long term behaviour evaluation of cement conditioning matrices used for management of radioactive...

Long term behaviour evaluation of Long term behaviour evaluation of cement conditioning matrices used for cement conditioning matrices used for management of radioactive wastes at management of radioactive wastes at

IFIN-HHIFIN-HH

L. Ionascu, M. Nicu, F. Dragolici, C. N. Turcanu, L. Ionascu, M. Nicu, F. Dragolici, C. N. Turcanu, Gh. RotarescuGh. Rotarescu

Long term behaviour evaluation of cement conditioning matrices used for management of radioactive wastes Long term behaviour evaluation of cement conditioning matrices used for management of radioactive wastes at IFIN-HHat IFIN-HH

Portland cement matrix Portland cement matrix good mechanical properties : good mechanical properties :

handling, storage, transport and long handling, storage, transport and long term stability term stability

monolith with acceptable mechanical, monolith with acceptable mechanical, chemical and physical properties chemical and physical properties

release of radioactivity from the waste release of radioactivity from the waste form in the environment is minimized.form in the environment is minimized.

Long term behaviour evaluation of cement conditioning matrices used for management of Long term behaviour evaluation of cement conditioning matrices used for management of radioactive wastes at IFIN-HHradioactive wastes at IFIN-HH

XRD application for the phase identification of XRD application for the phase identification of matrix that simulates the conditioned matrix that simulates the conditioned radioactive waste and the correlation with radioactive waste and the correlation with mechanical performancemechanical performance

selected matrices for the study are normal selected matrices for the study are normal cement with iron precipitates.cement with iron precipitates.

information about the chemical reactions information about the chemical reactions between the radioactive precipitates and the between the radioactive precipitates and the hydrates, hydrolysis products of the cement. hydrates, hydrolysis products of the cement.


the chemical nature and proportion the chemical nature and proportion of the precipitation products affect :of the precipitation products affect :- - the hydrolysis of the initial cement components the hydrolysis of the initial cement components

- the reactions of metastable hydration constituents - the reactions of metastable hydration constituents

- mechanical strength and the chemical resistance of the - mechanical strength and the chemical resistance of the

hardened cement systemhardened cement system


Solidification of radioactive wastes with hydraulic cement Solidification of radioactive wastes with hydraulic cement either with or without admixtures either with or without admixtures

the wastes produced by nuclear activities are very diverse the wastes produced by nuclear activities are very diverse and under certain circumstances affect the rate of and under certain circumstances affect the rate of hydration on cement and/or reduce the quality of product hydration on cement and/or reduce the quality of product

IFIN – HH - multiple precipitation based on iron hydroxide IFIN – HH - multiple precipitation based on iron hydroxide and calcium phosphate formation and calcium phosphate formation

data basis necessary for the approach the medium and long data basis necessary for the approach the medium and long term assessment of the safety and performance for final term assessment of the safety and performance for final packages disposed in Radioactive Waste National packages disposed in Radioactive Waste National Repository Baita-Bihor Repository Baita-Bihor


Medium term programme (1997-2010) Medium term programme (1997-2010) was implemented : was implemented :

- study of iron precipitates obtained during - study of iron precipitates obtained during LLAW treatment;LLAW treatment;

- cementation of sludge chemical - cementation of sludge chemical components;components;

- durability of cemented waste in repository - durability of cemented waste in repository and under simulated conditions. and under simulated conditions.


MethodMethod : :

- precipitation of the insoluble compounds - precipitation of the insoluble compounds - LLAW having iron hydroxides and iron LLAW having iron hydroxides and iron phosphatesphosphates

- microstructure analysis on some samples microstructure analysis on some samples obtained through methods that simulate obtained through methods that simulate conditioning of the iron hydroxide and iron conditioning of the iron hydroxide and iron phosphate precipitate.phosphate precipitate.


There were prepared two types of iron There were prepared two types of iron precipitates:precipitates:

the addition of the neutralization agents the addition of the neutralization agents NaOH concentrated to the diluted solution NaOH concentrated to the diluted solution of FeClof FeCl33;;

the Nathe Na33POPO44 addition to the diluted solution addition to the diluted solution of FeClof FeCl33..


The precipitates obtained were The precipitates obtained were conditioned through cementation as conditioned through cementation as it follows:it follows:

cement + iron hydroxide (5g cement + 2.5g wet cement + iron hydroxide (5g cement + 2.5g wet precipitate);precipitate);

cement + iron phosphate (5g cement + 2.5g wet cement + iron phosphate (5g cement + 2.5g wet precipitate).precipitate).


