Disposal of radioactive waste by means of nuclear conversion
Nowadays radioactive waste (RW) are being buried in geologic rocks. There is an alternative method of waste disposal. It is a transmutation of radioactive isotopes into stable ones by nuclear reactions with the use of accelerators with a particle energy of 50-1000 MeV. We have shown that neutrons fr...
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
2001
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| Zitieren: | Disposal of radioactive waste by means of nuclear conversion / N.A. Khizhnyak, V.Ya. Migalenya, V.A. Voronko // Вопросы атомной науки и техники. — 2001. — № 5. — С. 188-190. — Бібліогр.: 9 назв. — англ. |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine| _version_ | 1860062996439498752 |
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| author | Khizhnyak, N.A. Migalenya, V.Ya. Voronko, V.A. |
| author_facet | Khizhnyak, N.A. Migalenya, V.Ya. Voronko, V.A. |
| citation_txt | Disposal of radioactive waste by means of nuclear conversion / N.A. Khizhnyak, V.Ya. Migalenya, V.A. Voronko // Вопросы атомной науки и техники. — 2001. — № 5. — С. 188-190. — Бібліогр.: 9 назв. — англ. |
| collection | DSpace DC |
| container_title | Вопросы атомной науки и техники |
| description | Nowadays radioactive waste (RW) are being buried in geologic rocks. There is an alternative method of waste disposal. It is a transmutation of radioactive isotopes into stable ones by nuclear reactions with the use of accelerators with a particle energy of 50-1000 MeV. We have shown that neutrons from spallation reactions have no advantages in comparison with a hard neutron spectrum reactor technology. We have shown that during reprocessing the Th-U reactor RW, where there is a lack of actinide group, the effectiveness of proton beams and neutrons from the spallation reaction for RW disposal may be at the required level.
|
| first_indexed | 2025-12-07T17:05:41Z |
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DISPOSAL OF RADIOACTIVE WASTE BY MEANS
OF NUCLEAR CONVERSION
N.A. Khizhnyak, V.Ya. Migalenya, V.A. Voronko
National Science Center, Kharkov Institute of Physics and Technology,
1, Akademicheskaya, Str., 61108, Kharkov, Ukraine
e-mail: voronko@kipt.kharkov.ua
Nowadays radioactive waste (RW) are being buried in geologic rocks. There is an alternative method of waste dis-
posal. It is a transmutation of radioactive isotopes into stable ones by nuclear reactions with the use of accelerators
with a particle energy of 50-1000 MeV. We have shown that neutrons from spallation reactions have no advantages
in comparison with a hard neutron spectrum reactor technology. We have shown that during reprocessing the Th-U
reactor RW, where there is a lack of actinide group, the effectiveness of proton beams and neutrons from the spalla-
tion reaction for RW disposal may be at the required level.
PACS numbers: 28.41.Kw, 89.60.Ec
Radioactive products are accumulated as a result of
U nucleus fission in the reactors and successive radia-
tion neutron captures. The problem of disposal of ra-
dioactive waste from nuclear power plants has been dis-
cussed in literature since the end of the 60th. On the one
hand it is the most important problem the solution of
which determines the development of the environmen-
tally safe nuclear engineering on the Earth. A number of
variants for this problem be solved has been proposed.
On the other hand, each of suggested solutions is rather
complex from the mechanical point of view and the suc-
cessful realization causes so many problems that up till
now none of proposals has been realized seriously in the
world. There is only the well-known conception of ra-
dioactive waste disposal by burring them in stable geo-
logical rocks after hardening as glass or ceramics. The
tectonic stability of these formations over at least
1000 years should permit to decrease the potential dan-
ger to the acceptable level. And though the areas re-
quired for their storage are relatively small (3000 m2 for
1 GW per year), the social opinion considers such a so-
lution of this problem unacceptable and it is the moving
force to search new more effective methods of radioac-
tive waste transmutation. The solution of the problem is
especially urgent in the Ukraine therefore 13 power re-
actors of 12 GW produce about 30% of all the electrical
energy.
