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Feasibility Study on Pyroprocessing ofSpent Nuclear Fuels for Nuclear PowerPlantsT. H. Woo aa Department of Nuclear Engineering , Seoul National University ,Seoul, Republic of KoreaPublished online: 08 Jun 2011.

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Energy Sources, Part A, 33:1493–1503, 2011

Copyright © Taylor & Francis Group, LLC

ISSN: 1556-7036 print/1556-7230 online

DOI: 10.1080/15567030903397917

Feasibility Study on Pyroprocessing of Spent

Nuclear Fuels for Nuclear Power Plants

T. H. WOO1

1Department of Nuclear Engineering, Seoul National University, Seoul,

Republic of Korea

Abstract For the nuclear non-proliferation strategy as well as the energy production

in the spent nuclear fuels, it is proposed to justify the analysis of the Pu/U non-separation characteristics in pyroprocessing. The model of the pyroprocessing devel-

opment in Korea for nuclear proliferation is constructed successfully. Pyroprocessingis a promising option following the Global Nuclear Energy Partnership as well as the

Non-nuclear Proliferation Treaty. In spite of the skeptical review about the GlobalNuclear Energy Partnership, it is reasonable for Korea to develop pyroprocessing

technology, due to the request for high-level waste repository and the strong necessityof the stable nuclear fuel supply. The possibility of license should be considered,

which is the earlier stage comparing to economics, safety, environmental aspect,plant technology, and social acceptance. The volume reduction of spent nuclear fuels

is another issue due to the time limitation of the site storage by the year 2016.Recycling of a sodium fast reactor is supposed to develop with pyroprocessing by the

year 2040.

Keywords Global Nuclear Energy Partnership, Non-nuclear Proliferation Treaty,spent nuclear fuels

1. Introduction

The spent nuclear fuel treatment is the most important fuel cycle in nuclear power

generation. For the most part, the spent products are stored in the nuclear power plant

site or at an interim storage area. For the electricity production in the industry, the need

of the back-end fuel cycle usage is increasing significantly. However, there is a non-

proliferation aspect in the civilian nuclear energy industry. So, it is necessary to develop

the technology to meet the demand of the energy production as well as the nuclear non-

proliferation viewpoint (INL, 2006). The pyroprocessing technology has been developed

for the above purpose. This study aims to examine the status of current technology and

to find out the successful pyroprocessing method in Korea.

The meaning of pyroprocessing is that the conventional plutonium selective separa-

tion is blocked, which is used in the reprocessing; so there is no way to separate any

nuclear fuel without the uranium using an artificial method like the electro-chemical char-

acteristics. Namely, there is the ‘Proliferation resistance,’ which is an opposite meaning

of the reprocessing for recovering plutonium from the uranium–metal fuel of plutonium-

production reactors (Kang and Hippel, 2005). In addition, there are nearly no dangerous

Address correspondence to Dr. Taeho Woo, Department of Nuclear Engineering, SeoulNational University, Gwanak 599, Gwanak-ro, Gwanak-gu, Seoul, 151-742, Republic of Korea.E-mail: thw@snu.ac.kr

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characteristics, because the obtained nuclear fuel is used in the fast reactor and the nuclear

material is changed to be stable (Hannum et al., 1997). The liquid salt solution waste is

reused and circulated in the original processing without removing, which is impossible

in the conventional reprocessing technology. The main principle of pyroprocessing is the

electrical treatment of the spent fuel for the liquid salt solution. Section 2 describes the

methods of the pyroprocessing. Section 3 explains the technological aspect. Section 4

discusses the international cooperation. Section 5 shows the social-political strategy. And

finally, section 6 lists the conclusions.

2. Method

The modeling of the pyroprocessing is done as the Global Nuclear Energy Partnership

(GNEP), which was initiated by the United States government. As seen in Figure 1,

the Nuclear Regulatory Commission (NRC) designed the plot of the GNEP. This means

that the economical, political, environmental, and governmental aspects are combined.

