R4.02/94 Concept design Civil Plutoni

To perform the conceptual design for a Civil Plutonium (Pu) Storage Facility for 50 T of PuO2 from VVER reactors (civil plutonium) for Nuclear Establishment PO Mayak, Russia, including safeguarding and physical protection aspects.

In particular the Conceptual Design takes into account the collective technologies currently available and being operated within Western Europe and includes consideration of the rules and regulations applicable to the country of location. It acknowledges that different cultural constraints exist between nations and that custom and practice may also reflect local requirements.

The project outcome represents the collective recommendations of Western European companies for the specific needs of the Mayak Site. Effective Technical and Engineering interfacing between Mayak, VNIPIET and the contractor ensures open exchange of views and is a key feature of the recommendations of this project. The interface discussions have to include representatives from the Technical/Operational and Engineering discipline available at Mayak and technical/engineering input from VNIPIET. VNIPIET was expected to provide significant technical and engineering input to the project data determination, to participate actively in the optioneering reviews and to fully support the process to determine an optimised conceptual design.

The project team consisted of technical and engineering specialists from BNFL (UK), Belgonucleaire (Belgium), and SGN (France), integrated into a Consortium. The Consortium team was managed by BNFL. The team interfaced with representatives from PO Mayak Russia. This interface was facilitated by technical and engineering specialists from the Nuclear Institute VNIPIET, St. Petersburg.

The outline tasks for the Consortium (as defined in the Contract) included:

• Establish current conditions at Mayak;
• Consider Western Europe best practice;
• Take account of Russian Rules and Regulations;
• Assess the existing facilities;
• Propose concept design options;
• Review and agree concept proposal;
• Produce supporting safety documentation;
• Compile final report.

A Technical Questionnaire, supported by analysis and review where possible, is giving the basic data used to support the concept proposals. The data provided were to be used in the form they were provided, with the exception of clarification and increased understanding. The VNIPIET Institute facilitated the technical interaction and dialogue exchange and was the principal generator of data in response to the questionnaire.

A compendium of Russian Rules and Regulations applicable to the project were also provided by VNIPIET. A technical seminar was held in Brussels. Nuclear installations in Belgium, France and the UK were visited with particular reference to plutonium storage facilities.

The documentation recognises that technological differentials exist and are practised in the respective national nuclear industries. The concept design considers these differentials and makes its recommendations based upon Western practice and minimal recognised Safety Standards. The conceptual design is recommended as a collective proposal based upon available current data, accepted Western practice and considering Russian Rules and Regulations.

Main deliverables:

A. Technical Questionnaire.

The Technical Questionnaire identifies the key specific information related to the physical and chemical characteristics of the PuO2, the type of container in which it is to be stored and the site location characteristics necessary to support the conceptual design of a high integrity store for plutonium. In addition it identifies the rules and regulations applicable to the site.

B. Assessment of PuO2 Accumulation and Storage Status at PO Mayak.

This document responds to the technical questionnaire and provides the key specific information related to the physical and chemical characteristics of the PuO2, the type of container in which it is to be stored and the site location characteristics necessary to support the conceptual design of a high integrity store for plutonium. In addition it lists the Rules and Regulations applicable to the site.

C. Functional Specification.

This document defines the functional requirements of a new facility for the storage of civil grade plutonium at Mayak.

D. Conceptual Design of the Store and Handling.

This document describes the conceptual design of the store vault, cooling system and the handling operations for loading material to the store. It also details the thermal calculations which support the cooling system proposals.

E. Process Auxiliaries.

This document describes the facilities related to the material receipt at the store. It covers the cask and container handling and safeguards measurements. Additional process controls are summarised.

F. Building Auxiliaries.

This document describes how the conceptual building layout and associated facilities contribute to the safe design and operation of the proposed Mayak civil plutonium store.

G. Safety System.

This document describes the monitoring and alarm systems necessary for the detection and mitigation of potentially hazardous conditions.

H. Time Diagram of the Receipt Control and Storing Operations and Rate of Delivery.

A time diagram of the receipt, control and storing operations is carried out in order to evaluate the capacity of PuO2 management of the proposed MAYAK Pu Store and the manpower requirement. Based on this time diagram and a preliminary analysis of the critical path of the various operations of control and transfer, indications are given on the adaptations of the manpower and equipment in order to address or approach the first two years delivery rate (15 t/year).

J. Review of Conceptual Design -VNIPIET / Mayak / EFCC.

This document summarises an evaluation of the engineering concepts, identifying the 8 key drivers influencing the design of the facility. Review of the concept options was undertaken to optimise the design proposal to be cost effective in meeting the design and contract requirements.

K. Option of Power Plutonium Storage.

This document describes the basic design criteria and technical solutions related to the power plutonium storage design established by VNIPIET. It gives one of the alternatives to arrange power plutonium storage at Mayak.

L. Waste Confinement and Management.

This document addresses the provisions implemented in the design of the store to fulfil the requirements of reliable containment and adequate management of radioactive materials.

M. Radiation Protection.

This document reviews the features of the plutonium storage facility that ensures the adequate protection of personnel and public against the effects of ionising radiation.

It addresses the shielding, operational procedures and monitoring means that have been identified in the concept design to:

• Keep individual dose intakes within acceptable regulatory ranges under normal conditions and under some off-normal situations;
• Keep collective occupational exposures at reasonable levels given that the facility is properly operated.

N. Accident Analysis.

The aim of the accident analysis is to provide early demonstration that the concept facility can meet the requirements of the Russian Federation for abnormal event and potential accidents.

Additionally the accident analysis will assist in the optimisation of the concept design defence-in-depth provisions that:

• Limit the likelihood of accident conditions (preventive safety features);
• Mitigate the consequences of any consequences that might arise (mitigating safety features).

O. Operating Controls and Limits.

This document reviews the control features of the plutonium storage facility from the viewpoint of the safety limits in the operation conditions and of the associated surveillance requirements.
The safety limits refer to the measurable variables which are used in order to control the performance of the equipment and the integrity of the confinement barriers. The lowest acceptable level of performance for a system or component should be established on the basis of technical limiting conditions related to the safety aspects: e.g. the mass of fissionable material in the system, the concentration of radioactive material, the temperature. The safety criteria of the conceptual design deals with the allowed limits of the measured variables.

Recommendations:

The following recommendations have been issued:

• The concept design shall be used as a basis for detailed design and construction, ensuring that all local and regulatory safety criteria are taken into account;
• Development of the concept proposal should consider the specific features which reflect local custom and practice as outlined in this project;
• All data, including the data related to the physical and chemical characteristics of the PuO2, the type of container and the site location characteristics, should be verified as the concept design is developed;
• The storage concept design should further consider the necessary programme for material conditioning and packaging;
• The organisations which have contributed to the preparation of this report should be invited to participate in the further development of the concept design.