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DOE OSTI2011

Analysis of combined hydrogen, heat, and power as a bridge to a hydrogen transition.

Combined hydrogen, heat, and power (CHHP) technology is envisioned as a means to providing heat and electricity, generated on-site, to large end users, such as hospitals, hotels, and distribution centers, while simultaneously producing hydrogen as a by-product. The hydrogen can be stored for later conversion to electricity, used on-site (e.g., in forklifts), or dispensed to hydrogen-powered vehicles. Argonne has developed a complex-adaptive-system model, H2CAS, to simulate how vehicles and infrastructure can evolve in a transition to hydrogen. This study applies the H2CAS model to examine how CHHP technology can be used to aid the transition to hydrogen. It does not attempt to predict the future or provide one forecast of system development. Rather, the purpose of the model is to understand how the system works. The model uses a 50- by 100-mile rectangular grid of 1-square-mile cells centered on the Los Angeles metropolitan area. The major expressways are incorporated into the model, and local streets are considered to be ubiquitous, except where there are natural barriers. The model has two types of agents. Driver agents are characterized by a number of parameters: home and job locations, income, various types of 'personalities' reflective of marketing distinctions (e.g., innovators, early adopters), willingness to spend extra money on 'green' vehicles, etc. At the beginning of the simulations, almost all driver agents own conventional vehicles. They drive around the metropolitan area, commuting to and from work and traveling to various other destinations. As they do so, they observe the presence or absence of facilities selling hydrogen. If they find such facilities conveniently located along their routes, they are motivated to purchase a hydrogen-powered vehicle when it becomes time to replace their present vehicle. Conversely, if they find that they would be inconvenienced by having to purchase hydrogen earlier than necessary or if they become worried that they would run out of fuel before encountering a facility, their motivation to purchase a hydrogen-powered vehicle decreases. At vehicle purchase time, they weigh this experience, as well as other factors such as social influence by their peers, fuel cost, and capital cost of a hydrogen vehicle. Investor agents build full-service hydrogen fueling stations (HFSs) at different locations along the highway network. They base their decision to build or not build a station on their (imperfect) estimates of the sales the station would immediately generate (based on hydrogen-powered vehicle traffic past the location and other factors), as well as the growth in hydrogen sales they could expect throughout their investment horizon. The interaction between driver and investor agents provides the basis for growth in both the number of hydrogen vehicles and number of hydrogen stations. For the present report, we have added to this mix smaller, 'bare-bones' hydrogen dispensing facilities (HDFs) of the type that owners of CHHP facilities could provide to the public. The locations of these stations were chosen to match existing facilities that might reasonably incorporate CHHP plants in the future. Unlike the larger commercial stations, these facilities are built according to exogenously supplied timetables, and no attempt has been made to model the financial basis for the facilities. Rather, our objective is to understand how the presence of these additional stations might facilitate the petroleum-to-hydrogen transition. We discuss a base case in which the HDFs are not present, and then investigate the effects of introducing HDFs in various numbers; according to different timetables; with various production capacities; and with hydrogen selling at prices above, equal to, and below the commercial stations selling price. We conclude that HDFs can indeed be helpful in accelerating a petroleum-to-hydrogen transition. Placed in areas where investors might not be willing to install large for-profit HFSs, HDFs can serve as a bridge until demand for hydrogen increases to the point where larger stations are viable. For drivers to use them, however, HDFs must sell hydrogen at a price competitive with that of the larger HFSs. Because the marginal cost of producing hydrogen is expected to be higher for small capacities, HDFs may be uncompetitive without (possibly substantial) subsidies or other means to allow them to sell hydrogen at a price below the actual cost to produce and distribute it. Fortunately, HDFs do not need to be subsidized for very long. In our model, installing HDFs only as the demand for hydrogen increased was effective; then closing down all HDFs after five years into the transition made virtually no difference to the resultant accelerated outcome. Even installing much smaller numbers of HDFs only in the second and third years of the simulation and then closing them at the end of the fifth year was helpful.

