Studies of thermonuclear neutron usage means for radioactive waste transmutation

Studies of thermonuclear neutron usage means for radioactive waste transmutation

Two variants of radwastes transmutation schemes using thermonuclear neutrons are considered. In the first case transuranium elements and fission products are not separated while in the second case these are irradiated separately. Advantages and drawbacks of both cases were analyzed. Simulation of ra...

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Veröffentlicht in:Вопросы атомной науки и техники
Datum:2008
Hauptverfasser: Rudychev, Y.V., Slabospitskiy, R.P., Khazhmuradov, M.A.
Format: Artikel
Sprache:English
Veröffentlicht: Національний науковий центр «Харківський фізико-технічний інститут» НАН України 2008
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Iter and fusion reactor aspects
ITER and fusion reactor aspects
Online Zugang:https://nasplib.isofts.kiev.ua/handle/123456789/110798
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Zitieren:Studies of thermonuclear neutron usage means for radioactive waste transmutation / Y.V. Rudychev, R.P. Slabospitskiy, M.A. Khazhmuradov // Вопросы атомной науки и техники. — 2008. — № 6. — С. 67-69. — Бібліогр.: 5 назв. — англ.

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Digital Library of Periodicals of National Academy of Sciences of Ukraine
id nasplib_isofts_kiev_ua-123456789-110798
record_format dspace
spelling Rudychev, Y.V.
Slabospitskiy, R.P.
Khazhmuradov, M.A.
2017-01-06T13:02:48Z
2017-01-06T13:02:48Z
2008
Studies of thermonuclear neutron usage means for radioactive waste transmutation / Y.V. Rudychev, R.P. Slabospitskiy, M.A. Khazhmuradov // Вопросы атомной науки и техники. — 2008. — № 6. — С. 67-69. — Бібліогр.: 5 назв. — англ.
1562-6016
PACS: 07.05.Dz
https://nasplib.isofts.kiev.ua/handle/123456789/110798
Two variants of radwastes transmutation schemes using thermonuclear neutrons are considered. In the first case transuranium elements and fission products are not separated while in the second case these are irradiated separately. Advantages and drawbacks of both cases were analyzed. Simulation of radwastes transmutation systems was performed. Analysis of radwastes transmutation efficiency for all cases was carried out. Physical backgrounds for radwaste transmutation by thermonuclear neutrons were prepared.
Рассматривается два варианта системы трансмутации радиоактивных отходов (РАО) с помощью термоядерных нейтронов. В одном – трансурановые элементы и продукты деления не отделены друг от друга, в другом варианте – облучаются раздельно. Проанализированы преимущества и недостатки каждого из вариантов. Выполнено моделирование систем трансмутации РАО. Проанализирована эффективность трансмутации РАО для каждого из вариантов. Подготовлено физическое обоснование для трансмутации РАО термоядерными нейтронами.
Розглядається два варіанти системи трансмутації радіоактивних відходів (РАВ) за допомогою термоядерних нейтронів. В одному – трансуранові елементи і продукти ділення не відокремлені один від одного, в іншому варіанті – опромінюються роздільно. Проаналізовано переваги і недоліки кожного з варіантів. Виконано моделювання систем трансмутації РАВ. Проаналізовано ефективність трансмутації РАВ для кожного з варіантів. Підготовлено фізичне обґрунтування для трансмутації РАО термоядерними нейтронами.
en
Національний науковий центр «Харківський фізико-технічний інститут» НАН України
Вопросы атомной науки и техники
Iter and fusion reactor aspects
ITER and fusion reactor aspects
Studies of thermonuclear neutron usage means for radioactive waste transmutation
Дослідження можливості використання термоядерних нейтронів для трансмутації РАВ
Исследование возможности использования термоядерных нейтронов для трансмутации РАО
Article
published earlier
institution Digital Library of Periodicals of National Academy of Sciences of Ukraine
collection DSpace DC
title Studies of thermonuclear neutron usage means for radioactive waste transmutation
spellingShingle Studies of thermonuclear neutron usage means for radioactive waste transmutation
Rudychev, Y.V.
Slabospitskiy, R.P.
Khazhmuradov, M.A.
Iter and fusion reactor aspects
ITER and fusion reactor aspects
title_short Studies of thermonuclear neutron usage means for radioactive waste transmutation
title_full Studies of thermonuclear neutron usage means for radioactive waste transmutation
title_fullStr Studies of thermonuclear neutron usage means for radioactive waste transmutation
title_full_unstemmed Studies of thermonuclear neutron usage means for radioactive waste transmutation
title_sort studies of thermonuclear neutron usage means for radioactive waste transmutation
author Rudychev, Y.V.
