18/04/23 radiation safety - level 5 1

Radiation safetyRadiation safetylevel 5level 5

Frits Pleiter

18/04/23 radiation safety - level 5 2

ContentsContents

atomic and nuclear physics (1) interaction with matter (3)

o sources and x-ray equipment (2)o shielding (3)o detection (4)o radiobiology (6)

• objective risk of radiation (6)• subjective risk acceptation (6)

quantities and units (5) regulations (7)

o practical health physics (8 - 10)o waste (11)

18/04/23 radiation safety - level 5 3

DosimetryDosimetrysource constant and inverse square lawsource constant and inverse square law

dose is proportional to the activity and to the irradiation timedose decreases with the square of the distance from the source

D = A t / r2

the constant in this equation is called "source constant"it makes it possible to convert activity to external dose

E / 7 Gy m2 MBq-1 h-1 (E in MeV)

18/04/23 radiation safety - level 5 4

DosimetryDosimetrysource constant and inverse square lawsource constant and inverse square law

nuclide (Gy m2 MBq-1 h-1) T½22Na 0.33 2.6 j60Co 0.36 5.3 j99mTc 0.023 6.0 h125I 0.034 60 d131I 0.066 8.0 d137Cs 0.093 30 j192Ir 0.14 74 d201Tl 0.017 73 h241Am 0.017 430 j

18/04/23 radiation safety - level 5 5

DosimetryDosimetryrules of thumbrules of thumb

at 1 m from a -source of 1 MBq dose rate 10 µGy/h

at 1 m from a -source of 1 MBq dose rate E / 7 µGy/h

at 1 m from an x-ray tube dose rate 10 mGy/min

a -contamination of 1 kBq per cm2

skin dose rate rate 2 mGy/h

18/04/23 radiation safety - level 5 6

DosimetryDosimetryeffective dose coefficienteffective dose coefficient

E(50) = e(50) A

the "effective dose coefficient" e(50) depends onradiotoxicity of the nuclidechemical composition of the radioactive substancecontamination route (ingestion, inhalation, injection, wound, skin)

it makes it possible to convert activity to internal doseespecially tritiated water can penetrate skin and even gloves

18/04/23 radiation safety - level 5 7

DosimetryDosimetryeffective dose coefficienteffective dose coefficient

nuclide e(50)inh (Sv/Bq) T½3H (H2O) 1.810-11 12.3 j14C (CO2) 6.510-12 5730 j22Na 2.010-9 2.6 j32P 2.910-9 14.3 d35S 1.210-10 87.5 d45Ca 2.310-9 163 d99mTc 2.910-11 6.0 h125I 7.310-9 60 d131I 1.110-8 8.0 d226Ra 1.210-5 1600 jnatural Th 6.210-5 1.41010 jnatural U 5.710-5 4.5109 j

18/04/23 radiation safety - level 5 8

Safety measuresSafety measuresnominal working hoursnominal working hours

8 hours per day5 days per week 40 hours per week50 weeks per year 2000 hours per year

18/04/23 radiation safety - level 5 9

Safety measuresSafety measuresorganisational measuresorganisational measures

maintain a correct administration system for sources and devicesmark each source and device with a warning sign when in usestore unused sources in a vaultremove the key of an x-ray device when not in use

18/04/23 radiation safety - level 5 10

Safety measuresSafety measuressealed sourcessealed sources

protection against external radiationuse as little activity as possible (ALARA)reduce exposure timeincrease working distance (inverse square law)apply shielding (lead, lucite)measure the dose rate

periodic leak testtake regular smear tests (limit is 185 Bq)direct activity measurent with a contamination monitor is pointless

18/04/23 radiation safety - level 5 11

Safety measuresSafety measuresx-ray devicesx-ray devices

protection against external radiationdo not irradiate more often than necessary (ALARA)reduce exposure timeincrease working distance (inverse square law)apply shielding (lead apron)use a dose rate meter that is sensitive at low energy

check the equipment periodicallycheck filter and leakage radiationleave maintenance to the supplier of the equipment

watch out for scattered radiationreduce exposed area (diaphragm, light visor)

18/04/23 radiation safety - level 5 12

Safety measuresSafety measuresopen radioactive substancesopen radioactive substances

protection against external radiationsee sealed sources

protection against internal contaminationuse as little activity as possible (ALARA)prevent spreading (containment, splash tray)remove air born activity (ventilation, fume hood)prevent intake of activity (work discipline, protocol)

check for contamination by periodic laboratory surveysimmediately warn responsible radiation expertevacuate laboratory and check workers when leavingdetermine extent of contamination (dose rate meter is useless)decontaminated surface (limit is 4 Bq/cm2)

18/04/23 radiation safety - level 5 13

Safety measuresSafety measuresopen radioactive substancesopen radioactive substances

principle of "containment"glas tube, beaker glas, splash tray, fume hood, radionuclide laboratory