08 HYDROGEN↗

DOE OSTI2011

Guidebook to Geothermal Finance

This guidebook is intended to facilitate further investment in conventional geothermal projects in the United States. It includes a brief primer on geothermal technology and the most relevant policies related to geothermal project development. The trends in geothermal project finance are the focus of this tool, relying heavily on interviews with leaders in the field of geothermal project finance.Using the information provided, developers and investors may innovate in new ways, developing partnerships that match investors' risk tolerance with the capital requirements of geothermal projects in this dynamic and evolving marketplace.

15 GEOTHERMAL ENERGY↗

DOE OSTI2011

NITRATE DESTRUCTION LITERATURE SURVEY AND EVALUATION CRITERIA

This report satisfies the initial phase of Task WP-2.3.4 Alternative Sodium Recovery Technology, Subtask 1; Develop Near-Tank Nitrate/Nitrite Destruction Technology. Some of the more common anions in carbon steel waste tanks at SRS and Hanford Site are nitrate which is corrosive, and nitrite and hydroxide which are corrosion inhibitors. At present it is necessary to periodically add large quantities of 50 wt% caustic to waste tanks. There are three primary reasons for this addition. First, when the contents of salt tanks are dissolved, sodium hydroxide preferentially dissolves and is removed. During the dissolution process the concentration of free hydroxide in the tank liquid can decrease from 9 M to less than 0.2 M. As a result, roughly half way through the dissolution process large quantities of sodium hydroxide must be added to the tank to comply with requirements for corrosion control. Second, hydroxide is continuously consumed by reaction with carbon dioxide which occurs naturally in purge air used to prevent buildup of hydrogen gas inside the tanks. The hydrogen is generated by radiolysis of water. Third, increasing the concentration of hydroxide increases solubility of some aluminum compounds, which is desirable in processing waste. A process that converts nitrate and nitrite to hydroxide would reduce certain costs. (1) Less caustic would be purchased. (2) Some of the aluminum solid compounds in the waste tanks would become more soluble so less mass of solids would be sent to High Level Vitrification and therefore it would be not be necessary to make as much expensive high level vitrified product. (3) Less mass of sodium would be fed to Saltstone at SRS or Low Level Vitrification at Hanford Site so it would not be necessary to make as much low level product. (4) At SRS less nitrite and nitrate would be sent to Defense Waste Processing Facility (DWPF) so less formic acid would be consumed there and less hydrogen gas would be generated. This task involves literature survey of technologies to perform the nitrate to hydroxide conversion, selection of the most promising technologies, preparation of a flowsheet and design of a system. The most promising technologies are electrochemical reduction of nitrates and chemical reduction with hydrogen or ammonia. The primary reviewed technologies are listed and they aredescribed in more detail later in the report: (1) Electrochemical destruction; (2) Chemical reduction with agents such as ammonia, hydrazine or hydrogen; (3) Hydrothermal reduction process; and (4) Calcination. Only three of the technologies on the list have been demonstrated to generate usable amounts of caustic; electrochemical reduction and chemical reduction with ammonia, hydrazine or hydrogen and hydrothermal reduction. Chemical reduction with an organic reactant such as formic acid generates carbon dioxide which reacts with caustic and is thus counterproductive. Treatment of nitrate with aluminum or other active metals generates a solid product. High temperature calcination has the potential to generate sodium oxide which may be hydrated to sodium hydroxide, but this is unproven. The following criteria were developed to evaluate the most suitable option. The numbers in brackets after the criteria are relative weighting factors to account for importance: (1) Personnel exposure to radiation for installation, routine operation and maintenance; (2) Non-radioactive safety issues; (3) Whether the technology generates caustic and how many moles of caustic are generated per mole of nitrate plus nitrite decomposed; (4) Whether the technology can handle nitrate and nitrite at the concentrations encountered in waste; (5) Maturity of technology; (6) Estimated annual cost of operation (labor, depreciation, materials, utilities); (7) Capital cost; (8) Selectivity to nitrogen as decomposition product (other products are flammable and/or toxic); (9) Impact of introduced species; (10) Selectivity for destruction of nitrate vs. nitrite; and (11) Cost of deactivation and demolition. Each technology was given a score from one to five, five being most desirable, in each criterion. The results for the evaluation, in order from most to least promising was, Electrochemical, Chemical Reduction, Hydrothermal and Calcining. Another report [Steimke and Steeper, 2011] contains a flowsheet and design of an in-tank Electrochemical unit.

