J. Mod. Phys., 2010, 1, 226-235
doi:10.4236/jmp.2010.14034 Published Online October 2010 (http://www.SciRP.org/journal/jmp)
Study of the Electric Explosion of Titanium Foils in
Uranium Salts
Leonid I. Urutskoev1,2, Dmitry V. Filippov1
1RECOM, National Research Center “Kurchatov Institute”, Moscow, Russia
2Moscow State University of Printing Arts, Moscow, Russia
Received June 9, 2010; revised July 27, 2010; accepted August 2, 2010
Abstract
The results of experiments on electroexplosion titanic foil in water solutions of salts of uranium are pre-
sented in this paper. It is shown, that as a result of electroexplosion occurs appreciable (to 20%) distortion of
an initial isotope parity of uranium. In the most solution parts, observable isotope distortion occurs in favour
of enrichment by 235U. At the moment of electroexplosion it was not observed an appreciable stream of the
neutrons. By means of Cs label and by methods by α, β, γ-spectrometry and mass-spectrometry it have been
shown, that isotope distortion occurs at the expense of non-uniform “disappearance” of both isotopes from a
solution. The isotope distortion leads to infringement of the 234Th secular equilibrium in the uranyl solution.
The equilibrium infringement between the 234Th and 234mPa, i.e. within the proper thorium decay chain, was
observed also. The assumption about that the effects are caused of low-energy nuclear reactions at the mo-
ment of electroexplosion is suggested.
Keywords: Electric Explosion, Nuclear Decay
1. Introduction
Currently, it is beyond doubt that strong external elec-
tromagnetic fields can considerably change the probabil-
ity of nuclear decay and even change the conditions of
nuclear stability [1-7]. For example, complete ionization
of 187Re increases the probability of -decay (due to de-
cay to a bound electron state) [2], while complete ioniza-
tion of stable isotopes 163Dy, 193Ir, 205Tl makes them
–-active (the half-life time of completely ionized 163Dy
was 47  5 days [3]). Now it is clear that strong external
fields affect to one or another extent the probabilities of
all nuclear processes, the major effect being mediated by
deformation of the atomic electron states (both occupied
by electrons and free) [4-7]. This influence depends ap-
preciably on the decay type and energy, on the degree of
prohibition, and, in the general case, on the spins and
evenness of the initial and final states of the decaying
nucleus. In some cases, the dependence of the change in
the decay probability on the intensity of external action
can be non-monotonic. Usually, the effect is stronger for
hindered (forbidden) decay channels but it is noteworthy
that a change in the decay probability induced by exter-
nal fields depends on many parameters and every nu-
cleus is in a certain sense unique. For the nuclei that de-
cay along several channels having different parameters
and degrees of prohibition, the effect of external fields
changes the ratio of decay intensities along different
channels. When the fields act on a substance containing a
mixture of isotopes, the final ratio of the radioactive iso-
topes should change as the effects may be different for
different isotopes.
It is known that high-current electric explosion of metal
wires in a liquid induces strong magnetic fields (H ~ 1
MG) and high pulse pressures (Р ~ 105 atm) [8,9]. To
study the effect of external action on the decay of ura-
nium series isotopes, we carried out experiments on the
electric explosion of titanium foil in a solution of uranyl
sulfate in doubly distilled water. The very idea to inves-
tigate impacts of strong electromagnetic fields on the
uranium isotopic decay dawned on the authors of this
articles resulting from multiple and repeated attempts to
grasp the physical mechanism of nuclear reactor runaway
which actually took place in the Chernobyl NPP in 1986
[10]. The results of preliminary experiments of this series
were published previously [11].

