Protection of important objects from underwater terrorism.
SHCHERBAKOV Grigory Nikolaevich, Doctor of Technical Sciences, Professor
SHLYKOV Yuri Alexandrovich, Candidate of Technical Sciences
BROVIN Andrey Valerievich, Candidate of Technical Sciences
Protection of important objects from underwater terrorism
This article considers the issues of protection of important and ecologically dangerous objects from underwater terrorism.
The 21st century is becoming the century of the fight against terrorism for mankind.
Recent events show that death can come from anywhere: from the air, as happened in the United States on September 11, 2001, from the ground (cars filled with explosives are a favorite weapon of terrorists), from the water (everyone remembers the incident with the American destroyer «Cowell» off the coast of Yemen, into which a boat filled with explosives crashed), and also from under the water.
Moreover, the underwater direction is today one of the most unprotected from a possible terrorist attack. Particularly dangerous are underwater combat swimmers, who are able to stealthily approach any object and strike it [1, 2]
It is believed that the first combat swimmers appeared in 1935 in the Italian Navy. Swimmer-saboteurs were widely used by the warring countries during World War II.
For example, on December 18, 1941, the Italians disabled two British battleships and sank a tanker. Already in 1956, at the height of the Cold War, the battleship Novorossiysk was blown up in Sevastopol Bay.
One of the possible hypotheses for its death, actively discussed in the media, is a secret sabotage by NATO combat swimmers.
Currently, the navies of a number of countries have well-equipped combat swimmers: the USA, Italy, France, Great Britain, etc. Underwater gear and special equipment can be purchased commercially. Potential terrorists can also take advantage of this.
Fig. 1. Scheme of protection of a land facility from
a terrorist threat from the water area
Fig. 2. Unmasking signs of underwater saboteurs
The main task of the facility security system is to cover them from all directions — both from land and from the adjacent water area. To do this, the existing system for protecting facilities from land must be supplemented by a water section that closes the boundaries of the land section in the aquatic environment that reach the water's edge, creating a single closed security contour around the facility.
In order to solve this problem, the security system must include:
- a set of means for detecting underwater terrorist saboteurs attempting to penetrate the protected area;
- a communication system;
- a control body, including a command post (CP), as well as a central control panel for technical security equipment;
- a set of means for neutralizing detected underwater intruders;
- maneuvering forces (a boat for inspecting the water area and delivering a capture group to the location of identified violators).
The command post communicates and exchanges information with the command, as well as with other local interacting systems.
The main signs of a threat of attack by underwater terrorist saboteurs may be:
- activation of signal devices, detection of damage in special barriers;
- detection of traces of the landing of terrorist saboteurs on the shore;
- detection of foreign vessels, aircraft, helicopters, floating craft, etc., which may be classified as potential carriers of underwater terrorist saboteurs;
- detection of terrorist saboteurs underwater or on the surface, as well as on the shore;
- detection of caches of weapons and equipment, electronic reconnaissance equipment or navigation equipment in the water or on the shore near the protected facility.
Fig. 1 shows a possible variant of the scheme of protection of a land object from a terrorist threat from the water area. The water protection area, shaded in Fig. 1, contains various means of detecting an underwater intruder and actively influencing it. When moving in water, an underwater saboteur has a number of unmasking features (Fig. 2), which can be used to detect him.
The operation of detection means is based on various methods (Fig. 3). Possible methods of non-lethal (deterrent) and damaging effects on the intruder are shown in Fig. 4.
The most important subsystem in the object protection system is the detection subsystem. The remaining subsystems (neutralization, communication, warning and control) are activated, as a rule, after receiving data on the detection of terrorist saboteurs.
Unlike other subsystems, the detection subsystem must function continuously. This places increased demands on its reliability. Based on the available information, it follows that the basis of the underwater terrorist saboteur detection subsystem is stationary hydroacoustic detection equipment. The subsystem itself must be built in layers, which provides for the formation of successive detection lines as the saboteurs approach the protected object and directly at the shore.
The range of technical means for detecting individual underwater intruders based on different methods (Fig. 3) can be very different. For example, for magnetometric and quasi-stationary electromagnetic means it is, as a rule, a few meters. For hydroacoustic means (GAS) it reaches tens — hundreds of meters. However, the operation of GAS near the shore, especially in shallow water, is highly susceptible to various interference (surf noise, reflections from bottom irregularities, etc.). Increasing the noise immunity of GAS in these conditions requires solving a number of complex technical problems.
Underwater terrorist saboteurs can move underwater using either flippers or special carriers. The carriers contain working mechanisms and a propeller, while being the source of the primary hydroacoustic field. Therefore, it is possible to detect them using noise direction finders (passive hydroacoustic means). At the same time, the use of underwater carriers by saboteurs is unlikely due to their strong unmasking properties. The detection subsystem should also include a coastal radar station of the millimeter-centimeter range.
Its purpose is use as a stationary radar post, providing:
- monitoring the surface situation near the protected object;
- detection of surface objects, determination of their coordinates and movement parameters;
- recognition of surface objects.
The operating range should be approximately:
- detection of the swimmer's (diver's) head above the water surface 1 — 1.5 km;
- man on ice — 3 km;
- small vessels — 10 km.