08 HYDROGEN↗

DOE OSTI2011

Advanced CdTe Photovoltaic Technology: September 2007 - March 2009

During the last eighteen months, Abound Solar (formerly AVA Solar) has enjoyed significant success under the SAI program. During this time, a fully automated manufacturing line has been developed, fabricated and commissioned in Longmont, Colorado. The facility is fully integrated, converting glass and semiconductor materials into complete modules beneath its roof. At capacity, a glass panel willenter the factory every 10 seconds and emerge as a completed module two hours later. This facility is currently undergoing trials in preparation for large volume production of 120 x 60 cm thin film CdTe modules. Preceding the development of the large volume manufacturing capability, Abound Solar demonstrated long duration processing with excellent materials utilization for the manufacture ofhigh efficiency 42 cm square modules. Abound Solar prototype modules have been measured with over 9% aperture area efficiency by NREL. Abound Solar demonstrated the ability to produce modules at industry leading low costs to NREL representatives. Costing models show manufacturing costs below $1/Watt and capital equipment costs below $1.50 per watt of annual manufacturing capacity. Under this SAIprogram, Abound Solar supported a significant research and development program at Colorado State University. The CSU team continues to make progress on device and materials analysis. Modeling for increased device performance and the effects of processing conditions on properties of CdTe PV were investigated.

14 SOLAR ENERGY↗

DOE OSTI2010

Evaluation of Reformer Produced Synthesis Gas for Emissions Reductions in Natural Gas Reciprocating Engines

Rolls-Royce Fuel Cell Systems (US) Inc. (RRFCS) has developed a system that produces synthesis gas from air and natural gas. A near-term application being considered for this technology is synthesis gas injection into reciprocating engines for reducing NO{sub x} emissions. A proof of concept study using bottled synthesis gas and a two-stroke reciprocating engine showed that injecting small amounts of high-flammable content synthesis gas significantly improved combustion stability and enabled leaner engine operation resulting in over 44% reduction in NO{sub x} emissions. The actual NO{sub x} reduction that could be achieved in the field is expected to be engine specific, and in many cases may be even greater. RRFCS demonstrated that its synthesis gas generator could produce synthesis gas with the flammable content that was successfully used in the engine testing. An economic analysis of the synthesis gas approach estimates that its initial capital cost and yearly operating cost are less than half that of a competing NO{sub x} reduction technology, Selective Catalytic Reduction. The next step in developing the technology is an integrated test of the synthesis gas generator with an engine to obtain reliability data for system components and to confirm operating cost. RRFCS is actively pursuing opportunities to perform the integrated test. A successful integrated test would demonstrate the technology as a low-cost option to reduce NO{sub x} emissions from approximately 6,000 existing two-stroke, natural gas-fired reciprocating engines used on natural gas pipelines in North America. NO{sub x} emissions reduction made possible at a reasonable price by this synthesis gas technology, if implemented on 25% of these engines, would be on the order of 25,000 tons/year.