L. I. URUTSKOEV ET AL.
227
2. Description of the Experimental Setup
The experiments outlined below were carried out using
one of the capacitor banks of the setup described in detail
previously [12]. The energy store of the setup was W ~
22 kJ, the charge voltage was U = 4.8 kV, the current
amplitude was I ~ 120 kA, and the pulse duration was 
 130 s. Unlike the explosion chamber used previously
[12], the explosion chamber presented in Figure 1 was
sealed and allowed mounting of only one electrode. The
internal part of explosion chamber 1 was made of poly-
ethylene and was arranged in a lower part of a tough
stainless-steel case 2, which ensured air tightness. The
voltage was supplied through the upper part of a metal
container, which served simultaneously as a gas-col-
lecting chamber 3 with the volume V ~ 3 ℓ (prechamber).
The gas-collecting chamber is required due to the fact
that all attempts to make the gas-water mixture formed
during current passage stay in the explosion chamber
failed, resulting only in the collapse of the explosion
chamber. In a number of experimental series, a pre-
chamber made of organic glass was used to provide the
possibility of high-speed optical recording.
Uranium solution 4 with the volume υ ~ 20 cm3 was
poured into the internal part of explosion chamber 1.
Two types of solutions were used, namely, a solution of
uranyl sulfate enriched in 235U and a solution of uranyl
nitrate with the natural isotope distribution of uranium.
The concentration of the uranium solutions used in ex-
periments varied from 10–2 to 10–1 g.-mol/liter. A bulk
central titanium electrode 5 bearing foil 6 welded to it
1
2
3
4
5
6
7
8
Figure 1. Schematic drawing of experimental setup:
1–interior of the explosion chamber; 2–stainless steel frame;
3–gas-collecting chamber; 4–liquid; 5–titanium electrode;
6–titanium foil; 7–tightening; 8–lid.
was immersed in the solution. Thus, the welded foil
acted as a cable armoring short-circuited to the cable
central core. The amount of the titanium foil (load) var-
ied in different experiments from one to four 1 cm-wide
bands, each with the thickness ∆ = 50 μm and the length
L = 4.0 cm. The weight of each band was m = (90  5) 
10–3 g.
The discharge parameters were monitored using coax-
ial shunts and a voltage-ratio box to record current and
voltage pulses. The signals were recorded by means of
an AD converter with a sampling rate of 1 GHz. Typical
current and voltage oscillograms were presented in our
earlier publications [12,13].
It is well known that electric explosion of a conductor
in water produces an intense electromagnetic radiation
[8,9], which requires taking special measures to provide
the interference immunity of the signals. Note that if an
uranium solution is used as the liquid in electric explo-
sion, the level of electromagnetic radiation increases by a
large factor, especially in the second half of the pulse
duration.
During current passage, -radiation was recorded. This
was done by scintillator-based detectors (NaI, CsI) and
photomultipliers, which were placed 1.5 to 2 meters
away from the location of electric explosion. No notice-
able excess over the background -radiation during the
current pulse was detected.
The neutron yield was also monitored. For sufficiently
efficient recording of fission neutrons, a special neutron
detector was assembled from nine slow neutron counters
(СНМ-17). The whole assembly was surrounded by a 8
cm-thick polyethylene moderator. The electromagnetic
interference immunity was provided by placing the
whole detector block together with preamplifiers inside a
copper screen. For elimination of false pulses (com-
mon-mode interferences), the slow neutron counters
were split into two groups.
3. The Procedure of Measurements
For determining the efficiency of neutron detection, a
neutron calibration source 252Cf was placed in the explo-
sion chamber. The measured detection efficiency of fis-
sion neutrons was 0.04%. Every detected pulse was iden-
tified as a neutron if it coincided with the pulse from the
calibration source in the shape and amplitude. It follows
from the measurements that the neutron flux after elec-
tric explosion did not exceed I  103 neutrons per pulse.
Note that in the experiments using organic glass pre-
chamber 3, the neutron detector also recorded some
pulses other than neutron pulses. Figure 2(а) shows a
neutron signal from the calibration source and a typical
“false” signal. It follows from Figure 2 that duration of

