APR1400 General Arrangement PDF

APR1400 General Arrangement 41  APR1400 Nuclear Steam Supply System in Containment 42  NSSS – Reactor Coolant System Loop configuration 1 Reactor vessel 1 Pressurizer 2 Steam generators 4 Recirculating Coolant Pumps 2 Hot l...

APR1400 General Arrangement 41  APR1400 Nuclear Steam Supply System in Containment 42  NSSS – Reactor Coolant System Loop configuration 1 Reactor vessel 1 Pressurizer 2 Steam generators 4 Recirculating Coolant Pumps 2 Hot legs, 4 Cold legs 43  NSSS – Reactor Vessel 4 Inlet nozzles, 2 Outlet nozzles and 4 Direct Vessel Injection (DVI ) nozzles. Provides barrier to fission product release Part of coolant system pressure boundary 44  NSSS – Steam Generator (SG) SG tube design No. of tubes per SG : 13,102 Plugging margin : 10 % Material : Inconel 690 Improved upper tube support bar and plate To reduce flow-induced vibration Modified primary outlet nozzle angle To improve stability of mid-loop operation 45  NSSS – Pressurizer Design values Total Free volume : 2,400 ft3 (67.9 m3) 4 POSRV Coolant volume at full power : 1,100 ft3 (31.1 m3) Nozzles Heater capacity : 2,400 kW Increased pressurizer volume Enhance capability against RCS transients Pilot Operated Safety Relief Valve (POSRV) 4 POSRVs Function both over-pressure protection and safety depressurization Reliable valve operation without chattering and leakage Low valve stuck-open susceptibility 46  NSSS – Reactor Coolant Pump (RCP) Type Vertical bottom suction Horizontal discharge Single stage impeller Motor-driven centrifugal pump Speed : 1,190 rpm Shaft seal assembly Two face-type mechanical seals Reduce the RCS pressure to volume control tank pressure Third face-type low-pressure vapor seal Withstand RCS pressure when RCP is stopped 47  Turbine & Generator Turbine Number : 1 double flow HP TBN, 3 double flow LP TBN Type : Tandem-Compound Turbine Speed : 1,800 rpm Output : 1,455 MWe Last Stage Blade : 52 inch LSB Generator Number : 1 Type : Direct Driven (conductor cooled) Voltage : 24 kV, 3Phase Frequency : 60 Hz 48  Reactor Power System Layout 49  Where the Thermal Energy (Heat) Comes From UO2 fuel pellet. Enriched to 3-5 percent U-235 50  Logarithmic Distance Scale (Meters) Electron ~ 10-17 meters ~ meters ~ 10-2 meters ~ 10-10 meters 10-25 10-20 10-15 10-10 10-5 100 105 1010 1 Neutron 1 meter ~ 10-15 meters ~ 105 meters Distance to sun ~ 10-9 ~ 10-14 meters meters ~ 1011 meters 51  Fundamental Nuclei ~10-14m Particles 4He 16O Proton + 235U Materials ~10-2m Neutron Machines (meters) - Crystal Atoms ~10-10m ~10-9m Structures +  +n+++ 52  Fundamental Particles Nuclei ~10-14m 4He The world is composed 16O of various subatomic Proton + particles 235U – Also referred to as fundamental particles Neutron To understand nuclear - reactions – We need to have a Atoms ~10-10m basic understanding of + some of these fundamental particles  +n+++ 53  Fundamental Particles (continued) Fundamental Particles For our purposes we will concern ourselves with only the following fundamental particles: Particle Symbol Charge Mass Half-life Proton + proton p +e 1.673×10-27 kg stable? neutron n 0 1.675×10-27 kg 10.4 min Neutron electron -, e- -e 9.109×10-31 kg stable positron + +e 9.109×10-31 kg stable - neutrino 0 ? stable photon  0 0 stable + 1 Electron charge (-e) = 1.6022×10−19 Coulomb  1 ampere = 1 Coulomb/sec = 6.24 ×1018 electrons/sec 54  Atomic Structure Atoms consists of a small, dense, positively charged nucleus surrounded by a cloud of negatively charged electrons. n+ Niels Bohr: Electrons rapidly travel around the e- nucleus in discrete orbits. An electron in one of these orbits (or shells) has a discrete amount of energy. Simplified representation of an Atomic nucleus contains atom. NOT to scale. – Positively charged protons and – Electrically neutral neutrons. Except for the atomic nucleus of hydrogen-1 which contains only one proton and no neutrons. Protons and neutrons are called nucleons. 