close

Se connecter

Se connecter avec OpenID

cern laboratory presentation

IntégréTéléchargement
CERN / DOSIMETRY FOR RPE
Pierre Carbonez : DGS-RP-DC
04/02/2015 P. Carbonez
CERN LABORATORY PRESENTATION
CERN LHC
CERN LABORATORY PRESENTATION
LHC: circumference 27 km , SPS: 7 km,
CERN’s Meyrin site: 1km long
CERN LABORATORY PRESENTATION
Located on the French – Swiss border near Geneva, CERN is the world’s largest particle physics laboratory
SOME FIGURES
10 000 Persons on the different sites every day
45 km of accelerator tunnels ( 30 mi)
~ 60 access points
9000 personal dosimeters distributed / calibrated every year
~ 50 000 accesses every shutdown
~ 1000 radiologically classified areas
CERN DIS1 dosimeter
LEGAL CONTEXT
OFSP (CH)
Code du Travail (FR)
Références juridiques :

Articles R. 4451-8, R. 4453-19, R. 4453-24 et R. 4456-17 du code du travail,

Arrêté du 30 décembre 2004 relatif aux informations individuelles de dosimétrie
des travailleurs exposés aux rayonnements ionisants.
1
MISE EN ŒUVRE DE LA DOSIMETRIE PASSIVE
Chaque employeur est tenu d’organiser le suivi dosimétrique de référence des travailleurs
placés sous son autorité et qu’il a préalablement classés. A ce titre, lorsque l’exposition est
externe, il met à disposition de ses salariés un dosimètre passif adapté au type de
rayonnements et au niveau de dose et s’assure de son port.
Suivant les mêmes critères, lors d’opérations en zone contrôlée, l’employeur fournit à ses
salariés un dosimètre opérationnel dont il assure l’entretien et le contrôle.
Article L1333-8
Modifié par Loi n°2001-398 du 9 mai 2001 - art. 3 JORF 10 mai 2001
La personne responsable d'une activité mentionnée à l'article L. 1333-1 met en
oeuvre les mesures de protection et d'information des personnes susceptibles
d'être exposées aux rayonnements ionisants rendues nécessaires par la nature et
l'importance du risque encouru. Ces mesures comprennent l'estimation des
quantités de rayonnement émis ou des doses reçues, leur contrôle ainsi que leur
évaluation périodique.
Arrêté du 23 mars 1999 précisant les règles de la dosimétrie externe des
travailleurs affectés à des travaux sous rayonnements en application des
articles 20 bis et 25-I du décret du 28 avril 1975 modifié et des articles 31
bis et 34-I du décret du 2 octobre 1986 modifié
I - Champ d'application
Les travailleurs directement affectés à des travaux sous rayonnements ainsi
que les salariés amenés à intervenir en zone contrôlée sont soumis à un risque
d'exposition externe et/ou interne.
En conséquence, l'employeur est tenu de prévoir pour chacun de ses salariés
la mesure de l'exposition externe par le recours à une dosimétrie individuelle
en temps différé (dosimétrie passive telle que, par exemple, la dosimétrie
photographique).
HISTORY
Before 2001 : The famous “FILM BADGE”
2001 KODAK STOPPED TO PRODUCE THE “NEUTRON FILM”
The neutron film was replaced by a CR-39 track-etch dosimeter from Landauer
2004 : THE NEW DIS-1 from RADOS
RF ID
CR 39 - Track etch from PSI
DIS Dosimeter Hp(10)/Hp(0,07)
CERN DIS Dosimeter : 6500 units
CERN AREA CLASSIFICATION
DMC mandatory
CONTROLLED AREAS
< 10 uSv/h
<3
< 3uSv/h
SUPERVISED AREAS
NON DESIGNATED AREA : < 1 mSv per year
< 0,5 uSv/h
EDMS 810149
DIS/ DBR Technology
How does it work ?
Combination of Ion chamber and charge storage element.
Air or Gas
Non volatile analog memory cell surrounded by a gas
filled ionization chamber,
For photon radiation initial interaction take place in the wall material
and secondary electrons generated are collected on the floating gate of a Mosfet
transistor
Memory cell surrounded with a conductive wall forming a Ion chamber between the wall
and the floating gate.
DIS/ DBR Technology
DIS Unit : Direct Ion Storage
- Measurement in Hp(10) and Hp(0.07)
- Ranges from 1uSv to 40 Sv.
- Non destructive reading with dedicated readers.
- Passive dosimeter with instant reading function.
- Not sensible to MF or RF
- Integrated memory for user identification.
- 10-year battery lifetime.
DIS/ DBR technology
DBR-1 : Direct Badge Reader
- Direct reading of Hp(10) and Hp(0.07).
- Can be used locally or on the network.
- Internal battery in case of power failure.
