Assessing Prolonged Exposures. The DRL Approach

Assessing Prolonged Exposures.The DRL Approach

Assessing Prolonged Exposures.The DRL Approach

National Institute for Physics and Nuclear Engineering, Bucharest, RomaniaDepartment of Life- and Environmental Physics

Bogdan Vamanu, MScValentin Acasandrei, MScDan Vamanu, PhD

8th Meeting of the EMRAS Tritium & C-14 Working GroupMay 30 - June 1, 2007 - Bucharest, Romania

Bogdan Vamanu, NIPNE, Romania EMRAS 2007 Spring Meeting, May 30 - June 1, 2007, Bucharest, Romania

routine (tehnologically-normal) environmental releases resulting in prolonged exposures of the radiation workers (onsite) and the

population (outside)

SITINGSITING

SITINGAUTHORIZATION

SITINGMONITORING


The DRL is defined as the radioactive release over a year that would exposemembers of the critical group to the regulatory dose limit. In general, nuclear power plants set their operating targets for releases of each radionuclide below 1% of the DRL.

Technical Reports Series No. 42IManagement of Waste Containing Tritium and Carbon-14 - IAEA

radioactive release over a yearcritical group

releases of each radionuclide below 1% of the DRLregulatory dose limit


Derived Release Limit (DRL): A limit imposed by the AECB on the release of a radioactive substance from a licensed nuclear facility such that compliance with the DRL gives reasonable assurance that the regulatory dose limit is not exceeded.

Radioactive Release Data from Canadian Nuclear Generating Stations 1990 to 1999. INFO-0210/REV. 10

Canadian Nuclear Safety Commission, October 2000

A limit imposedlicensed nuclear facility

reasonable assurance


From 2002 to 2004, the annual public dose was calculated using emissions to air and emissions to sewer in a worst case scenario model (i.e., a person living at the fence line 24 hours per day, 365 days per year breathing perimeter air and drinking sewer water at ICRP “reference man” recommended rates).

Information and Recommendations from Canadian Nuclear Safety Commission Staff In the Matter of

Zircatec Precision Industries Inc.

emissions to airemissions to sewer

fence line perimeter


When it approved the DRLs for each nuclear generating station, the AECB considered the environmental pathways through which radioactive material could reach the most exposed members of the public after being released from the facility. The most exposed members of the public are called the “critical group.”They are defined as those individuals who are expected to receive the highest dose of radiation because of such considerations as their age, diet, lifestyle and location.

Radioactive Release Data from Canadian Nuclear Generating Stations 1990 to 1999. INFO-0210/REV. 10

Canadian Nuclear Safety Commission, October 2000

environmental pathways

locationage, diet, lifestyle


Radioactive release over a year

Critical group

Regulatory dose limit

Releases of each radionuclide below 1% of the DRL

A limit imposed

Licensed nuclear facility

Reasonable assurance

Emissions to air

Emissions to sewer

Fence line

Perimeter

Environmental pathways

Age, diet, lifestyle

Location

What is…

… that…

… is allowed to…

… so that the total dose aquired by an individual from the …

… selected based on …

… would not exceed ( ) the…

… , via all…

?

Problem StatementProblem Statement


Radioactive release over a year

Critical group

Regulatory dose limit

Releases of each radionuclide below 1% of the DRL

A limit imposed

Licensed nuclear facility

Reasonable assurance

Emissions to air Emissions to sewer

Fence linePerimeter

Environmental pathways

Age, diet, lifestyle Location

What is…

… that…

… is allowed to…

… so that the total dose aquired by an individual from the …

… selected based on …

… would not exceed ( ) the…

… , via all…

?

What is the radioactive release over a year (Bq/year) that a nuclear facility is allowed to emit to environment (air, surface water, sewer) so that the total dose acquired by an individual (total effective dose equivalent – TEDE) from the critical group would not exceed (within reasonable assurance) the regulatory dose limit?

DRL


Ensure that the facility IS operated so that

Taking into account All the individual installations, All the nuclides released to environment, All exposure pathways,

The TOTAL EFFECTIVE DOSE EQUIVALENT – TEDE,POTENTIALLY acquired by an individual from the CRITICAL GROUPbe less or equal to A FRACTION, P, NEGOCIABLE,of the regulatory dose limit.






