Module B1 Study Book - the Graduate School of the Environment

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moderator, and natural uranium fuel. They have a low thermal efficiency, and low steam pressure, but efficient use of [cheaper] uranium. Also, the heavy water moderator does not need to be pressurised, so refuelling can be done on-line: overall, this makes the CANDU one of the most economic nuclear reactors. USSR reactors VVER: a form of PWR but with major differences, eg several separate cooling circuits rather than one pressure vessel. RBMK: developed from military reactors, with graphite moderator, light water coolant and 5% enriched fuel. eg Chernobyl. 2. The nuclear fuel cycle 48 Lecture: Nuclear Power
a) Mining and extraction 75,000 tonnes of ‘yellowcake’ [the result of crushing the ore and dissolving it in sulphuric acid to produce the basic uranium] are demanded annually by the nuclear power stations of the world. The environmental hazards of mining have included [less so today, after much campaigning] exposure of the workers to radiation also from radon gas, a ‘daughter product’ of uranium by natural decay, and the fact that each tonne of uranium extracted generates 1000 tones or so of ‘tailings’. These can be 20 times as radioactive as the uranium, and contain other undesirable material, so safe storage is an issue. b) Enrichment The U3O8 is converted into uranium hexafluoride [UF6 ‘hex’]. The original method [first developed for weapons-grade fuel] uses gaseous diffusion through a porous membrane, from which U-235 emerges at a faster rate than the U-238 and can thus be recovered. In the more recently developed, cheaper method, a centrifuge spins the gas at high velocity, with the heavier U-238 going to the outside, leaving the central layer richer in U-235. One tonne of enriched uranium leaves 6 tonnes of depleted uranium, which is mostly treated as waste, with some going into weapons and some going to breeder reactors. c) Spent fuel After three years in the reactor, the spent fuel [ie no longer producing enough fission to be economic] contains a range of proportions of ingredients, according to type of plant, mode of operation and degree of original enrichment of the fuel. For a PWR with 3.5% U-235, typical values per kg would be : Item * = kg x 10-3 [ie thousandths of a kilogramme] U-235 7* At about the same concentration as natural uranium U-238 940* Reduced by neutron absorption to plutonium and other actinides Plutonium 9* Less than half of the total produced from the U-238 via fission, which contributed to the power output Fission products 38* Lighter radioactive isotopes, with widely varying halflives [fractions of a second to several years]. Almost all the initial radioactivity of the spent fuel. Actinides 6* That is heavy radioactive isotopes, producing most of the radioactivity after a few hundred years. d) Disposal of spent fuel Normally, it is submerged in water, in a vessel surrounded by a radiation shield, and with a heat extraction system, for at least a year. Then it is subject to either:- i) Direct disposal: left in tanks for several decades, by which time the radioactivity and heat production will have fallen to levels allowing easier, more compact, storage. Adopted by, eg, USA and Sweden. Or:- ii) Reprocessing ie separating it into uranium, plutonium and other wastes [last two items on ‘spent fuel’ table]. World capacity for reprocessing is about 5,000 tonnes/year, mostly in UK [47%], France [40%] and Russia [8%] with Lecture: Nuclear Power 49
Page 1 and 2: Module B1 Study Book Section 1: Cor
Page 3 and 4: Section 1: Core Module Information
Page 5 and 6: A warm welcome to the new students;
Page 7 and 8: Student Feedback Analysis The follo
Page 9 and 10: work was done. The marks allocated
Page 11 and 12: 5. Is any unfairness justified by t
Page 13 and 14: Lecture: Energy Futures Paul Allen
Page 15 and 16: are not developed fast enough There
Page 17 and 18: with some coal in Europe, Asia, and
Page 19 and 20: tell exactly which day we will get
Page 21 and 22: We must integrate our science and p
Page 23 and 24: Features Consequences Impacts Table
Page 25 and 26: disposal (recycling, landfill, inci
Page 27 and 28: 9. Community 10. Business A series
Page 29 and 30: Background The Building Research Es
Page 31 and 32: Weighting of Environmental Issues 3
Page 33 and 34: 10 visual comfort 11 olfactory comf
Page 35 and 36: ESI-3: Net annual consumption of pr
Page 37 and 38: EcoHomes. 3.9.3 PROPOSED FUTURE REQ
Page 39 and 40: • The removal of two location spe
Page 41 and 42: Environmental impact of materials R
Page 43 and 44: 8. Sustainable construction - waste
Page 45 and 46: Lecture: Nuclear power Damian Randl
Page 47 and 48: ) Fission reactors: the basics For
Page 49: The core of a PWR, an open lattice
Page 53 and 54: further use. Optimists have suggest
Page 55 and 56: ) The economics of nuclear have bee
Page 57 and 58: wastes deep underground in Britain
Page 59 and 60: A bigger step is proposed by the Hi
Page 61 and 62: The evidence of the British Nuclear
Page 63 and 64: energy efficient as a nation and de
Page 65 and 66: 5. Is any unfairness justified by t
Page 67 and 68: elates to the gradual reduction of
Page 69 and 70: The total of 335 million tonnes in
