RADIATION RE-EDUCATION MATERIALS THE UNIV. OF TOKYO DOC No. 42 (2024)
1. Peaceful Use of Radiation and SDGs

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2. Radiation Risk for Diseases of the Circulatory System3

3. Types and Roles of Safety Systems in Accelerator Facilities

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4. The Approach to Management in Small Quantity Nuclear Fuel Facilities

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5. Characteristics of X-rays and Radiation Safety of X-ray Generators

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Edited by Division for Environment, Health and Safety1

Peaceful Use of Radiation and SDGs

Sustainable Development Goals (SDGs) are development goals adopted in the UN
Summit which was held in September 2015. Recently, SDGs are becoming more popularamong young generations. As you know, since the Japanese Government promotes
actions to achieve SDGs, we have many opportunities to recognize SDGs as “my own
issue” through elementary school, junior high school and universities as well as companies
and local government. The year 2023, when I am writing this article, corresponds to just in
the middle year between the adopted year (2015) and the goal year (2030) of SDGs. This
is why, SDG Summit 2023 attracts attention to review the perspective of SDGs, which isheld at UN Headquarter for the first time in 4 years.
Although SDGs are thus getting popular and well recognized in public, some people
don’t get it when they hear SDGs are related to peaceful use of radiation. This article isto show you the International Atomic Energy Agency (IAEA)’s activities aiming to achieve
SDG goals through use of radiation/nuclear power, since I have been engaged in the IAEA
until recently.
Even in Japan, we often hear the IAEA’s activities such as inspections to theZaporizhzhia Nuclear Power Plant, IAEA Comprehensive Report on the Safety Review of
the ALPS-Treated Water at the Fukushima Daiichi Nuclear Power Station. Based on its
professional expertise, the IAEA develops many activities not only in the field of nuclear
power but also in the other fields.
I have been engaged in the activities of the IAEA Technical Cooperation Department
for 3 years from 2020. And I had an opportunity to recognize the IAEA’s wide range ofactivities in no time. As 2020 was the start year of COVID-19 pandemic, the IAEA Director
General (DG), Rafael Mariano Grossi, immediately established the Zoonotic Disease
Integrated Action (ZODIAC) initiative to help countries prevent pandemics caused byviruses that originate in animals and can be transmitted to humans. This initiative has
provided Real Time RT-PCR which is a nuclear-derived method for detecting the presenceof COVID-19 virus. I was amazed by the IAEA’s quick action and extensive field ofactivities.
As the IAEA is placed as the specialized agency in the nuclear field within the United
Nations family, it facilitates support to the Member States, paying attention to achievementof 2030 Agenda, one of the UN action plans. While SDGs are composed of 17 goals and
169 targets, the IAEA advocates direct contribution to 9 out of 17 SDG goals (SDG 2, 3, 6,
7, 9, 13, 14, 15 and 17), using Nuclear Science and Technology (NST). Let’s have a lookat the IAEA’s international cooperation for each SDG below.
SDG2― Zero Hunger
The IAEA contributes to improvement of food security and agriculture, collaborating with
the Food and Agriculture Organization of the United Nations (FAO). For example, the IAEA
assists the Member States to introduce the Sterile Insect Techniques (SIT) to protect crops
by releasing sterilized mass-reared males that cannot produce offspring, which leads toreduction the number of insect pests. Furthermore, the IAEA helps the Member States
to breed new plant varieties by irradiation, which are drought tolerant and/or disease
resistant.
SDG3―Good Health and Well-being
To reduce deaths from noncommunicable diseases such as cancer, the IAEA helps theMember States strengthen nuclear medicine, radiation oncology and radiology facilities, aswell as provide education and training to medical staff. Above all, under the “Rays of Hope”
initiative, advocated by the DG in 2022, the IAEA helps low- and middle-income countries-1-mostly in Africa strengthen radiation safety and regulatory infrastructure to increase accessto cancer care, as well as provide guidance, technical advice, training and equipment.
SDG13―Climate Action
Nuclear technologies play a key role in climate change mitigation. Since nuclear power
does not generate carbon dioxide during operation, which is regarded as clean energy. The
IAEA works to increase awareness of the role of nuclear power in reducing greenhousegas emissions and in the other applications of nuclear energy such as hydrogenproduction, and assists countries to adapt to the consequences of climate change throughthe development of crops with increased resilience.
SDG14―Life below Ocean
To sustainably manage and protect oceans, in turn, support coastal communities, the
IAEA assists marine monitoring using nuclear and isotopic techniques, and promotes
technical cooperation and better understanding so that the Member States can use
nuclear-derived technologies to tackle with the ocean phenomena such as ocean
acidification, harmful algal blooms and microplastic pollution. In particular, the IAEA Marine
Environmental Laboratories in Monaco help many countries use isotopic techniquessuch as marine plastic tracing and impact assessment of marine lives to address plastic
pollution in the oceans, which is mainly through the NUclear TEChnologies for Controlling
Plastic Pollution (NUTEC Plastics) initiative, advocated by the DG in 2021.1
SDG15―Life on Land
Desertification, degrading land and eroding soils can jeopardize agriculture andlivelihoods in developing countries. The IAEA supports the Member States by accurate
assessment of soil erosion using isotope techniques, providing tools to reverse landdegradation and restore soils.
In this way, the IAEA’s field of activities covers not only nuclear power but also otherfields related to atoms for peace and development such as food, health care, soil andmarine environment. Although I was not so conscious of such a broader field of activities
when I was in charge of radiation in Japan, the experience in the IAEA has made me
conscious of peaceful use of radiation/nuclear power. I hope this article provides you theopportunity to recognize SDGs as “your own issue”.
References
https://www.mofa.go.jp/mofaj/gaiko/oda/sdgs/pdf/sdgs_gaiyou_202305.pdf
https://www.iaea.org/sites/default/files/22/08/iaea_and_the_sdgs.pdf
https://www.iaea.org/bulletin/covid-19-real-time-rt-pcr-testing-explained
https://www.iaea.org/services/zodiac
https://www.iaea.org/services/key-programmes/nutec-plastics
https://www.iaea.org/services/rays-of-hopeAssistant Manager, Japan Atomic Energy Agency(Former) Consultant, Division for Asia and the Pacific, Department ofTechnical Cooperation, International Atomic Energy Agency (IAEA)
Koichi WATANABE
Re-Education Theme: Topic