The single reliable and safe method of long-lived ra-
dioactive nuclear waste disposal is the transmutation i.e.
the conversion them into stable isotopes by neutron [1]
or other radioactive radiation. Many of nuclear physical
laboratories of the world are engaged now in basing this
practically admissible method of transmutation but up to
date none of suggested methods has been used. The dif-
ficulty is due to that the quantity of radioactive nuclei in
waste of the atomic industry to be transmutated is rather
high and transmutation of every kind of radioactive nu-
clei requires definite individual conditions, and the as-
sertion of the type that it is enough to place these fission
fragments into a nuclear reactor with a high neutron
density to expose them to effective transmutation evi-
dences on misunderstanding of this process. And the
main condition is that the effective transmutation of ra-
dioactive nuclei is possible only on pure isotopic tar-
gets. Therefore all these variants of transmutation begin
to work after waste fuels are disintegrated into separate
elements and isotopes. In NSC KIPT over many years a
new original method of ion mass separation is devel-
oped and in our opinion this problem should be solved
in the cooperation with other Institutes of the Ukraine.
In [1] the problem of using fission reactors with
high-energy spectrum for lowering content of isotopes
such as Krypton-85, Strontium-90 and Cesium-137 was
considered. In [2] the same problem was researched
supposing that generators of neutrons are protons of the
electronuclear installation. The application of a ther-
monuclear reactor for transmutation was considered in [
3]. All the above mentioned technologies were general-
ized and studied in the well-know work [4] where fol-
lowing conclusions have been made.
Disposing of fission products such as Strontium-90,
Cesium-137, Krypton-85, long-lived radioactive nuclei
(LLRN) with transmutation as a result of multiple cy-
cles of irradiation in existing now and being designed
constructions of nuclear reactors is impossible due to in-
sufficiently high neutron flows for the significant lower-
ing of the effective half-life decay of the aggregates of
these nuclides.
Attainment of this aim requires to create neutron
flows of about 1017 neutron/cm2sec in special reactors.
Possible variants may be only electronuclear reactors,
since even in thermonuclear reactors the neutron flow
density will be of order lower. Moreover, the latter has
not been realized and electronuclear reactors require as
minimum the realization of a wide program of develop-
ments. However, investigations carried out in NSC
KIPT [5] show there is the inaccuracy in BNL papers
quoted. For burning Cesium-137 in the intensive neu-
tron flow with a density of 1017 neutron/cm2sec in the
spectrum of neutrons formed on the target-convertor of
the linear accelerator the radioactive capture cross-sec-
tion will be strongly suppressed by parallel nuclear reac-
tions and therefore the burning time of this isotope in-
creases from 2 to 10 years, that is absolutely unaccept-
able. Additional studies carried out has shown that Ce-
sium-137 isotope can be sufficiently effectively trans-
mutated in direct reactions with protons of rather low
ВОПРОСЫ АТОМНОЙ НАУКИ И ТЕХНИКИ. 2001. №5.
Серия: Ядерно-физические исследования (39), с. 188-190.
188
energies. That conclusion obtained by theoretical meth-
ods gives the practical basis for all the problem of
LLRN transmutation with proton beams of moderate en-
ergies. The idea of radioactive waste transmutation has
the authorship certificate [6].
It was shown earlier [6,7] that there was the princi-
pal possibility for transmutation of long-lived nuclide of
nuclear fuel cycle (NFC) into short-lived stable ones as
a result of nuclear reactions (p, xn yp) under irradiation
radiation of nuclear fuel fission products with protons of
the energy lower than 50 MeV. To estimate the techno-
logical possibility of transmutation (burning) using the
proton accelerators of low energies (Ep<100 MeV) it is
necessary to have information about nuclear constants
of proceeding nuclear physical processes. In preliminary
estimations the results of calculations for cross-sections
of long-lived radioactive fission product burning are
given and the value of the energy consumption for NFC
fission product transmutation with low-energy protons
is considered.
