Interim Storage of Spent Nuclear Fuel - Woods Hole Research Center

More documents

Recommendations

Info

Chapter 2 / Current Technologies, Economics, and Status of Interim Spent Fuel Storage Indeed, programs to reduce stockpiles of excess weapons plutonium are typically focused on putting that material in a form in which it would be no more accessible and attractive for use in nuclear weapons than plutonium in spent fuel—the so-called “spent fuel standard.” 34 Typical spent fuel from a light-water reactor contains roughly 1% by weight plutonium, 3-4% intensely radioactive fission products, and the remainder uranium. For some decades after the spent fuel is discharged, the gamma radiation from a typical LWR spent fuel assembly is enough to cause a lethal dose of radiation in a relatively short time to anyone attempting to handle the fuel without shielding. Under both U.S. domestic and IAEA standards, material that generates radiation of more than 100 rem/hour at one meter is considered “self-protecting” against theft and recovery of the fissile material within it, and subject to a substantially lower level of safeguards and security than material which is not self-protecting. A PWR fuel assembly irradiated to 40 megawatt-days per kilogram of heavy metal (MWd/kgHM) would generate over 2,000 rem/hour at one meter ten years after discharge, nearly 1,000 rem/hr 30 years after discharge, and nearly 200 rem/hour 100 years after discharge. 35 This radiation barrier does not last forever, however. The radioactivity from the fission products decays rapidly for the first few years after the fuel is discharged from a reactor, and then continues to decay with a half-life of about 30 years, corresponding to the decay of Cesium-137 and Strontium-90, for more than a century. Since the radiation barrier to theft or diversion of the spent fuel and recovery of the plutonium from it thus decays with time, it is important that other barriers – such as the geologic barrier that would be created by disposing of the fuel in a geologic repository – eventually be put in place to ensure that the spent fuel continues to pose a low proliferation risk. 36 Safeguards for spent fuel storage are straightforward. The purposes and implementation of safeguards are different in the United States (which is a nuclear-weapon state) and Japan (which is a non-nuclear-weapon state). In the United States, while civilian reactor facilities are eligible for IAEA safeguards under the U.S. voluntary offer agreement, in practice the IAEA does not choose to expend its limited resources safeguarding U.S. civilian reactors. The safeguards that are applied are U.S. domestic safeguards, designed to ensure against possible theft or sabotage of the material, not international verification of peaceful use. In Japan, the Nonproliferation Treaty requires safeguards on all peaceful nuclear activities, and so both domestic and IAEA safeguards measures are applied to all spent nuclear fuel. To safeguard a spent fuel pool, the spent fuel assemblies are counted as individual items – there is no measurement uncertainty as there is when nuclear material is handled in powders or solutions. Radiation monitoring techniques or instruments to check the Cherenkov glow from highly radioactive spent fuel can be used to ensure that the spent fuel assemblies are genuine, and not substituted with dummies. Surveillance cameras are used to monitor any movement of the spent fuel. For IAEA safeguards, the timeliness goal for detecting any diversion of material in spent nuclear fuel is three months, so routine inspections are performed at Japanese spent fuel storage pools every three months, and an inventory inspection once a year. 37 Non-destructive assay is performed on any 34 This standard was first outlined in Committee on International Security and Arms Control, U.S. National Academy of Sciences, Management and Disposition of Excess Weapons Plutonium (Washington, DC: National Academy Press, 1994); for a more detailed discussion of what the spent fuel standard implies, see The Spent-Fuel Standard for Disposition of Excess Weapon Plutonium, op. cit. 35 See Committee on International Security and Arms Control, Panel on Reactor-Related Options, U.S. National Academy of Sciences, Management and Disposition of Excess Weapons Plutonium: Reactor-Related Options (Washington, DC: National Academy Press, 1995) pp. 270-273. 