Nuclear Power Generation: Water Needs and Environmental Impacts

Transcription

1 Nuclear Power Generation: Water Needs and Environmental Impacts Nebiyu Tiruneh, Richard Raione, Hosung Ahn, Mark McBride, Joseph Giacinto United States Nuclear Regulatory Commission 2011 GROUNDWATER PROTECTION COUNCIL ANNUAL FORUM Atlanta, GA September 24-28,

2 Outline Introduction The Regulatory Framework Hydrologic Safety Review Hydrologic Environmental Review Nuclear Power Generation in the United States Hydrologic Safety Analysis of Radioactive Liquid Effluents Conceptual Site Models and Modeling Thermoelectric Power Generation and Water Needs Projected Growth in Thermoelectric Energy Generation Thermoelectric Power Generation Water Needs Water Withdrawal and Water Consumption Regional Climatic Variability and Water Demand Availability of Fresh Water Sources Water Withdrawal Trends Power Generation Impacts on Water Resources Thermal Pollution Radioactive Effluents Conclusions 2

3 Introduction Brief History of the U.S. NRC Atomic Energy Act of 1954 under section 103 enabled licensing of nuclear power plants for civilian use. The Energy Reorganization Act of establishment of the U.S. NRC in The Commission led by five appointed commissioners, one of them is appointed Chairman. Approved many licenses and currently there are 104 plants in operation. Operating plants licensed under 10 CFR Part 50 construction permit and operating license. 10 CFR Part 52 adopted in 1989 has provisions for COL, ESP, and DC 3

4 Introduction Terms COL Combined Operating License provides approval for construction and operation valid for a period of 40 years from the date of the Commission finding. COL can be renewed for an additional 20 years at the end of the initial licensing period. ESP Early Site Permit provides approval for one or more sites independent of a reactor design. the review includes site safety, environmental protection, and emergency planning, independent of a specific nuclear reactor design or application for a construction permit or combined license. is valid for 10 to 20 years from the date of issuance, and can be renewed for an additional 10 to 20 years. DC Design Certification approval of standardized reactor design. 4

5 The Regulatory Framework Safety Review: Determining the safe operation of the proposed plant under a variety of adverse conditions with appropriate provisions for mitigation and emergency procedures. Environmental Review: Performed to assess the impacts of construction and operation of a plant on the environment. Regulations: Atomic Energy Act, Regulations (10 CFR), the National Environmental Policy Act (NEPA). Clean Water Act, Guidance Documents: Standard Review Plan (SRP), Environmental Standard Review Plan (ESRP), Regulatory Guides (RG), National Standards, and scientific analyses. Cooperating Agencies: Federal Agencies such as EPA, and USACE Public Involvement: Scoping meetings, opportunity to intervene through hearings. Decision: The Commission, the Advisory Committee on Reactor Safeguards (ACRS). The Atomic Safety Licensing Board Panel (ASLBP). 5

6 Hydrologic Safety Review Hydrologic Description Interface of the plant with he hydrosphere, causal mechanisms, Conceptual Site Models (CSM) Floods Flood causing mechanisms, history, onsite flooding Probable Maximum Flood (PMF) on Streams and Rivers Potential Dam Failures Probable Maximum Surge and Seiche Flooding Probable Maximum Tsunami Flooding Ice Effects Cooling Water Canals and Reservoirs Channel Diversions Flooding Protection Requirements Low Water Considerations Groundwater Regional and local, aquifers, water use and quality Accidental Releases of Radioactive Liquid Effluents in Ground and Surface Waters Postulated failure of a LWMS tank, pathways, estimation of concentration and dose Technical Specifications and Emergency Operation Requirements 6

7 Hydrologic Environmental Review 2.3 Water: Hydrology, Water Use, and Water Quality 3.0 Plant Description: Plant Water Use, Water Consumption, Water Treatment 4.0 Environmental Impacts of Construction: Water-Related Impacts, Hydrologic Alterations, Water-Use Impacts. 5.0 Environmental Impacts of Station Operation: Water- Related Impacts, Hydrologic 6.0 Alterations and Plant Water Supply: Water-Use Impacts, Environmental Measurements and Monitoring Programs, Thermal Monitoring, Hydrological Monitoring, and Chemical Monitoring 9.0 Alternatives to the Proposed Action: No-Action Alternative, Energy Alternatives, Alternative Sites, Alternative Plant and Transmission Systems 7

