Abstract intended for Symposium on Recycling of metals, April 8-10, 2014, Studsvik

Nuclide distribution in the metal recycling process

Per Lidar, Maria Lindberg, Patrik Konneus and Arne Larsson, Studsvik Nuclear AB

The Studsvik metal melting facility has been in operation since 1987 for segmentation, decontamination and melting as well as recycling of free releasable metals, but also for conditioning of the secondary waste and metals treated for volume reduction only. By using the Studsvik scrap metal processing facility thousands of tons of metallic low level waste has been annually processed.

This paper gives an overview of the nuclide distribution for material that has been treated, illustrating differences between different waste origins, properties of the objects and its contamination as well as between different metals.

To allow that the metals after treatment can be subject for free release the regulatory framework and current operating licenses requires validated processes. Thanks to this the knowledge about the nuclide distribution in the processes is extensive.

Studsvik has collected all data for the material treated over the years in a data base, and the paper gives examples of how the nuclides will be distributed through the metal recycling process, allowing the possibility to predict the nuclide content in the metal ingots as well as in the secondary waste that needs to be conditioned as radioactive waste for disposal.

The paper also compares and discusses the nuclide distribution with literature data on the topic.

Symposium on Recycling of metals, April 8-10, 2014, Studsvik

The Metal Recycling Process and its Nuclide Distribution

Per Lidar*, Maria Lindberg*, Arne Larsson*, and Patrik Konneus* * Studsvik Nuclear AB SE-611 82 Nyköping Sweden [email protected]

ABSTRACT The Studsvik metal melting facility has been in operation since 1987 for segmentation, decontamination and melting. Thousands of tonnes of metallic low level waste have been processed with the aim of clearance. The nuclide distribution in the ingots of carbon and stainless steel, aluminium, and, lead has been analysed:

Carbon and stainless steel • 27 700 tonne treated • Co-60 is the totally dominating nuclide in the ingots (>96%), low energy emitting beta nuclides excluded

Aluminium • 800 tonne treated • Co-60 is dominating measured nuclide in the ingots with >60%, low energy emitting beta nuclides excluded

Lead • 400 tonne treated • Sr-90 is dominating measured nuclide with >50%, low energy emitting beta nuclides excluded

For 5 200 tonne of the melted carbon and stainless steel, the nuclide distribution in ingots and its secondary waste was investigated in detail with the following confirmations and result: • The data available was found to be enough to perform a relevant analyze • It confirms literature data regarding nuclide distribution in the melting process • Nuclide distribution in ingots, slag, and, dust from decades of melting in Studsvik for selected nuclides was summarized in a table • Forms an initial platform for development of more precise nuclide transfer models for the melting process.

The main conclusion is that an extensive amount of high quality data exist and that that it is feasible to develop improved models for the nuclide distribution during the melting process based on further analysis of these data and the experience built up.

INTRODUCTION Melting of contaminated metallic low level waste from the nuclear industry, as well as other operations involving or generating radioactive isotopes, for release from regulatory control and recycling is an established treatment method.

The nuclide vectors differ between different types of facilities:  NPP BWR and PWR primary circuit standard operation without significant fuel failures o Dominant contaminants activation products are Co-60, Ni-63 and Fe-55

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Symposium on Recycling of metals, April 8-10, 2014, Studsvik

 NPP with fuel failure history o Also fission products such as Cs-137, Sr-90, and certain alpha emitting nuclides have to be considered as a significant part of the nuclide inventory  Fuel factories o Uranium isotopes and its progeny o TRU-elements and activation products (mainly for MOX plants)  Research facilities (LWR, HWR, Spallation sources) o A wide combination of nuclides can exist

The variation in nuclide composition lead to that specific and reliable knowledge about the nuclide distribution in the material sent for treatment as well as during the metal recycling process is essential for all involved parties up to and including the repository owner.

Background There is an increased focus on the nuclide inventory in the secondary waste resulting from the treatment of metals.

There also seems to be a large conservatism, due to uncertainty, in assigned inventory for metals sent for treatment by melting. This may cause incorrect decisions in the different process steps and costly overestimations of the inventory in the residues sent for disposal, resulting in theoretically filling the repository with radionuclides before it is really full.