55  Atomic Structure (continued) Chemical properties of an atom are determined by the number of electrons and their distribution around the nucleus. Nuclear properties of an atom are determined by +n+++ the atomic nucleus. It is responsible for all nuclear effects: radioactive transformation, nuclear energy, etc. Nucleus contains nearly all the mass of the atom. Subatomic particle Mass Proton 1.67262 ×10-27 kg Neutron 1.674929 ×10-27 kg Electron 9.10939 ×10-31 kg 56  Terminology and Notation A Atoms and nuclei are denoted as Z X X – symbol representing a chemical element. For example: H, C, O, Au, Na, U, etc. Z – atomic number: number of protons in the atomic n+ e- nucleus (also, number of electrons in an electrically neutral atom). A – atomic mass number: total number of nucleons Examples: in the nucleus. 235 Atomic nucleus consists of Z protons and N neutrons 92 U 6 3 Li N = A – Z neutrons. N – neutron number. 239 94 Pu Nuclide is a species of atom characterized by its atomic number Z and mass number A and the energy state of the nucleus. 57  Isotopes The atomic number Z (the number of protons in the nucleus) A uniquely identifies a chemical Z X element. Isotopes – nuclides with the same number of protons but different number of neutrons. n+ e- – Example: isotopes of carbon, 12C, 13C, 14C. 6 6 6 C-12, C-13, C-14 58  Forces Inside Atoms and Nuclei Electrostatic force described by Atom ~10-10m Coulomb's law: Like charges repel each other, opposite charges attract. This force holds atoms together: +n+++ In the nucleus, protons and neutrons are held together by a much stronger nuclear force (or strong force). Nuclei ~10-14m – Nuclear force has a very short range: ~10-15 4He meters. 16O – Nuclear force overcomes the repulsive (electrostatic) force acting between protons. – Nuclear force is responsible for release of 235U energy when a nucleus breaks apart. 59  Four Fundamental Forces Gravity – attractive force between masses. Weak force – associated with some radioactive decay modes. Electromagnetic force – exists between charged particles. Nuclear force (Strong force) - strong attractive force between all nucleons (protons and neutrons). The strength of these four fundamental forces range over ~40 orders of magnitude: Nuclear Electromagnetic Weak Gravity 1 1·10-2 1·10-15 1·10-39 60  Stability of the Nucleus The balance between the attractive and repulsive forces determines the stability of a nucleus. The most important factor is the neutron-to-proton ratio. For light nuclei, Z ~ N and their neutron-to-proton ratio is about one (N : Z is about 1:1). For nuclei with A > 40, more neutrons are needed to balance the repulsive forces between the protons. For stable atoms, the neutron-to-proton ratio approaches 1.5. If the nucleus has more neutrons than needed for stability or doesn’t have enough neutrons, the atom is unstable. An unstable nucleus will attempt to become stable by emitting particles or energy. -- Radiation 61  Band of Stability Source: adapted from http://en.wikipedia.org/wiki/File:Isotopes_and_half-life.svg 62  Radiation An unstable nucleus will attempt to become stable by emitting particles or energy. -- Radiation  Radiation is energy traveling through space or matter in the form of particles or electromagnetic waves. -, + Radiation includes: Alpha particles Beta-rays Gamma-rays n Neutrons Neutrinos  Cosmic rays 63  Radiation and Radioactivity Radiation is produced – via decay of a nucleus – as a byproduct of nuclear and atomic reactions Atoms with unstable nuclei are radioactive. They can spontaneously transform into other nuclides. As they do so, they emit radiation of one type or another. Terminology: – Radionuclide – a radioactive nuclide. – Radioisotope – a radioactive isotope. 