General Public Report

CATILaC: ComputeR Aided Techniques for Identifying Latent Conditions

Program: 

Type: 

  • TR

RPT. No.: 

2

Authors:: 

K. Marchinkowski
R.Weil
G.E. Apostolakis

Report Date: 

April 2001

Overview

Introduction to the CATILaC Methodology

By understanding the way that a facility coordinates the work it does, failure events can be placed into a broader organizational context. Once the organizational context is understood, steps can be taken to reduce the possibility of common-cause organizational failures. When this type of analysis is done in the context of a traditional Root Cause Analysis program, substantial insight into the possible causes of operational incidents can be obtained. This software package is designed to guide the user through the process of placing failure events into their organizational context. In doing so, the causes of the events and the human and hardware failures or deficiencies that lead to them will be better understood. Better corrective actions can be developed for all levels of the organization.

The methodology involves both understanding what happened during the course of the event and identifying the hardware failures that contributed to its occurrence. To do this the analyst must identify the sequence of failures that occurred and the causes for each, locate the initiating, or trigger, event, and find the latent failures that became active during the event. Once the event is understood, the human contributions to each of the hardware factors must be identified and analyzed. During the analysis, deficient tasks within work processes are identified. By doing this, the latent conditions that led to the event can be discovered. Figure 1 shows how human contributions are linked to fallible decisions/organizational factors.

CATILaC is focused on hardware failures and the human contributions that cause them rather than on operator actions that contribute to the event. Operations at a nuclear plant, especially post-trigger recovery actions, do not lend themselves to this type of work process analysis. Although it can be done using this software (see discussion of how to include operator contributions in Appendix I), there are other, more complete methods available to do that type of analysis.

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Aerodynamic Design of Turbine for S-CO₂ Brayton Cycle

Program: 

Type: 

  • TR

RPT. No.: 

3

Authors:: 

Y. Wang
M.J. Driscoll

Report Date: 

June 2003

 

Introduction

The supercritical CO2 (S-CO2) Brayton cycle is proposed for Generation IV reactor applications because of its simplicity, high efficiency, compactness and thus potential to cost reduction. To achieve an attractive cycle efficiency (~ 45%), highly efficient cycle components must be guaranteed. Hence the turbine, the main design objective is to achieve high efficiency while maintaining the turbine at a reasonable size. Due to the high power and high mass flow rate demands of the present application an axial-flow turbine was employed. Two NASA Glenn Research Center (GRC) developed codes (TURBAN and AXOD) were modified and implemented to perform the aerodynamic design. TURBAN is a preliminary axial-flow turbine design code. AXOD is a multi-stage turbine off-design performance code. Both codes were developed for airbreathing aircraft engine and ideal gas applications. Since CO2 exhibits significantly nonideal behavior under S-CO2 cycle operating conditions, both codes were modified to apply for real gas applications. The NIST pure fluid properties database was implemented into the codes for this purpose. TURBAN-MOD and AXOD-MOD are the modified versions respectively. TURBAN-MOD determines the stage velocity diagrams, stage and overall efficiencies and simple blade geometry at a design-point. AXOD-MOD calculates the off-design performance at optimum incidence angles based on the design-point and generates characteristic maps. The off-design performance maps can be used for cycle control analysis. 

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h1 report title: 

Aerodynamic Design of Turbine for S-CO₂ Brayton Cycle

Thermal Striping in LWR Piping Systems Progress Report: September 2001 through August 2002

Program: 

Type: 

  • PR

RPT. No.: 

14

Authors:: 

L-W. Hu
M.S. Kazimi
A Sonin

Report Date: 

August 2002

Abstract

This report summarizes the progress of the MIT/TEPCO project entitled “Thermal Striping in LWR Piping Systems” during the second year. Progress during the first year was summarized in the MIT CANES report MITR-NSP-TR-007. Thermal striping has raised safety concerns due to incidents at some nuclear power plants. The current study investigates thermal striping at tee junctions of light water coolant systems through numerical simulations. A series of benchmark and sensitivity study was performed through the first and second year of this project.

