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The Hualong One (also known as Hualong 1 and HPR1000) is a pressurized water nuclear reactor with features merged from reactors made by the China General Nuclear Power Group (CGNPG) and the China National Nuclear Corporation, and originally derived from a French design (which was itself derived from a US Westinghouse design).

Hualong One merged design Wikipedia

China’s “Hualong 1” passes the first stage of the UK GDA process by Euan Mearns & Andy Dawson; Energy Matters; 24 Nov 2017

With little fanfare last week, the Chinese designed HPR1000 (previously Hualong-1[1]), pressurised water reactor, cleared the first of four stages in the General Design Assessment (GDA) administered by the UK Office of Nuclear Regulation (ONR). China General Nuclear (CGN) proposes to build 2 reactors of this design at the Bradwell site in England, in partnership with French state-owned EDF that currently operates all UK commercial reactors.

This guest post by Andy Dawson gives a preliminary overview of the design focussing on safety systems.

UK HPR1000, Generic Design Assessment (GDA) website [1]

CGN and EDF, through their joint venture company General Nuclear System Limited, commenced the Generic Design Assessment (GDA) process for the UK HPR1000 in January 2017.

General Nuclear System has been established to act on behalf of the three joint requesting parties (CGN, EDF and General Nuclear International) to implement the Generic Design Assessment of the UK HPR1000 reactor; more information on the each of these companies and the structure of General Nuclear System can be found on the about us page. For practical purposes, General Nuclear System is referred to as the ‘UK HPR1000 GDA Requesting Party’.

This website has been set up to publish information on the HPR1000 nuclear reactor design that is currently undergoing assessment by the UK nuclear regulators – the Office for Nuclear Regulation and the Environment Agency. You can find out more information about the process on our GDA process page.

On 15 November 2018, the regulators concluded that the information submitted by General Nuclear System during Step 2 was sufficient to allow the start of Step 3. As part of the GDA process we continue to invite you to comment on the HPR1000 reactor design and the regulatory submissions that we make to the regulators.

Comments received by 25 October 2019 have been considered as part of the ONR’s assessment of Step 3. The Environment Agency will continue to accept comments for this step after this date and will be consulting on its findings so far, in due course. More information is available on the EA website.

Within this site you will find information on the HPR1000 reactor technology, design, safety and environmental features. You can also access the range of technical documents that will be submitted to the regulators throughout the process in our document library.

"UK HPR1000 moves to final design assessment stage", World Nuclear News [2], 13 Feb 2020

The UK HPR1000 is the Hualong One design that General Nuclear Services - a subsidiary of EDF and China General Nuclear - proposes to use at a prospective new nuclear power plant in Bradwell, England.

"The objective for GDA is to provide confidence that the proposed design is capable of being constructed, operated and decommissioned in accordance with the standards of safety, security and environmental protection required in Great Britain," Ana Gomez-Cobo, ONR’s head of UK HPR1000 regulation, said.

"Our assessment to date has not identified any fundamental safety or security shortfalls that would prevent us issuing a Design Acceptance Confirmation (DAC) for the UK HPR1000 design. However, we have identified a number of areas for which further substantiation is needed from the Requesting Party; these have been captured as Regulatory Observations. Although progress so far is encouraging, a lot of work by the Requesting Party is still required. We will continue to rigorously assess safety and security submissions throughout Step 4 of GDA."

The GDA is a voluntary process for reactor vendors - it is policy rather than law - but it is a government expectation for all new-build projects in the UK. In January 2017, the British government formally requested regulators start the process for the UK HPR1000. The regulators, who have said they aim to complete the GDA of the UK HPR1000 in late 2021, have published a report summarising their Step 3 assessment here.


The starting point for this commentary is that this is a VERY conventional Light Water Reactor design, with a design ancestry going back to a highly successful 1970s Westinghouse Pressurised Water Reactor with evolutionary change thereafter. The direct precursor is the 900MW Framatome design (based on licensed Westinghouse technology) built at Daya Bay in the 1980s. There have then been several further design evolutions driven by the Chinese themselves, resulting in Hualong-1, several of which are in build in China and in Pakistan. The baseline plant for the UK GDA entry is Fanggchengang 3, currently about 2 years into build (inset image), and due on line in 2022. From a western perspective, this may appear unpronounceable. I can’t comment on why they didn’t select the other potential reference plant, which is running slightly earlier – at Fuqing.