03 NATURAL GAS↗

DOE OSTI2010

Transferring PACE Assessments Upon Home Sale

A significant barrier to investing in renewable energy and comprehensive energy efficiency improvements to homes across the country is the initial capital cost. Property Assessed Clean Energy (PACE) financing is one of several new financial models broadening access to clean energy by addressing this upfront cost issue. Recently, the White House cited PACE programs as an important element of its 'Recovery through Retrofit' plan. The residential PACE model involves the creation of a special clean energy financing district that homeowners elect to opt into. Once opted in, the local government (usually at the city or county level) finances the upfront investment of the renewable energy installation and/or energy efficiency improvements. A special lien is attached to the property and the assessment is paid back as a line item on the property tax bill. As of April 2010, 17 states have passed legislation to allow their local governments to create PACE programs, two already have the authority to set up PACE programs, and over 10 additional states are actively developing enabling legislation. This policy brief analyzes one of the advantages of PACE, which is the transferability of the special assessment from one homeowner to the next when the home is sold. This analysis focuses on the potential for the outstanding lien to impact the sales negotiation process, rather than the legal nature of the lien transfer itself. The goal of this paper is to consider what implications a PACE lien may have on the home sales negotiation process so that it can be addressed upfront rather than risk a future backlash to PACE programs. If PACE programs do expand at a rapid rate, the chances are high that there will be other cases where prospective buyers uses PACE liens to negotiate lower home prices or require repayment of the lien as a condition of sale. As a result, PACE programs should highlight this issue as a potential risk factor for the sake of full disclosure. A good example of this is in Boulder County where the following statement is included in the ClimateSmart PACE program materials: 'Please Note: There is no legal requirement that the loan be paid off when you refinance or sell your home. However, this may be an item subject to negotiation with a future buyer and may also be a matter of negotiation with the mortgage lender.' Such candid disclosure for what might be a low risk event can be debated. However, a selling point of PACE programs is the transferability of the lien to the new homeowner. To the degree this benefit is questioned, PACE programs may end up looking more like home equity loan financing, with the associated debt repaid at closing, rather than property-based financing that remains with the improved home. While it is possible that upfront disclosure might negatively impact participation rates in PACE programs, it also will protect the integrity of a PACE program in later years if such situations come to pass. Ideally, this will become less of an issue over time as more homebuyers understand the positive economic and societal benefits of owning a home with clean energy features.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗

DOE OSTI2010

Interim Report: Air-Cooled Condensers for Next Generation Geothermal Power Plants Improved Binary Cycle Performance

As geothermal resources that are more expensive to develop are utilized for power generation, there will be increased incentive to use more efficient power plants. This is expected to be the case with Enhanced Geothermal System (EGS) resources. These resources will likely require wells drilled to depths greater than encountered with hydrothermal resources, and will have the added costs for stimulation to create the subsurface reservoir. It is postulated that plants generating power from these resources will likely utilize the binary cycle technology where heat is rejected sensibly to the ambient. The consumptive use of a portion of the produced geothermal fluid for evaporative heat rejection in the conventional flash-steam conversion cycle is likely to preclude its use with EGS resources. This will be especially true in those areas where there is a high demand for finite supplies of water. Though they have no consumptive use of water, using air-cooling systems for heat rejection has disadvantages. These systems have higher capital costs, reduced power output (heat is rejected at the higher dry-bulb temperature), increased parasitics (fan power), and greater variability in power generation on both a diurnal and annual basis (larger variation in the dry-bulb temperature). This is an interim report for the task ‘Air-Cooled Condensers in Next- Generation Conversion Systems’. The work performed was specifically aimed at a plant that uses commercially available binary cycle technologies with an EGS resource. Concepts were evaluated that have the potential to increase performance, lower cost, or mitigate the adverse effects of off-design operation. The impact on both cost and performance were determined for the concepts considered, and the scenarios identified where a particular concept is best suited. Most, but not all, of the concepts evaluated are associated with the rejection of heat. This report specifically addresses three of the concepts evaluated: the use of recuperation, the use of turbine reheat, and the non-consumptive use of EGS make-up water to supplement heat rejection

15 GEOTHERMAL ENERGY↗

DOE OSTI2011

DOE Hydrogen, Fuel Cells and Infrastructure Technologies Program Integrated Hydrogen Production, Purification and Compression System

