1 ESTABLISHMENT OF REQUIREMENTS Module “DECOMMISSIONING PROCESS” Project BG/04/B/F/PP-166005, Program “Leonardo da Vinci”

Project BG/04/B/F/PP-166005, Program "Leonardo da Vinci"

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Contents

1.1 Main stages1.2 Key issues specific to decommissioning1.3 Main areas and activities1.4 Differences between decommissioning and operation


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Training objectives

Upon completion of training trainees should be able to:

– Explain the main tasks of decommissioning.– Determine the main decommissioning areas and

activities.


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1.1 Main stages

The term decommissioning refers to administrative and technical actions taken to allow removal of some or all of the regulatory controls from а nuclear facility (except for а repository, which is, by definition, subject to closure

and not decommissioning).

(IАЕА, “Decommissioning of nuclear power plants and research reactors”, Safety Standard Series WS-G-2.1, Vienna, 1999)

Decommissioning


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Decommissioning process

All main activities in the decommissioning process are of significant direct or indirect importance to safety. They are connected to:

• the immediate impacts on personnel safety;• shock on effects on safety during implementation of next

step operations, including those that a re envisaged to take place after a considerable period of time elapses;

• impact on inhabitants and the environment;• impact on future generations.


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Decommissioning strategies

• Immediate dismantling• Deferred dismantling (safe storage, safe enclosure)• Entombment


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Construction2 years

The main targets of « Passage »

An example of decommissioning strategy –« Passage »Project, Grenoble, France

Science and Support

35 years

Dismantling4 years

Cleaning6 years

Authorisation

Clearance


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Main stages of decommissioning

Decontamination & Dismantling

Phase

Surveillance & Maintenance

Phase

Preparation Phase

Decontamination& Dismantling

Phase

Preparatory Phase

Final Phase


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Preparatory phase

• specification of the decommissioning plan • defueling and removal of the radioactive materials

generated during operation;• evaluation of the quantity of which are to be generated

at the dismantling;• preparation for and obtaining of licenses/permits;• actualization of the technical documentation of the

nuclear facility;• including changes to the QА system;• development of training programs and training the

instructors for maintaining qualification (requalification) of the personnel


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Surveillance and maintenance phase• control over the normal operation and the condition of the

systems;• environment monitoring;• classification the equipment;• partial removal of the equipment;• treatment and conditioning of the RАW;• actualisation of the decommissioning plan;• preparation for D&D stage activities;• development and implementation of training.


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Dismantling and decommissioning phase

• licensing of activities, related to dismantling;

• installation of decontamination and dismantling equipment;

• decontamination and dismantling;

• qualification of equipment and materials;

• treatment, conditioning, transportation and storage of RAW;

• on-site and environmental monitoring;

• site release (transition to the final phase – surveillance and release from regulatory control.)


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KNPP units 1,2 decommissioning: Main concept

• Post operation and preparation period• Safe enclosure (35 years)• Deferred dismantling

(PHАRЕ Project BUL 9608-01-01 L001, Bеlgаtom– ЕWN, 2000)


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1.2 Key issues specific to decommissioning

• Responsibilities• Regulatory framework • Safety• Planning • Considerations for radiation protection and environmental

protection • Wastes


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Key issues: Responsibilities

States shall include provisions in their national legal framework for:

• decommissioning, including the preparation of decommissioning strategies and plans;

• establishment of а regulatory body for controlling decommissioning activities;

• establishment of funding mechanisms for decommissioning;• development of а system for the management of the material

resulting from decommissioning.


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Key issues: Responsibilities

The operator shall be responsible for all aspects of safety and environmental protection during the decommissioning activities, i.e.:

• adequate level of safety;

• perform softy and environmental impact assessments;

• prepare and implement appropriate safety procedure;

• apply good engineering practice;

• ensure that staff are properly trained, qualified and competent;

• establish а quality management programme, and

• keep and submit records and reports as required by the regulatory body.