Decommissioning projects could be better optimized with  Less conservative nuclide inventories  Better knowledge of the transfer of nuclides during melting.

Purpose The purpose of this work was to investigate and understand the real nuclide distribution in the melting process in order to  Obtain a good characterization of the inventory  Support the clearance process of the ingots  Create less conservative nuclide vectors for the secondary waste  Give better guidelines to decommissioning projects.

Goal The goal is to establish an accepted formula for the nuclide distribution during the melting process.

METAL RECYCLING PROCESS Melting is suitable for low level waste with all types of contaminations. The target is to capture separated radioactivity either in the slag or in the off-gas treatment system. Nuclides in gas phase at room temperature lead to special requirements for the off-gas treatment.

For the melting, established techniques and facilities are available. Melting of scrap metal has been performed and developed over the centuries and there is a continuous development going on both within the conventional steel industry but also for applications on contaminated metals. For applications on metals contaminated with radionuclides international guidelines and recommendations exists such as EC RP89 [1] regarding conditional clearance of ingots after melting.

The need and interest for melting services has increased significantly over the years. To meet the market as well as regulatory demand several facility upgrades and extensions have been made to the melting facility at Studsvik. Today the licensed capacity is 5 000 tonnes

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Symposium on Recycling of metals, April 8-10, 2014, Studsvik

per year. Two induction furnaces are used at the facility; one can be seen in Figure 1.

To allow that the metals, after treatment, can be subject to clearance the regulatory framework and current operating licenses requires validated processes. The extensive knowledge in metal melting and the nuclide distribution in the processes has been an important parameter in this validation process.

Studsvik has all data for the material treated over the decades in a data base, and this paper gives examples of how nuclides will be distributed through the metal recycling process, allowing the possibility to predict the nuclide transfer to the metal ingots as well as to the different fractions of the secondary waste generated in the process.

Fig.1. Induction furnace at Studsvik for melting ingots of contaminated metallic low level waste.

MATERIAL DIFFERENCES IN NUCLIDE DISTRIBUTION The nuclide distribution in the melting process is to certain degree material specific. Based on this material specific knowledge the pre-treatment efforts (steel shot blasting etc.) can be optimized. Generally, the following has been observed, see also Table I:  Carbon and stainless steel • Co, Mn, Fe, Ag and Ni isotopes are closely linked to the steel matrix and stays therefore to a high degree in the metal (the ingot) • Heavy elements (U, Am, Pu) are likely to be transferred to the slag (either automatically or by certain special treatment) • Substances which evaporates at the actual metal bath temperature are transferred to the slag or the dust (Cs etc.).  Aluminium • Co stays in the metal • Most heavy elements (U, Am, Pu) stays in the metal to a high degree • Nuclides which evaporates at the actual metal bath temperature are transferred to the slag or the dust.  Lead • Most isotopes, including Co, can be removed from the metal

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Symposium on Recycling of metals, April 8-10, 2014, Studsvik

• Co end up in the slag • Certain elements such as silver (Ag) are difficult to separate in the melting process • Heavy elements (U, Am, Pu) ends up in the slag to a high degree • Nuclides which evaporates at the actual temperature are transferred to the slag or the dust • Special personnel safety arrangements are mandatory when handling lead.

TABLE I. Overview– Nuclide distribution for most important nuclides in steel, excerpt from Table 6.2 in [2] which includes data from different sources. Nuclide Steel Slag Dust Other (%) (%) (%) (%) Mn-54 24-100 1-75 0-5 0

Co-60 20-100 0-1 0-80 0

Zn-65 0-20 0-1 80-100 0

Sr-90 0-20 95-100 0-10 0 Ag-108m 75-100 0-1 0-25 1 (bottom)

Sb-125 60-100 0-20 10-40 0

Cs-137 0 0-5 95-100 0

U 0-1 95-100 0-5 0 Pu 0-1 95-100 0-5 0

Am-241 0-1 95-100 0-5 0

Figure 2 shows a histogram over conditionally cleared ingots produced at Studsvik 2005 – 2012, in total approx. 10 000 tonnes are included. The large majority of the ingots have a low clearance quotai which indicates a margin to the allowed clearance quota of 1, but it says nothing about the nuclide distribution.