8 Nuclear Power Generation in the United States Operation of Nuclear Power Plants Under Original Licensing Regulations (10 CFR 50) Nuclear Share of Electricity Net Generation in the U.S. Consistent growth until mid-1990s New Nuclear Power Plant Applications Under 10 CFR 52 First wave of COLA applications in By the end of 2010: Applications for 18 COLAs to operate 28 new reactors were received. All under review. 5 design certification applications are being reviewed. 4 ESPs were reviewed and issued. 8

9 Hydrologic Safety Analysis of Radioactive Liquid Effluents Human Dose ECL set by regulation Postulated accident scenario: Postulated failure of a tank located outside of the containment building and the subsequent release of its contents to the environment. Pathway to the nearest potable water source: The nearest potable water supply, located in an unrestricted area, for direct human consumption or Indirectly through animals, crops, and food processing. Technical Analysis: Adequate characterization of: subsurface and aquifers, liquid radioactive effluent release scenario, screening of the radionuclide constituents, and CSMs and plausible pathways. 9

10 Conceptual Site Models (CSMs) Regulatory Goal: providing reasonable assurance that the reactor interfaces with the hydrosphere correctly and operates safely without posing a threat to public health and safety and the environment. CSMs describe qualitatively and quantitatively how the system functions and the governing processes operate. Depending on the level of complexity involved and the amount of information desired, the dimensional representation of CSMs could be 1-D, 2-D cross sectional, 2-D planar, or 3-D. 10

11 CSM Example AUXILIARY BUILDING SOIL AND SAPROLITE PROPOSED FINAL GRADE FILL EFFLUENT HOLDING TANK IN-SITU FILL AUXILIARY HOLDING POND PARTIALLY WEATHERED ROCK BASE MAT SOIL AND SAPROLITE RIVER BEDROCK PARTIALLY WEATHERED ROCK GROUNDWATER FLOW DIRECTION Conceptual model for evaluating radionuclide transport in groundwater (modified from WSL COLA) NOT TO SCALE RADIOACTIVE LIQUID EFFLUENT RELEASED FROM RUPTURED HOLDUP TANK 11

12 CSM to Predictive Modeling START Geologic and Hydrogeologic Data Hydrologic Data Site Engineering Design Data Scenarios Source Term Potable Water Source Alternate Pathway 1 Alternate Pathway 2 Alternate Pathway n Uncertainty Analysis Conservatism Acceptable? Yes No Conceptual Site Model Mathematical Model Analytical Model Numerical Model 12

13 Water is essential to produce energy and power Thermoelectric cooling Hydropower Minerals extraction/mining Fuel Production (fossil fuels, biofuels, etc) Emission control The Energy Water Nexus Energy is essential for water utilization Storing Pumping Treating Distributing Recreational use Conjunctive use Surface and Ground water 13

14 Thermoelectric Power Generation and Water Needs Thermoelectric power generation relies heavily on availability of large quantities of freshwater resources. Approximately 89% of the energy produced in the U.S. uses thermoelectric systems (AEO, 2011) Thermoelectric power plants account for 39% of total U.S. freshwater withdrawals (GAO, 2009). Water consumption depends on cooling system type Three types of cooling system designs in use by thermoelectric plants; once-through, closed-loop (wet recirculating), and dry cooling systems. 14

15 Net Electricity Generation: Total net generation: 3,953 billion kwh Other gases 0.3% Petroleum 1.0% Natural gas 23.3% Coal 44.6% Nuclear 20.2% 2009 Non-hydro renewable net generation: 141 billion kwh Conventional hydroelectric 6.9% Other 0.3% Other renewable 3.6% Wind: 1.8% Solar thermal and photovoltaic (PV): <0.1% Wood and wood-derived fuels: 0.9% Geothermal: 0.4% Other biomass: 0.5% 70% fossil fuels, 20% nuclear, and 10% renewable Source: EIA Electric Power Monthly, October

16 Trend of Electricity Consumption percent growth (3-year rolling average) Projection projected electricity consumption grows by 30%, the rate of growth has slowed History Period Annual Growth 1950s s s s s Source: EIA, Annual Energy Outlook

