TENR - Technologically Enhanced Natural Radiation (eBook)

Anselmo Salles Paschoa, F. Steinhausler (Autoren)

eBook Download: EPUB

2009 | 1. Auflage
244 Seiten
Elsevier Science (Verlag)
978-0-08-091418-3 (ISBN)

Infos

This book on TENR discusses the basic Physics and Chemistry principles of natural radiation. The current knowledge of the biological effects of natural radiation is summarized. A wide variety of topics, from cosmic radiation to atmospheric, terrestrial and aquatic radiation is addressed, including radon, thoron, and depleted uranium. Issues like terrorism and geochronology using natural radiation are also examined.

• Comprehensive global TENR data assembly
• Critical assessment of the significant radiological impact of TENR on man and the environment as compared to radiological impact from man-made sources in nuclear technology and nuclear medicine
• Illustration of the importance of TENR for the future conceptual development of radiation protection

Inhalt

Front Cover 1
Technologically Enhanced Natural Radiation 4
Copyright Page 5
Contents 6
Preface 8
Chapter 1. Introduction 12
1.1. Is TENR a Universal Issue? 12
1.2. TENR – A Global Issue 15
1.3. Overview 20
Chapter 2. Depleted Uranium (DU) as TENR 30
2.1. A Brief History of DU 30
2.2. DU Inventories 33
2.3. DU as TENR and its Impacts 37
Chapter 3. Terrestrial, Atmospheric, and Aquatic Natural Radioactivity 40
3.1. Terrestrial and Atmospheric Natural Radioactivity 40
3.2. TENR Industries 57
Chapter 4. Cosmic Radiation, Including its Effects on Airline Crew, Frequent Flyers, and Space Travel 98
4.1. The Issue 98
4.2. Source Term: Cosmic Radiation 98
4.3. Doses Due to Cosmic Radiation 113
4.4. Effects of Cosmic Radiation on Avionics 130
Chapter 5. Metrology and Modeling 134
5.1. Metrology 134
5.2. Modeling 147
Chapter 6. Legal Aspects of Natural Radiation 152
6.1. Protection against TENORM Exposures 152
6.2. Heterogeneous International Approach 153
6.3. Regulatory Framework for NORM Industries 154
Chapter 7. Terrorism and Natural Radiation 164
7.1. Natural Radionuclides as a Terrorist Weapon 164
7.2. Suitable Natural Radionuclides 165
7.3. Illegal Acquisition of Natural Radioactive Material 167
7.4. Motivation for a Terrorist Attack with Natural Radionuclides 168
7.5. Modes of Attack with Natural Radionuclides 169
7.6. Risk Assessment 176
7.7. Societal Response 178
Overview 182
References 186
Author Index 220
A 220
B 220
C 221
D 221
E 222
F 222
G 222
H 222
I 223
J 223
K 223
L 224
M 224
N 225
O 225
P 225
Q 226
R 226
S 226
T 227
U 227
V 228
W 228
Y 228
Z 228
Subject Index 230
A 230
B 231
C 231
D 232
E 234
F 235
G 235
H 236
I 236
J 237
K 237
L 237
M 237
N 238
O 239
P 239
Q 240
R 240
S 242
T 244
U 244
V 245
W 245
X 245
Z 245

Textauszug

Chapter 2

Depleted Uranium (DU) as TENR

A.S. Paschoa; F. Steinhäusler

Publisher Summary

This chapter discusses depleted uranium (DU) as technologically enhanced natural radiation (TENR) and its impacts. It is well known that there are insoluble uranium oxide particles in uranium mines and in facilities that process nuclear fuels. However, the pyrophoric behavior of metallic uranium particles may produce small hot dust particles, which if inhaled may incur internal localized alpha radiation doses in addition to the uranium chemical toxicity. When DU is used as shielding in casks for a number of materials, including spent fuel or high-level waste, there is scant possibility of forming hot dust particles. However, DU is used to pierce armor plating in cruise missiles and in the armor of tanks, which may lead to the pyrophoric behavior of metallic uranium in the event of battle. In such cases, DU may become a toxic as well as a radiological problem. Some reports indicate that in DU used for military purposes, there are trace contaminants at the parts per billion levels of neptunium, plutonium, americium, technetium-99, and uranium-236.

