Safety

Safety is an urgent concern when associated with anything nuclear. The decommissioning process is certainly a moment in a nuclear reactors lifetime that requires a high level of safety and attention. This following information is related to the United Kingdom Atomic Energy Authority (UKAEA) and its decommissioning safety procedures. There are also other systems and methods explained to make the safety aspect of decommissioning effective and financially viable. This paper outlines some of the experience gained by the combined UKAEA and Contractor project team in obtaining safety approvals for the work.

Who takes care of Safety?

The decommissioning process requires timely clearance of protocol and documentation to be successful. All dismantling operations have to be subjected to stringent scrutiny of the safety arrangements and this is undertaken through the submission and approval of safety-cases and modification proposals.

Different strategies have to be adopted by the team to seek task safety approvals whilst maintaining the scheduling of the work program, and at the same time ensuring that safety standards are maintained.
Contractors and governing bodies like the UKAEA (United Kingdom Atomic Energy Agency) team are contracted to decommission reactor sites. The project management of the decommissioning, the dismantling itself, the development of the tooling and methodologies and the preparation of the associated safety submissions are all the onus of these said bodies.

Project Management of the Decommissioning

Different protocols are established within these bodies to ensure the safety of their employees and the public. Inventories of Nuclear Liabilities and the establishment of Nuclear Safety Accounts and Safety Assessment and Feasibility Interim Reports help make the decommissioning process manageable and financially viable.

Committees categorise different safety systems. An example of the UKAEA safety system is as follows:

The objective of this process is to determine the level of scrutiny that should be applied to the submission, and is not any comment about how realistic the hazard is perceived to be. Subsequently there would be other protocols adopted by other governing bodies to ensure safety and a means to categorise the level of safety.

The Inventory of Nuclear Liabilities involves:

• Drawing up a register specifying the location and condition of all nuclear facilities and all sites containing radioactive substances on Belgian territory;
• Estimate of the cost of decommissioning and cleaning up these facilities and sites;
• Evaluation of the availability of sufficient funds to carry out these future or ongoing operations;
• Updating the inventory every five years.

Nuclear Safety Account

To assist in the decommissioning process there are a number of methods employed to ensure decommissioning financially viable. The uses of Nuclear Safety Accounts in Europe have been a decision that has answered the concerns for finance.
As an example a result of the Munich Summit, a multilateral fund was established with the agreement of the European Bank for Reconstruction and Development to perform the management function for a Nuclear Safety Account. The mandate of the Nuclear Safety Account is to use donor contributions for the execution of priority, short-term projects to complement bilateral programs.
Figures quoted and established for projects total EUR 262 million have been awarded.

Further examples of the Nuclear Power Plant projects have been contracted at Kozloduy in Bulgaria, at Ignalina in Lithuania, and at the Kola, Novovoronezh and St. Petersburg nuclear plants in Russia.
The last project awarded is in Ukraine, which provides short term safety improvements for the remaining operating unit at Chernobyl and decommissioning facilities in preparation for closure.

Safety Assessment and Feasibility Interim Reports

The disposal of decommissioned nuclear reactor waste is a very real burden. The use of these safety and feasibility reports make a way for the viability of removal and safe storage of nuclear waste. These assessment and feasibility reports are preliminary reports on the safety and feasibility of deep underground disposal. An example would be the SAFIR 1 report which assessed the work carried out between 1974 and 1988 on the possible disposal of radioactive waste in the Boom clay layer in Belgium. The SAFIR 2 report assesses the work carried out in the years 1990-2000.

The Dismantling Itself

During the Decommissioning process the health and safety of employees, contractors and the general public is paramount. Goals are that no harm should result from activities.

Working towards this, goals strive to:

• Eliminate injuries at work
• Prevent incidents but maintain effective emergency arrangements
• Achieve and sustain an excellent safety culture
• Learn the lessons from events, implement corrective actions and seek out and use good practices wherever we may find them
• Ensure that activities, products and services are in compliance with applicable legislation and meet the requirements of good practice and applicable standards of employment health and safety performance.

In short, safety is of the utmost importance. It is an integral part of everything that is done.