Slabospitskiy, R.P.
Khazhmuradov, M.A.
author_facet Rudychev, Y.V.
Slabospitskiy, R.P.
Khazhmuradov, M.A.
topic Iter and fusion reactor aspects
ITER and fusion reactor aspects
topic_facet Iter and fusion reactor aspects
ITER and fusion reactor aspects
publishDate 2008
language English
container_title Вопросы атомной науки и техники
publisher Національний науковий центр «Харківський фізико-технічний інститут» НАН України
format Article
title_alt Дослідження можливості використання термоядерних нейтронів для трансмутації РАВ
Исследование возможности использования термоядерных нейтронов для трансмутации РАО
description Two variants of radwastes transmutation schemes using thermonuclear neutrons are considered. In the first case transuranium elements and fission products are not separated while in the second case these are irradiated separately. Advantages and drawbacks of both cases were analyzed. Simulation of radwastes transmutation systems was performed. Analysis of radwastes transmutation efficiency for all cases was carried out. Physical backgrounds for radwaste transmutation by thermonuclear neutrons were prepared. Рассматривается два варианта системы трансмутации радиоактивных отходов (РАО) с помощью термоядерных нейтронов. В одном – трансурановые элементы и продукты деления не отделены друг от друга, в другом варианте – облучаются раздельно. Проанализированы преимущества и недостатки каждого из вариантов. Выполнено моделирование систем трансмутации РАО. Проанализирована эффективность трансмутации РАО для каждого из вариантов. Подготовлено физическое обоснование для трансмутации РАО термоядерными нейтронами. Розглядається два варіанти системи трансмутації радіоактивних відходів (РАВ) за допомогою термоядерних нейтронів. В одному – трансуранові елементи і продукти ділення не відокремлені один від одного, в іншому варіанті – опромінюються роздільно. Проаналізовано переваги і недоліки кожного з варіантів. Виконано моделювання систем трансмутації РАВ. Проаналізовано ефективність трансмутації РАВ для кожного з варіантів. Підготовлено фізичне обґрунтування для трансмутації РАО термоядерними нейтронами.
issn 1562-6016
url https://nasplib.isofts.kiev.ua/handle/123456789/110798
citation_txt Studies of thermonuclear neutron usage means for radioactive waste transmutation / Y.V. Rudychev, R.P. Slabospitskiy, M.A. Khazhmuradov // Вопросы атомной науки и техники. — 2008. — № 6. — С. 67-69. — Бібліогр.: 5 назв. — англ.
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fulltext STUDIES OF THERMONUCLEAR NEUTRON USAGE MEANS FOR RADIOACTIVE WASTE TRANSMUTATION Y.V. Rudychev, R.P. Slabospitskiy, M.A. Khazhmuradov National Science Center “Kharkov Institute of Physics and Technology”, Kharkov, Ukraine, e-mail: khazhm@kipt.kharkov.ua Two variants of radwastes transmutation schemes using thermonuclear neutrons are considered. In the first case transuranium elements and fission products are not separated while in the second case these are irradiated separately. Advantages and drawbacks of both cases were analyzed. Simulation of radwastes transmutation systems was performed. Analysis of radwastes transmutation efficiency for all cases was carried out. Physical backgrounds for radwaste transmutation by thermonuclear neutrons were prepared. PACS: 07.05.Dz INTRODUCTION Nowadays intensive thermonuclear neutron sources with above 1014 n/s fluxes are developed in a number of countries (France, Russia and etc.). Such neutron fluxes could be used for efficient radwastes transmutation. This is a topical problem because up to 2010 from the world nuclear reactor fleet with total power of 400 GW above 300 thousand tons of spent fuel should be removed. The problem is actual for Ukraine too. During radwastes transmutation before burial transuranium elements (TRU) and fission products (FP) with long half-decay periods (hundreds and thousands years) are to be converted into short-lived or stable isotopes. At present considerable attention is paid to a problem of radwastes transmutation [1]. In the presented paper means of thermonuclear neutron usage for radwastes transmutation were studied employing mathematical simulation methods. Two cases of transmutation systems were considered. In the first case transuranium elements and fission products are not separated and are irradiated together while in the second case these are irradiated separately. MATHEMATICAL SIMULATION RESULTS In our work we have studied transmutation of the