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.

Planned inspection of Wylfa power station

Executive summary

Purpose of intervention

This was a planned inspection of Magnox Ltd’s Wylfa power station, undertaken as part of the planned intervention strategy for the Decommissioning, Fuel and Waste (DFW) Programme of the Office for Nuclear Regulation (ONR).

The work was carried out in line with the planned inspection programme contained in the Wylfa Integrated Intervention Strategy (IIS) and Magnox Ltd Corporate IIS.

Interventions Carried Out by ONR

Planned inspections of Licence Conditions, 7 (Incidents in site), 22 (Modification or experiment on existing plant) and 26 (Control and supervision of operations).

I discussed the following matters whilst on site:

Explanation of Judgement if Safety System Not Judged to be Adequate

No safety system based inspections were undertaken during this intervention.

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

The Licence Condition 7 inspection focussed on Magnox Ltd’s response to the two enforcement letters issued by ONR in November 2015 following two separate incidents at Wylfa. The inspection concluded that there is clear evidence that the site is actively pursuing further improvements beyond those identified from the immediate investigation actions and that implementation of arrangements is of a good standard, an IIS rating of 2 is assigned.

The Licence Condition 22 Inspection focussed on the implementation of the arrangements using a current Category 2 submission supporting the implementation of the Post Generation Defueling Safety Case. Whilst the arrangements for LC 22 remain adequate it is concluded that there are some procedural weaknesses in the Station Plant Modification Proposal meeting element of the site arrangements. Clarity of actions being placed by the meeting and evidence of their subsequent resolution prior to authorisation to implement modifications was of variable quality. Consequently and IIS rating of 4, below standard, is assigned.

The Licence Condition 26 inspection focussed on the current 100 day, post generation, outage. Control and supervision of the maintenance of the Reactor 1 Gas Circulators was sampled. There was positive engagement in improvement programmes and a good understanding of lead team expectations was evident at all levels. It is concluded that there are mature arrangements for control and supervision that are implemented to a good standard and an IIS rating of 2 is assigned.

I was satisfied with the content and conduct of the meetings where additional topical matters were discussed. These discussions are essential to understanding the future site plans and aspirations.

Conclusion of Intervention

From the information obtained and evidence gathered during this intervention, I do not believe there are any matters identified that have a significant negative effect on the system integrity and there were no issues identified that were considered to adversely affect nuclear safety.

Crynodeb gweithredol

Diben yr Ymyrraeth

Roedd hwn yn archwiliad a gynlluniwyd o orsaf bŵer Wylfa Magnox Ltd, a gyflawnwyd yn rhan o'r strategaeth ymyrraeth a gynllunnir ar gyfer Rhaglen Datgomisiynu, Tanwydd a Gwastraff (DFW) y Swyddfa dros Reoli Niwclear (ONR).

Cyflawnwyd y gwaith yn unol â'r rhaglen archwilio a gynlluniwyd yn Strategaeth Ymyrraeth Integredig (IIS) Wylfa a Magnox Ltd Corporate IIS.

Ymyraethau a Gyflawnwyd gan yr ONR

Archwiliadau a gynlluniwyd o Amodau Trwydded, 7 (Digwyddiadau ar y safle), 22 (Addasiad neu arbrawf ar y safle presennol) a 26 (Rheoli a goruchwylio gweithredu).

Trafodais y materion canlynol tra ar y safle:

Esboniad o’r Dyfarniad os Nad oedd y System Ddiogelwch wedi cael ei Barnu yn Ddigonol.

Ni chyflawnwyd archwiliadau seiliedig ar system ddiogelwch yn ystod yr ymyrraeth hon.

Casgliadau Allweddol, Barnau’r Arolygydd a Rhesymau dros Wneud Dyfarniadau

Roedd Amod Trwyddedu 7 yn ffocysu ar ymateb Magnox Ltd i'r ddau lythyr gorfodi a gyhoeddwyd gan yr ONR yn Nhachwedd 2015 yn dilyn dau ddigwyddiad unigol yn Wylfa. Casglodd yr archwiliad fod yna dystiolaeth glir fod y safle yn gwneud ymdrech i fynd ar drywydd gwelliannau pellach tu hwnt i'r rhai a nodwyd o gamau'r archwiliad uniongyrchol a bod gweithrediad trefniadau o safon dda, fe ddyrannir graddiad IIS o 2.

Roedd Amod Trwyddedu 22 yn ffocysu ar weithrediad y trefniadau yn defnyddio cyflwyniad Categori 2 cyfredol i gefnogi gweithrediad Achos Diogelwch Gwagio Tanwydd Wedi Cynhyrchu. Er bod y trefniadau ar gyfer LC 22 yn dal yn ddigonol, cesglir bod yna rai gwendidau gweithdrefnol o hyd yng Nghynnig Addasu Gwaith yr Orsaf o ran bodloni gofynion trefniadau'r safle. Roedd safon eglurder camau sy'n cael eu gosod gan y cyfarfod a thystiolaeth o'u datrysiad dilynol cyn awdurdodiad i weithredu addasiadau yn amrywiol. O ganlyniad, rhoddir sgôr IIS o 4, is na'r safon.

Roedd Amod Trwyddedu 26 yn ffocysu ar y diffoddiad 100 niwrnod cyfredol, yn dilyn cynhyrchu. Samplwyd rheolaeth a goruchwyliaeth o gynnal Cylchredwyr Nwy Adweithydd 1. Roedd yna ymgysylltu positif mewn rhaglenni gwelliant ac roedd dealltwriaeth dda o ddisgwyliadau'r tîm arweiniol yn amlwg ar bob lefel. Cesglir fod yna drefniadau aeddfed ar gyfer rheolaeth a goruchwylio a weithredir i safon dda ac fe ddyrannir graddiad IIS o 2.

Roeddwn yn hapus gyda chynnwys a chyflawniad y cyfarfodydd ble trafodwyd materion pynciau atodol. Mae'r trafodaethau hyn yn allweddol i ddeall cynlluniau a dyheadau ar gyfer y safle yn y dyfodol.

Casgliad yr Ymyrraeth

O'r wybodaeth a gaffaelwyd a thystiolaeth a gasglwyd yn ystod yr ymyrraeth hon, nid wyf yn credu bod yna unrhyw faterion a nodwyd sy'n cael effaith arwyddocaol ar gywirdeb y system ac ni nodwyd unrhyw faterion a ystyriwyd i fod yn effeithio'n andwyol ar ddiogelwch niwclear.