Nishina School at RIKEN RIBF 20111011 Radiation Safety

Nishina School at RIKEN RIBF 2011/10/11 Radiation Safety Y. Uwamino Safety Management Group

Gas-filled detectors gas-filled chamber voltage source ionizing radiation - anode (+) + cathode (-) 大学等放射線施設協議会 electrical current measuring device

Radioactive Decay Series Th series (4 n series) U series (4 n+2 series)

Interaction with matter 大学等放射線施設協議会

Ionization and excitation Free electron Ionization Ion pair Interaction Charged particle Cation energy dissipation Excitation ground state 大学等放射線施設協議会 excited state

Charged particles (a 2+, b-, b+) Energy dissipation (Continuous slowdown) Non-charged particles g ray x ray high-speed electron interaction (photoelectric effect, Compton scattering, pair production) high-speed charged nucleus neutron interaction (n, p), (n, a), etc. 大学等放射線施設協議会

Radiation-Related Quantities and Units radiation matter Absorbed Dose : Gray (Gy) - The energy absorbed per unit mass of the material - A fundamental dosimetric quantity (physical unit) - Regardless of the kind of radiation - 1 Gy = 1 J/ kg - Dose not reflect the degree of biological effects To calculate the risk of irradiation to the human body Equivalent Dose Effective Dose : Sievert (Sv) 大学等放射線施設協議会

2. Linear Energy Transfer (LET) (ke. V/mm) 【d. E/dx (Me. V/mm)】 radiation Ionization e. P+ The energy transferred per given distance of track Low LET radiations (X, γ, β) High LET radiations (α, neutron) ＝ Sparsely ionizing Densely ionizing Less biological effect More biological effect Linear Energy Transfer (LET) 大学等放射線施設協議会

DNA is the Target of Radiations Indirect action H 2 O OH. Ionizing (free radical) e. P+ Low LET radiations (X, γ, β) Direct action Ionizing e. P+ 2 nm 大学等放射線施設協議会 High LET radiations (α, neutron)

Equivalent Dose & Effective Dose Equivalent Dose (HT ) : Sievert (Sv) ･ a measure of biological effects on a particular tissues or organs ･ HT = ∑w. R ・DT, R R w. R ：Radiation weighting factor DT, R ：Mean absorbed dose for a tissue or organ (Gy) Radiation weighting factor (w. R) Radiation Weighting Factor γ rays & Ｘrays 1 Beta rays 1 Proton 2 α rays, fission fragments, heavy ion 20 Neutrons Continuous function of the energy (ICRP 2007) 大学等放射線施設協議会

Equivalent Dose & Effective Dose (E) : Sievert (Sv) Stochastic effects ･ a measure of biological effects throughout the body (cancers or genetic effects) ･ E = ∑w ・H = ∑w ・D T T T R T, R T T R Tissue weighting factors Tissue/Organ HT : Equivalent dose for tissues and organs w. T： Weighting factor for organs or tissues Annual average dose person Doctors 0. 24 m. Sv Nurse 0. 12 m. Sv Radiotherapy technicians 0. 68 m. Sv Those engaged in research 0. 01 m. Sv Nuclear power plant worker 1. 3 m. Sv 大学等放射線施設協議会 Red bone marrow Colon Lung Stomach Breast Gonads Bladder Esophagus Liver Thyroid Bone Brain Salivary gland Skin Others Weighting factor 0. 12 0. 08 0. 04 0. 01 0. 12 (ICRP 2007)

Effects of Radiation on Human Health ISBN 978 -4 -905025 -12 -2 大学等放射線施設協議会 113 -0032 東京都文京区弥生 2 -11 -16 東京大学アイソトープ総合センター内 電話: 03 -5841 -3058 Fax: 03 -5841 -3050 E-mail: kyogikai@ric. u-tokyo. ac. jp

Classification of Biological effects of Radiations on the Human Body ・Acute Effects vs. Late Effects ・Deterministic Effects vs. Stochastic Effects ・Somatic Effects vs. Genetic Effects 大学等放射線施設協議会

Classification of Biological effects of Radiation on the Human Body ・Acute Effects vs. Late Effects ・Deterministic Effects vs. Stochastic Effects ・Somatic Effects vs. Genetic Effects 大学等放射線施設協議会

