Study Guide for Radiation Safety

October, 2022
Radiation Science Center
High Energy Accelerator Research Organization (KEK)Contents
1 Basic Rules for Radiation Protection‥ ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 1
2 Radiation-Safety System‥ ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 23 Personnel Exposure Control‥ ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 34 Radiation-Controlled Areas‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 65 Entering a Radiation-Controlled Area‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 7
6 Radiation-Generating Apparatus and Instructions concerning Radiation Work‥‥‥‥‥‥‥‥‥‥ 107 Radiation Work for Outside Workers‥ ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 12
8 Handling of Radioactive Materials‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 14
8.1

Handling and Loan of Sealed Radioisotopes

8.2

Handling of Radioactive Materials, such as Non-sealed Radioisotopes

9 Radiation Detectors‥ ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 16
10 Suspension, Return, and Termination of Radiation Work,and Radiation Work outside KEK‥ ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 17
11 Fire Emergency Response Procedures in the Radiation-Controlled Areas‥‥‥‥‥‥‥‥‥‥‥‥‥ 17
11.1 Fire Emergency Response Procedures
11.2 Fire extinguishing restricted area
11.3 Facilities and Rooms Assigned as Special and Fire extinguishing restricted area
11.4 Signs Indicating Fire extinguishing restricted area

Radioisotopes (RI) and radiation-generating apparatus (installations producing ionizing radiation,such as accelerators) may have the potential to cause risks of hazardous radiation exposure tohuman bodies during handling and operation. KEK has a set of rules concerning the radiation
protection system for radiation workers and the general public. This protection system satisfies therequirement that, during operation or handling, exposure of the staffs to radiation must be kept to areasonably achievable minimum, while considering various factors.
From a radiation-safety point of view, this brochure aims to provide essential information
concerning radiation protection. This information must be understood by staff members, students
and users from other organizations. They have to follow certain regulations during their work
involving radiation. The topics covered in the brochure include the radiation-safety control system,
criteria for exposure control, various procedures that must be fulfilled by radiation workers, and fire
emergency response procedures. For more details, please consult the Radiation-Control Office.

1 Basic Rules for Radiation Protection
There are seven radiation-controlled areas where accelerators and radioisotopes are handled.
Radiation work implies all work conducted in these areas. The only workers allowed to perform
work and experiments in these controlled areas are those who are registered as radiation workers,
have received education and training on radiation safety, and have been health-checked by a doctor
Before working in a radiation-controlled area, it is advisable for everyone to get acquainted with therules and standards concerning KEK radiation safety.
The risk of radiation exposure during radiation work greatly depends on the location in theradiation-controlled area. Radiation workers must know such information as admissible radiationlevel in their working area, which they need to understand to ensure radiation safety.
They must try to avoid or keep as low as possible any undue radiation exposure.
As a matter of fact, the achievement of radiation safety depends on individual personal
comprehension of radiation safety. Every individual working with accelerators or radioisotopes
must always be aware of the responsibility to protect both himself/ herself and other workers fromany radiation exposure arising from his/her work.

Enough Shielding

Long Distance

Short Working Time

Figure 1-1: Three principles for protection against external exposure.
In order to reduce external exposure during radiation work, it is recommended to be properly
shielded from radiation sources, to maintain sufficient distance from them as far as possible,
and to complete all work within a short time.
―1―Radiation source at KEK
At KEK, the main radiation is coming from high-energy accelerators of electrons (e-) and positrons(e+): 7 GeV-e-/4 GeV-e+ linear accelerator, 2.5 GeV-e- photon factory, SuperKEKB 4 GeV-e+/
7 GeV-e- collider, 6.5 GeV-e- PF-AR ring. In the daily radiation work at KEK, the radiation
environment is changing according to the operation conditions of the accelerator facilities. During
the operation, radiation workers and beam users are working in the experimental areas with different
radiation levels. In the electron facilities (photon factory, SuperKEKB), radiation level behind theshielding is quite negligible. After the operation stops, radiation workers can enter the beam-line
tunnels for maintenance of the beam lines where gamma-rays, emitted from radioactive accelerator
components, are responsible for most of the radiation.

