1. ALARA and Occupational Exposures: Experience and Challenges
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ALARA and Occupational Exposures: Experience and Challenges
J. Lochard
ISOE International ALARA Symposium
Tsugura, Japan, November 2008

2. Content of the presentation
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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

3. 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

4. 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 )
On which criteria to ground the decision?

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

6. ALARA: balancing costs and benefits
The adverb ‘readily’ is replaced by ‘reasonably’ (ICRP )
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 )

7. Evolution of the ALARA principle wording

8. Beyond the cost-benefit model
ICRP : Return to a more pragmatic approach: the ALARA Procedure
ICRP :
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

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

10. 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"

11. 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

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

13. 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

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

15. 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

16. 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.

17. 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

18. 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

19. 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

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

21. Occupational exposure: number of monitored workers (UNSCEAR 2008)
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Occupational exposure: number of monitored workers (UNSCEAR 2008)
Source
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)

22. Occupational exposure: annual collective dose (UNSCEAR 2008)
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Occupational exposure: annual collective dose (UNSCEAR 2008)
Source
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 , 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)

23. Occupational exposure : annual average dose (UNSCEAR 2008 )
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Occupational exposure : annual average dose (UNSCEAR 2008 )
Source
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)

24. Occupational exposure: distribution of individual doses (ESOREX)
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Occupational exposure: distribution of individual doses (ESOREX)
Dose range
Medical
Industry
NPP
NORM
< 0,1
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

25. Occupational exposure in the nuclear fuel cycle (UNSCEAR 2008)
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Occupational exposure in the nuclear fuel cycle (UNSCEAR 2008)
Period
Monitored workers (thousands)
Average annual Collective dose (man.Sv)
Annual effective dose (mSv)
NR15
560
2300
4,4
0,63
800
3000
3,7 -
880
2500
2,8
0,42
1400
1,8
0,11
700
1000
1,4
0,07
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.

26. Risk associated with ionising radiation - Adult workers -
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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 %

27. Occupational exposures in electricity generation (PWR)
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Occupational exposures in electricity generation (PWR)
Period
Monitored workers (thousands)
Annual Collective dose (man.Sv)
Annual effective dose (mSv) 63
220
3,5
140
450
3,1
230
500
2,2
310
415
1,3
265
506
1,9
283
1,7
Source: UNSCEAR 2008

28. Annual risk associated with the average exposure in PWRs
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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,
Annual risk of lethal occupational accident (immediate death):
France: (2005),
USA: (2006).

29. 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

30. Radiation risk in perspective
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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

31. 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

32. ALARA and dismantling in France
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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

33. 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