J0 milestone achievement 

Less than a year after Hinkley Point C met one of its biggest project milestones – finishing the foundations for the first main reactor and surrounding buildings – it is celebrating the same milestone again for the second reactor. 

This ‘J0’ milestone marks the start of construction of the reactor buildings above ground. Jalon Zero (J0) is a French term meaning ‘moment in time’. The foundations, known as the common raft, are made up of 20,693m3 of concrete, strengthened with 4,569 tonnes of reinforced steel across five areas.

The fifth and final raft pour to complete J0 on Unit 2 took place over three days at the end of May, when 9,000m3 of concrete was placed in one continuous pour. This is a big achievement, particularly because this milestone was set out at the start of construction, and it was reached on schedule.

Last years’ identical pour on Unit 1 topped the previous record for the largest concrete pour in the UK, which was previously held by the Shard in London. 

Local Leanne’s lessons learned

Leanne Tarr, Logistics Manager for Bylor’s Batching Plant team, never expected her typical week to involve co-ordinating the logistics behind pouring thousands of cubic metres of concrete.

She grew up on Exmoor and began her career working as a shepherdess in lambing sheds, so her current role came as a surprise to her. Plugged in asked Leanne more…

How did you go from birthing lambs to the batching plants?

“Growing up locally, I followed Hinkley Point C from its early development through family members working at Hinkley Point B. After moving back to Minehead from Wales, I began working for Somerset Larder as a server in one of the canteens on site and moved from there into a cleaning role for the contractor Bylor. The team noticed I was methodical and hard-working and offered me an administrative role to cover maternity leave. Three years on, I now handle the team’s logistics management.”

What does your role involve?

“I co-ordinate the team’s concrete pours, processing concrete orders from different areas across the site and sending them on to the batching plant and concrete lab, so they can plan the concrete production and testing.”

How do you feel about achieving J0?

“Without the concrete we’re helping to produce, construction couldn’t happen, so we have direct involvement with this milestone. All the team members feel really proud to work at Hinkley Point C, and this is a great moment for the project.”

How did the latest J0 compare to last year’s?

“All concrete pours need careful planning, but we learned a lot from the experience last year and everyone seemed a little more confident in the run-up this time because they knew what to expect. We still called it the ‘mega-pour’ though!”

How Hinkley Point C is benefiting from lessons learned

Teams have been using the knowledge gained from other nuclear power station builds and their own work on the site’s first reactor to increase efficiency and productivity on the second reactor. 

Here are just a few ways the teams are sharing knowledge and improving processes to make work on the second reactor more efficient:

  • Prefabrication is a major area of innovation at Hinkley Point C. Large components are assembled in a factory environment and lifted into place complete, keeping quality standards high and reducing safety risks. The installation times of the second reactor’s steel reinforcement for the common raft are more than 25% faster than the first unit.
  • The project’s workforce is developing industry-leading skills and expertise as team members gain more and more knowledge during the build. Liza Haile, Section Engineer, Bylor, explained: “On the second reactor, we used a lot of the same workforce from the first and we’re seeing the benefits of that. Working on one of the raft pours for J0, having the knowledge from the people on the ground helped us progress faster and we completed the pour a week ahead of schedule.”
  • Each step in preparing for a J0 concrete pour is critical to the next. When the second reactor works met a problem with the late delivery of equipment, teams were able to use the knowledge they had gained on the first unit to adjust the sequence of works. The changes cut the time from 10 weeks to 10 days between the arrival of the equipment and the concrete pour, and the works were completed on time.