2

Radiation-Safety System(1) The radiation-controlled area (Appendix 1) is divided into seven sections (Appendix 2). Eachsection has one appointed regional radiation-safety officer (belonging to the Radiation
Science Center), and one or more appointed regional radiation-safety liaison officers, who
belong to different institutes and facilities. They are representatives of each working area andfacility. The regional radiation-safety officer, in cooperation with the radiation-safety liaison
officer(s), carries out his duties to ensure radiation safety by monitoring the radiation andradioactivity levels in controlled areas in order to keep the safe working environment.
(2) The Directors-General appoints a radiation-generating installation supervisor for eachradiation-generating apparatus. Secondary beamlines, branching off from the main primarybeam-lines, and systems, which emit X-rays, like klystrons, are also controlled as radiationgenerating apparatus. While the Division or Group leaders are responsible for the maintenanceand management of their assigned apparatus, the radiation-generating apparatus supervisor
must operate the apparatus according to the license regarding the beam intensity and beamenergy. He must regularly inspect the safety equipment, such as any interlock systems, in orderto ensure safe operation. Naturally, any remodeling or renovation of the radiation-generating
apparatus without the permission by the Directors-General is forbidden.
(3) As shown in the scheme of the safety organization (Appendix 3), the KEK radiation-safetysystem is centralized. The Radiation-Safety Supervisor is in charge of observing theeffectiveness of the radiation safety system. If any problem is found, it is his duty to inform the
Directors-General to improve the system.
(4) The Radiation-Safety Committee discusses important items, such as the basic rules, various
criteria, and the installation or renovation of the facilities of the radiation-generating apparatus.
Afterwards, it makes recommendations to the Directors-General.

―2―(5) The names and telephones of the regional radiation-safety officers, radiation-safety liaison
officers and radiation-generating apparatus supervisors are listed on web page (https://rcwww.
kek.jp/user/top.html). Daily or emergency contacts, requests, and inquiries should be reported
to the Radiation-Control Office (TEL:3500), which is located at the south part of the
Radiation Science Center building.
Please feel free to send inquiries about any details concerning radiation safety to the RadiationControl Office.

3

Personal Exposure Control(1) The criteria concerning the annual dose limit for radiation workers and other persons have been
determined as listed in Table 1 (each year, beginning from the 1st of April; every three months,
starting from the 1st day of April, July, October, and January).
(2) According to the philosophy of the law regarding radiation exposure, the latter must be kept toa reasonably achievable minimum; also considering the international tendency for decreasingof the dose limit, working levels of radiation doses are employed in order to be controlled daily
and weekly (Table 2). In order to avoid over-exposure inside of the area of high radiation, suchas beam lines of accelerator facilities, it is recommended that each radiation worker must keep
the working level per day in mind.
(3) Personal dosimetry for radiation workers is performed as follows:• Personal monitoring of radiation doses is conducted at KEK using a personal dosimeter,
and the radiation dose is measured monthly. It is required that workers keep these assigned
dosimeters with them in any controlled area. Other personal dosimeters, such as a directreading alarm meter and a DIS dosimeter, must be carried in addition to the assigned
personal dosimeters, when working in a high-radiation area, such as the beam-line tunnels of
the proton synchrotron facilities, some high-dose areas in the Linac, and the SKEKB tunnel.
• Users are required to exchange monthly their personal dosimeters. Any used personal
dosimeter should be returned immediately after the end of the month period to theRadiation-Control Office through the group offices. If there is a delay in returning adosimeter, personal monitoring cannot be performed promptly, and evaluating the dose
becomes difficult.
• The results of personal monitoring are sent to individuals by the Radiation-Control Officethrough the leaders of the divisions, groups, and facilities. Please consider carefullythese results of personal monitoring to keep the exposure during radiation work as low as
possible.
―3―

Table 1: Exposure Control
Category
Radiation Worker

Item
Effective Dose:Man
Woman[1]Dose Limit
20 mSv/year
6 mSv/year
2 mSv/3month
1 mSv/gestation[2]Internal Exposure

General Public(Non Radiation
Worker)Equivalent Dose:
Female Abdomen
Eye Lenses
Skin
Emergency:
Male only, once in his life

2 mSv/gestation[2]50 mSv/year, 100 mSv/5years
300 mSv/year
100 mSv
100 µSv/work[1]	This is not applicable if workers did not report on intention of pregnancy to the Radiation-Safety Supervisor.
[2] During the gestation after declaring pregnancy.

