1. Y. Uwamino Safety Management Group
Nishina School 2010/10/12
Radiation Safety
Y. Uwamino
Safety Management Group

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

3. 1. Penetrating Ability of Radiations
Aluminum
Acrylic resin
H2O
(Hydrogen rich)
Paper
Lead P+ n α n P+ β e- γ
The first factor is penetrating ability.
Penetrating ability differs depending on radiations.
This slide shows penetrating ability of each radiation.
And This is also helpful for the radiation protection.
Alpha rays can easily be shielded by paper and Nylon globe. We can easily protect ourselves from external radiation, but we must take care not to inhale the alpha particle. Once it’s inhaled, sever internal contamination is followed, because it hurts directly the epithelial cell of the lung.
Beta rays penetrate the paper but are blocked by Aluminum or acrylic resin.
Gamma ray is blocked by lead.
Regarding the neutron, it penetrate the lead. Only the way to block is to use atom of a similar atomic weight, that is Hydrogen and thus water.
Neutron
radiation n
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4. Effects of Radiation on Human Health 4 ISBN978-4-905025-12-2
東京都文京区弥生 東京大学アイソトープ総合センター内 電話: 　Fax:
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5. 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
Now let’s move onto the classifications of biological effects.
There are various types of classifications of the biological effects of radiation on the human body. I will show you some of them.
Biological effects can be divided into acute effects and late effects, based on the time from exposure.
Another way of classification is deterministic effects and stochastic effects. I will explain these two classifications later in details.
In addition, radiation effects can be divided into somatic effects and genetic effects.
In somatic effects, the effects of radiation appear in the person who has been exposed.
In contrast, in genetic effects, they appear in his or her offspring.
Now let’s move onto the detailed explanation of the first one and second one.
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6. 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
Firstly, I will show you acute effects and late effects of radiations on the human body.
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7. Acute Effects Symptoms of acute effects and dose delivered
(Whole body, single exposure to gamma rays (or X-rays))
Dose (Gy: J/kg)
Symptoms
0.25 or less
Almost no clinical symptoms
0.5
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
Death to 5% 4
Death to 50% within 30 days 6
Death to 90% within 14 days 7
Death to 100%
As an example of acute effects in the case of whole-body exposure, single exposure to gamma rays or X-rays will be explained here.
Symptoms differ among individuals, but typical cases are shown here.
No clinical symptoms are recognized at doses of 0.25 Gy or less.
A dose of 0.5 Gy causes a temporary reduction in the number of white blood cells, and the cell count returns to normal after a while.
A dose about 4 Gy brings death within 30 days to 50% of those exposed.
At 7 Gy, the probability of death is 100%.
But, don’t be afraid too much, because you will not use such high dose of radiation especially in biological or chemical researches.
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8. Late Effects Cataracts Eye Cancers Genetic effects Cornea Lens
: clouding of the lens of the eye
・Latent period: several years to a few decades
・Do not occur below a single exposure dose
of 2 Sv
Lens
【潜伏期間】
Optic nerve
Eye
Cancers
・Latent period: several years to a few decades
Typical late effects are cataracts and cancers for those who have been exposed, and genetic effects for their offsprings.
Cataracts is the clouding of the lens of the eye.
The latent period for cataracts ranges from several years to a few decades, varying with dose.
Don’t be afraid too much, but keep your eyes away from the radiation source as far as possible, or use an appropriate shield in front of your eyes to prevent cataracts in the future.
Latent period for cancers varies according to the exposed organs or tissues, age at the time of exposure and dose, but typically ranged from several years to a few decades.
As regarding genetic effects, animal studies have shown that radiation effects appears in offspring of those who are exposed.
But genetic effect caused by radiation have not been verified in human beings.
According to the longitudinal investigation for the victims of atomic bombs in Hiroshima or Nagasaki, Japan, there is no genetic effects on their offspring.
Genetic effects
・Could be
･ But not verified in human beings so far
Use a appropriate shield
in front of your eyes
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9. 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
The next classification I will explain is “deterministic effects” and “stochastic effects”.
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10. Deterministic Effects vs. Stochastic Effects Deterministic Effects
Radiation effects on the human body can be divided into deterministic effects and stochastic effects, depending on the relationship between the dose received and how the effect appears.
Threshold values, as shown here, have been determined for acute effects and cataracts. Beyond the threshold dose of exposure, the larger the dose is, the greater the rate of occurrence, and the greater the degree of effects will be. In this kind of case, effects are called “deterministic effects”.
In contrast, occurrences of cancer as well as genetic effects simply increase with the dose delivered as shown here. No threshold values are thought to be exist, and severity of dose has nothing to do with dose. These kinds of effects are called “stochastic effects”.
“Stochastic” means “probabilistic”.
Deterministic Effects
Stochastic Effects
- Acute effects
- Cataract
- Cancer, leukemia
- Genetic effects
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11. Deterministic effects
