cadarache, building 519, 14 february 2007 henri maubert

Radiological Protection, Cadarache, 14 February 20071

Cadarache, building 519, 14 February 2007Cadarache, building 519, 14 February 2007

Henri MaubertHenri Maubert

Radiological Protection Training

footer text, location, date2

Radiological Protection Principles 1Radiological Protection Principles 1

Prompt effects of radiation exposure

the severity of the effect depends on the dose

1

Probability of occurrence of an

effect

exposure

Dose limit

Threshold

zone

0

Ex: erythema

Effect of radiation exposure : threshold model



•Delayed effects of radiation exposure

• Example : cancer and leukemia

•Severity not dependent on the dose

•Probability of occurrence increasing with the dose

•Uncertainty about the existence of a threshold

Assumption that there is no threshold

For more information : http://www.ccnr.org/ceac_B.html



• No threshold linear hypothesis

Probability of occurrence of an

effect

Dose (Sv)

One time dose

Chronic dose

Homothetical factor

0,50,2



• Probability of occurrence of a cancer :

P = 5.10-5 mSv-1

100 000 people with 1 mSv each will lead to 5 more cancers

Normal occurrence 25 % 2500 cancers

• No threshold means that the risk is never equal to zero

• Look for an exposure

As Low As Reasonnably Achievable



1. Justification– The benefits for the society justify the

potentially harmful effect of exposure

2. Optimisation– Demonstrate that the exposure is as low as

possible, taking into account sociological and economic factors

3. Limitation– Regulatory safety net


Legal framework of radiological protectionLegal framework of radiological protection

• European directives– 96/29 protection of workers and general public

against the danger of ionising radiations– 97/43 protection in relation to medical exposure

• French decrees– 2002-460 about public protection– 2003-296 about workers protection– 2003-295 about protection in emergency

situation– 2003-270 for medical exposure


Architecture of documentsArchitecture of documents

European Directives 96/29 and 97/43

Decree 2003-270medical

Decree 2002-460

public

Decree 2002-295

emergency

Decree 2002-296workers

public health code work code

Ministerial order 26 October 05

Tests and measurements

Ministerial order 15 may 06

Radiological zoning

For wastes, pollution and fire :

Ministerial order 31/12/1999


Decree 2002-460Decree 2002-460

• Limitation of dose– 1 mSv/year individual dose in the population

• Authorization regime for all the sources of ionising radiations,

– Radioactive materials in processes,– Nuclear fuel,– Radioactive sources, including in devices– Particles accelerators


Decree 2003-296 (1)Decree 2003-296 (1)

• The head of the establishment (HE) is responsible for Radiological Protection

– Ensures the coordination of safety measures– Nominates a Person Competent at

Radiological protection (PCR)– Follows the ALARA process

• ALARA in design• ALARA for each work task and individual

– Sets up a dose monitoring program


Decree 2003-296 (2)Decree 2003-296 (2)

• Dose limitation for 1 year– 20 mSv effective dose– 500 mSv pour les extrémities (hands, feet) and skin >1 cm²– 150 mSv for the lens of the eye– For pregnant women, < 1mSv for the child to be born– 16 to 18 y < 6 mSv, 150 mSv extremities, 50 mSv lens– These limits may be exceeded by a factor of 2 with special

authorization

• Measurement of doses– Passive (film, TLD, RPL), reference validated by the work

doctor– Active, real time electronic device with alarm


Decree 2003-296 (3)Decree 2003-296 (3)

• Arrangements in work space

• Around the source, after taking the advice of the PCR, the HE sets up

– a supervised zone• if dose on 12 months : [1 à 6[ mSv(1)

– a controlled zone • if dose on 12 months > 6 mSv(1)

(1) 6 mSv, or 3/10 of other limits for extremities, crystalline…

(1) In normal conditions of

work

Zoning is based on the potential dose to workers


Decree 2003-296 (4)Decree 2003-296 (4)

• Inside the zones : – The sources should be signaled,– Prohibited to eat, drink, smoke, no relaxation room in controlled zone– The HE sets up a program of radiological

surveillance (Ministerial order 26 oct 05)

• The HE defines protective measures– Collective and individual– Takes advice from the PCR, and CHSCT(1)

– The work doctor gives an advice for special equipment like complete suits, respirators…

(1) Committee for Hygiene and Safety,

(Direction + labor unions)

Matière radioactive


Decree 2003-296 (5)Decree 2003-296 (5)

• Classification of workers (by HE with work doctor advice)

– If exposed to more than 6 mSv/12months in normal condition of work :

• Category A– If exposed, and not category A,

• Category B

• Training – workers must benefit from a training at least every 3 y– must be informed about the risks (especially women)– must be given a note about risks, a job description

including all risks must exist


Decree 2003-296 (6)Decree 2003-296 (6)

• Nominative dosimetry record– Confidential (worker, work doctor, personal doctors,

PCR, in case of death or disability eligible party (spouse)), HE only for active dosimetry)

• Statistical dosimetry records– Same + HE

• Organization of radiological protection– The HE nominates a PCR, and coordinates the

safety, if there are contractors– For each contractor, the employer is responsible for

the safety of his employees


Decree 2003-295 ; emergency situation (1)Decree 2003-295 ; emergency situation (1)

• Intervention personnel– Group 1

• Dose < 100 mSv, 300 mSv to save people• List established before hand, volunteer at the time

of intervention with proper information

– Group 2• Dose < 10 mSv


Order of 15 may 2006 ; radiological zoning (1)Order of 15 may 2006 ; radiological zoning (1)

• Purpose of the order– Set up the zones according to actual risks

• Source characteristics, results of radiological surveillance program

– Define reference values to classify the rooms• Risk without individual protective equipment• External and internal exposure• Values readily measurable

