2024 Issue 4

EDN: HXQIBQ

Authors & Affiliations

Ivkov M.I.^{1, 2}, Ahmedov E.G.¹, Anischenko A.M.¹, Gavrilov M.V.^{1, 2}, Tretyakov E.A.¹, Obraztsov E.P.^1
1 St. Petersburg branch JSC Atomenergoproekt – St. Petersburg Design Institute, St. Petersburg, Russia
² Peter the Great St. Petersburg Polytechnic University, St. Petersburg, Russia

Ivkov M.I.^{1, 2} – Design Engineer 3^d Category. Contacts: 82, Savushkina st., St. Petersburg, Russia, 197183. Tel.: +7 (964) 384-37-00; e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it..
Gavrilov M.V.^{1, 2} – Leading Design Engineer.
Akhmedov E.G.¹ – Design Engineer 1^st Category.
Anischenko A.M.¹ – Design Engineer 1^st Category.
Tretyakov E.A.¹ – Chief Specialist.
Obraztsov E.P.¹ – Head of Direction.

Abstract

The results of application of virtual NPP for heat exchange tubes of steam generators rupture analysis is considered in the article. The analysis was carried out to solve the problem of a false start of the CD13 safety function (SF) algorithm “primary-to-secondary circuit leakage” at the Leningrad NPP-2 with a false actuation of reactor trip system. With significant changes in the power level, including a complete shutdown of the reactor, there is a short-term increase in the water level in the steam generator and a decrease in the water level in the pressure compensator, up to violation of safe operation conditions. This may cause the CD13 safety function to be triggered incorrectly. Taking into account the presence of the transient mode of the reactor plant and its duration, it is proposed to introduce a time delay for the activation of SF CD13 by the signal of an increase of the level in the steam generator by 0.25 m. To substantiate this decision and assess its impact on the performance of the main functions of the algorithm, a computational calculation was carried out, at the first stage of which the most conservative location of steam generator heat exchanger tubes rupture and the number of tubes leading to an uncompensated leak were estimated, and at the second stage a variant calculation of the effect of the time delay was carried out. The calculation is carried out using CSS VEB, which is developed on the basis of the Virtual NPP software tool. As a result of analysis, at the first stage it was obtained that the rupture of one heat exchanger tube of the steam generator is uncompensated, and the most conservative location of the leak is the upper row of the tube bundle near the cold collector. Based on the results of the second stage, it can be concluded that the value of the flow rate of the primary circuit coolant does not depend on the choice of the time delay for activation of SF CD13. Thus, in the further stages of modernization, any delay in the range from 0 to 75 seconds can be used.

Keywords
hydrodynamics, leakage, calculation KORSAR/GP, CSS VEB, Virtual NPP, safety functions, safety justification, complex calculation, SimInTech, steam generator leak, NPP modelling

Article Text (PDF, in Russian)

References

UDC 621.039.586

Problems of Atomic Science and Technology. Series: Nuclear and Reactor Constants, 2024, no. 4, 4:16