Once the contracts are awarded, the following expert functions will be required in support of the plant refurbishment phase:
— Detail planning, walkdowns and field engineering to install SSC changes and any new system additions;
— Demolition specialists to dismantle existing structures and remove old equipment;
— Construction contractors for new SSC installations;
— Commissioning specialists for testing, commissioning and return to service with replaced, refurbished and new SSCs.
6.3.1. Strategy for equipment replacement
Heavy component replacement projects, particularly those related to SSCs inside the reactor building, require specific considerations with regard to site preparation activities, safety, collective radiation dose, cost, sequence of TABLE 12. EXAMPLE OF A TABLE OF CONTENTS FOR A TURNKEY LTO CONTRACT (cont.)
12. Contractual price and financing 12.1. Base price
12.2. Price escalation and adjustments 13. Terms of payment
14. Force majeure 15. Termination of contract 16. Applicable laws
17. Jurisdiction: Disputes and arbitration 18. Organizational matters
18.1. Representatives 18.2. Addresses
18.3. Shipment and transportation 19. Service contract
activities and schedule. The individual component replacement strategy should be developed in close association with the component manufacturers and installers.
Each component replacement strategy [40] and its cost will be highly dependent on the type of component and on its technical specification, which can include:
— The replacement component supply scope, e.g. the specified length of the reactor coolant loop spool to be replaced; the replacement technique of the steam generators, whether supplied in one or two fragments; the reactor vessel head replacement specification, whether bare minimum or with welded CRDMs; the core shroud replacement specification in boiling water reactors (BWRs), whether complete or partial; the shipment method; the ground transportation method within the NPP site (e.g. the choice of the transportation path, the need for ground reinforcements, the component orientations); the need for temporary facilities on-site as, for example, a temporary facility for the steam generators, when end machining is performed on-site; and a temporary facility for welding a new or the old CRDMs to the replacement reactor vessel head or for machining the reactor coolant loop nozzles.
— The hoisting of the component inside the containment building and the overall handling sequence.
— The access route inside the containment building may require temporary demolitions to avoid interferences against existing design features such as SSCs along the access path and physical clearances of the main crane beams (two or three point lift, crane upgrading required, etc.).
— The need for temporary containment openings in the reactor building wall if one of the steam generators does not fit through the equipment hatch, either because of an unsuitable location or because its inner diameter may be too small. The cost of temporary openings will depend on whether the reactor building wall is made of pre-stressed or reinforced concrete. It will also depend on the choice of the opening location (roof or wall), on the design of the reactor building wall (integrated steel liner or epoxy finish), or the presence of interferences with external components (e.g. storage tanks, adjacent buildings, underground channels) that may limit the location of the temporary containment opening. The reactor building wall cutting technique also affects cost.
Among the proven techniques are core drilling, diamond saw blade cutting, controlled hydraulic explosive, thermal or jet stream process.
— The design of the concrete and metal structures inside the containment building, which may require cubicles and concrete floors at various levels to be modified.
— Major refurbishments/replacement of non-safety equipment are usually aimed at improving the efficiency, availability and reliability of the plant, or at optimizing O&M costs. Some specific replacements/refurbishments may also be required if the option of power uprate is considered for the LTO process.
6.3.2. Material procurement and installation
During the LTO implementation phase, the following are required:
— Planning, layout and engineering of the refurbishments and of any new system additions;
— Experts in bid evaluation, contract preparation, contract placement and supervision;
— Safety specialists to prepare the licensing documentation (FSAR, environmental report, etc.), licensing submissions and other regulatory activities;
— Demolition specialists to dismantle existing structures and remove old equipment;
— Construction contractors for new SSC installations;
— Commissioning specialists for testing, commissioning and return to service with replaced, refurbished and new SSCs.
With regard to the main contractors, equipment vendors and suppliers are normally pre-qualified. The pre-qualification requires that these vendors offer recognized capabilities and experience, including qualified processes, for similar work in engineering, licensing, manufacturing and installation of the main components of the primary circuit in similar NPPs.
The process of selecting the final suppliers begins with a request for quotation (RFQ) sent to all the pre-qualified suppliers, inviting them to propose part or all of the scope of supply.
TABLE 12. EXAMPLE OF A TABLE OF CONTENTS FOR A TURNKEY LTO CONTRACT (cont.) 12. Contractual price and financing
12.1. Base price
12.2. Price escalation and adjustments 13. Terms of payment
14. Force majeure 15. Termination of contract 16. Applicable laws
17. Jurisdiction: Disputes and arbitration 18. Organizational matters
18.1. Representatives 18.2. Addresses
18.3. Shipment and transportation 19. Service contract
— All relevant design documentation and as-built data concerning the component to be replaced, and its interfaces with the environment (inside and outside the containment building);
— A specific request for any modifications (interfaces, power upgrading or material improvement);
— Conditions of implementation (outage constraints);
— Possible replacement strategies.