Fig. 2. Clearance quota vs. tonne conditionally cleared ingots produced at Studsvik 2005 – 2012.

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Symposium on Recycling of metals, April 8-10, 2014, Studsvik

RESULTS, NUCLIDE DISTRIBUTION IN INGOTS AND SECONDARY WASTE The results of the nuclide distribution in the ingots melted at Studsvik of carbon and stainless steel, aluminum and lead is shown in Table II. The dominant nuclides from measurements are listed as percentage of total activity. Samples from all ingots are measured with gamma spectrometry, and most of the ingots (depending on the origin) are also analyzed by alpha spectrometry.

TABLE II. Measured nuclide content for ingots melted at Studsvik for some material categories.

Material Weight, category tonne Measured nuclide content, % of total activity Other CS and SS** 27 749 Co-60 Mn-54 Sb-125 Zn-65 Ag-110m Ru-106 Uranium alpha Others 96% 1.1% 0.7% 0.5% 0.3% 0.3% 0.2% 0.1% 0.4%

Aluminium* 772 Co-60 Zn-65 Uranium Mn-54 Cs-137 Cr-51 Na-22 Sb-125 Others 62% 11% 6.4% 5.6% 4.6% 4.2% 1.4% 1.1% 2.8%

Lead* 395 Sr-90 Ag-110m Cs-137 Co-60 Ag-108m Am-241 Pu-239 Sb-125 Others 52% 17% 5.8% 5.5% 5.0% 3.9% 3.1% 1.3% 6.3% *) Minimum detectable activity ((MDA) values are included from gamma / alpha spectrometry. **) Carbon Steel (CS); Stainless Steel (SS).

The melting results in Table II show the following regarding material differences:

Carbon and stainless steel • Total amount melted and analysed is 27 700 tonne • Includes ingots for direct clearance and under decay storage prior to clearance (94% of the total tonnage) • Nuclide distribution in ingots – Co-60 >96% of all activity, low energy emitting beta nuclides excluded – Top six nuclides corresponds to 99%

Aluminium • Total amount melted and analysed is nearly 800 tonne • Includes ingots for direct clearance and under decay storage prior to clearance (85% of the of the total tonnage) • Nuclide distribution – Co-60 dominating with >60%, low energy emitting beta nuclides excluded – Top six nuclides corresponds to 95%

Lead • Total amount melted and analysed is about 400 tonne • All ingots were subject for clearance and included in the table • Nuclide distribution – Sr-90 is dominating with >50%, low energy emitting beta nuclides excluded – Top six nuclides corresponds to 89%

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Symposium on Recycling of metals, April 8-10, 2014, Studsvik

– The limited amount of lead treated coming from a limited number of facilities gives an uncertainty in the results.

For carbon and stainless steel, since Co-60 and Cs-137 are the dominating gamma emitting nuclides as well as correlation nuclides for hard to measure nuclides, it was decided to initially concentrate further analyses on these two nuclides. 5 200 tonne material from different LWRs were analysed with regards to the relation of activity in pre-treatment residues / ingots / slag / dust. The result is shown in Table III. Containerized scrap, i.e. scrap from maintenance or decommissioning activities, and large components are separated. The minimum, maximum and median values of the measured activity fraction in the ingots, dust and slag are listed.

As can be seen in Table III, there seems to be a difference between the nuclide distributions of Co-60 and Cs-137 in steel recycling from containerized scrap respectively large components. The difference could be a result of several factors, such as different surface to volume relationship between incoming waste in the groups, and differences in the effectiveness of pre-melting decontamination.

It should be noted that the measured activity is based on gamma and alpha spectrometry. Hard to measure nuclides (such as low energy beta emitters) are not measured in the metal, but is rarely any issue for the conditional clearance of ingots since the clearance values are so high compared to the ones for Co-60. However, the distribution of the pure beta emitters has to be known and considered, since the long lived nuclides can be important for the disposal long term safety case.

