5 FIELD OF INVENTION

The present invention refers to the field of application of high energy nuclear radiation and more exactly to a method of utilizing the K capture process caused in different elements

10 by application of high energy electrcns, wherein a target is prepared from a first element ar arranged under influence of a source of radiation. The method of the invention results in the possibility of making use of t e different kinds of the electron accelerators, regardless to their kind, whereby the

15 economy of operating the different accelerators can be re¬ markably improved. The proposed method can be realized with accelerators of diverse kinds, especially for decomposing some kinds of dangereous radioactive -.caste components, for producing rare and expensive materials, elements, and for energetic pur-

20. poses.

BACKGROUND OF THE INVENTION

It is known from the literature that the K capture pre— 5 cess causes the reduction of the atomic number by one. In this process the atonic nucleus receives an electron transforming a proton into a neutron. The nucleus thus transformed emits a neutrino and energy. For example, the K capture transformation of beryllium results in emission cf a neutrino (v) and charac- 0 teristic radiation of energy about Q = 0.66 eV and in receiv¬ ing the nucleus of lithium:

⁷ Be(e ^" ,v) ³ ₇ Li + Q.

In the theory of the atomic nuclei the possibility of

A4583-5903/1/NE-Ko

carryir-g out the processes of this kind is mentioned, some ex¬ amples can be found, too.

The transformation of nuclei is well-kr.own, per se, and especially by the means of the (n, gaπnia) reaction. This reac- "_ion is the basis of producing the very important Co 60 cobalt isotope applied in many fields of medicine and industry. The end product is a very intensive radiation source therefore the In, gaπna) process requires in the regular applications special security measures in order to avoid the very iangereous radio- active contamination of the environment.

By the means of the (n, gamma) reacticr, the atomic num¬ ber can not be changed in one step. It is possible, as e.g. in the case of platinum that the Pt 196 platinurr. isotope that the process results in activating the basic isotcpe, in transform- ing it into an intermediate isotope showing a decay process ending in the nucleus of an element differing from that of the first element (the activation gives the Pt 197 isotope decaying with half-period about 20 hours to the Au 196 gold isotope. In rjost cases, the (n, gamma) reaction is expensive and incon- venient because of the high level radioactive radiation repre¬ sented or generated by the neutrons. It has been proposed to apply only the thermal neutrons for producing materials, mixtures of elements showing very low level radioactivity. This can be done e.g. by arranging a target consisted of Yb 70 and/or W 74 isotope in the way of a thermal neutron flux.

The process of transformation of nuclei by the means of the (n, gaπma) reaction is limited to a relatively small group • of elements.

SUMMARY OF THE INVENTION

The object of the present invention is to make use of high energy electrons in the electron accelerators for produc¬ ing some expensive elements and isotopes, further for inac- tivating some radioactive waste components, especially pluto—

niu and uranium produced in nuclear reactors.

The invention is based on the recognition that the K capture process offers a very advantageous possibility of transforming atomic nuclei,• hereby it is possible to gain also supplementary energy amounts.

Hence, the invention is a πethod of utilizing the K cap¬ ture process by the means of high energy electrons, comprising the step of preparing a target ccr_sisted of a first element, the novelty of which lies in the further steps of (a) ionizing the atoms of "the first element for producing nuclei to be transformed into the nuclei of a second element by removing at least one electron from at least one electron shell of the atom, (b) introducing electrons of advantageous energy lying over 1 MeV into the nuclei, substantially at least one electron into one nucleus, and (c) completing the shell with the elec¬ trons, wherein (d) the first element is lithium, arsenic, tita¬ nium, ruthenium, palladium, silver, caesium, sararium, gadoli¬ nium, dysprosium, ytterbium, tantalum, iridium, plutonium, gold, mercury, plutonium or uraniin. In the most advantageous embodiments of the method of the invention the step of ionizing the atoms of the first ele¬ ments by preparing a plasma thereof or by making the atoms cross a thin metallic foil or by bombarding then with positrons advantageousaly of energy below 1 MHz. In a further advantageous embodiment of the method pro¬ posed by the invention the step of making the ionized atoms to move in a toroid shaped accelerating arrangement and introduc¬ ing the electrons into the nuclei during one turn thereof with¬ in the accelerating arrangement. In neutralizing the by-products of different nuclear plants and arrangements it is proposed to select the first ele¬ ment as uranium or plutonium obtained as radioactive waste from a nuclear reactor.