To carry out the analysis of fission product transmu-
tation with proton beams of the energy less than
50 MeV the calculations for functions of excitation re-
actions (p, xn, yp) of on nuclei 85Kr, 88Sr, 90Sr, 99Tc,
107Pd, 133Cs, 137Cs, 151Sm have been fulfilled. Calcula-
tions were made according to the statistical model of the
compound nucleus taking into account the preequilibri-
um decay [8]. From results obtained it follows that
when 85Kr, 90Sr, 167Pd are irradiated with proton beams
of the energy Ep<50 MeV, stable and short-lived nu-
clides are formed. 99Tc irradiation with Ep<25 MeV
proton beam results in formation of radioactive nuclei
97Тс, 96Tc and 93Mo with half-life 4.6·106 years and
3.5·103 years, respectively.
During irradiation of 137Сs with Ер>30 МeV the re-
action channels (р, 5n) and (p, p2n) are opened leading
to production of 133Ва (Т1/2=10.54 y.) and 135Сs
(T1/2=2.3·106 y.), and for 151Sm in all the energy range
the production of long-lived nuclides takes place.
In the process of transmutation of fissile products
without isotope separation the stable isotopes of a given
element will transmutate into other nuclides often being
radioactive ones.
Calculations results for functions of excitation of re-
actions proceeding on stable isotopes 88Sr and 133Cs
show that the maximum value of Т1/2 nuclides formed
during proton interaction with 88Sr is 106.6 days, and in
case of 133Cs it is 10.54 yeas, i.е. an additional quantity
of long-lived nuclides is produced that lowers transmu-
tation effectiveness. Total reaction cross-sections of 88Sr
and 133Cs approach to those of radioactive nuclides of
strontium and cesium that results in the additional ex-
pense of an accelerated beam for reprocessing. General-
ly, independently on the transmutation method the burn-
ing of NFC long-lived fission products without isotope
separation will lead to increasing the power consump-
tion, to say nothing of possibility of new nuclide pro-
duction. Under these conditions in some cases it can be
more advantageously to carry out transmutation on iso-
topically enriched targets.
Let us consider the energy consumption for transmu-
tation with low-energy protons (<50 MeV). In above-
mentioned energy range the relation of probability of
nuclear interactions and ionization is <10-2. Energy con-
sumption for transmutation of only one nucleus will be
of order of 102 Ер/ηy, where Ер is the accelerated beam
energy, ηy is the efficiency of the accelerator itself. For-
mation in a power reactor of one nucleus gives the use-
ful energy equal to Еfηp/Y, where Еf is the decay energy,
ηp is the efficiency of a reactor, Y is the output per one
fission. The expedient transmutation from the viewpoint
of power will be defined as follows:
Efηp/Y>102
*Ep/ηy.
Hence we obtain the limit on a cumulative NFC fis-
sion product yield:
Efηpηy/102Ep > Y.
Assuming Еf=200 MeV, ηp=0.3, ηy=0.5 we obtain
Y < 0.3/Ep.
This equation shows that it is advantageous to use a
lower energy of accelerated beam. In < 50 MeV energy
range the optimal transmutation energy value is
15-20 MeV, that range where for NFC fission products
the maximum of (р, 2n) reaction yield takes place and
its value is near the total proton absorption cross-sec-
tion. Taking Ер=20 MeV one obtains the output for
which the energy balance is reached, Y=1.5%, i.е.,
product transmutation is energetically profitable with
Y<1.5%.
The result obtained is valid only for a monoisotopi-
cal target. In case of transmutation without isotope sepa-
ration the limitation for transmutated nuclide yield will
be
Y < 1.5·10-3σTcT/(Σciσi),
where σT is the transmutation cross-section, ст is the
transmutated nuclide concentration and ci and σi are the
concentrations and total reaction cross-sections of other
isotopes in the mixture.
We have shown [6] that during irradiation of nuclear
fuel segments with protons of the energy less than
50 MeV as a result of (р, хn yp) nuclear reactions long-
lived nuclides transmutate into short-lived and stable
ones with the total transmutation cross-section of
1 barn. So, for 137Cs proton beam energy of 20 MeV
there are following reactions leading to stable and short-
lived nuclides:
137Сs(p, n)137Ba; 137Cs(p, 2n)136Ba; 137Cs(p, 3n)135Ba;
137Cs(p, pn) 136Cs −−→ (β–, 13 суток) 136Ba;
!37Cs(p, αn) 133Xe −−→ (β–, 5,29 суток) 133Cs.
