiad 3-D sy’n dangos yr hyn y mae’r datgomisiynu’n ei gynnwys.
• Cewch fywgraffiad o’r Fonesig Sylvia Crowe ar wefan y Landscape Institute.
• Cedwir archif y pensaer, Syr Basil Spence, yn swyddfeydd Comisiwn Brenhinol Henebion yr Alban. Mae’r archif yn cynnwys brasluniau o gysyniad Spence ar gyfer Trawsfynydd.

 

Gweithiwr wrthi’n rheoli robot y peiriant chwalu.
Operative controlling the robot demolition machine.
(Image/Llun: DS2010_540_030 / NPRN: 30192)

Trawsfynydd Nuclear Power Station
One of the roles of the Royal Commission is to survey major industrial sites that are closing down, making sure we have permanent records of ways of life that are changing forever.

Work on the power station began in 1959 with electricity production commencing in 1965 under the Central Electricity Generating Board. Trawsfynydd worked for 26 years, and was designed to produce 500MW, enough to power a city the size of Manchester. It was shut down for repair in 1991 and decommissioning started in 1995, carried out by Magnox North under the Nuclear Decommissioning Authority.

Some 600 people now work on the site but 99.99 per cent of the radioactive material has now been removed. The plan is to reduce the reactor buildings in height and clear structures ready for care and maintenance over the next ninety years, and then complete the site clearance at the end of the century.

The architectural concept was by Sir Basil Spence, designer of Coventry Cathedral and the British Embassy in Rome. The associated landscaping was designed by Dame Sylvia Crowe to fit the highly sensitive location. They worked together to display the buildings in the landscape, replicating the mass of a medieval castle, rising dramatically, uncluttered by surrounding structures. The contouring of the landscape was designed to hide ancillary buildings and the massive electrical substation. Planting of trees extended all around, using native species that would make the landscape part of the local environment.

The twin Magnox reactor buildings, each 180 feet high, are the dominant features, standing starkly in the mountain setting. Their concrete panels contain local aggregates, and have surfaces broken up by patterns of ribs to avoid the stark whiteness of standard concrete, allowing them to better blend into the landscape. The huge turbine hall where energy was created from the high-pressure steam produced by the reactors was demolished in 2003, and the lakeside pumphouse for cooling water was demolished in 2005.

Trawsfynydd was the only inland nuclear power station built in the UK – all the others were constructed on the coast to give them plentiful water for cooling. The site was chosen because of its lake, built in 1920 for a hydro-electric power scheme in Maentwrog. This was enlarged to provide 35 million gallons of water an hour for cooling and a series of barriers was created to ensure that water travelled to the whole length of the lake to cool before returning to the power station inlet.

The Royal Commission is working to record the site and ensure that material is properly archived, collaborating in a team with Magnox North, Merioneth Archives, the National Museum of Wales, Trawsnewid, members of the local community, and other organisations, with the support of Cadw and CyMAL. The Commission’s main role is to photograph the existing buildings and equipment and to capture for posterity the decommissioning process, which is itself a major part of the history of the site. It is also recording the site in its landscape setting and making a photographic record of associated features such the housing built for the power station staff.

Links:

• Trawsfynydd Power Station Coflein entry.
• Trawsfynydd Power Station Grounds and Gardens Coflein entry.
• Magnox North’s website includes information about their plants, including videos of various stages of the demolition and a 3-d animation showing what the decommissioning involves.
• A biography of Dame Sylvia Crowe is on the website of the Landscape Institute.
• The archive of the architect, Sir Basil Spence is held at the Royal Commission on the Ancient and Historical Monuments of Scotland. The archive includes Spence’s concept sketches for Trawsfynydd.

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