Further improved results were obtained from FLUENT simulations during the second year due to several refinements. These include: use of a smaller time step (~ 1 ms vs. 10-50 ms), an improved sub-grid scale model, a refined tee junction geometry, and the use of a central –differencing spatial discretization scheme. Sensitivity studies of these refinements and the flow velocity ratios are described in this report.

A new version of FLUENT, FLUENT6.0, was released in January 2002. All calculations that were performed since March 2002 used FLUENT6.0. Although modifications in FLUENT6.0 do not involve enhancements of LES subgrid models, one feature related to LES in FLUENT6.0 is the incorporation of the second-order accurate central-differencing scheme. The central-differencing scheme is available for the momentum equations when using the LES turbulence model. This scheme provides improved accuracy for LES calculations. A sensitivity study was performed to compare the calculated results using the second order upwind and the central differencing schemes. Comparisons of the normalized temperatures show that the central differencing scheme produces significantly higher temperature fluctuations than the secondary upwind scheme at all three azimuthal positions. It is also noted to have a significant effect in turbulent mixing which in turn promotes a more uniform temperature distribution in the main coolant flow down stream the tee junction. However, one problem associated with use of the central-differencing scheme is that it can produce unbounded solutions and can lead to stability problems. Overshoot and undershoot of the calculated coolant temperatures were both found when the central-differencing scheme was chosen.

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Water for a Warming Climate: A Feasibility Study of Repurposing Diablo Canyon Nuclear Plant for Desalination

Program: 

Type: 

  • TR

RPT. No.: 

20

Authors:: 

A. T. Bouma, Q. J. Wie, J. E. Parsons, J. Buongiorno, J. H. Lienhard V

Report Date: 

July 2021

Executive Summary

We consider the techno-economic feasibility of constructing a large-scale reverse osmosis desalination plant at the Diablo Canyon Nuclear Power Plant (DCNPP). This arrangement integrates the desalination plant with the nuclear power plant by sharing infrastructure and receiving feedwater and power from the nuclear power plant, forming a water-power coproduction system.

A key challenge for continued operation of DCNPP and for any desalination plant is compliance with California’s regulations protecting marine organisms from large intake structures. We show how a new brushed-screen intake structure, serving both the nuclear power plant and the desalination plant, achieves compliance. Our understanding is that there are no other technical obstacles to DCNPP’s license extension. The cost of the new intake is reflected in the cost of power. In our design, warm condenser water from the nuclear power plant flows into the desalination plant, which consists of a pretreatment system similar to that of the existing small-scale desalination plant at Diablo Canyon, followed by a partial two-pass reverse osmosis system and remineralization. Depending on the scale of the plant, either the discharged brine from the desalination system may be commingled and diluted with the excess cooling water, using the existing plant outfall, or a new advanced high-energy diffuser system may be required.

The focus of our analysis is a hypothetical plant of the same size as the existing plant in Carlsbad, CA, but we also include additional analyses of significantly larger plants. When we consider the cost of desalinated water from this arrangement, compared to other desalination plants in California, we find that there are significant economic advantages for a DCNPP-desalination coproduction plant. At smaller scales, savings result primarily from reduced power costs and the sharing of the new intake and existing outfall structures. At larger plant capacities, there is potential for additional cost savings from economies of scale. However, at larger capacities, other challenges arise, including increased infrastructure needs, especially around the plant outfall, as well as practical challenges in siting and building a very large plant on the DCNPP premises.

Key findings of this study include:

  • The cost of electricity paid by the desalination plant is expected to be 5.4 cents per kWh, a significant reduction from the price of power purchased from the grid.
  • The levelized cost of water falls in a range from $0.77 to $0.98 per m3 of fresh water at the plant outlet, with distribution costs adding an additional $0.02 to $0.21 per m3 to transport the water an additional 20-185 km to offtakers. For comparison, the cost to build additional Carlsbad-sized plants in California as stand-alone desalination plants is approximately $1.84 per m3 of fresh water at the plant outlet.
  • Additional key data are shown in Table 1.