Projected threshold estimates of the acute absorbed dose for 1% morbidity after whole body gamma ray exposures
【罹患率】
Effect
Organ/Tissue
Time to develop effect
Absorbed dose (Gy)
Temporary sterility
Testes
3-9 weeks
〜 0.1
Permanent sterility
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
2-3 weeks
5-10
Temporary hair loss
Skin
〜 4
Cataract (visual impairment)
Eye
Several years
〜 1.5
The threshold dose is defined as the acute absorbed doses for 1% incidents of morbidity and mortality involving adult human organs and tissues after whole body gamma ray exposures. This table summarizes the 1% incidence estimates for morbidity, derived from publications which utilize mathematical projections of dose-response data.
ICRP publication 103, pp168, Table A.3.4, 2007
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12. Deterministic effects
Projected threshold estimates of the acute absorbed dose for 1% mortality after whole body gamma ray exposures
Exposed population
Organ/Tissue
Time to develop effect
Absorbed dose (Gy)
Bone marrow syndrome
without medical care
Bone marrow
30-60 days
〜 1
with good medical care
2-3
Gastro-intestinal syndrome
Small intestine
6-9 days
〜 6
> 6
Pneumonitis
Lung
1-7 months 6
This table summarises the 1% incidence estimates for mortility, derived from publications which utilise mathematical projections of dose-response data.
【肺炎】
ICRP publication 103, pp168, Table A.3.4, 2007
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13. Stochastic effects
Detriment-adjusted nominal risk coefficients after exposure to radiation at low dose rate
Exposed population
Cancer
Heritable effects
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
【遺伝的影響】
ICRP publication 103, pp53, Table 1, 2007
Nominal risk coefficient is sex- and age at exposure-averaged lifetime risk estimates for a representative population. Recent calculation of coefficients for cancer and genetic effects, that is called as heritable effects here, are shown in this table.
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14. Risk Estimate for Cancers (Stochastic Effect)
Actual
measurement
Incidence of
cancer
Extrapolation
Linear Non-Threshold assumption
0.5%
Spontaneous
occurrence
Longitudinal studies for the victims of atomic bomb survivors have shown that at doses between 200 mSv and 3 Sv, the incidence of cancer increases linearly with radiation dose.
However, no one knows about the biological effects at doses below 100 or 200 mSv.
In order to estimate the risk for radiation exposure for the purpose of radiation protection, extrapolation from high dose to low dose has been used based on linear non-threshold hypothesis (LNT). According to this extrapolation, the incidence of cancers in the whole body exposure to 100 mSv is 0.5%.
However, epidemiological surveys have detected no difference in cancer incidence in various geographic regions, where the dose of natural irradiation varies from 2 to 10 mSv per a year.
Therefore, most experts believe that there is almost no biological effect of radiation exposure to dose of 10 mSv or less.
100 mSv
200 mSv
3 Sv
Radiation exposure
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15. 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
The next classification I will explain is “deterministic effects” and “stochastic effects”.
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16. Somatic Effects Genetic Effects
Effects of radiation limited to the exposed individual, as distinguished from genetic effects, that may also affect subsequent unexposed generations.
Genetic Effects
The radiation induced change in the DNA of germ cells resulting in the passing of the altered genetic information to future generations.
Somatic effects are the radiation injury limited to the exposed individual, primarily caused by the DNA damage on somatic cells. When the radiation induces change in the DNA of germ cells, the altered genetic information will be passed to future generations. That is called as genetic effects.
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17. External Exposures vs. Internal Exposures External exposure
Inhalation
Trough the skin
Ingestion
The next topic is two types of exposure to radiations.
When handling sealed radiation sources or operating radiation generators that do not produce radioisotopes, only external exposure need to be considered.
When handling unsealed radioisotopes emitting low-energy beta rays or alpha rays, internal exposure should be considered.
In the case of external exposure, strongly penetrating radiation, such as gamma rays or neutrons, is the main concern.
In contrast, with internal exposure, radiation with low penetration power, such as alpha and beta rays, are the principal problem, because the most of the energy is absorbed within the human body.
Radioisotopes taken into the body by inhalation or by ingestion are either excreted from the body mainly in urine and feces,
or remain in the body emitting radiation until they completely decay.
External exposure
Internal exposure
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18. Protecting Against External Exposure
As near to the radiation
source as possible
3 principles
Shield radiation sources.
Shielding
Shield
Stay as far away as possible.
Distance
Dose rate = K/ R2
K: constant
R: distance
During an experiment, you should protect yourselves against external exposure and internal exposure.
Measures for protection against external exposure should focus on the three principles: shielding, distance and time.
Dose rate in any workplace should be reduced by shielding radiation sources with lead, iron or concrete for γ rays, and plastic or water for neutrons.
Specific measures vary according to the type and energy of radiation. Shielding can generally be done easier and more economically as near to the radiation source as possible.
It is important to work as far as possible from the radiation source.
If the radiation source is a point source, the dose rate is in inverse proportion to the square of the distance.