2.1 A BRIEF HISTORY OF DU

Natural uranium (NU) is composed approximately of 99.27% 238U, 0.72% 235U, and 0.0055% 234U. A by-product of the production of low enriched uranium (LEU) and highly enriched uranium (HEU) – that is, uranium enriched in 235U to low or high percentages – used for fission in nuclear reactors and nuclear weapons, respectively, is called depleted uranium (DU). Once the 235U-enriched fraction obtained in the enrichment process is removed, the typical DU remnants comprise 99.8% 238U, 0.2% 235U, and 0.001% 234U. This means that DU contains less than a third of the 235U than NU. During the Manhattan Project, the term “depletalloy” was used to refer to an alloy in which the fissile 235U had been reduced (Raabe, 2002). In fact, the term depletalloy was derived from other terms used in the Manhattan Project like tuballoy (NU) and oralloy (enriched uranium). Other code names like Q-metal and D-38 were also used in the past. Stocks of DU are usually found as UF6, U3O8, or metal. Here, it is worth mentioning that, on August 19, 1943, in Quebec Citadel overlooking the Plains of Abraham, Franklyn Delano Roosevelt and Winston Churchill signed the “Articles of Agreement Governing collaboration between the authorities of the U.S.A. and the U.K. in the matter of Tube Alloys” which became better known as the Quebec Agreement that first formalized the nuclear agreement between these two countries during World War II (WWII) (Hewlett and Anderson, 1962). In the context of the Quebec Agreement, the expression “Tube Alloys” was the code name for the British uranium program. At the end of WWII, there were attempts to use metallic uranium in armor-piercing ammunition (Gaca et al., 2005).

The density of metallic DU is 19.0 g cm−3. This high density makes DU appropriate for use in several types of ammunition. DU is used, for example, to pierce armor plating, in cruise missiles, and in the armor of tanks. In 1968, a patent requirement was filed by Brevets, Aero-Mecaniques S.A. (Geneva, CH), for a long-burning pyrotechnic material containing DU for spotting rifle projectiles (US Patent, 1971).

DU-bearing projectiles started being widely used in the Desert Storm War (i.e., Gulf War, 1990–1991). Later the “Gulf War Syndrome” called the public and governmental attention to the potential consequences of using DU in ammunition (Department of Veterans Affairs, 1995; Eisenbud and Gesell, 1997). DU has been used in antitank weaponry, and in tank shielding against regular weaponry.

As a matter of fact, the use of DU by the military in the Gulf War, and in the conflict in the Balkans, has caused considerable concern amongst the general public. NATO Member States reported the incidence of health effects and led to speculation on their potential link to an increased exposure by soldiers to DU in the line of duty (Steinhäusler and Paschoa, 2005). Moreover, claims have been made about the possible threat to the health of residents in DU-affected areas. The United Nations Environment Programme (UNEP) sponsored a DU postconflict environmental assessment in Kosovo, Serbia, and Montenegro (UNEP, 2001, UNEP, 2002).

During the first surveys made by UNEP in Kosovo, only a NaI(Tl) detector with an alarm signal capable of being heard above the traffic noise and the wind could be used (UNEP, 2002). The UNEP surveys were carried out to locate potential DU-contaminated sites. Ge(Li) detectors could not be used at the time because it was not possible to transport the liquid nitrogen that was essential to cool them before applying bias voltage. However, after the publication of the surveys in Kosovo, the Yugoslavian authorities invited a UNEP team to carry out DU studies in Serbia and Montenegro (UNEP, 2002). This time a large number of soil samples were collected to be measured subsequently. The NU levels of the soils at the sites of collection ranged from 1.0 to 9.5 mg U kg−1 soil (UNEP, 2002). Taking into account the 0.7% 235U abundance in NU, DU was defined by the UNEP team as having 235U abundance in soil samples equal to or less than 0.35% (UNEP, 2002). From the soil samples collected in Serbia and Montenegro, it was determined that approximately 42% of these samples presented more than 10% DU. Here, one must bear in mind that farmers working in DU-contaminated soils, as well as children playing in such soils, might sometimes ingest small amounts of DU (IAEA, 2003a, IAEA, 2003b; McLaughlin, 2005; Bikit et al., 2005).