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This initiative also assists the Member States in plastic waste recycling by radiation technology as
well as marine plastic monitoring.
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Radiation Risk for Diseases of the Circulatory System

Recommendations by the International Commission on Radiological Protection (ICRP)
have been the basis of national radiation protection regulations and standards implemented
in Japan and many other countries. ICRP reviews the radiation protection system, taking
into account scientific developments and social situations. This paper briefly explains why
ICRP came to recommend a threshold dose for diseases of the circulatory system (DCS)
in 2011, significance of the recommendation, and recent relevant developments.
ICRP has always considered, since the 1950s, that the ocular lens, bone marrow andgonads represent among the most radiosensitive tissues, whereas ICRP had considered,by the 1980s, that the circulatory system is not highly radiosensitive because radiation
effects occur after radiotherapy at fractionated doses of >40 Gy. However, in the 1990s,
the excess risk of DCS mortality at ≥2 Gy was reported in Japanese atomic bomb survivors[1], and therefore ICRP put DCS risks on the radar. A paper came out in 2010 that reported
the excess risk of DCS mortality at ≥0.5 Gy [2], leading ICRP to classify DCS as tissue
reactions and recommend a threshold dose, in 2011 for the first time [3]. Non-cancer effects
that are assumed to exhibit threshold-type dose-response relationships and are considered
attributable to injury in populations of cells are referred to as tissue reactions (called“deterministic effects” in the 2007 general recommendations [4] or earlier), and equivalentdose limits have been recommended to prevent its occurrence. ICRP recommended 0.5 Gy
as a threshold for DCS, assuming that 1% of exposed individuals develop cardiovascularand cerebrovascular diseases, respectively, >10 years after exposure of the heart and thebrain to 0.5 Gy independent of the rate of dose delivery. However, this recommendation
was intended to serve as a precaution to medical practitioners, and dose limits were notrecommended: this was because effects at low dose, mechanistic underpinnings andtarget organs remain uncertain.
ICRP justified 0.5 Gy as the 1% level dose, given the meta-analysis excess relative risk
per unit absorbed dose (mERR/Gy) of 0.10 (95% confidence intervals (CI): 0.07, 0.13) for
DCS incidence that was based on the four studies and described in the 2010 report [5], andnatural baseline incidence of 30–50%. It can be considered still valid, because the paper
published in 2023 reported mERR/Gy of 0.09 (95% CI: 0.05, 0.13) for DCS incidence. On
the other hand, regarding DCS mortality risk, the 2010 report [5] described mERR/Gy of 0.08
(95% CI: 0.04, 0.12) based on the 8 studies that is similar to mERR/Gy for DCS incidence,but the 2023 paper [6] described mERR/Gy of 0.20 (95% CI: 0.13, 0.26) based on the 54
studies that doubled mERR/Gy for DCS incidence. Save a single study [7], cohort studies
with long follow-up have not found significant dose thresholds, and it also remains unclear
whether injury in populations of cells underlie DCS. This necessitates further discussions
as to whether classification of DCS as tissue reactions and its threshold of 0.5 Gy aresound, and how we consider differences in DCS risks between incidence and mortality.
ICRP has considered that there is no dose protraction effect for DCS (i.e., dose
protraction does not change the magnitude of effects) [3]. However, the meta-analysis of
the 93 epidemiological studies showed that mERR/Gy in descending order of low dose
rate exposure > acute exposure > fractionated exposure [6], and the rodent study has foundthe greater magnitude of radiation damage to the aorta in descending order of exposurein 25 fractions > acute exposure > exposure in 100 fractions >> chronic exposure [8]: thesestudies suggest that dose protraction effects are not a simple function of dose rate or thenumber of fractions. Taken together, it has been shown that ERR/Gy for DCS at lower dose-3-