TABLE III. Nuclide distribution of Co-60 and Cs-137 in carbon and stainless steel recycling at Studsvik.

Co-60 Cs-137 Container scrap Max* Min* Median** Container scrap Max* Min* Median** Blasting residues 91% 18% 69% Blasting residues 16% 1% 14%

Distribution of the remaining activity in the melting Distribution of the remaining activity in the melting process: process:

Melting fraction Ingots 92% 29% 67% Melting fraction Ingots 0% 0% 0% Dust 58% 6% 24% Dust 70% 23% 57% Slag 14% 2% 4% Slag 77% 30% 52%

Large components Max Min Median Large components Max Min Median Blasting residues 82% 14% 46% Blasting residues 35% 10% 20%

Distribution of the remaining activity in the melting Distribution of the remaining activity in the melting process: process:

Melting fraction Ingots 99% 88% 97% Melting fraction Ingots 0% 0% 0% Dust 7% 0% 2% Dust 29% 10% 15% Slag 6% 1% 2% Slag 90% 71% 85% *) The max and min values are average values for each delivery. **) The sum of median values may not end of to 100% due to limited number of deliveries compared.

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Symposium on Recycling of metals, April 8-10, 2014, Studsvik

To visualize the overall nuclide distribution of the Table III data, the median values are re- scaled to achieve a total sum of 100%, and shown as graphs in Figure 3. For the metal recycling process, Figure 3 indicates, together with the results of Figure 2 and Table II, that for  Co-60 o Melting in combination with blasting and pre melting actions is effective.  Cs-137 o Melting is the outstanding most effective individual step, and can be used in combination with blasting and pre melting actions.

Co-60, container scrap Cs-137, container scrap

Blasting residues Ingots Blasting residues Ingots Dust (melting) Slag (melting) Dust (melting) Slag (melting)

Co-60, large components Cs-137, large components

Pre melting Ingots Pre melting Ingots Dust (melting) Slag (melting) Dust (melting) Slag (melting)

Fig.3. Nuclide distribution during the melting process. Examples given for Co-60 and Cs-137, divided into container scrap resp. large components.

LITERATURE COMPARISON The literature comparison is primarily made against two references [2, 3], see Table IV. The first reference [2] is applicable to steel. In Table 6.2 information is combined from different sources (Cheng et al., 2000; Nieves et al., 1995; NRC, 1999), leading to large uncertainty for some nuclides. Different furnace types (basic oxygen furnace and electrical arc furnace) are included in the compilation.

The second reference [3] is reflecting the experience from a facility in Germany and is applicable to steel. Detailed nuclide distribution for many nuclides is provided.

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Symposium on Recycling of metals, April 8-10, 2014, Studsvik

The median values taken from Table III are re-scaled in Table IV to achieve a total sum of 100%.

TABLE IV. Comparison of literature and Studsvik data of nuclide distribution during metal recycling process (carbon and stainless steel). Nuclide Ref. Note Steel (%) Slag(%) Dust (%) Other (%) Co-60 [2] 20-100 0-1 0-80 0 [3] 88 11 1 0 Container Min - Max 29-92 2-14 6-58 0 Container Median* 70 4 26 0 LC Min – Max 88-99 1-6 0-7 0 LC Median* 96 2 2 0 Cs-137 [2] 0 0-5 95-100 0 [3] <1 60 40 0 Container Min - Max 0-<1 30-77 23-70 0 Container Median* 0 47 53 0 LC Min - Max 0-<1 71-90 10-29 0 LC Median* 0 85 15 0 *) Median value re-scaled to 100% total sum.

CONCLUSION Studsvik has for more than three decades treated and melted mainly carbon and stainless steel but also aluminium, copper, brass and lead. Over the years has an extensive experience been built and data been collected.

Based upon an analysis of the extensive dataset it has been shown that it is feasible to develop improved models for the nuclide distribution during the melting process based on analysis of these data and the experience built up. This is important in order to support both waste generators and disposal organisations in their task to optimise their processes without violating the short or long term safety.

