PRINCIPLES OF NUCLEAR POWER INTRODUCTION TO NAVAL ENGINEERING

BASIC SYMBOLS AND NOTATIONS P e-e- X A Z where: X is the chemical symbol A is the # of protons plus neutrons Z is the # of protons only Bohr’s Model U EXAMPLE

ISOTOPES P e-e- N e-e- PN e-e- PN HYDROGENDEUTERIUM TRITIUM

BASIC FISSION EQUATION

ENERGY RELEASED 235 U+ 1 n 94 Zr Ce+ 2 1 n 92 MASS OF REACTANTS U amu n amu TOT: MASS OF PRODUCTS Zr amu Ce amu 2 n - 2( ) amu TOT: amu mass defect: = amu 1 amu = MeV where 1 Mev = 1.52x10-15 Btu Therefore: Binding Energy = MeV

TYPES OF NEUTRONS l Fast neutrons –Have KE of.1 MeV –Produced through fission –Very few will cause fission l Slow neutrons –Have KE of 1 eV –Must be slowed by a MODERATOR –Main producer of fission

THE NEUTRON LIFE CYCLE

TERMS RELATED TO REACTIVITY l REACTIVITY- –Critical –Sub-Critical –Super-Critical

UNITED STATES NAVAL REACTORS ARE PRESSURIZED WATER REACTORS

REACTOR CORE & PRESSURE VESSEL

NAVAL REACTOR SAFETY l INHERENT STABILITY l WATER IS BOTH MODERATOR AND COOLANT –POWER GOES UP –TEMP GOES UP –DENSITY GOES DOWN –# THERMALIZED NEUTRONS GOES DOWN –POWER GOES DOWN

PRESSURIZER

RADIATION & SHIELDING l Must protect personnel from the various types of radiation –Alpha particles ( very large, positive) –Beta particles (tiny, negative) –Gamma rays (no mass, no charge) –Neutrons (large, no charge)

SHIELDING

ADVANTAGES OF NUCLEAR POWER Allows for truly submersible weapons platform CVN’s can carry twice the JPF and weapons as a conventional CV Extreme endurance (only limited by food) ALL AHEAD FLANK FOR A YEAR

DISADVANTAGES OF NUCLEAR POWER l Considerable cost of construction/ decommission l Great weight of shielding materials l Environmental concerns –Public Information

FISSION YIELD CURVE The probability that a particular pair of fission fragments will be produced by fission

BINDING ENERGY ATOMIC NUMBER ENERGYENERGY MOST STABLE ELEMENT (Fe)