The technical aspect shows the specification and pyrochemical separation. For the social-

political aspect, the process decision is a main issue. These are seen in Figure 2 for the

research need of the pyroprocessing. Therefore, the study is done as the technological

investigation as well as the social-political analysis.

3. Technological Aspect

The technological aspects are done as several physical and chemical experiments. In

Figure 3, the Gibbs free energy shows that the change of liquid cathode is smaller than that

of the solid cathode. So, the liquid cathode can prohibit the plutonium separation for the

spent fuel. Figure 3 shows that the difference is 2.14% in liquid cathode compared to the

11.11% for the Gibbs free energy change (Sakamura et al., 1998). In the electric potential

change of Figure 4, the difference is 1.48% in the liquid cathode and 17.65% in the solid

cathode (Sakamura et al., 1998). In these two analyses, the electric potential change shows

the better difference of change, which is shown as the proportional factor in Figure 5

Figure 1. Political implementations (color figure available online).

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Pyroprocessing of Spent Nuclear Fuels 1495

(a)

(b)

(c)

Figure 2. Research needs (color figure available online).

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Figure 3. Gibbs free energy change (2.14% difference between U and Pu in liquid cathode, 11.11%

difference between U and Pu in solid cathode) (color figure available online).

(Sakamura et al., 1998). This separation is shown as five test sets in Figure 6 (KAERI,

2006). The separation factor means an equilibrium ratio for the equilibration of the im-

miscible phase. The ratio of the distribution ratios of two extractable solutes is measured

under the same condition. Number 1 of the test sets has the biggest difference. As the ura-

nium distribution coefficient increases, the plutonium coefficient increases. As the liquid

cadmium cathode (LLC) voltage increases, the separation from the uranium is increased.

In Figure 7, there is the solubility in cadmium and bismuth. The lowest value is shown

as atomic number 52 (KAERI, 2006). The solid cadmium cathode has 11% difference.

Figure 4. Electric potential change (1.48% difference between U and Pu in liquid cathode, 17.65%

difference between U and Pu in solid cathode) (color figure available online).

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Pyroprocessing of Spent Nuclear Fuels 1497

Figure 5. Proportional factors (10.78% difference between liquid and solid cathodes in Energy,

19.61% difference between liquid and solid cathodes in Potential) (color figure available online).

There are several radiation measurements in pyroprocessing comparing to an example

material. The gamma radiation is higher in pyroprocessing. This is higher than that of

the plutonium-uranium extraction, which is a method of the nuclear reprocessing. This is

also tested in Figure 8 as the spontaneous neutron as well as the gamma dose (Hannum

et al., 1997). It is better in the case of the spontaneous neutron for the pyroprocessing.

Thus, the proliferation resistance can be obtained in Figure 9 (Hannum et al., 1997). This

means that the radiation detection of the neutron and gamma radiation is a method of the

proliferation resistance, because the easier detection can block someone from producing

the plutonium for the purpose of nuclear arms construction.

4. International Cooperation

How to develop the back-end nuclear fuel cycle in Korea, which is incorporated with the

GNEP in the United States, has been investigated. The main reasons for the development

are to recycle the high level nuclear waste and to reduce the quantity of the spent

nuclear fuels (SNFs) (U.S. DOE, 2002). This meets the economical demand of the

electricity production and the environmental protection of the waste management in the

long run. It is very certain that pyroprocessing is a promising option for the Korean

nuclear society following the GNEP as well as the Non-nuclear Proliferation Treaty,

where conventional reprocessing in high-level nuclear waste treatment is prohibited.

For pyroprocessing to progress in the Korean nuclear industry, the commercialization,

industrialization, and proliferation resistance should be addressed simultaneously. Hence,

the R&D programs could be large and complicated due to the scale and fund aspects,

which will require international cooperation. Considering the situation of Japan, the

future collaboration studies with Research Institute of Atomic Reactors in Russia are

to be performed under the Japan Nuclear Cycle Development Institute-led fast reactor

and fuel cycle feasibility study. Although, the NRC in the United States announced the

skeptical review about the GNEP-related back-end fuel cycle promotions, it is reasonable

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(a)

(b)

Figure 6. Separation factor comparisons (color figure available online).

