SAFERIB 2002 RADIATION PROTECTION IN A CLASS "A" TYPE LABORATORY A. DORSIVAL SAFERIB 2002 1 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 A. DORSIVAL SAFERIB 2002 2 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) A. DORSIVAL SAFERIB 2002 3 The Swiss Ordinance  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 814.501 Annex 3, columns 10 The incorporation 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  A. DORSIVAL RS 814.501 Annex 3, columns 4 and 5 SAFERIB 2002 4 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  A. DORSIVAL RS 814.501 Annex 3, columns 12 SAFERIB 2002 5 The Swiss Ordinance : workplaces  Workplace classification Laboratory type Activity Class C 1 < LA < 100 Class B 1 < LA < 10000 Class A 1 < LA < upper permitted limit Activity used per operation and per day (RS 814.501 Article 69)  A. DORSIVAL SAFERIB 2002 6 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 A. DORSIVAL SAFERIB 2002 7 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) A. DORSIVAL Isolde release measurement SAFERIB 2002 8 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 A. DORSIVAL SAFERIB 2002 9 Class A laboratories : basic requirements CEA-Marcoule-Atalante Photos: Th. FOULON A. DORSIVAL SAFERIB 2002 10 External exposure risks  External exposure – Time, distance, shielding » Hot cells with lead-glass and remote manipulation CEA-Cadarache-Chicade Photo: E. Joly A. DORSIVAL SAFERIB 2002 CEA-Marcoule-Atalante Photo: Th. FOULON 11 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  A. DORSIVAL RS 814.501.43 Annex 10 SAFERIB 2002 12 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 A. DORSIVAL SAFERIB 2002  i ai 1 CAi 13 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 A. DORSIVAL SAFERIB 2002 14 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 A. DORSIVAL SAFERIB 2002 15 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 A. DORSIVAL SAFERIB 2002 16 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 A. DORSIVAL SAFERIB 2002 17 “Frequently Asked Questions” A few examples of radiation exposure Source: CEA A. DORSIVAL SAFERIB 2002 18