(…) procedure for application to radioactive discharges and is addressed to the national regulatory bodies and technical and administrative personnel responsible for performing environmental impact analyses.

(…) provides a practical generic methodology for assessing the impact of radionuclide discharges in terms of the resulting individual and collective radiation doses.


Special cases: 3H, 14CSpecific Activity Models…


3H 3H2OAIRWATER

the dose rate (Sv/a) for 3H to the body of a representative member of the critical group;

the steady state concentration of 3H in atmospheric water vapour (Bq/L) at location x1 resulting from airborne releases,

the fraction of the total water intake that is derived from atmospheric water vapour at location x1

steady state concentration of 3H in water at location x2 resulting fromreleases to the aquatic environment (Bq/L)

the fraction of the total water intake of the potentially exposed person that is derived from water at location x2 that has been contaminated with aquatic discharges of tritiated water

the dose rate conversion factor (Sv/a per Bq/L of human body water content).

the concentration of 3H in air at location x1 (Bq/m3)

the absolute humidity of the atmosphere

INTERNATIONAL COMMISSION ON RADIOLOGICAL PROTECTION,Age-dependent Doses to Members of the Public from Intake of Radionuclides, Part 5,

Compilation of Ingestion and Inhalation Dose Coefficients, ICRP Publication No. 72,Pergamon Press, Oxford and New York (1996).


14C 14CO2

the effective dose rate (Sv/a)

the specific activity (Bq 14C per gram of C) to which food products at location x will be chronically exposed

the fraction of total dietary carbon derived from location x by the representative member of the critical group

the effective dose rate factor that relates the annual dose rate (Sv/a) to the concentration of 14C per gram of carbon in people (Bq/g).

the concentration of 14C in air at location x (Bq/m3)

the concentration of airborne carbon, assumed to be 1.8 × 10–1 g/m3,corresponding to an average atmospheric CO2 concentration of 330 ppm

KILLOUGH, G.G., ROHWER, P.S., A new look at the dosimetry of 14C released to the atmosphere as carbon dioxide, Health Phys. 34 (1978) 141–159.


1 Pre-AssessmentBuild the Situation Map

Acquire image maps;Geo-reference the maps;Build source pattern;Build receptor pattern. 2 Assessment

3 Wrapping-up

DRL{g; r, p, s, n}

For each critical group, source, nuclide, receptor, and pathway - compute the DRL.

- g: critical group identifier;

- r: receptor identifier;

- p: pathway identifier;

- s: source identifier;

- n: nuclide

The Conformity criterion*

- L(p,s,n): current emission level (Bq/s);- g: critical group identifier;- r: receptor identifier;- p: pathway identifier;- s: source identifier;- n: nuclide

1,,,;

,,

,

nsprgDRL

nspL

rgC p s n


Illustrative ExamplesIllustrative Examples

Example 1 One Source, One Receptor, One Nuclide

Example 2 Multiple Sources, Multiple Receptors, Multiple Nuclides

The cases are purely fictitious; the assessment is performed in a ‘blind run’ philosophy, using model’s default input values.


No. of Sources: 1No. of Receptors: 1Released Nuclide(s): 3HRelease Pathway: air



Site Map Description: Northern Latitude (deg): 44.3592277Western Longitude (deg): 26.0336333Latitude Span (deg): 0.0185129Longitude Span (deg): 0.0311861


Acquire image maps;Geo-reference the maps;Build source pattern;Build receptor pattern.



Source #1Latitude (deg.): 44.3514298Longitude (deg.): 26.0473757





RECEPTOR #1Latitude (deg): 44.3565349Longitude (deg): 26.0428868





2 Assessment

DRL{g; r, p, s, n}


Source: Source #1Receptor: Receptor #1Source to Receptor Distance (km): 0.67131475Receptor Sector No. (1 to 12): 12Nuclide: H-3Release to AIR

DOSE CRITERIA

Maximum Admissible Dose from Source, to population, (Sv in 1a): 0.00001Maximum Admissible Dose from Source, to workers (Sv in 1a): 0.00005========================D.40. The DERIVED RELEASE LIMIT based on Infant Dose (Bq/s): 923077.477D.41. The DERIVED RELEASE LIMIT based on Adult Dose (Bq/s): 923077.477D.42. The DERIVED RELEASE LIMIT based on Workers Dose (Bq/s): 4615387.38========================

