1. Introduction

In nuclear power plants employing light or heavy water as a coolant as well as in most waste treatment plants, ion-exchange materials are widely used for the purification of various water streams [1]. Since the spent ion-exchange resins retain radioactive nuclides as well as chemical impurities, they present a form of low level radioactive waste (LLW) and intermediate level radioactive waste (ILW) which requires particular handling and treatment for their storage and disposal. According to [2] and [3], ion exchange resins are used at commercial NPPs to capture radioactive contaminants dissolved in water during plant operations. After some time, the capability of ion-exchange resins to eliminate the contaminants from the water reduces and it must be removed to replace with new ion-exchange resins. In many cases in the nuclear industry, spent ion-exchange resins (spent resins) are considered as a problematic solid waste and require special treatment and precautions to meet the waste acceptance criteria for a disposal site.

Spent resins are a form of low and intermediate level radioactive waste that must be treated and conditioned for storage and disposal purposes. The methods used for conditioning and treatment can achieve several targets regarding management of spent resins, and the improvement of safety and economics linked with the further handling, storing and disposal are taken into account. Managing the spent resins that are generated from an NPP involves treatment of spent resins prior to the conditioning and may reduce the volume of waste. Therefore, the objectives for spent resins radioactive waste management are defined as shown in Fig. 1. The objectives are based on IAEA Technical document for Management of Spent Ion-Exchange Resins from Nuclear Power Plants [1].

The top-level objective, which is the management of spent resins, has five primary objectives. There are shown as volume reduction, immobilization, storage, disposal, and economic. The volume reduction objective requires pre-treatment method options, which are dewatering, drying, and blending and concentration averaging. Dewater and drying treatment is a traditional method that mainly used for conditioning of spent ion-exchange resins. Then, they are packed with or without absorbents into containers for storage or even for disposal [1]. The method generally preferred at present is to include immobilization in the conditioning. The blending and/or concentration averaging objective has two sub-objectives of reducing the amount of waste stored and lower the disposal class, with potential impact in reducing worker exposure. Generally, spent resins are classified as low and high activity spent resins. Low activity spent resins will be treat prior to volume reduction. However, high activity spent resins are usually stored for a long period of time for the sufficient decay; then they are transferred to a disposable container such as a High Integrity Container (HIC) [4]. But in the blending method, it is proposed to treat both low and high activity spent resins with an appropriate method in order to assure safety during handling, storing and disposal.

Blending is defined as a process which combines materials with different radionuclide concentrations into a single tank or container to produce a mixture that is more amenable to storage, further treatment, and final disposal. Blending may include some forms of treatment and general waste packaging processes [5]. The blending method also requires adequate mixing for homogeneity of the mixture product to make sure final radionuclide concentration meets the WAC requirement for final disposal. However, blending is not a dilution process, which is mixing contaminated waste with clean or uncontaminated material solely to reduce waste classification. This process increases the total volume of contaminated waste to be managed, thus dilution is not allowed by the regulatory body. Meanwhile, blending of wastes to reduce the hazards in handling the wastes is desired and should be required [5]. After the treatment process, immobilization process is taken place to reduce the mobility of radioactive materials in the wastes and to ensure safe transport, storage, and disposal. The nature and extent of the two process steps can vary much depending on the technique applied. Thus, it is possible to combine both volume reduction and immobilization in one process as subsequent operational steps, as it is done in many bituminization methods. Cementation and polymerization are most commonly used for immobilization method of spent resins.

The Barnwell LLW disposal facility closed to states outside the Atlantic in June 2008. As a consequence, 90 of the 104 operating reactors have to store their own wastes as reported in [6]. This issue urged licensees and industry representatives exploring and considering a mixing of low level radioactive waste (LLW) as a way to mitigate the impact of Barnwell’s closure. The blending of spent resins from NPP which can be blended into a relatively uniform mixture is once initiated by a waste processor in Tennessee. This blending approach would allow some materials that would otherwise have been disposed of as Class B or C waste to be mixed with Class A waste to create a Class A mixture [6] as it can be accepted in Class A disposal facility. As reported by P. Tran (2008), Class B and C resins account for approximately 12,000 ft³ of LLW annually disposed, whereas Class A resins account for about 75,000 ft³ annually disposed [7]. The article states that if resin blending was practiced, the volume of Class A resin would increase by approximately 8,000 ft³·yr^-1 to a total of 83,000 ft³·yr-1. This would leave about 4,000 ft³ waste classification and disposal of Class B/C resin to be stored as shown in Table 1 below.

