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Lecture 1: IntroductionNuclear Forensics and the Fuel Cycle
• Readings: § Nuclear Forensics
Analysis: Chapter 1 Introduction
• Class organization§ Outcomes§ Grading
• Introduction§ What is nuclear
forensics• Nuclear material
§ Types of material § Critical masses
• Device development• Forensic goals
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Introduction
• Course objectives§ Understand and comprehend technical aspects
of nuclear forensics§ Highlight role of radiochemistry in nuclear
forensics§ Apply technical aspects to the nuclear fuel
cycle• Course will emphasize the role of nuclear forensics
in the nuclear fuel cycle§ Evaluate available tools§ Assess applications and limitations
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Course overview• Course topics
§ Basics of radiochemistry for nuclear forensics§ Role of applications in nuclear forensics§ Chemistry and physics involved in forensics§ Principles of devices§ Sampling§ Laboratory techniques§ Application of signatures§ Signatures from the fuel cycle
• Textbooks and published literature are used a reading material§ Moody, Hutcheon, Grant: Nuclear Forensic
Plutonium is a unique element in exhibiting six different crystallographic phases at ambient pressure (it has a seventh phase under pressure). In addition, unlike most metals, plutonium contracts on melting. Transformations to different crystal structures occur readily and are accompanied by very large volume changes. By comparison, aluminum’s behavior is predictable and uneventful. It expands monotonically on heating in the solid phase, and it also expands on melting. The dashed lines show that thermal contraction on cooling the liquid (L) phase of plutonium extrapolates to that of the β-phase; the thermal contraction on cooling the ε-phase extrapolates to that of the γ-phase.
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Phase never observed, slow kinetics
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Fissile and fertile material
• Fissile material§ Material that can sustain chain reaction
• Fertile materials§ Source material that can create fissile material§ 232Th, 238U
• Enrichment of U§ Gas, electromagnetic separation
• Related to power production and reactor type§ How can these be different?
à Fast, thermal, CANDU§ 1 GWe burns about 1 ton of fissile material annually
à 200 kg of Pu producedà about 70 t of Pu annually formed in reactor worldwide
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Device development• Manhattan project to Cold War
§ Little Boy, U deviceà Total mass 4100 kgà 84 % enriched 235Uà 1 % of U fissioned, 13 kt yield
§ Fat Man, Pu deviceà 6 kg, 95 % < 239Puà Total mass 4900 kgà 20 % efficient, 21 kt yield