C O N C L U S I O N

D.43. THE RECOMMENDED DERIVED RELEASE LIMIT FOR THE......ANNUAL AVERAGE DISCHARGE RATE TO ATMOSPHERE of H-3, Qi (Bq/s), is: 923077.477......The consequent admissible Total Annual Discharge to Atmosphere..... of H-3 is: 2.91101713e13 Bq, i.e 786.761387 Ci.......DERIVED RELEASE LIMIT FACTOR, Infants, DRLFi (1/Sv): 9.23077477e10......DERIVED RELEASE LIMIT FACTOR, Adults, DRLFa (1/Sv): 9.23077477e10



3 Wrapping-upThe Conformity criterion*

1,,,;

,,

,

nsprgDRL

nspL

rgC p s n

1

10*2.91101713

,,1

,,1,12,;1

,,1

,,,;

,,13

3

3

3

HaL

HaDRL

HaL

npsrgDRL

npsL

p n



AUTHORIZATION OPERATION

110*2.91101713

,,11,1

13

3

HaL

C

Estimated Release Quantity of 3H

3.5 * 1013 [Bq per a]

C[1,1] = 1.2023288

REJECTED

What is it good for…What is it good for…



110*2.91101713

,,11,1

13

3

HaL

C

Estimated Release Quantity of 3H

3.5 * 1013 [Bq per a] 2.3 * 1013 [Bq per a]

C[1,1] = 1.2023288 C[1,1] = 0.7901018

REJECTED

APP

RO

VED



110*2.91101713

,,11,1

13

3

HaL

C

Current Release Status of 3H2.51546 * 1013 [Bq]

0.5 * 1013 [Bq]

C[1,1] = 1.0358784

3.01546 * 1013 REJECTED



110*2.91101713

,,11,1

13

3

HaL

C

Current Release Status of 3H2.51546 * 1013 [Bq]

0.5 * 1013 [Bq]

C[1,1] = 1.0357842.81546 * 1013

REJECTED

0.3 * 1013 [Bq]

C[1,1] = 0.9671739

APP

RO

VED


No. of Sources: 2No. of Receptors: 3Released Nuclide(s):


Source Nuclide Pathway

Source #1 I-125I-131Cs-134

AirAirAir

Source #2 I-131Sr-90

AirAir

























2 Assessment

DRL{g; r, s, p, n}


DRL(g;12,1,a,n)



2 Assessment

DRL{g; r, s, p, n}


DRL(g;12,1,a,n)DRL(g;10,1,a,n)



2 Assessment

DRL{g; r, s, p, n}


DRL(g;12,1,a,n)DRL(g;10,1,a,n)DRL(g;6,1,a,n)



2 Assessment

DRL{g; r, s, p, n}



DRL(g;12,2,a,n)



2 Assessment

DRL{g; r, s, p, n}






2 Assessment

DRL{g; r, s, p, n}



DRL(g;12,2,a,n)DRL(g;12,1,a,n)DRL(g;10,1,a,n)DRL(g;6,1,a,n)



2 Assessment

DRL{g; r, s, p, n}






2 Assessment

DRL{g; r, s, p, n}


SOURCE #1 SOURCE #2

Receptor #1

Nuclide Nuclide

134Cs DRLinfantsDRLadultsDRLworkersTotal adm.

0.66998346 Bq/s0.42476349 Bq/s2.12381746 Bq/s21128598.4 Bq 0.5710432e-3 Ci

131I DRLinfantsDRLadultsDRLworkersTotal adm.

0.53372928 Bq/s3.64434313 Bq/s18.2217157 Bq/s16831686.7 Bq 0.45491045e-3 Ci


0.49817987 Bq/s1.16820263 Bq/s5.84101316 Bq/s15710600.2 Bq0.42461082e-3 Ci

90Sr DRLinfantsDRLadultsDRLworkersTotal adm.