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h1 report title: 

A Feasibility Study of Repurposing Diablo Canyon Nuclear Plant for Desalination

Address: 

Massachusetts Institute of Technology, Cambridge, MA 02139

Can a Nuclear-Assisted Biofuels System Enable Liquid Biofuels as the Economic Low-carbon Replacement for All Liquid Fossil Fuels and Hydrocarbon Feedstocks and Enable Negative Carbon Emissions?

Program: 

Type: 

  • TR

RPT. No.: 

23

Authors:: 

Forsberg, C. W., Massachusetts Institute of Technology,
Dale, B. Michigan State University

Authors: 

Charles W. Forsberg

Report Date: 

April 2022

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Appendix: Can a Nuclear-Assisted Biofuels System Enable Liquid Biofuels as the Economic Low-carbon Replacement for All Liquid Fossil Fuels and Hydrocarbon Feedstocks and Enable Negative Carbon Emissions?

Program: 

Type: 

  • TR

RPT. No.: 

23

Authors:: 

C. W. Forsberg Massachusetts Institute of Technology
B. Dale Michigan State University

Report Date: 

April 2022

Abstract

This report integrates the results of a series of studies and workshops to address the question: Can a nuclear-assisted biofuels system enable liquid biofuels as the economic low-carbon replacement for all liquid fossil fuels and hydrocarbon feedstocks and simultaneously enable negative carbon emissions? “Economic” is defined as economically competitive relative to other low-carbon replacement options for crude oil. “All” refers to the capability to replace the 18 million barrels of oil per day used by the United States. “Nuclear-assisted” refers to the provision of massive quantities of low-carbon heat and hydrogen at the refinery to fully utilize the carbon content of the cellulosic biomass feedstocks for liquid hydrocarbon production.

A system is proposed that decarbonizes about half of the U.S. economy while improving long-term soil productivity and sequestering carbon from the atmosphere. In the U.S. almost half the energy consumed by the final customer is in the form of liquid hydrocarbons produced from crude oil. Liquid hydrocarbons are used as (1) an energy source, (2) a method for daily-to-seasonal energy storage, (3) a chemical feedstock, (4) a chemical reducing agent, (5) a method to enhance high-temperature heat transfer in many furnaces and industrial processes and (6) other purposes. As a consequence, the U.S. consumes ~18 million barrels of crude oil per day to produce liquid hydrocarbons. While there are substitutes for liquid hydrocarbons for some applications, our assessment is that the costs and difficulty will dramatically increase if liquid hydrocarbon use goes much below the equivalent of 10 million barrels per day of crude oil. New uses of liquid hydrocarbons to partly replace coal and natural gas could increase demand beyond the equivalent of 10 million barrels of oil per day.

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Address: 

Massachusetts Institute of Technology, Cambridge, MA 02139

The Value of Nuclear Microreactors in Providing Heat and Electricity to Alaskan Communities

Program: 

Type: 

  • TR

RPT. No.: 

192

Authors:: 

R. Macdonald and J.Parsons

Report Date: 

October 2021

Summary

We evaluated the system cost of providing electricity and heat to serve the load profiles of two types of Alaskan communities, and calculated the cost efficiency of including a nuclear microreactor in the generation portfolio. We employed a capacity expansion and dispatch model augmented to co-optimize heat and electricity generation. Since microreactor designs are still in development and the eventual capital and O&M costs are speculative, our strategy was to explore the outcomes across a wide range of capital costs, and find the range in which a microreactor is included in the least-cost portfolio and the range in which it is not. We call the boundary between the two the capital cost ceiling.

We have identified the microreactor capital cost ceiling under a range of assumptions and scenarios. This includes two different load profiles—one reflective of demand across Alaska’s Railbelt communities, and one reflective of demand at a remote Alaskan mine and neighbouring community. We assessed the impact of natural gas fuel availability, whether a community had a district heating network, future reductions in the capital cost of renewables, the price of fossil fuels, and, last-but-not-least, the need to reduce systemwide emissions.

Three factors appear to play a dominant role in setting the capital cost ceiling and answering whether a microreactor is likely to be a cost-efficient addition to the system. One of these is the availability of natural gas. Natural gas is a much cheaper source of energy than diesel fuel, and therefore the microreactor capital cost ceiling is significantly lower in communities where it is available. Most communities in the Alaskan Railbelt have access to natural gas, while few, if any, of the other communities do.

