Nuclear Safety, Culture and Behaviours Nuclear Supply Chain Event 28 th April Mark Edmiston Head of EHSS&Q

Transcription

1 Nuclear Safety, Culture and Behaviours Nuclear Supply Chain Event 28 th April 2016 Mark Edmiston Head of EHSS&Q

2 Part 1 Nuclear Safety -Objectives To give Attendees an appreciation of: What nuclear safety is and how it is different from other types of safety The over-riding importance of nuclear safety and the consequences of poor nuclear safety Management of nuclear safety and how individuals can contribute

3 Why do we need an awareness of nuclear safety? Nuclear safety is of paramount importance to nuclear operators Everyone has the ability to influence nuclear safety by the actions they takeand the decisions they make

4 What is nuclear safety? How it differs Why is it important? Consequences of poor nuclear safety Managing nuclear safety. Individual contribution

5 International Atomic Energy Agency Nuclear Safety is : The achievement of proper operating conditions, prevention of accidents or mitigation of accident consequences, resulting in protection of workers, the public and the environment from undue radiation hazards. Another way of saying it is Nuclear safety is: About ensuring that the nuclear material is controlled: Prevent the likelihood of an unplanned nuclear reaction It remains contained where it is supposed to be Where appropriate it remains cooled We know where all the inventory is at any point in time.

6 Nuclear safety is about the control of nuclear material Radiological safety is about controlling exposure to that material

7 What is nuclear safety? How it differs Why is it important? Consequences of poor nuclear safety Managing nuclear safety. Individual contribution

8 Nuclear Materials. Have radioactive properties which can pose a hazard to people and the environment if they are not managed properly In the wrong circumstances can create dangerous reactions Such properties generate a variety of hazards which we must consider when we are working with them. Examples of nuclear materials include Plutonium, Uranium, Americium and Thorium.

9 How do nuclear operators view nuclear safety? Sellafield Ltd Nuclear Safety Policy extract: Nuclear Safety is our number one priority. We shall ensure the protection of workers, the public and the environment from undue radiological hazard by achieving and maintaining appropriate operating conditions, preventing accidents and mitigating accident consequences. Sellafield Ltd will achieve this high standard of Nuclear Safety performance through a systematic approach that develops nuclear safety culture, improves behaviours; effectiveness of processes; understanding of performance expectations and continuously reinforces standards and values.

10 Major Nuclear Safety Hazards Unplanned criticality Degradation of containment Major release of activity

11 Unplanned criticality Controlled criticalities occur inside nuclear reactors. They occur when sufficient nuclear material is in one place and is under the right conditions. Each fission of an atom produces a neutron that in turn strikes another atom causing another fission; this causes the chain reaction to become selfsustaining. An unplanned criticality occurs when the same reaction is achieved unintentionally and in an unsafe environment. It is dangerous and frequently lethal to humans within the immediate area.

12 Unplanned Criticality : JCO Tokaimura 1999

13 On 30 September 1999 a criticality accident occurred in an uranium reprocessing facility operated by JCO in Tokiamura. It resulted in the death of two workers. What happened Three workers preparing a small batch of fuel for an experimental reactor Prior to the event they were pouring uranium solution from a bucket into a precipitation tank At around 10:35 a.m. the criticality occurred and began to emit intense radiation One operator had his body draped over the tank while another stood nearby. Third was sitting at a desk four meters away All three technicians observed a blue flash and radiation alarms sounded Direct cause of the criticality accident was workers putting too much uranium solution into the precipitation tank

14 Why it happened Alternative operating manual -had not been through proper safety review. This manual authorised practices which eroded the safety margins, for example: Procedures were modified allowing the operators to use stainless steel buckets to mix the uranium solution rather than using a dissolution tank Workers poured the solution into the precipitation tank (for convenience) rather than the buffer tank The precipitation tank had not been designed for this job and its design contributed to the criticality

15 Major release of activity When radioactive materials are concentrated to a detectable level outside containment, the area affected is generally referred to as "contaminated". Such contamination presents a hazard because the released material emits harmful ionising radiation.

16 Chernobyl Disaster 1986 A catastrophic nuclear accident that released large quantities of radioactive particles into the atmosphere, which spread over much of the western USSR and Europe

17 What is nuclear safety? How it differs Why is it important? Consequences of poor nuclear safety Managing nuclear safety. Individual contribution

18 How do we manage it? The 4Cs Safe Operating Envelope Defence in Depth

19 How do we manage it? The 4Cs Safe Operating Envelope Defence in Depth

20 The 4 Cs Operations involving nuclear materials require strict and well maintained controls. Containment Control Criticality Keeping radioactive material where it is intended to be Keeping control on quantities and transfers of radioactive materials Storing radioactive material safely Cooling Keeping operating temperatures in the safe range

21 How do we manage it? The 4Cs Safe Operating Envelope Defence in Depth

22 Safe Operating Envelope Safe Operating Envelope Safe Operating Envelope recognises that normal plant conditions can fluctuate. Sets limits & conditions on how the plant can be operated, defined in the safety case Safety Case A structured argument, supported by a body of evidence, which provides a compelling, comprehensive and valid case that a system is safe for a given application in a given operating environment.

23 Safe Envelope Below the point where intolerable consequences to the public or workers are likely to occur or a plant state where an accident is likely to occur Safe Operating Envelope It is the plant state which can tolerate the worst reasonably foreseeable circumstances and still remain in the Safe Envelope Normal operating envelope Safe Operating Envelope Safe Envelope Unsafe Normal Operating Envelope Limits and conditions under which the plant is normally operated. Operating conditions and practices should always aim to ensure that the margins of this envelope are as far as possible away from the Safe Operating Envelope. The greater the margin, the more tolerance there will be to any slight deviations or plant abnormalities without challenging safety The aim is to ensure the plant state operates in the green zone

24 The Importance of Everyone s Behaviour What can operators do to ensure we always operate in the green zone? Understand the nuclear safety hazards along with their control measures on your plant/facility Understand how actions affect safety Adhere to procedures Stop if a problem occurs Don t take short cuts Consider what could go wrong and if appropriate have a contingency plan in place Embrace learning so we do not have repeat events Engage with Pre-Job Briefs: they are the opportunity to avoid making errors which might affect safety Do not tolerate degraded conditions

25 How do we manage it? The 4Cs Safe Operating Envelope Defence in Depth

26 Defence in depth Defence in Depth Physical Controls Procedural Controls Standards SQEP Organisational Culture What is defence in depth? Application of many layers of protection so that a single fault or error does not lead to an undesirable nuclear safety event or consequence.

27 Defence in depth Defence in Depth Physical Controls Procedural Controls Standards SQEP Organisational Culture Culture has a large impact on the effectiveness of the safety systems. Organisations that prioritise and value safety will ensure that defences are adhered to, e.g. safety mechanisms maintained appropriately, training is kept up to date.

28 Nuclear safety is a collective responsibility. No one in an organisation is exempt from the obligation Nuclear safety should undergo constant examination

29 In any organisation that handles nuclear material it is important that everyone understands how the actions they take and the decisions they make might influence nuclear safety

30 Summary Major Nuclear Safety Hazards are: Unplanned criticality Degradation of containment Major release of activity We manage Nuclear Safety through: The 4Cs Safe Operating Envelope Defence in depth

31 Part 1 Objectives (Review) To give Attendees an appreciation of: What nuclear safety is and how it is different from other types of safety The over-riding importance of nuclear safety and the consequences of poor nuclear safety Management of nuclear safety and how individuals can contribute