Ansaldo Nuclear successfully completes first testing on a key safety system for the Westinghouse Lead Fast Reactor

Ansaldo Nuclear recently carried out the first experimental campaign with a state-of-the-art experimental infrastructure, known as the Passive Heat Removal Facility (PHRF), to support Lead Fast Reactor (LFR) technology development — with promising results.

The PHRF is a testing facility recently erected to study and validate the effectiveness of the Passive Heat Removal System (PHRS) for the Westinghouse Lead-cooled Fast Reactor (LFR) — a Generation IV, competitive, modular and passively safe nuclear power plant.

In the LFR, the PHRS passively removes decay heat in the event that the Normal Decay Heat Removal System fails or is unavailable. This is achieved via water boiling in an annular pool surrounding the LFR’s Guard Vessel, followed by transition to natural convection of air once water is depleted.

To test this key safety system, Ansaldo Nuclear — a leading organisation in LFR technology development — was contracted by Westinghouse as part of Phase 2 of the Advanced Modular Reactors (AMR2) program co-funded by the UK Government’s Department for Business, Energy and Industrial Strategy (BEIS), to design, install and operate the PHRF at Ansaldo Nuclear’s extensive testing facilities in Wolverhampton.?

The PHRF reproduces a portion of the Westinghouse LFR’s PHRS on a relevant scale. Consistent with one of the most unique features of this system, it is the first facility in the world to investigate the operation of a passive heat removal system that requires no activation for its operation, further demonstrating the robust safety that Westinghouse and Ansaldo are pursuing with this reactor concept.

After lifting the 12-tonne, eight-metre tall main body of the facility into position, and connecting the air/steam ducting to achieve an overall height of approximately 23 metres, the Ansaldo Nuclear team began testing, which was divided into two stages.

The first stage, called the ‘Air Phase’, involved bringing the heating plates reproducing the LFR’s vessel up to a temperature of 700°C, in order to analyse the thermal performance of the system in natural circulation. In the subsequent ‘Water Phase’, the facility was filled with water before being heated up to 700°C, this time to assess the heat removal performance of the system during boiling conditions as well as during the water-to-air transition.

According to Marco Caramello, Project Engineer at Ansaldo Nucleare and Ansaldo’s technical lead of the AMR2 program, both experiments were completed successfully and showed promising results:

“As the PHRF is a simulation of the real system, the results of the tests will enable Westinghouse and Ansaldo Nuclear to validate how the safety system will behave in the actual plant, and therefore to confirm its operational viability.

“Testing infrastructures of this type are known to unveil challenges at first start-up, but our flexibility, extensive design efforts, and predictive simulations allowed us to complete the tests without encountering any unforeseen complications. Although it’s still premature to draw any conclusions, as more tests are required to comprehensively substantiate the performance of this safety system, the results are promising and we’re proud of the key milestone achieved with the construction and first operation of this facility.

“Technologies like the Westinghouse LFR could play a key role in achieving decarbonisation goals while being competitive and sustainable, and it’s important that Ansaldo is involved in the development of this next generation of nuclear energy.”

Concetta Cantone, Project Manager at Ansaldo Nuclear’s Wolverhampton facility, spoke about the unique challenges of the PHRF experiments:

“Ultimately, all the data we generate while engineering this system is information that will be used for the full-scale model in the reactor. It’s vital that we verify and qualify our numerical models so that, in the long-run, we can certify that this reactor is safe.

“The main challenge is that the test facility and our experiments are running in parallel with a design that is evolving, and that they are meant to inform. Because of that, we’ve had to be incredibly dynamic in the way we approach the project, adapting features and ensuring that it all fits within the original plan and budget.

“This flexibility has enabled us to make partial modifications throughout, optimising the internal geometries and hydraulics of the system and ensuring that we provide Westinghouse with a facility that is as effective as possible.”

A number of international organisations have collaborated with Ansaldo Nuclear on the various phases leading to the operation of the PHRF. In addition to Westinghouse and ENEA, Frazer-Nash Consultancy carried out dedicated numerical analyses, Argonne National Laboratory shared lessons learned on the operation of a similar facility in the United States, and several other UK organisations were involved in the construction of the facility including Lyndhurst Precision Engineering, Parkers, the WEC Group, Intertherm Integrated Services, etc.

As part of the contract, and consistent with the Cooperation Agreement for LFR Development signed with Westinghouse in 2022, Ansaldo Nuclear has also designed, is currently installing and will soon be operating the versatile lead loop facility (VLF), which it will use to test prototypical high-priority components of the Westinghouse LFR.

Read more about the Westinghouse LFR.