NPP thermal power uprate is relevant for Ukraine

Currently, more than 50% of electricity is produced by nuclear power plants (NPPs) in Ukraine. Effective use of existing power units for the country is a priority since it is economically justified and significantly less expensive than the construction of new ones. With the purpose of more efficient operation of the national NPPs, following up-to-date world trends, Ukraine considers the possibility of thermal power uprate for Ukrainian NPPs. The editorial board discussed with Viktor Shenderovych, an honored worker of Ukraine’s nuclear industry, how reasonable power uprate is for our country, what the advantages are and if there are any risks.

Viktor Shenderovych

–  Mr. Shenderovych,  could you tell what is NPP thermal power uprate? What is the purpose of its implementation?

– The economy of nuclear energy is one of the important factors in the development of this industry. At the same time, one of the priority areas is to increase the NPP design thermal power by thermal power uprate of reactors and, correspondingly, electric power uprate of power units. Electric power uprate in its turn leads to increase in electricity supply and, correspondingly, increase in NPP economic indicators.

Power uprate measures are implemented in different countries for power units of various types and are a priority in terms of achieving the best economic indicators.

– Is this a priority for Ukraine?

– I think it is. Since it will significantly increase the electricity supply from NPPs. For VVER-1000 power units, this is about additional 300 million kW/h per year. Considering a relatively high level and reliability of electricity supply from Ukrainian NPPs, this concept will potentially increase general reliability of power supply.

Power uprate is one of the most efficient ways of obtaining additional electric power. At the same time, it should be noted that the first priority of course is lifetime extension of operating power units. Activities in this area are actively performed by the Energoatom Company. Power uprate activities, in terms of the required measures and possible timeframes, should be interrelated with lifetime extension activities.

– How NPP thermal power uprate is implemented? Is there a difference between its implementation at VVER-1000 and VVER-440 power units?

– Thermal and, accordingly, electric power of operating units is increased through the use of internal design margins of equipment and systems and involves required upgrades of certain equipment and improvement of monitoring and control systems. This necessarily involves a set of justifications, including nuclear and radiation safety justifications, required to obtain positive conclusions of the nuclear and radiation safety review.

In principle, there is no difference in the implementation of this concept for VVER-1000 and VVER-440 power units, taking into account that available internal margins of reactors and measures for specific equipment and systems are different for the specified power units, which is reflected in the scope of necessary measures.

 – At U.S. NPPs, thermal power uprate has been implemented at almost all power units of the country. Is this concept popular in Europe?

– Indeed, the majority of U.S. NPPs have implemented design power uprate of different power units. At the same time, PWR units are in principle comparable with VVER.

In Europe, power uprate activities are also a priority. At most operating PWRs (900 mW) in France, their power was increased to 103%. The French plan is 7% power uprate of 1300 mW power units.

At European NPPs with VVER, power uprate was implemented in Finland, Hungary and the Czech Republic. For example, the Finnish Loviisa NPP (VVER-440) increased power by 11%, the Hungarian Paks NPP (VVER-440) by 10% and the Czech Temelin NPP (VVER-1000) by 4%.

– In the Russian Federation, there is a considerable number of power units whose design is similar to those in Ukraine. Does the Russian Federation increase thermal power of VVER-1000 and VVER-440?

-Yes, it does. At the Kalinin and Rostov NPPs with VVER-1000, power has already been increased by 4%, and future plans include 7% increase. At the same time, activities are underway for possible power uprate to 10%. At the Kola NPP with VVER-440, power was increased by 7%.

– What is the cost of power uprate for the national power plants?

– Presently, the Energoatom Company, involving design organizations, performs feasibility analysis to assess the required costs and economic efficiency of power uprate.

First, these activities were performed for pilot power units: ZNPP-6 with VVER-1000/320 and RNPP-2 with VVER-440. The results of these evaluations for ZNPP-6 show that 104% power uprate for one VVER-1000/320 unit requires 300-400 million hryvnias (including upgrades of the turbine and generator). Additional generation of electricity is about 9 billion kW/h and additional income from electricity sale (in current prices) is 4.7 billion hryvnias. These data refer to the whole period of operation.

The analysis of economic efficiency gives grounds to consider that power uprate is feasible from the investment point of view and recommended under existing economic conditions.

The discounted payback period (taking into account change in money value over time) is about 7-8 years. This of course is effective considering long operating time (lifetime extension by 20 years).

These data give an idea of how efficient this concept is. For specific power units, all performance indicators require clarification taking into account specific features of different NPPs and power units.

– Where to get this money?

 – It is expected that the Energoatom Company will fund the activities. You may contact them for more precise information.

I would like to focus your attention on the fact that more justified pricing policy in the industry will contribute to the Energoatom Company’s financial capabilities for implementation of the activities.

– In the framework of trial operation, thermal power was first increased in Ukraine to 101.5% in November 2016 at SUNPP-1. Was this experience successful?

 – The experience of power uprate to 101.5% at SUNPP-1 was successful and did not require any additional measures for further project implementation.

– Which power units are the next for power uprate to 101.5%?

– Tentatively, in 2018 this mode is to be implemented at SUNPP-2, then at VVER-1000/320 power units (first, at pilot ZNPP-2, KhNPP-1, and RNPP-3 in 2018). Power uprate to 101.5% is considered as the first stage of this concept implementation, whose results will allow more justified transfer to the next stage: VVER-1000 power uprate to 104%.

– At what national units power uprate to 104%, 105-110% and 108% is planned?

– In compliance with the current plans, assessments and activities carried out to justify the possibility of power uprate, taking into account international experience in this area, 104% power uprate is planned for VVER-1000 units with TVEL fuel and 108% power uprate is planned for VVER-440 units. All the prerequisites for successful implementation of this stage are available. However, it is required to perform a set of upgrades on equipment and systems. In addition, nuclear and radiation safety justification documentation should be developed.

An important factor influencing power uprate conditions is the state of nuclear fuel. Since the use of Westinghouse fuel is planned at VVER-1000 power units, the operating organization initiated cooperation with the Westinghouse Company on power uprate taking into account the use of TVS-WR fuel assemblies.

At the initial stage, the maximum possible level of thermal power uprate (in a range of 105-110%) and accordingly electric power uprate, as well as the scope of necessary upgrades, should be specified.

Pilot power uprate activities with Westinghouse fuel are expected at SUNPP-3; they are likely to be combined with lifetime extension activities. Based on the results, the next stages will be specified, necessary measures will be determined, and the implementation cost will be assessed. Tentative period of implementation is 2020.

In accordance with the Energoatom Company’s plans, pilot power units were also identified for 104% and 108% power uprate. These are ZNPP-6 and RNPP-2, respectively. Expected periods of trial operation: ZNPP-6 – 2018; RNPP-2 – 2020-2021.

The power uprate at other power units will be based on the results obtained for the pilot units approximately until 2020-2022.

– Is power uprate safe in the context of ensuring nuclear and radiation safety?

The experience of preliminary studies, as well as the specific experience on power uprate of operating VVER power units in other countries, gives sufficient grounds to talk about the possibility of their safe operation taking into account current requirements for nuclear and radiation safety.

At the same time, I would like to note that an obligatory condition for this activity is developing all safety justification documents and obtaining a positive conclusion of the regulatory body on nuclear and radiation safety.

As for the impact on the environment, there will be no changes. Some increase in thermal impact due to greater heat removal from turbine condensers is possible but the level of such impact is negligible. Editorial Board