By shortening exposure time, the exposure can be reduced.
Radiation workers should review operational procedures in advance, and work efficiently.
Time
Keep exposure time short !
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19. Prohibited Matters Eating or drinking Smoking Wearing make-up 19
In order to prevent radioisotopes from entering the body, these 3 matters are prohibited when you deal with radioisotopes, eating or drinking, smoking and wearing make-up.
Smoking
Wearing make-up
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20. Radiation-Related Quantities and Units
: Gray (Gy)
Absorbed Dose
- 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
In the last several slides, I will explain radiation-related quantities and units, and their usage in the field of radiation protection.
The first slide shows radiation-related quantities and units.
As a result of interaction between radiation and material, the energy absorbed per unit mass of the material is called absorbed dose.
The absorbed dose is a fundamental dosimetric quantity. Gray is the physical unit.
And the absorbed dose can be considered regardless of the kind of radiation or the kind of material.
One gray means that one joule of energy is absorbed per 1 kg of the material.
But, the problem is that absorbed dose does not reflect the degree of biological effects.
Even when the absorbed dose is the same, the degree of biological effects will differ depending on the kind and energy of the radiation.
To solve this problem, “equivalent dose” and “effective dose” were created to calculate the risk of irradiation to the human body.
The unit is Sievert in the both doses.
Equivalent Dose
: Sievert (Sv)
Effective Dose
: Sievert (Sv)
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21. 2. Linear Energy Transfer (LET) Linear Energy Transfer
(keV/mm) 【dE/dx (MeV/cm)】 P+ e-
Ionization
radiation
Low LET
radiations
(X, γ, β)
High LET
radiations
(α, neutron)
Densely ionizing
Sparsely ionizing
The energy transferred per given distance of track
The second factor that relates to biological effects is “Linear Energy Transfer”.
Radiations cause the ionization or excitation of the atoms when it pass through the human body.
The energy that transfers per given distance of track is defined as “Linear Energy Transfer ” or “LET”.
X rays, γ rays and β rays are classified into “low LET radiations”.
These radiations generate sparse ionization in the human body, and have less biological effect.
In contrast, α rays and neutron radiations are classified into “high LET radiations”.
These radiations ionize atoms densely, and cause more biological effect than “low LET radiations”. ＝
Less biological effect
More biological effect
Linear Energy Transfer
(LET)
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22. DNA is the Target of Radiations
Indirect action
Ionizing
OH.
H2O P+ e-
Low LET radiations
　(X, γ, β)
(free radical)
Direct action
Ionizing
Radiation affects any of the cellular components such as protein, lipid and DNA.
However, the main target is DNA.
Low LET radiations such as X rays, γ rays and β rays introduce damage on DNA via formation of free radical, so this is called indirect action.
In contrast, high LET radiations such as α rays and neutron radiations introduce damage directly on DNA. This is called direct action.
High LET radiations cause severer damage on DNA than low LET radiations. P+ e-
High LET radiations
(α, neutron)
2nm
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23. Equivalent Dose & Effective Dose
Equivalent Dose (HT )
: Sievert (Sv)
･ a measure of biological effects on a particular tissues or organs
･ HT = ∑wR ・DT, R R
wR ：Radiation weighting factor
DT, R　：Mean absorbed dose for a tissue or organ (Gy)
Radiation weighting factor (wR)
Radiation Weighting Factor
γ rays & Ｘrays
Beta rays
Proton
α rays, fission fragments, heavy ion　
Neutrons Continuous function
of the energy
Equivalent dose is a measure of biological effects of radiation on tissues or organs in the human body.
The relationship between equivalent dose and absorbed dose in a particular tissue or organ is described by the formula shown here.
The radiation weighting factor assumes that the degree of biological effect differs depending on the linear energy transfer of radiation.
For example, a radiation weighting factor of 1 is used for γ rays, X rays and beta rays. A radiation weighting factor 20 is used for α rays.
When the human body is exposed to radiation, the incidence of fatal cancer or severe genetic effect depends on the kind of tissues or organs.
In order to assess the total of such effects throughout the body, effective dose is used.
(ICRP 2007)
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24. Equivalent Dose & Effective Dose
Effective Dose (E)
: Sievert (Sv)
Stochastic effects
･ a measure of biological effects throughout the body (cancers or genetic effects) ･
E = ∑wT・HT = ∑wT・∑wR ・DT, R T R
Tissue weighting factors
Tissue/Organ Weighting factor
Red bone marrow 0.12
Colon
Lung 0.12
Stomach 0.12
Breast 0.12
Gonads 0.08
Bladder 0.04
Esophagus 0.04
Liver 0.04
Thyroid 0.04
Bone 0.01
Brain 0.01
Salivary gland
Skin 0.01
Others 　　
HT　 : Equivalent dose for tissues and
organs
wT： Weighting factor for organs or tissues
Annual average dose per person
Doctors mSv
Nurse mSv
Radiotherapy technicians mSv
Those engaged in research mSv
Nuclear power plant worker 1.3 mSv
Effective dose is a measure of biological effects of radiation throughout the human body.
To get the effective dose, tissue equivalent doses multiplied by tissue weighting factors are summed up for each type of exposed tissues and organs throughout the body.
This table shows average exposure dose per person in various occupations.
As can be seen, radiation exposure is relatively less in researchers than in other occupations.
Use radiations appropriately in research field, and radiation exposure will be minimum.
大学等放射線施設協議会
(ICRP 2007) 24