The X-ray investigation was performed with a Dron 2 The X-ray investigation was performed with a Dron 2 diffractometer , using Ni-filtered Cu-Kdiffractometer , using Ni-filtered Cu-K radiation (λ=1.5418 radiation (λ=1.5418 Ǻ), for diffraction angles 2 theta ranged between 5 and 65˚. Ǻ), for diffraction angles 2 theta ranged between 5 and 65˚.

Calculating interplanar distance “d” parameters for all Calculating interplanar distance “d” parameters for all diffraction maxima which appears in the polycrystalline diffraction maxima which appears in the polycrystalline mixture spectrum and comparing with “d” values from mixture spectrum and comparing with “d” values from ASTM cards can be obtained a qualitative analysis for ASTM cards can be obtained a qualitative analysis for crystalline phases. crystalline phases.

For each phase there is a certain minimal proportion of it in For each phase there is a certain minimal proportion of it in a mixture in order to be identified. This minimal proportion a mixture in order to be identified. This minimal proportion depends on the particular phase nature and also on the depends on the particular phase nature and also on the other present phases nature. In the same time with the other present phases nature. In the same time with the growth of the phase content in mixture, the intensity of growth of the phase content in mixture, the intensity of specific lines increases.specific lines increases.


The basic information on the waste matrix is The basic information on the waste matrix is obtained by mechanical strength tests.obtained by mechanical strength tests.

The selected matrices for characterization are The selected matrices for characterization are normal concrete composition as reference normal concrete composition as reference samples and the conditioned matrices prepared samples and the conditioned matrices prepared with non-active precipitate compounds (iron with non-active precipitate compounds (iron hydroxides and iron phosphate) simulating the hydroxides and iron phosphate) simulating the real radioactive sludge.real radioactive sludge.

Samples were positioned in five points (from 1 to Samples were positioned in five points (from 1 to 5) of Radioactive Waste National Repository 5) of Radioactive Waste National Repository Baita-Bihor and kept 1, 3, 5, and 7 years before Baita-Bihor and kept 1, 3, 5, and 7 years before mechanical characterization. mechanical characterization.


Steps assumed for the conditioned waste matrix characterization in Steps assumed for the conditioned waste matrix characterization in simulated and real conditions:simulated and real conditions:

- preparation and mechanical characterization of reference - preparation and mechanical characterization of reference cemented matrices:cemented matrices:

Portland Cement + water, with a cement/water ratio 2:1;Portland Cement + water, with a cement/water ratio 2:1; - preparation of iron precipitates such as to:- preparation of iron precipitates such as to:

addition of the neutralization agents, NaOH(20%), to the diluted solution of addition of the neutralization agents, NaOH(20%), to the diluted solution of FeCl3(40%);FeCl3(40%);

addition of Na3PO4 to the diluted solution of FeCl3(40%);addition of Na3PO4 to the diluted solution of FeCl3(40%); - preparation and mechanical characterization of simulated sludge - preparation and mechanical characterization of simulated sludge

cemented matrices containing iron precipitates:cemented matrices containing iron precipitates: Portland cement + iron phosphate precipitate with cement / iron phosphate Portland cement + iron phosphate precipitate with cement / iron phosphate

ratio 1:0.5;ratio 1:0.5; Portland cement + iron hydroxide precipitate with cement / iron hydroxide Portland cement + iron hydroxide precipitate with cement / iron hydroxide

ratio 1:0.5ratio 1:0.5 - selection of real and simulated disposal conditions for cemented - selection of real and simulated disposal conditions for cemented

matrices;matrices; - emplacement of cemented matrices in Radioactive Waste - emplacement of cemented matrices in Radioactive Waste

National Repository Baita Bihor for real disposal characterization;National Repository Baita Bihor for real disposal characterization;


After the preparation, the samples of cemented matrices were After the preparation, the samples of cemented matrices were kept 24 hours in pattern, then in tight plastic bag for 7, 14 and 28 kept 24 hours in pattern, then in tight plastic bag for 7, 14 and 28 days for reinforcement. days for reinforcement.

After 28 days, the samples of cemented matrices were introduced After 28 days, the samples of cemented matrices were introduced in distillate water (laboratory conditions) and in the Radioactive in distillate water (laboratory conditions) and in the Radioactive Waste National Repository Baita-Bihor (real condition).Waste National Repository Baita-Bihor (real condition).