The project was started in April 2005 with the objective to meet the DOE target of delivered hydrogen of <$1.50/gge, which was later revised by DOE to $2-$3/gge range for hydrogen to be competitive with gasoline as a fuel for vehicles. For small, on-site hydrogen plants being evaluated at the time for refueling stations (the 'forecourt'), it was determined that capital cost is the main contributor to the high cost of delivered hydrogen. The concept of this project was to reduce the cost by combining unit operations for the entire generation, purification, and compression system (refer to Figure 1). To accomplish this, the Fluid Bed Membrane Reactor (FBMR) developed by MRT was used. The FBMR has hydrogen selective, palladium-alloy membrane modules immersed in the reformer vessel, thereby directly producing high purity hydrogen in a single step. The continuous removal of pure hydrogen from the reformer pushes the equilibrium 'forward', thereby maximizing the productivity with an associated reduction in the cost of product hydrogen. Additional gains were envisaged by the integration of the novel Metal Hydride Hydrogen Compressor (MHC) developed by Ergenics, which compresses hydrogen from 0.5 bar (7 psia) to 350 bar (5,076 psia) or higher in a single unit using thermal energy. Excess energy from the reformer provides up to 25% of the power used for driving the hydride compressor so that system integration improved efficiency. Hydrogen from the membrane reformer is of very high, fuel cell vehicle (FCV) quality (purity over 99.99%), eliminating the need for a separate purification step. The hydride compressor maintains hydrogen purity because it does not have dynamic seals or lubricating oil. The project team set out to integrate the membrane reformer developed by MRT and the hydride compression system developed by Ergenics in a single package. This was expected to result in lower cost and higher efficiency compared to conventional hydrogen production technologies. The overall objective was to develop an integrated system to directly produce high pressure, high-purity hydrogen from a single unit, which can meet the DOE cost H2 cost target of $2 - $3/gge when mass produced. The project was divided into two phases with the following tasks and corresponding milestones, targets and decision points. Phase 1 - Task 1 - Verify feasibility of the concept, perform a detailed techno-economic analysis, and develop a test plan; and Task 2: Build and experimentally test a Proof of Concept (POC) integrated membrane reformer/metal hydride compressor system. Phase 2 - Task 3: Build an Advanced Prototype (AP) system with modifications based on POC learning and demonstrate at a commercial site; and Task 4: Complete final product design for mass manufacturing units capable of achieving DOE 2010 H2 cost and performance targets.

02 PETROLEUM↗

DOE OSTI2011

Hydrogen pipeline compressors annual progress report.

The objectives are: (1) develop advanced materials and coatings for hydrogen pipeline compressors; (2) achieve greater reliability, greater efficiency, and lower capital in vestment and maintenance costs in hydrogen pipeline compressors; and (3) research existing and novel hydrogen compression technologies that can improve reliability, eliminate contamination, and reduce cost. Compressors are critical components used in the production and delivery of hydrogen. Current reciprocating compressors used for pipeline delivery of hydrogen are costly, are subject to excessive wear, have poor reliability, and often require the use of lubricants that can contaminate the hydrogen (used in fuel cells). Duplicate compressors may be required to assure availability. The primary objective of this project is to identify, and develop as required, advanced materials and coatings that can achieve the friction, wear, and reliability requirements for dynamically loaded components (seal and bearings) in high-temperature, high-pressure hydrogen environments prototypical of pipeline and forecourt compressor systems. The DOE Strategic Directions for Hydrogen Delivery Workshop identified critical needs in the development of advanced hydrogen compressors - notably, the need to minimize moving parts and to address wear through new designs (centrifugal, linear, guided rotor, and electrochemical) and improved compressor materials. The DOE is supporting several compressor design studies on hydrogen pipeline compression specifically addressing oil-free designs that demonstrate compression in the 0-500 psig to 800-1200 psig range with significant improvements in efficiency, contamination, and reliability/durability. One of the designs by Mohawk Innovative Technologies Inc. (MiTi{reg_sign}) involves using oil-free foil bearings and seals in a centrifual compressor, and MiTi{reg_sign} identified the development of bearings, seals, and oil-free tribological coatings as crucial to the successful development of an advanced compressor. MiTi{reg_sign} and ANL have developed potential coatings for these rigorous applications; however, the performance of these coatings (as well as the nickel-alloy substrates) in high-temperature, high-speed hydrogen environments is unknown at this point.