Nowadays, one should be well prepared to evaluate the potential health and environmental impacts associated with the possibility of future military use of DU. As a matter of fact, the issue of DU recently led several investigators to review gamma-spectrometric techniques to discriminate between NU extant in the environment and DU in contaminated areas (Bikit et al., 2001; UNEP, 2002; IAEA, 2003a, IAEA, 2003b; McLaughlin, 2005; Bikit et al., 2005).

Advantage has been taken at the beginning of the 21st century of low energy gamma-counting systems, put together originally for NORM and TENORM measurements, to develop simple gamma-spectrometric methods to measure DU (Paschoa, 2001; Paschoa et al., 2003; Bikit et al., 2005).

In the 1970s, when the use of lithium-drifted germanium detector [Ge(Li)] was still a novelty, few investigators attempted to measure 238U through the 63.3 keV transition line from daughter 234Th. This was so until the isotopic ratios 235U/238U (reported originally as 238U/235U) were successfully determined by gamma spectrometry in soils with NU content, and contaminated with DU, and then compared with the isotopic ratios obtained by mass spectrometry (Coles et al., 1974). Soils with NU content were obtained at the Livermore California Valley and at Yosemite National Park, while those soils with DU contamination were collected at a high explosive test area (Coles et al., 1974). Table 2.1 summarizes the 235U/238U isotopic ratios in natural and contaminated soils estimated from the published data (Coles et al., 1974; Paschoa et al., 2003).

Table 2.1

Isotopic ratio (235U/238U) in soils with NU and contaminated with DU as measured by gamma and mass spectrometries.

0.027±0.017

0.045±0.001

0.036±0.016

0.047±0.001

0.050±0.024

0.046±0.001

0.032±0.014

0.046±0.001

High uranium level with “natural” isotopic ratio

0.045±0.003

0.046±0.001

0.012±0.001

0.012±0.001

0.012±0.001

0.013±0.001

0.014±0.002

0.014±0.001

0.015±0.003

0.016±0.001

0.013±0.002

0.016±0.001

0.013±0.001

0.013±0.001

Source: Adapted from Coles et al. (1974) and Paschoa et al. (2003).

The soil characterized in Table 2.1 as having a low uranium level had approximately 2 ppm, and the 238U content was inferred from the 226Ra plus daughters and from the 63.3 keV gamma-ray line. By doing so, the gamma-counting statistical errors were large, as reflected in the uranium isotopic ratio, which is a function of the uranium content of the soil. This can be seen by observing in Table 2.1 the results obtained by gamma spectrometry for low and high uranium levels with the “natural” isotopic ratio. In addition, in the samples measured, 238U was not in equilibrium with its long-lived daughters 234Th and 226Ra. As a consequence, the only 226Ra-based U ratio measured, considered to be “natural,” was that of the soil with high uranium content, that is, 0.045. This isotopic ratio is consistent with the results obtained by...

Produkt-Details

• Erscheint lt. Verlag: 31.12.2009
• Sprache: englisch
• Themenwelt: Studium ► Querschnittsbereiche ► Prävention / Gesundheitsförderung
• Themenwelt: Naturwissenschaften ► Biologie ► Ökologie / Naturschutz
• Themenwelt: Naturwissenschaften ► Chemie ► Technische Chemie
• Themenwelt: Naturwissenschaften ► Physik / Astronomie ► Atom- / Kern- / Molekularphysik
• Themenwelt: Technik ► Umwelttechnik / Biotechnologie
• Themenwelt: Wirtschaft
• ISBN-10: 0-08-091418-7 / 0080914187
• ISBN-13: 978-0-08-091418-3 / 9780080914183