Building Barakah28 September 2012
Safety-related concrete began pouring on July 18 at the site of the UAE’s first civil nuclear reactor in the western part of the Abu Dhabi emirate, after the Federal Agency for Nuclear Regulation approved its construction permit the previous day. The reactor’s name, whose official English translation was slightly changed in June from ‘Braka’, is scheduled to be completed in 2017.
Preliminary civil construction work on the site began in 2010.
According to Emirates Nuclear Energy Corporation, the government-owned nuclear developer, this work included excavation for units 1 & 2, dredging for the intake and outfall channels, construction of the marine breakwaters, wharf construction, excavation and construction of the cooling water ducts and foundations for the safety related concrete were prepared. This included the installation of cathodic protection, layers of lean leveling concrete with waterproofing, structural rebar, embedments, piping, conduit, grounding cable and sump liners.
Nuclear concrete will be poured for unit 2 in 2013.
The construction licence allows ENEC to import nuclear components, but not nuclear material. The construction licence requires ENEC to report significant events in construction within 72 hours. FANR will continue inspections during construction. As construction proceeds, ENEC will be required to submit an application for a licence to operate the reactor (which it plans to file in 2015), and also a final safety analysis report. The Environment Agency will require an operation environmental permit, which will need an operation environmental management plan. Many of the most technical issues in the reactor design—such as the instrumentation and control system—will be reviewed as part of the detailed design to be submitted during construction. As construction proceeds, site security will also ramp up, increasing with the arrival of the first component important for safety, again with the delivery of nuclear fuel, and again with operation.
The Barakah site is 250 km (165 miles) from Abu Dhabi, and about 75 km from the country’s border with Saudi Arabia, which surrounds the Emirate to west and south. The flat desert environment of the site region, not tectonically active for 100 million years, is also sparsely populated; the nearest town is Sila’a-Ba’aya, 48 km west-northwest, with 7000 residents in 2005.
The design reviewed is the 4000 MWt, 1390 MWe Korean APR-1400 PWR, whose reference plant is South Korea’s Shin Kori 3&4 plant currently under construction. That design is itself based on the US Combustion Engineering System 80+ design exported to the country in the mid-1980s.
The reactor design has been modified for local regulations and site-specific characteristics. For example, UAE requirements call for resistance to impact from a large commercial aircraft strike, so containment building walls and auxiliary building walls are thicker than called for in the original design.
The Arabian Gulf has generally higher temperature than the Yellow Sea and Sea of Japan off of South Korea. As a result, the condenser is enlarged, circulating water system intake and discharge conduits are enlarged, the emergency diesel backup generators’ electricity capacity is increased from 8000 to 8700 kW, and the electrical capacity of alternate AC diesel generators increased from 7200 to 8700 kW. A seawater bypass system not in the original design mixes seawater with cooling water to reduce the effects of discharging warm water to the Arabian Gulf (regulatory limit of discharge temperature above ambient temperature is 5°C). The reactor pulls in seawater in a once-through cycle to cool the secondary loop in the condenser with a maximum flow rate of 172.5 m3/second/unit.
Because the site is prone to sandstorms and flying dust, air handling units equipped with sand trap louvres, sand separation units and filters have been added to many site heating, ventilation and air conditioning structures. Corrosive soil conditions change the material of buried fire protection water distribution system piping from iron to HDPE. Because the UAE’s electrical grid operates on a frequency of 50Hz rather than 60Hz, the main turbine rotation is slowed from 1800 to 1500 RPM, and the reactor coolant pump parameters are also changed.
Changes to the plant design to respond to lessons learned from the Fukushima accident last year include proposals to install passive autocatalytic recombiners in the spent fuel pool building, extending the life of batteries from 8 to 16 hours, and extending on-site fuel supplies from 8 to 24 hours’ worth. Also, to combat station blackout, plans call for the two emergency diesel generators and auxiliary AC diesel generator to be linked via a cross-tie design.