08 HYDROGEN↗

DOE OSTI2011

Safety Design Strategy for the Advanced Test Reactor Primary Coolant Pump and Motor Replacement Project

In accordance with the requirements of U.S. Department of Energy (DOE) Order 413.3B, “Program and Project Management for the Acquisition of Capital Assets,” safety must be integrated into the design process for new or major modifications to DOE Hazard Category 1, 2, and 3 nuclear facilities. The intended purpose of this requirement involves the handling of hazardous materials, both radiological and chemical, in a way that provides adequate protection to the public, workers, and the environment. Requirements provided in DOE Order 413.3B and DOE Order 420.1B, “Facility Safety,” and the expectations of DOE-STD-1189-2008, “Integration of Safety into the Design Process,” provide for identification of hazards early in the project and use of an integrated team approach to design safety into the facility. This safety design strategy provides the basic safety-in-design principles and concepts that will be used for the Advanced Test Reactor Reliability Sustainment Project. While this project does not introduce new hazards to the ATR, it has the potential for significant impacts to safety-related systems, structures, and components that are credited in the ATR safety basis and are being replaced. Thus the project has been determined to meet the definition of a major modification and is being managed accordingly.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗

DOE OSTI2011

Safety Design Strategy for the Advanced Test Reactor Emergency Firewater Injection System Replacement Project

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗

DOE OSTI2011

Safety Design Strategy for the Advanced Test Reactor Diesel Bus (E-3) and Switchgear Replacement Project

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗

DOE OSTI2011

North Dakota Refining Capacity Study

According to a 2008 report issued by the United States Geological Survey, North Dakota and Montana have an estimated 3.0 to 4.3 billion barrels of undiscovered, technically recoverable oil in an area known as the Bakken Formation. With the size and remoteness of the discovery, the question became 'can a business case be made for increasing refining capacity in North Dakota?' And, if so what is the impact to existing players in the region. To answer the question, a study committee comprised of leaders in the region's petroleum industry were brought together to define the scope of the study, hire a consulting firm and oversee the study. The study committee met frequently to provide input on the findings and modify the course of the study, as needed. The study concluded that the Petroleum Area Defense District II (PADD II) has an oversupply of gasoline. With that in mind, a niche market, naphtha, was identified. Naphtha is used as a diluent used for pipelining the bitumen (heavy crude) from Canada to crude markets. The study predicted there will continue to be an increase in the demand for naphtha through 2030. The study estimated the optimal configuration for the refinery at 34,000 barrels per day (BPD) producing 15,000 BPD of naphtha and a 52 percent refinery charge for jet and diesel yield. The financial modeling assumed the sponsor of a refinery would invest its own capital to pay for construction costs. With this assumption, the internal rate of return is 9.2 percent which is not sufficient to attract traditional investment given the risk factor of the project. With that in mind, those interested in pursuing this niche market will need to identify incentives to improve the rate of return.