basic transuranium elements 237Np, 241Am, and 244Cm and fission products 99Tc, 127I, 135Cs by the thermonuclear neutron beam with 1015 n/cm2 flux density. Firstly, we have used database [2] and have obtained fission (nf) and capture (nγ) cross-sections versus neutron energies of the above mentioned isotopes. Neutron energy range from 10-5 to 108 eV was considered. In the Fig. 1 an example dependencies of fission cross-section (nf) for transuranium element 241Am and capture cross-section (nγ) for fission product 99Tc are shown. For other elements cross-sections are similar but differ in magnitude. The figure reveals sharp difference in magnitude and behavior of cross-section energy dependence for neutron energies above 1 MeV [3]. While transuranium elements undergo intense fission by neutrons with En = 1...15 MeV, almost no transmutation of fission products (99Tc) occur. Neutron Energy, eV C ro ss -s ec tio n, b ar n Fig. 1. 241Am fission cross-section (σf) and 99Tc capture cross-section (σγ) versus neutron energy This peculiarities lead to two cases of transmutation systems (joined and separated irradiation). From Fig. 1 it is evident that fission products will undergo intense transmutation provided neutron energy decelerate down to En = 10…10000 eV where resonance capture occur. In this case capture probability is proportional to resonance integral ( ) ( )∫ Ε Ε − ΕΕσ=ΕΕΙ max min 1 maxmin,рез .dny Resonance integral for FP nuclei neutron capture is significantly larger than thermonuclear neutrons cross- sections. For instance for 99Tc nucleus Ires=300 barn while cross-section is about 20 barn. As a materials where non-separated TRU+FP materials to be placed we have considered lead and carbon, and for separated TRU and FP only carbon was considered. We have simulated cells with various radwastes components concentration in lead or carbon for neutrons with initial energy of 14 MeV. Cell volume averaged spectra for neutrons perform radioactive isotopes transmutation were calculated. Calculations of isotopes concentration variation in dependence of irradiation time and mode were performed. For the separated irradiation case we have determined parameters of moderator placed between cells where TRU and FP are irradiated separately in carbon matrices. Moderator consists of three layers: 1 cm beryllium, 10 cm lithium PROBLEMS OF ATOMIC SCIENCE AND TECHNOLOGY. 2008. № 6. 67 Series: Plasma Physics (14), p. 67-69. oxide and 20 cm carbon. Material with detailed description of simulation method and results were sent to “The Journal of Kharkov National University” [4] After additional calculations the most significant results could be presented as following. Firstly let us consider the case of non-separated TRU and FP are placed into two identical cells of 100 cm length and 50 cm diameter. In one cell 20% TRU (237Np – 44.5%, 241Am – 48.6%, 243Am – 6.9%) and 10% FP (99Tc – 57.7%, 135Cs – 28.9%, 129I – 13.4%) are placed into 70% lead matrix, in another cell TRU + FP with the same composition are placed into 70% carbon matrix. The cell’s bottoms are targeted by 14 MeV neutron beam 6.9 cm in diameter. Volume averaged neutron spectra are presented in the Fig. 2. From the figure it follows for carbon matrix inside energy range 1 keV…1 MeV a number of neutrons is larger than for lead matrix. This is due to higher TRU fission efficiency in carbon matrix compared to lead matrix. Neutron Energy, MeV Fl ux , n /c m 2 TRU TRU FP FP Fig. 2. Neutron spectra for (20% TRU + 10% FP + 70% C) and (20% TRU + 10% FP + 70% Pb). Spectra are averaged over cell volume Comparison of spectra from Fig. 2 with similar spectra for matrices contenting 100% lead or carbon shows neutron number resulting from (nf) reaction on TRU essentially exceeds number of initial 14 MeV neutrons (more than 9 times for lead). For transmutation calculations we have used FISPACT code [5]. It provides solution of balance equations using iteration methods and modern cross- sections databases. Concentration change in time for various isotopes, such as minor actinides and FP for different matrices and varying radwastes content were studied. In the Fig. 3 concentration changes in time are shown for 20% TRU and 10% FP placed inside 70% lead matrix. Fig. 4 presents 99Tc concentration change versus irradiation time for matrices with different carbon content. Irradiation time, days C on ce nt ra tio n, % Fig. 3. Isotope concentration versus time C on ce nt ra tio n Tc , % 99 TRU FP TRU TRU TRU TRU TRU TRU FP FP FP FP FP FP Irradiation time, days Fig. 4. 