For this study, the assumption is made that there will be a reduction in the disposal cost of LLW in the Wolsong repository compared with the disposal cost of ILW. Therefore concentration averaging and blending ILW may be highly beneficial from a cost perspective. In trying to combat the issue of ILW currently stored in NPP site, blending is proposed as an alternative treatment to convert the stored ILW Waste to LLW so as to meet the specific WAC requirement at Wolsong site, and then be shipped for disposal. This study aimed to develop the management of spent resins that are generated from the nuclear power plant through the blending method. The Final Safety Analysis Report (FSAR) for Shin Kori 3&4 is selected to provide the annual amount of radioactive waste generated. Then, the concept of blending method is developed by considering the Korean situation. In addition, blending is a target to give benefits in improving the existing radioactive waste management in Korea by reducing the spent resins stored in the plant.

2. Spent Resins (SR) Waste in Korea

2.1 Status of spent resins treatment method

Since the operation of the Kori 1 NPP in 1977, KHNP has used various treatment methods for generated solid radioactive waste. In case of spent resins, there are three treatment methods available which are cement solidification, drying, and repacking. However, cement solidification and repacking into the 320 L drum are currently not used due to high leachability and has less volume reduction capacity [8]. Table 2 describes the treatment method for spent resins.

In APR1400, polymer solidification system is installed as a part of the waste treatment system. It consists of a mobile type polymer solidification system to solidify spent resins, and a stationary polymer solidification system to solidify dried R/O concentrate, as shown in Fig. 2 [4].

The polymer solidification method has been used over 40 years in the US, Japan, and Europe due to many advantages on compressive strength, durability, chemical resistance and water tightness. This method was chosen for the APR1400 by KHNP to treat generated waste which is homogenous such as concentrate, spent resin and sludge to be acceptable for disposal into the repository. Polymer, which is used to solidify in Shin-Kori 3 & 4, is supplied by AHAE Corporation in Korea and it is composed with 2 types of Radson 100 and Radson 200 as described in Table 3 [8].

2.2 Estimated spent resins inventory for Shin- Kori 3 & 4

The inventory of spent resins should be known before blending process takes place. It is the crucial part to be considered to perform blending. Therefore, the inventory such as volume or mass (as applicable), and radionuclides activity of spent resins are used to determine the activity concentration of the waste. In general, waste volumes may be calculated from the mass of the waste divided by a representative density. According to [9], for spent resins, the volume and mass of the waste are the dewatered volume and mass. Spent resins in APR 1400 generated from purification system of Chemical and Volume Control System (CVCS) and Spent Fuel Pool (SFP) system contains high activity and are classified as ILW, while low activity spent resin generated from Liquid Radioactive Waste System (LRS), Steam Generator Blowdown System (SGBDS), and Spent Fuel Pool and Cleanup System (SFPCCS) are classified as LLW. Table 4 shows estimated of spent resins inventory of Shin Kori unit 3&4 based on the FSAR estimation. From this report, the estimated volume of spent resins generated per year is approximately 71.36 m³maximum for both units [10].

The total volume of 71.36 m³·yr-1 is estimated after dewatering and solidification treatment by polymeric solidifying agents to fill the void of spent resins. The spent resins may contain significant quantities of radionuclides, which include corrosion, fission and activation products [11], [12]. The major radionuclides that may be present include ¹³³Ba, ¹³⁷Cs, ⁵⁸Co, ⁶⁰Co, ⁵⁵Fe, ⁵⁴Mn, ⁶³Ni, ⁹⁹Tc, and ⁶⁵Zn [2]. Therefore, the activities of major radionuclides were generated from the FSAR Shin-Kori 3&4 as shown in Table 5.

3. Methodology

3.1 General operational concept of blending

Remarkable amounts of spent resins are generated from the NPP operation and it is categorized as solid radioactive waste. Based on their classification, spent ion-exchange resins can be either low level waste or intermediate level waste. To reduce the amount of spent resins stored and lower the waste disposal class, blending method is applied. By this blending method, the final mixture of blendable spent resins is allowed to dispose in the LLW Disposal Facility if it meets with the WAC requirements and blending operational concept explain as in Fig. 3.