Table 2: Working Level for Exposure Control
Effective Dose

Effective Doseper day
per week

Man
Woman
Man

0.5 mSv
0.3 mSv
1.0 mSv

per year

Woman
Man

0.5 mSv
7 mSv

Woman

2 mSv

―4―

(a)

Figure 3-1: Dosimeters at KEK(a) Personal dosimeter,(b)(b) Alarm meter, (c) DIS dosimeter(c)

Note on the Handling of Dosimeters
Personal dosimeters would be installed in their cases so as to display the name of the carrying personand should be worn on the chest for a man or on the abdomen for a woman, with the name side facing
outward. If these dosimeters are worn at some distance from the body, the dose is underestimated.
An alarm dosimeter sounds an alarm when the integral dose exceeds the preset value, thus urging thebearer to leave promptly the area. Since the battery power is consumed and falls off after an alarm, thisproduces an unstable operation. Therefore, it is thus advisable to use it only after charging the battery.

Be careful with handlingOn the chest

On the abdomen

personal dosimeters

for manfor woman

Figure 3-2: Handling personnel dosimeters―5―Table 3: Criteria for Radiation-Controlled Areas
Area
Name
External Dose Rate andRadioactive Contamination and Concentration
Radiation Controlled Area General Radiation Area Dose Rate
1.5 ~ 20 μSv/hour
1
3
Air Concentration ≤ DAC*
a × 0.1 Bq/cm
Restricted Area
Dose Rate             20 μSv/hour ~ 100 mSv/hour
1
3
Air Concentration >DAC*
a × 0.1 Bq/cm(Contamination Area)
Surface Contamination (α) > 0.4 Bq/cm2

Warning Area
Non-desiginatad Area
Site Boundary(β, γ) > 4 Bq/cm2
Dose Rate> 100 mSv/h
Dose Rate
0.2 ~ 1.5 μSv/hour≤ 0.2 μSv/hour
Dose Rate≤ 50 μSv/year*2
Concentration of Air and Water≤ DACp*3 × 0.05 Bq/cm3

Forbidden Area

Dose Rate

1) Radioisotope concentrations are listed in Table 1 and 2 in the Legal Notification of quantities of radioisotopes.
2) This is determined by the Directors-General.
3) Radioisotope concentrations for the general public are listed in a public notice mentioned in (l) above.

4

Radiation-Controlled Areas(1) Radiation-controlled areas on the KEK campus are shown in Appendix 1. The classification of
the areas are listed in Table 3.
(2) The radiation-controlled areas are normally surrounded by fences; a sign with a radiation
symbol and instructions for entering the areas are posted on the gates of the main entrances.
Many monitors measuring radiation and radioactivity are installed inside the radiationcontrolled areas to control the level of radiation so that it would not exceed the criteria,
designated to each controlled area.

(a)Figure 4-1: Radiation monitor(a) 3He tube of 1 inch diameter with polyethylene
moderator for neutron measurement(b) 10 litter ionization chamber for x/γ -ray

―6―

(b)

5

Entering a Radiation-Controlled Area

In general, only radiation workers are allowed to work inside a radiation-controlled areas. The generalrules for entering radiation-controlled areas are explained as follows:(1) Forbidden Area
Entering this area is strictly forbidden, except for emergency cases, which must be determinedby the Directors-General.
(2) Restricted Area
Access to this area is only allowed to radiation workers who obtain permission in advancefrom the regional radiation-safety officers. When somebody is registered as a radiation
worker, the officer can assign the person’s name to the restricted radiation-controlled area,
if he is scheduled to enter the area daily. The group leader specifies the person’s name in
the application form. According to the registration, KEK-ID cards of radiation workers areregistered with information regarding the restricted areas. While radiation workers with thepermission in advance are allowed to enter the restricted area with their KEK-ID cards, otherradiation workers must submit a Radiation-Work Form (No.2) to the guard at the gate toborrow access cards for entering the area. The restricted radiation-controlled areas, such as thebeam-line tunnels of accelerators are strictly controlled by an access-control system. Please
follow strictly all procedures when you enter such areas.
(3) Contamination Area (PS accelerator, NML beamline, EP1 tunnel, EP2 room, PositronElectron Injector room, Shiryo Sokuteitoh Radiochemistry Laboratory, PF Radiochemistry
Laboratory (BL 27))
This area has been classified as one of the restricted areas, since the surface contamination
by radioisotopes may possibly exceed the criteria. When you enter this area, it is required toobtain advance permission from the regional radiation-safety office using the same procedure
as for the restricted area. Radiation workers who have been assigned to work in the area canenter using their cards; other radiation workers must submit a Radiation-Work Form (No.2)
to the guard at the gate of the area in order to borrow access cards.
Generally, gate monitors (Fig.5-1) or hand-foot-clothes-monitors are installed at the entrance
to check any contamination of clothes, hands, and feet. Please remember that eating, drinking
and smoking are prohibited in this area.
(4) General Radiation Area
Although the entrance procedure depends on the type of radiation-controlled area, KEK-ID andaccess cards are always used for entrance control. Although radiation workers can freely enter
this area because of the low radiation level, only radiation workers who are supposed to workin the area are registered from a general safety point of view. Radiation workers, who are notregistered in this area, can enter by submitting a Radiation-Work Form (No.2) to the guard inorder to borrow an access card.
―7―(5) Warning Area (PS accelerator circumference, PF LINAC circumference SuperKEKB,
PF-AR and DR Dengen-toh)In order to exclude general public and non-radiation workers, this area is surrounded bya fence with locked entrances. A radiation worker may freely enter the area by borrowing
a key. General public or non-radiation workers may enter after reporting to the regionalradiation-safety office.
(6) Personal Key
In order to ensure safety, a personal-key system is employed in special areas, such as thebeam-line tunnels of PS, cERL, LINAC, DR, BT, PF-AR, ATF, STF and SuperKEKB,
where entering during operation is strictly prohibited. This is because of the lethal dose
rate in the accelerator rooms. In the case of entering the area, a KEK-ID or access card
must be placed on the card reader, after which a personal key can be pulled out. Every
individual must carry one personal key to enter the area. This key must be returned to
the key box when leaving the area.

