Residual risk

The title of this article is ambiguous. Further meanings are listed under residual risk (definition of terms ) .

Under residual risk ( English residual risk ) is the process despite all made technical , procedural and economic risk mitigation remaining risk of a technical system , one event , system or other asset .

General

Risks are omnipresent in everyday life. Your risk takers ( private individuals , companies , the state and its subdivisions) must first recognize these risks within the framework of risk perception and subject them to a risk analysis in order to then confront them with their goals ( personal goals for private individuals, corporate goals for companies and national goals for states) . If the risks are too high in relation to the goals, the risk takers have to deal with the risks . This is done specifically through risk avoidance , risk reduction , risk compensation , risk diversification , risk transfer or risk provisioning .

If these measures are not intended to completely eliminate the existing risk, the marginal risk remains . Limit risk is the generally accepted dangers of a technical condition , event or process . Necessary risk management leads to the marginal risk, further risk management to the residual risk. The residual risk is therefore always smaller than the marginal risk. If, on the other hand, the existing risk is greater than the acceptable limit risk, there is a danger .

history

The term originally came from the nuclear industry . As a residual risk of nuclear power plants was formerly called the risk of the most serious about design basis accident beyond nuclear accident . In 1976, all risks of serious nuclear accidents with a probability of 10 ⁻⁴ per year were regarded as the residual risk . Residual risk from a technical perspective, the probability of occurrence of events with tolerable damage and of unknown events, from a social science perspective as reasonably be regarded probability of damage with a reasonable amount of damages and from legal point of view the risk does not oblige the state to protective measures.

With the reactor accident at the Three Mile Island nuclear power plant in March 1979 and the Chernobyl nuclear disaster in April 1986, the thesis of the relative harmlessness of the residual risk collapsed. The negatively connoted words Störfall , GAU or Super-GAU were later euphemistically replaced by residual risk.

During the series of accidents at the nuclear power plant Fukushima I as a result of the Tohoku earthquake in March 2011 took over the Federal Government , the "residual risk" as a reason for a moratorium on the life extension of German nuclear power plants , it whereas this, according to the of the Nuclear Society published the International Journal for Nuclear Power not was a residual risk, but an incorrect, insufficient design of the systems against tsunamis. The event in Fukushima led to a changed perception of the residual risk in public opinion and in the federal government , although such an event is actually inconceivable in Germany. The aim of the legislature to eliminate the residual risk that is unavoidable with the use of nuclear energy as quickly and as largely as possible - even if it should be based solely on a political reassessment of the willingness to accept this residual risk - by the Federal Constitutional Court (BVerfG) in December 2016 Not criticized.

Conceptual content

The content of the term “residual risk” is not defined uniformly in the specialist literature . For example, it is discussed whether residual risks should always be unknown according to the state of the art or the state of science . Unknown risks are not even recognized in risk perception and consequently cannot be classified as residual risks. With regard to the residual risk of technical systems, the citizen has to bear this as a “socially adequate burden” if it can be practically ruled out according to the state of the art in science and technology. It is incumbent on the legislature and the executive to take the precautionary measures to be taken and to define the demarcation between acceptable and unacceptable risks through judgmental decisions based on reasonableness .

How the legislature deals with the residual risk is shown in Section 11 (1) No. 4 GenTG , according to which the approval for the construction and operation of a genetic engineering facility depends, among other things, on the state-of-the-art science and technology for the required security level Facilities are available and precautions are in place and therefore no harmful effects on legal interests are to be expected. In § 5 para. 1 no. 2 BimSchG a residual risk limit is defined, below the emissions are allowed and adverse environmental effects have to be accepted as a residual risk.

In occupational safety , a hazard that cannot be excluded by technical measures is referred to as residual risk. The EN ISO 12100 defines the residual risk as "the risk remaining after protective measures have been taken". It consists of an estimable and an unknown part.

The BVerfG also uses the term residual risk, which according to Section 7 (2) No. 3 AtG should be taken into account when approving a nuclear facility. According to this, among other things, approval may only be granted if the necessary precautions against damage caused by the construction and operation of the system according to the state of the art in science and technology have been taken. This provision therefore accepts a residual risk. From a constitutional point of view, according to the BVerfG, the law (only) precludes approval if the construction or operation of the facility leads to damage that is a violation of fundamental rights .

Non-Obvious Risks in Safe Products

Residual risk is a risk that, despite its inherently safe construction and technical protective equipment, represents an unavoidable risk that is not obvious due to the use of a product . DIN 31000, DIN 820-120, EN ISO 12100-1 and the EC Machinery Directive 2006/42 / EC require manufacturers to implement a three-stage safety strategy for placing safe products on the market in the order listed:

1. Construct inherently safe.
2. If there are still unavoidable residual dangers: Provide protective devices.
3. If there are still unavoidable residual dangers afterwards: Warn users of these residual dangers (instructions, familiarization instructions, staff training, recommendation of personal protective equipment , PPE).

An operating manual must therefore not warn of dangers that can be eliminated constructively in advance. These must be eliminated. However, an operating manual must warn of remaining dangers.

Accordingly, manufacturers are not allowed to gloss over defective products in the instructions, because the manufacturer's responsibility ends and the user's responsibility begins with the instructions. They must protect themselves from residual dangers by observing the warnings in the instructions and, for example, providing or using recommended personal protective equipment.

Human factor

The “human factor” harbors a risk that is difficult to calculate. In addition to the possible deliberate exploitation of a technical danger by individual perpetrators, unintentional human errors due to insufficient care cannot be ruled out. Operating errors caused both the partial meltdown at the Three Mile Island nuclear power plant (1979) and the Chernobyl disaster (1986). The coincidence of two factors - incorrect connection of a pneumatic control and the "forgetting" to open valves after a test - was enough to cause this. Modern safety-relevant projects such as the European Ariane launcher program recognize the human factor as a quantifiable variable. One of the basic documents called "Human Error" ( German  "human error" ) and is the basis for all risk analyzes.