Acute Effects Symptoms of acute effects and dose delivered (Whole body, single exposure to gamma rays (or X-rays)) Dose (Gy: J/kg) 0. 25 or less 0. 5 Symptoms Almost no clinical symptoms Temporary reduction of white blood cells (lymphocytes【リンパ球】) 1 Nausea【悪心】, vomiting, whole-body languor【倦怠】, substantial reduction of lymphocytes 1 Death to 5% 4 Death to 50% within 30 days 【damage on bone marrow】 6 Death to 90% within 14 days 【damage on intestines】 7 Death to 100% 大学等放射線施設協議会

Late Effects Cataracts Cornea : clouding of the lens of the eye Lens ・Latent period: several years to a few decades 【潜伏期間】 ・Do not occur below a single exposure dose of 2 Sv Optic nerve Eye Cancers ・Latent period: several years to a few decades Genetic effects ・Could be ･ But not verified in human beings so far 大学等放射線施設協議会 Use a appropriate shield in front of your eyes

Classification of Biological effects of Radiation on the Human Body ・Acute Effects vs. Late Effects ・Deterministic Effects vs. Stochastic Effects ・Somatic Effects vs. Genetic Effects 大学等放射線施設協議会

Deterministic Effects vs. Stochastic Effects Deterministic Effects - Acute effects - Cataract 大学等放射線施設協議会 Stochastic Effects - Cancer, leukemia - Genetic effects

Deterministic effects Projected threshold estimates of the acute absorbed dose for 1% morbidity after 【罹患率】 whole body gamma ray exposures Effect Temporary sterility Organ/Tissue Time to develop effect Absorbed dose (Gy) Testes 3 -9 weeks 〜 0. 1 Testes 3 weeks 〜 6 Ovaries < 1 week 〜 3 Depression of blood forming process Bone marrow 3 -7 days 〜 0. 5 Skin reddening Skin (large areas) 1 -4 weeks < 3 -6 Skin burns Skin (large areas) 2 -3 weeks 5 -10 Temporary hair loss Skin 2 -3 weeks 〜 4 Cataract (visual impairment) Eye Several years 〜 1. 5 Permanent sterility ICRP publication 103, pp 168, Table A. 3. 4, 2007 大学等放射線施設協議会

Risk Estimate for Cancers (Stochastic Effect) Data of the atomic bomb survivors of Hiroshima and Nagasaki Incidence of cancer Occurrence due to exposure Spontaneous occurrence （about 30％） extrapolation on the Linear Non-Threshold assumption 0 0. 2 3 Radiation exposure (Sv)

Risk Coefficients (stochastic effects) Detriment-adjusted nominal risk coefficients after exposure to radiation at low dose rate Exposed population Cancer Heritable effects 【遺伝的影響】 Total Whole population 5. 5 x 10 -2/Sv 0. 2 x 10 -2/Sv 5. 7 x 10 -2/Sv Adult workers 4. 1 x 10 -2/Sv 0. 1 x 10 -2/Sv 4. 2 x 10 -2/Sv ICRP publication 103, pp 53, Table 1, 2007 大学等放射線施設協議会

Effective Dose Limits and Tissue Equivalent Dose Limits for Radiation Workers (including Researchers) Japanese law Effective dose limit Men 50 m. Sv/year; 100 m. Sv/5 years (RIKEN: 20 m. Sv/year) Women 5 m. Sv/3 months Pregnant women * 1 m. Sv as internal exposure 1) Lens of the eye 150 m. Sv/year 2) Skin 500 m. Sv/year 3) Abdomen of pregnant women* 2 m. Sv Tissue equivalent dose limit *From the confirmation of pregnancy to delivery for Non-Radiation Workers Effective dose limit Japanese law 250 m. Sv/3 months (1 m. Sv/year) (RIKEN: 50 m. Sv/year)

How to reduce exposures.