Page 71 and 72: of the waste management industry. T
Page 73 and 74: the targets, where the baseline is
Page 75 and 76: criteria for the collection, treatm
Page 77 and 78: system will strive to exploit the u
Page 79 and 80: This building, the workplace of som
Page 81 and 82: Energy Consumption Figures: • Act
Page 83 and 84: Main aspects of the project include
Page 85 and 86: (i.e. proportions of windows and op
Page 87 and 88: • Reduction in heat gains from li
Page 89 and 90: transmission lines. It was complete
Page 91 and 92: Distribution The Area Boards in Eng
Page 93 and 94: generation of electricity rose by 8
Page 95 and 96: electricity demand. The Grid and re
Page 97 and 98: Source: IEA report • "The maximum
Page 99 and 100: Time and power rating of various el
Page 101 and 102:
Reducing output from a source that
Page 103 and 104:
In practice: • now around 5% of t
Page 105 and 106:
enewables. In the UK, Ofgem has app
Page 107 and 108:
a) System regulatory barriers: what
Page 109 and 110:
customers of existing electricity s
Page 111 and 112:
http://www.sussex.ac.uk/sussexenerg
Page 113 and 114:
issues of ‘sustainable’ develop
Page 115 and 116:
Towards the Planning White Paper 20
Page 117 and 118:
There is feeling amongst some archi
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eight weeks, but can often take muc
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eaching implications to both budget
Page 123 and 124:
white goods (fridges, washing machi
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and Resources Action Programme (WRA
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Edwards, S (2003) Principle Consult
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Lecture: Getting Something Built Pa
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trade contractor to start and futur
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Section 3: Relevant Papers Waste Mi
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industry has placed waste reduction
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The trend in the design constructio
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minimising environmental impact (in
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ordination. Building Services Journ
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this threat that is real and yet in
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obliged now to begin planning for t
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and plant species ― from bacteria
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oil and natural gas, and some coal)
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challenging to determine what the h
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Just as it is morally obligatory to
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The cultures and religious traditio
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since they will depend upon their n
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20 Michael McCarthy, The Independen
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Heinberg, Richard. Powerdown: Optio
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2003 Green Building Costs and Finan
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How much more do green buildings co
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The Report calculates these additio
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A 1% increase in productivity (equa
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Figure 3 Financial Benefits of Gree
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Paper: Advanced Interactive Facades
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engaging an industry consortium in
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3. STATE-OF-THE-ART IN EUROPE AND U
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analyzed under a range of diverse c
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4.4 Innovation will improve hardwar
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The environmental rationale appears
Page 185 and 186:
Student Essay: Ishaq Muhammad Unit:
Page 187 and 188:
Source: MidTherm Limited-www.midthe
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Analysis The Dining Hall has slopin
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equired. Night-time cooling: Yes Oc
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temperature within the educational
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(Sullivan, 2006). This means the in
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Great Britain. DfES. (2006). Buildi
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• to pump the water through the p
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and energy efficiency. So people bu
Page 203 and 204:
Apart from energy labelling, there
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what is worse, it is possible to re
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Tacoma Power, Tacoma Public Utiliti
Page 209 and 210:
Air Blowers: Some spas are equipped
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Module B1 Study Book - the Graduate School of the Environment

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