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1.06: Improved Construction and Economy of Small LWRs
2:00pm - 3:30pm
Session Chair: Bassam Khuwaileh, University of Sharjah, United Arab Emirates
Is embedding the reactor building below grade a cost-effective proposition?
Enrique Velez Lopez, Kennard Johnston, Jacopo Buongiorno, Koroush Shirvan, Herbert H Einstein
Massachusetts Institute of Technology
The construction cost of reactor buildings has escalated substantially over time primarily for three reasons. First, new safety requirements, such as the post-9/11 airplane crash measures, have been imposed. Second, labor rates for construction workers and the cost of raw materials such as steel for rebar and cement for concrete have increased. Third, the deployment of new plant designs, such as AP1000 and EPR, has been plagued by first-of-a-kind challenges and a general loss of construction know-how by the nuclear industry in the U.S. and Western Europe. Embedding the reactor building below grade is a potential approach to reduce the construction cost of new plants, be they large LWRs, SMRs or Generation-IV designs. There are important trade-offs. Embedment of a reactor building requires a much larger excavation effort than is necessary for above-grade plants. However, embedded buildings are subject to lower loads during earthquakes and possibly also airplane crashes, thus requiring less reinforcement. As such, the cost of the building itself, i.e., without the excavation costs, can be significantly lower. In this paper we analyze a modularized, silo-type reactor building (i.e., the type used, for example, in GEH’s BWRX-300 design) for a set of reference seismic loads at sites with both soil and rock stratigraphy. The comparison includes a completely embedded design, a partially-embedded design and an above-ground design. The level of reinforcement required is determined from FEM analysis of the building, and the cost of constructing the external wall of the buildings is estimated from productivity data, labor rates and materials costs obtained from industry sources. It is found that there are some building layouts and sites where a substantial cost reduction for the external wall of an embedded reactor building may be realized.
Validation of Numerical Models for Seismic Fluid-Structure Interaction Analysis of Advanced Reactors
Faizan Ul Haq Mir1, Ching-Ching Yu1, Hasan Charkas2, Andrew Whittaker1
1University at Buffalo; 2Electric Power Research Institute
Some advanced reactor designs use liquid metals as the primary coolant. Numerical analysis is the only plausible pathway to the seismic design and qualification of these reactor vessels and their internals because available analytical solutions for the seismic response of submerged components are insufficient and the vessels are too large and expensive to undergo physical testing. For numerical analysis, verified and validated numerical models are needed to capture the interaction of the vessel, its contained fluid and the internal equipment: fluid-structure interaction. At present, there are no verified and validated numerical models for seismic fluid-structure interaction of advanced reactors that can predict responses over a wide range of three-component earthquake shaking. To generate experimental data that could be used to validate numerical models in commercial and open-source finite element codes, a two-phase program of experiments is being performed on a 6 degree-of-freedom earthquake simulator at the University at Buffalo as part of an ARPA-E project. A scaled model of a base-supported reactor vessel was tested in the first phase. The second-phase testing involved simplified representations of internals submerged in fluid in the tank, to study added mass, damping and coupling effects. The impact of seismic (base) isolation is being studied initially using earthquake simulator inputs that assume the presence of a virtual isolation system. The paper presents an overview of the test specimen, the testing program and the instrumentation. Data from the first phase of experiments is presented, together with preliminary numerical simulations. The data from all the ARPA-E experiments will be archived for later use by analysts and engineers tasked with validating numerical models to be used to design nuclear (or mechanical) systems involving fluids and structures.
Can Nuclear Replace Coal?
Indian Institute of Technology, Bombay
The oil shock of 1973 provided the impetus for countries like France, Sweden and South Korea to switch to nuclear and reduce their dependence on imported oil. The current climate change crisis offers a similar opportunity for nuclear power plants to became a clean alternative to coal. The high capital cost of nuclear is a major barrier for its growth. In this paper, we reviewed the
recent costs of building new nuclear plants to find which reactor design has the highest potential of being built economically. The cost of the new plants being built in UAE, Bangladesh, Turkey, Pakistan and Egypt indicate that new PWRs are likely to cost about $5500-6000/kW. Russia and China can probably build new plants within their own country for less than $3500/kW. The lowest
cost of new nuclear is in India where PHWRs are being built at less than $2500/kW. Considering the technological challenges, we estimate that Generation IV reactors will cost significantly more than existing reactors. It appears that the best chance of building economical nuclear power may
lie in the simple design of Generation I plutonium production reactors rather than the sophisticated designs of Generation IV reactors.
Impact of Core Power Density on Economics of a Small Integral PWR
Assil Anis Halimi, Koroush Shirvan
Massachusetts Institute of Technology
Increasing the core power density of nuclear reactors allows higher power generation from the same volume, reducing the cost of the plant. Assuming standard 17x17 Pressurized Water Reactor (PWR) fuel assemblies with enrichment below 5%, a parametric study on core power density of an integral PWR is performed. The reference core design is rated at 60 kW/L and composed of 77 reduced-height fuel assemblies. The reactivity control during normal operation is assumed to utilize soluble boron and fuel burnable poisons. The commercial STUDSVIK code package is used to design cores ranging from 20 kW/L to 170 kW/L. This range results in respective output powers between 50 to 400 MWe for an assumed 32 % plant thermal efficiency. Core safety parameters such as peaking factors, Minimum Departure from Nucleate Boiling Ratio (MDNBR) and maximum fuel temperatures are evaluated for all designs. Economic evaluation of lifetime-levelized unit costs for the Fuel Cycle (FC), Operation and Maintenance (O&M) and capital expenditures was performed as a function of power density. Multi batch Fuel Cycle costs and burnups are evaluated using linear reactivity model (LRM). The relatively low core discharge burnup (32 MWD/kgU) leads to high lifetime-levelized fuel cycle unit cost for the reference core. However, increase in power density allows significant reduction in operation and maintenance and capital unit costs. At higher costs, low power density designs show long cycle lengths up to 14 years per cycle. Such long cycles could be an attractive option for remote locations or countries with limited nuclear infrastructure.