More than 50 years ago, in 1968, faced with a serious over-reliance on heavy fuel oil for power generation, ESB decided to develop an option to build a nuclear power station in Ireland, writes Fellow of Engineers Ireland Frank Geary. It set up a group of young engineers to equip it with the necessary skills and preparations to allow a future decision on the project. Over the following decade the Nuclear Project Group made major progress in achieving that goal. (Part II can be read here.)

The 1970s, however, were a period of great change for Irish electricity supply and for nuclear reactor technology and, in 1978, with significant inputs from the group, ESB decided, on economic and technical grounds, not to proceed with the nuclear project. 

Sean Coakley, head of design and development in ESB’s Project Department, announcing plans to build a nuclear power plant at Carnsore Point, Co Wexford. Click on this link to watch the video


The second half of the 1960s was a period of rapid change for Ireland and ESB. After many years of relative stagnation, the country was developing rapidly. Demand for electricity was growing at about 10% per annum, doubling in less than seven years.

All significant peat and hydroelectric resources were already serving power stations. Extra capacity needs were met by imported heavy fuel oil. Between 1965 and about 1970 ESB went from commissioning 60MW units to designing and building units of 250/270MW, all oil fired. More than 70% of ESB’s generation was based on oil.

In 1968, faced with this overdependency situation, JJ Kelly, ESB’s chief engineer and later chief executive, decided that ESB should equip itself with the possibility to diversify its fuel sources, and with the option of building a nuclear power station. Kelly decided to set up an engineering team to investigate the available nuclear technologies and to do the necessary preparatory work to position ESB to move rapidly to build such a station, should such a decision be made.

Establishment of the Nuclear Project Group

In mid-1968, following a wide selection process, four engineers were selected as the first members of the team. Further groups of four were appointed in each of the following years, including a nuclear physicist and a power station chemist, making a total team of 12, all of whom received international training for more than a year.

They reported to Sean Coakley, head of design and development in ESB’s Project Department, who was to lead the project and who already had the assistance of a senior engineer with extensive experience in UK nuclear stations. A number of others joined the team later.

As it was expected that the go-ahead for an Irish nuclear station was not sure in the short term, all those chosen for training were aged about 30.

In several countries of comparable size to Ireland, their initial nuclear investigations were often university led and academically centred but, right from the beginning, the ESB team was named the Nuclear Project Group and its focus was firmly on doing what was necessary to deliver a safe and commercial nuclear power plant to the Irish electricity system.

The initial group of four engineers received their training in the UK, through a combination of academic courses and attachments to the UK Atomic Energy Authority and the power stations of the Central Electricity Generating Board (CEGB). They quickly identified, however, that the nuclear technologies adopted by the UK were unsuitable for Ireland, so, on their recommendation, the later groups were trained in the USA and Germany, where the internationally dominant Light Water Reactor (LWR) technology was used. 

Light Water Reactor 

Getting started

After their training period, the team started to tackle the huge task of giving ESB a credible basis for considering whether a nuclear power station should be included in its future generation plant programme.

ESB’s approach to the design and construction of its large power plants was to break them into multiple contracts covering the civil, electrical and mechanical engineering aspects of the project.

This was considered to allow the optimum selection of major plant systems and it had the added attraction of allowing the maximum participation of Irish companies, many of which were of relatively small scale.

ESB’s engineering departments had accumulated an impressive expertise in organising the complex tasks of design co-ordination and construction management needed to build large power plants.

Although the turbo-generator and auxiliary plant aspects of a nuclear plant were essentially unchanged, it was clear that using a nuclear reactor as the source of steam was a huge change with wide-ranging consequences.

The group decided to concentrate their work on the reactor, its structures, auxiliaries and support systems, the so-called nuclear island, as well as on the external factors involved in a decision to build a nuclear station in Ireland.

To maximise use of the expertise and experience of the major reactor manufacturers and to ensure undivided responsibility for the nuclear plant, a turnkey plant contract was clearly necessary for the nuclear island. This was no place for the traditional multi-contract approach.

