Office for Nuclear Regulation

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Wylfa Level 1 Emergency Arrangements demonstration, SBI and visit from ONR CNI and CEO

Executive summary

Purpose of Intervention

This inspection was one of a series of planned inspections for 2018/19, which are informed by the Office for Nuclear Regulation’s (ONR) Decommissioning Fuel and Waste (DFW) sub-division strategy.   

Interventions Carried Out by ONR

I undertook this inspection to examine the adequacy of the Magnox Limited  arrangements and their implementation on the Wylfa site for compliance with Licence Conditions (LC); LC 11 (emergency arrangements). I also undertook a system based inspection (SBI) of the Wylfa fuel-free verification programme.

For LC 11, two ONR safety and two ONR security inspectors and I observed the Wylfa Level 1 emergency arrangements demonstration.  Exercise Bravo 18 was a combined safety and security demonstration of the site’s emergency arrangements.

My SBI focused on ML’s programme for verifying that Wylfa site will be fuel-free on completion of defuelling operations. I specifically focused on the two reactors.  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).

I also received updates on; Wylfa organisational transition; land interactions with Horizon Nuclear Power Ltd.; re-baselined post-defuelling safety case.

I accompanied the ONR Chief Nuclear Inspector and Chief Executive Officer on their planned visit to Wylfa that took place on 19th October.

Explanation of Judgement if Safety System Not Judged to be Adequate

I judged this safety system to be adequate.

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

Based on our observations of emergency exercise demonstration Bravo18 we judged that Magnox Limited is effectively implementing arrangements for complying with LC 11 at Wylfa.  We identified a number of areas of good practice and areas where Magnox Limited could improve.

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 fuel-free verification of the reactors.

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.    

Conclusion of Intervention

I identified no matters that in my opinion could adversely affect nuclear safety.  My findings were shared with and accepted by the licensee.


Pwrpas yr Ymyriad

Roedd yr archwiliad hwn yn un o gyfres o archwiliadau a gynlluniwyd ar gyfer  2018/19, wedi’u hysbysu gan isddosbarthiad strategaeth DFW – Digomisiynu Tanwydd a Gwastraff y Swyddfa dros Reoli Niwclear (ONR).

Ymyriadau a gynhaliwyd gan ONR

Ymgymerais â’r archwiliad hwn i archwilio digonolrwydd trefniadau Magnox Limited  a’u gweithrediadau ar safle’r Wylfa ynghylch cydymffurfio ag Amodau Trwydded (LC); LC 11 (trefniadau argyfwng). Roeddwn hefyd wedi gwneud archwiliad ar sail system (SBI) o wirio rhaglen dim-tanwydd Wylfa.

Ar gyfer LC 11, roedd dau arolygwr diogelwch ONR a dau arolygwr amddiffyn ONR a minnau wedi gwylio arddangosiad trefniadau argyfwng Wylfa Lefel 1. Roedd Ymarferiad Bravo 18 yn gyfuniad o arddangosiad diogelwch ac amddiffyn o drefniadau argyfwng y safle.

Roedd fy SBI i wedi canolbwyntio ar raglen ML i wirio y bydd safle Wylfa yn rhydd o danwydd ar derfyn y gweithgareddau cael gwared ar danwydd. Roeddwn wedi canolbwyntio’n benodol ar y ddau adweithydd. Bum yn archwilio tystiolaeth ynghylch cyflawni’r pump amod trwydded (LC). Mae’r Amodau Trwydded wedi eu dewis ar sail eu pwysigrwydd i ddiogelwch niwclear ac wedi eu diffinio o fewn prosesau’r ONR ar  gyfer SBI. Dyma hwy: LC 10 (hyfforddi), LC 23 (rheolau gweithredu), LC 24 (cyfarwyddiadau gweithredu), LC 27 (diogelwch mecanweithiau, dyfeisiau a chylchedau), LC 28 (archwiliad, arolygiad, cynnal chadw a phrofi) ac LC 34 (gollyngiadau a deunyddiau ymbelydrol a gwastraff yn dianc).

Roeddwn hefyd wedi derbyn diweddariadau ar: drawsnewid cyfundrefnol Wylfa; rhyngweithiadau gyda chwmni Horizon Nuclear Power Ltd; achos ail-osod safon ar ôl cael gwared ar y tanwydd.  

Roeddwn wedi ymweld â’r Wylfa gyda Phrif Arolygydd Niwclear ONR a’r Prif Weithredwr ar 19ydd o Hydref.

Eglurhad am y Farn os Tybir Nad yw’r System Ddiogelwch yn Ddigonol

Rwyf o’r farn bod y system ddiogelwch hon yn ddigonol.

Prif Ganfyddiadau, Barn yr Arolygydd a Rhesymau dros y Farn Honno

Ar sail yr hyn a welsom yn arddangosiad ymarfer argyfwng Bravo18 roeddem o’r farn bod Magnox Limited yn gweithredu’r trefniadau ar gyfer cydymffurfio’n effeithlon ag LC 11 yn Wylfa.  Nodwyd sawl maes sy’n enghreifftiau o arfer da a mân feysydd lle gall Magnox Limited wella. 

Ar sail y dystiolaeth a archwiliwyd gennyf yn ystod yr archwiliad hwn, rwyf o’r farn bod y deiliad trwydded wedi gweithredu yn ddigonol yr hawliadau diogelwch hynny o fewn achos y genhedlaeth sy’n berthnasol i wiriad dim-tanwydd yr adweithyddion.

Nodais sawl pwynt mân yn ystod fy archwiliad. Rhannwyd y rhain a’u derbyn gan y deiliad trwydded yn fy adborth yn dilyn fy archwiliad. Nid oedd yr un ohonynt yn effeithio’n andwyol ar ddiogelwch. Yn gyffredinol, nid oeddwn wedi nodi unrhyw fethiannau arwyddocaol yn eu darpariaeth o weithredu diogelwch na chydymffurfedd â threfniadau LC.  

Casgliad yr Ymyriad

Ni ddynodais unrhyw fater a fedrai, yn fy marn i, gael effaith andwyol ar ddiogelwch niwclear. Rhannwyd a derbyniwyd fy nghanfyddiadau gan y deiliad trwydded.