Magnox: Optioneering for ILW Encapsulation Within the Berkeley Caesium Removal Plant



Reduction in processing costs

Massively reduced timescales

The best concept down selected

SUMMARY

We were tasked to carry out optioneering to investigate the feasibility of installing a TILWSP type system within the CRP at Berkley Power Station. In 20 weeks (a fraction of the time and cost of a usual civil nuclear project), we successfully took the completed concept through the scrutiny of HAZID, HAZOP I and HAZOP II and supported them with the 3D models and Mechanical Sequence Diagrams, a 2D drawing pack and costings.

SITUATION

Berkeley Power Station is located on the eastern bank of the River Severn in Gloucestershire; after 27 years of operation, it is now in a decommissioning phase. The site is one of 12 managed by Magnox Ltd on behalf of the Nuclear Decommissioning Authority (NDA) with Magnox taking responsibility for the stations’ full lifecycles – from operation, through defueling and into decommissioning.

Within the Berkeley site, there are multiple structures and facilities undergoing decommissioning. One of these structures, the Caesium Removal Plant (CRP) provided numerous challenges and opportunities during its decommissioning phase.

Firstly, the irradiated materials produced as a consequence of its primary use needed to be removed and the various post-operative clean out (POCO) activities conducted. This was applicable to the contents of sand pressure filters, settling and delay tanks and stored Aloxite and Desiccant amongst others.

Secondly, the CRP was being used as a shielded storage area for pond sludge contained in 200-litre drums and these needed to be removed and taken through a processing operation.

Thirdly, it was recognised that the CRP could fulfil the role of providing shielding to certain waste processing operations; in effect providing the capability of the Transportable Intermediate Level Waste Solidification Plant (TILWSP) that was being used at Wylfa but with the processing equipment integrated within the existing building.

CHALLENGE

As noted, the CRP building provided the basis of many individual tasks, each of which could be elaborated upon at length. This case study will focus upon the optioneering conducted to investigate the feasibility of installing a TILWSP type system within the CRP; the structural modifications required to achieve that aim, the CAPEX costs and the preliminary workflow for the waste immobilisation process.

 The ultimate aim of the facility was to take Intermediate Level Waste (ILW), such as the pond sludge, and safely decant it from the 200L drums into a container suitable for off-site long-term storage, for example in a geological storage facility. The container would typically consist of a large bespoke stainless-steel drum and bolted lid incorporating a ‘lost-paddle’, possibly with a concrete overpack. Within the drum, the irradiated waste would be encapsulated within a cementitious grout, using the paddle to help create an homogeneous mixture and hence avoiding radioactivity hotspots. This, plus the inability to leak or spill will improve the package safety over the storage period.

SOLUTION

We undertook a whole range of tasks to develop the solidification plant concept from a blank sheet of paper through to a conceptually engineered and costed solution.

We started by surveying the CRP building to verify that the drawing pack represented the current condition. Our team then set about developing a 3D CAD database using PTC Creo; this consisted of parametric models of the buildings and each item of equipment. The use of Creo allowed us to benefit not only from the parametric modelling but also clash detection, fly-throughs, rendered images and provided a drawing platform to generate Mechanical Sequence Diagrams (MSDs) and the like.

Initial concepts for the plant were developed in hand sketch and basic model form, before undertaking a formal review with the Magnox team and using Analytical Hierarchy Process (AHP) as a structured means to decide which concept best met the projects’ criteria of importance.

The chosen concept was then further developed through detailed structural modelling, to generate the required points of access and internal process flow, this being underpinned by calculations for floor and wall capacities and even through the simulation of remote dismantling activities using a Brokk.

Once the structural modifications were planned, then we began to incorporate commercial off the shelf (COTS) equipment from the likes of Gantrail, Demag and Kuka Robotics to provide translation, lifting and de-lidding capabilities respectively. A preliminary grout plant was specified, and a waste addition and mixing head concept developed, additionally a COTS ‘tented import and export bay’ was specified to provide a buffer store for empty and full waste packages.

We successfully took the completed concept through the scrutiny of HAZID, HAZOP I and HAZOP II and supported these with the 3D models and Mechanical Sequence Diagrams. Finally, a 2D drawing pack and costing were produced, and we reached the end of a busy 20-week period!

BENEFITS
  • By re-using the shielding capacity and space afforded by the CRP, Magnox was able to reduce the costs associated with the processing of the ILW.
  • Our responsiveness and efficiency allowed us to complete the task in 20 weeks – a fraction of the typical timeline and cost for a civil nuclear project.
  • By applying the analytical hierarchy process (AHP), we ensured that the best concept was down-selected and developed – rather than the concept with the loudest sponsor! AHP also provided Magnox with full traceability of the decisions made and would underpin any future audits and allow future changes to be compared in a consistent manner.