64  Activity Source activity (A) – The rate of radioactive decay (decays/sec) – Common units Becquerel (Bq) – one Bq is one decay per second Curie (Ci) – one curie is equal to 3.7 x 1010 decays per second Calculating activity: A=N N = the number of radioactive atoms in the sample λ = the decay constant (Probability of decay per unit time per radioactive atom) 65  Decay Constant and Half-life Decay constant (λ) – Probability of decay per unit time per radioactive atom – λ is constant for all time and for all atoms of the same species ln( 2) 0.693 = = t1/ 2 t1/2 – Half-life (t1/2 ) of the radioactive atoms in a sample is The time required for half of the radioactive atoms in the sample to decay: N(t1/2) = ½ N(t=0) The time during which the activity of the sample decreases by a factor of two: A(t1/2) = ½ A(t=0) 66  Decay of a Radionuclide Sample 1.0 Sr-82 Normalized concentration of radioactive atoms, 0.9 T1/2 = 25.36 days 0.8 0.7 0.6 U-238 T1/2 = 4.47 x 109 years 0.5 N/N0 0.4 0.3 0.2 0.1 0.0 0 1 2 3 4 5 6 7 8 9 10 Time in units of half-life, t 1/2 67  Chart of the Nuclides http://atom.kaeri.re.kr/ton/nuc1.html A tabulated chart that lists the stable and unstable nuclides. The chart is a two-dimensional graph in which the nuclides are arranged with their atomic number Z along the vertical axis and their neutron number N along the horizontal axis. Each point (square) plotted on the graph represents the nuclide of a real or hypothetical chemical element. The chart offers a greater insight into the characteristics of isotopes than the periodic table, which shows only elements but not the isotopes. Z N 68  Isotopic Abundance Stable and unstable isotopes of various chemical elements are found in nature. Some isotopes of a given element are more abundant than other isotopes of the element. Isotopic abundances are given in atom percent. Abbreviation: a/o. In one million uranium atoms, how many atoms of each isotope are present? 238U : 99.2745 a/0 235U : 0.7200 a/0 234U : 0.0055 a/0 Z 69 N  Isotopic Abundance Example Uranium has three naturally occurring isotopes: 234U, 235U and 238U. Their abundances 0.0055%, 0.72% and 99.2745% respectively. In one million uranium atoms, how many atoms of each isotope are present? Expected numbers of atoms: – approximately 55 234U atoms – 7,200 235U atoms, and – 992,745 238U atoms. 70  Enriched and Depleted Uranium All isotopes of uranium have – The same chemical properties – different nuclear properties. Uranium with 3-5% 235U is used in most power reactors. Natural uranium ore is only 0.72% 235U. Enrichment is the process of increasing the proportion of a particular isotope. Enriched uranium is uranium in which the concentration of 235U is greater than in natural uranium ore. Depleted uranium is uranium in which the concentration of 235U is less than its natural value of 0.72%. 71  Stability of the Nucleus (Review) The balance between the attractive and repulsive forces determines the stability of a nucleus. 1 The most important factor is the neutron-to-proton ratio. 