Kozloduy’s new future

30 April 2001

At Kozloduy is being upgraded, with the help of contractors from several countries and international lending agencies. The key is transparent and effective planning

The two VVER-1000 units at Kozloduy 5 and 6 were built by Russian companies in the late 1980s and early 1990s, providing 24% of Bulgaria’s electricity. There are 204 modifications in the Kozloduy 5 and 6 modernisation programme to bring the plant up to Western standards. They are being made by the plant personnel and external contractors. By early 2001, 76 modifications had been completed.

After a dedicated company, Kozoduy NPP, was separated from Bulgaria’s Natsionalna Elektricheska Kompania, it became the client in this programme. On the other side, the contractors are Westinghouse and the European Consortium Kozloduy, comprising Siemens and Framatome (now one company known as Framatome ANP) and AtomEnergoExport. Kozloduy has funded its own part of the programme, while work by the international contractors was funded by Citibank (for Westinghouse), the EC’s Euratom (for Framatome ANP), and Roseximbank (for AtomEnergoExport).

Contracts are based on the conditions published by the Federation Internationale Des Ingenieurs-Conseils, carefully defining the responsibilities of client and contractors, the design and operational information to be provided to the contractors by the client, the contractors’ deliverables and their time frames for execution of work and delivery of systems, and the prices, payment methodologies and schedules. The international loan agreements impose stringent requirements on planning, expenditure and implementation. The normal annual refueling outage at Kozloduy is limited to 90 days. Modifications are therefore distributed over several years and workload analyses are essential to verify requirements versus availability, and check personnel requirements. The entire project is expected to take 5 years.

Contractors want to complete the work and bring in positive cash flow quickly, but are constrained by the need to obtain plant design and operating data from the client. Another constraint is obtaining regulatory acceptance of the design, documentation, and implementation of the modifications.

Delays attributable to the client will represent time extensions in favour of the contractors, and extra costs against the client, while delays by the contractors will result in penalties. Either way, the client is not compensated for the loss of revenue for electricity supplied to the grid.


There are two types of ‘deliverables’ in the programme: hardware, and studies or analyses. Where the deliverable is hardware the following project phases are:

•Input data, prepared by the client for the contractor.

•Detailed design, prepared by the contractor and accepted by the client.

•Licensing, submitted by the client and approved by the authority.

•Supply, including manufacturing, factory acceptance test (for acceptance by the client) and delivery to site.

•Installation, testing by the contractor, and turnover of certificate to the Client.

Where the deliverable is a study, the phases are:

•Input data, prepared by the client for the contractor.

•Preparation of reports by the contractor and acceptance by the client.

•Submission of licensing data by the client and approval by the authority.

During the detailed design phase detailed installation schedules are agreed based on the current contract agreements. The schedule must be integrated with the plant outage plan, and be subdivided into daily activities.

The list of activities to be carried out is developed using the following planning inputs:

•Outage plan for units 5 and 6, with mandatory constraints including a fixed duration of three months, starting usually in April (unit 5) and August (unit 6), to be confirmed by November of the previous year.

•The contractors’ schedules, prices and workload.

•The client’s work, which depends on available resources (manpower and materials) and funds.

•Resources from the client allocated to support the contractors.

•Other site activities, not associated with the modernisation, that affect the outage


The project schedule is finalised using the critical path method (CPM) by creating a logic network for each modification. The following principles are applied:

•’Modification commencement’ date is after ‘contract effective’ date.

•Input data is delivered before the kick-off meeting and detailed design preparation.

•Detailed design acceptance timeframe is limited to 60 days.

•The detailed design must be accepted before it is submitted to the licencing Authority.

•The modification is licenced before installation begins.

•Equipment is delivered to site before starting any dismantling or preparatory work.

•All installation and testing is finish before the outage ends.

The CPM allows the schedule to be adjusted quickly if there is a change in the key dates, if input data is delayed, or if permissions are not received on time. Modifications are interlinked if they are being carried out at the same time, or if they are connected in another way.

The duration of activities in the main contracts are defined in the contract schedules with input from the client. The time required for the client to review and accept the detailed design is estimated with some contingency. This chain has an overall duration of less than 60 days. An uncertainty exists in estimating the time required for the authority to issue licences. The licencing chain thus has an overall duration of 90 days. The duration of the client’s own modifications is based on expert judgement of the tasks and sub-tasks.

