Duds
Duds ( technical language : old ordnance , non-detonated ordnance , explosive ordnance residues ) are ammunition such as grenades or bombs that have not exploded or not fully exploded after being used (firing or dropping). This can be caused by technical failure, incorrect operation, unfavorable operating conditions or sabotage during production. A dud is to be differentiated from a failure : While the ignition mechanism triggers a dud but does not lead to an explosion, in the case of a failure the ignition mechanism did not trigger or only partially.
Long-term detonators for aircraft bombs represent a special category , which should serve to maintain the threat potential in the target area in the long term and to let the bomb explode later. These detonators can also fail and become real duds. Bombs that do not explode but burst open on impact are known as smashers . Bombs that only partially respond to ignition are called partial toners .
The term is also used for non-detonating fireworks .
Internationally these are referred to as UXO as an abbreviation for Unexploded Ordnance (translated: "unexploded ammunition").
background
In Germany dud also provide more than 70 years after the end of the Second World War a serious problem. Especially in industrial and urban areas ( Ruhr area , Cologne , Hamburg , Dresden , Berlin , Oranienburg , Potsdam ), etc., the primary target of Allied air strikes were , a large number of duds can still be found in the ground today. These are often discovered independently of the specific search during construction work.
Experience from the explosive forces in World War II showed that around 10 to 20% of the bombs dropped by the Allied aircraft were duds. Since 1947 there have been around 20 self-detonations in Germany.
The Austrian Army states that around one percent of the grenades fired in Austria are duds.
causes
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The dud rate was particularly high for aircraft bombs from the Second World War. Due to the safety requirements for the own armed forces during transport, storage, loading and during the flight to the target, the bombs had to be secured in such a way that incidents, including crash landings and crashes, could not cause the bombs to detonate. It was only shortly before the start that the detonator was unlocked by pulling the pin. B. sharpened by a rotating wind turbine in the air stream . In this case alone, a multitude of causes could lead to the fact that the sharpening process did not or only incompletely and the bomb hit out of focus.
With the mechanical impact fuses, many influences could prevent the triggering of a fully armed bomb:
- Detonation of another explosive device in the immediate vicinity. Due to the force of its explosion, the explosive device did not hit the intended angle of impact.
- too soft serve z. B. when hitting muddy ground or buildings with an unfavorable ceiling construction, in which the falling body was braked with each breakthrough, but the necessary delay for the ignition is not achieved.
- Wall strike: A bomb seldom falls exactly vertically. If it hits a wall at an acute angle, it bounces off and also stumbles.
- Technical error in the detonator, especially in mass production.
- Sabotage : This mainly affects the German armaments industry, which in the Second World War used forced laborers in production to a large extent , who deliberately made non-working ammunition. But there are also reports of more or less successful infiltration of the enemy arms production with the same purpose. In doing so, attempts were sometimes made to sabotage the construction plans or production equipment in such a way that they would have led to bombs that were inoperable. The duds released in the process are considered particularly treacherous, as even the construction plans approved by the manufacturer after the war do not have to reliably correspond to the explosive device in question. The identification of the batch is of vital importance here.
- Special case of long-term detonators: With the aim of hindering extinguishing and rescue work or making it impossible and, as a result of the detonation, to hit people who had already left their protected rooms, even hours after the end of the air attack , chemical-mechanical long-term detonators were used with a delay time of 1 developed up to 144 hours (6 days). Externally is indistinguishable whether still running in a long time fuze of the triggering process (by dissolution of a celluloid plate by means of acetone , intended trip time up to 6 days after discharge), whether the release process was interrupted by unknown circumstances and may at any time start again or whether it is a real failure.
search
Historical aerial photographs taken by reconnaissance planes after a bombing are used today to search for impact funnels to document the success of the action. With partially automated image processing processes, concrete suspicion points of duds can be detected e.g. B. a building plot can be determined.
In contrast to mine hunting , in which small metal parts (mainly non-ferrous metal ) are tracked down with metal detectors , when searching for duds, one uses the fact that all bombs (grenades etc.) are made of ferromagnetic steel . This ferromagnetic steel causes a disturbance of the otherwise homogeneous earth's magnetic field on the earth's surface, which can be detected with the help of magnetometers . Most commonly, these magnetometers are used in a gradiometer arrangement. Two probes (magnetometers) are arranged in opposite directions at a distance of approx. 0.5 ... 2 m (base) so that they both measure the same induction of opposite polarity in a homogeneous field . If you connect these two probes in series, the effective measured value shows the difference (the gradient) of the magnetic field. In this way, bombs (depending on their size) can be located at depths of up to 6 m (in the overflow approx. 10 nT deflection).