In Korea, a LLW disposal facility known as the nearsurface disposal facility is the second phase of construction of the repository facility. The capacity of this facility is 125,000 drums in the area of 120,000 m², as shown in Fig. 4 [13]. There are 20 numbers of vaults, with the size of 20 × 20 × 9.55 m, and width of 0.6 m.

3.2 Requirement Analysis

Requirements are the keystone that needs to be considered to propose and implement a new process or technology. According to Buede, stakeholder’s requirements provide operational statements by the stakeholders concerning to their needs [14]. In Korea, the stakeholders that relate to the radioactive waste management are a regulatory body (KINS), Disposal Facility (KORAD), and NPP owner (KHNP). Table 6 describes the requirement analysis for spent resins management by blending method.

3.3 Screening process of blending application

Spent resin is categorized as the single waste type with multiple waste streams. In the NPP, there are two waste streams of spent resins with different radiological characteristics; which are one from the primary system, and the other one from the secondary system are combined in a single container. Generally, ion exchange resins from primary system are high activity resin and classified as ILW, meanwhile, ion exchange resins from the secondary system are low activity resin and classified as LLW [15]. In order to classify a mixture of multiple blendable waste streams, screening criteria may be used to simplify blending application, as shown in Fig. 5. In this study, low level and intermediate low level waste of spent resins are to be blended. Thus, the other radioactive solid wastes such as dry active waste and spent filters will be screened out and waste characterization is done to know either waste are blendable waste streams or discrete items. This process includes identifying the radiological and physical characteristics of the waste.

Next, the determination of blending properties takes place. If waste can be physically mixed to create a homogenous final product or do not expect to contain durable items with significant activity, then the waste can be considered further for blending. If not, unblendable waste cannot perform blending and screened out. The last step of the screening process is the possibility and applicability for blending. It means that after blending, it is expected to give effects of:

3.4 Blending method options description

Mixing or blending of particles is an important process in many industries, such as chemical, ceramic, plastic, and minerals [16]. The main objective of mixing is to achieve a highly homogenized final product of mixture. In a normal scenario, spent resins are segregated by their activity levels in holding tanks by spent resin transfer and storage subsystem. It is designed to transfer the expended radioactive resins from their vessels to the spent resin tanks where the resin is held up prior to being processed [17]. In this study, the LLW and ILW spent resins would be pumped from holding tanks which are High and Low activity storage tanks into the 200 L drum in the proper proportions such that final mixture would meet LLW disposal concentration limits. The LLW and ILW spent resin would be blended together in a mechanical mixing process to create a final homogeneous mixture and then dewatered or dried. After that, the blended waste would then be placed in shielded shipping casks, as appropriate, and transported to a disposal facility. Blending provides a disposal pathway for ILW concentration spent resins. There are two options of blending method can be performed, either in-drum mixing or an external mixing process. The 200 L in-drum mixing process does not require blending tank and illustrated in Fig. 6.

On the other hand, external mixing process requires a blending tank as shown in Fig. 7. Continuous in-line mixers which allow small hold up and easy cleaning, as well as batch mixers of various types, can be used for blending spent resin wastes all together prior to leading the storage drum. This process also called as an external mixing process of blending. From both option processes, there is no change in chemical structure and volume of spent resins since the operations conducted without artificial heating or cooling.

3.5 Performance requirements

In order to satisfy the performance requirements of the blending process, two main parameters are measured: (i) radionuclide concentrations that meet WAC limits, and (ii) blending mixing ratio between high and low activity spent resins for homogeneity. Blending waste must meet the limits on radiation exposures at the disposal facility and limits on how much the radioactive concentration may vary [18]. The objective for the blending operation is to determine the optimal amount of spent resins required for adequate mixing to meet the WAC of the disposal facility. Table 7 shows the limits of radionuclides concentration for disposal as mentioned in NSCC Notice No. 2014-003.

According to [9], some cases of multiple blendable waste streams of the same waste type, for example, primary and secondary spent resins may be combined in the same container without blending. If the WAC limits in Table 7 are not exceeded, there is no need for the waste to be blended and the radionuclide concentration can be averaged over the volume of the waste or container. In this study, it is necessary to determine the radionuclide concentration based on volume in different waste streams. To blend the spent resins, mass balance approach is determined as the best approach to be used and the blending materials are described in Eq. (1) below.

