PROTECTFP6-036425 PROTECT recommendations – application in practice.

FP6-036425FP6-036425PROTECT PROTECT

PROTECT recommendations –

application in practice


Outline

• Overview of approaches to assessment/available assessment tools

• Uncertainty/variability in model predictions

• Put the PROTECT benchmark values into context of results of existing environmental assessments

• Optimisation

• Revisit concepts

• Introduce breakouts

IAEA EMRAS Biota IAEA EMRAS Biota Working GroupWorking Group

Internal dose ratesInternal dose rates

• Internal dose estimates generally all within 20 % of mean (of predictions)– exception being for U-238: two approaches

including U-234 as daughter (resulting in 2x higher DCC)

External dose ratesExternal dose rates• Considerably more variable between models –

especially for β- emitters

e.g. Duck on soil surface e.g. Duck on soil surface predictions for Sr-90predictions for Sr-90

1.E-11

1.E-10

1.E-09

1.E-08

1.E-07

1.E-06

1.E-05

1.E-04

1.E-03

AECL EA EDEN ERICA LIETDOS RESRAD SCK SUJB

DC

C

External dose ratesExternal dose rates• More variable between models – especially for β-

emitters– Especially H-3 & C-14 (e.g. external DCC for duck on

soil for H-3 ranged 0 to 5E-11)

• Media assumptions (density and distribution of contamination) can be seen to result in some variation

• Differences in approaches that do not matter:– use of specific geometries v’s nearest default– number of emissions assumed

Predicted activity concentrationsPredicted activity concentrations• Considerable variation between predictions (3-

orders of magnitude being common)

Pu-239

Predicted activity concentrationsPredicted activity concentrations• Some variation can be understood, e.g.:

– Missing value guidance approach often give comparatively high estimates (often for little studied organisms)

– Site specific (and national) data– Some approaches include reindeer data in derivation

of CRs leading to high predictions for mammals (especially Po-210)

• Tc-99 predictions had least variation– Very few data and all using similar approach


PROTECT WP2 comparison of screening Tier predictions

• Comparison of initial screening tier against the same screening level (for example USDOE values adopted)– Limiting RQs compared


Terrestrial

RESRAD-BIOTA & ERICA-Tool

+ EA R&D128Variation appears to be predominantly due to transfer components


Example - England & Wales ‘Habitats’ assessments

• Assessed 715 radioactive discharge authorisations

• Screening level of 5 µG/h used

• 600 authorisations did not require assessment more detailed than initial conservative level (i.e. estimate < 5 µG/h)

• Only 9 sites would exceed PROTECT proposed 10 µG/h generic screening level

• One site exceeds 450 µG/h

• Most exposed organism at this site = marine mammal (very conservative assessment)


Example assessment results• Used data from SENES 2007 (report for WNA) [+

some additional ERICA case study site data + EcoMetric Chalk River Lab. report]

• Considers results of published assessments for range of sites

• Used presented media activity concentration data to run through ERICA Tool (Tier 2 – default parameters) to determine weighted whole-body absorbed dose rates

• Most media activity concentrations presented as ‘upper bound’ or maximums

• Note not all assessments considered by SENES (& ERICA) were complete assessments


Terrestrial assessments

Marine assessmentsInput data for SSD fit EDR10 EDR25 EDR50

Number of data 19 17 14

r2 0.958 0.965 0.953

HDR5 8 30 86HDR10 27 85 217HDR20 114 302 665HDR50 1741 3385 5641


Freshwater assessments


AECL Chalk River Laboratories

0

2

4

6

8

10

12

14

16

18

20

Fish Frog Snail Aquaticplant

Riparianplant

Watershrew

Heron Turtle Muskrat Mallard Benthos

Nu

mb

er

of

ma

x e

sti

ma

tes

>450 uGy/h

>10 uGy/h

<10 uGy/y


AECL Chalk River Laboratories

0

5

10

15

20

25

30

35

40

45

Invertebrates Plants Shrew American Robin Wodchuck

Nu

mb

er

>450 uGy/h>10 uGy/h<10 uGy/y


Summary• Generic screening value (10 µGy/h) is likely

to identify sites of negligible risk (EA Habitats assessments)

• The ‘taxonomic’ screening level for ‘non-vertebrates’ (450 µGy/h) attempts to account for radiosensitivity – in example assessments appears to be fit for purpose– Identifying sites requiring more refined

assessment

PROTECTFP6-036425 PROTECT recommendations – application in practice.

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Transcript of PROTECTFP6-036425 PROTECT recommendations – application in practice.