1 H For light nuclei, Z ~ N and their neutron-to-proton ratio is about one (N : Z is about 1:1). n + e- For nuclei with A > 40, more neutrons are needed to 12 C 6 balance the repulsive forces between the protons. For stable atoms, the neutron-to-proton ratio approaches 1.5 If the nucleus has more neutrons than needed for stability or doesn’t have enough neutrons, the atom is unstable. +n+++ An unstable nucleus will attempt to become stable by emitting particles or energy -- Radiation. 208 82 Pb 72  Radioactive Decay The figure shows all of the stable nuclides as a function Atomic Number (Z) Versus Neutron of Z (vertical axis) and N Number (N) for All Known Stable Isotopes (horizontal axis) 140 – Note that there are more neutrons Z=N Line 120 Neutron than protons in most nuclei Poor 100  – The extra neutrons provide + 80 nuclear stability Z 60 - There are only certain 40 Neutron combinations of N and Z that 20 Rich produce stable nuclei 0 0 20 40 60 80 100 120 140 – The rest are radioactive N Author: Dr. Charlton, NUEN, TAMU 73  Beta Decay + Neutron rich isotopes are typically β - emitters Atomic Number (Z) Versus Neutron Number (N) for All Known Stable Isotopes A Z X → A Z +1 Y +  + 00 e 0 −1 140 Z=N Line − − Neutron n ⎯⎯→ p + e + ve 120 Poor 100  80 + Neutron poor isotopes are Z generally β+ emitters (or 60 electron capture, E.C.) 40 - Neutron X → Y + 10 + 00 e A A 20 Rich Z Z −1 0 0 20 40 60 80 100 120 140 + + p ⎯⎯→ n + e + ve N Author: Dr. Charlton, NUEN, TAMU Fission products are typically neutron rich 74  Beta Decay (continued) Consider the excerpt from the Chart of the Nuclides Z N Source: http://atom.kaeri.re.kr/ton/nuc1.html The element sodium (Z=11) has various isotopes (N=11, N=12, N=13, …) only Na-23 (Z=11, N=12) is stable +  Na-22 decays by β+ emission p ⎯⎯ → n + e+ + ve Na-24 decays by β- emission − n ⎯⎯→ p + e + ve − 75  Beta Decay (continued) Often, the daughter nucleus is also unstable and will undergo an additional β- decay This leads to a decay chain: 20 8 O → 9F + 20  + 00 0 −1 20 9 F → Ne + 20 10 0 −1  + 0 0 – Where Ne-20 is stable Source:http://atom.kaeri.re.kr/ton/nuc1.html 76  Alpha Decay The mode of decay for any Atomic Number (Z) Versus Neutron isotope is determined by its Number (N) for All Known Stable Isotopes position on the chart of the nuclides. 140 120 Neutron Z=N Line Heavy elements are typically 100 Poor  α - emitters 80 + – An alpha particle is an Z 60 energetic helium nucleus (2 - protons and 2 neutrons) 40 Neutron 20 Rich A− 4 A Z X → Y +  Z −2 4 2 0 0 20 40 60 80 100 120 140 N Heavy elements might also Author: Dr. Charlton, NUEN, TAMU spontaneously fission 77  Gamma Decay Example Nuclides often emit gamma rays in addition to other radiations; these emissions usually serve to bring the 60Co product nucleus to its ground state 60Co decays as follows: 99+% 2.506 MeV 0.013% 60 27 Co → 60 28 Ni +  + 00 +  0 −1 0.12% 2.158 MeV 1.332 MeV Thus, most of the time 60Co emits two gamma rays of 1173 and 1332 keV 60Ni 60Cohas a half-life of 5.27 Author: Dr. Charlton, NUEN, TAMU years or t1/ 2 = 5.27 yrs 78  Atomic Weight Using the data below, compute the atomic weight of naturally occurring uranium. Uranium has three naturally occurring isotopes: 234U, γ(234U) = 0.0055%, M(234U) = 234.0409456 235U, γ(235U) = 0.72%, M(235U) = 235.0439231 238U, γ(238U) = 99.2745%, M(238U) = 238.0507826 M(U) = (0.0055 * 234.041 + 0.72 * 235.044 + 99.2745 * 238.051) / 100 = 238.0289127 = 238.03 79  Atomic Mass Unit, Moles, and Avogadro Atomic Mass Unit (amu) – numerically equivalent to the atomic weight of an atom – one-twelfth the mass of the neutral carbon-12 atom 1 1 amu =  m(12 C ) 12 1 amu = 1.66057 × 10-24 g Mole – equal to the quantity containing as many