An example of the methodology in action is the following report outlining guidelines followed by a joint U.S. and Kazakhstan agencies effort. This decommission was for a sodium cooled reactor in Kazakhstan.

Technical Strategy For The Project

The strategy for development of the plan involves a series of tasks, the basic accomplishment of which is in a series of joint workshops, training sessions, and/or working meetings of all participants occurring either in the U.S. or Kazakhstan --- dependent on cost effectiveness and travel restrictions. In these workshops the technical experience of decommissioning sodium cooled reactors will be transferred to Kazakhstan engineers and scientists with the particular knowledge of the BN-350 reactor systems. In parallel with the workshops, detailed technical design concepts will be developed for near-term key activities such as sodium draining and processing. All this information will be combined in a technical decommissioning plan. The tasks are as follows:

Tasks 0 and 1 - Develop Initial Workshop Plans and Conduct Workshop to Develop the Format, Content, and Initial Data Requirements for the Plan

The key goals of this task are to develop the detailed format and content of the Shutdown Plan for International Review (henceforth called 'the plan'), to develop preliminary data needs to write the plan, and to prepare the detailed plans for the writing of the plan. The format and content document should be in sufficient detail so that an appropriately assigned individual could develop the information for an assigned section of the plan to permit acceptable drafting of that section.

Task 2 - Develop the Information Base and Strategy for the Plan Development

The intent of this task to collect all the data that is needed to compete the plan. The available data identified in task 1 is collected and evaluated, and additional data needs are identified as necessary based on this assessment. A strategy for fulfilling the data needs is agreed upon. It is envisaged that this step will be performed in a second 1 to 2 week workshop. The predominant data need is expected to involve a) confirming the list of actions and tasks needed to place the plant in SAFESTOR, and b) gathering support
information to document the logic, schedule, and resource requirements for those actions and tasks. Quantities of radioactive waste, doses, etc., and other task specific information may also be convenient to estimate with analysis of each of these actions so that it may be systematically tallied in the plan. Clear direction is given in the workshop on how the data is to be collected. Assignments are given at the end of the workshop for the collection of the data in conformance with the strategy and the workshop concluded. Personnel return to their home bases to collect the information as necessary. Information already collected at the workshop from available information
is archived by appropriate section in the format and content documents that it supports. Detailed technical concepts developed in task 6 will begin to be fed into the planning process at this time.

Task 3 - Develop the Plan

This task includes 2 aspects:

• Assembling all the data and information gathered in task 2, reviewing it, and creating a rough draft of the plan. This will be performed in a final (third) 1 - 2 week workshop. The most difficult part of this task is probably assembling the resource-loaded schedule.
• Complete the final writing of the plan. A 'writing team' is agreed upon to take the rough draft and turn it into a final document ready for review.
  The technical concepts being developed in task 6 will continue to be updated as more information is obtained.

Task 4 - Review, Revise, and Approve the Plan

This task takes the conformed draft plan and assures it is acceptable to the workshop participants, U.S. and Kazakhstan decision makers, and it is appropriately approved for international review.

Task 5 - Conduct International Peer Review of the Plan

In parallel with the performance of this contract, the joint Kazakhstan-U.S. decision-makers communicate with the IAEA to set up an international peer review of the BN-350 shutdown plan. Conceptually, the IAEA will administer the peer review by identifying and recruiting international experts to review the plan. These experts cannot be the ones who may have been involved in the creation of the plan. Revision B of the draft conformed plan is sent to these reviewers approximately 1 month prior to a review meeting.
The review meeting is conceptually sponsored by the IAEA and conducted in Vienna.

Task 6 - Concept development of Near-Term Tasks Necessary for Detailed Planning

This task develops the detailed design concepts for near-term tasks where there is a substantial amount of development work required in order to figure out what to do specifically sodium draining and processing. Unless this is done, the planning work that will be performed will be based on conjecture on areas that will take place in the near term potentially invalidating the plans for the follow-on work. The team required for the general planning work is comprised of engineers and scientists with a broad plant knowledge. Developing the detailed concepts requires the addition of specialists to develop the specific design concepts.

