INFO-0718,Radiation Safety Officers Handbook
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Advisory Committee on Radiological Protection Radiation Safety Officers Handbook Part A INFO-0718 October 2000 On May 31, 2000, the Atomic Energy Control Board became the Canadian Nuclear Safety Commission. In this document, references to the Atomic Energy Control Board or to the AECB should be read — unless the context requires otherwise — as references to the Canadian Nuclear Safety commission (CNSC). The Canadian Nuclear Safety Commission (CNSC), and its predecessor the Atomic Energy Control Board, has made use of advisory committees of independent experts to assist it in its decision making process. The Commission has two senior level scientific committees charged with providing independent advice on principles, standards and general practices related to radiation protection and the safety of nuclear facilities. The two committees are the Advisory Committee on Nuclear Safety (ACNS) and the Advisory Committee on Radiation Protection (ACNS). The Canadian Nuclear Safety Commission publishes many of the reports of its advisory committees. Publication by the CNSC does not imply endorsement of the content, nor acceptance of any recommendations made therein. Advisory Committee on Radiological Protection Radiation Safety Officers Handbook Part A INFO-0718 October 2000 For Information on the indepedent advisory committees contact: Advisory Committees of the Canadian Nuclear Safety Commission, Ottawa, Ontario K1P 5SP. RADIATION SAFETY OFFICER'S HANDBOOK PART A TABLE OF CONTENTS CHAPTER Al RADIOACTIVITY .........................................Al-l Al.l Atoms - the building blocks of matter .............Al-l Al.2 The structure of the Atom .......................Al-3 Al.3 Radioactive Transformations .....................Al-6 Al.4 The Nuclear Shell Model and Isomeric Transitions ....................................Al-S Al.5 Alpha Decay ..................................Al-l0 Al.6 Other Radiations ..............................Al-ll Al.7 Decay Schemes ................................Al-ll Al.S Making Radionuclides .........................Al-l2 Al.9 Activity ......................................Al-l4 Al.l0 Exponential Decay .............................Al-l4 Al.ll Complex Decays ..............................Al-l5 Al.l2 Series Decay ..................................Al-l7 CHAPTER A2 RADIATION INTERACTIONS WITH MATTER ...............A2-l A2.l Introduction ...................................A2-l A2.2 Charged Particles ...............................A2-2 A2.3 Photons .......................................A2-4 TABLE OF CONTENTS A2.4 Attenuation of Photons ..........................A2-6 A2.5 Energy Transfer ................................A2-7 A2.6 Sources of Radiation Exposure ...................A2-S CHAPTER A3 RADIATION DETECTORS .................................A3-l A3.l Introduction ...................................A3-l A3.2 Pocket Dosimeter ...............................A3-l A3.3 Gaseous Ion Chambers ..........................A3-2 A3.4 Current Ionization Chamber .....................A3-2 A3.5 The Geiger-Miller Counter ......................A3-4 A3.6 The G.M. Counter as an Exposure Meter ...........A3-5 A3.7 Semiconductor Detectors ........................A3-6 A3.S Scintillation Detectors ...........................A3-S A3.9 Energy Spectroscopy ...........................A3-l0 A3.l0 Thermoluminescent Dosimetry (TLD) ............A3-ll A3.ll Quantitative Factors .........................A3-l3 CHAPTER A4 RADIATION DOSIMETRY UNITS ..........................A4-l A4.l Introduction ...................................A4-l A4.2 Activity .......................................A4-2 A4.3 Exposure ......................................A4-2 A4.4 Exposure Rate Constant .........................A4-3 A4.5 Absorbed Dose .................................A4-3 A4.6 Equivalent Dose ................................A4-4 A4.7 Effective Dose ..................................A4-4 A4.S Committed Dose ...............................A4-5 A4.9 Annual Limit on Intake (ALI) ....................A4-5 A4.l0 Derived Quantities .............................A4-5 A4.ll Problems with Exposure .........................A4-5 CHAPTER A5 CHEMICAL EFFECTS OF RADIATION ..................A5-l CHAPTER A6 BIOLOGICAL EFFECTS OF RADIATION ....................A6-l A6.l Introduction ...................................A6-l A6.2 The Genetic effects of Radiation ..................A6-4 TABLE OF CONTENTS CHAPTER A7 ADVISORY BODIES ......................................A7-l A7.l Introduction ...................................A7-l A7.2 The I.C.R.P. ....................................A7-l A7.3 The A.C.R.P., A.C.N.S. and G.M.A. ...............A7-5 A7.4 The I.C.R.U. ...................................A7-S A7.5 The