elementary units as there are atoms in 12 grams of 12C Avogadro’s number – the number of atoms or molecules in one mole of any substance: NA = 6.022 × 1023 mol-1 Example: One mole of carbon-12 has a mass of exactly 12 g. Hence, we can calculate the mass in grams of one atom of 12C: 12 g / (6.022 × 1023) = 1.99 × 10-23 g 80  Atomic and Nuclear Dimensions Neither atoms nor nuclei have a sharp outer boundary. U-238 Atomic radius represents the average distance between the nucleus and the boundary of the R electron cloud. It depends on the atomic number Z. The average radii are approximately the same for all atoms: about 200 x 10-12 m (picometers - pm) (Except for a few of the lightest atoms: H, B, C, N, etc.) Atomic Radius, RA ≈ 200 picometers Nucleus ~ sphere with radius = 200,000 fm R = 1.25 fm × A1/3 where A is the atomic mass number, U-238 and 1 femtometer = 1 fm = 10-15 m Nuclear Radius, RN RN = 1.25 * (238)1/3 fm RN = 7.75 fm An atom is mostly empty space. 81  Where does the Thermal Energy (Heat) Come From? Nuclear Fission 82  Mass and Energy The energy produced in nuclear systems is derived from Einstein’s famous formula: E = mc 2 where c = 2.9979 ×108 m/s is the speed of light. Mass and energy are equivalent, or convertible from one to another. 83  Rest-mass Energy of the Electron Rest-mass energy is the energy of a body at rest: E0 = m0c2 Rest-mass energy of an electron: – Rest-mass of an electron me = 9.10954×10-31 kg – Speed of light c = 2.9979 × 108 m/s. – Rest-mass energy of an electron: mec2 = (9.10954×10-31 kg)*(2.9979 × 108 m/s)2 = 81.871 ×10-15 kg-m2/s2 = 81.871 ×10-15 Joules (J) where J denotes joule: 1J = 1 kg-m2/s2 (units of energy) 84  Electron Volt The electron volt is another useful practical unit. One electron volt is the energy gained by an electron when it passes through a potential difference of one volt 1 eV = (1.602177 ×10-19 C)(1 Volt) 1 eV = 1.602177 ×10-19 Joules (J) AA Alkaline battery contains ~ 9,000 J of energy Rest-mass energy of the electron mec2 = 81.871 ×10-15 J = 51.0999 ×104 eV mec2 = 0.511 MeV 85  Energy Equivalent of 1 amu 1 amu = 1.66057 × 10-24 g Using Einstein’s formula: E = mc 2 ( ) 2 − 27  8 m = 1.66057 10 kg  2.9979 10   s = 931.5 MeV Recall: 1J = 1 kg·m2/s2 and 1 eV = 1.602177 ×10-19 J 86  Neutron-induced Fission A neutron is absorbed by a target nucleus A compound nucleus is formed in an excited state The compound nucleus fissions A1 n n A A+1 * Z1 W n Z X Z X A2 Z2 Y n Scission of the compound nucleus into three or more fragments also occurs, though it is rare (1 in 400) 87  Nuclear Chain Reaction U →( U) → Rb + 3 ( 01n ) * 1 0 n + 235 92 236 92 Cs + 140 55 93 37 ΔMc2 = (Initial Mass – Final Mass)∙ c2 = 210 MeV / fission The total energy released per fission is around 210 MeV 1 Watt = 6.24 E12 MeV/sec Self-sustaining nuclear chain reaction To generate 1 watt of power we need: 6.24 E12 MeV/sec 210 MeV/fission = 2.97 E10 fissions/sec How do we get that many fissions every second? 88  Fission Rate in 1400 MWe Nuclear Power Plant 210 MeV per fission on average 1 watt = 1 Joule/sec = 6.24 E12 MeV/sec 6.24 E12 MeV/sec = 2.97 E10 fissions/sec = 1 watt 2.1 E2 MeV/fission 1400 MW x E6 watts/MW x 2.97E10 fissions/watt-sec = 4.16 E19 fissions/sec BUT WAIT!! Something is missing…? 