For the mechanical characterization tests the size of the samples For the mechanical characterization tests the size of the samples was 20x20x20 mm (tested at compression).was 20x20x20 mm (tested at compression).

The compression tests, performed on five samples, were done in a The compression tests, performed on five samples, were done in a construction material laboratory using an digital press machine construction material laboratory using an digital press machine type MATEST, with loading rates 1.2 MPa/stype MATEST, with loading rates 1.2 MPa/s


NoNo . . The point of disposal in The point of disposal in real conditionreal condition

Temperature Temperature [◦C][◦C]

Humidity [%]Humidity [%]

11 Position 1Position 1 1111 9898



44 Position 4Position 4 11.511.5 8585


Table 1 – Table 1 – The temperature and humidity conditions in the Radioactive Waste National Repository Baita- BihorThe temperature and humidity conditions in the Radioactive Waste National Repository Baita- Bihor


The results for samples disposal in real conditions will be The results for samples disposal in real conditions will be compared with the results obtained for the same type of compared with the results obtained for the same type of samples kept in laboratory conditions.samples kept in laboratory conditions.


1. XRD Analysis1. XRD Analysis

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Figure 1 - The x-ray diffractogram of hydrated cement

The XRD diffractogram of the hydrated cement emphasizes crystalline hydrated compounds as:

-tricalcium hydrosulfataluminate similar to the natural ettringite - Ca3Al2O6·3CaSO4·31H2O (2θ: 15.8; 19.2; 21.8; 35; 41), -calcium hydroxide – Ca(OH)2 well crystallized from the intergranular solution (2θ: 18; 34.2; 47.2; 50.6; 54.6), -the hexagonal calcium hydroaluminate - Ca4Al2O7·13H2O (2θ: 11.6; 33.6; 36)-tricalcium silicate – Ca3SiO5 (2θ: 29.5; 32.3; 51.8), -dicalcium silicate – Ca2SiO4 (2θ: 29.5; 32; 32.3) -tricalcium aluminate – Ca3Al2O6 which remain unreacted (2θ: 21.8; 32)


Due to the precipitates low crystallized, a part of the iron compounds present low and Due to the precipitates low crystallized, a part of the iron compounds present low and large lines. large lines.

The measurement done through XRD on the iron precipitate Fe(OH)3 confirmed the The measurement done through XRD on the iron precipitate Fe(OH)3 confirmed the existence of two types spinelic structures corresponding to magnetite (Fe3O4) and γ existence of two types spinelic structures corresponding to magnetite (Fe3O4) and γ Fe2O3 as well as to β Fe2O3·H2O and αFe2O3 compounds. Fe2O3 as well as to β Fe2O3·H2O and αFe2O3 compounds.

From the Fe(OH)3 x-ray diffractogram one can notice the appearance of a crystallized From the Fe(OH)3 x-ray diffractogram one can notice the appearance of a crystallized phase being present through well underlined peaks and of a amorphous phase phase being present through well underlined peaks and of a amorphous phase presenting very large and low peaks.presenting very large and low peaks.

Figure 2 - The x-ray diffractogram of iron hydroxideFigure 2 - The x-ray diffractogram of iron hydroxide

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At the precipitate FePO4 x-ray diffractogram one can notice that the iron phases present At the precipitate FePO4 x-ray diffractogram one can notice that the iron phases present a better crystalline namely there are presented more sharped peaks and with the a better crystalline namely there are presented more sharped peaks and with the higher intensities especially: higher intensities especially:

- iron hydrate orthophosphate - FePO4·2H2O, iron hydrate orthophosphate - FePO4·2H2O, - iron metaphosphate – Fe(PO2)2 iron metaphosphate – Fe(PO2)2 - iron hydrate phosphate – Fe4(PO4)2(OH)6·H2O. iron hydrate phosphate – Fe4(PO4)2(OH)6·H2O.

In the case of this iron precipitate can be noticed in the x-ray diffractogramIn the case of this iron precipitate can be noticed in the x-ray diffractogram the the

appearance of amorphous phase.appearance of amorphous phase.

