On-ground and relocatable counter-terror fencing originally designed to meet stringent security requirements for the many varied London 2012 Olympic venues is now being deployed to protect nuclear construction sites. With ‘no dig’ policies becoming the norm for sensitive sites like nuclear construction and logistics centres, the fencing system offers the same level of security as equivalent in-ground systems and is effective on soft undulating rural grassland as well as hard urban surfaces.
Developed by Blok ‘N’ Mesh Global Ltd, the design features ‘BNM’ concrete blocks that secure 358 prison weld-mesh in place. The modular system requires no ground excavation and is relocatable as required. Each 750 kg block includes integral fork lift slots to enable safer handling, and a central lifting pin recessed in the top which provides a facility to lift from above which assists when installers are faced with restricted manoeuvrability along the fence line. The kentledge blocks used for the fence have a 120-year design life and development has seen considerable efforts being undertaken with regards to environmental concerns. The 50 Newton concrete block is manufactured using 60% quarry dust (an industrial by-product) to minimise environmental impact and does not contain reinforcement – making it much simpler to recycle.
Part of a family-owned group of British companies founded in 1969, the Blok ‘N’ Mesh POLMIL® range of temporary fencing offers a number of benefits to nuclear facilities, including time saving deployment. From the point of identifying a project need for security fencing, there are multiple administrative procedures and assessments, by a wide range of different specialists, that have to be completed before installers can start digging post holes in the ground at nuclear facilities. These assessments cover concerns such as risk to underground services (existing and planned), environmental hazards (existing ground contamination, safe spoil disposal, making good when fence removed) and future site changes when the fence line needs to be moved as the construction/decommissioning progresses. By the time all stakeholders have completed approvals, the very reason for the fence being required in the first place can be delayed as a result of the security fence not being in position by the planned project start date. The approvals required before installing on-ground relocatable security fencing are significantly less demanding and time consuming than those with post-in-ground.
By reducing the number of administrative processes, meetings and expert assessments necessary before approval for on-ground fencing provide a significant cost saving in man hours over traditional in-ground systems. If circumstances change – as they often do – on-ground fencing is quick and easy to relocate, and 100% reusable, making it flexible and sustainable. Furthermore, on-ground security fencing carries less associated risk than in-ground equivalents. However, whilst using on-ground fencing reduces risk for the installers, it must also achieve at least the same level of security as the comparative post-in-ground alternative.
Nuclear deployment
A trial at Sizewell B in 2014 utilised Blok N Mesh systems as part of an upgrading programme to their existing fence line. The contractors used 100 linear metres of POLMIL® BASE level fence to protect the section of permanent fencing they were working on.
The relocatable fence was simply moved along the existing line as the work progressed. This ensured the site maintained the appropriate level of security for the period that each section of permanent fence was compromised.
The fencing has now been deployed to 17 different Nuclear Licensed Sites in the UK and France – many of which have had multiple deployments during the past decade. Having repeatedly utilised the on-ground fencing since 2014, EDF have built up considerable experience and confidence in using the fencing and have recently acquired the same design to protect both the Temporary Construction Area (TCA) and Main Construction Area (MCA) at Sizewell C.
Following initial trials at EDF’s Sizewell B and for longer periods at the Hinkley Point C power stations, a challenge associated with nuclear site deployments emerged as the highly corrosive atmospheric conditions that are a constant feature at these exposed coastal locations. The company subsequently developed a hot dipped galvanised after manufacture finish option for the fencing in order to significantly extend the working life of all major steel components exposed to such harsh environments.
Following deployments at the London Olympics, the Glasgow 2014 Commonwealth Games, and 4km deployment to protect a remote mining operation in Greece – which has stood up to some extremely violent activity, including ram-raids and hostile crowds of up to 300 persons trying to pull fencing and gates down – in early 2024 when Sellafield also selected Blok N Mesh for a significant run of fencing which included sections that required a minimal footprint to maximum the work area, or continued across permanent hard surface areas.
An evolving design
Blok N Mesh has continued testing and evolving the technology at their Merseyside factory. Independently assessed by the Centre for Protection of National Infrastructure (CPNI), specific testing has also included long-term installations in harsh weather environment to confirm it has the ability to reliably host microphonic perimeter intruder detection systems (PIDS) as well as specialist forces attack, hostile vehicle ramming and coordinated ‘mob’ attacks.
More recently, a means of access through the fence line for ‘monster machines’ such as the 110 tonne dump trucks commonly used for mining operations and nuclear new build sites was identified and a heavy duty 3m high x 10m opening on-ground gate introduced. These gates are completely surface mounted and highly tolerant of different ground conditions while bi-folding leafs minimise the swing radius to allow safer operation and are less vulnerable to being damaged when open. Multi-adjustable hinges and unique locking mechanisms are designed to remain operational even when heavy vibration or ground movement cause the repositioning of one gate leaf relative to another over time.
On-ground temporary security fence systems offer many advantages over traditional post-in-ground fencing and having come to the attention of the nuclear industry, their deployment is proving the utility of modular movable fencing. As nuclear development shits to a new accelerated development phase, simple security that can be quickly deployed is another tool in the move towards more streamlined operations.
