Nuclear Technology Review 2011 - IAEA

More documents

Recommendations

Info

FIG. III-2. Field work at a coastal aquifer in Peru. a horizontal or lateral gradient (age increasing with distance from area of recharge). In the former case this gradient is approximately proportional to the inverse of the recharge rate (volume/time), while in the latter case the gradient is approximately proportional to the inverse of the flow velocity. Therefore, the hydrogeologically relevant parameters primarily addressed by groundwater dating with radioactive isotopes are the recharge rate and flow velocity of groundwater in unconfined and confined aquifers, respectively. One of the approaches to determine groundwater flow rate is to estimate flow velocity by measuring the decrease in the radioisotope concentration along the flow path. If the mean porosity value of the aquifer is known, groundwater flow rate can be estimated. This simple approach requires access to at least two wells along the flow path of an aquifer and knowledge of the initial radioisotope concentration in the recharge area (Fig. III-2). Under natural conditions, groundwater movement is generally very slow, often in the order of a few metres per year. Water that has moved a few kilometres 81
along the flow path under these conditions is hundreds or thousands of years old; an age beyond the dating range of tritium, tritium and helium-3, and chlorofluorocarbons. Therefore, in large aquifers with long flow paths, the most common radiometric approach to determining groundwater residence times has been carbon-14. Its half-life of 5730 years makes it a suitable tool for the dating of groundwater in an age range of about 2000 to 40 000 years. Very slow moving groundwater in deep confined aquifers extending over tens and, in some cases, several hundreds of kilometres can reach ages of tens and even hundreds of thousands of years. These ages are beyond the dating range of carbon-14 and require the use of very long-lived radioisotopes. Of the three longlived radioisotopes used in water studies — krypton-81, chlorine-36 and iodine- 129 — only chlorine-36 has been found to have wider practical use so far. However, interpretation of chlorine-36 data to ascertain groundwater age is often hampered by insufficient knowledge of in situ production of the isotope owing to reactions in the aquifer matrix. Recent developments in sampling and analytical methods suggest that the use of krypton-81 may grow substantially given that it is a reliable tool to date groundwater in the range of 40 000 to 1 million years old. III–2.3. Interconnections between aquifers Both groundwater dynamics and groundwater contamination can be influenced by hydraulic interconnections between aquifers. Environmental isotopes, especially stable isotopes, can be used to investigate such interconnections, provided the isotopic composition of groundwater in the aquifers being measured is different. Thus, isotopes can be used to prove a lack of hydraulic interconnections between aquifers based on contrasting compositions. In some settings, hydraulic connections exist naturally between aquifers, and this can be evaluated through variations in isotopic composition. Intense exploitation of an aquifer can induce leakage from overlying and underlying aquifers. Stable isotope data can be used to estimate the flow of groundwater from adjacent aquifers. III–2.4. Interaction between surface water and groundwater Groundwater often consists of a mixture of recharge from surface water (lakes or rivers) and local precipitation. It is important to know the proportions of these recharge components in order to increase the sustainable supply of drinking water through bank infiltration, and to prevent drinking water pollution by infiltration of water from a contaminated surface water source. Different recharge components can be identified through the stable isotope compositions of groundwater because evaporation of water in surface water bodies, in particular 82
Page 2 and 3:
NUCLEAR TECHNOLOGY REVIEW 2011
Page 4 and 5:
NUCLEAR TECHNOLOGY REVIEW 2011 INTE
Page 6 and 7:
CONTENTS EXECUTIVE SUMMARY. . . . .
Page 8:
ANNEX II: ENHANCING FOOD SAFETY AND
Page 11 and 12:
when, where and how they will build
Page 13 and 14:
esearchers to date and study such l
Page 15 and 16:
TABLE A-1. NUCLEAR POWER REACTORS I
Page 17 and 18:
In some European countries, where r
Page 19 and 20:
esults in increased electricity dem
Page 21 and 22:
2008, an increase of 133% on the 20
Page 23 and 24:
Corporation (Rosatom) and placed un
Page 25 and 26:
induction melter at the R7 plant in
Page 27 and 28:
dismantling and removal of all inte
Page 29 and 30:
B.1. Advanced fission 6 20 B. ADVAN
Page 31 and 32:
Generation IV International Forum
Page 33 and 34:
sustainable nuclear energy systems,
Page 35 and 36:
26 C. ATOMIC AND NUCLEAR DATA The m
Page 37 and 38:
28 FIG. C-3. LCLS X ray free electr
Page 39 and 40: Restoration Centre of the Museums o
Page 41 and 42: facilities, from HEU to LEU. In 200
Page 43 and 44: 34 E. NUCLEAR TECHNOLOGIES IN FOOD
Page 45 and 46: FIG. E-1. Parasitoid females probin
Page 47 and 48: 38 Applying existing tools to chara
Page 49 and 50: spatial and temporal scales and, he
Page 51 and 52: F.1. Nutrition 42 F. HUMAN HEALTH S
Page 53 and 54: The scanning time is reduced to a f
Page 55 and 56: The demand from Member States for t
Page 57 and 58: 48 H. WATER RESOURCES 20 Studies us
Page 59 and 60: I.1.2. Security of supplies of moly
Page 61 and 62: FIG. I-2. Sketch of GPS integrated
Page 64 and 65: Annex I RECENT DEVELOPMENTS IN THE
Page 66 and 67: Safety margins are used in order to
Page 68 and 69: Fig. I-2. A linear accelerator comm
Page 70 and 71: movements and triggers the treatmen
Page 72 and 73: I-3.4. Introduction of advanced tec
Page 74 and 75: isotope with a half-life of 5.27 ye
Page 76 and 77: [I-11] BRADA, M., PIJLS-JOHANNESMA,
Page 78 and 79: necessary. Such action can reduce t
Page 80 and 81: elated to carbon dioxide uptake and
Page 82 and 83: infancy. The development and applic
Page 84 and 85: The limitations inherent in analyti
Page 86 and 87: [II-19] RHODES, et al., Emerging Te
Page 88 and 89: If most of the recharge is derived
Page 92 and 93: under semi-arid and arid conditions
Page 94 and 95: FIG. III-3. Map of the Guaraní Aqu
Page 96 and 97: colours) compared to the west side
Page 98 and 99: FIG. III-6. Map showing the locatio
Page 100 and 101: FIG. III-7. Oblique views of the ge
Page 102: Atoms for Peace Atoms for Peace
show all

Nuclear Technology Review 2011 - IAEA

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?