is greater than that at higher dose [9,10]. This thence necessitates further discussions as to
how we consider the potential difference in effects with dose and dose rate.
The threshold doses that ICRP recommended in 2011 were 0.5 Gy for both of thelens and the circulatory system [3], so the circulatory system can be considered as highly
radiosensitive as the lens. However, DCS pathophysiology and cells that populate thecirculatory system are diverse, and mechanisms are uncertain. Increased radiation risks forischemic heart disease have been observed in various western cohorts, and atherogenesis
caused by chronic vascular inflammation has been proposed as a potential mechanism[11]. Hypertensive diseases, however, dominate in atomic bomb survivors, and mechanisms
behind DCS other than ischemic heart disease hence need to be studied. Proposed
candidate target organs include the heart, large blood vessels (e.g., aorta, carotid), kidneys
and pancreas, but consensus has yet to be reached [11].
There are ongoing clinical trials of radiotherapy for ventricular tachycardia (a lifethreatening arrhythmia), whilst elevated radiation risk of arrhythmia has been reported
in the cohorts of radiotherapy patients and radiation workers. As such, radiation may
represent a double-edged sword not merely for cancer but also for DCS, so thatjustification of radiation exposure and optimization of protection would be required for thecirculatory system [12,13].
ICRP aims to publish the next set of general recommendations in the 2030s thatsupersede the 2007 general recommendations [4], and has initiated relevant discussions.
Concerning DCS, Task Groups 111, 119 and 123, respectively, are discussing issues
in relation to inter-individual differences of radiation sensitivity, implications of scientificevidence for radiation protection, and radiation effect classification. These outcomes are
considered to serve as building blocks for the next set of general recommendations, andaccordingly it is important to keep a close watch on ongoing discussions.
References[1] Shimizu. Y., et al. (1992) Studies of the mortality of A-bomb survivors. 9. Mortality, 1950–1985:
Part 3. Noncancer mortality based on the revised doses (DS86). Radiat. Res., 130(2), 249–
66.
[2] Shimizu, Y., et al. (2010) Radiation exposure and circulatory disease risk: Hiroshima and Nagasaki atomic bomb survivor data, 1950–2003. BMJ, 340, b5349.
[3] ICRP. (2012) ICRP Publication 118. ICRP statement on tissue reactions and early and late effects of radiation in normal tissues and organs – threshold doses for tissue reactions in a radiation protection context. Ann. ICRP, 41(1–2), 1–322.
[4] ICRP. (2007) ICRP publication 103. The 2007 Recommendations of the International Commission on Radiological Protection. Ann. ICRP, 37(2–4), 1–332.
[5] AGIR. Circulatory disease risk. HPA, RCE-16. Chilton, UK, 2010.
[6] Little, M.P., et al. (2023) Ionising radiation and cardiovascular disease: systematic review andmeta-analysis. BMJ, 380, e072924.
[7] Takahashi, I., et al. (2012) A prospective follow-up study of the association of radiation exposure with fatal and non-fatal stroke among atomic bomb survivors in Hiroshima and Nagasaki(1980–2003). BMJ Open, 2(1), e000654.
[8] Hamada, N., et al. (2024) Sparing and enhancing dose protraction effects for radiation damage
to the aorta of wild-type mice. Int. J. Radiat. Biol., 100(1), 37-45.
[9] Little M.P., et al. (2020) Lifetime mortality risk from cancer and circulatory disease predictedfrom the Japanese atomic bomb survivor Life Span Study data taking account of dose measurement error. Radiat. Res., 194(3), 259–76.
-4-[10] Little, M.P., Hamada, N. (2022) Low-dose extrapolation factors implied by mortality and incidence data from the Japanese atomic bomb survivor Life Span Study data. Radiat. Res.,
198(6), 582–89.
[11] Tapio, S., et al. (2021) Ionizing radiation-induced circulatory and metabolic diseases. Environ.
Int., 146, 106235.
[12] Hamada, N. (2023) Noncancer effects of ionizing radiation exposure on the eye, the circulatory
system and beyond: developments made since the 2011 ICRP statement on tissue reactions.
Radiat. Res., 200(2), 188–216.
[13] Thariat, J., et al. (2024) Radiotherapy for non-cancer diseases: benefits and long-term risks.
Int. J. Radiat. Biol., 100, in press.

