1 Introduction
-
Mineral scales, deposits and thin films (radon progeny) accumulate in plant equipment and particularly adherent to tubular (drill pipes, casings and tubulars); and
-
Petroleum hydrocarbon (PHC)-sludge and scrapings from cleaning and pigging activities, which contain radioactive mineral solids.
1.1 Mineral Scale
1.2 NORM Sludge
1.3 Lead Films
1.4 Black Dust
1.5 Hazards of NORM
1.6 Objective of this Paper
2 Theory
2.1 Existence and Origin of Soluble Uranyl Minerals in Carbonate Formation Rocks
Mineral Name | Mineralogical Formula (IMA) | Crystal System |
---|---|---|
Carnotite | K2(UO2)2(VO4)2 · 2–3H2O | Monoclinic |
Strelkinite | Na2(UO2)2(VO4)2 · 6H2O | Orthorhombic |
Tyuyamunite | Ca(UO2)2(VO4)2 · 5–8H2O | Orthorhombic |
Metatyuyamunite | Ca(UO2)2(VO4)2 · 3–5H2O | Orthorhombic |
Vanuralite | Al(UO2)2(V2O8)(OH) · 11H2O | Monoclinic |
Metavanuralite | Al(UO2)2(VO4)2(OH) · 8H2O | Triclinic |
Margaritasite | (Cs,K,H3O)2(UO2)2(VO4)2 · H2O | Monoclinic |
Sengierite | Cu2(UO2)2(VO4)2(OH) 2 · 6H2O | Monoclinic |
Vanuranylite | (H3O)2(UO2)2(VO4)2 · 4H2O | Monoclinic |
Curienite | Pb(UO2)2(VO4)2 · 5H2O | Orthorhombic |
Francevillite | (Ba,Pb)(UO2)2(VO4)2 · 5H2O | Orthorhombic |
Fritzscheite | Mn(UO2)2(PO4,VO4)2 · 10H2O | Tetragonal |
2.2 Description of the Study Area and Origin of the NORM Samples
3 Experimental and Interpretation of Analysis Results
3.1 Gamma-ray Spectroscopy
3.1.1 Gamma Spectroscopy Applying a NaI(Tl) Scintillation Radiation Detector
Sr. No | Sample Name | 226Ra [Bq/g] | 214Pb [Bq/g] | 214Bi [Bq/g] |
---|---|---|---|---|
1 | SCALE-A-67 | 23.5 ± 0.3 | 14.1 ± 0.3 | 10.4 ± 0.4 |
2 | SCALE-A-68 | 8.4 ± 0.2 | 5.1 ± 0.1 | 2.9 ± 0.1 |
3 | SCALE-A-73 | 2.9 ± 0.1 | 2.04 ± 0.02 | 1.42 ± 0.03 |
4 | SCALE-A-75 | 1.5 ± 0.2 | 0.66 ± 0.02 | 0.49 ± 0.03 |
5 | SCALE-B-42 | 50 ± 1 | 39 ± 2 | 35 ± 2 |
6 | SCALE-B-44 | 145 ± 4 | 110 ± 3 | 105 ± 3 |
7 | SCALE-B-48 | 53 ± 2 | 42 ± 1 | 39 ± 1 |
8 | SCALE-B-61 | 51 ± 2 | 36 ± 1 | 39 ± 1 |
9 | SCALE-B-63 | 33 ± 1 | 25 ± 1 | 24 ± 1 |
10 | SCALE-B-64 | 36 ± 1 | 33 ± 1 | 32 ± 1 |
Sr. No | Sample Name | 235U [Bq/g] | 234Th [Bq/g] |
---|---|---|---|
1 | SCALE-A-69 | 0.25 ± 0.02 | 5.2 ± 0.2 |