17 Trends in Thermoelectric Power Water Withdrawals and Population 1980 was the year with the highest withdrawal on record 17

18 Thermoelectric Water Withdrawals in 2005 Thermoelectric Power Water Withdrawals Groundwater Withdrawals Total Freshwater Withdrawals Surface Water Withdrawals Source: USGS 18

19 Water Withdrawal and Consumption for Various Power Generation Technologies Water intensity (gal/mwhe) Plant-type Process Steam Condensing Other Use Steam Withdrawal Consumption Withdrawal Consumption Coal Mining 5 74 Slurry OL Cooling 20,000 50,000 ~300 CL Tower Fossil/ biomass/ waste CL Pond ~480 ~30** Dry 0 0 Mining and Nuclear Processing Nuclear OL Cooling 25,000 60,000 ~400 Nuclear CL Tower 500 1, Nuclear CL Pond 800 1,100 ~720 ~30** Nuclear Dry 0 0 Geothermal Steam CL Tower ~2000 ~1400 Not available Solar trough CL Tower ** Solar tower CL Tower ~750 ~750 8** Other Natural Gas Supply ~11 OL Cooling 7,500 20, Natural Gas CC CL Tower ~230 ~ ** Dry 0 0 Coal IGCC* CL Tower ~250 ~ (process water)** Hydro-electric Evaporation 4500 (ave) Mining of coal consumes 0.07 to 0.26 billion gallons per day Thermoelectric power generation withdraws 136 billion gallons per day and consumes 3.3 billion gallons per day OL = Open loop cooling, CL = Closed Loop Cooling, CC = Combined Cycle *IGCC = Integrated Gasification Combined-Cycle, includes gasification process water Other Use includes water for other cooling loads such as gas turbines, equipment washing, emission treatment, restrooms, etc. 19 **References did not specify whether values are for withdrawal or consumption. Source: GAO 2006 and EPR 2002

20 Thermoelectric Generation Water Needs Estimates (using AEO 2010 regional projections for capacity additions and retirements) Case 1 Additions and retirements are proportional to current water source and type of cooling system. Case 2 All additions use freshwater and wet recirculating cooling, while retirements are proportional to current water source and cooling system. Case 3 90% of additions use freshwater and wet recirculating cooling, and 10% of additions use saline water and once-through cooling, while retirements are proportional to current water source and cooling system. Case 4 25% of additions use dry cooling and 75% of additions use freshwater and wet recirculating cooling. Retirements are proportional to current water source and cooling system. Case 5 Additions use freshwater and wet recirculating cooling, while retirements are proportional to current water source and cooling system. 5% of existing freshwater once-through cooling capacity is retrofitted with wet recirculating cooling every five years starting in Source: Estimating Freshwater Needs to Meet Future Thermoelectric Generation Requirements September 2010 DOE/NETL 20

21 Thermoelectric Water Needs - Forecasts Withdrawal is expected to decline for cases 2 through 5. Consumption is expected to increase for all 5 cases. Withdrawal Consumption 21

22 Regional Climatic Variability and Water Demand 22

23 Total, surface-water, and ground-water withdrawals, 2000 Source: USGS 23

24 Drought 24

25 Regional Drought Frequencies, Percent of time in severe and extreme drought < 5% 5% - 9.9% 10% % 15% % 20% Source: Government Accountability Office (GAO, 2003) - National Drought Mitigation Center University of Nebraska Lincoln 25

26 Availability of Freshwater Sources Cumulative monthly precipitation potential evapotranspiration From in/yr (#counties) Source: U.S. Geological Survey USGS Circular 1323 with original data source cited as the American Water Resources Association 26

27 Extent of State Shortages Likely over the Next Decade under Average Water Conditions Regional (16) Statewide (2) None (9) Local (18) No response or uncertain (5) Source: Government Accountability Office (GAO) analysis of state water managers responses to GAO survey. GAO