It’s not a radical leap in the way that the AP1000 attempted simplification of the PWR concept, or that the EPR tried to address potential regulatory issues by delivering massive redundancy on key systems.

Gross electrical output is 1180MW – although not stated, net output is likely to be in the 1130-1160MW range, after losses to powering internal systems. Thermal output is 3150MW, giving an overall efficiency of 37% – respectable for a PWR, and entirely comparable with AP1000 and EPR, and somewhat better than ABWR. The standard refuelling cycle is 12-18 months.

The core is again, directly reflective of Westinghouse design practice; it consists of 177 fuel assemblies, each consisting of a 17×17 matrix of fuel pins. Cladding is conventional zircalloy (of which more later).These have been lengthened from the precursor designs to reduce linear power density, and improve neutron economy. The core design makes extensive use of “burnable poisons” to manage the neutron flux distribution, to this same end.

However, unlike most recent designs, it doesn’t appear that the core is surrounded by a cylindrical steel neutron reflector. This means that the fuel usage (aka “burn-up” is somewhat less efficient that in designs like the EPR. EPR is claimed to be capable of running to a burn-up of 60GWd/t (gigawatt-days per ton) against HPR1000s 47GWd/t. This may also have some relationship to another striking feature; the entire main Reactor Pressure Vessel (RPV) is produced as a single forging, as opposed to the mixed forging/welding of other designs. This should serve to significantly improve the fracture mechanics of the RPV, and since neutron embrittlement tends to be more of an issue at welds than in forged metal, is probably integral to justifying the claimed design life of 60 years.

It’s a “three-loop” design, another design characteristic directly inherited from its Westinghouse (and later Framatome) precursors. That means it has three Steam Generators (SG), each with a single circulating pump. In this area, the other designs with, or in process for UK GDA differ. ABWR has, of course, no steam generators at all (steam raising takes place directly in the RPV). AP1000 has just two large SGs, with a single hot line from the reactor and a pair of cold return legs for each SG with a circulating pump for each cold leg mounted integrally with the SG. EP1000 has four SGs, with a dedicated pump for each.

Externally, it seems to be a compact unit, in appearance very similar to the stations familiar to anyone who’s spent time in France. It has a typical modern “dual containment” design, with an outer reinforced concrete “shield wall” providing protection against missile or aircraft impact, and an inner pre-stressed concrete pressure bearing “true” containment.

more ...

HPR1000, reactor coolant system.png
The time-lapse video above shows construction of the first of two Hualong One reactors at China's Fuqing nuclear power plant, alongside four CPR-1000 reactors, from which the HP1000 design is derived. Primary coolant system showing reactor pressure vessel (red), steam generators (purple), pressuriser (blue), and pumps (green) in the three coolant loop Hualong One design]]

The video starts with construction of the domed containment vessel followed by:

  • 0'40" positioning one of the three steam generators (shown purple in the diagram above right),
  • 0'46" the reactor pressure vessel (red),
  • 0'54" the pressuriser (blue).
  • 1'11" fitting the top cover of the steam turbine. This is in the turbine hall, outside the containment vessel in which all the previous components shown are located.
  • 1'15" loading of fuel bundles into the reactor.
  • 1'19" synchronising the power station and connecting it to the grid.

Proposed UK build

There is a proposal to build a twin HPR1000 power station at Bradwell in Essex, alongside the now decommissioned Bradwell A Magnox power station.

The new station would be built by a consortium of CGN and EDF, as a joint venture company called General Nuclear System Limited.[2]

Information about the project, including its progress through the UK's Generic Design Assessment process, is on the company's website.

Footnotes and references

  1. The design is still also known as Hualang 1
  2. General Nuclear System: About Us