Office for Nuclear Regulation

This website uses non-intrusive cookies to improve your user experience. You can visit our cookie privacy page for more information.

Wylfa System Based Inspection of the Defuelling Route

Executive summary

Purpose of Intervention

The purpose of this inspection, one of a series of planned inspections at Wylfa, was to carry out system based inspection (SBI) of the defuelling route to consider the adequacy of implementation of the licensee's safety case claims in respect of this plant.

Interventions Carried Out by ONR

We carried out a two day on-site SBI of the Wylfa defuelling route together with the licensee's Welsh region internal regulation inspector. This inspection comprised of reviewing in advance relevant documents, on-site discussions with station staff, a plant inspection and sampling plant records and other relevant documentation.

As part of my inspection I examined evidence for the adequate implementation of five licence conditions (LC). The LCs have been selected in view of their importance to nuclear safety and are defined within ONR's process for SBI. They are: LC 10 (training), LC 23 (operating rules), LC 24 (operating instructions), LC 27 (safety mechanisms, devices and circuits), LC 28 (examination, inspection, maintenance and testing) and LC 34 (leakage and escape of radioactive materials and waste).

We also received an update on defuelling operations on site and an update on the activities of Magnox Limited's internal regulator.

Explanation of Judgement if Safety System Not Judged to be Adequate

We judged this safety system to be adequate.

Key Findings, Inspector's Opinions and Reasons for Judgements Made

From the evidence examined by me during this inspection, I consider that the licensee has adequately implemented those claims within the post generation defuelling safety case that relate to the defuelling route.

I made a number of minor observations during my inspection. These were shared with, and accepted by, the licensee during my inspection feedback. None of these adversely affect safety. Overall, I did not identify any significant shortfalls in the delivery of safety functions or compliance with LC arrangements.

In the course of my inspection I did not identify any significant concerns with the adequacy of the licensee's safety case for this system that would necessitate further assessment by ONR.

In my opinion defuelling issues on site continue to challenge removal of fuel from site before cessation of reprocessing operations at Sellafield. Defuelling will continue to form part of my routine interactions with site.

Conclusion of Intervention

From the evidence examined, we judged that the licensee has adequately implemented the relevant claims within its safety case. We were satisfied that the arrangements for all the Licence Conditions against which we inspected are being implemented adequately. I made a number of minor observations during my inspection, which were accepted by the licensee.


Pwrpas yr Ymyrraeth

Pwrpas yr arolygiad hwn, un o gyfres o arolygiadau a gynlluniwyd yn Wylfa, oedd cynnal arolygiad seiliedig ar system (SBI) o'r llwybr datlenwi i ystyried digonolrwydd gweithredu hawliadau achos diogelwch y trwyddedai mewn cysylltiad â'r gwaith hwn.

Ymyriadau a Wnaed gan ONR

Fe wnaethom gynnal SBI deuddydd ar y safle o lwybr datlenwi Wylfa ynghyd ag arolygydd rheoleiddio mewnol rhanbarth Cymru'r trwyddedai. Roedd yr arolygiad hwn yn cynnwys adolygu dogfennau perthnasol ymlaen llaw, trafodaethau ar y safle â staff yr orsaf, arolygiad o'r gwaith a chofnodion samplo'r gwaith a dogfennau perthnasol eraill.

Fel rhan o'm arolygiad, archwiliais dystiolaeth ar gyfer gweithredu pum amod trwydded (LC) yn ddigonol. Mae'r LCs wedi'u dewis oherwydd eu pwysigrwydd i ddiogelwch niwclear ac fe'u diffinnir yn y broses ONR ar gyfer SBI. Y rhain yw: LC 10 (hyfforddiant), LC 23 (rheolau gweithredu), LC 24 (cyfarwyddiadau gweithredu), LC 27 (mecanweithiau, dyfeisiadau a chylchedau diogelwch), LC 28 (archwilio, arolygu, cynnal a chadw a phrofi) ac LC 34 (deunyddiau a gwastraff ymbelydrol yn gollwng a dianc).

Fe wnaethom hefyd dderbyn diweddariad ar weithrediadau datlenwi ar y safle a diweddariad ar weithgareddau rheoleiddiwr mewnol Magnox Cyfyngedig.

Esboniad o'r Dyfarniad os Na Ddyfernir bod y System Ddiogelwch yn Ddigonol

Fe wnaethom farnu bod y system ddiogelwch hon yn ddigonol.

Canfyddiadau allweddol, Barnau'r Arolygydd a Rhesymau am Ddyfarniadau a Wnaed

O'r dystiolaeth a archwiliwyd gennyf yn ystod yr arolygiad hwn, credaf fod y trwyddedai wedi gweithredu'r honiadau hynny'n ddigonol o fewn yr achos diogelwch datlenwi ôl-genhedlaeth sy'n gysylltiedig â'r llwybr datlenwi.

Fe wnes i nifer o fân sylwadau yn ystod fy arolygiad. Rhannwyd y rhain gyda, ac fe'u derbyniwyd gan, y trwyddedai yn ystod fy adborth arolygiad. Nid yw unrhyw un o'r rhain yn effeithio'n andwyol ar ddiogelwch. At ei gilydd, ni wnes i nodi unrhyw ddiffygion arwyddocaol wrth gyflenwi swyddogaethau diogelwch neu gydymffurfiaeth â threfniadau LC.

Yn ystod fy arolygiad, ni wnes i nodi unrhyw bryderon arwyddocaol ynghylch digonolrwydd achos diogelwch y trwyddedai ar gyfer y system hon a fyddai'n golygu bod angen asesiad pellach gan ONR.

Yn fy marn i, mae materion datlenwi ar y safle yn parhau i herio symud tanwydd o'r safle cyn rhoi'r gorau i weithrediadau ailbrosesu yn Sellafield. Bydd datlenwi'n parhau i fod yn rhan o'm rhyngweithiadau arferol gyda'r safle.

Casgliad yr Ymyrraeth

O'r dystiolaeth a archwiliwyd, fe wnaethom farnu bod y trwyddedai wedi gweithredu'r honiadau perthnasol yn ddigonol o fewn ei achos diogelwch. Roeddem yn fodlon bod y trefniadau ar gyfer yr holl Amodau Trwydded roeddem yn arolygu yn eu hôl yn cael eu gweithredu'n ddigonol. Fe wnes i nifer o fân sylwadau yn ystod fy arolygiad, a dderbyniwyd gan y trwyddedai.