ALARA and Occupational Exposures: Experience and Challenges 27/04/2019 ALARA and Occupational Exposures: Experience and Challenges J. Lochard ISOE International ALARA Symposium Tsugura, Japan, 13-14 November 2008

Content of the presentation 27/04/2019 Content of the presentation ALARA and the quest for reasonable : an historical perspective From ICRP 60 to ICRP 103 Trends in occupational exposures Radiation risk at the workplace in perspective Concluding remarks

First stage: prudence Recognition of stochastic effects in the late 40s "Taking into account uncertainties about the risk and the irreversibility of the effects, it is prudent to reduce exposures to the lowest possible level" (ICRP-1950) The limit is not anymore a guarantee of the absence of risk

Second stage : justification In a context of uncertainty taking a risk is justified only if their is a benefit in return If there is a benefit How far to reduce the risk without endanger the activity? As low as practicable (ICRP 1-1958) On which criteria to ground the decision?

Third phase: economic and social considerations Recommendation to keep exposures as low as readily achievable, economic and social considerations being taken into account (ICRP 9 -1965) The reduction of risk must be compared with the effort to achieve it Need of quantification for practical application

ALARA: balancing costs and benefits The adverb ‘readily’ is replaced by ‘reasonably’ (ICRP 22 -1973) Introduction of the cost-benefit model The decision process is reduced to a few parameters and focused on the avoided dose Attempt to integrate social values in the quantitative framework (ICRP 37-1983)

Evolution of the ALARA principle wording

Beyond the cost-benefit model ICRP 55 - 1988: Return to a more pragmatic approach: the ALARA Procedure ICRP 60 - 1990: Need to consider "the magnitude of individual exposures, the number of people exposed and the likelihood of incurring exposures where these are not certain to be perceived (= potential exposures)"in the optimisation process Equity issue and the tolerability of risk model Introduction of the dose constraint concept for practices to limit the range of options considered in the optimisation process

The tolerability of risk model Individual dose level Unacceptable risk Dose limit Tolerable risk Optimisation process ALARA level Acceptable residual risk

ICRP 101- 2005: broadening the process Optimisation of protection is a forward-looking process aimed at preventing exposure before they occur Optimisation is a frame of mind always questioning whether the best has been done in the prevailing circumstances Consolidation of the previous publications and broadening the process "to reflect the increasing role of individual equity, safety culture, and stakeholder involvement"

The ICRP 60 system of protection (1) Practices Justification, optimisation, limitation (except for medical exposures) Dose limits Individual dose constraints Interventions Justification, optimisation Intervention levels

The ICRP 60 system of protection (2) Practices Interventions "generic" optimisation Dose limit Dose constraint Action/intervention level Optimisation

The ICRP 103 system of protection (1) Planned exposure situations: situations involving the deliberate introduction and operation of sources. Justification, optimisation with dose constraints, dose limits (except medical exposures) Emergency exposure situations: situations that may occur during the operation of a planned situation, or from a malicious act, or from any other unexpected situation, and require urgent action in order to avoid or reduce undesirable consequences. Justification, optimisation with reference levels Existing exposure situations: exposure situations that already exist when a decision on control has to be taken, including prolonged exposure situations after emergencies

The ICRP 103 system of protection (2) Planned exposure situations Emergency and existing exposure situations Dose limit Reference level Dose constraint Optimisation Optimisation

The individual levels of protection Dose limits Dose constraints and reference levels Protect individuals from public and occupational exposure… from all regulated sources, in planned exposure situations from a source, in all exposure situations

Dose ranges in ICRP 103 for dose constraints and reference levels (1) Band of constraint or reference level Characteristics Greater than 20 to 100 mSv Individuals exposed by sources that are not controllable, or where actions to reduce doses would be disproportionately disruptive. Exposures are usually controlled by action on the exposure pathways. Greater than 1 to 20 mSv Individuals will usually receive benefit from the exposure situation but not necessarily from the exposure itself. Exposures may be controlled at source or, alternatively, by action in the exposure pathways. 1 mSv or less Individuals are exposed to a source that gives them little or no individual benefit but benefits to society in general. Exposures are usually controlled by action taken directly on the source for which radiological protection requirements can be planned in advance.