Where

WAC of RN concentration = Disposal Facility WAC for radionuclides limit (Bq·g^-1)

High activity SR concentration = Radionuclides concentration averaged over the volume in the waste stream (Bq·g^-1)

Low activity SR concentration = Radionuclides concentration averaged over the volume in the waste stream (Bq·g^-1)

From Table 8, the values of ⁶⁰Co and ¹³⁷Cs concentrations from FSAR were compared with the WAC concentration limits stipulated by NSSC Notice No. 2014-003. The calculation shows that only ¹³⁷Cs concentration is above the WAC limits. Therefore, the ¹³⁷Cs was used to calculate mixing ratios of ILW and LLW spent resins in order to meet the WAC limit for safe disposal of spent resins blendable waste.

Creating a homogeneous mixture is often the ideal situation when performing waste treatment or stabilization [5]. Regulatory guidance as provided by NRC stated that blended waste must ensure safe disposal which includes uniformity or how well-mixed the waste must be [18]. To achieve homogeneity of the mixture, the optimal mixing ratio should be determined and sufficient enough to satisfy the performance requirements of the disposal facility. The calculation of blending ratio is based on FSAR for Shin- Kori 3&4:

From the concentration limits given in the NSSC Notice No. 2014-003, dominant radionuclides ¹³⁷Cs and ⁶⁰Co are used in this study and considered for the following calculation. The optimal mixing ratio between low and high activity spent resins concentration for can be calculated as shown in Eq. (2). Summary results of blending process are then tabulated in Table 9.

where,

4. Results and Discussion

The HIC is used to package dewatered and dried spent resin [17] and is currently being stored in HIC in the NPP sites for more than 20 years. Basically, spent resins are dewatered and stored in-drum with 10 cm concrete liner. The old practice done by KHNP used cementation for waste immobilization, but leakage problem raised due to internal corrosion caused by free-standing water at the bottom. Thus, repackaging of the wastes become necessary and will result in additional occupational exposure [21]. A drying process is also applied to treat spent resin, which completely dried and filled in HIC container. Unfortunately, HIC is deemed not fit for acceptance at the Wolsong Disposal Site. HIC is expensive and stored spent resin requires constant monitoring of free-standing water. According to US NRC, the HIC is not acceptable for disposal unless special provisions have been arranged with disposal repository site [22]. The US NRC also not approved any HIC fabricated solely of HDPE, although the US NRC has approved HICs with major components fabricated from HDPE [21].

Currently, there is no WAC for ILW, so it must be kept in on-site interim storage. Even if the WAC for ILW is established, the disposal cost for ILW is expected to be higher than LLW. Therefore, blending contributes to solving the ILW disposal problems and it is suitable as a way to minimize ILW. On the other hand, the blending method can also be a waste management strategy in reducing interim storage of LLW, with optimization of life cycle cost. All blendable wastes produced from the blending process are intended for final disposal. There is no increase in disposal volume since blending is a mixing between different levels of contaminated materials in appropriate portion. As safety is always a priority, blending results in no decreasing in health and safety issues such as occupational safety and exposure.

4.1 Effects of Blending Method

From blending method application, it is obvious that amount of spent resins stored is reduced and also give effects in lowering a disposal class. Table 10 and Fig. 8 summarized the findings from this study.

Fig. 9 focuses on activity distribution of spent resins before and after the blending process. It is shown that after the blending process, there is a significant reduction of high level SR. It is calculated that approximate 44.3% of ILW spent resins blended together with LLW spent resins, which almost near to half of ILW can be disposed in LLW repository after applying the blending method.

4.2 Waste Management Cost

The optimal treatment and disposal option needs to be chosen wisely based on research and international experiences. To manage spent resins, there are two options considered:

Efforts to minimize ILW by blending ILW high activity spent resin with LLW low activity spent resin will contribute to minimizing disposal costs [2]. In Korea, the LILW management cost is regulated by MOTIE Notice No. 2015- 132 “Regulation on the estimation of management cost of radioactive waste and management share of spent fuel” [23]. The LILW disposal cost, which is required for store and disposal after waste acceptance from KHNP, is charged $11,031.67 per unit drum (200 L) by repository operator KORAD according to MOTIE Notice No. 2015-132. Meanwhile, HIC disposal cost is applied as $ 77,883.62 per unit HIC, which driven from disposal cost in MOTIE Notice. In this study, economic evaluation considering treatment cost and disposal cost is performed and projected from data in [4]. To find the final economic feasibility, both treatment and disposal cost were compared of each option. According to [4], the transportation cost to the low and medium radioactive waste disposal area is excluded because the selected spot for the waste drum storage is not yet decided. The assumptions for both options are listed as below:

According to [4], Shin-Kori 3&4 (APR1400) are operating units and the expected generation rate of spent resins is 33 drums per year, which is 6,600 L per year in volume. The estimation is made by considering the power output of the plant and application of Polymer Solidification System (PSS) to process low activity spent resins. By using the data above, the estimated disposal cost per year for each option was calculated and shown in Table 11.