Specific detailed concepts need to be worked out for the following:

• Sodium draining
• review for trapped residual sodium areas
• develop strategy for draining trapped sodium
• determine need for aux heating
• development of sodium draining process)
• Sodium Processing
• Determine location of processing facility and connection to plant
• development of sodium processing concept
• review of environmental acceptability of processing product
• development of licensing requirements for the facility)

Task 7 - Contract Adminisatration

This task involves work by the Kazakhstan Nuclear Technology Safety Center to manage the designated work with the other agencies within Kazakhstan and Russia in support of this project. KNTSC responsibilities include general coordination of all project activities, administrative review of deliverables (to assure completeness prior to payment), translation of the deliverables as necessary, arrangement for and implementation of payment and material procurements/transfers to appropriate personnel at the
other agencies, confirmation of payment/material receipt, administrative and logistic support for project workshops, and maintenance of financial records, wages paid, and other payment documentation.

Development of the Tooling and Methodologies

The goal of decommissioning:

• The decontaminating of facilities (activities intended to reduce, or even eliminate, all traces of contamination);
• The dismantling of facilities (all dismantling, cutting and demolition operations with a view to withdrawing contaminated and/or activated materials and structures from service);
• The management of the radioactive waste resulting from the operations above
  All these operations, which are performed with due consideration of the safety of the operators taking part and of the facilities and sites concerned, are intended to bring the residual radioactivity to a level permitting the release of the facility for unrestricted use.

Other procedural methods to ensure safety include categorisation of risk. An example of categories established by the UKAEA include:

There are 4 categories:

• Category D refers to a building incident with trivial affect on the operator,
• Category C being a more serious event affecting only the operator whilst
• Category B has effects outside building
• Category A has effects outside the site boundary.

Release defined:

Release is defined as the removal of all further regulatory radiological control by the competent authorities (Federal Agency for Nuclear Control) of substances, materials, facilities or sites for the reason that the associated risk has become sufficiently low. Implicit in the concept of release is the understanding that once said substances, materials, facilities or sites have been released, they are no longer subject to any restriction or radiological control. Consequently, radioactive materials that has been released, can be treated as residues or ordinary effluents, and substances, materials, facilities or sites that have been released for re-use or recycling can be sold or transferred to any person, company or association that is then free to use them for any purpose.
A way in which the decommissioning process has been made "cleaner" is the use of recycling of nuclear decommissioning waste.
In Belgium the ONDRAF/NIRAS bodies have adopted the following methods:

The decommissioning of Belgian nuclear facilities will be the main source of the radioactive waste that bodies like ONDRAF/NIRAS manage. Belgian has therefore opted resolutely for a strategy of minimising the volume of radioactive waste produced during decommissioning operations, through extensive decontamination and the recycling of decontaminated materials. As a result, ONDRAF/NIRAS predicts that around only 3% of all the materials present on a nuclear site will need to be managed as radioactive waste.

For more information about the state of affairs at European Union level see: The European Commission Website on Decommissioning of Nuclear Installations

Services in Safety and Reliability in regards to tooling and methodology include the following:

• Safety Criteria Development (design phase, operating facilities, plant decommissioning).
• Fault/Hazard Identification in support of safety, reliability and risk assessments, including HAZOP studies, FMEA techniques etc.
• Safety Assessments including supporting analysis of hazards, vulnerability and damage.
• Availability, Reliability & Maintainability of existing and novel Process Plant.
• Maintenance Optimisation including Reliability Centred Maintenance.
• Design Optimisation/Justification, from a safety viewpoint.
• ALARA/ALARP Studies, both qualitative and quantitative.
• Safety Case Preparation, to meet HMNII and other licensing requirements.
• Independent Peer Review of safety, reliability and risk assessments and safety cases, on behalf of both the licensee and the licensing authority.
• Consequence Modeling, to address effects to both on-site and off-site groups.

References:

1. http://www.nirond.be/engels/7.7_Ontmanteling_eng.html
2. http://www.ukaea.org.uk/wagr/docs/IBC_RCA.pdf#search=
   'decommissioning%20%20safety'
3. http://www.bnfl.co.uk/index.aspx?page=123
4. http://www.ntsc.kz/projects/istc513.htm