The calculation of these reaction cross-section made
on the statistical model of the compound nucleus taking
into account the preequilibrium decay gives the total
cross-section of above mentioned reactions 1.03 barn.
Under irradiation of radioactive nuclei with a parti-
cle beam of the flow density ϕ there are two processes
leading to decreasing the nucleus-target number: the
process of the natural radioactive decay λ and nuclear
reactions transmutating the initial nuclei into other nu-
clides with the cross-section σ. In this case a half-decay
period of the initial nuclide will be as
Т1/2 = ln2/(λ + σϕ).
At the proton 20 MeV beam density the on a cesium
ВОПРОСЫ АТОМНОЙ НАУКИ И ТЕХНИКИ. 2001. №5.
Серия: Ядерно-физические исследования (39), с. 188-190.
189
target 2·1017р/сm2s (about 32 mА/сm2) we obtain
Т1/2=0.106 year. Since the initial amount of 137Cs (and
90Sr), contained in one ton of a spent fuel in 1000 times
exceeds the activity of 1 Т natural uranium then the irra-
diation time for decreasing the activity in 1000 times
will be 10 Т1/2, i.е., in the given case it will be 1.06 year,
that corresponds to the optimal time of transmutation as
is mentioned above.
The number of nuclei transmutated during the time t
for the initial quantity No is
N = No[1 – exp(–σϕt)].
We take No equal to the production of 137Cs in reac-
tors WWER of 1000 MW (el.)–3.3·1026 nuclei per year.
Then under irradiation during a day we have the amount
of transmutated nuclei equal to 5.8·1024. Production of
137Cs during twenty four hours is 9·1023 nuclei. Thus,
such an approach permits, in principle, to transmutate
long-lived waste with processing both newly formed
and storaged ones.
The energy consumption is the essential moment. In
the above proton energy range the relation of probability
of nuclear interaction is about 10-2, i.e. to transmutate
one 137Cs nucleus it is necessary to accelerate about 100
protons. Then the energy consumption for transmutation
of one nucleus is Wexp.=20·100=2 GeV.
So, inasmuch as for fission of one nucleus 235U in the
reactor the 137Cs nucleus is formed with a probability
6·10-2, then the «useful» energy released in reactor dur-
ing formation of one 137Cs nucleus we define as
Wf.=200/6·10-2=3.3 GeV. Taking into account the accel-
erator efficiency (<50%) and the reactor efficiency
(30%) we have the relation Wexр./Wf.>4.
The possibility to decrease the energy consumption
for transmutation can be achieved: in the process of re-
cuperating the energy of the beam passed through the
target (the thickness of which must be less than the ac-
celerator proton path) using an accumulation ring pro-
posed by Ado et al. [9], where after passing the target
the beam is accelerated again for compensation of the
energy loss. It is the realization of the target as a plasma
of sufficiently high density. The choice of more except-
able method of decreasing the energy losses is possible
only after the comparative analysis of the above meth-
ods.
Therefore to solve the problem of NPP long-lived
waste transmutation with low- energy proton beams one
should solve the following questions:
•theoretical analysis of processes of proton interaction
with long-lived nuclear fission products with the aim to
choose an optimal beam parameters;
•development of a method of decreasing unproductive
losses of the beam energy in the process of transmuta-
tion;
•experimental investigations of transmutation processes
to correct the theoretical estimations of nuclear reaction
cross-sections in the process of transmutation.
Finally, radioactive waste of nuclear power plants
can be transmutated with the use of accelerators into
stable isotopes excluding the actinide group. For this
purpose two group of accelerators are necessary – accel-
erators of the electric nuclear breading (proton accelera-
tors with the energy of 1-1.5 GeV and average current
of 0.1 А) and accelerators the construction of which is
possible already nowadays (proton accelerators with the
energy of 100-300 MeV and mean current 0.001 А).
However, transmutation with accelerators is possible
only on monoisotopic targets therefore together with ac-
celerators high- efficiency separators of radioactive
waste should be created. Theoretical and experimental
investigations have been organized on each trend and at
a physical level promising results were obtained.