Major areas of concern included the nuclear reactor itself and its controls, the mechanical plant systems involved (especially the high pressure reactor vessel, the steam generators and the related pumping and piping systems) and, of course, the nuclear safety aspects of the project, including the systems to ensure the safety of the plant in the event of any emergency.

Through detailed study of the available reactor designs and extensive discussions with manufacturers and visits to operating nuclear plants, the team built a knowledge base and a credibility with the makers and others in the industry.

A comprehensive specification for the nuclear island was prepared which would allow for competitive bids from the major firms making reactors which could be suitable for use in Ireland. (As part of the licensing/permitting process this specification was later submitted to the Nuclear Energy Board (NEB) and to the European Commission, Ireland having joined the EEC in 1973.) 

Safety issues

The safety aspects of the project were considered seriously from the beginning of the project. The decision to concentrate on LWR technology meant that the plant would be based on designs currently operating or under construction in large countries with established safety licensing systems.

The group examined these designs in detail and sought to incorporate the best ideas from the various sources in their design specification. It was understood from the outset that the detailed specification and the finalised design would be subject to stringent requirements from both Irish and European licensing authorities.

In addition to the normal systems for the control and shutdown of the reactor, all nuclear stations have extensive emergency control systems designed to ensure reactor safety even in the event of a major malfunction.

These systems are fully duplicated and are located at opposite sides of the plant to protect against any single occurrence affecting both. The whole reactor and associated steam generators etc are enclosed in the reactor containment, the large dome characteristic of LWRs. This is designed not only to contain the consequences of any reactor accident but to withstand major external forces, even the impact of a jumbo jet. 

Barakah: UAE starts up Arab world's first nuclear plant – BBC News

Reactor size

The size of the nuclear unit was always an issue for ESB’s proposed nuclear plant.

As a rule of thumb, no one unit should normally be more than 10% of the peak load on an electricity system. Failure of a larger unit would run the risk of a cascade of plant trips with the possibility of widespread blackouts and system shutdown.

For most power companies, strongly connected to neighbouring grids, this is not a major issue, but for Ireland, with no external links in 1970 and only one interconnector between the ESB and Northern Ireland grids, it was a real concern. The peak load on the ESB system was then about 3,000 megawatts (MW), while the peak in the north was about half that.

The smallest commercially available light water reactors at that time were about 400MW. There were several plants of that size in commercial operation in a range of countries but, to a significant extent, these were considered as demonstration plants by the reactor makers who were even then concentrating their development efforts on the much larger and more commercial sizes suited for the large, interconnected grids of their home and primary market countries. There was limited manufacturers’ interest and few prospective orders for the smallest scale commercial reactors.

For Ireland, even this size was problematical. A 400MW unit was just about acceptable on an all-island grid. Northern Ireland Electricity agreed that planning could go ahead on that basis. Also, the rate of growth in electricity demand remained strong, so the ability of the grid to accommodate such a large unit was improving yearly.

Developments later in the 1970s would have a major impact on these assumptions.

Siting of stations

The site requirements for a large nuclear station are largely similar to those for any big thermal generating facility. Apart from the obvious need for suitable foundation conditions, major factors include the need for very large quantities of cooling water (favouring a coastal site) and linking the site to the national grid to export the large amounts of electricity generated. Prudence also indicated the desirability of avoiding the immediate surroundings of large population centres. 

Carnsore Point, Co Wexford, was one site chosen for preliminary drilling; a ind farm is now located there

Preliminary surveys of the coast led to the selection of five locations for preliminary drilling. From these a site at Carnsore Point in southeast Wexford emerged as the best option and ESB purchased the site area and started the steps needed to get site approval. Detailed site investigations were carried out and a full site report was prepared (and later submitted to the NEB and the European Commission).

Government and external regulation

The ESB board was in regular contact with the government and advised it that nuclear power was one of the options being considered to diversify Ireland’s fuel sources.