28 Operating Nuclear Power Plants and Years of Operation 28

29 Projected Locations of New Nuclear Power Reactors 29

30 Energy Water Conflicts? Idaho opposed two proposed power plants because of impact on aquifer 14 South Dakota Governor called for a summit to discuss drought-induced low flows on the Missouri River and the impacts on irrigation, drinkingwater systems, and power plants Low water on Missouri River leads to high pumping energy, low efficiency, load reduction and plant shutdown Arizona rejected permitting for NPP because of impact on local aquifer 6 University of Texas researchers said power plants would have to curtail production if 20th century drought conditions recurred (Clean Air Task Force, 2004a) Source: Energy Demands on Water Resources. GAO Brownsferry NPP on Tennessee River, often high water temperature at intake (86)F close to discharge (90F) Tennessee Governor imposed moratorium in 2002 on installation of new merchant plants because of cooling constraints 30

31 Water Withdrawal Trends 31

32 Thermoelectric Power Generation Impacts on Water Resources Quantity Quality Reduced water availability for competing uses. Hydrologic alterations (diversion, discharge, ponding, etc) Water use impacts Thermal Hydrodynamic Hydrologic alterations (erosion, sedimentation, etc) Chemical Biological Radiological Ecological (wetlands, aquatic life, etc) 32

33 Nuclear Power Generation Potential Impacts on Water Resources Quantity: Reduced water availability depending on type of cooling system significant withdrawals. Hydrological: Alterations for constructing intake and discharge structures. Hydrological: Alterations for onsite and offsite water storage. Hydrological: Alterations for cooling tower and UHS construction. 33

34 Nuclear Power Generation Potential Impacts on Water Resources Ecological - Quality: Impacts on aquatic and terrestrial ecology, such as wetlands, fish, wildlife. Radiological - Quality: Accidental and normal operational releases of radioactive liquid effluents into the hydrologic system and gaseous effluents through atmospheric dispersion. Thermal - Quality: Release of thermally elevated water into the hydrologic cycle. Hydrodynamic Quality: Alterations to flow characteristics and changes in flow regime. 34

35 Radioactive Effluents All light-water-cooled reactors release small quantities of radioactive materials to the environment. Criteria for doses from liquid and gaseous effluents are for any individuals in the unrestricted area from all pathways of exposure keep dose below level that has adverse impact on human health. Doses to the population within 80 km (50 mi) radius are assessed before a plant becomes operational to meet 10 CFR 50, Appendix I. Doses to humans from accidental release through all pathways are assessed prior to operation to determine compliance with 10 CFR 20, Appendix B limits 35

36 Conclusions Increase in power demand under most scenarios considered by Annual Energy Outlook (AEO) reports. Increase in water need for thermoelectric power generation. Compared to fossil fuel based plants nuclear is widely accepted as having significantly lower greenhouse gas (GHG) emission. Climatic variability likely stress in many parts of the U.S., but mainly the south and southwest. Concentration of nuclear power generation plants in the south, southeast and northeast of the country. Thermal stresses are likely to occur during low flow season. Regional water impacts could be significantly different from the national average indicators. 36

37 Conclusions Improved designs such as passive designs and hybrid cooling will reduce the consumption of water and thermal stresses. Future need to investigate the performance of thermoelectric plants under changing climatic conditions. Regulatory tools are effective to restrict thermal pollution and dose to humans and biota, but continued monitoring is essential. Modeling and monitoring are highly effective tools in maintaining the desirable level of water quality from thermal and radionuclide stresses. Understanding pathways and implementing mitigation measures in the event of an accident 37

38 Examples of regulatory requirements 10 CFR Part 50 Appendix I Numerical Guides for Design Objectives and Limiting Conditions for Operation to Meet the Criterion "As Low as is Reasonably Achievable" for Radioactive Material in Light- Water-Cooled Nuclear Power Reactor Effluents 10 CFR 20 Appendix B Annual Limits on Intake (ALIs) and Derived Air Concentrations (DACs) of Radionuclides for Occupational Exposure; Effluent Concentrations; Concentrations for Release to Sewerage The concentration values are equivalent to the radionuclide concentrations which, if inhaled or ingested continuously over the course of a year, would produce a total effective dose equivalent of 0.05 rem (50 millirem or 0.5 millisieverts). 38

39 DISCLAIMER The views expressed in this presentation are those of the authors and do not necessarily reflect the official position of the U.S. Nuclear Regulatory Commission Thank You U.S. Nuclear Regulatory Commission Contact: Nebiyu Tiruneh: 39

40 Thank You U.S. Nuclear Regulatory Commission Contact: Nebiyu Tiruneh: 40