Figure 3 - The x-ray diffractogram of iron phosphateFigure 3 - The x-ray diffractogram of iron phosphate

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The peaks characteristic of the hydrated cement compounds do not disappear, they The peaks characteristic of the hydrated cement compounds do not disappear, they presenting a very small decreasing of intensity of the lines specific to these presenting a very small decreasing of intensity of the lines specific to these compounds (Ca(OH)2, tricalcium hydrosulfataluminate – Ca3Al2O6·3CaSO4·31H2O, compounds (Ca(OH)2, tricalcium hydrosulfataluminate – Ca3Al2O6·3CaSO4·31H2O, calcium hydroaluminate – Ca4Al2O7·13H2O and calcium hydrosilicates like calcium hydroaluminate – Ca4Al2O7·13H2O and calcium hydrosilicates like tobermorite gel – Ca2SiO4·H2O). tobermorite gel – Ca2SiO4·H2O).

In this x-ray diffractogram appeared new compounds during the hardening of cement In this x-ray diffractogram appeared new compounds during the hardening of cement paste as a consequence of the chemical reactions between iron hydroxide and the paste as a consequence of the chemical reactions between iron hydroxide and the hydrated cement compounds: calcium iron oxide – β-Ca4Fe14O25 (2θ: 34.55; 34.21; hydrated cement compounds: calcium iron oxide – β-Ca4Fe14O25 (2θ: 34.55; 34.21; 33.30; 29.92), calcium iron silicate – Ca3Fe2(SiO4)3 (2θ: 33; 29.59; 36.45; 20.8), 33.30; 29.92), calcium iron silicate – Ca3Fe2(SiO4)3 (2θ: 33; 29.59; 36.45; 20.8), calcium aluminium iron oxide - Ca4Al2Fe2O10 (2θ: 34.09; 32.31; 47.34; 33.56). calcium aluminium iron oxide - Ca4Al2Fe2O10 (2θ: 34.09; 32.31; 47.34; 33.56).

These compounds belonging to the hydrated cement present an important role These compounds belonging to the hydrated cement present an important role concerning the hardening structure of the cement and the mechanical strength of the concerning the hardening structure of the cement and the mechanical strength of the concrete.concrete.

Figure 4 - The x-ray diffractogram of Figure 4 - The x-ray diffractogram of

cement - iron hydroxidecement - iron hydroxide

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Emphasizes the existence of some new compounds which appear after the Emphasizes the existence of some new compounds which appear after the chemical reactions between the cement and iron precipitate namely: chemical reactions between the cement and iron precipitate namely: phosphate hydroxide double of iron and calcium - phosphate hydroxide double of iron and calcium - Ca2Fe(PO4)2(OH)Ca2Fe(PO4)2(OH)1½H2O (its diffraction angle being: 29.2; 32.8; 34.6; 1½H2O (its diffraction angle being: 29.2; 32.8; 34.6; 25.6). 25.6).

Beside these new compounds, lower quantities of iron hydrate orthophosphate Beside these new compounds, lower quantities of iron hydrate orthophosphate -FePO4·2H2O unreactioned, can be identified. -FePO4·2H2O unreactioned, can be identified.

It is also emphasize the important presence of compounds from the hydrated It is also emphasize the important presence of compounds from the hydrated cement, but presenting a diminution of the Röentgen interferences cement, but presenting a diminution of the Röentgen interferences intensities specific to these compounds.intensities specific to these compounds.

Figure 5 - The x-ray diffractogram of Figure 5 - The x-ray diffractogram of

cement - iron phosphatecement - iron phosphate

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2. Mechanical tests2. Mechanical tests

The compression tests were done on the samples of cemented The compression tests were done on the samples of cemented matrices with sizes 20x20x20 mm.matrices with sizes 20x20x20 mm.

The samples were submitted of the mechanical tests after 28 days The samples were submitted of the mechanical tests after 28 days

and 1, 3, 5, 7 years disposal in the real and laboratory conditions.and 1, 3, 5, 7 years disposal in the real and laboratory conditions.

Preliminary results show that iron hydroxide and iron phosphate Preliminary results show that iron hydroxide and iron phosphate precipitate have a negative influence on the mechanical precipitate have a negative influence on the mechanical performances of cemented matrices.performances of cemented matrices.

In table 2 are presented values obtained for the compressive In table 2 are presented values obtained for the compressive strength on the cement: water matrices after 28 days, 1, 3, 5and 7 strength on the cement: water matrices after 28 days, 1, 3, 5and 7 years of disposal in real and laboratory conditions.years of disposal in real and laboratory conditions.