L. I. URUTSKOEV ET AL.
228
(a)
(b)
Figure 2. Signals of the neutron detector: (a) a typical distribution of the signals in time; (b) a “false” pulse and the pulse
from the calibration source.
the “false” pulse differs by a factor of about 2 from the
neutron pulse duration. This difference is manifested in
both electronic and ionic components of the signal. The
number of detected “false” pulses was much greater than
the number of neutron pulses. A typical distribution over
the times of signal arrival to the detector is shown in
Figure 2(b). As regards the shape, the “false” signals
resemble -quanta, which were also detected by the neu-
tron detector, although with a lower efficiency. However,
these signals could not be identified as -quanta as in this
case, they would have been detected much more effi-
ciently by -radiation detectors. These signals could not
be attributed to the electromagnetic pickup either, be-
cause they were detected after operation of the capacitor
battery. The nature of the “false” signals remained ob-
scure but there is more evidence for their electromag-
netic origin than for nuclear origin.
Upon application of current pulses on a titanium foil,

L. I. URUTSKOEV ET AL.
229
the foil explodes and the pressure in the explosion
chamber sharply increases. For this reason, most of the
uranium solution breaks to prechamber 3 through seal 7.
This gives two different solution volumes, and, accord-
ing to preliminary results [11], they differed substantially
in the isotope composition of uranium. For this reason,
sampling of the uranium solution after the “shot” was
performed from both upper (hereinafter “up”) and lower
(hereinafter “lw”) volume. For convenience of collecting
the solution, special groove was envisaged in the poly-
ethylene lid 8.
The samples were taken by a disposable syringe,
placed in standard 2-mℓ or 5-mℓ plastic tubes and imme-
diately sealed by PARAFILM “M”. The dosage accuracy
was relatively low being equal to ~5%. Therefore, the
measured volumetric activity values were used only for
rough estimates and the results of , , and  spectrome-
try measurements were represented as ratios of the val-
ues obtained in one and the same measurement. This
presentation of measurement results ensured minimiza-
tion of possible errors caused by dosage errors.
In order to avoid procedural errors and to enable com-
parison of the results of measurements of the same val-
ues obtained by different procedures, two samples with
identical volumes were measured for each procedure.
One sample (reference sample, “rs”) contained the initial
solution of uranium for this experiment and the other
sample (experimental sample, “ex”) was the uranium
solution taken from the explosion chamber after the elec-
tric explosion. This made it possible to compare the re-
sults of, for example, - and mass spectrometry for ex-
periments carried out with natural and isotope-enriched
solutions of uranium by plotting the results together as
the ratio R = (235U/238U)ex/(235U/238U)rs.
Laser mass spectrometry was chosen as the procedure
for direct determination of the elemental and isotope
compositions. Having rather high accuracy (10–4-10–5
at%), this procedure gave an error of determination of
trace impurities of about 10-15%. The accuracy of de-
termination of the isotope composition of elements was
1.5-2% for minor isotopes and less than 1% for principal
isotopes, which is consistent with published data [14].
During our study, the samples taken from all “shots”
were measured by mass spectrometry but the most thor-
ough isotope analysis was carried out for the following
chemical elements: Fe, Ti and U. The results of meas-
urements for initial components and samples from one
experiment with a solution of enriched uranyl sulfate are
summarized in Table 1. The errors of measurements of
percentages of all chemical elements and isotopes pre-
sented in Table 1 fall into the corridor of errors dis-
cussed above.
The independent measurements of the uranium isotope
Table 1. Elemental and isotope compositions of the sam-
ples, %.
Control Contr. foil Exp
Na 0.135 0.0000 4.380
Mg 0.001 0.0056 0.170
Al 0.060 0.0032 0.550
Si 0.117 0.0067 0.500
P 0.037 0.0025 0.015
S 49.250 0.0038 3.750
Cl 0.321 0.0044 0.093
K 0.047 0.0050 3.500
Ca 0.034 0.0163 1.970
Ti 0.434 99.8606 80.080
V 0.002 0.0018 0.002
Cr 0.002 0.0121 0.039
Mn 0.005 0.0020 0.023
Fe 0.077 0.0694 0.690
Ni 0.009 0.0060 0.013
Co 0.002 0.0002 0.009
Cu 0.005 0.0002 0.021
Zn 0.011 0.0000 0.045
Zr 0.000 0.0003 0.000
Ag 0.000 0.0000 0.510
U 49.453 0.0000 3.610
235U 21 24.56
238U 79 75.44
46Ti 8.0 8.00
47Ti 7.3 8.07
48Ti 73.8 71.48
49Ti 5.5 6.16
50Ti 5.4 6.27
ratio and concentrations of some of its decay products
were accomplished using liquid scintillation , -spec-
trometry and solid-state -spectrometry procedures.
The counting sample for liquid scintillation spec-
trometry was prepared in the following way. A 10-ℓ

