Protection of the public and the
environment
standards?
Rodolfo Avila
Outline
•
•
•
•
Risk - a probabilistic concept
How to quantify risks
The ICRP’s Representative Individual
Example: Assessments for High Level Waste
Repositories
• Standards
• Handling of uncertainties
Definition of Risk
• The word risk derives from the early
Italian “risicare” , which means to dare
• Risk is the "possibility of loss or injury:
peril.” (Webster Dictionary, 1999)
Decision under uncertainty
Ingredients:
• A partition of possible states of affairs
• The possible acts that the agent can
undertake
• The utilities of the consequences of each
possible act, in each possible state of affairs
of the partition
Le pari de Pascal
Pensees, 1660
God is, or he is not. Which way should you
incline?
”Reason cannot answer”
God is
God
is not
Devoted
+∞
0
Bohemian
-∞
0
Antoine Arnauld 1662
• Fear of harm ought to be proportional not
merely to the gravity of harm, but also to the
probability of the event
(”La logique, ou l´art de penser” a bestseller
at the time)
The concept of risk has (two) elements: the
likelihood of something happening and the
consequences if it happens
Expectation
• The expected value of an act is the sum of
the products
(Utilities x probabilities)
God is
God
is not
Expectation
Devoted
+
-
0/+/-
Bohemian
-∞
+
-∞
Dominance expected value rule
• In every admissible probability distribution,
one act has greater expected value than
every other act, then this act dominates the
others in expected value
If one act dominates the others in expected value
DO IT!
What is probability?
• The ancient Greek word  meant
plausible or probable. Socrates defined
it as ”likeness to truth”
• Probability is a measure of our
confidence that something is going to
happen. Probable means to be expected
with some degree of certainty
Conditional probabilities
• Any probability P(E) of an event E is
conditional to some stipulated model or
assumption (A1), it should strictly be written
P(E|A1), i.e. the probability of E, given A1.
• There may be other assumptions (A2, A3, A4,
… Ai) in addition to the assumption A1
believed to be the most likely.
How can this fact be taken into account?
”A priori” and ”a posteriori”
•
•
A priori probability- estimated before the
fact. Can be reliable ”only for the most part”
A posteriori probability- estimated after the
fact. By taking a sufficient large sample, you
can increase your confidence in the
estimated probability to whatever degree
you wish.
But, how reliable this probability is for
predicting future events?
Measuring Risk
• Risk is the probability that the Exposure is
above the Standard
• The Risk Quotient
RQ = Exposure/Standard
Releases
Contamination
From Releases to Harmful Effects
Exposure
of Man
Effects of
Man
Exposure
of biota
Effects on
biota
Representative individual - ICRP
• Since dose to the public cannot be measured directly, it
must be estimated using environmental concentrations and
appropriate habit data. Therefore, for the purpose of
protection of the public, it is necessary to define a
hypothetical exposed person to be used for determining
compliance with the dose constraint and for introduction of
a practice.
• This is the representative individual. The representative
individual is the hypothetical individual receiving a dose
that is representative of the most highly exposed
individuals in the population.
Dose Distribution
3
2.5
Dose constrain
2
1.5
1
0.5
0
0
0.625
1.25
1.875
2.5
Example HLW repository
The regulatory requirement
• One way of defining the most exposed group is to include
the individuals that receive a risk in the interval from the
highest risk down to a tenth of this risk. If a larger number
of individuals are considered to be included in such a
group, the arithmetic average of individual risks in the
group should be used for demonstrating compliance with
the criterion for individual risk in the regulations (i.e. 10-6
per year)….
• If the group only consists of a few individuals, the criterion
of the regulations of individual risks can be considered of
being complied with if the highest calculated individual
risk does not exceed 10-5 per year….