REFERENCES 1. Radiation protection 89, recommended radiological protection criteria for the recycling of metals from the dismantling of nuclear installations, European Commission, 1998.

2. NCRP (2002). Managing Potentially Radioactive Scrap Metal, NCRP Report No 141, NCRP, Bethesda, MD.

3. QUADE, U. and MÜLLER, W. (2005). Recycling of radioactively contaminated scrap from the nuclear cycle and spin-off for other application, Rev. Metal. Madrid Vol. Extr. (2005) 23-28.

1 In a practical case with more than one radionuclide involved, the clearance quota is defined as follows (Ref.: European Commission Radiation Protection 89):

To determine if a mixture of radionuclides is below the clearance level a summation formula is used:

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Symposium on Recycling of metals, April 8-10, 2014, Studsvik

푛 푐 ∑ 푖 < 1.0 푐 푖=1 퐿푖 where ci is the specific activity of radionuclide i in the material being considered (Bq/g and Bq/cm2), cLi is the specific clearance level of radionuclide i in the material (Bq/g and Bq/cm2), n is the number of radionuclides in the mixture.

In the above expression, the ratio of the concentration of each radionuclide to the clearance level is summed over all radionuclides in the mixture. If the sum (clearance quota) is less than one the material complies with the clearance requirements.

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The Metal Recycling Rank the Process and its picture below the Core Slide title Nuclide Distribution template slide 36pt

Slide subtitle Per Lidar, Maria Lindberg, Arne 18pt Larsson and Patrik Konneus

MR2014 April 8 - 10, 2014 Slide title pt Agenda

Text • Introduction 24 pt Bullets level 2 • Background 20 pt • Purpose • Goal • Metal recycling process • Material differences in nuclide distribution • Results, nuclide distribution in ingots • Literature comparison • Conclusion Slide title pt Background

Text • Increasing documentation requirements for disposed secondary waste 24 pt remaining after treatment for free release Bullets level 2 20 pt • Large conservatism in assigned nuclide vectors for radioactive waste intended for treatment for free release by melting • Poor forecasting capabilities • Dismantling work during decommissioning could be better optimized with • Less conservative nuclide vectors • Better knowledge of the real outcome from melting • More waste could therefore be subject for treatment and free release Slide title pt Purpose

Text • Investigate the real nuclide distribution in ingots melted at 24 pt Bullets level 2 Studsvik and its secondary waste in order to 20 pt • Obtain a good characterization of the inventory • Support the free release process of the ingots • Create less conservative and more precise nuclide vectors including the secondary waste • Give better guidelines to decommissioning projects and dismantling work Slide title pt Goal

Text • Establish an accepted formula for the nuclide distribution 24 pt Bullets level 2 during the melting process 20 pt • Revise the WAC for the Melting facility to allow for a wider scope of waste to be treated for free release Slide title pt Introduction – Expected nuclide vectors

 NPP BWR and PWR primary circuit standard operation without Text 24 pt significant fuel failures Bullets level 2 20 pt o Dominant contaminants activation products are Co-60, Ni-63 and Fe-55  NPP with fuel failure history o Also fission products such as Cs-137, Sr-90, and certain alpha emitting nuclides have to be considered as a significant part of the nuclide inventory  Fuel factories o Uranium isotopes and its progeny o TRU-elements and activation products (mainly for MOX plants)  Research facilities (LWR, HWR, Spallation sources) o A wide combination of nuclides can exist Slide title pt Metal recycling process

Text • Melting is suitable for low level • Melting facility at Studsvik since 24 pt waste with all types of 1987 Bullets level 2 20 pt contaminations • Licensed capacity 5 k tonne per y • Both short lived and long lived • Induction furnaces nuclides can be treated • Nuclides in vapor phase at room temperature lead to special requirements for the off-gas treatment • Established techniques and facilities available • International recommendation exists • EC RP89 Slide title pt Carbon and stainless steel

