[en] This article presents the benefits of increasing power for the economic aspects and for the revision and updating of the installation. (Author)

[en] This report analyses the different risk situations which may arise during refuelling outage at Cofrentes NPP. The most critical situations are determined in terms of the small amount of coolant available and the lowest number of heat removal and water make-up systems available. The available times before the boiling point of the coolant is reached and the subsequent moment when the fuel elements are left uncovered in the event of the failure of the normal heat removal functions are determined. The analysis identifies the alternative systems which can be used besides those required by the technical specification and their capacity for residual heat removal and coolant make-up functions. (Author)

[en] Hydrogen chemistry is the solution adopted by Cofrentes NPP (BWR,GE, 990 MWe) to prevent and mitigate intergranular stress corrosion cracking (IGSCC) of the austenitic stainless steels from which the reactor vessel recirculation loops and internals are formed. The effectiveness of this method has been verified by means of specific tests and measurements taken in the different BWR-type plants where it has been implemented. It is based on injecting H₂ into the feedwater flow to the reactor so as to adjust and reduce the O₂ levels in the vessel. This paper shows the characteristics of H₂ and O₂ injection systems for Cofrentes NPP and of their associated subsystems for injection control and H₂/O₂ analysers in the off-gas system, as well as for the reduction of active cobalt and dose rates reduction by injecting zinc. (Author) 5 refs

[en] The need to increase the installed electric capacity and maximize financial returns were the two fundamental reasons for creating an Electric Power Increase programme at Cofrentes. The first phase consisted of licensing and implementing in 1988 a 2% power increase to 990 MWe. Studies for an additional increase of 30 MWe, up to 104.3% nominal thermal power, were presented that year to the Consejo de Seguridad Nuclear (Spanish Nuclear Safety Council) and the Ministry of Industry, and are pending evaluation. This article analyses, from the viewpoint of Plant systems, the impact of a power increase of up to 104.3%, the implications and considerations to be taken into account in future equipment modifications or replacements for a planned increase of up to 115% nominal power, and the effect of a power increase due to the thermal efficiency of the equipment. The analysis also considers the experience of similar plants which have created programmes with these characteristics. (Author)

[en] The experience which this document wants to present, describes the work being developed by IBERDROLA Ingenieria y Construccion, for the Laguna Verde plant in Mexico, owned by the Federal Electricity Commission (CFE). This generation plant consists of two light boiling water type units (BWR) design by General Electric in the 80's. The objective of this project is to perform the modifications on the thermal cycle of the plant required by an Extended Power Up-rate, to achieve a safe and reliable operation of the plant at 120% of its original thermal power, whilst upgrading and renovating plant equipment and installations to achieve a license renewal from 40 to 60 years of operation The consortium formed in 97% by IBERDROLA Ingenieria y Construccion SAU and in 3% by ALSTOM Mexicana, S.A. de CV, was awarded the contract in an international bid, competing against General Electric and Siemens. The project began in March 2007 and is scheduled to finalize in December 2010. At this point the work carried out include modifications of the main condenser replacement, moisture separator reheaters (MSR's) and feedwater heaters no. 5 and 6 in the two units, therefore having executed two out of four scheduled outages. The scope, development and organization of this project, whose basic elements include the design, engineering, training, supply of equipment, dismantling, installation, testing, commissioning, treatment and delivery of radioactive waste generated during the project implementation to CFE, is aimed to ensure a safe and reliable operation of the plant under the new conditions of increased thermal power of the reactor, with a thermal cycle optimized so that the gross power of the generator increase from the current 686.7 MWe to a value of 817.1 MWe in both units. An Extended Power Up-rate means an opportunity to modernize equipments, to improve maintenance, to get a better plant knowledge and to motivate the employees facing a challenging project. This project, being the biggest foreign nuclear contract awarded to a Spanish company, demonstrates our ability to handle challenging projects which have impact on countries' growth, both in the field of productivity and technical development. It also demonstrates client's commitment to the long term development of nuclear energy, a clean and non contaminating energy, free of CO₂ emissions. Other advantages of the EPU: - Generates significant economic value in the short term, with a very competitive marginal price per kWh in comparison with other technological alternatives - Involves a comprehensive review of plant design, which allows to evaluate and confirm margins in front of the regulatory organism The following are some of the key success factors of an outage: - Implementation of lessons learned during the previous outage; - Detailed and realistic planning of the modification packages activities; - Establishment of contingency plans; - Coordination between the customer and IBERDROLA teams; - Maximization of pre outage work during operation: Planning all work that can be done during operation; - Re-engineering of equipment installation procedures, based on lessons learned. (authors)