In March 1973, ESB made a formal application for government approval of the project and this was granted in November of that year. Close dialogue with government continued in the following years as the fortunes of the project rose and fell and as its proposed operating date was repeatedly postponed in response to outside developments.

Recognising the imperative for independent scrutiny of the proposed project, the government passed legislation to establish the Nuclear Energy Board, tasked with overseeing all nuclear activities in the state, including the licensing of ESB’s proposed project, and ensuring that public safety was protected and that the necessary support activities were organised.

The first chairman of the board was Professor Charles Dillon of UCC, an eminent engineer with wide international experience in the power sector. The first chief executive was Chris Cunningham, who came with years of senior background in the UK nuclear industry. (The board subsequently became the Radiological Protection Institute of Ireland.)

ESB mounted a significant public information campaign on nuclear power technology and power plants. Technical papers and articles were written and a wide-ranging series of public presentations and discussions were held, principally in the Wexford area where the proposed project would be located. Groups of national journalists and Wexford county councillors visited nuclear stations in Germany.

Project costs

A major characteristic of nuclear power plants is their different cost structure compared with conventional thermal power stations. For coal, oil or gas plants the costs of fuel over the plant’s working lifetime far exceed the capital cost of the power station. Nuclear stations, on the other hand, are very expensive and slow to build but their fuel costs are a much smaller fraction of the total cost of the power generated.

The design and building of nuclear plants is a major task. Reactor technology is complex and the very high attention that must be paid to certifying the integrity of each individual component and structure to ensure its safety and reliability is both expensive and time consuming. 

Hinkley Point C in Somerset, UK, will be operational in June 2026. Image: EDF Energy

The lead time from the decision to build a nuclear station to its entry into operation is at least 10 years, much longer than that for a conventional power station. This has serious implications for the financing of nuclear plants.

As with all large bespoke engineering projects, it was very difficult to establish a likely capital cost. Discussions with reactor makers and with other power utilities gave some inputs.

Close scrutiny of the technical press and, in particular, the cost breakdowns which US utilities were required to submit to the US Nuclear Regulatory Commission, provide useful information which allowed the Nuclear Project Group to establish a considered estimate for the cost of the scheme.

Fuel for reactor

Although not the largest part of the total cost of nuclear electricity, the fuel for the reactor is clearly an essential element and is also very complex. While coal, gas and (to a lesser extent) oil are all essentially raw materials when burnt, the uranium fuel used in power reactors is a highly engineered product with a complicated story.

Uranium, the fuel used in power reactors, is fairly common in the earth’s crust and its ore is mined in many countries. However, almost all of naturally occurring uranium is stable uranium 238 and only 0.7% is the isotope U235 which is radioactive and thus useful for power generation.

For most types of commercial reactors this concentration is too low to sustain a chain reaction, so the fraction of U235 must be increased (or enriched) to greater than 3%. The enriched uranium, in the form of uranium oxide, is formed into pellets, enclosed in long alloy tubes and assembled in the precise array needed to make up the reactor core.

The two isotopes of uranium are chemically identical, so the enrichment process is very difficult. In the 1970s the only commercial source of enrichment services was the US Atomic Energy Commission (USAEC), which used the huge plants originally designed to supply highly enriched uranium for military purposes.

As demand for power enrichment services increased sharply in the 1970s, the USAEC applied ever more stringent contract conditions, culminating in a requirement for a 10-year non-refundable contract, clearly a huge problem for a tentative project like ours.

Around this time, a British/German/Dutch consortium developed a new enrichment process using gas centrifuges, which were in the experimental stage.

Their joint company Urenco was very keen to land an export order and, even recognising the uncertain nature of the Irish project, it agreed to sign a contract with ESB to provide enrichment services.

While the contract gave ESB certainty on the future supply of enrichment, it also had a very attractive cancellation clause, which was rapidly invoked when the project was dropped. (Gas centrifuge is now the dominant process for uranium enrichment.)

The progress of the project will be covered in Part 2 of this article and published on March 29, 2022. (Part II can be read here.)

Author: Frank Geary, BE, CEng, FIEI