Text • Co, Mn, Fe, Ag and Ni isotopes are closely linked to the 24 pt Bullets level 2 steel matrix and stays therefore to a high degree 20 pt • Heavy alpha isotopes (U, Am, Pu) will end up in the slag to a high degree • Nuclides which evaporates at the actual temperature are transferred to the slag or the dust (Cs etc.) Slide title pt Aluminium

Text 24 pt Bullets level 2 20 pt • Co stays in the metal • Heavy alpha isotopes (U, Am, Pu) stays in the metal to a high degree • Nuclides which evaporates at the actual temperature are transferred to the slag or the dust Slide title pt Lead

Text • Most isotopes can be removed from the metal 24 pt Bullets level 2 20 pt • Co end up in the slag • Certain nuclides such as Ag-108m are hard to separate in the melting process • Heavy alpha isotopes (U, Am, Pu) ends up in the slag to a high degree • Nuclides which evaporates at the actual temperature are transferred to the slag or the dust • Special personnel safety case when handling lead melting! Slide title pt Overview– most important nuclides [1]

Nuclide Mode (α β γ) T1/2 Steel (%) Slag (%) Dust (%) Other (%) H-3 β 12.33 y

Text C-14 β 5730 y 27-100 0-1 0-2 0-73 (offgas) 24 pt Mn-54 β + γ 312 d 24-100 1-75 0-5 0 Bullets level 2 Co-60 β + γ 5.27 y 20-100 0-1 0-80 0 20 pt Zn-65 β + γ 244 d 0-20 0-1 80-100 0 Sr-90 β 28.79 y 0-20 95-100 0-10 0 Ag-108m β + γ 418 y 75-100 0-1 0-25 1 (bottom) Ag-110m β + γ 249 d Sb-125 β + γ 2.76 y 60-100 0-20 10-40 0 Cs-137 β + γ 30.07 y 0 0-5 95-100 0 U-234 α 2.4E+5 y 0-1 95-100 0-5 0 U-235 α + γ 7.0E+8 y U-238 α (+ γ) 4.5E+9 y Pu-238 α 87.7 y 0-1 95-100 0-5 0 Pu-239 α 24 110 y Am-241 α + γ 432 y 0-1 95-100 0-5 0 Slide title Histogram over conditionally cleared pt ingots 2005-2012. Approx. 10 000 tonne

Text Carbon and stainless steel 24 pt Bullets level 2 20 pt

The nuclide distribution? Slide title pt Results, nuclide distribution in ingots

Text Material Weight, 24 pt category tonne Measured nuclide content, % of total activity* Bullets level 2 20 pt CS and SS 27 749 Co-60 Mn-54 Sb-125 Cs-137 Zn-65 Ag-110m Ru-106 Total alpha Others 96% 1.1% 0.7% 0.7% 0.5% 0.3% 0.3% 0.3% 0.5% (MDA)

Aluminium 772 Co-60 Zn-65 Uranium Mn-54 Cs-137 Cr-51 Na-22 Sb-125 Others 62% 11% 6.4% 5.6% 4.6% 4.2% 1.4% 1.1% 2.8%

Lead 395 Sr-90 Ag-110m Cs-137 Co-60 Ag-108m Am-241 Pu-239 Sb-125 Others 52% 17% 5.8% 5.5% 5.0% 3.9% 3.1% 1.3% 6.3% *) MDA values included from gamma / alpha spectrometry. Slide title pt Material differences, melting results

Text • Carbon and stainless steel 24 pt Bullets level 2 – Total amount melted 27 700 tonne 20 pt – Includes ingots for direct free release and under decay storage – Nuclide distribution in ingots • Co-60 >95% of all activity – Since Co-60 is totally dominant nuclide and Cs-137 is important to measure, it was decided to concentrate the detailed study on Co-60 and Cs-137 • 5 200 tonne included for the relation of nuclides in ingots / slag / dust Slide title pt Material differences, metals recycling

Text • Carbon and stainless steel 24 pt – 5 200 tonne from different LWRs Bullets level 2 20 pt – Median levels adds up to 100% reasonably well Co-60. Cs-137 Container scrap Max Min Median Container scrap Max Min Median Blasting residues 91% 18% 69% Blasting residues 16% 1% 14%

