Reactors

Steam Cycle HTGR to Provide Sustainable Energy Source for Process Heat Users

Issue 2 and Volume 5.

By John Mahoney, NGNP Industry Alliance Limited

The NGNP Industry Alliance recently selected the Areva steam cycle high temperature gas-cooled reactor (SC-HTGR) for development as a future industrial heat source. The SC-HTGR will provide high temperature steam for a variety of applications such as chemical processing, refineries, heavy oil recovery, tar sands and oil shale recovery and upgrading, and synthetic fuel production, with the potential for major environmental and economic benefits.

Such industrial applications are inherently energy intensive, accounting for a substantial fraction of North America’s energy economy. Today, this energy is supplied almost entirely from fossil fuels. Conventional nuclear reactors do not reach the temperatures required, and renewables such as hydropower, wind, and photovoltaics are not viable large scale heat sources. This reliance on fossil fuels brings significant challenges due to energy price volatility, potential supply disruptions, and environmental concerns.

The unique capabilities of the modular SC-HTGR make it an ideal alternative to fossil fuels for many industrial applications as well as for electricity generation in the small reactor market. The ceramic core and inert coolant allow the reactor to operate at much higher temperatures than conventional nuclear reactors. The modular nature of the design allows plant configurations to be easily tailored to meet the needs of specific customers. The reactor’s inherent safety characteristics support collocation in close proximity with energy users. The nominally 625 MWt module size maximizes economic performance while maintaining passive safety benefits.

The reactor core structure is graphite which is stable at extremely high temperatures and which cannot melt. Coated fuel particles are at the heart of the reactor design each having multiple ceramic coatings that retain the fission products up to extremely high temperatures, well beyond temperatures reached during normal operation and accident scenarios. The primary coolant is helium which is inert and single phase under all possible conditions. These features allow the SC-HTGR to operate at high temperature (750°C core outlet) and produce steam at 550°C (1050°F).

The modular SC-HTGR steam supply system will be tailored to the needs of specific customers, allowing a good match with the energy needs of each facility. It also provides increased operational flexibility and reliability. Since most industrial facilities are also large electricity users, systems can be configured for cogeneration using excess steam.

Perhaps the most important benefit of the SC-HTGR is the HTGR’s well-known safety features. In the event of a loss of cooling, the SC-HTGR will naturally shut down. In an accident, temperatures are controlled by completely passive means. This requires no electrical power, and it does not require any component to change state or position.

The passive safety characteristics of the SC-HTGR are particularly important for process heat applications, since the HTGR heat source would be collocated near the energy user. The safety features of the SC-HTGR go beyond simply maintaining public safety. They also minimize investment risk by avoiding damage that would prevent restarting the plant following an accident. Potential risks for both the SC-HTGR steam supply system and the collocated process heat user are managed successfully.

The SC-HTGR provides an attractive alternative for industrial heat users facing major challenges today and in the future. Increasing environmental challenges are being raised on the use of fossil fuels including anticipated constraints on CO2 emissions. The SC-HTGR provides an emissions-free alternative to fossil fuels, avoiding these penalties now and in years to come.

Fossil fuel price volatility is another major challenge. Oil and gas price fluctuations in recent decades illustrate the difficulty of forecasting long-term energy prices. The effects of increasing demand and finite supply are completely overshadowed by near-term volatility. Substituting nuclear heat in place of fossil fuels gives users stable competitive energy prices for decades to come.

Security of energy supply is a major concern for individual energy users as well as the U.S. economy. Reliance on imported energy increases our vulnerability to supply disruptions due to external events beyond our control. Displacing fossil fuels with domestically produced nuclear heat will reduce vulnerability to supply disruptions from foreign suppliers.

SC-HTGR technology provides a viable alternative for current energy intensive industries such as chemicals, refining, etc. It will support future industries like coal-to-liquids and synthetic fuel production as advanced processes come into use. And development of the SC-HTGR will pave the way for development of more advanced very high temperature reactors to support needs in other industries including steel making, and high efficiency hydrogen production. The technology will also enable the production of synthetic chemical feedstocks to further reduce demand on limited fossil resources.

By addressing these challenges, the SC-HTGR allows industries to remain in North America rather than moving offshore in pursuit of lower energy prices. It is a game changing technology for industry since it will allow placement of new plants in geographic locations where industrial development had been limited by the lack of natural gas infrastructure and pipelines. This improves the future U.S. outlook and improves the balance of trade while providing an opportunity for thousands of domestic jobs, in engineering, construction trades and the operation of SC-HTGR steam supply systems for end user process industries.

Providing a viable alternative to fossil fuels brings substantial environmental and economic benefits, preserving major segments of the U.S. industrial sector and providing sustainability for key industries that make modern lifestyle possible.

More Power Engineering Issue Articles
Power Engineerng Issue Archives
View Power Generation Articles on PennEnergy.com