99Tc concentration change versus irradiation time for different matrices Evidently transmutation in carbon matrix (70% C) is more intense than that in lead matrix (70% Pb). Also increase of carbon concentration from 20% to 70% provides more intensive 99Tc transmutation. Concentration of 135Cs changes in a similar way while for 129I there are some differences. For 129I concentration change 70% lead matrix is same as in 70% carbon matrix. These peculiarities rely on energy dependence of (nγ) reactions for such isotopes. From Fig. 2 follows for resonance region with neutron energies En=10…10000 eV where resonance integrals for FD neutron capture are essential a number of neutrons is small. This impedes FP transmutation. We have calculated averaged neutron spectrum inside cell with FP in carbon matrix for separated TRU and FP irradiation with moderator (Be, LiO and C) placed between cells (Fig. 5). Obviously a number of neutrons in resonance region increase. One can expect this to be more suitable for FP transmutation but due to neutron absorption in moderator total number of neutrons hit FP cell in carbon decreases by about hundred of times. Hence amount of FP isotopes under transmutation will be lower than that for cell with non-separated TRU+FP. It is clear from Fig. 6 where 99Tc 68 concentration change versus time is shown for various irradiation conditions. A ve ra ge fl ux , n /c m 2 Neutron Energy, MeV Fig. 5. Neutron spectrum in carbon cell with FD averaged over cell volume C on ce nt ra tio n Tc , % 99 Irradiation time, days FP C RAW Pb RAW PbRAW C He neutrons alter moderator Fig. 6. 99Tc concentration change versus time for various irradiation conditions Evidently for separated irradiation (80% FP + 10% C+ 10% He) 99Tc undergoes almost no transmutation. The same dependencies were obtained for 129I and 135Cs. CONCLUSIONS For the given geometry and using mathematical simulation we have determined optimal conditions for minor actinides and FP transmutation under joined and separated irradiation by 14 MeV neutrons. Further investigations are necessary to find optimal conditions for separated irradiation avoiding strong attenuation of neutron flux. REFERENCES 1. V.A. Mahova, I.D. Sokolova, N.A. Shulga. Studies on fractioning and transmutation of long-lived radionuclide. Review // Atomnaya tehnika za rubezhom. 2003, №3, p. 3-10 (in Russian). 2. http://www.nea.fr/html/dbdata/eva/evaret.cgi. 3. R.P. Slabospitskiy, M.A Khazhmuradov. Calculation of the transmutation of the radioactive wastes main elements using the thermonuclear neutrons // Sbornik nauchnyh trudov SNIYaEiP. 2007, 4(24), p. 207-215 (in Russian). 4. Y.V. Rudychev, R.P. Slabospitskiy, M.A. Khazhmuradov. Physical background and modeling of facility construction for transmutation of some elements of radioactive waste using thermonuclear neutrons // The Journal of Kharkiv National University. Physical series “Nuclei, Particles, Fields”. 2008, №604 (in Russian). 5. R.A. Forrest. FISPACT-2003: User manual, UKAEA FUS 485, 2002. Article received 22.09.08. ИССЛЕДОВАНИЕ ВОЗМОЖНОСТИ ИСПОЛЬЗОВАНИЯ ТЕРМОЯДЕРНЫХ НЕЙТРОНОВ ДЛЯ ТРАНСМУТАЦИИ РАО Е.В. Рудычев, Р.П. Слабоспицкий, М.А. Хажмурадов Рассматривается два варианта системы трансмутации радиоактивных отходов (РАО) с помощью термоядерных нейтронов. В одном – трансурановые элементы и продукты деления не отделены друг от друга, в другом варианте – облучаются раздельно. Проанализированы преимущества и недостатки каждого из вариантов. Выполнено моделирование систем трансмутации РАО. Проанализирована эффективность трансмутации РАО для каждого из вариантов. Подготовлено физическое обоснование для трансмутации РАО термоядерными нейтронами. ДОСЛІДЖЕННЯ МОЖЛИВОСТІ ВИКОРИСТАННЯ ТЕРМОЯДЕРНИХ НЕЙТРОНІВ ДЛЯ ТРАНСМУТАЦІЇ РАВ Є.В. Рудичев, Р.П. Слабоспицький, М.А. Хажмурадов Розглядається два варіанти системи трансмутації радіоактивних відходів (РАВ) за допомогою термоядерних нейтронів. В одному – трансуранові елементи і продукти ділення не відокремлені один від одного, в іншому варіанті – опромінюються роздільно. Проаналізовано переваги і недоліки кожного з варіантів. Виконано моделювання систем трансмутації РАВ. Проаналізовано ефективність трансмутації РАВ для кожного з варіантів. Підготовлено фізичне обґрунтування для трансмутації РАО термоядерними нейтронами. 69

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