^
^^ ^
+^
+
^^
+
^
^
Lake
^^
+
Running
Water
^
^
Lake
^^ ^^^^
^^^^^
^^
^
^
Mire
Mire
^
^^
^
^^ ^^
^
^
^^
^
Lake
^
^^
^^^^
^
^^ ^
^^
^^
^
^^ ^^^^^
^^
^ ^
^^^^^^^^
^ ^
^^^ ^^
+
^^^^^^ ^^^^ ^^^ ^
^
^
^ ^^
^
Forest
0
0,5
^
^^
^^
Mire
^^
^ ^ ^^
^
Coast
^
^^
^^
^
^^^^
^^ ^ ^^
^^^
^^
^
Mire
^
^
^
^
^ ^^
^
^
^
^
^^^^ ^
^
^
^^^^^^^^^^^^^^^^^^^^^ ^^
^^^^ Coast
^ ^^^^^
^^^^
^
^^^^^^^
^^^ ^^^^^
1 km
^^^
^
^ ^^
Mire
^
^
^
^
^^^^^
^^
^^
^ ^^
^^ +
^
^
^
^
Mire
^^^
^^
^^
^^
^^
^^
^
^^
^
^^
^^
^^^ ^^^^^^
^ ^^
^^
^^ ^^^ ^^^^^^^
^^^
Dose Distribution
ID5 (0.1) mire
ID25 (0.1) runwat
6000
ID4 (4.1) coast
ID9 (78.6) agriland
ID14 (6.0) lake
ID8 (304.2) agriland
5000
ID6 (234.6) agriland
ID10 (226.7) agriland
ID13 (2.8) lake
23
ID24 (0.1) runwat
4000
ID7 (87.8) agriland
ID21 (145.1) agriland
N
ID18 (109.5) agriland
3000
2
3 22
ID26 (0.4) runwat
16
ID15 (141.6) agriland
ID12 (169.7) agriland
ID19 (88.4) agriland
17
2000
11
1000
20
19
12
1526
18
21
ID20 (279.1) agriland
ID11 (258.2) agriland
ID17 (763.9) agriland
ID16 (55.7) agriland
ID22 (0.0) runwat
7 2413
ID3 (82.9) coast
10
6
107
0
-14
10
ID2 (1070.0) coast
8 14
-13
10
-12
9
10
Dose, Sv/y per Bq/y
4
25
-11
10
ID23 (0.3) runwat
5
-10
10
max/10 (3e-012)
max (3e-011)
N (107)
Releases
Release rate
Contamination
Selecting the appropriate type of standard
Concentrations
Total releases Affected area
Exposure
of Man
Effects of
Man
Exposure
of biota
Effects on
biota
Dose rates, doses
probability of effects
Collective dose
number of effects
Measuring Risk with Probabilistic Standards
0.12
0.1
0.08
0.06
0.04
0.02
0
0
15
30
45
Measuring Risk
• Risk is the probability that the Exposure is
above the Standard
• The Risk Quotient
RQ = Exposure/Standard
Risk Profile
3
2.5
1
2
1.5
1
0.5
0
0
0.625
1.25
1.875
2.5
Protection of the public and the
environment
standards?
Rodolfo Avila
Outline
•
•
•
•
Risk - a probabilistic concept
How to quantify risks
The ICRP’s Representative Individual
Example: Assessments for High Level
Waste Repositories
• Standards
• Handling of uncertainties
Definition of Risk
• The word risk derives from the early
Italian “risicare” , which means to dare
• Risk is the "possibility of loss or injury:
peril.” (Webster Dictionary, 1999)
Decision under uncertainty
Ingredients:
• A partition of possible states of affairs
• The possible acts that the agent can
undertake
• The utilities of the consequences of each
possible act, in each possible state of affairs
of the partition
Le pari de Pascal
Pensees, 1660
God is, or he is not. Which way should you
incline?
”Reason cannot answer”
God is
God
is not
Devoted
+∞
0
Bohemian
-∞
0
Antoine Arnauld 1662
• Fear of harm ought to be proportional not
merely to the gravity of harm, but also to the
probability of the event
(”La logique, ou l´art de penser” a bestseller
at the time)
The concept of risk has (two) elements: the
likelihood of something happening and the
consequences if it happens
Expectation
• The expected value of an act is the sum of
the products
(Utilities x probabilities)
God is
God
is not
Expectation
Devoted
+
-
0/+/-
Bohemian
-∞
+
-∞
Dominance expected value rule
• In every admissible probability distribution,
one act has greater expected value than
every other act, then this act dominates the
others in expected value
If one act dominates the others in expected value
DO IT!
What is probability?
• The ancient Greek word  meant
plausible or probable. Socrates defined
it as ”likeness to truth”
• Probability is a measure of our
confidence that something is going to
happen. Probable means to be expected
with some degree of certainty
Conditional probabilities
• Any probability P(E) of an event E is
conditional to some stipulated model or
assumption (A1), it should strictly be written
P(E|A1), i.e. the probability of E, given A1.
• There may be other assumptions (A2, A3, A4,
… Ai) in addition to the assumption A1
believed to be the most likely.
How can this fact be taken into account?
”A priori” and ”a posteriori”
•
•
A priori probability- estimated before the
fact. Can be reliable ”only for the most part”
A posteriori probability- estimated after the
fact. By taking a sufficient large sample, you
can increase your confidence in the
estimated probability to whatever degree
you wish.