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Key issues: Regulatory framework

The regulatory body shall establish safety and environmental criteria for the decommissioning, including:

• conditions on the end points of decommissioning; • limits and conditions for the removal of controls for facilities

containing radionuclides and criteria for the clearance of material during and following decommissioning;

• criteria for determining when а nuclear facility, or part of а facility is permanently shutdown;

• require baseline survey of the site, including radiological conditions, prior to construction to obtain information that can be used for comparison purposes with the end state after decommissioning


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Key issues: Safety

Ensure the protection of workers, the public and the environment by means of:

• thorough safety assessment of the hazards, fuel, stored on as part of а defense in depth system;

• maintenance of integrity of the spent -site in а fuel pool;

• taking into account in the safety assessment the total contamination and activation of the instillation after removal the RАM;

• considering the new additional hazards created by specific decommissioning activities (decontamination, dismantling and demolition, removal of equipment and systems …);

• defining and implementing the protective measures for industrial safety, fire protection and emergency planning.


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Key issues

• Planning– The adequate and timely planning of decommissioning activities to a very

large extent reduces the risk and radiological consequences, concerning decommissioning activities.

• Considerations for radiation protection and environmental protection

– It is necessary that the national radiological protection requirements should be in compliance with the International basic standards on safety.

• Wastes – RAW generation should be as less as possible (application of adequate

techniques for decontamination and dismantling, recycling and re-use of materials).

These problems are considered at length in the “Decommissioning Management ” course.


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1.3 Main areas and activities

The main activities with an impact on safety during decommissioning include:

• Initial characterization of the nuclear instillation• Defueling• Containment maintenance and modification• Decontamination• Dismantling• RАW management (treatment, conditioning, storage) and

transport• Final radiological characterization• Organization and administrative control


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Main areas and activities

• Initial characterization of the nuclear instillation

• Defueling

Radiological characterization of all premisesRadiological characterization of all premises

Final clean-up of pool channels and plug storageFinal clean-up of pool channels and plug storage


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Main areas and activities

• Containment maintenance and modification

• Decontamination• Dismantling


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Main areas and activities (cont.)

• RАW management (treatment, conditioning, storage) and transport

• Final radiological survey


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1.4 Differences between decommissioning and operation

Operations Decommissioning

Reliance on permanent structures for the operating life of the facility

Introduction of temporary structures to assist dismantling

Safety management systems based on an operating nuclear facility

Safety management systems based on decommissioning tasks

Production oriented management objectives (except perhaps in research facilities)

Project completion oriented management objectives

Routine training and refresher training

Retraining of staff for new activities and skills or use of specialized contractors


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Differences between decommissioning and operation (cont.)


Permanent employment with routine objectives

Visible end of employment — refocus of the staff's work objectives

Established and developed operating regulations

Change of regulatory focus

Predominant nuclear and radiological risk

Reduction of nuclear risk, changed nature of radiological risk, significantly increased industrial risk

Focus on functioning of systems

Focus on management of material and radioactivity inventory (e.g. for waste minimization)

Repetitive activities One-off activities

Working environment well known

Working environment unknowns possible


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Differences between decommissioning and operation (cont.)


Routine lines of communication New lines of communication

Low radiation/contamination levels relatively unimportant

Low radiation/contamination levels important for material clearance

Access to high radiation/contamination areas unlikely or for а short time

Access to high radiation/contamination areas for extended periods

Routine amounts of material shipped off-site

Larger amounts of materials shipped off-site

Relatively stable isotopic composition

Isotopic composition changing with time


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References

1. IАЕА, Decommissioning of nuclear power plants and research reactors, Safety Standard Series WS-G-2.1, Vienna, 1999

2. IАЕА, Decommissioning of Nuclear Facilities, DRАFT SАFЕTY RЕQUIRЕMЕNTS, DS333, Nov 2004

3. Transition from Operation to Decommissioning, IАЕА TRS No420

Documents

1 ESTABLISHMENT OF REQUIREMENTS Module “DECOMMISSIONING PROCESS” Project BG/04/B/F/PP-166005, Program “Leonardo da Vinci”