Figure 5-1: Gate monitor

Radioactive air ductRadioactive water pipe

Signs indicating Radiation-Controlled Area
(These signs are specified by law.)
Figure 5-2: Signs for radiation control―8―

Signs established by KEK(not specified by law.)Key Points Concerning Radiation-Safety Control
Radiation-safety control can be classified into the following three major items, listed in the orderof importance: (1) radiation-source control; (2) environment control; (3) personal control.
To ensure radiation safety, it is important that radiation sources, such as radio- isotopes andradiation-generating apparatus, are always maintained in normal conditions: i.e., it is a fundamental
rule of radiation-safety control that these sources must be kept and controlled safely using a safetysystem and shielding.
The second item above indicates the confirmation of radiation-control in each radiation-controlledarea by measuring the radiation or radioactivity around any radiation sources to check that the levelis below the criteria of the controlled area.
The third item is the final confirmation of the personal radiation exposure by the exposure
control using the results of personal monitoring; hence, it is unavoidable to take time to obtain aconfirmation.

KEK-ID and access cards
KEK-ID and access cards are applied to control the access to radiation-controlled areas. The
information, which is registered in the database, determines the areas which can be entered. It isadvisable to follow the instructions below when handling the cards:(1) The cards should not be bent, cut or stained on the surface. A crooked card cannot be readcorrectly by card readers. Cuts or stains on the surface cause reading of incorrect information by card
readers.
(2) It must be noted that the magnetic data in the card are often erased due to exposure to any
magnetic field while working near magnets.

Figure 5-3: KEK-ID and access cards
Personal information is stored in the IC-chip and magnetic
tape on the back side:(a)(a) KEK-ID for staff,(b) access card for contractors,(c) access card for users.

(b)

Please be careful; the card is fragile.

(c)
―9―

6 Radiation-Generating Apparatus and Instructions concerning
Radiation Work
(1) Radiation-Generating Apparatus• Characteristics of the major radiation-generating apparatus are listed on the web page (https://
rcwww.kek.jp/user/top.html).
• Except for the radiation-generating apparatus defined by law, other radiation-generating
installations, such as secondary-beam lines attached to the apparatus, X-ray generators, DC
separators, and klystrons are controlled according to the KEK rules applied to the radiationgenerating apparatus. Hence, it is necessary to report to the radiation-safety supervisor, andto obtain permission from the Directors-General before using these installations. They must
be operated only after the inspection of the safety system and obtaining approval by theradiation-safety supervisor.
(2) Instruction for Radiation Works
Although instructions for radiation workers during their radiation work differ slightly
depending on each radiation-controlled area, the major points are given below. The instructions
for handling radioisotopes are summarized in Chapter 8.
• Several kinds of flashing lamps are employed to indicate the operation of the apparatus.
Yellow flashing lamps installed at the gate of a radiation-controlled area indicate theoperation of radiation-generating apparatus, such as accelerators.
Red flashing lamps indicate the operation of apparatus with high voltage on (magnets,
X-ray generators, DC separators, klystrons, etc.).
Green flashing lamps indicate the operation of apparatus with high pressure gases, such as
cryostat using liquid He (super conducting magnet) and production facilities of high pressure
gas and liquid He.
• When the radiation level exceeds the allowed level of the radiation-controlled area, radiation
monitors sound an alarm. If the alarm rings continuously or frequently, you must promptly
leave the area and inform the regional radiation-safety liaison officers and the RadiationControl Office (TEL:3500).
• Beam lines in the experimental area are usually surrounded by fences and hatches withinterlock doors. When entering such an area, the instructions for entering must be followed.
• If you are working in a restricted area, such as accelerator tunnels, and you hear anannouncement that accelerators will start operation, you must stop the accelerator operation
by pushing emergency buttons.
• If the radiation level exceeds the controlled level during accelerator operation or the handlingof radioisotopes, the area is temporarily fenced off even inside the general radiation area, tocontrol it as a restricted radiation area. Permission to access the area must be obtained fromthe regional radiation-safety officer.