2 | SCALE-A-70 | 0.46 ± 0.04 | 9.5 ± 0.5 |
3 | SCALE-A-72 | 0.36 ± 0.04 | 6.2 ± 0.4 |
4 | SCALE-A-80 | 0.26 ± 0.02 | 4.4 ± 0.2 |
5 | SCALE-A-82 | 0.35 ± 0.07 | 9 ± 2 |
6 | SCALE-B-34 | 0.41 ± 0.04 | 11.5 ± 0.4 |
7 | SCALE-B-35 | 0.36 ± 0.01 | 8.6 ± 0.4 |
3.1.2 Gamma Spectroscopy Applying a High Purity Germanium (HPGe) Radiation Detector
234Th [Bq/g] | 234Th [Bq/g] | 234 mPa [Bq/g] | 234U [Bq/g] | 235U [Bq/g] | 235U [Bq/g] | |
---|---|---|---|---|---|---|
SCALE-A-72 | 8.9 ± 0.7 | 6.2 ± 0.4 | 8.2 ± 0.6 | 8.6 ± 0.9 | 0.42 ± 0.03 | 0.36 ± 0.04 |
SCALE-A-67 | SCALE-A-68 | |
---|---|---|
226Ra [Bq/g] | 14.9 ± 0.6 | 3.95 ± 0.16 |
226Ra [Bq/g] | 23.5 ± 0.3 | 8.4 ± 0.2 |
214Pb [Bq/g] | 14.1 ± 0.3 | 5.1 ± 0.1 |
214Bi [Bq/g] | 10.4 ± 0.4 | 2.9 ± 0.1 |
234Th [Bq/g] | 7.28 ± 0.39 | 5.35 ± 0.29 |
234 mPa [Bq/g] | 7.6 ± 0.8 | 5.2 ± 0.5 |
235U [Bq/g] | 0.34 ± 0.03 | 0.24 ± 0.18 |
210Pb [Bq/g] | 1.83 ± 0.14 | <12 |
228Ra [Bq/g] | 0.026 ± 0.009 | 0.011 ± 0.004 |
40K [Bq/g] | <0.057 | <0.025 |
3.2 Chemical Analysis and Mineralogical Interpretation
3.2.1 Visual Pre-examination of Selected Scale Samples
3.2.2 Inductively Coupled Plasma-Mass Spectrometric Analysis (ICP-MS)
Sample Name | Mass [mg] | Wet digestion procedure | Total Dilution Factor |
---|---|---|---|
SCALE-A-67 | 0.2745 | 5 ml conc. HNO3 (69% w/w) + 2 ml conc. HCl (37% w/w) + 0.5 ml conc. HF (49% w/w) in ultrasonic bath for 2 days at 60 °C | 5464 |
SCALE-A-68 | 0.2639 | 5684 | |
SCALE-A-72 | 0.2781 | 5394 |
SCALE-A-67 [ppb] | SCALE-A-68 [ppb] | SCALE-A-72 [ppb] | SCALE-A-67 [ppb] | SCALE-A-68 [ppb] | SCALE-A-72 [ppb] | ||
---|---|---|---|---|---|---|---|
Fe | 2.1E + 08 | 2.9E + 08 | 3.2E + 08 | Li | 4.3E + 04 | 2.5E + 04 | 1.7E + 04 |
Sr | 8.6E + 07 | 2.1E + 07 | 4.0E + 04 | Sb | 8.4E + 03 | 1.0E + 04 | 2.8E + 03 |
Ca | 5.3E + 07 | 1.7E + 07 | 7.0E + 06 | Ge | 6.7E + 03 | 9.5E + 03 | 9.5E + 03 |
Ba | 7.2E + 06 | 7.0E + 06 | 7.3E + 04 | B | 1.0E + 04 | 6.4E + 03 | 4.8E + 03 |
Mn | 2.2E + 06 | 3.0E + 06 | 4.0E + 06 | Rb | 8.4E + 02 | 1.1E + 03 | 1.0E + 03 |
Cr | 5.6E + 06 | 1.5E + 06 | 5.1E + 05 | Ce | 9.0E + 02 | 8.1E + 02 | 3.1E + 02 |
Mg | 2.3E + 06 | 1.1E + 06 | 2.3E + 06 | La | 6.2E + 02 | 6.4E + 02 | 1.8E + 02 |