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Pyroprocessing of Spent Nuclear Fuels 1499

(a)

(b)

Figure 7. Solubility (Cd-ANL, Bi-ORNL) (color figure available online).

for Korea to develop the pyroprocesing technology, because there is no high-level waste

repository and there is a strong necessity for the treatment of the high-level nuclear waste.

5. Social-political Strategy

The aspect of the social-political approach suggests the justifications of the pyroprocess-

ing, where there are three kinds of justifications: the technical justification, the consensus

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Figure 8. Proliferation resistance values (80,000 times and 700 times higher for gamma dose and

spontaneous neutron each in pyroprocessing) (color figure available online).

justification, and the analytic justification. The technical justification is the technical

analyzed cases, such as the Gibbs free energy, weight fraction, and the solubility, which

are explained in the previous section. The consensus justification focuses on the plutonium

diversion prohibition. Finally, the analytic justification is the proliferation resistance value.

These meanings are going to the Pu/U non-separation, which eventually goes to nuclear

proliferation resistance. This is seen in Figures 10 and 11. In the political consideration,

the nuclear proliferation resistance is going to the pyroprocessing, which is used in

the sodium fast reactor (SFR) for the nuclear fuel as shown in Figure 12. On these

Figure 9. Proliferation resistance values (4 times and 20 times higher for decay heat and

spontaneous neutron each in pyroprocessing) (color figure available online).

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Pyroprocessing of Spent Nuclear Fuels 1501

Figure 10. Model of justification for nuclear proliferation resistance by Pu/U non-separation (color

figure available online).

Figure 11. Verification scheme for Pu/U non-separation (color figure available online).

Figure 12. Model of the pyroprocessing development for nuclear proliferation resistance (color

figure available online).

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1502 T. Woo

processes, several key points are combined as the recycle, international cooperation,

conference/meeting, volume reduction, training/education, and license/environment.

6. Conclusions

It is necessary for the basic points to be the technical viability and operability in order to

make a decision of the possibility of pyroprocessing in the nuclear fuel cycles (Heising,

1980). All stages of the development should be connected. It is usually considered that

the good ways from fundamental studies go to further development in demonstration

experiments, and these might go to the development and implementation. The processes,

however, are useless due to the cost, ideas, and data. Therefore, for better project

management, it is necessary to make the progress schedule properly. After the program

of the process is formalized, research should be done for the industrialization. The result

of the engineering scale research can be applied to the process in the industrial scale

economically. There are some other matters in the legal licensing and social demand

which could be done by the industrial aspect. The possibility of licensing should be

considered in the level of concept development, which is the earlier stage compared to the

economics, safety, environmental aspect, plant technology, and social acceptance. Many

aspects of the elements are interlinked and dependent upon each other. So, therefore, the

linage and dependency will ensure the prior object, the obstacle issue, and the useless

factor. The following are the conclusions of this study in respect to the Korean nuclear

industry:

� The Korean nuclear industry can improve the technology and data of pyroprocess-

ing by cooperating with other countries.

� International promotion should be continued systematically and periodically.

� The conference and meetings should be held in a timely manner.

� The proposed training committee discusses the educational program of the engi-

neers in the pyroprocessing projects.

� The proliferation resistance nuclear fuel processing is constructed.

In this study, for pyroprocessing development, more considerations have been investi-

gated for commercialization. For the milestone of the business in Korea, the repository

construction of SNFs is proposed until 2016, due to the time limitation of the site volume

capacity. The SFR is supposed to develop with pyroprocessing around 2040. It expected

that for commercialization as well as the R&D business to be successful, the discussed

points need to be accomplished.

Acknowledgments

The author wishes to thank Dr. E. H. Kim from the Korea Atomic Energy Research

Institute (KAERI) and Dr. H. J. Park from the Korea Science and Engineering Foundation

(KOSEF) for their research discussions.

References

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