DOI: 10.5061/dryad.5tb2rbpc7
title: Behaviour of dissolved inorganic salts in the cooling water of a nuclear power plant open recirculation system and formation of water discharge

description: The main problem in the operation of nuclear power plants is the scale
 formation of mineral impurities in an open recirculating system. However,
 water discharge from an open recirculating system into water bodies can
 lead to changes in the chemical equilibrium of wastewater components and
 requires constant monitoring. The purpose of this study was to analyse the
 behaviour of dissolved inorganic salts in water in an open recirculating
 system during water treatment using the example of the Rivne Nuclear Power
 Plant. Moreover, the analysis impact of their discharge with return water
 in the Styr River. The dissolved inorganic salt concentration has a
 significant impact on the efficiency of the system and the environment of
 an open recirculating system power plant. Altogether, each dissolved
 inorganic salt component was analysed separately using standard
 measurement methods, using statistical methods of data processing, and
 correlation analysis. In addition, the annual discharge of the dissolved
 inorganic salts components was calculated and the amount of discharge was
 assessed for compliance with the maximum discharge limit. Thus, the
 influence of the formation of the dissolved inorganic salts and changes in
 their concentration value during the discharge of returned water into a
 natural water body was analysed.
description: Measurements were performed for the nuclear power plant ORS
 process and return water and water of the Styr River in the RNPP discharge
 area using standard methods. Water pH was measured by potentiometric
 method with a multi-meter І-160. Ca<sup>2+</sup>,
 Mg<sup>2+</sup>, and TH were measured by
 ethylenediaminetetraacetic acid complexometric titration. Flame photometry
 has been used for measuring the concentration of
 Na<sup>+</sup>, K<sup>+</sup>, and silver nitrate
 titrate has been used for measuring the concentration of
 Cl<sup>-</sup>. Method of barium sulfate turbidity has been
 used for measuring the concentration of
 SO<sub>4</sub><sup>2-</sup>. TDS was measured
 using the gravimeter method. TA, and
 ΣHCO<sub>3</sub><sup>-</sup>,
 CO<sub>3</sub><sup>2-</sup> – were measured by
 titration method. The ORS RNPP is designed for operation at COC ranging
 from 1.5 to 7.0. The DIS discharge (D, t) for each component was
 calculated using the formula D = C · F / 1000000 (where: C – is the
 concentration components of DIS in the return cooling water,
 mg/dm<sup>3</sup>; F – is the amount of return cooling water,
 m<sup>3</sup>). The statistical processing of the research
 results involved determining the range of data series (min-max),
 arithmetic mean (M), standard deviation (±SD), Pearson coefficient (r),
 significance of the connection (p) of the appropriate sample, and factor
 analysis of the data was carried out using standard methods of
 mathematical statistics with the software package Minitab software
 (Version 21.4.1, Minitab, LLC).
description: # Behaviour of dissolved inorganic salts in the cooling water of a nuclear
 power plant open recirculation system and formation of water discharge
 [https://doi.org/10.5061/dryad.5tb2rbpc7](https://doi.org/10.5061/dryad.5tb2rbpc7) This dataset contents involved measuring the concentration of DIS: anions HCO3-, CO32-, SO42-, Cl- and cations Ca2+, Mg2+, Na+, and their total parameters of contents total dissolved solids (TDS), total alkalinity (TA), total hardness (TH), and hydrogen pH value. The dissolved inorganic salt concentration has a significant impact on the efficiency of the system and the environment of an open recirculating system power plant. Altogether, each dissolved inorganic salt component was analysed separately using standard measurement methods, using statistical methods of data processing, and correlation analysis. In addition, the annual discharge of the dissolved inorganic salts components was calculated and the amount of discharge was assessed for compliance with the maximum discharge limit. Thus, the influence of the formation of the dissolved inorganic salts and changes in their concentration value during the discharge of returned water into a natural water body was analysed. ## Description of the data and file structure The data is provided in an Excel file. This study involved measuring the concentration of DIS: anions HCO3-, CO32-, SO42-, Cl- and cations Ca2+, Mg2+, Na+, and their total parameters of contents total dissolved solids (TDS), total alkalinity (TA), total hardness (TH), and hydrogen pH value. Measurements were performed for the RNPP ORS process and return water and water of the Styr River in the RNPP discharge area (Fig. 1) using standard methods. Water pH was measured by potentiometric method with a multi-meter І-160. Ca2+, Mg2+, and TH were measured by ethylenediaminetetraacetic acid complexometric titration. Flame photometry has been used for measuring the concentration of Na+, K+, and silver nitrate titrate has been used for measuring the concentration of Cl-. Method of barium sulfate turbidity has been used for measuring the concentration of SO42-. TDS was measured using the gravimeter method. TA, and ΣHCO3-, CO32- – were measured by titration method. Sheet 1 contains all the input data of the control results. Sheet 2 contains the calculated values of the maximum permissible discharge. Sheet 3 contains the data for calculating correlation dependencies. Sheet 4 contains the distribution of the ratio of soluble components. The authors do not duplicate the figures and tables in this file and indicate them in the article. ## Sharing/Access information Data are contained within the Paper. Information about the influence of substances that were studied in the article is partially presented and is publicly available in «Reports on the assessment of the impact of non-radiation factors on the environment of the Rivne NPP SE «NAEK Energoatom» (Ukraine) for the year 2022». Water treatment of the ORS cooling water of the RNPP was carried out by lime softening, followed by stabilization treatment with sulfuric and 1-hydroxyethane-1,1-diphosphonic acids (HEDP). The raw water requirements for the cooling water circuit for the ORS RNPP are approximately 6000 m^3/hr for different operating modes, and the water is discharged into the Styr River at a constant flow rate of approximately 1000 m3/h. The ORS RNPP is designed for operation at COC ranging from 1.5 to 7.0. The DIS discharge (D, t) for each component was calculated using formula (14), and the annual discharge was calculated according to the annual amount of discharged cooling water. D = C · F / 1000000 where: C is the concentration components of DIS in the return cooling water, mg/dm^3; and F is the amount of return cooling water, m^3. To assess the discharge quality indicators, the regulated content values of DIS in the cooling water of the RNPP ORS [1] and established by foreign organisations for ORS NPPs [2,3,4] were used. To assess the return water quality using the regulated typical LV according to [5] and regulated LV for RNPP according to [3]. ## References \[1] Good Practices for Water Quality Management in Research Reactors and Spent Fuel Storage Facilities, IAEA Nuclear Energy Series No. NP-T-5.2, IAEA, Vienna (2011). \[2] Permit for special water use of SS Rivne NPP No. 53/RV/49d-20 2020 URL Retrieved from [https://e-services.davr.gov.ua/](https://e-services.davr.gov.ua/) (in Ukrainian) \[3] SOU NAEK 067:2013. Management of chemical technologies. The water-chemical mode of the technical water supply system of responsible consumers of NPP with VVER. (in Ukrainian) \[4] EPRI. Open Cooling Water Chemistry Guidelin 2012, EPRI report 1025318, hereinafter, Guidelines. \[5] Drum Screen Filtration of Cooling Water in Fossil-Fired and Nuclear Power Plants: The Electricite de France (EDF) Experience Program 2012, Aquatic Resource Protection 239.