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

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Presentation on theme: "A. DORSIVALSAFERIB 20021 RADIATION PROTECTION IN A CLASS "A" TYPE LABORATORY SAFERIB 2002."— Presentation transcript:

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

2 A. DORSIVALSAFERIB Regulations Regulations – –A few definitions, guidelines and limits extracted from the Swiss ordinance ORaP Workplace equipment Workplace equipment – –What are the basic equipments in a class A type laboratory Exposure risks Exposure risks – –How to measure and reduce external and internal radiation exposure Overview

3 A. DORSIVALSAFERIB Vocabulary Unsealed source Unsealed 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 contamination Radioactive 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)

4 A. DORSIVALSAFERIB The Swiss Ordinance The licensing limit “LA” The 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 Annex 3, columns 10 The incorporation dose factors “ e inh ” and “ e ing ” The incorporation dose factors “ e inh ” and “ e ing ” – –For the considered isotope, the inhalation or respectively ingestion of 1 Bq causes the given effective dose » »Source: Directive Euratom 96/29 RS Annex 3, columns 4 and 5

5 A. DORSIVALSAFERIB The 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 Annex 3, columns 11 The surface contamination “CS” The surface contamination “CS” – –Expressed in Bq/cm 2, this guideline value is the most conservative result of 3 calculation modes and applies for material leaving controlled areas: » »Skin irradiation, Ingestion, Inhalation RS Annex 3, columns 12

6 A. DORSIVALSAFERIB The Swiss Ordinance : workplaces Workplace classification Workplace classification Activity used per operation and per day (RS Article 69) Laboratory type Activity Class C 1 < LA < 100 Class B 1 < LA < Class A 1 < LA < upper permitted limit

7 A. DORSIVALSAFERIB Class A laboratories : basic requirements General characteristics General characteristics – –Located away from circulation – –Isolated from other workplaces – –Grouped to form a unit (controlled area) – –Hierarchically organized following risks Ventilation Ventilation – –Minimum air renewal : 5 h -1 – –Hierarchic depression – –“Absolute” filtration – –Release chimney – –Control system (radioactivity, flows, pressures…) – –Backup power supply

8 A. DORSIVALSAFERIB Class A laboratories : basic requirements Radioactive storage area Radioactive storage area – –Low background for contamination measurements – –External exposure reduction Radioactive release management Radioactive release management – –Gas and aerosol monitoring – –Liquids monitoring (backup reservoir) Isolde release measurement

9 A. DORSIVALSAFERIB Collective equipment Collective equipment – –Fume cupboards (dynamic confinement) – –Glove box (static confinement) – –Appropriate radiation protection monitors – –Radioactive waste containers – –Decontamination facilities – –“Hot and cold” changing rooms Individual equipment Individual equipment – –Working clothes (overall, gloves, special shoes or overshoes…) – –Breathing protection device Class A laboratories : basic requirements

10 A. DORSIVALSAFERIB Class A laboratories : basic requirements CEA-Marcoule-Atalante Photos: Th. FOULON

11 A. DORSIVALSAFERIB External exposure risks External exposure External exposure – –Time, distance, shielding » »Hot cells with lead-glass and remote manipulation CEA-Marcoule-Atalante Photo: Th. FOULON CEA-Cadarache-Chicade Photo: E. Joly

12 A. DORSIVALSAFERIB Internal exposure risks Internal exposure Internal exposure – –The intake of radioactive substances can reach the human organism through 4 different ways: » »Inhalation, ingestion, skin absorption, wound Concentration measurement Concentration 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 Annex 10

13 A. DORSIVALSAFERIB Exposure measurement Exposure measurement – –The exposure is the integration of the concentration of activity for a given time: » »Exposure [Bqh/m3] =  A(t) dt » »Sampled activity [Bq] = F s  A(t) dt » »Inhaled activity [Bq] = F i  A(t) dt With F s = sample flow, F i = inhalation flow Example: the aerosols exposure can be deduced from the activity deposited on a filter divided by the sample flow Mixtures of radio nuclides Mixtures of radio nuclides – –Example of additive rule for CA Internal exposure risks

14 A. DORSIVALSAFERIB Working methods General rules involving unsealed sources General 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

15 A. DORSIVALSAFERIB Working methods Example Example – –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

16 A. DORSIVALSAFERIB Working methods Critical operations Critical 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

17 A. DORSIVALSAFERIB Working methods How to react in case of incident How 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

18 A. DORSIVALSAFERIB “Frequently Asked Questions” A few examples of radiation exposure Source: CEA


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