― 10 ―

• The entrance into a restricted area, where surface contamination may occur due to radiation
work, is strictly controlled. Radiation monitors, such as gate monitors and hand-foot-cloth
monitors, are installed at the gate to check the contamination of any human body and goods(equipment, tools, etc.) carried from the outside.
• When activated materials are carried out from radiation-controlled areas, it is necessary toobtain permission from the regional radiation-safety officers. Hence, goods carried outside
must be checked by an article-monitor at the gate whether or not they are activated. If it isdifficult to check the goods by the monitor because of its size, individuals must inform theRadiation-Control Office (TEL:3500) and the items must be checked. Even one tiny bolt
should not be brought out carelessly without permission.

Figure 6-1:

Figure 6-2:

Flashing yellow pilot lamp indicatesthe operation of accelerators.

Emergency button: in the case of an
emergency, accelerator operation
can be terminated.

Figure 6-3:

Figure 6-4:

Three-color pilot lamp;
Red: high voltage, high magnetic field;
Green: high pressure gas (Liquid He) ;Yellow: radiation (accelerator operation).

If the alarm sounds continuously or
frequently, evacuate the area immediately.

― 11 ―

(3) Radiation Work Accompanying Internal Exposure• If entering a beam-line tunnel immediately after operation, the concentration of radioactive
air in the tunnel must be measured in order to ensure that the level is below the standard(DACa×0.1). Please obey the instructions for entering the beam-line tunnel if the waitingtime is specified by the radiation-control center. In the case of an emergency, these rules
are not applicable.
• Any cutting, welding or machining of radioactive materials may result in internal
exposure. Therefore, before undertaking such radiation work, it is compulsory to informthe radiation-control office and to follow the instructions.
(4) Instructions for Radiation Workers• In order to conduct safely radiation work, it is advisable for radiation workers to understandwell the rules and to follow the work procedures and instructions, which are specified ineach facility. At each facility, education and training about the safety systems, such as theinterlock, are given to operators and maintenance workers for radiation-generating apparatus
by the division leader and radiation-generating apparatus supervisor. Especially, if radiation
workers who work on the maintenance of the safety system ignore the rules and procedures,serious radiation exposure may be induced. To ensure radiation safety, it is important forradiation workers to work under the control of a radiation-generating apparatus supervisor
and with their clear instructions about their duties and assignments.

7

Radiation Work for Outside Workers(1) In principle, even outside workers must be registered as radiation workers at KEK, if they
are to work in the radiation-controlled area. The procedure to register outside workers asradiation workers is shown in detail in appendices on the web page (https://rcwww.kek.
jp/user/top.html). Information can be obtained from the Radiation-Controlled Office. The
procedure is different from that of staff members, because, at their companies, they must
be registered as radiation workers, take education and training, health examinationand dosimetry control. After submitting the required forms (No.10), it is compulsory
for outside workers to take the original KEK education course for radiation safety before
starting their radiation work. The procedures for radiation work in any radiation-controlledarea are listed as follows:a. Preparation of the Radiation-Work Form (No.2)
A staff member (radiation-work supervisor), who orders outside workers to carry out
radiation work, must give them thorough instructions concerning their work as follows:
wearing personal dosimeters issued by their organization and safety instructions
concerning radiation and general safety in their work area. Also, the person mustcomplete a Radiation-Work Form (No.2).
― 12 ―

b. After submitting the form to the Radiation Reception Desk, access cards for the gate
control and personal dosimeters are issued.
c. Using the access card, they can enter the area and conduct their radiation work.
d. The access card must be returned every day, even if the radiation work is to continue fora few days.
Outside Worker