– Define rules of behaviour for safety



• Easy to understand for workers

Radiation source Increasing risk

Facility

Zone D

Zone C

Zone B Zone A

Zone F

Zone G

Zone H

Zone E

Zone I



E potential effective dose in 1 hr, DR dose rate, H equivalent dose in 1 hr

Zone without

regulation

- Dose

D< 80 µSv / month

- Radiological surveillance for zones adjoining regulated areas, if there is a contamination risk

Supervised zone

E< 7,5 µSv

Controlled zone

green

E< 25 µSv

yellow

E< 2 mSv

&

DR < 2 mSv/h

orange

E< 100 mSv

&

DR < 100 mSv/h

Restricted zone

E> 100 mSv

Controlled zone

Controlled zone

red

Specially regulated zones

regulated zones

Whole body

Extremities

HT< 0,2 mSv HT< 0,65 mSv HT< 50 mSv HT< 2500 mSv HT> 2500 mSv



• Examples of layout

supervised

Access

controlledAdd rules of entrance



• Air Contamination– No reference values in the decree– Equivalence between internal and external doses– Zoning should be determined without the use of

individual protection devices– Proposed operational derived value

• ODV such that dose rate = 25 µSv/h– Limit between green and yellow zone– Equals 2.5 DAC

• Surface contamination : do a specific study !


Air Concentrations ; Operational Derived ValueAir Concentrations ; Operational Derived Value

• Air concentration for HTO

• Calculation1 ODV = 25E-6 [Sv/h] / (1.2 [m3.h] * 2.7E-11 [Sv/Bq] )

Dose coefficient takes into account the skin transfer2.7E-11 = 1.8E-11*1.5 (inhalation dose coeff 1.8E-11 Sv/Bq from directive

96/29)

supervised controlled

Resctricted

HTO, Bq.m-3 < 2.3E5 < 7,7E5 < 6.2E7 < 3.9E9 > 3.9E9

controlled controlled controlled

HTO ODV < 0.3 < 1 < 80 < 4000 > 4000



• Inside the regulated areas– the sources should be clearly signaled– only a part of a room may be regulated– signaling should be such that it is impossible to enter

by mistake– in red zones, the limits are the walls– red zones should be locked– If the source is not continuous ( X-rays generator for

example), zoning may evolve according to the use of the device, with safety arrangement

Device workingControlled

Device not workingSupervised



• Access conditions

Zone without

regulation

Supervised zone

Controlled zone

green yellow orange

Restricted zone

Controlled zone

Controlled zone

red

Active and passive dosimeters

No temporary contracts

PCR authorization

HE aut.

Passive dosimeter


Entrance in regulated areasEntrance in regulated areas

• If there a possibility of contamination

– Avoid all personal belongings (other than necessary, glasses, notebook, for example)

– Install a contamination survey at the exit of zones with a risk of contamination

• For ITER that means a change room in the personnel access building, and according to the room or type of work, contamination surveys, airlocks, permanent or temporary



• General arrangements– Zoning should be defined in an internal document that may be

inspected– Reference values should easy to check– A test plan should be established and run

• There are sections about mobile apparatus and transport

• Zoning is not the only tool for radiological protection

– ALARA studies– Work task description– Dose rates at the work station lower than limits


ALARA in design (1)ALARA in design (1)

DetrimentProtections

TOTAL

Optimum

COST



selection of the optimal solution

Work task description (manpower, duration, frequency, personnal protective equipment)

Work area description (doserate, radiation

sources, contamination, shielding…)

Prediction of doses (individual, collective, internal, external)

Study of different variants, modification of processes and protections, identification of solutions leading to dose

reduction



• Dose target at the start of the design is not mandatory

– It useful to get one that will act a constraint, on a basis of social acceptance for example

• ITER– Collective dose < 0.5 Sv/y– Individual dose < 10 mSv/y

• Proportionate the volume of the ALARA study to the issue

– Use of a threshold, for example 5% of total dose


ALARA in operation (1)ALARA in operation (1)

• Two levels1. Optimize the doses for a specific task, ex :

– maintenance of a component– repetitive work in controlled area…

2. Optimize for each worker• A worker may have

different tasks

Think about equityAvoid transfers of risk

ALARA

PROCESS

ALARA

PROCESS

DOSE TARGETDOSE TARGET

FEEDBACK

ANALYSIS

FEEDBACK

ANALYSIS

ANALYSIS OF

PERFORMANCE

ANALYSIS OF

PERFORMANCE


Waste zoning : Ministerial order of 31 Dec 1999Waste zoning : Ministerial order of 31 Dec 1999

• Mandatory to make a study about wastes in order to reduce their volume and toxicity

– Chemical, radiological, biological…– Sort the wastes according to their

characteristics and disposal channels

• Define zones for – radiological wastes– conventional wastes

Radiological cleanliness

Find NONO Bq where thereshould not be any


Definition of contaminating zoneDefinition of contaminating zone

• Presence in the room of– loose contamination– possible activation– potential confinement loss in normal operation– past contamination incident

• Indicative clearance threshold– Detection limits of measurement equipment and

level less than 1/10 of exemption levels in Directive 96/29 (1/100 for tritium)


Waste zoningWaste zoning

• All wastes from a CZ go to radwastes

• When going out of a CZ there is contamination check, (and an airlock on the path to exit)

• Equipment must be checked for contamination with a clearance threshold

•

Non Contaminanting Zone

NCZCoventional wastes

Contaminanting Zone

CZRadiaoctive wastes

cadarache, building 519, 14 february 2007 henri maubert

Documents

msv extremities

cm150 msv

msv lensthese limits

radiological protectionensures

dose limitation

cancersnormal occurrence

doseprobability of occurrence

dose1probability of