Chapter 7. Nuclear Waste

1. Chapter 7. Nuclear Waste • Nuclear Waste Disposal: Amounts of Waste Categories of Nuclear Waste Wastes from Commercial Reactors Hazard Measures for Nuclear Wastes 2. Storage and Disposal of Nuclear Wastes Stages in Waste Handling Deep Geologic Disposal Alternatives to Deep Geologic Disposal Worldwide Status of Nuclear Waste Disposal Plans

2. 1.1 Categories of Nuclear Waste The Nature of the Problem Military and Civilian Wastes Wastes from commercial nuclear reactors raise more critical issues the amounts are greater, their production continues… Form Half lifetime Radioactivity level As with all radioactive sources, radioactive waste is potentially hazardous to health. Therefore, it must be managed in a safe way to protect people and the environment 城市放射性废物管理办法 IAEA Safety Standards: Geological disposal of radioactive waste

3. Good waste management begins before the waste is generated: the starting point for all activities that produce radioactive waste is to avoid or reduce waste generation at its source. Minimizing primary waste generation also minimizes the quantity of waste requiring disposal.

4. Bad News: Wastes from commercial nuclear reactors raise more critical issues the amounts are greater, their production continues… Good News: The world has over half a century’s knowledge and experience on how to deal with nuclear waste. When the characteristics of the waste are known, it can be managed. -IAEA

5. Types of Waste • High-level waste (HLW) • Transuranic waste (TRU) • Low-level waste (LLW) • Uranium Mill Tailings This categorization varies slightly from country to country, but in principle the main criteria for determining the type of waste are derived from radioactive content and half-life, i.e. the time taken for the waste to lose half of its radioactivity.

6. Types of Waste • High-Level Waste • The most dangerous radioactive waste • Spent fuel comes from nuclear reactors (52,000 tons) • liquid and solid waste from plutonium production (91 million gallons). • About 70 percent of the available storage space is now filled with used fuel assemblies at Turkey Point.

7. Types of Waste Transuranic Waste • Includes clothing, tools, and other materials contaminated with plutonium, neptunium, and other man-made elements heavier than uranium.

8. Types of Waste • Low and Mixed Low-Level Waste • Includes radioactive and hazardous wastes from hospitals, research institutions, and decommissioned power plants (472 million cubic feet)

9. Types of Waste • Uranium Mill Tailings • Residues left from the extraction of uranium ore (265 million tons)).

10. Mining • Uranium ore is usually located aerially; core samples are then drilled and analyzed by geologists. The uranium ore is extracted by means of drilling and blasting. Mines can be in either open pits or underground. Uranium concentrations are a small percentage of the rock that is mined, so tons of tailings waste are generated by the mining process.

11. Production in 2000 Source: http://www.world-nuclear.org/search/index.htm

13. Whatever the type of the radioactive waste, all of it has to be disposed of in a safe manner! It is a common misbelief that radioactive waste takes up a lot of space. However, all the spent fuel generated by two 860 MW reactors during their 40 years of operation would fit into three 10 metre by ten metre pools.

14. Measures of Waste Magnitudes Mass: The most common mass measure for nuclear waste is the mass of the uranium in the initial fuel, more broadly designated as metric tonnes of initial heavy metal (MTIHM or MTHM) Volume: The volume of the fuel can be inferred from the UO2 mass and density (about 10 tonnes/m3). Radioactivity: in terms of the activity (in curies or becquerels) taken either for the radionuclides individually or for their sum. radionuclides differ in the types of particles emitted, their energy, the half-lives, and the possibility of their reaching the biosphere. Nonetheless, it provides some overall perspective. Heat output: on the scale of 6 kW of heat are produced per megacurie of activity

15. 1.2 Wastes from Commercial Reactors Mass and Volume per GWyr

16. Activity of selected radionuclides in spent fuel versus time since discharge of fuel from reactor

17. Activity of selected radionuclides as a function of time

18. Heat Production The handling of the nuclear wastes is significantly complicated by the heat generated in the decay of the radionuclides The heat generation per unit activity depends on the energy carried by the emitted particles. 1 megacurie → 5.93 kW (at 1 MeV per disintegration).

19. Decay of spent fuel from 1 GWyr of PWR operation, for burnup of 40 GWd/t (28.5 MTHM): activity and thermal output as a function of time since discharge.

20. 1.3 Hazard Measures for Nuclear Wastes Total System Performance Assessments (TSPAs) The maximum permissible concentration is established as the maximum level acceptable for drinking water is closely related to the annual limit on intake (ALI). 20 mSv/yr The water dilution volume (in cubic meters) is the amount of water required to dilute the radionuclide to the maximum permissible concentration.