Senior Research Scientist, Central Research Institute of Electric Power Industry (CRIEPI)
Nobuyuki HAMADA, R.T., Ph.D.
Re-education Theme: Human Body Effects

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Types and Roles of Safety Systems in Accelerator Facilities

The radiation generator, i.e., the particle accelerator, was invented in the first half ofthe 20th century for nuclear physics research and has progressed significantly up to thepresent. Today, accelerators are utilized not only in nuclear physics but also across various
research fields, as well as medical and industrial applications. Before using accelerators
regulated by Acts and Regulations 1, specific permission from the Nuclear Regulation
Authority is required. Therefore, accelerator facilities must adhere to strict standards forradiation safety.
The safety systems in accelerator facilities vary based on the type, energy, and usageof the radiation. However, the primary goal of radiation safety management is to prevent
hazards and ensure public safety, similar to facilities handling radioisotopes. This article
introduces some safety devices commonly used in accelerator facilities for radiation safety.
Interlock System -- Automatic Display Device
The law mandates the installation of interlock systems to prevent unintentional entry into
the accelerator room. Additionally, automatic display devices at the entrance must indicate
when the accelerator is in use.
Usually, accelerators are equipped with interlocks that allow the beam to be generated
only when several conditions are met. Interlocks serve not only for radiation safety control
but also to safeguard the entire accelerator from failure. For example, they ensure a safe
shutdown of the accelerator in the event of abnormal situations caused by operational
errors or malfunctions in certain equipment.
Access Control Device -- Confinement Prevention Device
The access control device for the radiation-controlled area is linked to the interlock
system. No one can enter the room during a beam being generated and a beam cannot be
generated during someone entry into the accelerator room. If someone ever gets trapped,
emergency escape is possible from the accelerator room. Many facilities have emergency
stop buttons and safety switches inside the room.
Radiation Monitor
Accelerator facilities are designed so that the radiation generated by the accelerator
does not escape from the controlled area. Even after operation, targets, slits, and beam
dumps may become radioactive. In high-energy accelerator facilities, radioactivation ofequipment, walls, air, and cooling water can be a serious concern. Radiation monitors are
installed to measure the dose, reducing the risk of radiation exposure and preventing therelease of activated materials externally. This is often one of the conditions of the interlock
system.

