trawsfynydd rpv inspection - nuclear congress 2013 poster presentation

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2. Scope: The inspection gathered photographic stills and video footage of a number of areas in and around the RPV and its primary circuits. Inspection requirements: To provide a comparison of the condition of the two reactor vessels in sufficient detail to allow detailed analysis of any degradation since the last inspection. To provide sufficient detail and records to establish a baseline to allow future comparisons to be made. To provide sufficient inspection and analysis to underpin the long term reactor buildings safety case. Inspection scope: From chargeface: 1.Vessel viewing hole survey between bioshield and RPV. 2.Standpipe channel assemblies survey of vessel internals. From -17’9” basement level: 3. Debris duct to R2 and to behind flange plate access only to R1 debris duct. 4. Cold gas ducts to R1 and R2. 5. Areas to reactor void to above and below floor pates and below RPV. Reactor Pressure Vessel Inspections at Trawsfynydd Nuclear Decommissioning Site Nick Brook Magnox Ltd, United Kingdom 3 2 5 4 1 3. Technical requirements: The inspections were undertaken using specialist camera systems and a small arm manipulator to the RPV and remote operated vehicles, including a pantograph, to other areas. Inspection equipment was commissioned off-site and inspection activities and techniques trialled and rehearsed. 1. Introduction: Trawsfynydd is situated in North Wales and will go into Care and Maintenance (C&M) in 2017. Inspection of Reactor Pressure Vessels (RPV) will provide information for C&M safety case. 5. Conclusions: Inspection was successful completed in July 2013. The inspection report and technical assessment that are required by the C&M safety case are on-going. Accident and incident free and completed within radiological dose budgets. Large amount of useful information was gathered. Mock-ups and rehearsals in the use of inspection equipment proved very effective and worthwhile. Positive feedback from ONR. Consistent legacy information management issues concerning the reliability, accuracy and availability and also archiving and indexing of records. Conflict between asbestos and ionising radiation regulations made definitive asbestos advice problematic. The inspection was largely self-performed using Asset Care contractor team and Magnox resource. This suited the iterative manner in which the works progressed and negated excessive set-up costs and contractor variations. Any downtime was mitigated by reallocating the resource onto other Asset Care activities. Detailed design and manufacture of the major items of inspection equipment was contracted to a local precision engineering company who proved extremely effective. Though not experienced in the nuclear industry design and quality assurance issues were managed through a strategy of careful concept specification, a collaborative approach and a design review process. 4. Implementation: The inspection was completed to all areas between November 2011 and July 2013 with the exception of the R1 reactor void. No serious corrosion issues were uncovered. Several items of interest, including displaced floor plates and detached aluminium cladding will require further investigation.

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Poster presentation given at 2013 Nuclear Congress conference, Manchester, of Trawfynydd reactor pressure vessel inspection.

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Page 1: Trawsfynydd RPV Inspection - Nuclear congress 2013 poster presentation

2. Scope: The inspection gathered photographic stills and video footage of a number of areas in

and around the RPV and its primary circuits.

Inspection requirements:To provide a comparison of the condition of the two reactor vessels in sufficient detail to allow detailed analysis of any degradation since the last inspection. To provide sufficient detail and records to establish a baseline to allow future comparisons to be made.To provide sufficient inspection and analysis to underpin the long term reactor buildings safety case.

Inspection scope:From chargeface:

1.Vessel viewing hole survey between bioshield and RPV.2.Standpipe channel assemblies survey of vessel internals.

From -17’9” basement level: 3. Debris duct to R2 and to behind flange plate access only to R1 debris duct. 4. Cold gas ducts to R1 and R2. 5. Areas to reactor void to above and below floor pates and below RPV.

Reactor Pressure Vessel Inspections at Trawsfynydd Nuclear Decommissioning Site

Nick BrookMagnox Ltd, United Kingdom

3

2

5 4

1

3. Technical requirements: The inspections were undertaken using specialist camera systems and a small

arm manipulator to the RPV and remote operated vehicles, including a pantograph, to other areas. Inspection equipment was commissioned off-site and inspection activities and techniques trialled and rehearsed.

1. Introduction: Trawsfynydd is situated in North

Wales and will go into Care and Maintenance (C&M) in 2017. Inspection of Reactor Pressure Vessels (RPV) will provide information for C&M safety case.

5. Conclusions: Inspection was successful completed in July 2013. The inspection report and technical assessment that are

required by the C&M safety case are on-going.Accident and incident free and completed within radiological dose budgets.Large amount of useful information was gathered. Mock-ups and rehearsals in the use of inspection equipment proved very effective and worthwhile.Positive feedback from ONR.Consistent legacy information management issues concerning the reliability, accuracy and availability and also archiving and indexing of records.Conflict between asbestos and ionising radiation regulations made definitive asbestos advice problematic.

The inspection was largely self-performed using Asset Care contractor team and Magnox resource. This suited the iterative manner in which the works progressed and negated excessive set-up costs and contractor variations. Any downtime was mitigated by reallocating the resource onto other Asset Care activities. Detailed design and manufacture of the major items of inspection equipment was contracted to a local precision engineering company who proved extremely effective. Though not experienced in the nuclear industry design and quality assurance issues were managed through a strategy of careful concept specification, a collaborative approach and a design review process.

4. Implementation: The inspection was completed to all areas between November 2011 and July 2013 with the exception of the R1

reactor void. No serious corrosion issues were uncovered. Several items of interest, including displaced floor plates and detached aluminium cladding will require further investigation.