11 OBJ 3 − Operational Health Physics

2 Sources of Radiation Sources and dose contributions: – Terrestrial (7%) – Space (Cosmic/Solar) (11%) – Internal Emitters (9%) – Internal exp from inhalation (73%)

3 Sources of Radiation Ubiquitous Background – Ubiquitous background radiation in U.S. provides effective dose per individual average of 311 mrem (3,110 μSv) (NCRP Report No. 160) – Terrestrial – ≈ 21 mrem/yr Soil, rock, geology – Uranium series – Thorium series – 40 K – Space – ≈ 33 mrem/yr Cosmic/galactic – Protons – Alphas Solar – Protons

4 Sources of Radiation – Internal Emitters – ≈ 29 mrem/yr 40 K 87 Rb 226 Ra 238 U 210 Po 14 C

5 Sources of Radiation – Internal, Inhalation – ≈ 228 mrem/yr 222 Rn – α – β 220 Rn – α – β

6 Sources of Radiation Man-Made Background – Nuclear Fallout – < 1 mrem/yr γ from global fallout from atmospheric weapons tests has been dramatically reduced by radioactive decay and weathering since major atmospheric testing ended in – Medical Exposure – ≈ 300 mrem/yr Diagnostic – X-rays Nuclear Medicine – 99m Tc – 123 I – 60 Co

7 Sources of Radiation Man-Made Background – Consumer Products – ≈ 13 mrem/yr Major portion of this exposure (≈ 70%) is due to radioactivity in building materials. Television and display monitors no longer employ cathode-ray tube components (most) and therefore X-ray emissions are essentially zero.

8 Sources of Radiation – Nuclear Facilities – < 1 mrem/yr 3 H 14 C 85 Kr

9 Sources of Radiation Sourcesmrem/yr Ubiquitous Terrestrial21 Space(Cosmic/Solar)33 Internal Emitters 29 Radon228 Man-Made Nuclear Fallout <1 Medical300 Consumer Products 13 Nuclear Facilities <1 Industrial, security, medical, educational and research Total ≈ 624

10 Isotopes of Concern – 3 H What is it? – Only radioactive isotope of 1 H – Nucleus consists of 1 p + and 2 n Ordinary 1 H atom – 1 p + 2 H atom -- 1 p + and 1 n – 1 H > 99.9% of all naturally occurring H – 2 H comprises about 0.02% – 3 H comprises about % of natural H

11 Isotopes of Concern – 3 H – Most common forms Tritium gas (HT) Tritium oxide, also called “tritiated water” – Decay Mode β - – 18.6 keV – Half-life – yrs – Biological Data Biological Half-life – 12 d Effective Half-life – d Critical Organ – Soft Tissue

12 Isotopes of Concern – 3 H – Origin/Source Naturally occurs as very small % of ordinary H in water, both liquid and vapor – Result of interaction of cosmic radiation with gases in the upper atmosphere – Readily incorporated into water and falls to earth as rain Fission product in nuclear weapons tests and nuclear power Rx with yield of 0.01% – About 1 atom 3 H produced per 1E4 fissions – Large commercial Rx produces approx. 2E4 Ci/yr Produced in Rx by:

13 Isotopes of Concern – 3 H How Is It Used? – Component in nuclear weapons to boost yield of both fission and thermonuclear (fusion) warheads – Tracer in biological and environmental studies – Agent in luminous paints (exit signs, airport runway lights, and watch dials)

14 Isotopes of Concern – 16 N What is it? – One of 11 radioactive isotopes of Nitrogen – Nucleus consists 7 p + and 9 n – Decay Mode β - – 4.27 MeV, MeV γ – MeV, MeV – Half-life – 7.13 sec – Ordinary Nitrogen consists of 14 N – 7 p + and 7 n (99.632% abundance) 15 N – 7 p + and 8 n (0.368% abundance)

15 Isotopes of Concern – 16 N Origin/Source – Interaction of neutron flux with reactor coolant – 16 N – Radioactive isotope produced by (n,p) charged particle emission when 16 O absorbs a thermal n