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Radiation generator as used in the Acts and Regulations means equipment which generates radiation by accelerating charged particles such as cyclotrons, synchrotrons, etc., which is prescribedin Cabinet Order (excluding those whose maximum dose equivalent rate at the position 10 cm
away from the surface is not more than 600 nSv per hour).
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Similar to facilities handling radioisotopes, radiation workers must wear personal
dosimeters when entering controlled areas in accelerator facilities. Additionally, otherradiation measuring devices may be used, including hand-foot-cloth monitors to measureradioactive contamination on personnel leaving controlled areas and alarm meters toprevent unplanned radiation exposure.
Inspection and calibration of radiation measuring instruments were mandatory in 2023.
However, inspections of other safety devices are also crucial. Although some safety
devices are seldom used in daily accelerator operation, periodic inspections are necessary
to ensure proper functionality in emergencies.
These safety devices work effectively only when used correctly by radiation workers.
During facility training sessions, each worker should carefully go through the safety
management system. It is also important to anticipate potential risks associated with tasks
and understand how to respond to issues.
Up to this point, my focus has been on radiation safety systems. However, accidents
related to radiation are exceedingly rare in accelerator facilities; other types of accidents
are much more common.
The University Museum, the University of Tokyo, has two Van de Graaff accelerators: a
5MV tandem accelerator at MALT on the Asano campus and a 500kV tandem accelerator
at the main museum on the Hongo campus. The 5MV tandem accelerator at MALT is aradiation generator regulated by the Act and Regulations and is located in the controlledarea surrounded by thick concrete and steel shielding doors 1. In contrast, the 500kV
tandem accelerator at the main museum is exempt from the Act and Regulations due to its
low radiation dose and energy. As a result, it is located in a glass-walled exhibition room,
not in the controlled area, allowing visitors to easily observe its operation. Although the
500 kV tandem accelerator doesn’t pose an inherent danger as a radiation generator, both
accelerators have ion sources with high voltages and electromagnets with high currents,
which can be extremely hazardous if touched accidentally. Moreover, the beamlines,
equipment, and racks are heavy and require careful handling. Furthermore, there are
narrow areas, steps, and projections around the accelerators that may also have a risk of
injury.
To use accelerators safely, just like any other experimental equipment, it’s important tounderstand potential hazards fully. Before operating an accelerator, read the manual andinstruction carefully and receive proper guidance from experts familiar with the equipment.

The University Museum
Hironori TOKUYAMA
Re-education Theme: Safety Handling, Raws and Ordinances

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4

The Approach to Management in Small Quantity
Nuclear Fuel Facilities

Among radioactive substances, materials such as uranium, thorium, and plutonium,
which release high energy in the process of nuclear fission, are defined as nuclear fuelmaterials by the Nuclear Reactor Regulation Act. Moreover, because nuclear fuel materials
can also be used in the production of nuclear weapons, the International Atomic Energy
Agency (IAEA) carries out management of these materials internationally. Therefore,
these materials are also called “internationally controlled materials” and together withrelated equipment are defined as international regulated items. To use these nuclear fuelmaterials, permission (or approval in the case of national university corporations) must be
obtained from the Nuclear Regulation Authority.
Facilities that use nuclear fuel materials are classified as J facilities or K facilities basedon the types and quantities of nuclear fuel materials that they can use. As shown in Table 1,
facilities that use only a small amount of nuclear fuel materials are classified as K facilities,
while others are classified as J facilities. As of 2023, the University of Tokyo has 2 J and
14 K facilities. Natural uranium mentioned in Table 1 refers to uranium that is naturally
occurring, with a U-235 isotope composition of 0.720%. In contrast, depleted uranium has
a lower U-235 isotope abundance, around 0.2%, compared to natural uranium.
This article explains the handling of nuclear fuel materials in K facilities, which arefacilities that use only a small amount of nuclear fuel materials.
To ensure proper management of nuclear fuel materials, the Nuclear Reactor Regulation
Act requires the creation of accounting provisions in advance. Nuclear materials
accountancy administrator and appropriate persons should make sure that these provisions
are readily available for review and ensure that their contents are communicated to nuclear
fuel materials users.
Accounting provisions mainly include the following:
•
•
•
•
•

Position and role of the nuclear materials accountancy administrator.
Location of the nuclear fuel Material Balance Area (MBA) where nuclear fuelmaterials can be used.
Records of receipts, shipments, and disposals.
Inventory.
Reporting to the Nuclear Regulation Authority.

In K facilities, it is necessary to submit nuclear fuel materials management report to the
Nuclear Regulation Authority twice a year (1st half from January to June, 2nd half from Julyto December). This report should detail the inventory changes during the reporting period,
which means how much material was received or shipped during that time.
Points to note when using nuclear fuel materials:
Workers should:• Workers should record the quantity to decimal places (no rounding) each time theyuse, receive, or ship materials.
• Monthly, an inventory of the quantity by compound and supplier country should berecorded.
Table 1 Nuclear fuel materials that can be used in K facilities.
Uranium (U)Thorium (Th)Natural uranium
Depleted uranium
Lower than 300 g.
Lower than 900 g.