0.11983303 Bq/s0.20212424 Bq/s1.01062122 Bq/s3779054.44 Bq 0.10213661e-3 Ci


0.53369439 Bq/s3.64410492 Bq/s18.2205246 Bq/s16830586.3 Bq0.45488071e-3 Ci



2 Assessment

DRL{g; r, s, p, n}


SOURCE #1 SOURCE #2

Receptor #2

Nuclide Nuclide


0.66998346 Bq/s0.42476349 Bq/s2.12381746 Bq/s21128598.4 Bq 0.5710432e-3 Ci


0.53372971 Bq/s3.64434606 Bq/s18.2217303 Bq/s16831700.0 Bq 0.45491081e-3 Ci


0.4981797 Bq/s1.16820225 Bq/s5.84101125 Bq/s15710595.2 Bq 0.42461068e-3 Ci


0.11983303 Bq/s0.20212424 Bq/s1.01062122 Bq/s3779054.44 Bq 0.10213661e-3 Ci


0.5336931 Bq/s3.64409612 Bq/s18.2204806 Bq/s16830545.7 Bq 0.45487961e-3 Ci



2 Assessment

DRL{g; r, s, p, n}


SOURCE #1 SOURCE #2

Receptor #3

Nuclide Nuclide


0.66998448 Bq/s0.42476414 Bq/s2.12382069 Bq/s21128630.5 Bq 0.57104407e-3 Ci


0.53374312 Bq/s3.64443761 Bq/s18.222188 Bq/s16832122.9 Bq 0.45492224e-3 Ci


0.49818939 Bq/s1.16822496 Bq/s5.84112481 Bq/s15710900.6 Bq 0.42461893e-3 Ci


0.11983303 Bq/s0.20212424 Bq/s1.01062122 Bq/s3779054.44 Bq 0.10213661e-3 Ci


0.5337708 Bq/s3.64462665 Bq/s18.2231332 Bq/s16832996.0 Bq 0.45494584e-3 Ci




Receptor #1




Receptor #2




Receptor #3



OPERATION

Receptor #1

Receptor #2

Receptor #3

Current Release Status of The Compund [Receptor #1]



All but 131I, Source #1



131I, Source #1 [Bq]

131I, Source #1

131I, Source #1

0.75

L(1,a,131I)=4000000Max adm. 16830586.3 0.23766

131I 2B Relesed: 210000 Bq

0.65

L(1,a,131I)=3000000Max adm. 16830545.7

0.17824

0.70

L(1,a,131I)=4000000Max adm. 16832996.0

0.23763


OPERATION

Receptor #1

Receptor #2

Receptor #3








131I, Source #1

131I, Source #1

0.75

L(1,a,131I)=4210000Max adm. 16830586.3 0.25014


0.65

L(1,a,131I)=3000000Max adm. 16830545.7

0.17824

0.70

L(1,a,131I)=4000000Max adm. 16832996.0

0.23763

Res 0.25010

Wind from Source #1 towards Receptor #1 (sector 12)

>1


OPERATION

Receptor #1

Receptor #2

Receptor #3








131I, Source #1

131I, Source #1

0.75

L(1,a,131I)=4210000Max adm. 16830586.3 0.25014


0.65

L(1,a,131I)=3210000Max adm. 16830545.7

0.19072

0.70

L(1,a,131I)=4000000Max adm. 16832996.0

0.23763


>1


<1


OPERATION

Receptor #1

Receptor #2

Receptor #3








131I, Source #1

131I, Source #1

0.75

L(1,a,131I)=4210000Max adm. 16830586.3 0.25014


0.65

L(1,a,131I)=3210000Max adm. 16830545.7

0.19072

0.70

L(1,a,131I)=4210000Max adm. 16832996.0

0.25010


>1


<1

<1


REJECTED

APPROVED

APPROVED


He who has the bread and the knife tells the name of the game…

(Romanian popular wisdom)DRLs ARE NEGOCIABLE!The Dose Constraint (P factor)…

The Relevant Pathways…

Choosing the critical group…

Choosing the receptor configuration (number, locations, etc.)…

Other model parameters…

emission release heights,

diet,

irrigation regime, etc.

The Final Word?!..The Final Word?!..

Thank you.

Documents

Assessing Prolonged Exposures. The DRL Approach