16 Isotopes of Concern – 41 Ar What is it? – One of 13 radioactive isotopes of Argon – Nucleus consists of 18 p + and 23 n – Half-life – 1.83 hrs – Decay Modes β - – MeV γ – MeV – Ordinary Argon consists of 36 Ar – 18 p + and 18 n (0.3365% abundance) 38 Ar – 18 p + and 20 n (0.0632% abundance) 40 Ar – 18 p + and 22 n ( % abundance)

17 Isotopes of Concern – 41 Ar Origin/Source – Produced from neutron activation of naturally occurring 40 Ar in air surrounding the Rx vessel PWR Releases – Purging containment building BWR Releases – Purging reactor drywell – Source for PWRs and BWRs ≈ 25 Ci/yr – 41 Ar – Produced by (n, γ ) radiative capture when 40 Ar absorbs a thermal n

18 Isotopes of Concern – 51 Cr What is it? – One of 20 radioactive isotopes of Chromium – Nucleus consists of 24 p + and 27 n – Decay Mode Electron capture γ – keV – Half-life – d – Biological Data Biological Half-life – 616 d Effective Half-life – 26.6 d Critical Organ – Lower large intestine and kidneys

19 Isotopes of Concern – 51 Cr – Dose Rates 1 mCi – 6.4 mrem/hr at 2 in. (5 cm) – Ordinary Argon consists of 50 Cr – 24 p + and 26 n (4.345% abundance) 52 Cr – 24 p + and 28 n (83.789% abundance) 53 Cr – 24 p + and 29 n (9.501% abundance) 54 Cr – 24 p + and 30 n (2.365% abundance

20 Isotopes of Concern – 51 Cr Origin/Source – Produced from neutron activation of 50 Cr found in stainless steel alloys – 51 Cr – Produced by (n, γ ) radiative capture when 50 Cr absorbs a thermal n

21 Isotopes of Concern – 54 Mn What is it? – One of 22 radioactive isotopes of Manganese – Nucleus consists of 25 p + and 29 n – Decay Mode Electron capture γ – keV – Half-life – d

22 Isotopes of Concern – 54 Mn – Biological Data Biological Half-life – 25 d Effective Half-life – 23 d Target Organ – Liver and GI Tract – Dose Rates 1 mCi – 188 mrem/hr at 2 in. (5 cm) 1 mcCi – 47 mrem/hr at 4 in. (10 cm) – Ordinary Manganese consists of 55 Mn – 25 p + and 30 n (100% abundance)

23 Isotopes of Concern – 54 Mn – Biological Data Biological Half-life – 25 d Effective Half-life – 23 d Target Organ – Liver and GI Tract – Dose Rates 1 mCi – 188 mrem/hr at 2 in. (5 cm) 1 mCi – 47 mrem/hr at 4 in. (10 cm) – Ordinary Manganese consists of 55 Mn – 25 p + and 30 n (100% abundance)

24 Isotopes of Concern – 54 Mn Origin/Source – Produced from neutron activation of 54 Fe – 54 Mn – Produced by (n,p) charged particle emission when 55 Fe absorbs a thermal n

25 Isotopes of Concern – 58 Co What is it? – One of 23 radioactive isotopes of Cobalt – Nucleus consists of 28 p + and 30 n – Decay Mode Electron capture β + – 474 keV γ – keV – Half-life – d

26 Isotopes of Concern – 60 Co What is it? – One of 23 radioactive isotopes of Cobalt – Nucleus consists of 28 p + and 32 n – Decay Mode Isomeric Transition – 58.6 keV β - – 318 keV γ – MeV, MeV – Half-life – d

27 Isotopes of Concern – 60 Co – Biological Data 50% that reaches blood, excreted right away (mainly in urine) 5% deposits in liver Remaining 45% deposits evenly in other tissues of the body Of 60 Co that deposits in the liver and other tissues – 60% leaves body with Biological Half-life of 6 days – 20% clears with Biological Half-life of 60 days – Remaining 20% retained much longer, Biological Half-life of 800 days

