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Plutonium reactions with corroded Magnox sludge simulant

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Plutonium reactions with corroded Magnox sludge simulant

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    1. Plutonium reactions with corroded Magnox sludge simulant Thank Chair greet room. So I can get straight onto talking about our experiment and result Ive put most of the introduction onto the opening slide, with some pictures which Im sure most of you will have seen before This is one of a number of storage ponds where spent Magnox fuel rods are stored prior to being reprocessed, but corrosion of the Magnesium alloy fuel cladding leads to the formation of corroded Magnox sludge and here we can see some sedimented at the bottom of a pond, with some bare fuel rods where the cladding has completely corroded away. The sludge is contaminated with elements from the fuel and fission products. However, the main alpha contamination associated with the sludge is plutonium. So as part of an investigation to study general pond chemistry that may control Pu sorption onto CMS, we have performed a range of filtration experiments with Pu solutions and a CMS simulant and some other key reagents found in or added to the storage ponds. Good afternoon everyone today Im going to present the data from our study of corroded Magnox sludge formed in spent fuel storage pond, its chemical form, its interaction with plutonium, and the results from initial studies of the structure of cement for immobilisation of this waste.Thank Chair greet room. So I can get straight onto talking about our experiment and result Ive put most of the introduction onto the opening slide, with some pictures which Im sure most of you will have seen before This is one of a number of storage ponds where spent Magnox fuel rods are stored prior to being reprocessed, but corrosion of the Magnesium alloy fuel cladding leads to the formation of corroded Magnox sludge and here we can see some sedimented at the bottom of a pond, with some bare fuel rods where the cladding has completely corroded away. The sludge is contaminated with elements from the fuel and fission products. However, the main alpha contamination associated with the sludge is plutonium. So as part of an investigation to study general pond chemistry that may control Pu sorption onto CMS, we have performed a range of filtration experiments with Pu solutions and a CMS simulant and some other key reagents found in or added to the storage ponds. Good afternoon everyone today Im going to present the data from our study of corroded Magnox sludge formed in spent fuel storage pond, its chemical form, its interaction with plutonium, and the results from initial studies of the structure of cement for immobilisation of this waste.

    2. CMS characterisation Before we got onto the filter experiments we characterised the sludge simulant. So here is what the sludge is like when you allow it to settle and remove most of the supernatant a thick white paste. But with in solution the sludge appears more of a milk where the suspended particulate takes a few hours to settle. The sample is inactive but made from real Magnox allow. It was kindly provided by Nexia who made the sample by allowing Magnox swarf to corrode in a water filled silo open to air. We analysed the composition and morphology of the sample. X-ray diffraction and infrared ctrum of the sludge, and we find it to be composed of mainly brucite with some artinite present. The presence of artinite is interesting as since analysising the CMS sample, weve tried to prepare artinite from magnesium salts and metal and have only ever made brucite or other carbonate phase. So I think there is some interesting surface chemistry going on the surface of the Magnox to control the formation of artinte So an outline of the talk Ill first give some background to this study with a brief description of Magnox fuel storage ponds where this CMS waste were interested in cementing is generated. And then the Ive split the talk into 2. First Ill go over our characterisation of CMS and its interaction with Pu in the storage pond environment. And then Ill present our initial data on the structure of cements, similar to those that are intended for immobilisation of this CMS waste. Finally Ill end on the intended extension of this work.Before we got onto the filter experiments we characterised the sludge simulant. So here is what the sludge is like when you allow it to settle and remove most of the supernatant a thick white paste. But with in solution the sludge appears more of a milk where the suspended particulate takes a few hours to settle. The sample is inactive but made from real Magnox allow. It was kindly provided by Nexia who made the sample by allowing Magnox swarf to corrode in a water filled silo open to air. We analysed the composition and morphology of the sample. X-ray diffraction and infrared ctrum of the sludge, and we find it to be composed of mainly brucite with some artinite present. The presence of artinite is interesting as since analysising the CMS sample, weve tried to prepare artinite from magnesium salts and metal and have only ever made brucite or other carbonate phase. So I think there is some interesting surface chemistry going on the surface of the Magnox to control the formation of artinte So an outline of the talk Ill first give some background to this study with a brief description of Magnox fuel storage ponds where this CMS waste were interested in cementing is generated. And then the Ive split the talk into 2. First Ill go over our characterisation of CMS and its interaction with Pu in the storage pond environment. And then Ill present our initial data on the structure of cements, similar to those that are intended for immobilisation of this CMS waste. Finally Ill end on the intended extension of this work.