- Internal memory for configuration parameters.
- Keypad for job codes or security accesses.
Quantities and types
Since 2004
+
55 DBR
6500 DIS
Since 2013
+
1500 DMC
Doses calculations at CERN
50 LDM
19
DBR locations on the CERN sites
Network infrastructure
HR - Fundation
Dosimetry
ELDDB
Consolidated
ACCES -ADaMS
CERN network
CERN Interface
Where is “DIS” coming from ?
=
Doses calculations at CERN
24
BACKGROUND SUBTRACTION
Dose displayed = sum of doses since the attribution of dosimeter
Sum of doses = sum of net past monthly doses + current reading background subtracted
Background subtraction = period dose - number of days since last period x 2,33 uSv
E.g. Line 10 : 28,91 = 125 - ( 48,04 x 2,33)
Doses calculations at CERN
25
DOSE ROUNDING
Swiss law applied at CERN
[ 0 – 75 uSv ]
= 0 mSv
[ 76 – 149 uSv ] = 0,1 mSv
[ 150 – 249 uSV ] = 0,2 mSv
[ 250 – 349 uSv] = 0,3 mSv
.
.
.
Doses calculations at CERN
26
Dose Process : ideally
-
DIS Reading by the user.
-
Dose stored in the table “new events of virtual server”.
-
Doses verification by dosimetry service, dose passed in “lock events” of
virtual server.
-
Dosimetry service calls the doses from virtual server to dosimetry database,
the doses calculation recommendation 2004 is applied.
-
Dose is stored in the dosimetry database and readable online by the user,
Doses calculations at CERN
27
Dose calculation : reality
The background on the whole CERN territory is not the same everywhere: variyng
from 50 uSv to 80 uSv / month depending on your office location. But the background
subtraction is the same for all dosimeters. This leads to overcorrection of the
background ( Allo…my dose is always 0 ?) or undercorrection of the background
( Allo…the dosimeter stays always in my drawer but I am accumulating doses).
The 75 uSv rule is applied per period that should be a month but the period is defined
by the user not by the system.
The reading frequency will impact on the final dose ( see next slide)
Some dosimeters are at the end of their lifetime ( battery inside)
At very low doses there might be deviation of +/- 20% on
the dosimeter accuracy.
Doses calculations at CERN
28
Period trick : case 1
uSv
day
Reading 1
…
Reading 2
1
2
3
4
5
6
7
8
9
10
Brutto value
3,168
6,336
9,504
12,672
15,84
19,008
22,176
25,344
28,512
31,68
46
47
48
49
50
FINAL DOSE
2uSv / Day
Days of use
1
2
3
4
5
6
7
8
9
10
145,728
148,896
152,064
155,232
158,4
158,4
46
47
48
49
50
50
bckgrd comp.
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
100
Rounded reading
3
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
158
'monthly' dose
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
58
VALUE FOR THE DATABASE ( sum brutto doses - (days *2uSv)
Reader display : 0,06 mSv
dose in ELDDB
1
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
58
58 uSv
Official CERN dose = 0 mSv
Doses calculations at CERN
29
Period trick : case 2
Reading 1
Reading 2
Reading 3
Reading 4
Reading 5
Reading 6
Reading 7
Reading 8
Brutto value
3,168
6,336
9,504
12,672
15,84
19,008
22,176
25,344
Days of use
1
2
3
4
5
6
7
8
2uSv Day
bckgrd
compensation
2
2
2
2
2
2
2
2
uSv
Rounded
reading
3
6
10
13
16
19
22
25
uSv
'monthly' dose dose in ELDDB
N/A
1
N/A
2
N/A
4
N/A
5
N/A
6
N/A
7
N/A
8
N/A
9
…
Reading 28
Reading 29
Reading 30
Reading 31
FINAL DOSE
88,704
91,872
95,04
98,208
98,208
28
29
30
31
31
2
2
2
2
62
89
92
95
98
98
N/A
N/A
N/A
0
0
33
34
35
36
36
VALUE FOR THE DATABASE ( sum brutto doses - (days *2uSv) = 36 uSv
Reader display : 0,04 mSv
Official CERN dose = 0 mSv
Doses calculations at CERN
30
Infinite possibilities:
Dose person 1 = 58 uSv
Dose person 2 = 36 uSV
Let’s now assume they both took 20 real uSv for the same “month”
Dose person 1 = 78 uSv => CERN dose : 0,1 mSv
Dose person 2 = 56 uSV => CERN dose : 0 mSv
Now change the background, the period, dosimeter sensitivity, real dose….
Doses calculations at CERN
31
Operational dosimetry
-
Months are calendar months defined by the system
-
No background subtraction ( periods of < 8 h )
-
No operation on the doses
- Monthly doses are simply the sum of daily doses
2/29/2016
Document reference
32
DOSIServ Client