18/04/23 radiation safety - level 5 14

Safety measuresSafety measuresopen radioactive substancesopen radioactive substances

avoid oral uptakedon't eat at the work placedon't drink at the work placedon't smoke at the work placedon't apply make-up at the work place

18/04/23 radiation safety - level 5 15

Safety measuresSafety measuresopen radioactive substancesopen radioactive substances

avoid uptake via lungsrisk of aerosol formation while

shaking and vortexingcentrifugingopening bottlessanding

risk of tritium vapourtritium in condens is released when defrosting a refrigerator

risk of iodine vapouravoid formation of iodine vapour (keep pH > 4)iodine in condens is released when warming up a "cold room"keep lid on waste bin

18/04/23 radiation safety - level 5 16

Safety measuresSafety measuresopen radioactive substancesopen radioactive substances

avoid direct uptake in blood systemdon't work with open woundsavoid uptake of 3H via skin (use double gloves)

18/04/23 radiation safety - level 5 17

Radionuclide laboratoryRadionuclide laboratoryregulationsregulations

work with open radioactive substances is only permitted in a radionuclide laboratory

there are B-, C- en D-laboratories

building requirements are most stringent for a B-laboratorybuilding requirements are least stringent for a D-laboratory

maximum allowed activity is largest in a B-laboratorymaximum allowed activity is smallest in a D-laboratory

18/04/23 radiation safety - level 5 18

Radionuclide laboratoryRadionuclide laboratoryguideline radionuclide laboratoriesguideline radionuclide laboratories

there are two different opinions1.the risk is determined by regular uptake of small quantities of radioactive substances (National Health Council, 1985)2.the risk is determined by incidents (HARAS-report, 1997)

the Guideline Radionuclide Laboratories is based on opinion 1

18/04/23 radiation safety - level 5 19

Radionuclide laboratoryRadionuclide laboratoryguideline radionuclide laboratoriesguideline radionuclide laboratories

Amax = 0.02 10 p+q+r / e(50)inh

Amax = maximum allowed activity in Bqp = dispersion parameterq = laboratory parameterr = local ventilation parameter (note that r q)e(50) = dose conversion coefficient in Sv/Bq

18/04/23 radiation safety - level 5 20

Radionuclide laboratoryRadionuclide laboratoryguideline radionuclide laboratoriesguideline radionuclide laboratories

p application

-4 highly splashing substancepowder in open system

-3 labelling using volatile nuclideboiling liquid in closed system

-2 labelling using nonvolatile nuclidesimple chemical work (RIA)

-1 short, very simple work with liquidstorage of waste in working area

18/04/23 radiation safety - level 5 21

Radionuclide laboratoryRadionuclide laboratoryguideline radionuclide laboratoriesguideline radionuclide laboratories

q work place

0 outside radionuclide laboratory

1 D-laboratoryancillary space of radionuclide laboratory

2 C-laboratory

3 B-laboratory

18/04/23 radiation safety - level 5 22

Radionuclide laboratoryRadionuclide laboratoryguideline radionuclide laboratoriesguideline radionuclide laboratories

r local ventilation

0 no ventilation

1 fume hood (not NEN-NE 14175)

2 fume hood (NEN-NE 14175)

3 closed system (glove box)

18/04/23 radiation safety - level 5 23

RegulationsRegulationsradioactive wasteradioactive waste

radioactive waste is waste in whichboth the activity concentration exceeds the exemption leveland the activity exceeds the exemption level

radioactive waste is also waste that looks like radioactive waste no radioactivity stickers in normal industrial waste

disposal is expensive (in 2005 about € 1300 per 100 liter)

only COVRA is allowed to collect radioactive waste

18/04/23 radiation safety - level 5 24

RegulationsRegulationsrradioactive wasteadioactive waste

avoid waste productionuse as little activity as possibleuse short-lived nuclidesif not active, dispose as normal industrial waste

separate wastedry and liquid wasteorganic and inorganic wastelong-lived and short-lived wastecounting vialscadaverssealed sources

hand waste over to COVRA in standard drums

18/04/23 radiation safety - level 5 25

RegulationsRegulationsradioactive wasteradioactive waste

radioactive substances may be handed over to another person provided

either the activitity concentration is less than the exemption levelor the activity is less than the exemption level

18/04/23 radiation safety - level 5 26

RegulationsRegulationsradioactive wasteradioactive waste

nuclide concentration (Bq/g) activity (Bq)3H 106 109

14C 104 107

32P 103 106

35S 105 108

99mTc 102 107

125I 103 106

131I 102 106

226Ra 1 104

238U 10 104

18/04/23 radiation safety - level 5 27

RegulationsRegulationsdisposaldisposal

there are strict rules fordischarge to airdischarge to sewerdose rate at border of the location

knowledge of these rules is not required for the course level 5