The economic evaluation result for polymerization is done by [4]. In their research, it is assumed that the process time for spent resins is 580 hours, operation time per year is 176 hours, and 40 years of polymerization operation time. As a basic input data, inflation rate of 1.03% [4] and currency conversion of $1 equals to ₩1,105 were used. The other parameters such as facility cost, material cost, manpower, personnel expenses, and electricity are also factored in. Therefore, the total polymerization treatment cost for 40 years is estimated as $9,567,000. Since both options applied polymerization process, it can be assumed that cost of polymerization will be same to dispose 33 unit drums per year. In option 2, blending process is applied before polymerization. By considering the assumptions as listed above, the total waste management cost in 40 years operation time for both options is tabulated in Table 12.

It can be seen from the above Table 11 and 12, the estimated waste management cost for Option 2 with blending application is approximately 10% smaller than Option 1 with the current PSS in APR1400. This is caused by the reduction of disposal cost resulting from the blending of spent resins before the polymerization process. Other than that, blending approach also gives several advantages. These include a significant reduction of ILW spent resins by approximately 44.3% and it can be considered as an alternative treatment for high activity spent resin to be safely disposed in the LLW disposal facility if satisfied WAC requirement. Blending attends the issues such as the required continuous monitoring of free-standing water in HIC.

4.3 Considerations

To implement blending method, several considerations are needed to be taken into account and discussed as follows.

4.3.1 National policy

The proposed blending method is suitable for batch scale processing. Regarding the current national policy of radioactive waste management, dilution of radioactive waste is not allowed to be performed. According to [5], “Blending of radioactive wastes should not only be formally recognized as an acceptable practice, it should be encouraged as a legitimate and practical solution to promote efficient use of available disposal capacity and to reduce risks of handling the waste by workers.” Therefore, it is suggested that a national policy may need to be revised in order to allow the blending application in radioactive waste management in the future. Moreover, this approach must be supported by a rational discussion between related stakeholders, authorities and the public to gain acceptance. Public participation is vital because without it a sound policy development for blending would not be possible.

4.3.2 Waste package for final disposal

Wastes must be remains in a stable form and placed in the container as a final waste package. After blending process, the blendable spent resins are further treated by polymerization in the same 200 L disposable steel drum. The final mixture of blendable spent resins is classified as LLW, thus vault type of repository for LLW is recommended and the WAC requirement of repository site is fulfilled. This recommendation is supported by reference [24], which stated disposal of spent resins in a conditioned form may be possible for the low-level category in engineered structures. Other than that, a facility needs to consider and prepare a disposal of high-activity waste in terms of dose limits. In this case, it is important to do a performance measure by checking the dose rate of the waste package after applying blending method. Then, it is verified by measuring the external dose rate of the final waste form to be shipped if the waste package is compliance with the WAC requirement. However, implication of blended spent resin disposal in a LLW facility to the licensed total and nuclide specific inventory limits of the Wolsong disposal facility also needs to be considered.

4.3.3 Long-term stability prior to disposal

Long-term stability of the waste form is generally required for both storage and disposal. According to [25], with the evolution of performance-based disposal facility acceptance criteria, it is now required that spent ion exchange materials meet specific quality requirements prior to disposal. This is the reason why WAC is important in order to clarify the quality of waste forms for final disposal and appropriate treatment options. Therefore, the immobilization concept then being a general practice to stabilized spent resins only after a short period of interim storage. The conditioning technologies are essential for the immobilization of radioactive solid waste and forming the initial engineered barrier required for their transportation, storage, and disposal [26]. In this study, it is proposed to apply blending method then followed by polymerization as a waste stabilization. However, this approach of a conditioning process will depend on the requirements for the Wolsong disposal site and supported by the national policy. Obtaining a freestanding final product after waste conditioning is a basic criterion [24] and always considered. As reported in NRC Final Report on 2013 [2]:

