Radioactive Sources service web site
The Radiation Protection Group
DGS/RP maintains a stock of radioactive sources for various uses. The RP Group is in charge of the purchase and loan of the radioactive sources, holders and shielding, as well as the registration and updating of the radioactive sources database. The
RP group performs periodic inspections on sources installed in various parts of CERN.
The service is open every day from 8:00am to 5:00pm
- TÚl: +41 22 76 73171
- Fax: +41 22 76 69200
Use of radioactive sources
|a. Length of loan and periodic checking
Any request for sources should be made using the
Protection Group DGS/RP, which holds a
stock of the most commonly used radionuclides (22Na, 54Mn, 55Fe,
57Co, 60Co, 65Zn, 90Sr
+ 90Y, 106Ru, 109Cd, 134Cs, 137Cs,
152Eu, 207Bi, 241Am), will contact you
later. Every person who uses a radioactive source must be in possession of an
dosimeter and cannot be registered as short-term visitor (VCT).
At the time of the loan, an expiry date for an inspection will be given. It is then the responsibility of the source-user to arrange with the Radioactive Source Service an inspection of the state of the source for the loan-renewal
or the return of the source when it is no longer required.
- For special sources (radionuclides not kept in stock, non-standard
holder, etc...), the RP Group provides advice to users in order to find
the most appropriate solutions.
- Radioactive sources used and imported at CERN must be sealed according to
- An authorization from RP Group is required before the source is moved:
internally at CERN (transfer from one room or site to another) or
externally (import or export).
- Personal dosimeters must be
worn at all times when a radioactive source is being used. You
will be provided with other dosimeters (operational or extremity dosimeters)
|d. Using and storing the source safely
- Each user is responsible for borrowed sources and is provided
safety instructions on their use. This information
must be passed on to all those using the sources. If in doubt, do not hesitate to
contact RP Group (73171) for additional information.
- Sources must be returned to the RP Group if they are no longer in
use or if the person responsible for it is leaving CERN. However, if they remain in
the same users group, the name of the new person in charge will have to
be forwarded to the RP Group.
- For dangerous and highly dangerous sources, the RP Group supplies storage safes
which are resistant to fire. Care must therefore be taken to ensure that the sources are stored inside them
and locked when not in use. Lower-radioactivity sources must be locked
away in small clearly marked metal boxes.
- Every source must be accompanied by a small yellow warning sign.
- The presence of dangerous or highly dangerous sources and their location must be clearly indicated
at the entrance to premises where they are used. During lengthy uses not requiring the physical presence of an operator, NO ENTRY or
NO CLEANING signs must be posted in the area concerned.
- Users must keep an up-to-date map (useful to the CERN Fire Brigade
in case of problem) showing the location of all sources which are under
- For obvious reason, abrasion or etching of the surface of the
sources and any structural modifications to the latter are prohibited.
- Do not use a source in a "hazardous" environment (corrosive, vacuum, high or low temperatures, ...), without agreement of the RP group.
- Never place a source in the vicinity of, or in a beam.
- For gamma radioactive sources of high intensity, please consult
the specific requirements available in
External irradiation and contamination risk
The three parameters to be taken into account to
minimize radiation doses are:
a. Exposure to gamma radiation
the distance from the source,
thickness of the shielding,
the length of exposure.
The RP Group assists with the installation of high gamma
activity sources and draws up special instructions.
b. Exposure to beta radiation or X rays
In the case of
which are widely used at CERN, localized exposure of skin and eyes remains
the major hazard. For a 37 MBq (1 mCi) source, the beta radiation dose rate
is of the order of 10 Sv/h.
To avoid any accidental exposure, make sure prior to
handling the source that the collimator is in the off position. Once the
collimator is on, never point the unscreened part of the source towards the
eyes, the hand or any other part of the body.
Although having equivalent activities, doses are lower in case of X-ray or
low energy g emitting
109Cd, etc....), the same rules as for
beta sources must be applied.
c. Contamination risk
There is a latent risk of contamination from open alpha sources
and from sources where the alpha emitter (essentially
deposited by electrolysis onto a metal disk. It is therefore strictly forbidden
to touch the radioactive deposit of such sources with the fingers. The dose
when ingested or inhaled is very high (0.2 ÁSv/Bq by ingestion - 27 ÁSv/Bq by inhalation). If this figure is compared to the CERN
annual dose limit (20 mSv), it will be realized that this value can very rapidly
be exceeded by ingesting or inhaling alpha emitters.