25. * * * Effective Dose Limits and Tissue Equivalent Dose Limits
for Radiation Workers (including Researchers)
Japanese law
Effective dose limit
Men mSv/year; 100 mSv/5years
(RIKEN: 20 mSv/year)
Women mSv/3 months
Pregnant women 1 mSv as internal exposure
Tissue equivalent dose limit
1) Lens of the eye mSv/year
2) Skin mSv/year
3) Abdomen of pregnant women 2 mSv *
For radiation workers, radiation exposure is controlled so as not to create a radiation hazard.
Japanese law regulates the dose of radiation exposure for radiation workers as shown here.
Effective dose is limited to 50 mSv/year and 100 mSv/5 years.
For women, effective dose is limited to 5 mSv/3 months.
Tissue equivalent dose is limited to 150 mSv/year for the lens of the eye, and 500 mSv/year for the skin.
If you confirm pregnancy, please let administration office knows, and dose limitation will be changed. *
From the confirmation of pregnancy to delivery *
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26. Concerning Prevention of Radiation Hazards
Laws and Ordinances
Concerning Prevention of Radiation Hazards
放射線障害防止法および関連規則
ISBN
東京都文京区弥生 東京大学アイソトープ総合センター内 電話: 　Fax:
大学等放射線施設協議会 26

