Keywords

5.1 Introduction

Several evidences of anomalous nuclear reactions occurring in condensed matter were observed by different authors [1–34]. These experiments are characterized by extra heat generation, neutron emission, and alpha particle detection. Some of these studies, using electrolytic devices, reported also significant evidences of compositional variation after the microcraking of the electrodes [35–40].

In most of these experiments, the generated heat was calculated to be several times the input energy, and the neutron emission rate, during electrolysis, was measured to be about three times the natural background level [6]. In 1998, Mizuno presented the results of the measurements conducted by means of neutron detectors and compositional analysis techniques related to different electrolytic experiments. According to Preparata, “despite the great amount of experimental results observed by a large number of scientists, a unified interpretation and theory of these phenomena has not been accepted and their comprehension still remains unsolved” [6–9, 26, 27]. On the other hand, as shown by most of the articles devoted to Cold Nuclear Fusion, one of the principal features is the appearance of microcracks on electrode surfaces after the tests [26, 27]. Such evidence might be directly correlated to hydrogen embrittlement of the material composing the metal electrodes (Pd, Ni, Fe, Ti, etc.). This phenomenon, well-known in Metallurgy and Fracture Mechanics, characterizes metals during forming or finishing operations [41]. In the present study, the host metal matrix (Pd and Ni) is subjected to mechanical damaging and fracturing due to hydrogen atoms penetrating into the lattice structure and forcing it, during the gas loading. Hydrogen effects are largely studied especially in metal alloys where the hydrogen absorption is particularly high. The hydrogen atoms generate an internal stress that lowers the fracture resistance of the metal, so that brittle crack growth can occur with a hydrogen partial pressure below 1 atm [41, 42]. Some experimental evidence shows that neutron emissions may be strictly correlated to fracture of non-radioactive or inert materials. From this point of view, anomalous nuclear emissions and heat generation had been verified during fracture in fissile materials [2–4] and in deuterated solids [5, 8, 30]. The experiments recently carried out by Carpinteri et al. [36–39] represent the first evidence of neutron emissions from piezonuclear fissions occurring during the failure of inert, stable, and non-radioactive solids under compression, as well as from non-radioactive liquids under ultrasound cavitation [37, 38]. In the present paper, we analyze neutron and alpha particle emissions during tests conducted on an electrolytic cell, where the electrolysis is obtained using Ni-Fe and Pd electrodes in aqueous potassium carbonate solution. Voltage, current intensity, solution conductivity, temperature, alpha and neutron emissions were monitored. The compositions of the electrodes were analyzed both before and after the tests. Strong evidences suggest that the so-called Cold Nuclear Fusion, interpreted under the light of hydrogen embrittlement, may be explained by piezonuclear fission reactions occurring in the host metal, rather than by nuclear fusions of hydrogen isotopes adsorbed in the lattice. These results give an important confirmation about the hypothesis proposed by the authors and reported in previous papers on electrolysis with Ni-Fe and Cr-Co electrodes [43, 44].

5.2 Experimental Set Up

Over the last 10 years, specific experiments have been conducted on an electrolytic reactor (owners: Mr. A. Goi et al.). The aim was to investigate whether the anomalous heat generation may be correlated to a new type of nuclear reactions during electrolysis phenomena. The reactor was built in order to be appropriately filled with a salt solution of water and Potassium Carbonate (K2CO3). The electrolytic phenomenon was obtained using two metal electrodes immersed in the aqueous solution. The solution container, named also reaction chamber in the following, is a cylinder-shaped element of 100 mm diameter, 150 mm high, and 5 mm thick. For the reaction chamber Inox AISI 316 L steel was used. The two metallic electrodes were connected to a source of direct current: a Ni-Fe-based electrode as the positive pole (anode), and a Pd-based electrode as the negative pole (cathode).

The reaction chamber base consists of a ceramic plate preventing the direct contact between liquid solution and Teflon lid. Two threaded holes host the electrodes, which are screwed to the bottom of the chamber successively filled with the solution. A valve at the top of the cell allows the vapor to escape from the reactor and condense in an external collector. Externally, two circular Inox steel flanges, fastened by means of four threaded ties, hold the Teflon layers. The inferior steel flange of the reactor is connected to four supports isolated from the ground by means of rubber-based material. As mentioned before, a direct current passes through the anode and the cathode electrodes, provided by a power circuit connected to the power grid through an electric socket. The components of the circuit are an isolating transformer, an electronic variable transformer (Variac), and a diode bridge linked in series.