The method of the invention can be advantageously app- lied for producing materials being more expensive than the

first element if the first element is arsenic-, ruthenium, sil¬ ver, caesium, samarium, tantalum or gold.

In a further preferred embodiment of the method proposed by the invention the production of energy is possible if the first element is especially lithium, but it may be also cae¬ sium, tantalum or gold.

The method of the invention of ers a very advantageous possibility of producing expensive materials.

The invention will be further described by presenting some preferred embodiments in more detail.

DETAILED DESCRIPTION OF THE INVENTION AND PEEFEREΞD EMBODIMENTS

In the first step of realizing the method of the inven- tion an appropriate first element should be selected according to the object determined. In neutralizing by-prcducts of dif¬ ferent nuclear plants and arrangements it is proposed to select the first element as uranium or plutonium obtained as radio¬ active waste from a nuclear reactor. If a secrnd ^' element being more expensive or rare than the first is to be generated, then the is advantageously arsenic, ruthenium, silver, caesium, sa¬ marium, tantalum or gold. The method proposed by the invention offers in limited extent the possiblity of producing energy when the first element is especially lithium, but it may be also caesium, tantalum or gold. The first element is selected rather to be an appropriate isotope the transformation of which can result in a stable isotope of the second element. Hence, it is possible to obtain the first element in the form of an isotope produced by irradiating a stable isotrpe with epither- mal, thermal or resonance neutrons.

The basic object of the invention is t generate a sec¬ ond element by the K capture process from a first element. This process is possible rather after ionizing the first element, and the ionization should result in.removing as many electrons from the electron shells of the atom as possible. This means,

an atom of an element having atomic number Z can be ionized up

Z+ to the extent Z (i. e. at most Z, generally maximally four¬ teen electrons can be removed from the atom by decomposing at least one or all shells). However, ir. the present conditions. the number of the electrons removed from the shells is gener¬ ally ot higher than-14. The ionization can be ensured by known means, among others by forming a high temperature plasma from the atoms, by passing the atoms thrcugh a thin metallic foil. These means may be, however, sometimes disadvantageous because of the high temperature ionization. A more preferred possibi¬ lity is to irradiate the atoms by positrons obtained from _an appropriate source, as an accelerat r or Na 22 isotope.

In the practice the ionizing process to be carried out by the means of electrons can be realized in a chamber con- nected with a toroid shaped arrangement wherein the chamber re¬ ceives the atoms to be ionized which are irradiated here with positrons of relatively low energy, lying rather below 1 MHz. (The higher energy positrons cross the atoms of the first ele¬ ment without remarkable interaction, i.e. low intensity ioniza- tion will be ensured). The ionized atoms flow to the toroid ar¬ rangement.

The K capture reaction itself follows under the influ¬ ence of electrons of relatively high energy exceeding 1.0 MHz which have to enter the nuclei of the ionized atoms. The nuc- leus receives one electron resulting in transformation of one proton into a neutron and a neutrir.c. Some energy can be li¬ berated, too.

Hence, the nucleus having atomic number Z - 1 is ob¬ tained and a further electron' source is applied for completing the electron shells decompleted or removed by ionization, for reconstructing the electron shell system according to the feat¬ ures of the atoms constituting the element generated in this process.

It is possible that the nucleus generated by the K cap- ture process from the first elemeπu is also an instable iso-

tope. It can be stabilized e.g. by the mear^s of thermal neut¬ rons. The method as proposed is, hovever, capable of creating conditions for generating such isotopes of certain elements which are themselves not stable but for some reasons very irr portant. So, the msthod of the invenτicr. offers the possibility of producing isotopes of technetium d prometium.

Some examples of realizing the method of the present in¬ vention can be summerized according ^~ o the following:

A. Arsenic to germanium:

The isotope As 75 of arser-ic C-j As) is activated by neutrons to As 76 and the last is transformed into stable iso¬ tope Ge 76 of germanium ( p e) by a K capture reaction. The arsenic consists practically of isotope As 75 only, so this is a convenient way of preparing the stable isotope Ge 76 consti- tuting about 7.76 wt% of germanium ΞS it can be found in the nature.