Zn | 1.5E + 06 | 6.8E + 05 | 1.7E + 05 | Eu | 5.8E + 02 | 5.5E + 02 | <21.00 |
Cu | 5.9E + 05 | 5.4E + 05 | 7.2E + 04 | Y | 1.0E + 03 | 4.7E + 02 | 1.6E + 02 |
Al | 5.7E + 05 | 5.3E + 05 | 4.1E + 05 | Th | 1.7E + 02 | 1.5E + 02 | 1.1E + 02 |
U | 6.8E + 05 | 4.9E + 05 | 6.8E + 05 | Gd | 1.5E + 02 | 1.4E + 02 | <68.00 |
Ga | 3.1E + 05 | 3.1E + 05 | 5.7E + 03 | Bi | 2.4E + 02 | 1.3E + 02 | 9.9E + 01 |
Ni | 2.6E + 05 | 3.1E + 05 | 1.2E + 05 | Sm | 1.0E + 02 | 1.2E + 02 | <81.00 |
Na | 6.5E + 05 | 2.8E + 05 | 3.9E + 05 | Pr | 9.5E + 01 | 1.0E + 02 | 3.0E + 01 |
K | 2.7E + 05 | 2.3E + 05 | 2.4E + 05 | Ag | 1.6E + 02 | 8.5E + 01 | 4.3E + 01 |
V | 2.6E + 05 | 2.2E + 05 | 2.2E + 05 | Cs | 2.9E + 01 | 5.1E + 01 | 8.8E + 01 |
Se | 2.2E + 05 | 1.9E + 05 | 1.6E + 05 | Ho | 1.1E + 01 | 1.1E + 01 | <10.00 |
Co | 1.4E + 05 | 1.4E + 05 | 2.4E + 05 | Er | 3.9E + 01 | <34.00 | <32.00 |
As | 6.9E + 04 | 1.0E + 05 | 2.1E + 04 | Sc | <2000 | <2000 | <2000 |
Mo | 5.6E + 04 | 9.5E + 04 | 1.8E + 04 | Cd | <170.0 | <180.0 | 4.7E + 02 |
Pb | 5.2E + 04 | 7.1E + 04 | 1.9E + 05 | Tb | 1.7E + 01 | <10.00 | <10.00 |
SCALE-A-67 | SCALE-A-68 | SCALE-A-72 | |
---|---|---|---|
Th [ppm] | 0.19 | 0.13 | 0.12 |
U [ppm] | 740 | 470 | 700 |
Vanadium—Uranium | Copper—Uranium | Lead—Uranium | |
---|---|---|---|
SCALE-A-67 | 1 : 2.62 up to 2.69 | 1 : 1.15 up to 1.19 | 1 : 13.00 up to 13.45 |
SCALE-A-68 | 1 : 2.14 up to 2.23 | 1 : 0.87 up to 0.91 | 1 : 6.62 up to 6.90 |
SCALE-A-72 | 1 : 3.10 up to 3.36 | 1 : 9.44 up to 10.29 | 1 : 3.58 up to 3.89 |
Average | 1 : 2.69 | 1 : 3.97 | 1 : 7.91 |
-
Carnotite K2(UO2)2(VO4)2 · 3H2O has a vanadium-uranium ratio of 1:4.67,
-
Sengierite Cu2(UO2)2(VO4)2(OH)2 · 6H2O has a copper-uranium ratio of 1:3.75,
-
Curienite Pb(UO2)2(VO4)2 · 5H2O has a lead-uranium ratio of 1:2.30.
3.2.3 Uranium Isotopic Ratio Measurements
234U/Tot [%] | 235U/Tot [%] | 238U/Tot [%] | |
---|---|---|---|
SCALE-A-67 | 0.0055 ± 0.0003 | 0.711 ± 0.010 | 99.28 ± 0.02 |
SCALE-A-68 | 0.0058 ± 0.0005 | 0.715 ± 0.010 | 99.28 ± 0.03 |
SCALE-A-72 | 0.0059 ± 0.0003 | 0.714 ± 0.010 | 99.28 ± 0.02 |
IRMM-3184 | 0.0052752 | 0.72096 | 99.27376 |