OBJ 3 − Operational Health Physics

1. 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 • 40K • Space – ≈ 33 mrem/yr • Cosmic/galactic • Protons • Alphas • Solar • Protons

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

5. Sources of Radiation • Internal, Inhalation – ≈ 228 mrem/yr • 222Rn • α • β • 220Rn • 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 1963. • Medical Exposure – ≈ 300 mrem/yr • Diagnostic – X-rays • Nuclear Medicine • 99mTc • 123I • 60Co

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 • 3H • 14C • 85Kr

9. Sources of Radiation

10. Isotopes of Concern – 3H • What is it? • Only radioactive isotope of 1H • Nucleus consists of 1 p+and 2 n • Ordinary 1H atom – 1 p+ • 2H atom -- 1 p+and 1 n • 1H > 99.9% of all naturally occurring H • 2H comprises about 0.02% • 3H comprises about 10-16% of natural H

11. Isotopes of Concern – 3H • Most common forms • Tritium gas (HT) • Tritium oxide, also called “tritiatedwater” • Decay Mode • β-– 18.6 keV • Half-life – 12.35 yrs • Biological Data • Biological Half-life – 12 d • Effective Half-life – 11.97 d • Critical Organ – Soft Tissue

12. Isotopes of Concern – 3H • 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 3H produced per 1E4 fissions • Large commercial Rx produces approx. 2E4 Ci/yr • Produced in Rx by:

13. Isotopes of Concern – 3H • 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 – 16N • What is it? • One of 11 radioactive isotopes of Nitrogen • Nucleus consists 7 p+ and 9 n • Decay Mode • β-– 4.27 MeV, 10.44 MeV • γ– 6.129 MeV, 7.115 MeV • Half-life – 7.13 sec • Ordinary Nitrogen consists of • 14N – 7 p+ and 7 n (99.632% abundance) • 15N – 7 p+ and 8 n (0.368% abundance)

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

16. Isotopes of Concern – 41Ar • 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-– 1.198 MeV • γ– 1.2936 MeV • Ordinary Argon consists of • 36Ar – 18 p+ and 18 n (0.3365% abundance) • 38Ar – 18 p+ and 20 n (0.0632% abundance) • 40Ar – 18 p+ and 22 n (96.6003% abundance)

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

18. Isotopes of Concern – 51Cr • What is it? • One of 20 radioactive isotopes of Chromium • Nucleus consists of 24 p+ and 27 n • Decay Mode • Electron capture • γ– 320.1 keV • Half-life – 27.702 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 – 51Cr • Dose Rates • 1 mCi – 6.4 mrem/hr at 2 in. (5 cm) • Ordinary Argon consists of • 50Cr – 24 p+ and 26 n (4.345% abundance) • 52Cr – 24 p+ and 28 n (83.789% abundance) • 53Cr – 24 p+ and 29 n (9.501% abundance) • 54Cr – 24 p+ and 30 n (2.365% abundance

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

21. Isotopes of Concern – 54Mn • What is it? • One of 22 radioactive isotopes of Manganese • Nucleus consists of 25 p+ and 29 n • Decay Mode • Electron capture • γ– 834.8 keV • Half-life – 312.1 d

22. Isotopes of Concern – 54Mn • 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 • 55Mn – 25 p+ and 30 n (100% abundance)

23. Isotopes of Concern – 54Mn • 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 • 55Mn – 25 p+ and 30 n (100% abundance)

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

25. Isotopes of Concern – 58Co • 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 – 810.8 keV • Half-life – 70.88 d

26. Isotopes of Concern – 60Co • 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 – 1.3325 MeV, 1.1732 MeV • Half-life – 70.88 d

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

29. Isotopes of Concern – 85Kr • What is it? • One of 24 radioactive isotopes of Krypton • Nucleus consists of 36 p+ and 29 n • Decay Mode • Branch 1 • IT– 304.9 keV • β- – 840 keV • γ– 151.2 keV • Half-life – 4.48 hrs • Branch 2 • β- – 687 keV • γ– 514 keV • Half-life – 10.76 yrs

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

31. Isotopes of Concern – 85Kr • Origin/Source • Produced from neutron activation of 84Kr in reactor fuel • Also produced as fission product • 85Kr – Produced by (n,γ) radiative capture when 84Kr 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 10B 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.