Dose ranges in ICRP 103 for dose constraints and reference levels (2) Band of constraint or reference level Examples Greater than 20 to 100 mSv Reference level set for the highest planned residual dose from a radiological emergency : 100 mSv Greater than 1 to 20 mSv Constraints set for occupational exposure in planned situations Constraints set for comforters and carers of patients treated with radiopharmaceuticals Reference level for the highest planned residual dose from radon in dwellings Reference level for existing situation resulting from accidents: residual dose of 1 mSv/year 1 mSv or less Constraints set for public exposure in planned situations

The concept of dose constraint The concept of dose constraint is used in conjunction with the optimisation of protection A dose constraint is a source-related restriction on the individual dose from a source used prospectively in planned exposure situations which serves as an upper bound in the optimisation of protection from that source The term “source” refers to any physical entity or procedure that results in a potentially quantifiable radiation dose to a person or group of persons Dose constraints are defined at the design stage using past experience

Constraints and planned exposure situations Occupational exposure Usually set by operator Small operators may need guidance from regulator Transient/itinerant workers need special attention Public exposure Usually set by regulator

The tolerability of risk model Individual dose level Unacceptable risk Dose limit Tolerable risk Dose constraint Optimisation process ALARA level Acceptable residual risk

Occupational exposure: number of monitored workers (UNSCEAR 2008) 27/04/2019 Occupational exposure: number of monitored workers (UNSCEAR 2008) Source 1975-79 1980-84 1985-89 1990-94 1995-99 2000-02 Number of monitored workers (thousands) Natural radiation 6 500 11 550 Nuclear fuel cycle 560 800 888 670 660 Medical uses 1 280 1 890 2 220 2 320 2 442 2 592 Industrial uses 530 690 700 790 869 Military activities 310 350 400 420 378 331 Miscella. 140 180 160 360 476 565 Total 2 820 3 910 4 228 11 100 (4 600)* 16 360 (4 756)* 16 567 (5 017)* Miscellaneous: educational establishment, veterinary medicine, transport… * Without natural radiation (NORMs)

Occupational exposure: annual collective dose (UNSCEAR 2008) 27/04/2019 Occupational exposure: annual collective dose (UNSCEAR 2008) Source 1975-79 1980-84 1985-89 1990-94 1995-99 2000-02 Annual collective effective dose (man.Sv) Natural radiation 11 700 27 500 Nuclear fuel cycle 2 300 3 000 2 500 1 400 1 000 800 Medical uses 1 140 1 030 760 803 850 Industrial uses 870 940 510 360 315 289 Military activities 420 250 100 52 45 Miscella. 70 40 20 53 56 Total 4 660 5 370 4 310 14 360 (2 660)* 29 723 (2 223)* 29 540 (2 040)* NORM (coal mining activities). Within 2000-2002, NORM = 93% of total reported collective exposure. Linked to mining activities. Medical sector / nuclear industry: almost the same collective dose. Large decrease of military activities collective dose. Attention must be paid to miscellaneous activities. Miscellaneous: educational establishment, veterinary medicine, transport… * Without natural radiation (NORMs)

Occupational exposure : annual average dose (UNSCEAR 2008 ) 27/04/2019 Occupational exposure : annual average dose (UNSCEAR 2008 ) Source 1975-79 1980-84 1985-89 1990-94 1995-99 2000-02 Annual average effective dose (mSv) Natural radiation 1,8 2,4 Nuclear fuel cycle 4,4 3,7 2,6 1,4 1,0 Medical uses 0,8 0,6 0,5 0,3 Industrial uses 1,6 0,9 0,4 Military activities 1,3 0,7 0,2 0,1 Miscella. Total 1,7 (0,6)* (0,5)* (0,4)* Highest average individual dose: NORMs. When analyzing average individual dose, attention should be paid to the distribution of individual doses and to the way it is calculated - taking or not into account all monitored workers -. Miscellaneous: educational establishment, veterinary medicine, transport… * Without natural radiation (NORMs)

Occupational exposure: distribution of individual doses (ESOREX) 27/04/2019 Occupational exposure: distribution of individual doses (ESOREX) Dose range Medical Industry NPP NORM < 0,1 353 553 44 953 45 324 762 0,1 - 0,2 22 450 6 066 11 375 591 0,2 - 0,5 36 288 5 824 16 843 1 190 0,5 - 1,0 31 194 4 709 7 973 2 551 1,0 - 2,0 11 549 3 267 6 197 11 188 2,0 - 5,0 7 333 5 962 11 073 10 714 5,0 - 10,0 2 058 1 369 1 529 653 10,0 - 15,0 928 1 412 1 545 80 15,0 - 20,0 311 104 141 32 20,0 - 50,0 384 53 45 23 > 50,0 30 8 2 Data from ESOREX website. Stephan Mundigl has been contacted and may provide further elements (country profiles). Highest individual exposures: medical sectors. Interesting distribution of NORM individual exposures. Study on Occupational Radiation Exposure of Workers in Europe, ESOREX 2005 K. Petrova, G. Frasch, K. Schnuer, S. Mundigl