“It is an NRC regulatory requirement in 10 CFR 61.56 (b) (2) that waste must be converted into a form that contains as little free standing and noncorrosive liquid as is reasonably achievable, but in no case shall the liquid exceed 1 percent of the volume of the waste when the waste is in a disposal container designed to ensure stability or 0.5 percent of the volume of the waste for waste processed to a stable form.” [2:4-1]

In general, most of the disposal facilities define acceptable levels of free liquids and requirements for waste form stability as part of WAC requirement. These waste acceptance criteria will determine if spent ion exchange materials must be dewatered, stabilized or treated in some other manner prior to disposal [25]. The water content of the resins was calculated according to ASTM Standard Test Method D2187-77, “Physical and Chemical Properties of Ion Exchange Resins,” [27]. According to this document, water content can be calculated as in Eq. (3):

Where,

4.3.4 Performance assessment at disposal site

Protection to the public, intruder, and environment is a crucial part that needs more concern to dispose blendable waste in repository site. Generally, ILW requires packaging and shielding to protect workers handling the waste and must also meet physical stability requirements. In addition, disposal facilities must also meet special requirements to protect against an inadvertent human intruder after site closure and after institutional controls have lapsed [28]. Performance of the blended wastes in the disposal facility must be determined by performance assessment to meet the performance objectives of repository site. Moreover, methods used for demonstrating compliance with the homogenization requirements that are derived from the performance assessment for specific low level wastes can be documented in the generator’s waste certification program [5].

The blending process is suggested by the US NRC to be risk-informed and performance-based. Referring to [29], a final blended waste form could be safely disposed by clarifying several considerations need regarding the blending method, such as:

According to [6], protection of an inadvertent intruder is one of the four performance objectives for a LLW disposal facility as stated in 10 CFR Part 61, “Licensing Requirements for Land Disposal of Radioactive Waste.” This special requirement made to prevent an intruder from receiving an unsafe exposure to radioactivity. The Concentration Averaging-Branch Technical Position in their document also mentioned that site-specific concentration averaging approaches may be proposed by disposal facility licensee. Therefore, information provided to the regulatory authority should include [9]:

4.3.5 Health and safety requirement

The operational safety and exposure is a part of health and safety requirement that need to be considered in applying blending method for spent resins management. It is more efficient to combine these wastes into one or several tanks in such a facility, rather than keep them separate after they are removed from service [29]. Since the doses from a mixture of waste streams with different radiation levels may result in lowering radiation levels of combined mixture, blending might be performed to keep radiation exposures to workers as low as reasonably achievable. A guiding principle that has been proposed is that waste management practices should always consider waste blending at all stages of waste management to reduce the hazards of handling the waste during treatment, storage, and characterization or preparation for final disposal. The objective of this principle is to promote blending as a cost-effective method for disposing higher activity wastes within available disposal facilities in a way that will reduce risks of handling the wastes [5]. In addition, combining high-activity wastes with a large volume low activity wastes prior to disposal as applied in blending method will reduce concentrations and result in a more uniform distribution within the disposal facility.

5. Conclusion

In many cases in the nuclear industry, spent ion-exchange resins are considered as a problematic solid waste and it requires a special treatment and precautions to meet the waste acceptance criteria for the disposal site. A new treatment method was proposed for the improvement of the solid radioactive waste management system which focused on spent resins in the APR1400 based on feasibility, performance, and economic studies. The proposed treatment method is a suitable method for ILW minimization and in-turn reduced disposal cost. The blending of ILW was selected as an option for the current system since it will enable the NPP operators to safely dispose ILW exceeding the Wolsong WAC.

In this paper, the management of spent resins was studied and proposed with respect to the blending treatment method, the feasibility of blending, and economic study for spent resins management cost. Application of the blending method has the potential to (i) reduce the amount of spent resins stored on-site, (ii) lower disposal class, and (iii) minimize workers exposure. These advantages of blending might result in cost saving for spent resins waste management, as it can give a reduction in disposal cost. The blending approach proved that there will be a reduction in the disposal cost in the Wolsong repository site. Thus, concentration averaging and blending may be highly beneficial from waste class and disposal cost reduction perspective. Through all the considerations as discussed in the previous chapter, the planning to manage the spent ion-exchange resins waste generated from the NPPs in Korea by blending method approach could be implemented in future.