Figure 7-1:
Outside worker is visiting the radiation control guard
office and submitting a Radiation-Work Form (No.2)
to borrow an access card.

officer

Personal
Access card

Dosimeter

Work Form(2) At some radiation-controlled areas, it is necessary to obtain a signature on the RadiationWork Form (No .2) for general safety from the responsible person. Areas, where thesignature is required, and the responsible persons are determined in advance. Please refer tothe web page (https://rcwww.kek.jp/user/top.html).
(3) In the case that the entrance procedure is altered by regional radiation-safety officers
because of a low radiation level, the procedures mentioned above are not always necessary.
(4) Radiation works (such as cutting or welding of radioactive materials) which may induceinternal exposure require a permission from an officer in charge in addition to the RadiationWork Form.

Visiting a Radiation-Controlled Area
1. Staff members registered as radiation workers can guide visitors just for showing facilities
in radiation-controlled areas. A form (No.3) for Visiting Radiation-Controlled Area andWarning Area must be filled out and submitted to the guard in charge of the controlled area inorder to borrow access cards and personal dosimeters. Furthermore, a signature of the generalsafety supervisor is required for visiting areas of SuperKEKB, PF-AR DR and BT.
2. In general, a visit can only last for 30 minutes. If it is necessary to visit for more than 30
minutes because of special circumstances, it is compulsory to obtain permission from theregional radiation-safety officer when submitting the form to the guard.
3. In general, it is forbidden to visit any restricted areas in the PS facilities on a Saturday or
Sunday.
― 13 ―

8

Handling of Radioactive Materials

Radioactive materials are listed as follows:a. Legal radioisotopes (RI);
b. Weak radioisotopes (checking sources), which are not controlled by law;c. Nuclear fuel materials (U, Th, and Pu), and nuclear raw materials;
d. Materials contaminated by radioisotopes.
Request for these radioactive materials (to use, purchase, carry from one place to another, bringin, take out, receive, transfer, and produce) must be made to the chief of the Radiation-Control
Office or radiation-safety officers in charge; after completing the required procedures and obtaining
permission, these materials can be handled. Generally, only a radiation worker registered at KEK
can deal with these radioactive materials. It must be noted that the production of radionuclides
using a beam from accelerators can be allowed only after obtaining an approval from the Ministryof Education, Culture, Sports, Science and Technology.

8.1

Handling and Loan of Sealed Radioisotopes(1) All radioisotopes at KEK are to be controlled by the Radiation-Control Office and lentout to users upon request. All details about handling must be obtained from the Radiation
Reception (TEL:3500), since the activities and kinds of sources, places and conditions forusage are limited.
(2) If you need radioisotopes, which are not prepared at the Radiation-Control Office, a purchaserequest must be submitted to the Radiation-Control Office person in charge. The details
should be coordinated with the person.
(3) Inquiries and the loan of radioisotopes are accepted at any time. As of the handling, the items
listed below must be strictly followed:• In the case of the Fuji and Tsukuba experimental halls, you must borrow storages locatedin each safety guard office. Users who use isotopes in the other places must arrange storage
facilities (which must be locked) and ask for conformation from the regional radiation-safety
officers.
• In the case of radioisotopes emitting gamma rays, RI storage facilities with sufficientshielding must be prepared, and the radiation level outside of the storage facilities must be
measured and confirmed to be below the level of the controlled area.
• Loaned sources must be handled carefully and should not be lost or stolen, they should not
be used at other places where their use is not specified.
• A term of loan must be strictly observed. Once the term is ignored, a subsequent loan may
not be possible. In the case of a long-term loan, renewal must be regularly carried out (every
March and September for checking sources).
― 14 ―

• Any user who rents a source must not loan it to other users.
• Every source is placed inside a case with a tag which specifies the name of the source,userʼs name and the term of the loan. Do not remove the tag while in use.
• If you use a source in a special way (installing it inside an apparatus or removing a tagfrom it), a request must be made to the Radiation-Control Office in advance. You need theapproval from the heads of your division, group or center.
• If you find out that a source is missing, broken or contaminated, please immediately
inform the Radiation-Control Office about it (TEL:3500).

Figure 8-1: Various checking sources.