For comparison: Metal detectors for mine hunting are optimized for the detection of minimal metal parts and have detection depths of a maximum of 50 cm. Occasionally, however, large loops are used that have a greater search depth (approx. 4 m).
The sensitivity of the gradiometers described varies greatly depending on the complexity of the design. In addition to a minimum noise level of the probes used, their parallelization is decisive. Since both probes are not perfectly parallel to each other, a movement / rotation in the earth's magnetic field of around 50,000 nT can easily produce a range of several nanotesla. High quality products guarantee a search sensitivity of a few nanotesla. This is associated with a complex mechanical parallelization of the two probes, which has to be readjusted from time to time.
An exception are so-called tension band probes, in which the probe cores are attached to a tension band that is under strong tension. These probes are maintenance-free and parallel with high precision (change when rotating in the earth's field <1 nT).
Elimination
Duds represent a great hazard potential. Combat areas, military training areas and areas on which ammunition was improperly destroyed have to be laboriously cleared of such dangerous remains, and bombed urban areas are still far from dud free.
The disposal of munitions in Germany today is largely carried out commercially. Responsibilities and implementation are regulated differently in the federal states in their own ordinances on the disposal of ordnance.
How a dud is defused depends on the location, the construction and the condition of the explosive device and detonator.
After the discovery, the country of origin and the exact type of dud and detonator are therefore determined first. The design features give rise to the risk of self-triggering (e.g. in the case of pre-tensioned detonators), the sensitivity to external influences (vibrations, changes in position, temperature influences, etc.).
Defusing at the site
Depending on the factors mentioned, the defusing , i. H. interruption of the ignition chain by removing the igniter. It is possible if the detonator can be clearly identified, is in good condition and its construction and the location of the explosive device allow it to be removed without significantly increased risk. Since there is always a residual risk, safety radii are regularly established during defusing - in accordance with the risk of a detonation - and people in the area are evacuated.
Particularly in the case of long-term detonators that are equipped with a removal lock to prevent the detonator from being disarmed before it is triggered (the detonator triggers immediately when unscrewing), defusing it is time-consuming, as these detonators require special procedures:
- Removal of the detonator by a hydraulic pulling device that pulls it out of the thread of the detonator mount without turning it (American long-term detonators)
- Sudden unscrewing of the mechanical part of the detonator by means of a pyrotechnically driven screw device (so-called rocket clamp ), so that the mechanical parts are briefly pressed together by the centrifugal forces and only trigger after unscrewing without hitting the detonator (British long-term detonators)
- Cut out the detonator using a milling cutter
- Cutting out the igniter using a water jet cutting process
- Remove the igniter socket including the igniter if it is not pinned
If possible, such procedures are carried out under security, i. H. carried out by means of remote-controlled devices and video observation. Nevertheless, manual work is always required directly on the bomb in any case, which is associated with considerable risk. After disarming, the dud is transportable and can be transported away for further dismantling and destruction. However, detailed information on how to proceed with defusing is usually not published. This is to prevent laypeople from getting the wrong impression that they can easily defuse them themselves.
Destruction at the site
This approach is taken when the parameters found do not allow safe disarming or if an explosion would not cause any major damage to the area. In the case of a find during the construction of the Allianz Arena in Munich , for example, destruction at the site was preferred to defusing, as the dud was in an almost free field - but right next to the A 9 . Since the shut-off rooms do not differ from those of a defusing in the event of destruction, the destruction was considered the safer and faster solution.
In this case, the complete detonation of the dud is usually caused by attaching a destruction charge directly. In order to reduce the air pressure wave, to dampen the noise and in particular to limit the scattering circle of the resulting splinters, the dud is covered with sand, stone-free soil, straw, bales of paper, etc. if possible.
In the case of bombs, the head or bottom with the detonator that cannot be defused can be separated from the rest of the bomb by remote-controlled cutting devices (saw, water jet cutter). The rest is then safely transported away and disposed of, so that only the part with the detonator and a small amount of explosives has to be blown up.