B. Ruthenium to technetium:

The isotopes Ru 98 and Ru 99 cf the ruthenium ( _;/ Ru) can be transformed by K capture reactions into the respective iso- topes Tc 98 and Tc 99 of tec-hnetium . _Λ IC, both are isotopes to be found also in natural conditions in the stars but not on the Earth - they may have very important applications).

C. Silver to palladium:

The isotopes Ag 197 and Ag 1C giving the natural com- position of silver ^.yAg) can be activated by a (n, gamma) re¬ action to respective isotopes Ag 198 and Ag 110 which under¬ going a K capture reaction result ir_ the isotopes Pd 108 and ?d 110 of palladium (^Pd) constituting respectively 26.71 wt% and 11.81 wt% of palladium as it can be found in the nature. (Nowadays, palladium is about 25 times more expensive than sil-. ver).

D. Caesium to xenon:

The isotope Cs 133 of caesium ^' _-Cs) can be transformed by a K capture reaction into the isotope Xe 133 of xenon (_- [e) with the half-decay about 5.27 days -whic is transformed also

by an (n, garna) reaction into the stable isotope Xe 134. For a weight unit xer.cn costs about 25 times mere Than caesium.

E. Samarium to palladium:

The iscτcpes Sm 144 and Sm 147 of samarium (g _p Sm can z be -Transformed by K capture reactions into isotopes Phi 144 and

Pm "47 of palladium (^.Pm) which are important in different applications as radioactive isotopes shownir_g half-period about 450 days and l.z-v years, respectively.

F. Tantalum to hafnium: 0 The isotcpe Ta 181 of tantalum (73- _ can be transformed by a K capture reaction into the isotcpe Ξf 181 of hafnium ( ₇₂ Hf) having half-period 44.6 days and teir_g transformable by an (n, gamma) reaction into the isotope Kf 182. This isotope having half-period about 8.10 years finds different app- ! lications zsά is about 15 times more expensive than the- tantalum practically consisting of the sir_gle isotope Ta 181 (it comprises The isotope ₇ ^Ta in only 0...1Z3 wt%).

G. Gold to platinum:

By ensuri-rig an (n, gamma) reaction th . isotope Au 197 of gold ( _7Q AU) - instituting the whole composition of the natural gold - can be activated to the isotope Au 98 which is trans¬ formed by a K capture reaction into the stable isotope Pt 198 of platinum (-.r-Pt). The platinum is about double so expensive than gold. It can be seen that the transformation processes shown above are all represented by the general formula:

Z(e ^~ ,n+v)Z-1 , preceded cr fallowed by an (n, gamma) reaction, wherein Z re¬ presents the nucleus of the first element with atomic number Z, Z - 1 shows the nucleus of the second element with atomic num¬ ber lowered by :ne, v means the neutrino, and the transforma¬ tion of a protcπ into neutron is not shown (this takes places in the nucleus rf the first element).

Of course, the possibilites given above are only ex-

amples and the invention is net limiτed to transformation processes wherein only one electron is captured by a nucleus. In given condiTions, and especially in the case of heavy ele¬ ments the atonic number of the nuclei can be lowered also by up to 7. thus, transformation processes in lcng chaines can be de¬ signed.

For neutralizing radiactive waste materials it is pro¬ posed to ionize uranium and/or plutonium and then to ensure conditions wherein the nuclei of these elements can undergo X capture reactions at least five times in order to produce nuclei of actinium, radon or frar.cium. Because of the intensive neutron emission of these processes it is proposed to apply in the environment of the neutralization process metals which are transparent for neutrons, as magnesium, aluminium, zirconium, lead etc.

The third field of application is to produce energy. The decay process of the heavy elements up to the iron (from pluto¬ nium) gives always free energy, but this process is linked with many difficulties. The present invention proposes the apply lithium which will be transformed into helium. It is also very advantageous to apply arsenic, caesium, tantalum and gold for this purpose - the elements mentioned substantially in 100 wt% consist of one isotopes, therefore the method of the invention gives double advantage: the element transformation and the energy production can be carried cut simultaneously.