Office for Nuclear Regulation

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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 (LCs), 11, 23 and 24.

A reactive inspection was also undertaken by ONR Radiation Protection inspector into a personal contamination event, previously reported to ONR under the licensee’s arrangements for compliance with Licence Condition 7, “Incidents 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

This LC 23 and 24 inspections focussed on the procedures for change control of Approved Operating Rules (ORs), Referenced Station Operating Instructions (RSOIs) and Station Operating instructions (SOIs). This focus was considered to be appropriate to support the regulatory response to recent requests for amendments to Approved Operating Rules to enable site transition to defueling operations. The inspection found that the current site arrangements for change control of ORs, RSOIs and SOIs appear robust and commitments have been given to regulatory engagement for transition to revised arrangements following entry to defueling. Compliance with Licence Condition 23 and 24 is considered to be adequate and an IIS rating of 3 is assigned.

Wylfa Level 1 Demonstration Exercise “Alpha 16” was held on 23/3/2016. This exercise was a joint security and nuclear safety scenario designed to demonstrate the effectiveness of the proposed defueling emergency arrangements at Wylfa. The security aspects of the exercise were witnessed by two ONR Civil Nuclear Security (CNS) Inspectors and their observations are reported elsewhere. The safety element of the exercise was witnessed by four ONR safety inspectors, the Site inspector, Fire Safety Inspector, LMfS Inspector and Radiation Protection Inspector as part of a compliance inspection for LC 11. . The inspection highlighted many positive observations and some opportunities for improvement under ALARP were identified. A number of exercise management decisions disrupted some elements of the arrangements being successfully demonstrated. Consequently, ONR will require a redemonstration of some aspects of the exercise in the near future.  Despite some of the observations of opportunities for improvement it is concluded that the exercise provided an adequate demonstration of the Wylfa emergency arrangements and valuable learning has been captured to take forward into defueling. An IIS rating of 3 is assigned to this inspection.

An ONR Radiation Protection Specialist Inspector undertook a reactive inspection into the contamination event that was reported to ONR under LC7 arrangements. When opening a valve in blowdown filter room liquid spilled onto personnel and ladders in the working area. Subsequently the person was found have low levels of contamination on gloves and both knees. The inspection concluded that since Magnox Ltd’s main response to the event is communication and education it is important for ONR to follow this up in the near to medium term, to allow judgements to be made as to how effective this approach has been.

Conclusion of Intervention

From the information obtained and evidence gathered during this intervention, I believe there were no issues identified that were considered to adversely affect nuclear safety.


Crynodeb gweithredol

Diben yr Ymyrraeth

Roedd hwn yn arolygiad cynllunedig o orsaf bŵer Magnox Cyf yn Wylfa, a wnaed fel rhan o’r strategaeth ymyriad cynllunedig ar gyfer Rhaglen Ddatgomisiynu, Tanwydd a Gwastraff (DFW) y Swyddfa dros Reoli Niwclear (ONR).

Gwnaed y gwaith yn unol â’r rhaglen arolygiad cynllunedig a gynhwysir yn Strategaeth Ymyriad Integredig Wylfa (IIS) ac IIS Corfforaethol Magnox Cyf.

Ymyriadau a Wnaed gan ONR

Arolygiadau cynllunedig o Amodau Trwydded (LCs), 11, 23 a 24.

Hefyd gwnaed arolygiad adweithiol gan arolygydd Diogelwch Ymbelydredd ONR i ddigwyddiad halogi personol, a adroddwyd yn flaenorol wrth ONR o dan drefniadau’r trwyddedai ar gyfer cydymffurfio ag Amod Trwydded 7, “Digwyddiadau ar y Safle”.

Esboniad o’r Dyfarniad os na Ddyfarnir bod y System Ddiogelwch yn Ddigonol

Ni wnaed unrhyw arolygiadau seiliedig ar system ddiogelwch yn ystod yr ymyriad hwn.