The second factor is the size of the heat load and the accessibility of a district heating network. In our results, the capital cost ceiling was much higher in scenarios where a microreactor’s waste heat was highly utilized. Communities in the Alaskan Railbelt have higher heat loads and select ones have accessible district heating networks, which facilitated the use of microreactor waste heat, and set the capital cost ceiling high. In contrast, a remote community anchored by a mine has a relatively smaller heat load, which would set the capital cost ceiling lower.

The third, and overwhelmingly most important factor, is the goal of emission reductions. Any modest emissions reduction target dramatically raised the capital cost ceiling for a microreactor, reflecting that the microreactor is very cost-efficient among low carbon options when heat and electricity are considered together. This conclusion holds broadly across both load profiles. We focused on CO2 emissions. However, we are aware that certain Railbelt communities face a critical need to reduce particulates and other criteria pollutants. Recognizing this would further boost the competitiveness of a microreactor.

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h1 report title: 

The Value of Nuclear Microreactors in Providing Heat and Electricity to Alaskan Communities

Address: 

Massachusetts Institute of Technology, Cambridge, MA 02139

Overnight Capital Cost of the Next AP1000

Program: 

Type: 

  • TR

RPT. No.: 

193

Authors:: 

Koroush Shirvan

Report Date: 

March 2022

Executive Summary

Nuclear energy has been reinvigorated as a scalable and reliable pathway to produce carbon-free energy by governments and companies that are pursuing deep decarbonization targets. One such technology developed during the last four decades and under deployment/deployed in the U.S. and China, respectively, is the 1150 MW-electric AP1000 Generation III+ nuclear power plant. AP1000 is now a proven technology that is able to produce almost 10,000 GWh of clean energy per year with a plant lifetime that can be readily extended to 80 years and beyond. Before the fracking boom that led to the low price of natural gas, AP1000 was primed to be a major nuclear technology with over 20 units under operation by this decade. However, the availability of cheaper alternative energy sources along with First-Of-A-Kind (FOAK) cost experience and schedule delays with AP1000, particularly in the U.S., have led to only 2 plants being currently under construction at the Vogtle site in the U.S. For the energy sector, the Vogtle project has been a clear example of why nuclear energy is not competitive with alternative energy sources with a total price tag of $28 billion dollars as of July 2021 and rising for the two 1150 MWe plants (~$14+ billion for each reactor, inclusive of owner costs and financing)...

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h1 report title: 

Overnight Capital Cost of the Next AP1000

Address: 

Massachusetts Institute of Technology, Cambridge, MA 02139

Capital Cost Evaluation of Advanced Water-Cooled Reactor Designs With Consideration of Uncertainty and Risk

Program: 

RPT. No.: 

194

Authors:: 

W. Robb Stewart
K. Shirvan

Report Date: 

June 2022

Abstract

Decarbonization incentives present an enormous market opportunity for the nuclear industry. To stay within the 1.5°C limit by 2050, across a range of scenarios, the IPCC forecasted a 2.5x average increase in global nuclear generation. High capital costs and the risk of overruns and delays may prevent the industry from realizing this new potential. Recent nuclear projects in the U.S. and Europe have averaged cost overruns more than 2x the original estimate. However, new suites of reactor architectures are under development, and they may solve some or all elements of the cost problem. These new architectures leverage modularization, intra-plant learning rates, passive safety, advanced construction, and advanced manufacturing in their endeavor to lower capital costs. This thesis systematically analyzes the cost saving potential of each of these strategies for eight unique reactor architectures. The aim was to understand which architectures and strategies have the greatest potential to reduce cost and risk to cost overruns, and then, apply that understanding to help utilities, policymakers, and other stakeholders in investment decision making and long-term planning...

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h1 report title: 

Capital Cost Evaluation of Advanced Water-Cooled Reactor Designs With Consideration of Uncertainty and Risk

Address: 

Massachusetts Institute of Technology, Cambridge, MA 02139

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