L. I. URUTSKOEV ET AL.
230
aliquot portion of the test solution was thoroughly mixed
with the scintillating solution ULTIMA GOLD AB. The
counting sample obtained in this way was measured by a
TRI-CARB 2550 TR/AB counter (Canberra-Packard)
equipped with a time discriminator of alpha and beta
pulses and a multichannel analyzer. The identification
and activity calculation of isotopes were performed using
a special program Spectradec for spectrum processing,
which makes use of the library of instrumental spectra of
separate isotopes. The result was found by comparing the
studied convoluted instrumental spectrum with this spec-
trum obtained by simulation. This procedure has sub-
stantial errors in determination of most isotopes and,
hence, this analysis was semiquantitative.
The contents of alpha-emitting isotopes were deter-
mined on a standard Canberra -spectrometric complex,
which comprised four -spectrometers of design 7401
with PIPS detectors. The active area of each detector was
600 mm2. The counting sample was prepared by electro-
chemical deposition of the emitters from a solution of
sodium ammonium sulfate at pH ~ 2.2-2.5 onto stainless-
steel polished discs.
To decrease the effect of conversion electrons, the
measurements were carried out at a 14 mm distance from
the detector surface. This effect was manifested as
asymmetry of the right “shoulder” of the peaks of the
instrumental -spectrum, giving rise to an additional
error in their approximation. The average time of meas-
urement was ~1.5  105 s. The quality of the prepared
counting sources was estimated based on 234U peak
resolution at the 4774.6 keV line (yield 72.4%). The en-
ergy resolution of the measurements was at least 23.3
keV, while the contribution of the 234U radiation peak
base to the low-energy 235U and 238U isotopes was less
than 0.1% and could be properly taken into account.
The isotope ratios were calculated from the peak areas.
Since 235U gives rise to seven intense lines which overlap
with all -decaying nuclei present in the mixture (234U,
236U, 238U), this was calculated using the algorithm im-
plemented in RadSpectraDee software. This implies ap-
proximation of peaks by an intricate function combining
an asymmetric Gaussian, an exponent and a hyperbola.
In the -spectrometric procedure, a 40 cm3 germanium
detector and a standard Canberra spectrometer were used.
The energy resolution of the gamma-spectrometer de-
termined from the 137Cs line (662 keV) was 1.8 keV. The
effect of geometric factor on the results was eliminated
by mounting samples right on the detector end face using
a specially manufactured holder. Since the fine titanium
powder suspended in an uranium solution precipitated
over 24 hours and Th was found to interact with titanium
oxides, then in order to avoid additional errors in the
measurements, the uranium solution container was
mounted in a strictly horizontal position relative to the
ground surface. In order to eliminate the possible errors
related to the time drift of -spectrometer parameters, the
experimental and reference samples of uranium solution
were measured in turn.
The spectra were processed in the energy regions of 92
keV (92.38 keV and 92.8 keV are -lines of 234Th, which
is a daughter product of 238U), 1 MeV (1001 keV is the
-line of 234mPa, a daughter product of 234Th) and
186 keV (185.7 keV is the -line of 231Th, a daughter
product of 235U). Single peaks were first approximated
by a Gaussian and then the areas under them were calcu-
lated. The region of -doublet at 92.5 keV shows an
overlap of the 234Th and 231Pa -lines (93.063 keV) with
the K X-ray lines of actinides, resulting in a complex
background. The uranium K1 and K2 X-ray lines ap-
pear due to uranium self-fluorescence, the K2 peak con-
tributing directly to the 92.5 keV doublet. The contribu-
tion of thorium K1 and K2 lines related to 235U decay
was negligibly small. The resolution of the spectrum at
82-102 keV into components was done by a computer
program.
4. Experimental Results
As shown by preliminary studies [11], an electric explo-
sion of titanium foil in a solution of uranyl sulfate in-
duces a distortion of the initial U isotope ratio and dis-
turbance of the 234Th secular equilibrium. Our study con-
firmed the conclusions of the preliminary experiments
and, resorting to additional procedures, provided a more
detailed picture of the phenomenon. The use of both
natural and enriched U in the experiments increased the
accuracy of measurements and provided a more reliable
knowledge of the process. For instance, experiments with
enriched U allowed us to attain a satisfactory accuracy in
determining the uranium isotope ratio by mass spec-
trometry, and the use of natural uranium markedly in-
creased the accuracy of measurement of the uranium
isotope ratio from the ratio of 186/1001 -lines.
When using different procedures we often faced the
so-called “first measurement problem”. In liquid -
spectrometry and solid-state -spectrometry, this was a
distortion of the studied spectrum. In -spectrometry, the
effect was manifested as an increase in the fraction of
conversion electrons, and in -spectrometry, this was
appearance of an additional low-energy  peak. In the
measurements by -spectrometric procedure, the “first
measurement effect” was in the fact that the measure-
ment that was performed first differed most often from
the subsequent measurements by a value markedly ex-
ceeding three standard deviations. After several hours,
even in the second measurement, the effect usually dis-