Regardless of design, the turnkey contract calls for the reactor to not only be built by KEPCO and its subcontractors, but also operated by it. Both of those key roles will be dominated by contractor Korea Hydro & Nuclear Power (KHNP), the engineering, procurement and construction contractor, and power station operator. Other important subcontractors are KEPCO Engineering & Construction, which is responsible for nuclear power plant design and engineering, Hyundai/Samsung Joint Venture for construction, Korea Plant Service and Engineering for maintenance, Korea Nuclear Fuel, which will provide reloads for the 241-assembly core based on fuel used in Korea since 2006 (maximum burn-up 60,000 MWD/tHM). ENEC announced a 15-year fuel services procurement deal with AREVA and TENEX for uranium concentrates, conversion and enrichment, and with Rio Tinto and Uranium One for natural uranium, Converdyn for conversion and Urenco for enrichment. Other significant vendors mentioned in the executive summary of the UAE nuclear regulator’s report are Westinghouse and Toshiba, which are supplying control rods, and Doosan Heavy Industries, which is supplying turbine and generators.
The speed of the design review, 18 months, is as quick as other aspects of the UAE project: government nuclear developer ENEC submitted the construction application 12 months after the surprise winning contractor from a formal tender process, Korea Electric Power Company, was announced in late December 2009. The country only developed a nuclear policy in 2008, and elements of the nuclear infrastructure, such as ENEC, FANR, were only set up in the last few years.
The regulator’s green light means that a number of key documents have been reviewed and generally approved: ENEC’s Construction Licence Application and the Preliminary Safety Analysis report (PSAR) that supports it, a site security plan, a nonproliferation plan, post-Fukushima lessons learned plan, aircraft impact assessment report, a severe accident report, and an environmental impact assessment. The EIA includes a non-nuclear component, which was approved by the Environment Agency—Abu Dhabi, and a nuclear component, which was also approved by the EA with help from FANR and an unnamed technical consultant.
FANR said that its review drew on three consortia of technical support agencies. The Baynuna Nuclear Energy Services-Information Systems Laboratories consortium consists of the Abu Dhabi-based company and the USNRC technical support organisation (TSO), and Chesapeake Nuclear Services company. The NT consortium includes Numark Associates, another NRC TSO, AMEC Nuclear Safety Solutions (of Canada), TUEV NORD Nuclear, a TSO to several German federal states, and Finnish research organisation VTT (a TSO to the Finnish nuclear regulator). The Riskaudit consortium consists of the EC non-profit, IRSN (a TSO to the French nuclear regulator) and Germany’s GRS.
FANR’s review of the 9000-page PSAR, which involved 200 people, was documented in a 2500-page Safety Evaluation Report, of which only the executive summary has been made public. FANR reports that during the review process there were 1600 requests for additional information from ENEC, and 1100 requests for information from the Korean regulator. The preliminary safety analysis report of the APR-1400 design was approved by the Korean Institute of Nuclear Safety in 2008.
Since the basic reactor design had already been reviewed by another nuclear regulator, FANR said that it used the KINS Safety Evaluation Report to gloss over some parts of the PSAR, provided that the documentation was complete, that the Korean requirements meet the FANR requirements, that the Korean technical basis was clear and acceptable, and that there were no changes from the reference plant that were likely to have a significant impact on nuclear safety. The other parts of the PSAR that did not meet these were reviewed independently and in depth. The report did not state the proportion of each type carried out in the review.
There are two other important issues that are unlikely to be resolved until well into the construction phase. First, ENEC has proposed changing the type of containment concrete from the reference design. Second, the report complained that there were problems in the severe accident section of the PSAR about computer code validation, incomplete technical justifications, inconsistent data, and missing information. FANR reports that ENEC is working on this to an agreed schedule, although it did not say what that schedule was. Second, although it appears that the plant is in a zone of low seismic risk, the review found that seismic response parameters of equipment and equipment supports were not sufficient in the reference plant. As a result, the regulator has promised to review safety-important air-operated valves and snubbers during construction.
According to IAEA data, the UAE is the first new country to authorise nuclear power plant construction since China did so in 1981.
This article was published in the September 2012 issue of NEI magazine.