Occupational exposure in the nuclear fuel cycle (UNSCEAR 2008) 27/04/2019 Occupational exposure in the nuclear fuel cycle (UNSCEAR 2008) Period Monitored workers (thousands) Average annual Collective dose (man.Sv) Annual effective dose (mSv) NR15 1975 - 1979 560 2300 4,4 0,63 1980 - 1984 800 3000 3,7 - 1985 - 1989 880 2500 2,8 0,42 1990 - 1994 1400 1,8 0,11 1995 - 1999 700 1000 1,4 0,07 2000 - 2002 660 1,2 Continuous decrease of the annual individual effective dose and NR15. Detailed data for each step of the nuclear fuel cycle are available (see the end of the .ppt file) as well as graphics in the 2 following slides. NR15: fraction of workers with effective dose higher than 15 mSv.

Risk associated with ionising radiation - Adult workers - 27/04/2019 Risk associated with ionising radiation - Adult workers - Detriment per sievert Cancers 4.1 x 10-2 Heritable effects 0,1 x 10-2 Total 4,2 x 10-2 ICRP 103 (2007) Assuming 25 years at work at the limit of 20 mSv the lifetime risk of developing a cancer is increased by 2 %

Occupational exposures in electricity generation (PWR) 27/04/2019 Occupational exposures in electricity generation (PWR) Period Monitored workers (thousands) Annual Collective dose (man.Sv) Annual effective dose (mSv) 1975 - 1979 63 220 3,5 1980 - 1984 140 450 3,1 1985 - 1989 230 500 2,2 1990 - 1994 310 415 1,3 1995 - 1999 265 506 1,9 2000 - 2002 283 1,7 Source: UNSCEAR 2008

Annual risk associated with the average exposure in PWRs 27/04/2019 Annual risk associated with the average exposure in PWRs Annual risk associated with 1.7 mSv (late cancer after exposure using ICRP 103 coefficient): D = 1,7.10-3*4,2*10-2 = 7,14.10-5 Annual risk of lethal occupational accident (immediate death): France: 2.86.10-5 (2005), USA: 4.10-5 (2006).

27/04/2019 Detriment associated to radiation exposure and annual risk of fatal occupational injury 3,5 mSv 3,1 mSv 2,2 mSv 1,9 mSv 1,7 mSv 1,3 mSv

Radiation risk in perspective 27/04/2019 Radiation risk in perspective The average level of radiation risk in the workplace is in the same order of magnitude than other risks for workers The upper exposure levels, particularly those close to the limits, are significantly deviating from the main trends as far as quantitative risk estimate is concerned Need to pursue efforts to reduce further the exposure of the most exposed workers in all domains = systematic implementation of ALARA

The way forward for further improvements in occupational radiation protection Engaging a reflection on potential exposures (use of incident data basis) Developing ALARA procedures and tools for dismantling operations Sharing experience to diffuse the use of dose constraints Enhancing radiation protection culture Strengthening existing ALARA networks Favouring stakeholders engagement in the decision making process A remaining issue: the situation of transient workers

ALARA and dismantling in France 27/04/2019 ALARA and dismantling in France The first dismantling operations at French nuclear installations and NPPs have shown: A lack of ALARA culture, notably at the level of the formalisation of the process A weakness of dose estimations for the preparation of the work A lack of reactivity of the teams when the first data become available at the beginning of the operations Missing records concerning the description of the installations and their life time history The non adaptation of "classical" technical procedures used for operation and maintenance The lack of commitment and engagement of all concerned parties

The way forward for further improvements in occupational radiation protection Engaging a reflection on potential exposures (use of incident data basis) Developing ALARA procedures and tools for dismantling operations Sharing experience to diffuse the use of dose constraints Enhancing radiation protection culture Strengthening existing ALARA networks Favouring stakeholders engagement in the decision making process A remaining issue: the situation of transient workers