11 OBJ 3 − Operational Health Physics. 2 Sources of Radiation Sources and dose contributions: – Terrestrial (7%) – Space (Cosmic/Solar) (11%) – Internal

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– 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

Sources mrem/yr

Ubiquitous

Terrestrial 21

Space(Cosmic/Solar) 33

Internal Emitters 29

Radon 228

Man-Made

Nuclear Fallout <1

Medical 300

Consumer Products 13

Nuclear Facilities<1Industrial, security, medical,

educational and research

Total ≈ 624

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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

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– Most common forms• Tritium gas (HT)• Tritium oxide, also called “tritiated water”

– 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

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– 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:

HeHLinLi 42

31

*73

10

63

13


• 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)

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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)

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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

)129.6()115.7(11

167

),(*178

10

168 MeVMeVpNOnO pn

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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)

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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

)2936.1(4118

),(*4118

10

4018 MeVNArnAr n

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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

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– 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

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• 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

)1.320(5124

),(*5124

10

5024 keVCrCrnCr n

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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

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– 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)

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– 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)

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• Origin/Source– Produced from neutron activation of 54Fe– 54Mn – Produced by (n,p) charged particle

emission when 55Fe absorbs a thermal n

)8.834(11

5425

),(*5526

10

5426 keVpMnFenFe pn

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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


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• 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


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– 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

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– 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

)173.1()333.1(6027

),(*6027

10

5927 MeVMeVCoConCo n

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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

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– 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

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• 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

)2.151()840(8536

),(*8536

10

8436 keVkeVKrKrnKr n

)514()687(8536

),(*8536

10

8436 keVkeVKrKrnKr n

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PWR Plant Systems

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PWR Plant Systems – RCS

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PWR Plant Systems – PRS

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PWR Plant Systems – PRS

• System Functions– Absorbs coolant expansion when T – Makes up for coolant contraction when T – Provides overpressure protection for RCS

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PWR Plant Systems – CVCS

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PWR Plant Systems – CVCS

• System Functions– Purify Rx coolant using filters and demineralizers– Add and remove 10B as necessary– Maintain Pzr level

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PWR Plant Systems – RHR & CCW

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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

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PWR Plant Systems – ECC

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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.

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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

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BWR Plant Systems

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BWR Plant Systems – RWCU

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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

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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.

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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

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BWR Plant Systems – HPECCS

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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

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BWR Plant Systems – LPECCS

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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

Documents

11 OBJ 3 − Operational Health Physics. 2 Sources of Radiation Sources and dose contributions: – Terrestrial (7%) – Space (Cosmic/Solar) (11%) – Internal