L. I. URUTSKOEV ET AL.
231
appeared for all procedures.
As reported in a previous study [11], the distortion of
the uranium isotope ratio from mass spectrometry data
averaged over nine runs was Rup = 1.18  0.07 for the
upper sample and Rlw = 0.94  0.01 for the lower sample.
These results could seemingly be interpreted as a usual
separation of U isotopes but the addition of 137Cs radio-
active label to the initial solution ruled out the possibility
of this interpretation. Figure 3 shows the results of
measurements of the upper samples (Rup) obtained by
different procedures. The data were averaged over a se-
ries of 15 runs. It can be seen from the Figure that the
results of measurements by all three procedures are in
satisfactory agreement with one another.
The two rightmost points correspond to -spectrometric
measurement of the concentration of U isotopes with
respect to the cesium label. Thus, it became clear that
uranium enrichment is caused by the fact that the con-
centration of both U isotopes in the solution decreases at
the “shot” instant as a result of some process. Moreover,
the 238U concentration decreases more appreciably than
the 235U concentration, and this is perceived as “effec-
tive” enrichment. The same conclusion can be reached
relying on the data obtained by -spectrometric proce-
dure where an almost twofold decrease in the 238U spe-
cific volume activity was detected in some experiments.
The 235U depletion effect noted for the lower sample [11]
was less pronounced than the enrichment effect of the
upper sample, Rlw  Rup, and could become totally unob-
servable upon a change in the experimental conditions.
For example, upon the addition of heavy water to a solu-
tion of uranyl sulfate (UO2SO4 + 10% D2O), the 235U
depletion effect in the lower sample disappeared to
within the experimental errors, while Rup decreased in-
significantly and remained Rup  1.
The second macroscopically significant effect noted in
[11] was the disturbance of 234Th secular equilibrium
observed in both upper and lower samples almost in all
experiments. However, most often, the disturbance of
234Th equilibrium was more pronounced in lower sam-
ples. Figure 4 shows a typical result of -measurements
for the upper sample from run No.975 illustrating the
disturbance of the 234Th secular equilibrium. The con-
centration of uranium sulfate solution in this run was С =
10–1 mol/ℓ. The result is presented as the time depend-
ence

