Abstracts - VGB PowerTech Journal 5/2021

Numbers abour nuclear power: 2020

Christopher Weßelmann

The use and expansion of nuclear energy continues to be characterised on the one hand by a geographically clearly shifted trend in its expansion from its regions of origin, North America and Europe, to the new players in Asia. On the other hand, it can be seen that both China and Russia are entering the global nuclear energy market as exporters of complete concepts. [more...]

The World’s first power plant to produce 400 billion kilowatt hours

Matthias Domnick, Sebastian von Gehlen, Stephan Kunze, Gerald Schäufele, Dietmar Schütze and Ralf Südfeld

When it first synchronised with the power distribution network at 14:11 hrs on 5 September 1984, Grohnde nuclear power plant (KWG) started to write its own success story. Since it was first commissioned, the ­pressurised water reactor has eight times been World Champion in annual electricity generation. Even today, Grohnde NPP still produces a good 12 % of the electricity generated in Lower Saxony, thereby helping to stabilize the electricity supply in Germany. And yet another record was recently added to this ­impressive list. On 7 February 2021, KWG was the first power plant unit in the world to produce its 400 billionth kilowatt hour of electricity. No other nuclear power plant unit in the world has produced more electricity. This amount of electricity would have supplied the whole of Germany for nine months (based on the 2019 figure of 512 TWh).

Quo vadis, grid stability?
Challenges increase as generation portfolio changes

Kai Kosowski and Frank Diercks

The power generation portfolio in the German high voltage transmission and distribution system has been constantly changing since 2011. After several decades with relatively constant segmentation into base-, medium- and peak-load and a power plant park designed accordingly for these purposes, significant changes have occurred in the last 10 years. As an important result of the so-called Energiewende , starting in 2011 with the shutdown of the first German nuclear power plants (NPP) after the reactor accident in Fukushima, the last NPPs will go eventually offline by the end of 2022. The Coal Phase-Out Act of August 8th, 2020, a far-reaching edit with significance for the energy industry in Germany, requires the shutdown of all coal-fired power plants by 2038 at the latest. From this point in time at the latest, there will be no large, inductive power plants for generating base load in the German power plant park.

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Development of Safety-related residual heat removal chains from german technology pressure water reactors (light and heavy water)

Franz Stuhlmüller and Rafael Macián-Juan

The Nuclear Power Plants (NPPs) with Pressure Water Reactor for enriched fuel (PLWR, Pressurized Light Water Reactor) and for natural uranium (PHWR, Pressurized Heavy Water Reactor), developed in Germany, are largely identical in their basic design. However, there is a striking difference in the scope of the main reactor systems. While in PLWR these only consist of Reactor and Reactor Coolant System including Pressurizer and Pressurizer Relief Tank, in PHWR the Moderator System is added. In power operation of a PLWR, the entire thermal reactor power is transferred to the water/steam cycle via the Steam Generators. In PHWR, on the other hand, part of the power (approx. 10 %) has to be removed - at a lower temperature level - from the moderator, which is spatially separated from the main reactor coolant within the Reactor Pressure Vessel, but is kept at the same pressure via function-related compensating openings. This portion of power is used to preheat the feed water before it enters the Steam Generators. The Moderator System installed for this purpose can also be used in a second function as the inner link in the Residual Heat Removal Chain (RHRC) for cooling the reactor after it has been switched off. In PLWR the analog system is operated exclusively for the removal of residual heat from the reactor and, if necessary, the fuel pool. In the following, the development of the RHRC of both NPP lines is shown and the main differences between both NPP-types in this regard are explained by comparing the most recently erected plants, DWR 1300 MW (KONVOI) and Atucha 2.

Demand analysis of nuclear power technology in China: opportunities for foreign nuclear power companies

Hong Xu, Tao Tang and Baorui Zhang

China has the largest number of nuclear power plant (NPP) units under construction or planned in the world, which shows the promising potential business opportunities of its nuclear power market. Simultaneously, it has a complete nuclear industry chain with hundreds of related companies/organizations. The huge market of nuclear power is attractive to foreign nuclear power companies. China has a good environment for international cooperation. But the problem is how to clarify the possible demand in traditional sub-fields of nuclear power technology and different subsidiaries for cooperation. Due to the huge work of one-by-one demand analysis and the uncertainty of the academic research level evaluation of the subsidiaries from different organizations, this article presents a statistical method based on the evaluation of the China Nuclear Energy Association (CNEA) experts and related reports. The conclusion of this article can be used as a reference for international cooperation in the nuclear power community.

Error reduction in radioactivity calculation for retired nuclear power plant considering detailed plant-specific operation history

Young Jae Maeng and Chan Hyeong Kim

Accurate estimation of radioactivity distribution at a retired nuclear power plant (NPP) is important for establishing a reasonable dismantling strategy and expecting radioactive waste disposal costs for decommissioning. The calculation of activity requires several input parameters, including target nuclides, products, irradiation history, and the neutron flux. To our knowledge, in most cases, existing radioactivity calculations for a retired NPP do not fully consider the detailed plant-specific operation history, including cycle-specific neutron flux data, which may lead to significant errors. In this study, we investigated the effect of using detailed history on activity calculation. We calculated the activities of samples in six surveillance capsules of the Kori 1 NPP, using two approaches: (1) considering and (2) not considering detailed history. Activities calculated using these two approaches were compared with measured values to determine the improvement in accuracy. The findings show that accuracy is significantly improved when the detailed history is considered. The average error of the calculated activities was reduced from 12 %, 41 %, and 30 % to 5 %, 9 %, and 9 % for 63Cu(n,)60Co, 54Fe(n,p)54Mn, and 58Ni(n,p)58Co reactions, respectively. The results of this study strongly suggest that considering the detailed plant-specific operation history is necessary in activity calculation for a retired NPP.

Forum Energy Supply: Europe on the road to a main disaster
After the lockdown, a blackout?

Herbert Saurugg

The European power supply system is undergoing a fundamental upheaval where, above all, “many cooks spoil the broth” applies. This is because there is no overall systemic coordination and approach. Each member country is making its own energy transition in different directions and there is hardly any coordinated approach recognizable. In addition, fundamental physical and technical conditions are being ignored and replaced by wishful thinking, which is bound to lead to disaster. This is because the power supply system obeys purely physical laws. We still have the opportunity to leave this fatal path.

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Operating experience with nuclear power plants 2020

VGB PowerTech

The VGB Technical Committee “Nuclear Plant Operation” has been exchanging operating experience about nuclear power plants for more than 30 years. Plant operators from several European countries are participating in the exchange. A report is given on the operating results achieved in 2020, events important to plant safety, special and relevant repair, and retrofit measures.

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