|| mas mtec / mttde fs15 technical risk management chapter 17, group theta 13.05.2015group theta: a....

||MAS MTEC / MTTDE FS15 Group Theta: A. Schamberger, R. Rohner, J. Ratia Garcia, G.-L. Morandi, A. Mettler

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Technical Risk Management

Chapter 17, Group Theta

13.05.2015


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1. Construction Failures

2. Nuclear Disasters

3. Engineering Approach to Risk

4. Technical Risk Theory

5. Limitations of the Technical Risk Approach

6. ISO Certification, Changes in 2015

7. Summary

8. Q&A

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Agenda


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The Hyatt Regency Hotel (USA 1981) walkways suspended from ceiling failure during dance competition killing 114 people and injuring 200

What happened? actual construction was modified

compared with the original design beam on the upper floor carried far

more load (force flow ) welded joint connection

Investigation results lack of communication

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Construction Failures

original design as built design


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Indoor Swimming Pool Uster (CH 1985) concrete ceiling suspended underneath

the roof with 207 chrome nickel steel bars failure during opening hours

What happened? stress corrosion cracking of bars after 13y shock to the corrosion science community

Investigation results bars corroded in the high chlorine

concentration environment of the swimming pool

Construction Failures


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A brief history

1. Fukushima (Japan 2011)

2. Chernobyl (former UdSSR 1986)

3. Three Mile Island (USA 1979)

What happened?

4. ▪ Tsunami floated backup diesel generators, crippling the reactor cooling systems

▪ Overheating led to hydrogen explosions and to radiation releases

5. ▪ Reactor systems test resulted in an explosion and fire ▪ Massive radiation release across western Soviet Union and Europe

6. ▪ Partial meltdown with “only” small radioactive releases▪ Failures in the non-nuclear secondary system,

followed by a human-operated relief valve in the primary system

Nuclear Disasters


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Nuclear technology Today’s boiling water reactors adapted from submarines,

because only technology that was field-tested Safer designs exist, but billions needed to test them

Safety management Backup systems to cool the core of the reactor Risk Assessment by Rasmussen 1975 (probability of system failing)

once every 20’000 years of operating time

Three Mile Island happened after 5 years of operating time In the 1980s technical risk management was questioned and

public discussion started Today old systems are ramped up to newest safety levels

(no efficiency increase) e.g. Beznau II (1.4 bCHF, 2010)

Nuclear Disasters


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Technical Risk Management

Accidents with new materials mayhappen years after construction

How safe is safe enough?

Construction failures are not uncommon, unfortunately.


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Quantitative estimate a cost

BUT How to quantify? How to deal with very

improbable but severe events?

0 ∙ = ?13.05.2015

Engineering Approach to Risk

Risk = Probability ∙ Impact

Impact

Probability

∞

e.g. predetermined

breaking points

e.g. restric

ted

a

ccess

Qualitative set priorities Often used Standards (ISO 12100, Machine

directive…)


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Quantification of impact Responsibility

Manufacturer, end user, society, government

Events to consider Technical failures, wrong usage, force

majeure

Acceptance Evaluation

Very difficult as soon as injuries/fatalities are included

Quickly becomes an ideological, ethical or political discussion

Difficult Quantification of Failure Impact

?

Where would you put the plant Fukushima?


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Technical Risk Theory: Failure rate Probability that failure occurs

Bathtub curve Three distinct phases in the lifecycle

of a product

Goal: increase the time span of constant failure rate predictability

Attention: Effect of environment not considered Systems not behaving according to it

• 40% expected to fail within 5 years

• 93’000 patients• $ 4 bio


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Reliability The probability that a device will perform its intended function during a

specified period of time under stated conditions

Assumptions and simplifications Failure rate is constant middle part of bathtub Reliability of system = Product of reliability of its all components Failure types are independent and lead to failure of system

Safety measure of the absence of

failures or conditions that would render the system dangerous

Reliability measure of the rate of failures

that render the system unusable


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Mean Time Between Failures (MTBF) Average time between two failures

Quantifies reliability

Depends on the definition ofa system failure

Assumption: independent failure types a system’s MTBF is calculated with the component’s MTBF


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Interdependence of the Shown Values Failure rate h(t) (bathtub curve) is constant

h

For constant failure rate, the reliability R(t) becomes

R(t) = e-h∙t

MTBF = 1/h

E.g. MTBF of a component is 1’500’000 hours,

what's the probability that any

such component reaches its MTBF?

h = 1/MTBF = 1/1’500’000

Probability not to fail until MTBF = R(t=MTBF) = e-1/MTBF∙MTBF

R = e-1 = 0.368 Only a third reaches it’s MTBF!


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Limitations of the Technical Risk Approach Three technical problems:

It assumes the worst case scenario

Real measurements take time (You should test the components until failure)

It is not really the “worst case” as it assumes independent components

Objections to the MTBF concept: It does not considers side-effects

Perception, acceptance and distribution of risks are not addressed

Human raction not considered

reaction to perceived risk

non-linearities

However, the methodologies within technical risk theory provide powerful tools and thus allow to design reliability into systems.


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ISO 9001 Certification

- ISO 9001 sets out the criteria for a QMS

- Can be used by any organization, regardless of its field of activity

- Implemented by over 1Mio. organizations in over 170 countries

- Brings many business benefits: consistent, good quality of products & services certified products are respected and recognised worldwide processes are optimized and sustainable

- Last version (ISO 9001:2008) is updated end 2015

- 3 year transition period after the revision


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ISO 9001:2015

What are the biggest changes so far:

Create high level structure: Risk Management Change Management Knowledge Management

What the changes mean for users: Risk-based Thinking (§6.1) Outsourcing: equality between „external provided goods“ and

„external provided services“ (§8.4)


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ISO 9001:2015

Dealing with risks: organizations must identify risks

that may affect product and process goals.

The company has to: (§6.1)

plan measures to counter these riskstake actions to address risks and opportunitiesevaluate the effectivenessprevent or reduce undesired effectsachieve continual improvement

Options to address risks can include: (§6.1.2)

avoiding risktaking risk in order to pursue an opportunityeliminating the risk sourcechanging the likelihood or consequences

Source: Draft ISO 9001:2015


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Success Factors for Risk Management

1. Simple method

The method for risk analysis has to be simple and standardized.

Depth risk analysis only if it brings a considerable added value.

2. Clear individual benefits

For each project team member must be visible, which individual benefit he gets from the risk management.

3. Open risk culture

Encourage all employees to contribute to risk identification and bring to light undesired effects.


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Thank you for your attention.

13.05.2015

|| mas mtec / mttde fs15 technical risk management chapter 17, group theta 13.05.2015group theta: a....

Documents

group theta

ratia garcia

technical risk approach

technical risk theory

s technical risk management

mettler1 slide

reactor risk assessment

built design slide