02 PETROLEUM↗

DOE OSTI2011

Recovery Act: Federspiel Controls (now Vigilent) and State of California Department of General Services Data Center Energy Efficient Cooling Control Demonstration. Final technical project report

Eight State of California data centers were equipped with an intelligent energy management system to evaluate the effectiveness, energy savings, dollar savings and benefits that arise when powerful artificial intelligence-based technology measures, monitors and actively controls cooling operations. Control software, wireless sensors and mesh networks were used at all sites. Most sites used variable frequency drives as well. The system dynamically adjusts temperature and airflow on the fly by analyzing real-time demands, thermal behavior and historical data collected on site. Taking into account the chaotic interrelationships of hundreds to thousands of variables in a data center, the system optimizes the temperature distribution across a facility while also intelligently balancing loads, outputs, and airflow. The overall project will provide a reduction in energy consumption of more than 2.3 million kWh each year, which translates to $240,000 saved and a reduction of 1.58 million pounds of carbon emissions. Across all sites, the cooling energy consumption was reduced by 41%. The average reduction in energy savings across all the sites that use VFDs is higher at 58%. Before this case study, all eight data centers ran the cooling fans at 100% capacity all of the time. Because of the new technology, cooling fans run at the optimum fan speed maintaining stable air equilibrium while also expending the least amount of electricity. With lower fan speeds, the life of the capital investment made on cooling equipment improves, and the cooling capacity of the data center increases. This case study depicts a rare technological feat: The same process and technology worked cost effectively in eight very different environments. The results show that savings were achieved in centers with diverse specifications for the sizes, ages and types of cooling equipment. The percentage of cooling energy reduction ranged from 19% to 78% while keeping temperatures substantially within the limits recommended by the American Society of Heating, Refrigeration, and Air-Conditioning Engineers (ASHRAE) for data center facilities.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2011

Light Water Reactor Sustainability Program Power Uprate Research and Development Strategy

The economic incentives for low-cost electricity generation will continue to drive more plant owners to identify safe and reliable methods to increase the electrical power output of the current nuclear power plant fleet. A power uprate enables a nuclear power plant to increase its electrical output with low cost. However, power uprates brought new challenges to plant owners and operators. These include equipment damage or degraded performance, and unanticipated responses to plant conditions, etc. These problems have arisen mainly from using dated design and safety analysis tools and insufficient understanding of the full implications of the proposed power uprate or from insufficient attention to detail during the design and implementation phase. It is essential to demonstrate that all required safety margins have been properly retained and the existing safety level has been maintained or even increased, with consideration of all the conditions and parameters that have an influence on plant safety. The impact of the power uprate on plant life management for long term operation is also an important issue. Significant capital investments are required to extend the lifetime of an aging nuclear power plant. Power uprates can help the plant owner to recover the investment costs. However, plant aging issues may be aggravated by the power uprate due to plant conditions. More rigorous analyses, inspections and monitoring systems are required.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

DOE OSTI2011

RISK-INFORMED BALANCING OF SAFETY, NONPROLIFERATION, AND ECONOMICS FOR THE SFR

A substantial barrier to the implementation of Sodium-cooled Fast Reactor (SFR) technology in the short term is the perception that they would not be economically competitive with advanced light water reactors. With increased acceptance of risk-informed regulation, the opportunity exists to reduce the costs of a nuclear power plant at the design stage without applying excessive conservatism that is not needed in treating low risk events. In the report, NUREG-1860, the U.S. Nuclear Regulatory Commission describes developmental activities associated with a risk-informed, scenario-based technology neutral framework (TNF) for regulation. It provides quantitative yardsticks against which the adequacy of safety risks can be judged. We extend these concepts to treatment of proliferation risks. The objective of our project is to develop a risk-informed design process for minimizing the cost of electricity generation within constraints of adequate safety and proliferation risks. This report describes the design and use of this design optimization process within the context of reducing the capital cost and levelized cost of electricity production for a small (possibly modular) SFR. Our project provides not only an evaluation of the feasibility of a risk-informed design process but also a practical test of the applicability of the TNF to an actual advanced, non-LWR design. The report provides results of five safety related and one proliferation related case studies of innovative design alternatives. Applied to previously proposed SFR nuclear energy system concepts We find that the TNF provides a feasible initial basis for licensing new reactors. However, it is incomplete. We recommend improvements in terms of requiring acceptance standards for total safety risks, and we propose a framework for regulation of proliferation risks. We also demonstrate methods for evaluation of proliferation risks. We also suggest revisions to scenario-specific safety risk acceptance standards, particularly concerning seismic and aircraft impactrelated risks. Most importantly, within the context of the TNF historical SFR safety concerns about energetic core disruptive accidents are seen to be unimportant, but those of rare scenarios mentioned above are seen to be of dominant concern. In terms of proliferation risks the SFR energy system is seen not to be of considerably greater concern than with other nuclear power technologies, providing that highly effective safeguards are employed. We find the economic performance of proposed SFRs likely, due to the problems of using sodium as a coolant, to be inferior to those of LWRs unless they can be credited for services to improve nuclear waste disposal, nuclear fuel utilization and proliferation risk reductions. None of the design innovations investigated offers the promise to reverse this conclusion. The most promising innovation investigated is that of improving the plant's thermodynamic efficiency via use of the supercritical CO{sub 2} (rather than steam Rankine) power conversion system. We were unable to reach conclusions about the economic and proliferation risk implications of competing nuclear fuel processing methods, as available designs are too little developed to justify any such results. Overall, we find the SFR to be a promising alternative to LWRs should the conditions governing the valuation change substantially from current ones.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