But, how reliable this probability is for
predicting future events?
Measuring Risk
• Risk is the probability that the Exposure is
above the Standard
• The Risk Quotient
RQ = Exposure/Standard
Releases
Contamination
From Releases to Harmful Effects
Exposure
of Man
Effects of
Man
Exposure
of biota
Effects on
biota
Representative individual - ICRP
• Since dose to the public cannot be measured directly, it
must be estimated using environmental concentrations and
appropriate habit data. Therefore, for the purpose of
protection of the public, it is necessary to define a
hypothetical exposed person to be used for determining
compliance with the dose constraint and for introduction of
a practice.
• This is the representative individual. The representative
individual is the hypothetical individual receiving a dose
that is representative of the most highly exposed
individuals in the population.
Dose Distribution
3
2.5
Dose constrain
2
1.5
1
0.5
0
0
0.625
1.25
1.875
2.5
Example HLW repository
The regulatory requirement
• One way of defining the most exposed group is to include
the individuals that receive a risk in the interval from the
highest risk down to a tenth of this risk. If a larger number
of individuals are considered to be included in such a
group, the arithmetic average of individual risks in the
group should be used for demonstrating compliance with
the criterion for individual risk in the regulations (i.e. 10-6
per year)….
• If the group only consists of a few individuals, the criterion
of the regulations of individual risks can be considered of
being complied with if the highest calculated individual
risk does not exceed 10-5 per year….
^
^^ ^
+^
+
^^
+
^
^
Lake
^^
+
Running
Water
^
^
Lake
^^ ^^^^
^^^^^
^^
^
^
Mire
Mire
^
^^
^
^^ ^^
^
^
^^
^
Lake
^
^^
^^^^
^
^^ ^
^^
^^
^
^^ ^^^^^
^^
^ ^
^^^^^^^^
^ ^
^^^ ^^
+
^^^^^^ ^^^^ ^^^ ^
^
^
^ ^^
^
Forest
0
0,5
^
^^
^^
Mire
^^
^ ^ ^^
^
Coast
^
^^
^^
^
^^^^
^^ ^ ^^
^^^
^^
^
Mire
^
^
^
^
^ ^^
^
^
^
^
^^^^ ^
^
^
^^^^^^^^^^^^^^^^^^^^^ ^^
^^^^ Coast
^ ^^^^^
^^^^
^
^^^^^^^
^^^ ^^^^^
1 km
^^^
^
^ ^^
Mire
^
^
^
^
^^^^^
^^
^^
^ ^^
^^ +
^
^
^
^
Mire
^^^
^^
^^
^^
^^
^^
^
^^
^
^^
^^
^^^ ^^^^^^
^ ^^
^^
^^ ^^^ ^^^^^^^
^^^
Dose Distribution
ID5 (0.1) mire
ID25 (0.1) runwat
6000
ID4 (4.1) coast
ID9 (78.6) agriland
ID14 (6.0) lake
ID8 (304.2) agriland
5000
ID6 (234.6) agriland
ID10 (226.7) agriland
ID13 (2.8) lake
23
ID24 (0.1) runwat
4000
ID7 (87.8) agriland
ID21 (145.1) agriland
N
ID18 (109.5) agriland
3000
2
3 22
ID26 (0.4) runwat
16
ID15 (141.6) agriland
ID12 (169.7) agriland
ID19 (88.4) agriland
17
2000
11
1000
20
19
12
1526
18
21
ID20 (279.1) agriland
ID11 (258.2) agriland
ID17 (763.9) agriland
ID16 (55.7) agriland
ID22 (0.0) runwat
7 2413
ID3 (82.9) coast
10
6
107
0
-14
10
ID2 (1070.0) coast
8 14
-13
10
-12
9
10
Dose, Sv/y per Bq/y
4
25
-11
10
ID23 (0.3) runwat
5
-10
10
max/10 (3e-012)
max (3e-011)
N (107)
Releases
Release rate
Contamination
Selecting the appropriate type of standard
Concentrations
Total releases Affected area
Exposure
of Man
Effects of
Man
Exposure
of biota
Effects on
biota
Dose rates, doses
probability of effects
Collective dose
number of effects
Measuring Risk with Probabilistic Standards
0.12
0.1
0.08
0.06
0.04
0.02
0
0
15
30
45
Measuring Risk
• Risk is the probability that the Exposure is
above the Standard
• The Risk Quotient
RQ = Exposure/Standard
Risk Profile
3
2.5
1
2
1.5
1
0.5
0
0
0.625
1.25
1.875
2.5