up
Rt

plotted as the intensity ratio of the 231Th
186 keV line (this line can be regarded as having no time
dependence) to the 92 keV line of 234Th, which is in
secular equilibrium with 238U. The value t = 0 corre-
sponds to the “shot” instant. Figure 4 shows the time
course from T ~ 600 h, which approximately corresponds
to 234Th and 234mPa accumulation periods.
Figure 5 shows the results of time -measurements of
the upper sample for run No.1037 in which a solution of
uranyl nitrate UO2(NO3)2 with the initial natural uranium
isotope distribution was used. The time dependence of
the enrichment factor is represented as the ratio of two
pairs of -lines, up
186 /92
R and up
186 /1001
R. It can be seen
from Figure 5 that the equilibrium between the 92 keV
and 1001 keV -lines was disturbed to a statistically sig-
nificant extent only in the second measurement (the “first
measurement” problem) and the disturbance was retained
for approximately 500 h (approximately the 234Th accu-
mulation period). Then the intensity of both -lines
started to decrease with respect to the reference sample,
Initial
238
235
238
235
U
U
U
U















R
0.7
0.8
0.9
1.0
1.1
1.2
Initial
137
235
137
235
Cs
U
Cs
U















Initial
137
238
137
238
Cs
U
Cs
U















mass-spectrometry
-spectrometry
-spectrometry
Figure 3. Results of measurements of the “upper” samples
(Rup) obtained by different procedures.
Figure 4. Typical result of -measurements of Rup = (I186/
I92.5)ex(I186/I92.5)rs (the sample of run No. 975).

L. I. URUTSKOEV ET AL.
232
Figure 5. The same ratio as at Figure 4, Rup = (I186/I92.5)ex(I186/I92.5)rs and Rup = (I186/I1001)ex(I186/I1001)rs for run No. 1037.
and by approximately the 5000 h after the “shot”, the
equilibrium was restored. The question of whether dif-
ferent chemical compositions of the uranyl solution or
the difference in the initial isotope distribution is respon-
sible for this qualitatively different behaviors remained
open.
5. Conclusions
The key experimental results presented in this paper can
be summarized as follows.
1) The electric explosion of a titanium foil in an uranyl
salt entailed a marked distortion of the initial U isotope
distribution in the solution. The “lower” sample ( ~ 2-3
cm3) shows depletion in 235U (Rlw = 0.94  0.01), while
the “upper” sample ( ~ 10 cm3) shows a more pro-
nounced enrichment (Rup = 1.18  0.07).
2) The processes initiated by the electric explosion re-
sult in a decrease in the specific concentrations of both U
isotopes but the 238U concentration decreases to a larger
extent, giving rise to “enrichment effect”.
3) At the instant of electric explosion, no induced ura-
nium fission is observed and no fission neutrons are de-
tected.
4) Within 1-3 ms after the end of current pulse, gas
counters filled with 3He detected some signals having, in
all probability, electromagnetic origin.
5) At the instant of electric explosion, the 234Th secular
equilibrium in the uranyl solution was disturbed. The
most pronounced disturbance of the secular equilibrium
was observed in “lower” samples, and subsequently the
equilibrium was restored with the period T = 24.5 days.
In the “upper” samples, the 234Th equilibrium was dis-
turbed to a much lesser extent and the time variation was
almost missing.
6) In some experiments, -measurements of the “up-
per” samples revealed disturbance of the equilibrium
between the 234Th 92.5 keV doublet and the 1001 keV
-line of its daughter product, 234mPa, i.e. within the
proper thorium decay chain.
The electric explosion of a titanium foil in a liquid
produces a considerable amount of gases by different
mechanisms (pyrolytic decomposition of water, titanium
oxidation and so on). Thus in the experiments in question,
the pressure in the prechamber (V ~ 3ℓ) increased after
the electric explosion of the foil by ∆P ~ 1 atm. This
should result in an increase in the specific volume activ-
ity of all radioactive isotopes present in the initial solu-
tion. Indeed, the results of measurements carried out by
different procedures (, β, -spectrometry) indicate that
this effect was actually observed in some cases.
However, in most experiments, an unequal decrease in
the specific activity was found for 238U and 235U isotopes.
As noted above, no effect of induced uranium fission
was observed and, hence, this effect cannot be responsi-
ble for the decrease in the specific activity and for the
distortion of the initial uranium isotope ratio.
6. Discussion
On the basis of available experimental data, the follow-
ing interpretation appears most likely. The key processes

