A. DORSIVALSAFERIB 20021 RADIATION PROTECTION IN A CLASS "A" TYPE LABORATORY SAFERIB 2002

A. DORSIVAL SAFERIB 2002 1

RADIATION PROTECTIONRADIATION PROTECTION

IN A CLASS "A" TYPE LABORATORYIN A CLASS "A" TYPE LABORATORY

SAFERIB 2002SAFERIB 2002


RegulationsRegulations– A few definitions, guidelines and limits extracted

from the Swiss ordinance ORaP

Workplace equipmentWorkplace equipment– What are the basic equipments in a class A type

laboratory

Exposure risksExposure risks– How to measure and reduce external and internal

radiation exposure

OverviewOverview


VocabularyVocabulary Unsealed sourceUnsealed source

– Source that does not meet the definition of a sealed source and can cause a contamination

– A sealed source is any radioactive material encased in a capsule designed to prevent leakage or escape of the material

Radioactive contaminationRadioactive contamination– Undesired radioactive material that is deposited on

the surface of or inside structures, areas, objects or people

– Can be “loose” (indirectly measurable with a smear)– Can be “fixed” (directly measurable on surface with a

probe)


The Swiss OrdinanceThe Swiss Ordinance

TheThe licensing limit “LA”licensing limit “LA”– Activity (Bq) derived from the committed effective dose by

inhalation» The intake by inhalation of 1 LA gives a committed

effective dose of 5 mSv RS 814.501 Annex 3, columns 10

TheThe incorporation dose factors “incorporation dose factors “eeinhinh” and “” and “eeinging””– For the considered isotope, the inhalation or respectively

ingestion of 1 Bq causes the given effective dose» Source: Directive Euratom 96/29

RS 814.501 Annex 3, columns 4 and 5


The Swiss Ordinance: guideline valuesThe Swiss Ordinance: guideline values

The concentration of activity “CA”The concentration of activity “CA”– The air inhalation with 1 CA concentration of activity

during 40 hours per week and 50 weeks per year (persons occupationally exposed to radiation) causes an effective dose of 20 mSv

» CA [Bq/m3] = 0,02 / (einh · 2400) RS 814.501 Annex 3, columns 11

The surface contamination “CS”The surface contamination “CS”– Expressed in Bq/cm2, this guideline value is the most

conservative result of 3 calculation modes and applies for material leaving controlled areas:

» Skin irradiation, Ingestion, Inhalation RS 814.501 Annex 3, columns 12


The Swiss Ordinance : workplacesThe Swiss Ordinance : workplaces

Workplace classificationWorkplace classification

Activity used per operation and per day(RS 814.501 Article 69)

Laboratory typeLaboratory type ActivityActivity

Class CClass C 1 < LA < 1001 < LA < 100

Class BClass B 1 < LA < 100001 < LA < 10000

Class AClass A 1 < LA < upper permitted limit1 < LA < upper permitted limit


Class A laboratories :Class A laboratories :basic requirementsbasic requirements

General characteristicsGeneral characteristics– Located away from circulation– Isolated from other workplaces– Grouped to form a unit (controlled area)– Hierarchically organized following risks

VentilationVentilation– Minimum air renewal : 5 h-1

– Hierarchic depression– “Absolute” filtration– Release chimney– Control system (radioactivity, flows, pressures…)– Backup power supply



Radioactive storage areaRadioactive storage area– Low background for

contamination measurements

– External exposure reduction

Radioactive release Radioactive release managementmanagement– Gas and aerosol

monitoring– Liquids monitoring

(backup reservoir)Isolde release measurement


Collective equipmentCollective equipment– Fume cupboards (dynamic confinement)– Glove box (static confinement)– Appropriate radiation protection monitors– Radioactive waste containers– Decontamination facilities– “Hot and cold” changing rooms

Individual equipmentIndividual equipment– Working clothes (overall, gloves, special shoes or

overshoes…)– Breathing protection device




CEA-Marcoule-AtalantePhotos: Th. FOULON


External exposure risksExternal exposure risks

External exposureExternal exposure– Time, distance, shielding

» Hot cells with lead-glass and remote manipulation

CEA-Marcoule-AtalantePhoto: Th. FOULON

CEA-Cadarache-Chicade Photo: E. Joly


Internal exposure risksInternal exposure risks

Internal exposureInternal exposure– The intake of radioactive substances can reach the

human organism through 4 different ways:» Inhalation, ingestion, skin absorption, wound

Concentration measurementConcentration measurement– Activity deposited on a filter (aerosol)– Circulation in a differential chamber (gas)

Exposure threshold (“mesure de tri”)Exposure threshold (“mesure de tri”)– when this threshold is exceeded, it is mandatory to

measure incorporation and to determine the committed effective dose

» Expressed in Bqhm-3

RS 814.501.43 Annex 10


Exposure measurementExposure measurement– The exposure is the integration of the concentration

of activity for a given time:» Exposure [Bqh/m3] = A(t) dt» Sampled activity [Bq] = Fs A(t) dt» Inhaled activity [Bq] = Fi A(t) dt

With Fs = sample flow, Fi = inhalation flow Example: the aerosols exposure can be

deduced from the activity deposited on a filter divided by the sample flow

Mixtures of radio nuclidesMixtures of radio nuclides– Example of additive rule for CA

Internal exposure risksInternal exposure risks

1<∑i

i

CAa

i


Working methodsWorking methods

General rules involving unsealed sourcesGeneral rules involving unsealed sources– Work should be conducted in a tray lined with

absorbent paper and at least in a fume cupboard– Use the smallest quantity of radioactivity compatible

with the objective of the experiment– Make a plan and test it if necessary– Know how to react in case of spill or a personal

contamination– Work carefully, and monitor regularly the work area

to avoid accidental contamination– All radioactive waste must be placed in marked

containers– Never work alone! Ask for RP supervision



ExampleExample– Sealed removal of waste or

material from glove box» Put the object in the bag» Check welding on a test

bag» 3 welds at close intervals» Cut in the middle one» Monitor gloves, scissors» Put the sealed object in a

second bag and weld it


Working methodsWorking methods Critical operationsCritical operations

– Caution: undressing (mask, overall and gloves removal)

– Combination of external and internal exposure: wearing heavy protections may extend the time of intervention

» Is there a benefit?– Small traps: glasses,

phone, watch, long hair...

CEA-Brennilis-Liquids Treatment Station Photo: A. Gonin



How to react in case of incidentHow to react in case of incident– Minor spills involving no radiation hazard to persons

» Confine the spill immediately» Notify all the other persons in the room» External decontamination

– Incidents with presumed incorporation» Vacate the room» Wear appropriate protection before re-entering

the room (for emergency measures)» External decontamination» Nasal sample, anthropogammametric scan (whole

body, thyroid), urine and/or feces analysis


““Frequently Asked Questions”Frequently Asked Questions”A few examples of radiation exposureA few examples of radiation exposure

Source: CEA

Documents

A. DORSIVALSAFERIB 20021 RADIATION PROTECTION IN A CLASS "A" TYPE LABORATORY SAFERIB 2002