4.16 E19 fissions/sec X 3 = 1.25 E20 fissions/sec = 1400 MWe 89  Energy from Fission Particles Energy Energy Where Deposited Emitted Recovered (MeV) (MeV) Fission fragments 168 168 fuel Prompt neutrons 5 5 fuel, clad, coolant Prompt -rays 7 7 fuel, clad, coolant, shield Decay ’s 8 8 fuel Decay -rays 7 7 fuel, clad, coolant, shield Decay neutrinos 12 0 universe Capture -rays 0 3-12 fuel, clad, coolant, shield Total 207 198-207  - A1 n  n A A+1 * W Z1 X X n Z Z + A2 Y n Z2 90   Characteristics of Fission Reactions (continued) Fission fragments give up their internal energy in a series of steps – Prompt neutrons and gamma-rays within 10-14 to 10-12 sec – Around 10-11 sec, fission fragments come to rest – Above 10-3 sec, fission products begin chains of beta decays; some decay by neutron emission (delayed neutrons) © 1994, 2013 Encyclopaedia Britannica, Inc. 91  Fission Products Fission product distributions as a function of FP mass number tend Fission Product Distribution for to show a binomial distribution 235 U Thermal and 14 MeV Fission 1.0E+00 On average, a fissioning nuclide 1.0E-01 splits in half (i.e., two equal mass, equal charge products) 1.0E-02 – However, symmetric fission is in 1.0E-03 Fission Yield fact a rare event 1.0E-04 1.0E-05 Fission products tend to be 1.0E-06 neutron rich ( β- and γ-emission) 1.0E-07 0.0253 eV Fission products: 1.0E-08 14 MeV – Are biological hazards 1.0E-09 60 90 120 150 180 – Produce decay heat Mass Number – Are neutron poisons Author: Dr. Charlton, NUEN, TAMU 92  Fissile and Fissionable-But-Nonfissile Nuclides “Fissile” nuclides – Can undergo fission following the absorption of a zero-energy neutron (room temperature neutron). Examples: 233U, 235U, 239Pu, and 241Pu “Fissionable but non-fissile” nuclides – Can undergo fission if the incident neutron has some threshold value of kinetic energy Example: 232Th, 238U, 240Pu 93  Fertile Nuclides It is possible to manufacture certain fissile nuclides from non-fissile nuclides The non-fissile nuclides from which fissile isotopes can be produced by neutron absorption are said to be “fertile” Fissionable but non-fissile nuclides 232Th and 238U can be used to produce fissile nuclides: 233U and 239Pu − − Th (n,  ) Th ⎯⎯→ Pa ⎯⎯→ 232 233 233 233 U − − U(n,  ) U ⎯⎯→ Np ⎯⎯→ 238 239 239 239 Pu 94 List of Required Texts 1. U.S. NRC "Nuclear Reactor Concepts" Workshop Manual, http://www.nrc.gov/reading-rm/basic-ref/teachers/unit3.html – Nuclear Power for Energy Generation http://www.nrc.gov/reading-rm/basic-ref/teachers/01.pdf – The Fission Process and Heat Production http://www.nrc.gov/reading-rm/basic-ref/teachers/02.pdf – Pressurized Water Reactor Systems http://www.nrc.gov/reading-rm/basic-ref/teachers/04.pdf 2. DOE Fundamentals Handbook “Nuclear Physics and Reactor Theory”, http://www.hss.doe.gov/nuclearsafety/ns/techstds/standard /hdbk1019/h1019v2.pdf 95  References Lamarsh, J. R., and Baratta, A. J., “Introduction to Nuclear Engineering”, third edition, Prentice Hall, 2001 Turner, J. E., “Atoms, radiation, and radiation protection”, third edition, Wiley-VCH, 2007 DOE Fundamentals Handbook “Nuclear Physics and Reactor Theory”, http://www.hss.doe.gov/nuclearsafety/ns/techstds/ standard/hdbk1019/h1019v1.pdf 96 References U.S. NRC "Nuclear Reactor Concepts" Workshop Manual, http://www.nrc.gov/reading-rm/basic-ref/teachers/unit3.html – Nuclear Power for Energy Generation http://www.nrc.gov/reading-rm/basic-ref/teachers/01.pdf – The Fission Process and Heat Production http://www.nrc.gov/reading-rm/basic-ref/teachers/02.pdf – Pressurized Water Reactor Systems http://www.nrc.gov/reading-rm/basic-ref/teachers/04.pdf DOE Fundamentals Handbook “Nuclear Physics and Reactor Theory”, http://www.hss.doe.gov/nuclearsafety/ns/techstds/standard/ hdbk1019/h1019v2.pdf Lamarsh, J. R., and Baratta, A. J., “Introduction to Nuclear Engineering”, third edition, Prentice Hall, 2001 Stacey, W. M., “Nuclear Reactor Physics”, second edition, Wiley-VCH, 2007 97