L. I. URUTSKOEV ET AL.
233
resulting in the “effective” uranium enrichment take
place in the area of current passage and in the area di-
rectly adjoining the plasma channel, since the major en-
ergy contribution is made in this area and strong mag-
netic fields and high pressures develop at the pulse in-
stant. As regards the space marked by a dashed line in
Figure 1, only a pressure pulse is transmitted there,
which is apparently insufficient to give rise to the “en-
richment” effect. The amount of the solution remaining
on the bottom of the explosion chamber after the electric
explosion was in line with this interpretation.
This fact could possibly be explained by assuming that
the decrease in the specific radioactivity of uranium and
other radioactive isotopes is a consequence of low-energy
nuclear reactions. Below we call this hypothetical phe-
nomenon the low energy transformation of nuclei (here-
inafter LET [15]). Indeed, since the electric explosion of
a titanium foil in both distilled water [12,16,17] and ura-
nium salt resulted in depletion of the natural titanium
isotope mixture in 48Ti isotope, it is reasonable to assume
that this phenomenon is caused by the same physical
mechanism in both cases. The experimental research of
the regular features of LET that we have carried out for
many years showed that even-even isotopes of chemical
elements with atomic numbers divisible by  16 (А = 16
is oxygen) are more prone to be transformed than their
neighbors.
Yet another hypothetical mechanism responsible for
the uranium isotope distortion could be a change in
-decay periods caused by either ionization or action of
intense magnetic fields. The atomic electrons increase
the -decay probability with respect to that for a com-
pletely ionized atom. First, the field of atomic electrons
decreases the barrier for an -particle and, second, the
nuclear charge decreases by 2 units upon -decay, which
changes the electron shell energy. Taking account of the
effect of atomic electrons results in the necessity of re-
placing energy of an -particle in the calculation of the
-decay constant by an “effective” energy, which is
greater than the real energy 5
433
73 65EE ZZ eV
[18]. Due to the exponential dependence of the -decay
probability on the -particle energy 1
ln constpE

,
the effect of atomic electrons may be pronounced. As
was to be expected, the atomic electrons affect low-en-
ergy processes to a larger extent. For example, for 147Sm
(-particle energy ~ 2.31 MeV; T½ = 7  1011 years), the
presence of the electron shell increases the probability of
-decay 2.6-fold compared with the nucleus of a fully
ionized atom [18].
The influence of a superstrong magnetic field on the
-decay probability can be qualitatively described in the
following way. An external superstrong magnetic field
changes the energy of the atomic electron shell [19] and,
hence, changes also the energy of any nuclear decay, as
the decay energy is equal to the difference between the
total energies of the initial and final systems with allow-
ance for ionization energies of atoms or ions [1]. For
-decay, the presence of an external superstrong mag-
netic field results in an increase in the decay energy and,
hence, in an increase in the -decay probability. Since
the 238U -decay energy is lower than the energies of the
principal channels of 235U -decay, the relative increase
in the 238U -decay probability caused by ionization and
by the effect of an external superstrong magnetic field on
the atomic electron shell would be more pronounced than
that the relative increase in the 235U -decay probability.
On the other hand, an external magnetic field changes
the geometry of the problem: the spherical symmetry is
replaced by the preferential direction along the magnetic
field. This effect is ambiguous and would be considera-
bly different for the even-even 238U nucleus having a
zero magnetic moment and the 235U nucleus where the
-decay occurs between states of nuclei with nonzero
spins.
It can be seen without difficulty that since the above-
discussed effects have different signs with respect to the
change in the specific volume activity of isotopes, then
depending on the experimental conditions, either an in-
crease or a decrease in the resulting specific activity with
respect to different U isotopes is possible. This is actu-
ally observed in experiments.
One more reason supporting LET is the disturbance of
234Th secular equilibrium observed in experiments. The
disturbance of the equilibrium was due to a decrease in
the 234Th specific concentration in an uranyl solution.
This conclusion follows from data of  and -spec-
trometry. Indeed, if only the 238U specific concentration
decreased at the instant of electric explosion, then the
specific -activity of 234Th would decrease with the pe-
riod T = 24.5 days. However, the sharp drop of the spe-
cific -activity was detected during the first 24 hours
after the electric explosion. The same conclusion can be
drawn from the -intensity ratio of E = 92.5 keV lines of
the sample and the initial solution, which was
92.5 92.5
ex rs1II