Figure 8-3: Radioactive sources with a tag;

Figure 8-2: RI storage

Figure 8-4: Handling of non-sealed RI.

white and yellow tags are connected

In handling of a non-sealed RI or machining
activated materials, internal exposure
may possibly be induced. Since yourcontaminated body may likely induceinternal exposure, it is necessary to wear
gloves, mask and clothes in order to avoid bodycontamination.

to checking sources and RI,
respectively.

― 15 ―

8.2

Handling of Radioactive Materials, such as Non-sealed Radioisotopes(1) Non-sealed radioisotopes can be used only at RI laboratories inside Shiryo-Sokutei-Toh(Building for the Measurements of Radioactive Samples), and RI laboratories inside PF.
The machining of activated equipment is forbidden, except in the machining room inside
Hoshakabutu-Kako-Toh. A request to use or handle these non-sealed radioactive materials
must be made to a regional radiation-safety officer of the 7-th section in order to obtainhis advice. If you need to handle any non-sealed materials at different places from thelaboratories listed above, permission of the Radiation-Safety Supervisor is required. (Thehandling of non- sealed radioactive materials is not allowed under certain circumstances, andspecial training and education are often required.)(2) When samples containing nuclear-fuel materials are used for an experiment, the places forthe experiment, the quantities and the way of handling are strictly limited. Hence, the request
must be confirmed in advance by the Radiation-Safety Supervisor. Regardless of the quantityof the samples, any use of them is forbidden without permission.

9

Radiation Detectors(1) Radiation workers can borrow radiation detectors from the Radiation-Control Office tomeasure the radiation field at their workplace. If needed, please contact the RadiationControl Office (TEL:3500). Since radiation detectors should be chosen depending on theradiation field any inquiry should be made through the regional radiation-safety officers.
(2) The borrowing of detectors is limited to only a short term. If detectors are necessary to be
used continuously for a long term, the users should purchase their own detectors.
(3) Radiation detectors bought by institutes or divisions should be inspected regularly andcorrected by the Radiation-Control Office more than once a year. When obtaining a new
detector, please register it at the Radiation-Control Office (TEL:3500).

GM Counter(β, Χ, γ)Ionization Chamber(Χ, γ)

Rem-Counter(neutron)

Figure 9-1: Radiation detectors― 16 ―

Scintillation
Survey Meter

10 Suspension, Return, and Termination of Radiation Work,and Radiation Work outside KEK(1) If radiation workers suspend their radiation work temporarily due to an official trip or otherreasons, a form (No.7) of Suspension or Return for Radiation Work should be submitted
to the Radiation-Control Office.
When radiation workers resume their radiation work after suspending, a form (No.7) should
also be submitted. According to these forms, the Radiation-Control Office prepares personal
dosimeters for each radiation worker. Hence, you should not forget to submit these forms insuch cases.
(2) If you do not need to be a radiation worker at KEK due to a change of work, a form (No.8)
for Termination of Radiation Work should be submitted.
(3) In the case of radiation work outside of KEK for experiments or other purposes, permissionof the Directors-General is required. A form (No.6) for Radiation Work Outside of KEK
should be submitted; you can perform radiation work after obtaining permission. Your own
personal dosimeter issued at KEK should be brought with you.
(4) The forms mentioned above are prepared at the business offices of the Institutes, Facilities,
Divisions, and the Radiation-Control Office. You can download the latest version from theweb page (https://rcwww.kek.jp/user/yousiki.htm).

11 Fire Emergency Response Procedures in the RadiationControlled Areas
11.1

Fire Emergency Response Procedures

The fire emergency response procedures in the radiation-controlled areas of KEK are as follows:
1. In the case of a fire emergency, the safety of human life is the most important factor. In the caseof a life-threatening fire, ensure your own safety, notify the information center immediately(TEL:3399) and ask them to summon the fire department.
2. If you discover a fire, alert all persons in the nearby area, and notify both the information
center and the Radiation-Reception (TEL:3500) immediately or ask somebody around you tonotify them. If you discover a minor fire at an early stage, extinguish it very carefully.
3. When you discover a fire or when you are engaged in extinguishing a minor fire during an
early stage, ask a guard who has come to your aid or the information center to summon the fire   department, in a case that the fire might spread dangerously.
― 17 ―