It is not appropriate to apply productivity standards, because of constrained conditions in which the modifications must be implemented and the need to replace or install equipment in a congested area. However, international productivity factors can be used to support estimates of task duration in lesser constrained conditions.

The various activities are coded, for the modification, the type of product (study or physical work), phase (engineering, licensing, procurement or installation), the responsible party, task and applicable project milestone, among others.

Schedule constraints include programme start date, the ‘contract effective’ dates for contractors and client, the mandated start and finish of the outages, and external constraints on the partners. Once the contractor delivers the detailed design, acceptance by the client becomes a fixed constraint. The client’s tasks are planned within 60 days, so the free float of these chains will be monitored against the contractual term for review and acceptance of the detailed design, to avoid claims by the contractors. This process is repeated for each modification in at least two cycles of review and acceptance.

The end of the licencing activity becomes a fixed constraint as soon as the safety statement is presented to the authority.

Although the client has limited influence in modifying this, the free float variance of these chains is essential for the project reviews by the client and contractors, to expedite supporting documents requested by the authority, and to perform ‘what-if’ analyses. Around 50% of modifications are subject to licencing, and careful and precise planning is needed to ensure the work is not halted due to lack of permits. If there are delays due to licencing, the contractors are exempted of responsibility, and the client has to bear the time extensions and extra costs.

The project is scheduled using Primavera P3 planning software. Four calenders are used: seven days per week for the contractors’ schedules and Level 1 project schedule; five days per week (excluding weekends) for resourcing; four days per week (excluding weekends and Mondays) for contract meetings and six days per week (excluding Sundays) for installation.

Planning depends on information from the contractors, but the client uses preliminary installation plans, to be incorporated into the project schedule, to make its own comparative analyses.

A major output from the schedule development is a ‘schedule of payment milestones’, created as successors of the contractors’ activities. The milestones represent completion of the contractors’ deliverables, include delivery and acceptance of detail design, factory acceptance testing, delivery of equipment, end of installation and take-over certificate. For each modification, part of the price is paid at the contract effective date, and the modification commencement date.

The simulated price of a sample modification was used to verify the adequacy of the planning technique, and provide a time-distribution of the cash requirements for performing a modification.

The aggregate of the cash requirements for different modifications within one sub-project provide the overall cash requirements and timed distribution. These automatic planning calculations provide the basis for requests to the lender institutions for the loan disbursements necessary.


On the contract effective date, the sub-project schedules become baseline schedule for the contractors, and in the related planning programme the client’s modifications also become baseline.

The Level 1 project schedule is updated and issued monthly, using data from the contractors and client. The main purpose is to verify if the activities are being performed as planned, and if not, what corrective actions are being implemented and what is the revised schedule. Level 2 activities are updated weekly to keep the schedule ‘alive’.

Information in the contractor’s progress report is cross-checked with the client’s internal data. Interfaces between contractors and client, and among the contractors, require specific attention in the schedule update. Variance analyses will reveal unacceptable situations that could require corrective actions.

Scope changes, presented by the client or contractors may requires planning changes, and can be accepted only if they are reviewed and approved by the client project manager.

Updates of the schedule show the current schedule in comparison with the baseline, along with variance reports for early start or finish dates, or for activity floats. It also includes a ‘short term look-ahead’ of activities for the next two months, and an update on the client resource requirements and availability.

The schedule may need revision whenever completion dates change. The client’s planning staff produces an immediate warning for the project management information and reference. Recovery actions must be defined, approved and implemented by both the client and the contractor. If recovery actions fail to bring the schedule back to the planned dates, the outage implementation may be postponed, causing disruptions on the daily plans, and eventually economic losses. The client project management must authorise any revision to the project schedule.

Approved variations for the contractors, due to scope changes or specific requests, may also lead to the revision of the schedule in the next monthly update.


Simulations of adverse conditions are performed regularly, in which new probable planning data are input into the project schedule. This allows possible schedule extensions, impacts on the pre-determined outage, and overloads on the client staff to be anticipated. These ‘what-if-analysis’ reports are presented to the client to assist in the decision process, and include scope-changes requested by the contractors.

External constraints such as licencing delays may also be examined, and target dates for licensing can be communicated in advance to the authority to allow for proper internal planning.

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