    3. CMS characterisation When we look at the sample in the environmental scanning electon microscope we see large, platy crystals typical of brucite; and needle-like crystals, some with a radial morphology typical of artinite. And the EDAX X-ray analysis back up this identification. In addition we get a lot of this small aggregated material, which appears to be a mixed of brucite and artinite, but as for the bulk mainly brucite. For our experiments we wanted to examine the associative behaviour of Pu for the fractions of CMS that were likely to be most mobile in the ponds ie the smaller particulate. Therefore, we allowed 3 hours settling time for the suspension and used the supernatant in the experiments. So we could determine the particulate present we ultrafiltered some of this supernatant fraction and looked at that under the ESEM. So an outline of the talk Ill first give some background to this study with a brief description of Magnox fuel storage ponds where this CMS waste were interested in cementing is generated. And then the Ive split the talk into 2. First Ill go over our characterisation of CMS and its interaction with Pu in the storage pond environment. And then Ill present our initial data on the structure of cements, similar to those that are intended for immobilisation of this CMS waste. Finally Ill end on the intended extension of this work.When we look at the sample in the environmental scanning electon microscope we see large, platy crystals typical of brucite; and needle-like crystals, some with a radial morphology typical of artinite. And the EDAX X-ray analysis back up this identification. In addition we get a lot of this small aggregated material, which appears to be a mixed of brucite and artinite, but as for the bulk mainly brucite. For our experiments we wanted to examine the associative behaviour of Pu for the fractions of CMS that were likely to be most mobile in the ponds ie the smaller particulate. Therefore, we allowed 3 hours settling time for the suspension and used the supernatant in the experiments. So we could determine the particulate present we ultrafiltered some of this supernatant fraction and looked at that under the ESEM. So an outline of the talk Ill first give some background to this study with a brief description of Magnox fuel storage ponds where this CMS waste were interested in cementing is generated. And then the Ive split the talk into 2. First Ill go over our characterisation of CMS and its interaction with Pu in the storage pond environment. And then Ill present our initial data on the structure of cements, similar to those that are intended for immobilisation of this CMS waste. Finally Ill end on the intended extension of this work.

    4. CMS characterisation And we see that same brucite and artinite and small aggregated material but as youd expect there is are no large crystals or particulate. So an outline of the talk Ill first give some background to this study with a brief description of Magnox fuel storage ponds where this CMS waste were interested in cementing is generated. And then the Ive split the talk into 2. First Ill go over our characterisation of CMS and its interaction with Pu in the storage pond environment. And then Ill present our initial data on the structure of cements, similar to those that are intended for immobilisation of this CMS waste. Finally Ill end on the intended extension of this work.And we see that same brucite and artinite and small aggregated material but as youd expect there is are no large crystals or particulate. So an outline of the talk Ill first give some background to this study with a brief description of Magnox fuel storage ponds where this CMS waste were interested in cementing is generated. And then the Ive split the talk into 2. First Ill go over our characterisation of CMS and its interaction with Pu in the storage pond environment. And then Ill present our initial data on the structure of cements, similar to those that are intended for immobilisation of this CMS waste. Finally Ill end on the intended extension of this work.

    5. Plutonium and CMS experiments So here is what the sludge is like when you allow it to settle and remove most of the supernatant a thick white paste. The sample is inactive but made from real Magnox allow. It was kindly provided by Nexia who allowed swarf to corrode in a water filled silo open to air. So an outline of the talk Ill first give some background to this study with a brief description of Magnox fuel storage ponds where this CMS waste were interested in cementing is generated. And then the Ive split the talk into 2. First Ill go over our characterisation of CMS and its interaction with Pu in the storage pond environment. And then Ill present our initial data on the structure of cements, similar to those that are intended for immobilisation of this CMS waste. Finally Ill end on the intended extension of this work.So here is what the sludge is like when you allow it to settle and remove most of the supernatant a thick white paste. The sample is inactive but made from real Magnox allow. It was kindly provided by Nexia who allowed swarf to corrode in a water filled silo open to air. So an outline of the talk Ill first give some background to this study with a brief description of Magnox fuel storage ponds where this CMS waste were interested in cementing is generated. And then the Ive split the talk into 2. First Ill go over our characterisation of CMS and its interaction with Pu in the storage pond environment. And then Ill present our initial data on the structure of cements, similar to those that are intended for immobilisation of this CMS waste. Finally Ill end on the intended extension of this work.

    6. Plutonium and CMS experiments The first set of result we collected showed the amount of plutonium filtered from solution over a range of CMS concentrations from pH 10.8 to 11.5. The results show a strong correlation between the amount of Pu filtered and CMS concentration. The results also show more Pu is filtered at high pH likely due to precipitation of more brucite at high pH or The first set of result we collected showed the amount of plutonium filtered from solution over a range of CMS concentrations from pH 10.8 to 11.5. The results show a strong correlation between the amount of Pu filtered and CMS concentration. The results also show more Pu is filtered at high pH likely due to precipitation of more brucite at high pH or

