Release of natural radionuclides from NORM-residues caused by sewage J. Dilling 1, K. Flesch 2, R. Gellermann 3, J. Gerler 1, H. Hummrich 2, V. Neumann 4, R. Knappik 5, H. Schulz 2 1 Federal Office for Radiation Protection, Berlin 2 IAF - Radioökologie GmbH, Dresden 3 FUGRO-HGN GmbH, Magdeburg 4 BGD, Dresden 5 VKTA, Rossendorf 2nd Workshop of the European ALARA Network for NORM, Dresden 2009

Legal Framework Introduction of surveillance limits depending on the recycling or disposal option If exceeding SLs site specific dose assessments (realistic scenarios, parameters, models) formal release of surveillance necessary Precondition: D < 1mSv/a (members of the public) Radiation Protection Ordinance  Positive List joint disposal depending on specific activity and landfill parameters

— inhalation of Radon and its decay products — inhalation of contaminated dust — direct ingestion of contaminated soil — exposure to external gamma radiation — ingestion of locally produced food (incl. drinking water) Dose assessment Pathways of concern  grown on contaminated sites  irrigation with contaminated water

Dose assessment Pathway: Ingestion of locally produced food focussing on water disposed or recycled NORM seepage water ground water well surface water source term: which radionuclide concentrations will be released?

Approach Crosslink conventional hazards Standard methods for assessing waste and contaminated soil regarding potential groundwater contaminations Present study  Feasibility study regarding methodical approaches — soil saturation extract — pH-Stat — elution with water (1:10, 1:2 respectively) — column experiments

Approach Soil saturation extract (technical realisation) original sample + deion. water to moisten completely, keeping 24 h at 5°C adding water until flow limit is reached, keeping another 24 h at 5°C centrifugation and filtration with membrane filters (pore size 0,45 µm)

original sample + deion. water to moisten completely, keeping 24 h at 5°C adding water until flow limit is reached, keeping another 24 h at 5°C centrifugation and filtration with membrane filters (pore size 0,45 µm) Methodical advantages and disadvantages — close to reality material/water ratio (+) — no fixed water / solid ratio (-) — small sample volume (5-30ml /100g) (-) — not convenient for very fine and very coarse textured material (-) Approach Soil saturation extract

Approach pH-Stat (technical realisation) field moist sample + deion. Water (1:10), 24 h stirring, adding HNO 3 by means of an automatic titrator until pH 4 filtration with membrane filters (pore size 0,45 µm)

Approach pH-Stat field moist sample + deion. Water (1:10), 24 h stirring, adding HNO 3, by means of an automatic titrator until pH 4 filtration with membrane filters (pore size 0,45 µm) Methodical advantages and disadvantages — determination of the leachable contaminants according to a worst-case scenario (+) — information of buffering capacity (+) — no pH-Stat experiment at low pH value (<4) (-)

Approach Elution with water 1:10 and 1:2 (technical realisation) field moist sample + deion. Water (1:10, 1:2 respectively) 24 h overhead-rotating shaker at room temperature filtration with membrane filters (pore size 0,45 µm)

Approach Elution with water 1:10 and 1:2 field moist sample + deion. Water (1:10, 1:2 respectively) 24 h overhead-rotating shaker at room temperature filtration with membrane filters (pore size 0,45 µm) Methodical advantages and disadvantages — leachate volume large enough for the following analysis (+) — abrasion of particles during the extraction procedure (-) — 1:10 material/water ratio: excess water 1:2 material/water ratio closer to reality (see soil sat. Extract)

Approach Column experiment – experimental setup insert sample in column, wetting from downside up within 24 h keeping 24 h at 10°C exchange of one pore volume within 24 h intermittently driven 6-20x

Approach „steady-state“ Column experiment – end of experiment „quasi steady state“ situation  no alteration in physico-chemical properties like pH, redox-potential

Approach „steady-state“ Column experiment – end of experiment „quasi steady state“ situation  no alteration in physico-chemical properties like pH, redox-potential

Approach Determining the source term column experiment C t soil saturation extract elution with water 1:10 elution with water 1:2 t different concentration levels expected !!

Approach 28 different NORM residues investigated — slags from primary metallurgic processes in the raw iron and non- ferrous metallurgy — sludges and dust from the smoke gas filtering with the primary metallurgic processes in the raw iron and non-ferrous metallurgy — sludges and sediments from the recovery of oil and natural gas (Scales) — red mud from the extraction of bauxite — tailings from the extraction of uranium — residues of water treatment facilities

Approach — U-238 series: U-238, Th-230, Ra-226, Pb-210, (Po-210) — U-235 series: Ac-227 — Th-232 series: Ra-228, Th-228, (Th-232) — K-40 Residue — U-238, Ra-226, Pb-210, Ra-228 (Th-228, Ac-227, Po-210) — Major ions: Cl -, HCO 3-, SO 4 2-, Na +, K +, Ca 2+, Mg 2+ — pH, electrical conductivity Leachate Analysing methods — Gamma spectrometry — Alpha spectrometry — Liquid Scintillation Counting (LSC) — ICP-MS Analysed parameters