4. The information center, when asked to summon the fire department, must do that immediately,
alert the chief of the account section (head of the self-defense fire division) of the generalaffairs department about the situation, and make an emergency announcement.
5. In the case of a fire emergency, the Shift Leader of the Accelerator Operation in the area
must stop the accelerator immediately and turn off any electric power that is connected to theequipment in the area.
6. As soon as the fire department has been summoned, the operation of all accelerators at KEK
must stop. Do not begin operation of the accelerators until the Radiation-Safety Supervisor has
given an all-clear signal.
7. The response procedures to fire-fighters are as follows:(I) In the case of a fire in a radiation-controlled area, the guard at the gate should provide
dosimeters to the chief of the fire brigade. These dosimeters must be kept in the Guard’s
Office.
(II) When the fire-fighters come to the area, the KEK staff members must instruct them, or act
as follows:a. In those areas designated as a general area, ask the fire-fighters to start extinguishing
the fire as soon as possible because the fire-fighters are not restricted anywhere in
respect to radiation control due to low radiation level.
b. In those areas designated as a Fire extinguishing restricted area, KEK staff members
who are familiar with the area, must accompany the fire-fighters in order to extinguish
the fire promptly. If high radiation levels are expected, or if radioisotopes are in use in
the area, enter the area with a survey meter in order to identify any radiation source.
c. In the radiation control areas, the fire-fighters may enter the area freely having received
permission to enter the control area in advance by the Radiation-Safety Supervisor.
d. The KEK staff should accompany the fire-fighters and provide any necessary
information about extinguishing the fire.
8. A manual of Fire Emergency Response Procedures must be prepared in each radiationcontrol area. Those who engage in fighting minor fires during an early stage must act according
to the manual.

― 18 ―

11.2

Fire extinguishing restricted area

Fire extinguishing restricted area and General area are defined as follows:
1. Fire extinguishing restricted area:(1) In this type of fire zone, it is unlikely that the fire-fighters would receive a dose larger than
0.1 mSv during the work of extinguishing a fire. However, because in this area higher
radiation levels are expected from the accelerator system at some points, or radioisotopes
may be used, KEK staff members who are familiar with the area must accompany thefire-fighters.
(2) In this type of fire zone, although no radiation dose is expected during the work of
extinguishing a fire, other dangers such as high-pressure gas or high voltages may be
encountered. Hence, KEK staff members who are familiar with the area must accompany
the fire-fighters.
(3) In this type of fire zone, no radiation dose is expected during the work of extinguishing afire, but the building has tunnels of a labyrinth structure. Hence, KEK staff members who
are familiar with the area must accompany the fire-fighters.
2. General area: Radiation-controlled areas other than Special or Fire extinguishing restricted area.

― 19 ―

11.3

Facilities and Rooms Assigned as Special and Fire extinguishing restricted area

The radiation-controlled areas classified as Fire extinguishing restricted area are listed in Table 4.

Table 4: The radiation-controlled areas classified as Fire extinguishing restricted area
Facilities

Fire extinguishing restricted area

Proton Synchrotron

Main Ring

Facility
Neutron and Meson

NML beam line

Science Laboratory
Counter Hall (CH)EP2 room(PS Experimental Hall)PF Facility

EP1 beam line
BL-27

Radiation Chemistry Lab.

Non-sealed source laboratory

RI Experimental Lab.

Storage room of RI

Irradiation Facility

Storage Container of RI

Target storage building

Storage roomhttps://stw.kek.jp/stpg/hso/files/2014/11/kasaitaiou.pdf― 20 ―

11.4
1.

Signs Indicating Fire extinguishing restricted area
Signs indicating Fire extinguishing restricted area.
Zones inside the Radiation-Controlled Areas
Fire-fighters may not receive a dose larger
than 0.1 mSv but higher radiation levelmay be found at some points, or RI may
be in use, so the KEK staff members must
accompany the fire-fighters.
（横型）

2.

Signs indicating Fire extinguishing restricted area other than radiation:
（横型）

（縦型）

（横型）
（横型）

（縦型）
（縦型）

（横型）

（縦型）

（横型）

（縦型）

（横型）

（縦型）

（横型）

（縦型）

Reference
1.

（縦型）

This article is translated from “Radiation Safety Textbook” in Japanese(Houshasen No Anzen No Tebiki), published by Radiation Science Center, KEK, 2021.

― 21 ―

Appendix 1. Radiation Controlled
Areas in KEK (2022)― 22 ―

Appendix 2. Divisions of Radiation
Controlled Areas in KEK (2022)― 23 ―

― 24 ―

Study Guide for Radiation Safety
1st edition, April, 2001
2nd edition, October, 2022
Edited and published by
Radiation Science Center
High Energy Accelerator Research Organization
Oho, Tsukuba, Ibaraki, 305-0801, Japan