We were tasked to carry out optioneering to investigate the feasibility of installing a TILWSP type system within the CRP at Berkley Power Station. In 20 weeks (a fraction of the time and cost of a usual civil nuclear project), we successfully took the completed concept through the scrutiny of HAZID, HAZOP I and HAZOP II and supported them with the 3D models and Mechanical Sequence Diagrams, a 2D drawing pack and costings.



Berkeley Power Station is located on the eastern bank of the River Severn in Gloucestershire; after 27 years of operation, it is now in a decommissioning phase. The site is one of 12 managed by Magnox Ltd on behalf of the Nuclear Decommissioning Authority (NDA) with Magnox taking responsibility for the stations’ full lifecycles – from operation, through defueling and into decommissioning.

Within the Berkeley site, there are multiple structures and facilities undergoing decommissioning. One of these structures, the Caesium Removal Plant (CRP) provided numerous challenges and opportunities during its decommissioning phase.

Firstly, the irradiated materials produced as a consequence of its primary use needed to be removed and the various post-operative clean out (POCO) activities conducted. This was applicable to the contents of sand pressure filters, settling and delay tanks and stored Aloxite and Desiccant amongst others.

Secondly, the CRP was being used as a shielded storage area for pond sludge contained in 200-litre drums and these needed to be removed and taken through a processing operation.

Thirdly, it was recognised that the CRP could fulfil the role of providing shielding to certain waste processing operations; in effect providing the capability of the Transportable Intermediate Level Waste Solidification Plant (TILWSP) that was being used at Wylfa but with the processing equipment integrated within the existing building.



As noted, the CRP building provided the basis of many individual tasks, each of which could be elaborated upon at length. This case study will focus upon the optioneering conducted to investigate the feasibility of installing a TILWSP type system within the CRP; the structural modifications required to achieve that aim, the CAPEX costs and the preliminary workflow for the waste immobilisation process.

 The ultimate aim of the facility was to take Intermediate Level Waste (ILW), such as the pond sludge, and safely decant it from the 200L drums into a container suitable for off-site long-term storage, for example in a geological storage facility. The container would typically consist of a large bespoke stainless-steel drum and bolted lid incorporating a ‘lost-paddle’, possibly with a concrete overpack. Within the drum, the irradiated waste would be encapsulated within a cementitious grout, using the paddle to help create an homogeneous mixture and hence avoiding radioactivity hotspots. This, plus the inability to leak or spill will improve the package safety over the storage period.



We undertook a whole range of tasks to develop the solidification plant concept from a blank sheet of paper through to a conceptually engineered and costed solution.

We started by surveying the CRP building to verify that the drawing pack represented the current condition. Our team then set about developing a 3D CAD database using PTC Creo; this consisted of parametric models of the buildings and each item of equipment. The use of Creo allowed us to benefit not only from the parametric modelling but also clash detection, fly-throughs, rendered images and provided a drawing platform to generate Mechanical Sequence Diagrams (MSDs) and the like.

Initial concepts for the plant were developed in hand sketch and basic model form, before undertaking a formal review with the Magnox team and using Analytical Hierarchy Process (AHP) as a structured means to decide which concept best met the projects’ criteria of importance.

The chosen concept was then further developed through detailed structural modelling, to generate the required points of access and internal process flow, this being underpinned by calculations for floor and wall capacities and even through the simulation of remote dismantling activities using a Brokk.

Once the structural modifications were planned, then we began to incorporate commercial off the shelf (COTS) equipment from the likes of Gantrail, Demag and Kuka Robotics to provide translation, lifting and de-lidding capabilities respectively. A preliminary grout plant was specified, and a waste addition and mixing head concept developed, additionally a COTS ‘tented import and export bay’ was specified to provide a buffer store for empty and full waste packages.

We successfully took the completed concept through the scrutiny of HAZID, HAZOP I and HAZOP II and supported these with the 3D models and Mechanical Sequence Diagrams. Finally, a 2D drawing pack and costing were produced, and we reached the end of a busy 20-week period!



  • By re-using the shielding capacity and space afforded by the CRP, Magnox was able to reduce the costs associated with the processing of the ILW.
  • Our responsiveness and efficiency allowed us to complete the task in 20 weeks – a fraction of the typical timeline and cost for a civil nuclear project.
  • By applying the analytical hierarchy process (AHP), we ensured that the best concept was down-selected and developed – rather than the concept with the loudest sponsor! AHP also provided Magnox with full traceability of the decisions made and would underpin any future audits and allow future changes to be compared in a consistent manner.
CRP Annotated Model
CRP Detail
CRP TIEB
CRP Model
TIEB eye level

SECTOR

PROJECT ATTRIBUTES

ANSYS CFD

MathCAD Calculations

3D CAD

Analytical Hierarchy Protocol (AHP) Decision Making

Optioneering

Process Animation


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