Kalkar judgment

The Federal Constitutional Court (BVerfG) arrived at a differentiated content in the so-called "Kalkar judgment" of August 8, 1978. In guiding principle 6, the court spoke of “hypothetical risks which, according to the state of the art, are unknown but cannot be excluded”. With regard to its duty to protect, the legislature should demand a regulation that with absolute certainty excludes any threats to fundamental rights that may arise from the approval of technical systems and their operation, would mean misunderstanding the limits of human cognitive ability and would largely prevent any state approval of the use of technology to ban. For the design of the social order, it must be based on estimates based on practical reason. Uncertainties beyond this threshold of practical reason are inescapable and insofar as socially adequate burdens to be borne by all citizens. This means that everything that lies within the “limits of human cognition” does not fall under the concept of residual risk.

economic aspects

A nuclear power plant will not change its residual risk due to an earthquake , only the known share of this risk is higher after the recalculation. Such a recalculation takes place in Switzerland after every flood ; an event classified as 100 years could just as easily be 50 or 200 years. Over time, experience with a system often grows in line with the experience curve . This changes the division between the known and the unknown part of the risk.

Damage assessment

When creating a risk analysis / probabilistic safety analysis for a process plant, one estimates the probability of occurrence of events, lists their possible consequences and presents remedial measures . An example of a very unlikely event, the consequences of which can be extremely large and for which remedial measures are in principle impossible, is one Core meltdown of a nuclear reactor with leakage of radioactive substances.

Since the severity and probability of damage are very low in many areas, a limit risk is specified for most activities, methods, procedures or (technical) processes (economically justifiable risks). Since the state of the science is technically not always realize it, the formulation used for particularly safety-critical process state of science and technology (technically conceivable precautions) and dangerous at less method, the formulation art (technically feasible precautions). The predominant use of the term residual risk in nuclear technology also shows that it is a young term for which the statistical relevance required for determining probabilities cannot always be used.

A residual risk is only economically justifiable if all risk management and risk reduction measures have been taken beforehand. If the risk assessment shows that the remaining residual risk is greater than the greatest justifiable limit risk, a further risk reduction must be carried out. If the existing risk is greater than the limit risk , there is a risk : ${\displaystyle R_{e}}$ ${\displaystyle R_{G}}$ ${\displaystyle G}$

${\displaystyle G=R_{e}>R_{G}}$,

Security is accordingly in place, if ${\displaystyle S}$

${\displaystyle S=R_{e}<R_{G}}$.

Technically and economically, security only begins below the limit risk and is highest when there is no longer any risk.

The systematic risk in finance is a typical residual risk because it can no longer be eliminated through risk diversification , even with an optimal mix of the individual values in the portfolio ( loan portfolio , securities portfolio ) .

literature

• Literature on residual risk in the catalog of the German National Library

Individual evidence

1. ↑ Norbert Hochheimer, Das kleine QM-Lexikon , 2011, p. 105
2. ↑ Konrad Reif, Automobilelektronik , 2009, p. 260
3. ^ Walter Geiger / Willi Kotte, Handbuch Qualität , 1986, p. 127
4. ↑ Heinz Olenik / Karl-Heinz Malzahn, Safety lighting systems , 1998, p. 1
5. ↑ Atomwirtschaft vol. 21, 1976, p. 253
6. ↑ Journal for Environmental Policy vol. 4, 1980, p. 910
7. ↑ Gerhard Strauss / Ulrike Hass / Ulrike Hass-Zumkehr / Gisela Harras, Brisante Words from Agitation to Zeitgeist , 1989, p. 517 ff.
8. ↑ Gerhard Strauss / Ulrike Hass / Ulrike Hass-Zumkehr / Gisela Harras, Brisante Words from Agitation to Zeitgeist , 1989, p. 517
9. ↑ tagesschau.de March 14, 2011 ( Memento from March 16, 2011 in the Internet Archive )
10. ↑ : Bernhard Kuczera, The severe Tohoku Seaquake in Japan and the effects on the Fukushima-Daiichi nuclear power plant ( Memento of the original from December 9, 2011 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. , International magazine for nuclear energy, special edition from volume 56, 2011, p. 8 
11. ↑ BVerfG, judgment of 6 December 2016, Az .: 1 BvR 2821/11 (including) = BVerfGE 143, 246
12. ↑ so the BVerfG in the "Kalkar judgment": BVerfGE 49, 89 , 143
13. ↑ Florian Rudolf-Miklau, dealing with natural disasters , 2018, p. 31
14. ↑ Michael Brenner / Anja Nehrig, The Risk in Public Law , in: The Public Administration (DÖV), 2003, p. 1025
15. ↑ DIN EN ISO 12100 Safety of machines - General principles for design - Risk assessment and risk reduction (ISO 12100: 2010); German version EN ISO 12100: 2010.
16. ↑ For example in a high-security laboratory during the anthrax attacks in September 2001 or the deliberate crash on Germanwings flight 9525 in March 2015
17. ↑ BVerfGE 49, 89 ff.
18. ↑ The probability of a flood increases with every event. ( Memento of the original from March 30, 2013 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. (PDF file; 131 kB) 
19. ↑ Page no longer available , search in web archives: flood classification statistical change after an event; Findings point 2.7
20. ↑ Gerald Zickert, electrical construction , 2019, o. P.

Please note the information on legal issues!