DOE OSTI2011

Modeling and experimental results for condensing supercritical CO2 power cycles.

This Sandia supported research project evaluated the potential improvement that 'condensing' supercritical carbon dioxide (S-CO{sub 2}) power cycles can have on the efficiency of Light Water Reactors (LWR). The analytical portion of research project identified that a S-CO{sub 2} 'condensing' re-compression power cycle with multiple stages of reheat can increase LWR power conversion efficiency from 33-34% to 37-39%. The experimental portion of the project used Sandia's S-CO{sub 2} research loop to show that the as designed radial compressor could 'pump' liquid CO{sub 2} and that the gas-cooler's could 'condense' CO{sub 2} even though both of these S-CO{sub 2} components were designed to operate on vapor phase S-CO{sub 2} near the critical point. There is potentially very high value to this research as it opens the possibility of increasing LWR power cycle efficiency, above the 33-34% range, while lowering the capital cost of the power plant because of the small size of the S-CO{sub 2} power system. In addition it provides a way to incrementally build advanced LWRs that are optimally designed to couple to S-CO{sub 2} power conversion systems to increase the power cycle efficiency to near 40%.

24 POWER TRANSMISSION AND DISTRIBUTION↗

DOE OSTI2010

Evaluation of Reformer Produced Synthesis Gas for Emissions Reductions in Natural Gas Reciprocating Engines

Rolls-Royce Fuel Cell Systems (US) Inc. (RRFCS) has developed a system that produces synthesis gas from air and natural gas. A near-term application being considered for this technology is synthesis gas injection into reciprocating engines for reducing NOx emissions. A proof of concept study using bottled synthesis gas and a two-stroke reciprocating engine showed that injecting small amounts of highflammables content synthesis gas significantly improved combustion stability and enabled leaner engine operation resulting in over 44% reduction in NOx emissions. The actual NOx reduction that could be achieved in the field is expected to be engine specific, and in many cases may be even greater. RRFCS demonstrated that its synthesis gas generator could produce synthesis gas with the flammables content that was successfully used in the engine testing. An economic analysis of the synthesis gas approach estimates that its initial capital cost and yearly operating cost are less than half that of a competing NOx reduction technology, Selective Catalytic Reduction. The next step in developing the technology is an integrated test of the synthesis gas generator with an engine to obtain reliability data for system components and to confirm operating cost. RRFCS is actively pursuing opportunities to perform the integrated test. A successful integrated test would demonstrate the technology as a low-cost option to reduce NOx emissions from approximately 6,000 existing two-stroke, natural gas-fired reciprocating engines used on natural gas pipelines in North America. NOx emissions reduction made possible at a reasonable price by this synthesis gas technology, if implemented on 25% of these engines, would be on the order of 25,000 tons/year.

03 NATURAL GAS↗