Currently, the main real method of countering underwater terrorism is grenade throwing [3]. To protect ships, objects, ports and coastal structures from combat swimmers, Russia uses the well-known hand-held anti-sabotage grenade launcher DP-64, the small-sized controlled grenade launcher complex DP-65 and the multi-barrel rocket launcher MRG-1. But the use of these means is far from always possible, especially in peacetime near the coastline. In special cases, specially equipped combat swimmers are used to combat underwater saboteurs — near the protected object.
Fig. 3. Basic methods of detecting
underwater saboteurs in water
Fig. 4. Methods of influence
on an underwater intruder
One of the promising methods of active influence on an underwater intruder is the use of water electrolytic barriers (WEB) [4]. In a certain section of the aquatic environment, they make it difficult for the intruder to overcome the water line or make it impossible. The creation and use of such means is complicated by the lack of a regulatory framework governing the use of WEB in water to influence the intruder. Therefore, water electrolytic barriers are means that are under development.
For an intruder without special means of protection from the impact of the electric field of the current in the water, they are an effective means. It is possible to operate barriers in repelling and damaging modes. However, all of them have one significant drawback — a significant decrease in efficiency when the intruder uses special means of protection from the electric field of the current in the water — insulating and shielding wetsuits.
To increase the effectiveness of the impact on the intruder of the electric field of the current in the water created by the VES, technical solutions are provided that make it possible to combine them with barriers that allow mechanical damage to the protective equipment and thereby reduce the effectiveness of their protection.
One of the disadvantages of water electric barriers is their increased energy consumption, especially in sea water, which has high electrical conductivity.
However, when working near hydroelectric or nuclear power plants, this is not significant.
It has been shown previously [3] that the effect of electrohydraulic shock can be used to protect objects from the water area. At the same time, it should be noted that both in our country and abroad there are no specific engineering methods that would allow the creation of such installations for protecting water areas.
Although this effect has been used in industry for over 50 years, the equipment created is still exclusive («one-off»), developed for a specific technological task (stamping of metal products, cleaning from scale, etc.), all processes are described for small volumes (up to several cubic meters). There is still much that is unclear in the physics of the effect itself. Scientific discussions are still ongoing. The available information is, in fact, «vague» research, and not clear engineering and design. Specific information on the use of electrohydraulic shock to affect biological objects (combat swimmers, dolphins, etc.) is missing. Therefore, this direction is to a certain extent pioneering.
Fig. 5. Dependence of the range of action of the EGU
on a light diver in water on the type of impact
(preliminary theoretical assessment)
Fig. 6. Using EGU to protect the water pipeline of a nuclear power plant, hydroelectric power station
This complicates the rapid practical implementation of the electrohydraulic strike method in technical means of active protection from the water area.
At the same time, it should be noted that there are no fundamental technical prohibitions on the creation of such means — given the current state of high-voltage electrical equipment (pulse capacitors, arresters, etc.).
The energy required in our case should be approximately from units to several hundred kJ. Fig. 5 shows theoretical dependencies that allow us to estimate the range of impact on a lightweight diver (in normal equipment) depending on the required nature of the impact and the amount of energy of the pulse capacitors of the electrohydraulic unit (EHU).
When obtaining these estimated dependencies, the well-known Cole formula was used to calculate the pressure at the shock wave front in water during the explosion of a TNT charge.
Using this formula, as well as the known average value of the specific energy of explosive transformation for TNT:
Q0 = 4.2×106 J/kg [6, 7], we obtain an expression that allows us to approximately estimate the pressure at the shock wave front in water created by the EGU:
where C is the capacity of the capacitor bank, F; U is the voltage on the capacitors, V; h is the coefficient of conversion of the electrical energy of the discharge into the mechanical energy of the shock wave (0 As is known, the mechanical energy of an electric explosion in water most often reaches only about 25% of the electrical energy accumulated in the capacitors of the EGU. This figure was used in calculating the estimated dependencies in Fig. 5, from which it is clear that even with a very small energy of the capacitor (1 kJ), the range of combat impact on a light diver in water is up to 10 m. At high energies, the range increases accordingly. The mass of existing serial high-voltage capacitors will be from several tens to several hundred kilograms. In the future, we should expect a decrease in their mass. Moreover, the mass of capacitors is up to 60 — 70% of the mass of the entire high-voltage pulse generator. A possible version of the practical implementation of the EGU is shown in Fig. 6. The main task in further research will be the optimization of all EGU elements, and first of all, shock wave emitters in the aquatic environment. It is necessary to increase their electromechanical efficiency. The creation of directional shock wave emitters in fresh and sea water is also possible. Since the protected objects on the sea coast or inland waters are stationary or temporarily stationary (floating nuclear power plants, floating berths, etc.), the weight and size characteristics of the EGU do not have a great impact on their use. Therefore, at present there are technical possibilities for the practical implementation of the electrohydraulic strike method for combating intruders in the water. The relevance of the problem of protecting important land-based objects from underwater terrorism from adjacent waters is obvious. In terms of importance, this issue is comparable to protection from land and air terrorism, discussed in other publications of the Special Equipment magazine. And in this case, the seriousness and complexity of approaches to this problem are due to the need to solve several interrelated issues: However, all these costs will be insignificant compared to the losses in the event of a «successful» terrorist attack on an important facility (hydroelectric power station, nuclear power station, etc.), taking into account the enormous negative consequences in the economic and political spheres. Source: magazine «Special Equipment» No. 2 2008
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