27. 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.

28. 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<1MeV)
[concerned authority : Ministry of Health, Labor and Welfare]

29. Radioisotopes to be controlled
Laws concerning Prevention of Radiation Hazards due to Radioisotopes, etc.
Radioisotopes to be controlled
concentration + activity > exemption level
(IAEA BSS Safety Series No. 115, 1996)
Accelerators to be controlled
dose rate at 10cm from surface >0.6 mSv/h

30. Exemption level of radioisotopes
Radionuclides
Activity
(MBq)
Concentration
(Bq/g)
H-3
1,000
1,000,000
S-35
100
100,000
P-32
0.1
Ni-63
I-125 1
Co-60 10
Cs-137
0.01
Sr-90
放射性同位元素の規制下限数量の例
大学等放射線施設協議会

31. Dose Rate Limits at a Facility
radiation controlled area
boundary of
boundary of
institute
beam
<1 mSv/w
<1.3 mSv/3M
<250 mSv/3M
shield
<25 mSv/h
(40 h/w, if no access controll)
<2.6 mSv/h
(500 h/3M)
<0.11 mSv/h
(2184=24×91 h/3M)
interlock

32. Nishina School 2010/10/12
Rules at RIBF Facility

33. In 1st class area, wear a work uniform or lab coat.
How to enter and exit the 1st class radiation controlled area.
In 1st class area, wear a work uniform or lab coat.
They are placed on the shelf at the entrance.
Return the used ones in the plastic laundry box next to the exit.
Do not throw in a uniform that is still clean during the experiment, to avoid unnecessary laundry.
use a uniform on a hanger for temporary work.
uniform for
temporary
work
work uniform
plastic laundry box

34. ② ① ③ ④ Do not wear the shoes while on the blue mat !! display scanner
Take off your shoes
and put them in the
shoe cupboard.
intercom
Scan your barcode. ③ ④
Do not wear the shoes
while on the blue mat !!
Take safety shoes of
proper size.
Put on them
off the blue mat.

35. Exiting from the radiation controlled area
Wash your hands.

36. Contamination monitoring by hand-foot-clothes monitor.
(2) Test contamination by hand-foot monitor.
Contamination monitoring by hand-foot-clothes monitor.
When warning alarm goes off signaling contamination:
Try the monitor again.
Wash your hands once more and try monitor again.
If feet or clothes are contaminated, or washing your hands many times can not remove contamination, use the nearest phone to contact staff in the radiation control room or call the emergency number on the bulletin board.
（Stay still as much as possible to prevent further contamination.）
(1) Scan your barcode.
Place hands inside the monitor and
push downward.
Wait 10 seconds for monitoring.
(3) Use the clothes monitor.

37. All articles taken out from the radiation controlled area must be monitored for contamination.
It shows “Contamination” in red
and alarm goes off.
Write down the test result.
When using the cart,
monitor the cart wheels.
When the pointer indicates over 100cpm,
you cannot take the article out.
Consult with radiation control staff.

38. At the end, return safety shoes, and scan your barcode.

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

40. Evacuation route.(4) 3rd floor basement of RIBF Experiment bldg.

41. Enjoy your experiment.