Appendix XI is the book's conceptual on-ramp. It is written for readers who followed the main argument but want the basic vocabulary locked down. It does not need any mathematics, but it is precise, so the later chapters can be read without taking anything on faith.
The appendix starts with the atom and its nucleus. It explains protons, neutrons and electrons, and how the number of protons sets the element and its place in the periodic table. It then covers isotopes and how they are named (U-235, Pu-239). Next comes stability: why most of the more than 3,300 known nuclides are radioactive and only about 250 are stable, and what the strong nuclear force does. It explains binding energy as the source of nuclear energy, and why U-235 and U-238, which differ by three neutrons, behave so differently in a reactor.
A compact reference, Isotopes in the Primer, groups the isotopes the main text uses most often by role:
- fissile: U-235, Pu-239 and U-233;
- fertile: U-238 and Th-232;
- key fuel-cycle and waste isotopes: Cs-137, Sr-90, I-131, Am-241, Tc-99m and U-232.
It is meant as a place to come back to when a symbol in the text is unfamiliar.
How it supports the book: the main text assumes this vocabulary from Chapter 1 (Nuclear Energy) onward. It is used most directly in Chapter 2 (Uranium), Chapter 3 (Beyond Uranium), Chapter 6 (Enrichment), Chapter 8 (Reactor Physics), Chapter 13 (Spent Nuclear Fuel) and Chapter 18 (Isotopes). Definitions for the wider vocabulary, such as fissile, fertile, criticality and decay heat, are collected in the glossary.