NoNo SampleSample Position Position Rcomp. Rcomp. (N/mm2(N/mm2 ) )

1. 1. Cement - water after 28 daysCement - water after 28 days 26.0 26.0

2. 2. Cement – water after one year disposal under distillate Cement – water after one year disposal under distillate water (laboratory conditions)water (laboratory conditions) 28.3 28.3

3.3. Cement – water after one year disposal in National Cement – water after one year disposal in National Repository of Radioactive Waste (realRepository of Radioactive Waste (real conditions)conditions) 11

3355

39.539.543.543.537.637.6

4.4. Cement – water after three years disposal under distillate Cement – water after three years disposal under distillate water (laboratory conditions) water (laboratory conditions) 51.3 51.3

5.5. Cement – water after three years disposal in National Cement – water after three years disposal in National Repository of Radioactive Waste (real conditions) Repository of Radioactive Waste (real conditions) 11

3355

55.355.359595656

6.6. Cement – water after five years disposal under distillate Cement – water after five years disposal under distillate water (laboratory conditions) water (laboratory conditions)

61.061.0 7.7. Cement – water after five years disposal in National Cement – water after five years disposal in National

Repository of Radioactive Waste (real conditions) Repository of Radioactive Waste (real conditions) 113355

63.563.572.072.063.063.0

8.8. Cement – water after five years disposal under distillate Cement – water after five years disposal under distillate water (laboratory conditions) water (laboratory conditions) 64 64

9.9. Cement – water after five years disposal in National Cement – water after five years disposal in National Repository of Radioactive Waste (real conditions) Repository of Radioactive Waste (real conditions) 11

3355

6969737366.766.7


System cement - water

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28 days 1 year 3 years 5 years 7 years

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laboratory conditions real conditions 1 real conditions 3 real conditions 5

The behaviour in time of the compressive strength for cement-water matrices is presented in figure 6.


In table 3 are presented values obtained for the compressive test on the cement: iron In table 3 are presented values obtained for the compressive test on the cement: iron hydroxide precipitate matrices after 28 days, 1, 3, 5and 7 years of disposal in real hydroxide precipitate matrices after 28 days, 1, 3, 5and 7 years of disposal in real and laboratory conditions.and laboratory conditions.

Figure 7 - The behaviour in time of compressive strength on the cement – Fe(OH)3Figure 7 - The behaviour in time of compressive strength on the cement – Fe(OH)3 matricesmatrices

System cement - Fe(OH)3

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No No SampleSample PositionPosition Rcomp.Rcomp.

(N/mm2)(N/mm2)

11 Cement – iron hydroxide precipitate after 28 days Cement – iron hydroxide precipitate after 28 days 22 22

22 Cement – iron hydroxide precipitate after one year disposal under Cement – iron hydroxide precipitate after one year disposal under distillate water (laboratory conditions ) distillate water (laboratory conditions )

23.41 23.41

33 Cement – iron hydroxide precipitate after one year disposal in Cement – iron hydroxide precipitate after one year disposal in National Repository of Radioactive Waste(real conditions) National Repository of Radioactive Waste(real conditions)

1 1 3 3 5 5

25.325.326.326.324.224.2

44 Cement – iron hydroxide precipitate after three years disposal under Cement – iron hydroxide precipitate after three years disposal under distillate water (laboratory conditions) distillate water (laboratory conditions)

25.375 25.375

55 Cement – iron hydroxide precipitate after three year disposal in Cement – iron hydroxide precipitate after three year disposal in National Repository of Radioactive Waste(real conditions) National Repository of Radioactive Waste(real conditions)

1 1 3 3 5 5

27.4527.4528.6528.6523.5323.53

66 Cement – iron hydroxide precipitate after five years disposal under Cement – iron hydroxide precipitate after five years disposal under distillate water (laboratory conditions ) distillate water (laboratory conditions )

29.1 29.1

77 Cement – iron hydroxide precipitate after five years disposal in Cement – iron hydroxide precipitate after five years disposal in National Repository of Radioactive Waste(real conditions) National Repository of Radioactive Waste(real conditions)

1 1 3 3 5 5

31.3731.3733.533.528.028.0

88 Cement – iron hydroxide precipitate seven years disposal under Cement – iron hydroxide precipitate seven years disposal under distillate water (laboratory conditions) distillate water (laboratory conditions)

37.6 37.6

99 Cement – iron hydroxide precipitate after seven years disposal in Cement – iron hydroxide precipitate after seven years disposal in National Repository of Radioactive Waste(real conditions) National Repository of Radioactive Waste(real conditions)

1 1 3 3 5 5

54.9554.9542.6242.6230.530.5


In table 4 are presented values obtained for the compressive test on the cement: iron In table 4 are presented values obtained for the compressive test on the cement: iron phosphate precipitate matrices after 28 days, 1, 3, 5and 7 years of disposal in real phosphate precipitate matrices after 28 days, 1, 3, 5and 7 years of disposal in real and laboratory conditionsand laboratory conditions

The behaviour in time of the compressive strength for cement-water matrices is The behaviour in time of the compressive strength for cement-water matrices is presented in figure 8.presented in figure 8.