A special combination of defusing and blasting are so-called low-order blasting or explosive defusing. Here, with special explosives opening the dud and cutting off the fuse effected without the actual explosive charge of dud comes into effect. However, since the - unintentional - complete detonation of the dud has to be expected here, evacuation, protective measures, etc. must be planned in the same way as the blasting.
In very rare cases, the dud is detonated at the site. For example, on August 28, 2012, an American 500 lb bomb was detonated in Munich. It contained approx. 125 kg of explosives and was equipped with a long-term detonator. Bales of straw used for insulation enlarged the fireball and caused significant fire damage in the area.
If the detonator is damaged and detonated on site, the evacuation radius can be greater than 500 meters or up to 1000 meters.
Removal in armed condition
This route is only used in exceptional cases if the site of the discovery is defused (e.g. in the case of head detonators of bombs that have been compressed by impact) or an explosion (e.g. in ongoing production facilities in the chemical industry or if bombs are found directly on or under buildings) not possible. If possible, measures are taken to temporarily secure the detonator from the outside or to make it less sensitive. The dud is transported in a position that offers the lowest risk of triggering. The dud is transported to the nearest suitable place where it can be blown up.
Accidents
- On August 9, 1990 in Wetzlar, two defusers were killed and three other people were injured when an American "1000-pound SAP bomb" was defused with an M 125 long detonator.
- On July 17, 2003 in Salzburg (Austria), two defusers were killed and another seriously injured while an American GP 500 lb bomb was being defused with a M 124 long-life detonator.
- On June 1, 2010 there were three deaths in Göttingen due to the uncontrolled detonation of an American dud of the type "1000-pound SAP bomb" with a long-term detonator M 125 one hour before the planned defusing. Two other people were seriously injured and four were slightly injured.
Self-ignition
There are also cases of "compression ignition", e.g. B. because a failed long-term igniter triggers after 70 years. Example from 22./23. June 2019, when a dud exploded in a field in Limburg- Ahlbach .
Situation in individual countries
Belgium
During the First World War , positional battles ( positional warfare , trench warfare ) took place in Flanders for several years . The main combat zones (French zone rouge ) were plowed up several times by grenades; they are often still today in the state of a crater landscape: in the ground are numerous duds and countless metal splinters from the exploded grenades (as well as the bones of those who fell or were buried). Here, too, there are still numerous duds in the ground; even here spontaneous ignition occurs occasionally to this day. Parts of the site are under monument protection ; There are also remains of ordnance ( heavy metals , poison gas residues) in the ground.
Germany
extent
The ordnance is in Germany by authorities of the country made. In the air raids of the Allies on the territory of the German Reich in 1940 10,000 tons , 1941 30,000 tons, 1942 40,000 tons, 1943 120,000 tons, 1944 650,000 tons and 1945 500,000 tons of bombs of all calibres were dropped; of which a total of 135,000 to 270,000 tons are considered duds. The number of undiscovered duds was estimated at 100,000 in 2013. Every year around 5,500 duds are defused.
Cost issues
Consequential damage from deliberate explosions or unintentional explosions is only carried out by the federal government on land owned by the federal government, areas previously used by Allied troops or in the case of ammunition owned by the Reich. Damage on private property will not be compensated. Builders must carry out the precautionary examination of the building site for duds themselves. In the case of dud finds, state authorities carry out the risk assessment, evacuation is carried out by private companies, and removal and destruction are carried out by state authorities.
Switzerland
In small-scale Switzerland, the army has to repeatedly practice in areas that are otherwise publicly accessible. This mainly applies to alpine terrain (glaciers, scree slopes, mountain meadows), but also to the military training area in Thun , which is a popular local recreation area. After serious accidents with several deaths, the army leadership came under public pressure in 1983. They responded with large-scale cleanups of the Alps and mountain areas. In addition, the army command raised awareness among the population with information campaigns. In the modern era, the army also developed brochures and mobile phone apps that make it easier to identify and report duds. Finders of duds are asked not to touch the objects, to mark where they were found and to report the find either to the police , via their emergency number or directly to the armed forces' dud reporting center. The alpine protection organization Mountain Wilderness achieved that reports of objects that are obviously dangerous (e.g. the floor is intact) are rewarded with 100 francs again.
Allied bombs from World War II, on the other hand, are less of a problem, as such attacks were rare and localized.