I.A.E.A. ...................................A7-9 A7.6 The N.C.R.P. ...................................A7-9 A7.7 U.N.S.C.E.A.R. ................................A7-l3 A7.S B.E.I.R. .......................................A7-l4 A7.9 Associations ..................................A7-l4 APPENDIX XAl MATHEMATICAL REVIEW ............................. XAl-l XAl.l Exponential .................................. XAl-l XAl.2 Logarithms .................................. XAl-l XAl.3 Differentiation ............................... XAl-l XAl.4 Integration .................................. XAl-2 XAl.5 Exponential "e" .............................. XAl-3 XAl.6 Natural Logarithms .......................... XAl-3 XAl.7 Radioactive Decay ........................... XAl-4 XAl.S Photon Attenuation .......................... XAl-6 XAl.9 Parent/Daughter Decay ...................... XAl-6 APPENDIX XA2 SAMPLE CALCULATIONS .............................. XA2-l XA2.l Activity ..................................... XA2-l XA2.2 Exposure .................................... XA2-3 XA2.3 Shielding .................................... XA2-4 XA2.4 Absorbed Dose .............................. XA2-5 XA2.5 Effective Dose ................................ XA2-6 XA2.6 Committed Dose ............................. XA2-7 XA2.7 ALI, DIL .................................... XA2-7 XA2.S Internal Dosimetry ........................... XA2-7 CHAPTER Al RADIOACTIVITY cannot last. The Coulombic force between the two Al.l ATOMS -THE BUILDING positively charged protons will immediately split BLOCKS OF MATTER them apart, a process known as "nuclear fission". To produce a lasting or stable union between the If we push two hydrogen atoms gently together the electrons will form a "covalent bond" and we will two protons we require some kind of "glue", sufficiently strong to resist the Coulombic have a molecule of hydrogen, usually written chemically as H . repulsion. 2 electron proton Hydrogen atom : The negative electron is held in Helium atom? Not quite ! The repulsion of the two orbit around the positive proton by the electric positive protons would split the nucleus. (Coulomb) force. � � Hydrogen molecule : Two atoms held together by a Helium atom : The neutrons bind the protons together. covalent bond. To produce a new kind of atom, we have to push Enter the neutron, a particle very like the proton, the two hydrogen atoms even closer, so that their but electrically neutral. Neutrons attract protons nuclei fuse together to form a single nucleus, a and other neutrons via a new type of force or process called "nuclear fusion". But this nucleus "interaction", called simply "the Strong Force". Radiation Safety Officer's Handbook CHAPTER AJ AJ-J If we add two neutrons to our new nucleus, the hydrogen. To distinguish it from ordinary neutron "pull" will balance the proton "push" and hydrogen, it is called "hydrogen-3" (abbreviated to we will have a stable atom of the element helium. H-3 or 3H) and is said to be an "isotope of hydrogen". This particular isotope of hydrogen has been given the name "tritium", because it has Four Universal forces three "nucleons" (i.e. protons and neutrons) in its nucleus. Force Strength -39 Gravity 6x10 -5 Weak nuclear 10 Electromagnetic 1/137 G G Strong nuclear 1 By fusing another hydrogen building block to the helium atom, we can create an atom of lithium, and Tritium atom : Three nucleons in the nucleus so on up the periodic table. Each time we add another proton to the nucleus, we must also add an appropriate number of neutrons to balance the extra The tritium nucleus has too many neutrons, and is repulsion. therefore unstable. Eventually, one of the excess neutrons will change into a proton. This "nuclear Neutron I Proton numbers in stable nuclei transformation" obeys the law of conservation of charge, which says that the total charge before and Nuclide No. Protons No. Neutrons after a transformation must be the same. Therefore, helium 2 2 to change a neutron (0 charge) into a proton (+1), an electron (-1) is also created, and ejected from the neon 10 10 nucleus. calcium 20 20 zinc 30 34 When first detected earlier in this century, the fast tin 40 50 moving electrons ejected during this process were niobium 60 90 named "beta rays", and the atoms from whence they came were said (by Marie Curie) to be mercury 80 122 "radioactive". What would happen if we added too few neutrons, or too many? Then the proton push and the neutron pull would be out of balance, and we would have an unstable nucleus. ββ A simple example of this is obtained by adding two Beta decay : neutrons to the nucleus of a hydrogen atom. When neutron becomes a proton by ejecting an electron we specify the number of neutrons and protons in a nucleus, as we have done here, we are defining a particular "nuclide". It appeared, at first, as though