Nuclear Operations

Pam Reddish | 02 January, 2026

A Heidelberg Materials concrete truckmixer

First published in the December 2025 issue of Quarry Management

Heidelberg Materials lead UK production of nuclear-grade concrete

Heidelberg Materials are the only heavy building materials manufacturer in the UK certified to produce nuclear-grade concrete in accordance with BS EN ISO 19443. The accreditation puts the company in a unique position to capitalize on the growing nuclear new-build market, as Sean Hunter, head of nuclear operations at Heidelberg Materials UK, explains.

The UK Government has reinforced its manifesto commitment to build more nuclear power plants to achieve energy security, and the latest evidence of this came in early November when Sizewell C reached financial close. Among its plans are to open up more new sites by including new nuclear technologies such as small and advanced modular reactors, which can be built at a greater variety of locations while still adhering to robust criteria.

Building nuclear power plants is technically demanding and requires consistent delivery of the highest-quality building materials in significant volumes over an extended period, meaning the role of quarrying and the selection and production of aggregates is critical to the success of these projects.

Heidelberg Materials UK have a strong track record in this area, supported by a dedicated project delivery team and a robust, internally sourced material supply chain that has been central to the delivery of high-quality materials to Hinkley Point C (HPC) in Somerset for more than 13 years. The company is now using the knowledge and experience gained at this site, through intelligent replication, to supply Sizewell C on the East Suffolk coast, where it is already supplying aggregate, cement, ground granulates blast-furnace slag (ggbs), and concrete as part of the plastic cut off wall supply.

Nuclear concrete

The raw materials used to produce nuclear-grade concrete must be of the highest quality and in precise ratios to achieve the high strength and durability required, as set by the Office for Nuclear Regulation. Achieving this at scale, and doing so consistently, is a huge challenge; one that Heidelberg Materials UK met at HPC by developing a bespoke quality-management system focused on quality, efficiency, and repeatability.

The system provides a digital framework for monitoring and verifying each stage of material production and delivery. It tracks compliance against project specifications and regulatory standards, supports documentation, and allows real-time quality monitoring. It also contributes to compliance by integrating testing data, inspection records, batch histories, and compliance certificates to enable full traceability at every stage of production.

Quality assurance

Every material entering Heidelberg Materials’ nuclear supply chain is subject to extensive testing. Concrete mixes are assessed through regular sampling for 28-day strength requirements, and monthly reports document compressive strength, consistency, and temperature. Quality data are reviewed continuously to detect trends, guide adjustments, and assist the client in conformity. All material is accompanied by documentation confirming origin, test results, and compliance with project specifications. The company’s testing regime is supported by its national laboratories, equipped with calibrated, UKAS- certified equipment.

The standards and learnings established at HPC have created a culture of quality assurance and accountability across the wider business. It is embedded in every site, with employees aiming to uphold the same level of rigour and attention to detail, regardless of project size or scope.

The Heidelberg Materials team based at HPC manages on-site batching, delivery scheduling, pour co-ordination, and quality assurance, operating as a single point of contact for the client, with shared responsibility across all aspects of delivery. The team uses real-time digital dashboards to monitor material properties, site readiness, and compliance, and has built a reliable, resilient logistics network which uses fixed routines and strict oversight to make sure materials arrive safely, on time, and within specification.

Heidelberg Materials’ nuclear team is now sharing best practice and lessons learned from its close involvement in supplying Hinkley Point C in Somerset with the team at Sizewell C in East Suffolk (CGI image above)

Nuclear safety culture

A strong nuclear safety culture is essential to all operations at HPC, including fostering a questioning and challenging mindset among the workforce. Employees are encouraged to raise concerns, challenge assumptions, and seek clarification whenever there is uncertainty. This approach reduces the risk of error and supports continuous improvement. A clear, structured process for reporting and resolving concerns ensures that quality and safety are maintained at all levels.

Heidelberg Materials’ nuclear team is now sharing best practice and lessons learned from its close involvement in supplying HPC with the team at Sizewell C in East Suffolk. Over the past 12 months it has helped develop and trial the concrete mix to construct the initial phase of the cut-off wall, which will run around the perimeter of the site of the new nuclear power station. It is comprised of concrete panels and a plastic wall that will extend more than 50m into the ground, which will create a watertight barrier to enable around four million cubic metres of earth to be excavated from the site and allow construction of the two reactor units.

For this stage of the project the company is supplying around 35,000m3 of concrete containing admixtures from Sika to ensure workability, allow a longer window for placing and compaction, and inhibit the ingress of groundwater. The material is being supplied from its Ipswich concrete plant as well as a mobile batching plant installed at the Sizewell C site.

Supplying nuclear projects requires more than high-quality materials. It demands a controlled, repeatable system for delivering under strict nuclear standards. Heidelberg Materials have met this challenge through a bespoke technical framework operated by a highly qualified team of experts. The result is a supply chain that delivers consistent, nuclear-grade concrete at scale, backed by rigorous documentation, real-time monitoring, and continuous oversight. Although developed to meet HPC’s nuclear requirements, these methods and systems set a benchmark for quality, consistency, and control that can be tailored to any client seeking the highest standards of performance and assurance.