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•

Safe handling and disposal methods should follow the instructions of the MBA’s
management (since there is no disposal mechanism for nuclear fuel materials, theymust be stored within the department).
Consult with the nuclear materials accountancy administrator before receiving or
shipping materials to other departments or external entities (other MBAs). When
receiving, submit a nuclear fuel material transfer report or a copy of it in accordancewith the MBA’s management instructions.

Nuclear materials accountancy administrators should:• Conduct monthly inventory for each compound and supplier country, as stated in
Accounting Provisions Article 8. If workers conduct the inventory according to theMBA’s policy, the nuclear materials accountancy administrator should confirm thecompletion.
• A nuclear fuel material transfer report should be created and exchanged when
receiving or shipping materials between K and J facilities.
• Create a nuclear fuel material management report in July and January and submit itto the Division for Environment, Health, and Safety.
• Consult with the Division for Environment, Health and Safety before making changes
to accounting provisions or the nuclear fuel materials used.
Points to note when receiving and shipping materials include:
When receiving nuclear fuel materials, ensure that the type, supplier country, andquantity of the total amount of receiving materials with existing inventory do not exceed theamount approved by the Nuclear Regulation Authority.
When moving nuclear fuel materials between K facilities, it is not necessary to exchange
nuclear fuel material transfer reports, it needs to confirm the total amount of receiving
nuclear fuel materials plus existing inventory does not exceed the amount indicated inTable 1. When moving nuclear fuel materials between K and J facilities, it is necessary
to exchange nuclear fuel material transfer reports. Normally, the format of the J facility’s
nuclear fuel material transfer report is used for creating these reports. However, theDivision for Environmental, Health, and Safety can provide templates if needed.
Workers using nuclear fuel materials should not receive them without consulting thenuclear materials accountancy administrator in advance. Similarly, for shipment, confirm
with the nuclear materials accountancy administrator before proceeding.
Finally, when using nuclear fuel materials, it is essential to adhere to establishedrules and manage the materials according to accounting provisions, including keeping
accurate records in the inventory. This responsibility applies not only to nuclear materials
accountancy administrators but also to workers of nuclear fuel materials.

Division for Environment, Health and Safety
Rie MIZUNO
Re-education Theme: Nuclear Fuel Materials, Safety Handling, Laws and Audinances

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Characteristics of X-rays and Radiation Safety of
X-ray Generators

X-rays, a type of photon radiation, are produced in an X-ray generator by hitting anappropriate material with high-speed accelerated electrons. X-rays have higher energy
than ultraviolet rays, so strong X-rays, like other radiation, can have effects on livingorganisms through the formation of radicals. Therefore, when X-rays are used for researchor other purposes, it is recommended that the workplace be monitored before, during,
and after the work to check the radiation situation. In addition, it is known that even when
periodic radiation measurements are considered “leak-free” by technical contractors,
leaks can be easily detected. It has also been noted that one day significant radiation was
inadvertently detected in a location that no one had imagined, and additional shielding was
installed. Do you know where and how much radiation is actually present when you use an
X-ray machine?
In recent years, the design of the X-ray generators available on the market has madethem much safer. On the other hand, no matter how good the technology, there can besafety hazards in areas that are not related to the technology. It is important to recognizethat there are not only “unintentional” accidents, where a user is too focused on something
and fails due to lack of awareness or poor judgment, but also “reckless” accidents, where
safety is sacrificed for the sake of work efficiency and results. University faculty andstaff have a duty to protect students. One of the characteristics of a university is that it
is a very special organization with a high degree of human mobility, and members whoare immature as researchers and professionals may be engaged in risky work. It will
also be important not to leave everything to safety devices and related systems, but tobe aware of their possible malfunctions and failures, and to systematically check theirfunctioning. Continued use of older equipment will require special care and attention. It
is important to pass on a culture of safety from one generation to the next and to shareproblematic cases horizontally. In addition to pre-work safety training, it can be effective
to actively demonstrate safety measures in daily activities, such as lab tours for visitors.
In accordance with IAEA safety requirement, your university has already implemented a“graduated approach” for the management of x-ray generators. This is a very well-designed
safety management method that is expected to become a standard in Japan in the future,and I hope that you will refer to the compact explanation in the FY2019 refresher material (tobe reprinted in FY2023) and use it for further environmental management related to x-ray
use.

Chief Senior Researcher, National Institute of Public Health
Ichiro YAMAGUCHI, M.D., Ph.D.
Re-education Theme: Safety Handling, X-rays- 10 -