Canfyddiadau Allweddol, Barnau’r Arolygydd a Rhesymau am Ddyfarniadau a Wnaed

Fe wnaeth yr arolygiadau LC 23 a 24 hyn ganolbwyntio ar y gweithdrefnau ar gyfer newid rheolaeth Rheolau Gweithredu Cymeradwy (ORs), Cyfarwyddiadau Gweithredu Gofynnol yr Orsaf (RSOIs) a Chyfarwyddiadau Gweithredu’r Orsaf (SOIs). Ystyriwyd bod y ffocws hwn yn briodol i gefnogi’r ymateb reoleiddiol i geisiadau diweddar am ddiwygiadau i Reolau Gweithredu Cymeradwy er mwyn galluogi i’r safle bontio i weithrediadau datlenwi tanwydd. Fe wnaeth yr arolygiad ganfod bod y trefniadau cyfredol ar gyfer newid rheolaeth o ORs, RSOIs ac SOIs yn ymddangos yn gadarn a rhoddwyd ymrwymiadau i ymgysylltu rheoleiddiol ar gyfer pontio i drefniadau adolygedig yn dilyn dechrau datlenwi tanwydd. Ystyrir bod cydymffurfiad ag Amod Trwydded 23 a 24 yn ddigonol a rhoddir mesur IIS o 3.

Cynhaliwyd Ymarfer Arddangos Lefel 1 Wylfa “Alpha 16” ar 23/3/2016. Roedd yr ymarfer hon yn senario diogeledd a diogelwch niwclear ar y cyd a gynlluniwyd i arddangos effeithiolrwydd y trefniadau argyfwng datlenwi tanwydd arfaethedig yn Wylfa. Tystiwyd yr agweddau diogeledd ar yr ymarfer gan ddau Arolygydd Diogeledd Niwclear Sifil ONR (CNS) a chyflwynir eu sylwadau mewn man arall. Tystiwyd yr agwedd ddiogelwch ar yr ymarfer gan bedwar arolygydd diogelwch ONR, yr Arolygydd Safle, yr Arolygydd Diogelwch Tân, yr Arolygydd LMfS  a’r Arolygydd Diogelwch Ymbelydredd fel rhan o arolygiad cydymffurfiad ar gyfer LC 11. Fe wnaeth yr arolygiad amlygu llawer o sylwadau positif ac nodwyd rhai cyfleoedd ar gyfer gwella o dan ALARP. Fe wnaeth nifer o benderfyniadau ynghylch rheoli’r ymarfer amharu ar y broses o arddangos rhai elfennau o’r trefniadau’n llwyddiannus. O ganlyniad, bydd ONR angen ail arddangosiad o rai agweddau ar yr ymarfer yn y dyfodol agos. Er gwaethaf rhai o’r sylwadau ar gyfleoedd ar gyfer gwella cesglir bod yr ymarfer wedi darparu arddangosiad digonol o’r trefniadau argyfwng yn Wylfa a chipiwyd gwersi gwerthfawr i’w symud ymlaen i’r broses o ddatlenwi tanwydd. Rhoddir mesur IIS o 3 i’r arolygiad hwn.

Fe wnaeth Arolygydd Arbenigol Diogelwch Ymbelydredd ONR ymgymryd ag arolygiad adweithiol i’r digwyddiad halogi a adroddwyd wrth ONR o dan drefniadau LC7. Wrth agor falf mewn ystafell hidlo chwythu-i-lawr fe wnaeth hylif orlifo ar bersonél ac ysgolion yn yr ardal weithio. Wedyn canfuwyd bod gan y berson lefelau isel o halogiad ar fenig a’r ddwy ben-lin. Fe wnaeth yr arolygiad gasglu, gan fod prif ymateb Magnox Cyf i’r digwyddiad yw cyfathrebu ac addysgu, mae’n bwysig i ONR ddilyn hyn yn y tymor byr neu’r tymor canolig, er mwyn caniatáu i ddyfarniadau gael eu gwneud ynghylch pa mor effeithiol mae’r ymagwedd hon wedi bod.

Casgliad yr Ymyriad

O’r wybodaeth a gafwyd a’r dystiolaeth a gasglwyd yn ystod yr ymyriad hwn, credaf na nodwyd unrhyw broblemau yr ystyriwyd eu bod yn effeithio’n niweidiol ar ddiogelwch niwclear.