21. Illustration of use of water dilution volume: WDV of radionuclides in PWR spent fuel, as a function of time

22. Chapter 7. Nuclear Waste • Nuclear Waste Disposal: Amounts of Waste Categories of Nuclear Waste Wastes from Commercial Reactors Hazard Measures for Nuclear Wastes 2. Storage and Disposal of Nuclear Wastes Stages in Waste Handling Deep Geologic Disposal Alternatives to Deep Geologic Disposal Worldwide Status of Nuclear Waste Disposal Plans

23. Waste Storage Alternatives • Leave It Where It Is • Deep Geologic Disposal • Yucca Mountain, Nevada • Salt Cave Disposal • WIPP near Carlsbad, New Mexico • Very Deep Holes (6 miles) • Ice-Sheet Disposal • Space Disposal • Sub-Seabed Disposal • Island Geologic Disposal • Deep-Well Injection Disposal • Vitrification (Glass Waste) • Reprocessing It is better to have used nuclear fuel in one location

24. NIMBY: Not In My Back Yard • Fear of radiation because they don’t understand it • Concern that the waste facility willrelease long-term contamination • Worry that property values will be reducedwith construction of a waste facility • Belief that power companies are the ones responsible for storing their own waste • People don’t want dumped on by otherpeoples’ waste • Belief that nuclear power should just goaway and be replaced by other energyresources • Environmental concerns

25. Current Waste Disposal • At this time, radioactive wastes are being stored at the Department of Energy’s facilities around the country • High level wastes are stored in underground carbon or stainless steel tanks • Spent nuclear fuel is put in above-ground dry storage facilities and in water-filled pools

26. Current High-Level Waste Storage in the US

27. www.nei.org

28. 2.2 Deep Geologic Disposal In every option, deep geological disposal is the preferred final end point. The principle of geological disposal is to isolate the waste deep inside a suitable host formation, e.g. granite（花岗岩）, salt or clay. The waste is placed in an underground facility or disposal facility, designed to ensure that a system of natural and multiple artificial barriers work together to prevent radioactivity from escaping.

29. Yucca Mountain The Future of Nuclear Waste Storage

30. Yucca Mountain Project: Nuclear Fuel and High Level Waste Repository • Much more secure repository than leaving high level waste at 60 reactor sites around the country. • On old atomic bomb testing base, inside a mountain. • The storage is above the water table. • The Yucca Mountain site would be 60% filled by present waste. • US has legal commitment to the reactor industry. • Site has been studied extensively by scientists for over 20 years. • Will store waste during its 10,000 year decay time. • Questions of how to deflect dripping water around and under the storage vessels. • Questions of radioactive decay weakening storage containers. • A solution would be to build containers that can be opened and reincased, or to which surrounded casings could be added.

32. Transportation Concerns

33. Artist’s conception of transportation cask and carrier for truck transport; total length = 18 m (56 ft).

35. Typical Low-Level Waste Disposal Site Hanford (Nuclear News, November 2004)

36. 2.4 Worldwide Status of Nuclear Waste Disposal Plans

39. 高放废物地质处置研究开发规划指南 国 防 科 学 技 术 工 业 委 员 会 科 学 技 术 部 国 家 环 境 保 护 总 局 2006 我国高放废物地质处置规划研究的总体思路是： 统筹规划、协调发展、分步决策、循序渐进。

40. 研究开发和处置库工程建设包括三个阶段： 试验室研究开发和处置库选址阶段（2006－2020）、 地下试验阶段（2021－2040）、 原型处置库验证与处置库建设阶段（2041－本世纪中叶） 甘肃北山3个预选地段（旧井、野马泉、向阳山-新场） 北山完整的花岗岩体

41. 高放废物地质处置的主要内容框架 安全评价 安全标准 数据库 程 序 景象开发 后果分析 不确定分析 核素迁移特征 工程设计 开挖技术 硐室稳定性 工程布局、间隔 膨润土、废物罐 工程经济…. 场址特征 地质稳定性、地震安全性 水文地质、地球化学 工程地质、岩石、裂隙 深部地质环境 未来变化 地学信息库….. 岩石力学 工程屏障 膨润土 废物罐

42. 高放废物地质处置：科学挑战 • 处置库中的废物： • 放射性强 • 毒性大 • 半衰期长 • 处置库的安全评价期至少要达到1万年。 • 这一要求是前任何工程所没有的。 • 并且要求有科学、可信的手段评价处置库是 • 安全的 核工业北京地质研究院，Beijing Research Institute of Uranium Geology

43. In terms of good practices of radioactive waste management, responsibility covers all the steps from ‘cradle to grave’.

44. Living is not a risk-free endeavour to be sure.

45. Chapter 7. Nuclear Waste • Nuclear Waste Disposal: Amounts of Waste Categories of Nuclear Waste Wastes from Commercial Reactors Hazard Measures for Nuclear Wastes 2. Storage and Disposal of Nuclear Wastes Stages in Waste Handling Deep Geologic Disposal Alternatives to Deep Geologic Disposal Worldwide Status of Nuclear Waste Disposal Plans

46. 王 驹, Oriel Wilson, Raquel R. Pinderhughes, Dennis Silverman, Lindsey Garst Jay Nargundkar, Jonah Richmond