Electric current and voltage probes were positioned in different parts of the circuit. The voltage measurements were performed by a differential voltage probe of 100 MHz with a maximum rated voltage of 1,400 V. The current was measured by a Fluke I 310S probe with a maximum rated current of 30 A. Current intensity and voltage measurements were also taken by means of a multimeter positioned at the input line. From the turning on to the switching off of the electrolytic cell, current and voltage were found to vary in a range from 3 to 5 A and from 20 to 120 V, respectively.

For an accurate neutron emission evaluation, a He3 proportional counter was employed (Xeram, France) with pre-amplification, amplification, and discrimination electronics directly connected to the detector tube. The detector is supplied by a high voltage power (about 1.3 kV) via NIM (Nuclear Instrument Module). The logic output producing the TTL (transistor–transistor logic) pulses is connected to a NIM counter. The logic output of the detector is enabled for analog signals exceeding 300 mV. This discrimination threshold is a consequence of the sensitivity of the He3 detector to the gamma rays ensuing neutron emission in ordinary nuclear processes. This value has been determined by measuring the analog signal of the detector by means of a Co-60 gamma source. The detector is also calibrated at the factory for the measurement of thermal neutrons; its sensitivity is 65 cps/nthermal (±10 % declared by the factory), i.e., the flux of thermal neutrons is one thermal neutron/s cm2, corresponding to a count rate of 65 cps. Finally, before and after the experiments, Energy Dispersive X-ray Spectroscopy has been performed in order to recognise possible direct evidence of piezonuclear reactions that can take place during the electrolysis. The elemental analyses were performed by a ZEISS Auriga field emission scanning electron microscope (FESEM) equipped with an Oxford INCA energy-dispersive X-ray detector (EDX) with a resolution of 124 eV @ MnKa. The energy used for the analyses was 18 KeV.

5.3 Neutron Emission Measurements

Neutron emission measurements performed during the experimental activity are represented in Fig. 5.1. The measurements performed by the He3 detector were conducted for a total time of about 24 h. The background level was measured for different time intervals before and after switching on the reaction chamber. These measurements reported an average neutron background of about (3.23 ± 1.49) × 10−2 cps. Furthermore, when the reaction chamber is active, it is possible to observe that, after a time interval of about 7.5 h (460 min), neutron emissions of about 3 times the background level may be detected. After 9 h (545 min) from the beginning of the measurements, it is possible to observe a neutron emission level of about one order of magnitude greater than the background level. Similar results were observed after 20 h (1,200 min) when neutron emissions up to 7 times the background were measured.

Fig. 5.1
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Neutron emission measurements. Emissions between 3 times and 10 times the background level have been observed during the experiment

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5.4 Compositional Analysis of the Pd Electrode

In the present section, the chemical compositions before and after the experiment will be taken into account, as well as the concentrations measured for each element identified on the surfaces of the two electrodes (see Tables 5.1 and 5.2).

Table 5.1 Element concentrations before and after the electrolysis (Pd electrode)
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Table 5.2 Element concentrations before and after the electrolysis (Ni-Fe electrode)
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In particular, under the light of what can be deduced from the neutron emissions measurements and according to the hydrogen embrittlement hypothesis suggested by Carpinteri et al. [43, 44], the presence of microcracks and macrocracks on the electrode surface (Fig. 5.2a, b, c) is accounted in the mechanical interpretation of the phenomena. These evidences are particularly strong in the case of the Pd electrode, where a macroscopic fracture took place during the test. The fracture presented a width of about 40 μm observable at naked eyes (see Fig. 5.2c).

Fig. 5.2
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Images (a, b, c) of the Palladium electrode surface: the fracture presented a width of about 40 μm and was observable at naked eyes

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Considering the average decrement of Pd (−28.6 %), reported in Table 5.1, a first and fundamental fission reaction can be assumed:

$$ {\mathrm{Pd}}_{46}^{106}\to {\mathrm{Ca}}_{20}^{40}+{\mathrm{Fe}}_{26}^{56}+10\kern0.5em \mathrm{neutrons} $$
(5.1)

According to reaction (5.1), the Pd decrement is counterbalanced by Ca and Fe increments by the following quantities: 10.8 and 15.1 %, for Ca and Fe, respectively. These variations may be accompanied by a neutron emissions corresponding to the remaining 2.7 % of the mass concentration (see also Figs. 5.3, 5.4, 5.5, and 5.6). The whole iron increment, according reaction (5.1), could be entirely considered as the starting element for the production of other elements. Hence, a second hypothesis can be proposed involving Fe as starting element and O as the product, together with alpha and neutron emissions:

Fig. 5.3
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Pd concentrations measured on 15 different points of the electrode surface, before (square) and after (triangle) the electrolysis; the average concentration M and the corresponding stand. dev. σ are reported

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Fig. 5.4
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Fe concentrations measured on the electrode surface after the electrolysis; Iron has not been detected before the experiment

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Fig. 5.5
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Traces of Ca concentrations have been detected after the electrolysis

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Fig. 5.6
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The presence of the oxygen is remarkable after the experiments

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$$ {\mathrm{Fe}}_{26}^{56}\to 3{\mathrm{O}}_8^{16}+{\mathrm{He}}_2^4+4\kern0.5em \mathrm{neutrons} $$
(5.2)

According to reaction (5.2), the iron depletion produces 12.9 % of oxygen with alpha particles (He) and neutron emissions. The total measured increment in oxygen after the experimental test is equal to 18.5 % (see Table 5.1). This quantity seems to be only partially explained by reaction (5.2). The remaining 5.6 % of O concentration could be explained considering other reactions involving Ca (product in reaction 5.1) as the starting element:

$$ {\mathrm{Ca}}_{20}^{40}\to {\mathrm{O}}_8^{16}+{\mathrm{Mg}}_{12}^{24} $$
(5.3)
$$ {\mathrm{Ca}}_{20}^{40}\to 2{\mathrm{O}}_8^{16}+4{\mathrm{H}}_1^1+4\kern0.5em \mathrm{neutrons} $$
(5.4)

From reaction (5.3), we can consider a decrease in Ca concentration of 1.6 % and the formation of 1.0 % of Mg and 0.6 % of O. On the other hand, from reaction (5.4), we obtain a decrease in Ca equal to 5.9 %. This decrease gives an increase of 4.7 % in O and 0.6 in H, with neutron emissions equal to 0.6 %.

Considering the O increases coming from reactions (5.2), (5.3), and (5.4), totally equal to 18.2 %, and the experimental evidence reporting a total measured O concentration of 18.5 %, we may assume that O seems to be almost perfectly justified by the proposed reactions. At the same time, the Mg increment observed after the experiment can be explained by the results of reaction (5.3), see also Table 5.1. According to reactions (5.3) and (5.4), the following balances may be considered: Ca (−1.6 %) = Mg (+1.0 %) + O (+0.6 %); Ca (−5.9 %) = O (+4.7 %) + H (+0.6 %) + neutrons (+0.6 %). Taking into account the same reactions, and considering the Ca increase coming from reaction (5.1) (10.8 %), a concentration of 3.3 % of Ca remains to be counterbalanced. To this purpose, it is possible to take into account additional reactions involving Ca as starting element and Si, K and C as the results:

$$ {\mathrm{Ca}}_{20}^{40}\to {\mathrm{K}}_{19}^{39}+{\mathrm{H}}_1^1, $$
(5.5)
$$ {\mathrm{C}\mathrm{a}}_{20}^{40}\to {\mathrm{C}}_6^{12}+{\mathrm{Si}}_{14}^{28}. $$
(5.6)

From these reactions, the following balances may be considered: Ca (−1.6 %) = Si (+1.1 %) + C (+0.5 %); Ca (−1.5 %) = K (+1.5 %). Finally, considering the formation of 0.2 % of Ca after the experiment, the total Ca increase assumed by reaction (5.1) may be perfectly matched. The total Ca increment is equal to 10.8 %, the total Ca decrement by reactions (5.3), (5.4), (5.5), and (5.6) is 10.6 %, which returns a 0.2 % Ca concentration as measured. With regards to iron, its experimental compositional increase, measured on the Pd electrode, could be partially interpreted as an electrochemical effect due to the Fe decreasing in the Ni electrode. Finally, as for the final average variations in Mg (1.0 %), Si (1.1 %), and K (1.5 %), the hypotheses are perfectly consistent with the measured values (see Table 5.1 and Figs. 5.7, 5.8, and 5.9).

