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Wylfa Cable & Civil Works 132kV

Excalon Ltd was appointed by Iberdrola Engineering and Construction to manage and install approximately 6km of 132kV double circuit ducting infrastructure from the existing Nuclear Power Station Site at Wylfa to new terminal tower locations.

Scope of Works

Horizon Nuclear Power were carrying out significant construction works adjacent to the existing nuclear site at Wylfa in order to facilitate the upcoming first planned UK modular reactor. The two existing SPEN 132kV cables which form part of the two 132kV transformer feeder circuits out of Wylfa to Amlwch and Caergeiliog pass through the proposed site. The circuits therefore were required to be diverted to an alternative designated route.

The new cable corridor was designed to accommodate the above circuits and also the future installation of two additional NGET 132kV circuits. On completion, the redundant fluid filled circuits will be removed & decommissioned.

Services Provided

> De-stumping and removal of trees.
> Demolition and site clearance.
> Ground investigation
> Earthworks and general excavation
> Installation of ductwork
> Installation of fibre chambers
> Brook crossings
> Heavy duty road crossings
> Directional Drilling
> Timber post and rail fencing and metal field gate installation.
> Install haul roads as part of enabling works and cable corridor boundary.
> HVCA Testing
> Reinstatement

Technical Scope

> Design and excavation of 132kV joint bays
> Installation of new 132kV 1200sqmm XLPe cables.
> Provision of 132kV jointing resource
> Design and installation of new CSE structures
> Removal and de-oiling of redundant CSEs
> Excavation and removal of redundant cables
> HVAC testing
> Installation of new busbars and connections

Our highly experienced management team coordinated the installation in close collaboration with IEC as well as the other key stakeholders Horizon Nuclear Power, Magnox, National Grid and Anglesey Council. A key component to the successful delivery was our ability to utilise our inhouse customer services department and traffic management division.

The Project included the design and installation of a twin trefoil configuration though private land and highways as well as the installation of 1km haul road, fibre network, Directional Drill, Timber Heading and archaeological watching briefs.

Excalon were contracted by General Cable for the installation of the 1200m2 132kV cable for the new Amlwch and Caergilliog circuits. Each of the circuits were installed by one of Excalon’s specialist EHV cable teams through ducts, using our bespoke cable trailer and installation equipment.

Cable ends were installed and cleated up 132kV terminal poles, which included the design and fabrication of new steel work structures. Cables were installed and terminated in an indoor 132kV switch room inside the existing Wylfa Grid GIS Substation. Due to the confined restricted working area, this procedure required specific temporary works design and method statements for the use of indoor cranes and civil works.

Excalon’s Jointers and engineers completed the 132kV jointing works and HVAC testing to commission the circuits, working under the technical specification procedures and supervision of the cable manufacturer. Including the installation of cross bonding earthing.

Under the supervision of ecologist and archaeological watching briefs, the existing old filled 132kV circuits were flushed, excavated and removed throughout the site to allow the new construction work to begin.

Download Case Study – 132kV Wylfa