. Thus, the sign of this effect and the fact
of the subsequent 234Th accumulation with time preclude
interpreting the disturbance of secular equilibrium as
being due to the decrease in the 238U concentration alone.
As has already been noted in the Introduction, the
macroscopic nature of the observed distortions of the
initial uranium isotope ratio implies that the phenomenon
responsible for this effect occurs in a solution volume
considerably exceeding the plasma channel volume. This
is evidence supporting the hypothesis that some radiation
arises during the electric explosion [12]. The detection of
pulses of obviously electromagnetic origin by gas detec-

L. I. URUTSKOEV ET AL.
234
tors is indirect evidence in favor of the electromagnetic
nature of the arising radiation.
It is noteworthy that very similar signals but in much
lower quantities were also detected in those experiments
with the organic-glass prechamber in which H2O, D2O or
aqueous glycerol were used instead of the uranyl solution.
Several recent publications reported the observation of
neutrons in high-voltage electrolysis in D2O or during
cavitation (e.g., [20]). In those cases where the neutron
spectrum was not directly measured and neutron detec-
tors were used in the counting mode, an error could arise
in the interpretation of the results of measurements due
to detection of “false” pulses.
The disturbance of the equilibrium between 234Th and
its daughter 234mPa nucleus detected by -spectrometry
can be a result of the change in the –-decay probabilities
along different channels. This item was discussed in
more detail previously [21].
Note that the specific features arising during the spec-
trometric measurements and observed during the first 24
hour after electric explosion (the “first measurement”
problem) coincide, as regards the time scale of the effect,
with the period for disappearance of the deformation of
57Fe Mössbauer spectrum noted previously [13]. Coinci-
dence of the time scales of these effects can suggest a
common origin.
Thus, summarizing the results of these studies pro-
vides the following conclusions. Additional evidence
supporting the emergence of lepton type “strange” radia-
tion at the instant of electric explosion of a conductor in
a liquid was obtained [12]. The electric explosion of tita-
nium foil in an uranium salt was shown to initiate a
number of phenomena with still obscure physical
mechanisms. It can be seen from the presented experi-
mental results that all the observed effects are closely
related to one another but the available experimental data
do not allow their final separation into constituents.
7. Acknowledgements
The authors wish to express their gratitude to staff
members of the Russian Scientific Center Kurchatov
Institute V. L. Kuznetsov and S. V. Zhukov for perform-
ing numerous measurements. We are grateful to RE-
KOM staff members and list the persons without whose
active participation it would be just impossible to per-
form the experiments: A. G. Volkovich, S. V. Smirnov,
A. A. Gulyaev, A. P. Govorun, P. F. Strashko, V. L.
Shevchenko, A. B. Gaverdovsky, and V. N. Bayushkin.
We thank A. A. Rukhadze for useful discussion and for
the support of these works.
The experiments were carried out at the RECOM (an
affiliate company of the I. V. Kurchatov Institute of
Atomic Energy) at the Kurchatov Institute territory since
2002-2004.
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