Fig. 5.7
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The magnesium presence is evident after the experiment, while there was no trace of it before

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Fig. 5.8
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Potassium evidences have been detected only after the experiment

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Fig. 5.9
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EDS measures show evident traces of silicon only after electrolysis

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5.5 Nickel Electrode Composition Analysis

Let us consider the Nickel Electrode. Table 5.2 summarizes the concentration variations after the electrolysis. Nickel diminishes of 23.1 %, whereas the most apparent positive variation is that of oxygen (+19.5 %). It is worth noticing that the average concentration decrease in Fe (−2.0 %) is comparable to the average increase in Aluminum (+1.8 %). The Figs. 5.10, 5.11, 5.12, and 5.13 show the series of the concentrations measured before and after the experiment. In particular, when an element average concentration is zero, the corresponding series is absent: for instance, on the Ni electrode surfaces the Aluminum has not been detected before the electrolysis (Fig. 5.13).

Fig. 5.10
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Nickel electrode: the series of the Ni concentrations measured before and after 20 h of electrolysis are showed. An average variation between the two series of about 23.1 % may be considered

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Fig. 5.11
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O concentration before and after the experiment. The average values of O concentration change from a mass percentage of 2.0 % at the beginning of the experiment to 21.5 %

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Fig. 5.12
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Fe concentration before and after the experiment. The average values of Fe concentration change from a mass percentage of 0.4 % at the beginning of the experiment to 2.4 %

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Fig. 5.13
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Al concentration before and after the experiment. The average values of Al concentration (1.8 %) appear at the end of the test

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On the basis of the piezonuclear reaction conjecture, we could assume the oxygen average variation as a nuclear effect caused by the following hypothesis:

$$ {\mathrm{Ni}}_{28}^{59}\to 3{\mathrm{O}}_8^{16}+2{\mathrm{He}}_2^4+3\kern0.5em \mathrm{neutrons}. $$
(5.7)

A second hypothesis could be considered for the Al average variation, which could be consistent with the following:

$$ {\mathrm{Fe}}_{26}^{56}\to 2{\mathrm{Al}}_{13}^{27}+2\kern0.5em \mathrm{neutrons}. $$
(5.8)

A third hypothesis could be made considering the Silicon average variation:

$$ {\mathrm{Ni}}_{28}^{59}\to 2{\mathrm{Si}}_{14}^{28}+3\kern0.5em \mathrm{neutrons} $$
(5.9)

Reactions (5.7), (5.8), and (5.9) imply emissions of neutrons, which will provide a great support to the hypotheses based on piezonuclear reactions. The main idea underlying the hypothesis is that an average decrease of 23.1 % in Nickel underwent a reaction producing at least 18.8 % of oxygen together with alpha and neutron emissions. Secondly, an average depletion of 2 % in Fe would have produced about 1.8 % of Aluminum accompanied by neutron emissions. Thirdly, another average decrease in Ni of 1 % could have gone into Silicon (+0.9 %) and more neutrons. Considering the standard deviations corresponding to each average concentration measured before and after the experiment (Figs. 5.10, 5.11, 5.12, and 5.13), the three considerations outlined above could be summarized according to the following balances: (1) Ni (−23.1 %) ≈ O (+18.8 %) + Si (+0.9 %) + alpha + neutrons, and (2) Fe (−2.0 %) ≈ Al (+1.8 %) + neutrons. Except for the Potassium increment (+2.7 %), which could be explained considering the deposition of the salt contained in the solution. The variations of the other elements’ are lower than 1 %.

5.6 Conclusions

Neutron emissions up to one order of magnitude higher than the background level were observed during the operating time of an electrolytic cell. In particular, after a time span of about 7.5 h, neutron emissions of about 3 times the background level were measured. After 9 h and at the end of the test (after 20 h), it was possible to observe neutron emissions of about one order of magnitude greater than the background level.

By the EDX analysis performed on the two electrodes, significant compositional variations were recorded. In general, the decrements in Pd at the first electrode seem to be almost perfectly counterbalanced by the increments in lighter elements like oxygen. As far as the Ni-Fe electrode is concerned, the Ni decrement is almost perfectly counterbalanced by the O and Si increments according to reactions (5.7) and (5.9). At the same time, the Fe decrement may be considered to explain the final concentration of Al according to reaction (5.8). Chemical variations and energy emissions may be accounted for direct and indirect evidence of mechano-nuclear fission reactions correlated to microcrack formation and propagation due to hydrogen embrittlement. The so-called Cold Nuclear Fusion, interpreted under the light of hydrogen embrittlement, may be explained by piezonuclear fission reactions occurring in the host metal, rather than by nuclear fusion reactions of hydrogen isotopes forced into the metal lattice.