28 Isotopes of Concern – 60 Co – Dose Rates Curie-meter-rem rule of thumb 1 1 m = 1 rem/hr – Ordinary Cobalt consists of 59 Co – 27 p + and 32 n (100% abundance) Origin/Source – Produced from neutron activation of 59 Co – 60 Co – Produced by (n, γ ) radiative capture when 59 Co absorbs a thermal n

29 Isotopes of Concern – 85 Kr What is it? – One of 24 radioactive isotopes of Krypton – Nucleus consists of 36 p + and 29 n – Decay Mode Branch 1 – IT – keV – β- – 840 keV – γ – keV – Half-life – 4.48 hrs Branch 2 – β- – 687 keV – γ – 514 keV – Half-life – yrs

30 Isotopes of Concern – 85 Kr – Ordinary Krypton consists of 78 Kr – 36 p + and 42 n (0.35% abundance) 80 Kr – 36 p + and 44 n (2.28% abundance) 82 Kr – 36 p + and 46 n (11.58% abundance) 83 Kr – 36 p + and 47 n (11.49% abundance) 84 Kr – 36 p + and 48 n (57.0% abundance) 86 Kr – 36 p + and 50 n (17.3% abundance

31 Isotopes of Concern – 85 Kr Origin/Source – Produced from neutron activation of 84 Kr in reactor fuel – Also produced as fission product – 85 Kr – Produced by (n, γ ) radiative capture when 84 Kr absorbs a thermal n

32 PWR Plant Systems

33 PWR Plant Systems – RCS

34 PWR Plant Systems – PRS

35 PWR Plant Systems – PRS System Functions – Absorbs coolant expansion when T  – Makes up for coolant contraction when T  – Provides overpressure protection for RCS

36 PWR Plant Systems – CVCS

37 PWR Plant Systems – CVCS System Functions – Purify Rx coolant using filters and demineralizers – Add and remove 10 B as necessary – Maintain Pzr level

38 PWR Plant Systems – RHR & CCW

39 PWR Plant Systems – RHR & CCW System Functions – Residual Heat Removal (RHR) Used when cooling down for maintenance/outage When S/Gs can no longer remove decay heat by producing steam, RHR provides forced cooldown – Component Cooling Water (CCW) Provides fresh water cooling to plant components

40 PWR Plant Systems – ECC

41 PWR Plant Systems – ECC System Functions – Provides core cooling to minimize fuel damage following LOCA Injects large amounts of cool, borated water into RCS – Provides extra n poisons to ensure Rx remains S/D following C/D associated with steam line rupture.

42 PWR Plant Systems – CBC

43 PWR Plant Systems – CBC System Functions – Provides containment building cooling in the event of a primary or secondary break inside the building – Pumps water into spray rings located in the upper part of the containment – Water droplets condense steam reducing both temp and press in the bldg

44 BWR Plant Systems

45 BWR Plant Systems – RWCU

46 BWR Plant Systems – RWCU System Functions – Removes fission products, corrosion products and other soluble and insoluble impurities from the reactor coolant

47 BWR Plant Systems – RHR

48 PWR Plant Systems – RHR System Functions – Used when cooling down for maintenance/outage – When dumping steam into condenser can no longer remove decay heat, RHR provides forced cooldown via the service water cooling system.

49 BWR Plant Systems – RCIC

50 PWR Plant Systems – RCIC System Functions – Provide M/U water to Rx vessel for core cooling when main steam lines are isolated and normal water supply is lost.

51 BWR Plant Systems – SLCS

52 PWR Plant Systems – SLCS System Functions – Injects neutron poison (Boron) into Rx vessel to S/D the reactor independent of control rods – Keeps Rx S/D as plant is cooled to maintenance temps

53 BWR Plant Systems – HPECCS

54 PWR Plant Systems – HPECCS System Functions – Independent emergency core cooling system that provides M/U water to the Rx vessel for core cooling under small and intermediate size LOCAs

55 BWR Plant Systems – LPECCS

56 PWR Plant Systems – LPECCS System Functions – Consists of two separate and independent systems Core Spray System Low Pressure Coolant Injection (LPCI) – Core spray system sprays water on top of fuel assemblies – LPCI provides M/U water to Rx vessel for core cooling under LOCA conditions