The final orders will be placed only after an overall evaluation of the scope of supply with all possible strategies. The RFQ should give the potential vendors opportunities to propose several options to help the owner/operator optimize its choice.
When there are separate contracts for component fabrication and installation, the owner/operator should apply special care in assigning responsibilities for ensuring:
— The evaluation of any variance in detail specifications or outline geometry of the replacement components in relation to the interfacing plant systems, including any changes in the static and dynamic loading at the component boundary in relation to the licence requirements and to the integrity of the interfacing SSCs;
— The adequacy of the delivery method and of its location;
— The requirements for equipment protection for intermediary storage, if applicable;
— The piping and nozzle interfaces (end position and finish (bevelled or not), the accuracy of the metrology data, the welding qualifications, the accuracy of the requirements for any thermal treatment to be performed on-site, etc.);
— The adequacy and compliance of the equipment support interfaces (saddles/legs, skirts);
— The cleanliness and hydro test requirements versus the site capability to provide them;
— The adequacy of the manufacturing non-destructive examination report, wherever required;
— The testing requirements;
— The shipment and adequacy of the temporary parts requirements (blind flanges, bolting, etc.).
To facilitate the management of the interfaces, it is strongly advised to place the orders in logical packages (supply, engineering and installation), even if different suppliers are involved.
The owner/operator should give special attention to the installation of critical or sensitive components. These should be in the scope of the main installation contractor or of recognized experienced subcontractors. Sensitive components may include:
— Primary, secondary and auxiliary piping installation (seamless induction bending of large bore pipes, cutting, alignment, welding and non-destructive examination);
— Handling and hoisting of large components (steam generators, vessel head, etc.);
— Execution of the temporary containment building opening, etc.
Although the supply and delivery of large equipment is in most cases the critical factor of the overall scope, delaying the other work orders may induce cascading effects such as encroachments on the critical path and unnecessary overall schedule risks.
In terms of installation issues and threats to the project objectives, among the top LTO implementation risks that may substantially affect project costs and schedule are those related to underestimating installation/construction requirements in a radioactive environment and in older plant settings, with a greatly expanded work force of contractors, possibly inexperienced with work in radioactive environments. Some of the major setbacks encountered in past LTO projects have included:
— Unexpected major scaffolding requirements in older plants lacking access platforms, catwalks, etc.
— Setbacks in first of a kind upgrade designs (if any).
— Engineering errors due to poor configuration management and outdated documentation in older plants and serious unresolved access issues during engineering walkdowns.
— Unpredicted access routing issues for larger upgraded replacement equipment due to new seismic and environmental qualification requirements, higher loading, etc.
— Discovery work for previously undetected, ageing related damage (i.e clogging and corrosion of underground and buried piping).
— Planning and scheduling gaps (i.e. sequence and coordination gaps between operations permit windows, supply and installers).
— Unexpected detail engineering gaps in engineered change packages, resulting in rework and resubmissions for regulatory approvals and a large number of as-built changes, field engineering corrections, deviations and variances.
— Lack of preparation for:
● Radically expanded material handling needs, i.e. increased material routing and poor organization of expanded internal transportation needs (lack of cranes and other material handling equipment, lack of routing plans, interferences, accessibility issues and timely material delivery issues);
● Unexpected requirements for larger decontamination and radioactive waste management facilities;
● Insufficient radiation detection equipment and increased breakdowns of existing equipment because of much heavier use with expanded human resources;
● Unpredicted increase in plant access point requirements;
● Expanded security requirements on-site;
● Underestimated expansion of services in a radioactive environment, such as expanded health physics personnel;
● Expanded requirements for lockers and changing room space, plastic and double plastic suits, tyvek suits, overalls, and greatly expanded specialized laundry facilities for contaminated clothes;
● Underestimated expansion of washrooms, drinking water requirements, food service, parking facilities;
● Underestimated expansion of utilities to support installation (compressed air, gas, service water, steam, power points, etc.);
● Underestimated expansion of lighting facilities to allow work in areas normally without lighting and subjected to high temperatures and a harsh environment during normal operation;
● Underestimated expansion of decontamination areas and facilities for contaminated materials, equipment and tools;
● Expanded warehousing requirements and inventory control issues;
● Expanded need for radiation protection training of contractors and a much greater number of expert escorts in top radioactive areas, etc.
Examples of LTO implementation projects and their status in a number of Member States are presented in Appendix V.