Vietnam
In Vietnam there are still a total of 800,000 tons of land mines and duds from the Vietnam War . From 1975 to 2015, up to 100,000 people were injured in the explosion.
Currently, all 63 provinces and cities are contaminated with duds and landmines. The priority is mine clearance for the northern border provinces of Lạng Sơn , Hà Giang and the six central provinces of Nghe An, Ha Tinh, Quang Binh, Quang Tri, Thua Thien and Quang Ngai. There were 22,760 victims of landmines and duds there by 2010, of which 10,529 died and 12,231 were injured. For this purpose, "The National Action Plan for the Prevention and Combating of Unexploded ordnance and mines from 2010 to 2025" was prepared and published by the government in April 2010.
Other countries
Residual ammunition and mines can also be found in many other former or current theaters of war or combat rooms. Examples of this are ammunition finds on Spitsbergen from World War II.
metaphor
The term dud is colloquially used as an insult .
See also
- Black Shell
- Defuser (USBV)
- Evacuation in Frankfurt am Main on September 3, 2017
- Ordnance disposal
- Ordnance clearance service
- Loading
- Land mines
- failure
literature
- High Command of the Wehrmacht : Provision H. Dv. 412, L. Dv. 764, M. Dv. No. 872 - Removal of unexploded bombs from enemy aircraft bombs - 1939
- Michael Katzsch (Dissertation, 2009, TU Cottbus ): Methodology for the systematic assessment of dangers due to bomb blind men from the Second World War using the example of the city of Oranienburg [1] (216 pages, pdf) (There is a chair for contaminated sites at TU Cottbus; this has been vacant since March 2012.)
Web links
Footnotes
- ↑ Searching for bombs with forester's probe and spade. Badische Zeitung , accessed on September 24, 2010 .
- ↑ see also English Wikipedia
- ^ Keyword self-detonation
- ↑ http://ooe.orf.at/news/stories/2669094/ The grenade found was from the army, ORF.at, September 18, 2014.
- ↑ Interview with an employee of the ordnance clearance service Rhineland-Palatinate: http://www.trier-reporter.de/so-wie-ein-kfz-mechaniker-der-an-bremsen-schraubt/
- ↑ I'm not defusing it, I'm not tired of life. Die Welt , August 29, 2012, accessed October 8, 2017 .
- ↑ Duds in Munich could not be defused: US long-term detonators make even bomb experts desperate. Focus , August 29, 2012, accessed October 8, 2017 .
- ^ Eva-Maria Bast: The search for bombs is increasing. Interview with Ralf Vendel, head of the ordnance disposal service in Baden-Württemberg. In: Südkurier of May 21, 2015.
- ↑ Deadly dangers among us. Article on stern.de from June 2, 2010 (accessed August 7, 2010)
- ↑ Article ( Memento from February 19, 2014 in the Internet Archive ) in the Göttinger Tageblatt from June 1, 2010 (accessed on August 7, 2010)
- ^ Antje Buchholz: World War Bomb exploded in Limburg-Ahlbach . hessenschau.de. June 24, 2019. Accessed June 27, 2019.
- ^ The riddle of Limburg . Mirror online. June 24, 2019. Accessed June 27, 2019.
- ↑ Manuel Ruoff: It did n't always crash. In: Preußische Allgemeine Zeitung of December 14, 2013, p. 4.
- ↑ Norman Hanert: Hardly any liability in the event of detonations. In: Preußische Allgemeine Zeitung of December 14, 2013, p. 4.
- ↑ Almost every citizen can be affected. In: Preußische Allgemeine Zeitung of December 14, 2013, p. 4.
- ↑ Marc Tribelhorn: Duds in Switzerland: The death in the hiking paradise In: Neue Zürcher Zeitung of July 17, 2017
- ↑ https://www.vtg.admin.ch/de/service/fuer-sie/blindgaenger-melden.html
- ↑ Góp sức khắc phục hậu quả bom mìn sau chiến tranh . Government information portal, April 23, 2010. Retrieved December 15, 2017.
- ↑ " Chương trình hành động quốc gia khắc phục hậu quả bom, mìn sau chiến tranh giai đoạn 2010 - 2025. Electronic portal of the Ministry of Defense of Vietnam, 2011. Accessed December 15, 2017.
- ↑ tu-cottbus.de: Since March 31, 2012, the Chair of Contaminated Sites is no longer occupied. ( Memento from April 12, 2013 in the web archive archive.today )