Melting fraction Ingots 92% 29% 67% Melting fraction Ingots 0% 0% 0% Dust 58% 6% 24% Dust 70% 23% 57% Slag 14% 2% 4% Slag 77% 30% 52%

Large components Max Min Median Large components Max Min Median Pre melting fraction 82% 14% 46% Pre melting fraction 35% 10% 20%

Melting fraction Ingots 99% 88% 97% Melting fraction Ingots 0% 0% 0% Dust 7% 0% 2% Dust 29% 10% 15% Slag 6% 1% 2% Slag 90% 71% 85% Slide title pt CS and SS, 5200 tonne LWRs, cont. Co-60, container scrap Cs-137, container scrap

Text 24 pt Bullets level 2 20 pt

Blasting residues Ingots Dust (melting) Slag (melting) Blasting residues Ingots Dust (melting) Slag (melting) Co-60, large components Cs-137, large components

Pre melting Ingots Dust (melting) Slag (melting) Pre melting Ingots Dust (melting) Slag (melting) Slide title pt CS and SS, 5200 tonne LWRs, cont.

Text For the metal recycling process 24 pt Bullets level 2 • Co-60 20 pt – Melting in combination with blasting and pre melting actions is effective. • Cs-137 – Melting is the outstanding most effective individual step, and can be used in combination with blasting and pre melting actions Slide title pt Material differences, metals recycling

Text • Al 24 pt Bullets level 2 – Total amount melted 800 tonne 20 pt – Nuclide distribution • Co-60 dominating with >60% • Top six corresponds to 95% Slide title pt Material differences, metals recycling

Text • Lead 24 pt Bullets level 2 – Total amount melted 400 tonne 20 pt – All ingots free released – Nuclide distribution • Sr-90 dominating with >50% • Top six corresponds to 89% • More ingots needed to sort out normal vs. unusual cases Slide title pt Literature comparison

Text 1. NCRP (2002). Managing Potentially Radioactive Scrap Metal, 24 pt NCRP Report No 141, NCRP, Bethesda, MD. Bullets level 2 20 pt • Table 6.2, Applicable for steel • Large uncertainty for some nuclides (combined information from different sources) 2. QUADE, U. and MÜLLER, W. (2005). Recycling of radioactively contaminated scrap from the nuclear cycle and spin-off for other application, Rev. Metal. Madrid Vol. Extr. (2005) 23-28. • Table 1, Applicable for steel • Detailed nuclide distribution for many nuclides Slide title pt Literature comparison, CS and SS

Nuclide Ref. Note Steel Slag(%) Dust Other (%) Text (%) (%) 24 pt Co-60 [1] 20-100 0-1 0-80 0 Bullets level 2 20 pt [2] 88 11 1 0 Container Min - Max 29-92 2-14 6-58 0 Container Median* 70 4 26 0 LC Min – Max 88-99 1-6 0-7 0 LC Median* 96 2 2 0 Cs-137 [1] 0 0-5 95-100 0 [2] <1 60 40 0 Container Min - Max 0-0 30-77 23-70 0 Container Median* 0 47 53 0 LC Min - Max 0-0 71-90 10-29 0 LC Median* 0 85 15 0 *) Median value re-scaled to 100% total sum Slide title pt Conclusions

Text • Carbon and stainless steel 24 pt – Co-60 Bullets level 2 20 pt • Totally dominating measured nuclide in the ingots (>95%) • Confirmed literature data regarding relationship between ingots, slag, and, dust • Aluminium – Co-60 dominating with >60% • Lead – All ingots free released Slide title pt Conclusions, cont.

Text • Investigated the real nuclide distribution in ingots melted 24 pt Bullets level 2 at Studsvik and its secondary waste 20 pt • Obtained a good characterization of the inventory • Supported the free release process of the ingots • Created less conservative and more precise nuclide vectors including the secondary waste • Able to give better guidelines to decommissioning projects and dismantling work • Important step in order to develop improved models for the nuclide distribution during the melting process • Supporting both waste generators and disposal organizations in their optimization work Slide title pt

Text 24 pt Bullets level 2 20 pt