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RADIATION PROTECTION IN A CLASS "A" TYPE LABORATORY

RADIATION PROTECTION IN A CLASS "A" TYPE LABORATORY. SAFERIB 2002. Overview. Regulations A few definitions, guidelines and limits extracted from the Swiss ordinance ORaP Workplace equipment What are the basic equipments in a class A type laboratory Exposure risks

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RADIATION PROTECTION IN A CLASS "A" TYPE LABORATORY

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  1. RADIATION PROTECTIONIN A CLASS "A" TYPE LABORATORY SAFERIB 2002 SAFERIB 2002

  2. Overview • Regulations • A few definitions, guidelines and limits extracted from the Swiss ordinance ORaP • Workplace equipment • What are the basic equipments in a class A type laboratory • Exposure risks • How to measure and reduce external and internal radiation exposure SAFERIB 2002

  3. Vocabulary • 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 • 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) SAFERIB 2002

  4. The Swiss Ordinance • Thelicensing 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 • Theincorporation dose factors “einh” and “eing” • 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 SAFERIB 2002

  5. The Swiss Ordinance: guideline values • 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” • 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 SAFERIB 2002

  6. The Swiss Ordinance : workplaces • Workplace classification • Activity used per operation and per day (RS 814.501 Article 69) SAFERIB 2002

  7. Class A laboratories :basic requirements • General characteristics • Located away from circulation • Isolated from other workplaces • Grouped to form a unit (controlled area) • Hierarchically organized following risks • Ventilation • Minimum air renewal : 5 h-1 • Hierarchic depression • “Absolute” filtration • Release chimney • Control system (radioactivity, flows, pressures…) • Backup power supply SAFERIB 2002

  8. Isolde release measurement Class A laboratories :basic requirements • Radioactive storage area • Low background for contamination measurements • External exposure reduction • Radioactive release management • Gas and aerosol monitoring • Liquids monitoring (backup reservoir) SAFERIB 2002

  9. Class A laboratories :basic requirements • 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 • Working clothes (overall, gloves, special shoes or overshoes…) • Breathing protection device SAFERIB 2002

  10. Class A laboratories :basic requirements CEA-Marcoule-Atalante Photos: Th. FOULON SAFERIB 2002

  11. External exposure risks • 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 SAFERIB 2002

  12. Internal exposure risks • Internal exposure • The intake of radioactive substances can reach the human organism through 4 different ways: • Inhalation, ingestion, skin absorption, wound • Concentration measurement • Activity deposited on a filter (aerosol) • Circulation in a differential chamber (gas) • 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 SAFERIB 2002

  13. Internal exposure risks • 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] = 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 nuclides • Example of additive rule for CA SAFERIB 2002

  14. Working methods • 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 SAFERIB 2002

  15. Working methods • 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 SAFERIB 2002

  16. Working methods • 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 SAFERIB 2002

  17. Working methods • 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 SAFERIB 2002

  18. “Frequently Asked Questions” A few examples of radiation exposure Source:CEA SAFERIB 2002

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