36 For this reason, the 1994 National Academy of Sciences study of plutonium disposition (Management and Disposition of Excess Weapons Plutonium, op. cit.) concluded, in a section entitled “Beyond the Spent Fuel Standard,” that “long-term steps will be needed to reduce the proliferation risks posed by the entire global stock of plutonium, particularly as the radiaoactivity of spent fuel decays.” The report identified geologic disposal and fission options to burn plutonium stocks much more completely as among the possibilities to be considered, and recommended that “research on fission options for near-total elimination of plutonium should continue at the conceptual level.” (p. 17) 37 See, for example, discussion in Saegusa, Ito, and Suzuki, An Overview of the State of the Arts of Nuclear Spent Fuel Management, op. cit. 17
18 spent fuel assemblies received at or shipped from the spent fuel pool. Safeguarding spent fuel in dry cask storage is both simpler and more complex than safeguarding spent fuel in wet pools. It is simpler in that once the spent fuel is loaded into the cask and the cask sealed, the fuel is inaccessible, welded or bolted into the cask until the cask is opened again (which may not happen for decades), and there are no ongoing movements of fuel that need to be verified. It is more complex, since the fuel is also inaccessible for regular inspection, making it necessary to rely on containment and surveillance—primarily tamper-resistant seals applied to the outside of the cask—to ensure that once the fuel has been verified on loading into the cask, it remains in the cask and has not been removed. Since it would not be easy to open the cask and carry out an inspection if one of the seals were to fail, the IAEA uses a dual-seal approach with dry casks in Japan. In this approach, if one seal is accidentally broken or fails, one more is always in place to ensure continuous verification that the cask has not been opened. Initial loading of the fuel into the casks and subsequent sealing of the casks is closely monitored and repeatedly checked. Inspections every 2–3 months confirm that the seals are intact. 38 The requirements for physical security for interim spent fuel storage facilities are comparatively modest, since the spent fuel poses a much less accessible and attractive target for theft than does separated plutonium in forms that could be used directly in nuclear weapons. For storage facilities at reactor sites, the spent fuel storage simply relies on the overall security for the reactor itself, designed to prevent sabotage. For away-from-reactor stores, appropriate fencing, intrusion detection, guards, and arrangements for rapid arrival of a response force if necessary are needed, as they are for any nuclear facility. 39 In Japan, unlike the United States, nuclear facilities do not have armed guards: if an armed response is required, a response force is available some minutes away. INTERIM STORAGE OF SPENT NUCLEAR FUEL It is sometimes argued that there would be a substantial nonproliferation advantage in consolidating spent fuel in a small number of locations. 40 Certainly from the point of view of both the amount of inspector travel-time for safeguards and the expenses for security, fewer locations are better than more, and as discussed in Chapter 4, there could be significant nonproliferation advantages in consolidating spent fuel at a few international sites. But as long as current reactors continue to operate, they will continue to generate spent fuel and will continue to require safeguards and security of their own, so removing a portion of the older spent fuel from those reactors to one or more centralized locations within a particular country would not make a substantial difference in either the proliferation hazard or the safeguards and security burden. Transportation Transportation of spent nuclear fuel is a complex topic, a full treatment of which is beyond the scope of this paper. Nevertheless, if interim storage is to be carried out at awayfrom-reactor sites, transportation of the spent nuclear fuel will be required; for the international storage and disposal