System cement - FePO4

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11 Cement – iron phosphate precipitate after 28 days Cement – iron phosphate precipitate after 28 days 23.523.5

22 Cement – iron phosphate precipitate after one year disposal under Cement – iron phosphate precipitate after one year disposal under distillate water (laboratory conditions) distillate water (laboratory conditions)

25.225.2

33 Cement – iron phosphate precipitate after one years disposal in Cement – iron phosphate precipitate after one years disposal in National Repository of Radioactive Waste (real conditions) National Repository of Radioactive Waste (real conditions)

1 1 3 3 55

29.329.331.231.235.735.7

44 Cement – iron phosphate precipitate after three years disposal under Cement – iron phosphate precipitate after three years disposal under distillate water (laboratory conditions) distillate water (laboratory conditions)

38 38

55 Cement – iron phosphate precipitate after three years disposal in Cement – iron phosphate precipitate after three years disposal in National Repository of Radioactive Waste (real conditions) National Repository of Radioactive Waste (real conditions)

1 1 3 3 55

39.539.540.840.84343

66 Cement – iron phosphate precipitate after five years disposal under Cement – iron phosphate precipitate after five years disposal under distillate water (laboratory conditions) distillate water (laboratory conditions)

42.3 42.3

77 Cement – iron phosphate precipitate after five years disposal in Cement – iron phosphate precipitate after five years disposal in National Repository of Radioactive Waste (real conditions) National Repository of Radioactive Waste (real conditions)

1 1 3 3 55

45.3745.3746.7546.7548.048.0

88 Cement – iron phosphate precipitate seven years disposal under Cement – iron phosphate precipitate seven years disposal under distillate water (laboratory conditions) distillate water (laboratory conditions)

44.6 44.6

99 Cement – iron phosphate precipitate after seven years disposal in Cement – iron phosphate precipitate after seven years disposal in National Repository of Radioactive Waste (real conditions) National Repository of Radioactive Waste (real conditions)

1 1 3 3 55

52.6452.6452.4552.4554.254.2


Concluding remarksConcluding remarks : :

XRD analysisXRD analysis

The analyses of the simulated radioactive waste processing products by The analyses of the simulated radioactive waste processing products by x-rays diffraction proved that, despite of the investigated systems x-rays diffraction proved that, despite of the investigated systems complexity, the main phases could be identified. complexity, the main phases could be identified.

This study allowed the identification of the compounds that appear after This study allowed the identification of the compounds that appear after the interaction between the cement and the iron precipitates.the interaction between the cement and the iron precipitates.

The new results obtained concerning the embedding of the iron The new results obtained concerning the embedding of the iron compounds in cement offered large possibilities for a detailed compounds in cement offered large possibilities for a detailed characterization of the mechanism during the cementation process.characterization of the mechanism during the cementation process.

The XRD proved to be useful in the establishing of the composition and The XRD proved to be useful in the establishing of the composition and structure of the iron compounds used in the chemical treatment of the structure of the iron compounds used in the chemical treatment of the radioactive waste.radioactive waste.

In the future these data will be the reference data for structural and In the future these data will be the reference data for structural and mechanical characterization of the long term behaviour of these mechanical characterization of the long term behaviour of these matrices kept in condition simulating the final disposal.matrices kept in condition simulating the final disposal.


Mechanical testsMechanical tests

The compressive strength obtained for the samples which contain cement - The compressive strength obtained for the samples which contain cement - iron hydroxide and cement-iron phosphate are smaller than the reference iron hydroxide and cement-iron phosphate are smaller than the reference samples which contain cement-water but they are included in the accepted samples which contain cement-water but they are included in the accepted limits for the embedding matrix with cement (above 5N/mm2).limits for the embedding matrix with cement (above 5N/mm2).

The compressive strength for system with iron precipitates increase in time The compressive strength for system with iron precipitates increase in time and they are not influenced on the disposal conditions.and they are not influenced on the disposal conditions.

The results obtained by mechanical tests will be correlated with the The results obtained by mechanical tests will be correlated with the structural modifications (after three, five and seven years of disposal).structural modifications (after three, five and seven years of disposal).


Thank you !Thank you !

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