Doses calculations at CERN
33
IMPACT
Real time dose transmission to IMPACT where doses are viewable by authorized persons
Doses calculations at CERN
34
DO NOT COMPARE !
Personal dosimetry
Official, legal, mandatory
Operational dosimetry
Optimisation, safety, alarm
=
No background subtraction
Background subtraction
Versatile periods
75 uSv rule
DOSES WILL NEVER
BE EQUAL
Calendar periods
No dose correction
+ Sensitivity and response are different
+ Not worn at the same place on the body
Doses calculations at CERN
35
Assignment of dosimeters 2000-2015
Monitored Personnel
12000
10000
Persons
8000
6000
4000
2000
0
2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015
Monitored Personnel 7195 7080 5977 5646 5788 4666 5990 6082 5853 6315 6969 7347 8061 8546 9580 9814
Regular
4958 3661 3764 3372 3908 3844 4368 4400 4150 4717 5218 5463 6076 6054 6486 6503
Dosimeters assigned during LS1 : 15573 units ! ( Mar 2013 – Nov 2014 )
LS1 MONTHLY DIS ASSIGNEMENTS
1000
900
DIS ASSIGNEMENTS
800
700
600
500
400
300
200
100
0
Collective Personal Dose equivalent 1994-2015
Collective dose equivalent (person-mSv)
Collective Personal Dose Equivalent
1400
1200
Gamma/Beta
Neutron
1000
800
600
400
200
0
94
95
96
97
98
99
0
01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
213,8 man mSv in 2015
38
Individual Doses per dose range: 2006 - 2016
Dose
Persons
Persons
Persons
interval Concerned Concerned Concerned
(mSv)
years
2006
2007
2008
4192
5131
5143
0.0
898
1020
0.1-0.9 1738
33
40
1.0-1.9 37
2
3
2.0-2.9 17
1
1
3.0-3.9 4
1
1
4.0-4.9 2
5.0-5.9 0
0
0
> 6.0
0
0
0
SUM PERS
5990
6066
6208
Persons
Persons
Persons
Persons
Persons
Persons
Persons
Concerned Concerned Concerned Concerned Concerned Concerned Concerned
2009
5042
1219
39
13
2
0
0
0
6315
2010
5418
1514
31
6
0
0
0
0
6969
2011
5315
1984
31
7
0
0
0
0
7337
2012
6002
2030
29
0
0
0
0
0
8061
2013
6273
2188
82
3
0
0
0
0
8546
2014
7616
1816
133
14
1
0
0
0
9580
9800 dosimeters assigned in 2015 – NEW RECORD!
2015
8704
1108
2
0
0
0
0
0
9814
Other Dosimeters at CERN
Finger rings – extremity dosimeters
Neutron dosimeters CR-39
TLD : provided by PSI
Recommended by RPO
Current limit 500 mSv/year
Exchanged 1 time /month
Track Etch detector provided by PSI
Present on every dosimeter
Detection Limit 500 uSv
Exchanged 1 time / year
Advertisment :
NEW
Operational dosimetry
WHY CERN NEEDED TO CHANGE ITS OPERATIONAL SYSTEM ?
KEEP UP TO DATE WITH CUTTING EDGE TECHNOLOGY
WHY DID CERN NEED TO CHANGE
ITS OPERATIONAL SYSTEM ?
Regular Tripartite Meetings
DECISION TO CHOOSE LDM + DMC
SYSTEM UPGRADE BEFORE LS1
+
1000
+ 500 DMC 3000
MGPi LDM 2000
X 50
Use of the IMPACT code at CERN
Possible configurations
Assigned dosimeters
Pool of dosimeters
•
•
•
The dosimeter is assigned to a
worker, when the dose is read it is
automatically logged into the RP
database (Db) under his/her name
The user only have to type the
IMPACT number on the reader.
Before accessing
Ready to access
•
The dosimeter is not assigned to a
worker, when he/she access he
needs to type first his/her CernID
and then he/she has to type the
IMPACT number on the reader.
At the reading, the dose is
automatically registered under
his/her name in the Db
Type your CernID
At exit: after reading
Type the IMPACT number
Operational dosimetry : user interface
HR - Fundation
Dosiserv
CERN network
Dosimetry
ADVANTAGES
-
Visits electronically logged ( avoiding manual entries, delays, errors )
- Real time follow-up of activities.
- Real time reporting for companies.
- Enhanced statistical reports.
- Fast problem tracking.
- Multiple configuration possibilities.
- No major failure hardware / software.
PERSPECTIVES
-
Integrate the DMC presence check in our access systems
-
Integrate a user friendly IMPACT interface near LDM readers
-
Extend the possibility of a dosimeter pool with DMC distributors
-
Integrate a WRM set.
… and
DMC mandatory
CONTROLLED AREAS
= 40 additional readers !
The project is not finished.
SUPERVISED AREAS
NON DESIGNATED AREA : < 1 mSv per year
Don’t forget to read your dosimeter
CERN Dosimetry Service
THANK YOU
Auteur
Document
Catégorie
Uncategorized
Affichages
13
Taille du fichier
7 676 KB
Étiquettes
1/--Pages
signaler