    7. Plutonium and CMS experiments So here is what the sludge is like when you allow it to settle and remove most of the supernatant a thick white paste. The sample is inactive but made from real Magnox allow. It was kindly provided by Nexia who allowed swarf to corrode in a water filled silo open to air. So an outline of the talk Ill first give some background to this study with a brief description of Magnox fuel storage ponds where this CMS waste were interested in cementing is generated. And then the Ive split the talk into 2. First Ill go over our characterisation of CMS and its interaction with Pu in the storage pond environment. And then Ill present our initial data on the structure of cements, similar to those that are intended for immobilisation of this CMS waste. Finally Ill end on the intended extension of this work. So from our previous studies on this system we looked at how plutonium interacts with CMS in solution at a number of pHs and with the interaction of a number of possible reagents with the storage pond / effluent treatment plant environment. After performing filtration experiments we found that plutonium shows a strong affinity to CMS in solution even at low concentrations. In our experiments were Pu was present in 10 micromolar concentrations and CMS was present at 3 ppm, So here is what the sludge is like when you allow it to settle and remove most of the supernatant a thick white paste. The sample is inactive but made from real Magnox allow. It was kindly provided by Nexia who allowed swarf to corrode in a water filled silo open to air. So an outline of the talk Ill first give some background to this study with a brief description of Magnox fuel storage ponds where this CMS waste were interested in cementing is generated. And then the Ive split the talk into 2. First Ill go over our characterisation of CMS and its interaction with Pu in the storage pond environment. And then Ill present our initial data on the structure of cements, similar to those that are intended for immobilisation of this CMS waste. Finally Ill end on the intended extension of this work. So from our previous studies on this system we looked at how plutonium interacts with CMS in solution at a number of pHs and with the interaction of a number of possible reagents with the storage pond / effluent treatment plant environment. After performing filtration experiments we found that plutonium shows a strong affinity to CMS in solution even at low concentrations. In our experiments were Pu was present in 10 micromolar concentrations and CMS was present at 3 ppm,

    8. Plutonium and CMS experiments Effect of Silica - added as sodium silicate - 1 ppm Effect of silicaEffect of silica

    9. Plutonium and CMS experiments Effect of polyelectrolyte - Magnafloc - 0.35 ppm Effect of polyelectrolyteEffect of polyelectrolyte

    10. Plutonium and CMS experiments Effect of CMS - Simulant from Magnox alloy - 3 ppm Effect of cmsEffect of cms

    11. Plutonium and CMS experiments Effect of treatmentsEffect of treatments

    12. Plutonium and CMS experiments Summary CMS - artinite and brucite - Pu associated with sludge Pu filtration influenced by: - Carbonate, CO32- (Na2CO3) - Polyelectrolyte - CMS - Treatment / pH conditions Summary slide best pond condition to minimise Pu mobilitySummary slide best pond condition to minimise Pu mobility

    13. Neil Milestone University of Sheffield Chris Eaves & Andy Fellerman Nexia Solutions Thank you for your attention Acknowledgements

    14. Spent Magnox fuel rods stored in large water-filled storage ponds Pond maintained at high pH to minimise corrosion of the fuel rods magnesium-alloy cladding However, cladding easily corroded in aqueous environment and large quantity of corroded sludge has accumulated (primarily at Sellafield site) Include: ponds constantly purged to limit organic and carbonate concentrationsInclude: ponds constantly purged to limit organic and carbonate concentrations

    15. Pu association with CMS Pu found to associate with CMS particulate / colloid (Kd = 1.5 x 106 ml/g) CMS within storage pond contaminated with particles of spent fuel and Pu sorbed from the pond liquor. So from our previous studies on this system we looked at how plutonium interacts with CMS in solution at a number of pHs and with the interaction of a number of possible reagents with the storage pond / effluent treatment plant environment. After performing filtration experiments we found that plutonium shows a strong affinity to CMS in solution even at low concentrations. In our experiments were Pu was present in 10 micromolar concentrations and CMS was present at 3 ppm, Median and inter-quartile rangeSo from our previous studies on this system we looked at how plutonium interacts with CMS in solution at a number of pHs and with the interaction of a number of possible reagents with the storage pond / effluent treatment plant environment. After performing filtration experiments we found that plutonium shows a strong affinity to CMS in solution even at low concentrations. In our experiments were Pu was present in 10 micromolar concentrations and CMS was present at 3 ppm, Median and inter-quartile range

    16. Synchrotron time-resolved XRD experiment Weve been successful in obtaining synchrotron beamtime to study the reaction of brucite with the atmosphere and carbonate saturated solution.Weve been successful in obtaining synchrotron beamtime to study the reaction of brucite with the atmosphere and carbonate saturated solution.

    17. Time-resolved Energy-dispersive XRD results

    18. Time-resolved study continued Mention that more data recently been collected over greater temperature range with pH controlled with hydroxide. More time coming up.Mention that more data recently been collected over greater temperature range with pH controlled with hydroxide. More time coming up.

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