External Exposures vs. Internal Exposures Inhalation Trough the skin Ingestion External exposure Internal exposure 大学等放射線施設協議会

Protecting Against External Exposure 3 principles As near to the radiation source as possible Shield radiation sources. Shielding Shield Stay as far away as possible. Distance Dose rate = K/ R 2 K: constant R: distance Time Keep exposure time short ! 大学等放射線施設協議会

1. Penetrating Ability of Radiations Paper α P+n n P+ β γ e- Neutron radiation Aluminum Acrylic resin n 大学等放射線施設協議会 Lead H 2 O (Hydrogen rich)

Mass attenuation coefficients (mm) for photons

Laws and Ordinances Concerning Prevention of Radiation Hazards ISBN 978 -4 -905025 -13 -9 大学等放射線施設協議会 113 -0032 東京都文京区弥生 2 -11 -16 東京大学アイソトープ総合センター内 電話: 03 -5841 -3058 Fax: 03 -5841 -3050 E-mail: kyogikai@ric. u-tokyo. ac. jp

• Atomic Energy Basic Law (1955) Article 1 【basic policy】 The research, development and utilization of atomic energy shall be limited to peaceful purposes, aimed at ensuring safety and performed independently under democratic management, the results therefrom shall be made public to contribute to international cooperation.

• Radioisotopes, Accelerators: Laws concerning Prevention of Radiation Hazards due to Radioisotopes, etc. (1957) [concerned authority : Ministry of Education, Culture, Sports, Science and Technology] • Reactors, Nuclear Fuel: Laws concerning the Control of Nuclear Source Material, Nuclear Fuel Material, and Nuclear Reactor (1957) [concerned authority : Ministry of Education , Culture, Sports, Science and Technology] • Labor Safety: Labor Safety Hygiene Laws (1972) (X-ray generators of energy<1 Me. V) [concerned authority : Ministry of Health, Labor and Welfare]

Measurement at RIKEN to the Fukushima Nuclear Accident

Structure of Boiling Water Reactor (BWR) Spent Fuel Storage Pool Reactor Core Pressure Vessel Reactor Containment Vessel Pressure Suppression Pool 32

What kinds of nuclides are produced in the reactor? Fission reaction 235 ～ 140 Neutron Yield 1 Uranium ～ 90 Fission products Mass number Dominant products 95 Zr(64 d 6. 5%)、95 Mo(Stable 6. 5%)、134 Xe(Stable 7. 9%)、134 I(53 m 7. 8%)、 131 I(8. 0 d 2. 9%)、132 Te(3. 2 d 4. 3%)、133 Xe(5. 2 d 6. 7%)、137 Cs(30 y 6. 2%)、…

Measurement with monitoring posts 90 Sr, 239 Pu 133 Xe Rainfall 131 I Dose rate 137 Cs 132 Te Date

Accumulated dose 133 Xe passes in a flash, and dose contribution is nearly zero. In Wako, dose rate due to accident was 0. 1μSv/h on Mar. 30. Breakdown: 22% 25% 38% 15% from 132 Te(+132 I) [Half life=3. 2 d] 131 I [Half life=8. 0 d] 134 Cs [Half life=2. 1 y] 137 Cs [Half life=30 y] Yearly accumulated dose from Mar. 15 is 0. 55 m. Sv, (including internal exposure due to radioactivity in air; 0. 05 m. Sv. Indoor exposure is 0. 01 to 0. 05 of the above in a large building, 0. 4 in a small wooden house.

Exposure by the Natural Radiations (world average, UNSCEAR 2008） Cosmic ray（galaxy, sun） 0. 39 m. Sv/y Terrestrial（U, Th） 0. 48 m. Sv/y Food（40 K in natural potassium） 0. 29 m. Sv/y Radon in the air 1. 26 m. Sv/y （222 Rn/220 Rn from 238 U/232 Th） 合計 Terrestrial radiation Ramsar, Iran Guarapari, Brazil Kerala, India 陽江（near広州） average 2. 4 m. Sv/y 10. 2 m. Sv/y 5. 5 3. 8 3. 5 highest 260 m. Sv/y 35 35 5. 4

In case of fire • First, yell out “FIRE!” • Evacuate to a safe place. • Call extension 111 to guard station. Inform place, situation, your name and lab, telephone number you can be contacted, and the fact that the fire is in radiation controlled area. • Gather for a roll-call in front of RIBF Bldg. • If at all possible, help prevent fire from spreading.

Please enjoy stay at RIKEN.