Results Data mining activity-concentration scaled on pore volume a i PV of undisturbed soil: a i leachate : activity-concentration in leachate [Bq/l] WF: Water/material ratio [l/kg]  d : oven-dry density [g/cm³] n: porosity leachable fraction R i : A i : specific activity [Bq/kg] Different water / solid ratios  results not comparble  normalisation required

Results U-238 activity concentration scaled on pore volume Due to the acidification during the pH-Stat experiment trends to result in highest concentration

Results U-238 leachable fraction Tailings: close to 100% release feasible

Results Ra-226 activity concentration scaled on pore volume Due to the acidification during the pH-Stat experiment trends to result in highest concentration

Results Ra-226 leachable fraction Low leachable fraction for demercurised residues and scales

Results Pb-210 activity concentration scaled on pore volume Highest concentration due to the acidification during the pH- Stat experiment are evident

Results Pb-210 leachable fraction Elevated leachable fraction for sinter dust and water work residues

Results Data mining column experiments relative leached load F i rel m : mass of material in column [kg] Ai: specific activity [Bq/kg] a i leachate,n : activity conc. in n-th leachate [Bq/l] V leachate,n : volume n-th leachate [l] total leached load A i n,abs

Results Theisen sludge – intermittently driven column experiment

Results Theisen sludge – comparison between different leaching methods

Results Tailings – intermittently driven column experiment

Results Tailings – comparison between different leaching methods

Conclusions — This present study is the first complex investigation about the release of radionuclides by sewage from NORM. — The soil saturation extract offers only a marginal sample volume, meaning the determination of radionuclides is in many cases impossible. — The elution with water is easy to handle and gives qualitative informations about the radionuclides released. — Caused by the lowered pH of 4 the results of pH-Stat experiments show, as expected, higher activity concentrations compared to other methods.

Conclusions — The realisation of intermittently driven column experiments is more sophisticated compared to batch experiments, but the results offer informations about time depending leaching of radionuclides. — No alteration in the physico-chemical properties (e.g. pH and redox-potential) assumed the electric conductivity is a suitable parameter to determine „quasi steady-state“ conditions. — The transferability of the well-established methods (elution with water, the pH-Stat, intermittently driven column experiments) from waste legislation on radiological purposes could be shown.

Thank you for your attention

Legal Framework — sludges and sediments from oil and natural gas extraction — unconditioned phosphor gypsum, dust, sludges and slags occurring during processing of raw phosphate — waste rock, sludges, sands, slags and dusts from the extraction and preparation of bauxite, columbite, copper shale, tin… — dust and sludge from smoke gas filtering within primary metallurgic processes in the raw iron and non-ferrous metallurgy Exception: C < 0,2 Bq/g Introduced in technological processes specified in the positive list as raw material List of residues requiring surveillance (Radiation Protection Ordinance – RPO): “Positive List”

Legal Framework — Based on Directive 96/29 EURATOM (European Basic Safety Standards) — Systematic research for identifying relevant processes and materials — Radiological criterion: 1 mSv/a to members of the public (added to the natural background level) — Results: fate of particular industrial residues of concern U-238 and Th-232 series relevant List of residues needing surveillance – Radiation Protection Ordinance (RPO 2001)

NORM residues Slags from primary metallurgic processes in the raw iron and non- ferrous metallurgy P1.1 Ni-Slags P1.2 Cu-Slags P1.3 Sandy residues from tin ore prosessing P1.8 Casting cinder P1.10 Phosphate slags 5 cm P1.10

NORM residues Sludges and dust from the smoke gas filtering with the primary metallurgic processes in the raw iron and non-ferrous metallurgy P2.5 Theissen sludge P2.9 Furnace gas sludges P2.13 Sinter dust P2.14 Furnace gas sludges P2.15 Sinter dust

NORM residues Sludges and sediments from the recovery of oil and natural gas (Scales) 5 cm 2 cm P3.2 P3.3 P3.4 P3.5 P3.13P3.6 P3.2 to P3.5 demercurised residues P3.6 & P3.13 dry Scales  Not considered: oily sludges

NORM residues Red Mud from the extraction of bauxite P4.1 Red mud Lauta P4.2 Red mud AOS Stade

NORM residues Tailings from the extraction of Uranium P5.1, P5.3 & P5.4 silt-dominated Tailings P5.2 sand-dominated Tailings 5 cm P5.1 P5.3 P5.4 P5.2

NORM residues Residues of water treatment facilities P6.1, P6.3, P6.6 & P6.7 different filter gravel P6.9 Filtrolite P6.11 powdered immobilisate (mine water clean up from former uranium mining)

Results Activityconcentration normalised to porevolume

Results Activityconcentration normalised to porevolume

Results Activityconcentration normalised to porevolume