concepts described in Chapter 4, overseas transportation would generally be needed. Hence, at least a brief discussion of transportation is necessary. During transportation, there are inevitably somewhat greater complexities, costs, and risks than there are when the fuel is simply sitting in a storage facility—and in recent years, transportation of spent fuel and other nuclear material, particularly across national boundaries, has been the subject of substantial political controversies. The issues posed by nuclear waste transportation are quite different in the United States and Japan. Transportation of spent fuel within Japan is less difficult, costly, and controversial than it is in the United States, because Japan’s nuclear facilities are located on the coasts, so that transport 38 Ibid. 39 The U.S. Nuclear Regulatory Commission requirements for security for spent fuel storage facilities can be found at 10 Code of Federal Regulations Part 73.51: Requirements For the Physical Protection of Stored Spent Nuclear Fuel and High-Level Radioactive Waste (Washington, DC: Government Printing Office, various years, available at http://www.nrc.gov/NRC/CFR/PART073/). A recent NRC description of the approach to security planned for one particular proposed spent fuel storage facility can be found in Security Evaluation Report Concerning the Private Fuel Storage Facility, op. cit. 40 See, for example, Luther J. Carter and Thomas H. Pigford, “The World’s Growing Inventory of Spent Nuclear Fuel,” Arms Control Today, January/February 1999 (available at http://www.armscontrol.org/ACT/janfeb99/carjf99.htm).
Page 1 and 2: Interim Storage of Spent Nuclear Fu
Page 3 and 4: © 2001 Harvard University and Univ
Page 5 and 6: Observations . . . . . . . . . . .
Page 8 and 9: Executive Summary The management of
Page 10 and 11: Executive Summary ix approaches (an
Page 12 and 13: Executive Summary xi ernment’s co
Page 14 and 15: Executive Summary xiii ures could b
Page 16: Executive Summary xv proposed new o
Page 19 and 20: 2 im storage does involve a cost, i
Page 21 and 22: 4 troversy over expanding on-site s
Page 24 and 25: 2. Current Technologies, Economics,
Page 26 and 27: Chapter 2 / Current Technologies, E
Page 48: Chapter 2 / Current Technologies, E
Page 51 and 52: 34 Rokkasho-mura, but it can hold o
Page 53 and 54: 36 lished a commercial reprocessing
Page 55 and 56: 38 consent to siting new plants if
Page 57 and 58: 40 nuclear fuel cycle facilities. A
Page 59 and 60: 42 falling to 32% after the acciden
Page 61 and 62: 44 tioned in other specific activit
Page 63 and 64: 46 ities (who pass the charge on to
Page 65 and 66: 48 waste. The NWPA set firm timetab
Page 67 and 68: 50 Onsite Fuel Storage Controversie
Page 69 and 70: 52 to cover the cost of geologic di
Page 71 and 72: 54 Many spent fuel storage debates
Page 73 and 74: 56 Finally, the U.S. experience dem
Page 75 and 76: 58 would be beneficial for both the
Page 77 and 78: 60 ment context, national governmen
Page 79 and 80: 62 United States and Canada, which
Page 81 and 82: 64 may have broader interests in bu
Page 83 and 84: 66 Providing an Option to Remove Ma
Page 85 and 86:
68 and populations are fiercely opp
Page 87 and 88:
70 Past and Current Proposals Conce
Page 89 and 90:
72 Palmyra Atoll, an uninhabited U.
Page 91 and 92:
74 ates, an international waste-man
Page 93 and 94:
76 an estimated temporary storage p
Page 95 and 96:
78 available from the provision of
Page 97 and 98:
80 critical of Russia’s cooperati
Page 99 and 100:
82 planned U.S. national missile de
Page 101 and 102:
84 worked hard to convince Russian
Page 104 and 105:
5. Key Issues, Tensions, and Approa
Page 106 and 107:
Chapter 5 / Key Issues, Tensions, a
Page 108 and 109:
Page 110 and 111:
Page 112 and 113:
Page 114 and 115:
Page 116 and 117:
Page 118 and 119:
Page 120 and 121:
Page 122 and 123:
Page 124 and 125:
Page 126 and 127:
Page 128 and 129:
Page 130 and 131:
Page 132 and 133:
Page 134 and 135:
6. Conclusions and Recommendations
Page 136 and 137:
Chapter 6 / Conclusions and Recomme
Page 138 and 139:
Page 140 and 141:
Page 142:
The Project on Socio-technics of Nu
show all

Interim Storage of Spent Nuclear Fuel - Woods Hole Research Center

Create successful ePaper yourself

Delete template?

Save as template?