REFERENCES
1.M.V.Steinberg, G.Wotzak, B.Manowitz. Neutron
burning of long-lived fission products for waste dispos-
al. BNL-8558, Brookhaven Nat. Lab., Upton N.Y.,
1958.
2.M.V.Gregory, M.V.Steinberg. A nuclear transmuta-
tion system for the disposal of long-lived fission product
wastes. BNL-11915, 1967.
3.W.C.Wolkenhaner. The controlled thermonuclear re-
actor as a fission product burner // Trans. of the Am.
Nuclear Society. 1972, p. 151.
4.H.C.Claiborn. Neutron-induced transmutation of
high-level radioactive waste. 1972, ORNL-TM-3964,
Oak Ridge, Tenessee.
5.V.Ya.Kostin, V.Ya.Migalenya, M.G.Shatnev,
A.N.Lvov // Atomnaya energiya. 1981, v. 51, # 5, p. 336
(in Russian).
6.V.Ya.Kostin, V.Ya.Migalenya, A.N.Lvov,
N.A.Khizhnyak. Authorship Certificate №950073, 704,
1982 (in Russian).
7.J.A.Ogedele. Some energetics considerations of fis-
sion product transmutation with protons. Atomkernen-
ergie / Kerntechnik, 1981, b. 39, p. 175.
8.M.Blann // Phys.Rev.Lett. 1972, v. 28, p. 757.
9.Yu.M.Ado et al. // Proceedings of V conference on
Charged Particle Accelerator, v. 11, Moscow: Nauka,
1977, p. 317 (in Russian).
ВОПРОСЫ АТОМНОЙ НАУКИ И ТЕХНИКИ. 2001. №5.
Серия: Ядерно-физические исследования (39), с.188-190.
190
|
| id | nasplib_isofts_kiev_ua-123456789-79025 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 1562-6016 |
| language | English |
| last_indexed | 2025-12-07T17:05:41Z |
| publishDate | 2001 |
| publisher | Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| record_format | dspace |
| spelling | Khizhnyak, N.A. Migalenya, V.Ya. Voronko, V.A. 2015-03-24T18:38:41Z 2015-03-24T18:38:41Z 2001 Disposal of radioactive waste by means of nuclear conversion / N.A. Khizhnyak, V.Ya. Migalenya, V.A. Voronko // Вопросы атомной науки и техники. — 2001. — № 5. — С. 188-190. — Бібліогр.: 9 назв. — англ. 1562-6016 PACS numbers: 28.41.Kw, 89.60.Ec https://nasplib.isofts.kiev.ua/handle/123456789/79025 Nowadays radioactive waste (RW) are being buried in geologic rocks. There is an alternative method of waste disposal. It is a transmutation of radioactive isotopes into stable ones by nuclear reactions with the use of accelerators with a particle energy of 50-1000 MeV. We have shown that neutrons from spallation reactions have no advantages in comparison with a hard neutron spectrum reactor technology. We have shown that during reprocessing the Th-U reactor RW, where there is a lack of actinide group, the effectiveness of proton beams and neutrons from the spallation reaction for RW disposal may be at the required level. en Національний науковий центр «Харківський фізико-технічний інститут» НАН України Вопросы атомной науки и техники Disposal of radioactive waste by means of nuclear conversion Уничтожение радиоактивных отходов с помощью ядерных превращений Article published earlier |
| spellingShingle | Disposal of radioactive waste by means of nuclear conversion Khizhnyak, N.A. Migalenya, V.Ya. Voronko, V.A. |
| title | Disposal of radioactive waste by means of nuclear conversion |
| title_alt | Уничтожение радиоактивных отходов с помощью ядерных превращений |
| title_full | Disposal of radioactive waste by means of nuclear conversion |
| title_fullStr | Disposal of radioactive waste by means of nuclear conversion |
| title_full_unstemmed | Disposal of radioactive waste by means of nuclear conversion |
| title_short | Disposal of radioactive waste by means of nuclear conversion |
| title_sort | disposal of radioactive waste by means of nuclear conversion |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/79025 |
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