VVER-1000 Power Monitoring Based on Neutron Detector Signals

V. I. Borysenko1, D. V. Budik2, V. V. Goranchuk1

1Institute for Safety Problems of NPP, NAS of Ukraine,
12, Lysogirska st., Kyiv, 03028, Ukraine
2Severodonetsk Research and Production Association “Impulse”,
2, Peremohy av., Severodonetsk, 09405, Ukraine

DOI: doi.org/10.31717/2311-8253.19.2.1

Abstract

The value of the thermal power of the reactor (TPR) is used in the VVER-1000 control systems in most algorithms for generating control signals, interlocks and protections, and the technical and economic indicators of the power unit are determined by TPR. Plans to increase VVER-1000 TPR to 101.5 % of the nominal, and in the future to 104–107 % of the nominal, require additional research and justification on the accuracy of the determination of TPR. Ways to improve the accuracy of determining TPR based on the signals of VVER-1000 neutron flux monitoring systems were discussed in the article. The main factors affecting the errors in the determination of TPR by the parameters of the neutron flux in the systems are considered: neutron flux monitoring system (NFMS); in-core monitoring system (ICMS). To increase the accuracy of TPR determination in NFMS, a model of automatic correction of the ionization chamber signal is proposed depending on changes in temperature and boric acid concentration in the coolant, the position of the control rods, fuel burnup, etc. The implementation of a model for correcting the signals of NFMS ionization chambers will allow for a wide range of transient operating modes of VVER-1000, including during power maneuvering, to provide regulatory requirements for the error in determining the neutron power of a reactor. Possible additional methods for the determination of TPR, which can be used to determine the weighted average thermal power of the reactor, are proposed. For example, the analysis of changes in the signals of the background conductors of self-powered neutron detectors (SPND), over several VVER-1000 fuel campaigns, shows the fundamental possibility of using the signal of background conductors to determine TPR, along with the signals of the SPND itself. The results of the analysis of the change in the error in determining the weighted average thermal power of the reactor in the case of applying an additional method for determining TPR based on the signals of the background conductors of the SPND are presented.

Keywords: reactor thermal power, neutron flux parameters, self-powered neutron detectors, background conductors, correction model, weight coefficients.

References

4. Dobrotvorskiy A. N. (2017). Razrabotka i obosnovanie metodiki opredeleniya srednevzveshennoy moshchnosti reaktora energoblokov AES s VVER-1000 [Development and substantiation of methods of determination of weighted mean power of NPP units with VVER-1000] (PhD Thesis). Novovoronezh, [s. n.], 191 p. (in Russ.)

5. Bai V. F., Lupishko A. N., Makarov S. V., Bogachek L. N. (2010). Sostoyanie vnutrireaktornogo termokontrolya i analiz osnovnykh teplofizicheskikh kharakteristik RU na blokakh Kalininskoy AES [State of in-core thermal control and analysis of the main thermal and physical characteristics of RP of Kalinin NP]. Proceedings of the 7th International scientific and technical conference “Safety, effectiveness and economics of nuclear power engineering” (Moscow, Russia), p. 228–230. (in Russ.)

7. Stefenson R. (1956). Vvedenie v yadernuyu tekhniku [Introduction to Nuclear Engineering]. Moscow: State Publishing House of Technical and Theoretical Literature, 536 p. (in Russ.)

8. Borysenko V. I. (2018). Vdoskonalennia metodiv i zasobiv operatyvnoho kontroliu ta diahnostyky neitronno-fizychnykh parametriv yadernykh ustanovok [Enhancement of methods and means for operational control and diagnostics of neutronic parameters of nuclear installations] (Dr. thesis). Kyiv, 400 p. (in Ukr.)

9. 4-RNPP. Standard operating procedure of Rivne NPP 4th unit safe operation. (in Russ.)

11. Taylor J. (1997). An Introduction to Error Analysis: The Study of Uncertainties in Physical Measurements. 2nd edition. University Science Books, 448 p.

12. Agapov S. A., Lysenko V. V., Musorin A. I., Tsypin S. G. (1991). Radiatsionnye metody izmereniya parametrov VVER [Radiation methods for measuring VVER parameters]. Moscow: Energoizdat, 136 p. (in Russ.)

13. Lysenko V. V., Musorin A. I., Rymarenko A. I., Tsypin S. G. (1985). Opredelenie yaderno-fizicheskikh i teplofizicheskikh kharakteristik VVER s pomoshch’yu radiatsionnykh izmeriteley [Determination of nuclear-physical and thermophysical characteristics of VVER using radiation meters]. Moscow: Energoizdat, 118 p. (in Russ.)

14. Graham K. F. (1977). 16N Power measuring system. Rep. WCAP-9191. Westinghouse Atomic Power Division, Pittsburgh, USA.

15. DÉCOR system. Direct measurement of the reactor coolant flow based on cross-correlation of Nitrogen 16 time fluctuation. Research and development division EDF preprint, Chatou, France, 1997.

16. WANO (1996). Comanche Peak Steam Electric Station Unit 2. Unidentified Overpower Condition Following a Substantial Loss Of Feedwater Heating. WANO inf. EAR ATL 96–012.

18. Technical report WCAP-13303. Westinghouse Atomic Power Division. Pittsburgh, USA, 1990.

20. Goranchuk V. V. (2019). Monitoryng aktyvnoii zony VVER-1000 metodamy neitronno-shumovoii diagnostyky [VVER-1000 core monitoring by neutron noise diagnostics] (PhD Thesis). Kyiv, 190 p. (in Ukr.)

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Published
2019-08-31

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