R2.01/06 PART B Development of modernisation measures of primary and secondary water chemistry monitoring systemsfor unit 1 and 2 of Kalinin NPP

Appropriate water chemistry of both primary (nuclear) and secondary (non-nuclear) cooling circuits of a nuclear power plant is necessary to maintain safe, reliable and economical operation of the plant. Among others, it helps to

• Minimize radioactive deposits on internal surfaces of primary circuit components decreasing the collective dose rate of the plant personnel;
• Minimize deposit creation on the heat-exchanging surfaces optimizing the heat transfer;
• Minimize corrosive damage of primary and secondary circuit components;
• Maintain integrity of the fuel cladding.

In order to keep the water chemistry appropriate, the related chemical parameters (pH, conductivity, impurity concentration) at specific points have to be carefully monitored.

In the past, water chemistry at Russian NPPs had been monitored mostly “manually”, i.e. by laboratory analysis of manually taken samples. The available on-line water chemistry monitoring equipment had been obsolete and not compliant with up-to-date technology. Being aware of the persisting gaps in the NPP water chemistry control against the best international practice, the Concern Rosenergoatom asked the European Commission for support in this area. To provide the assistance, the EC established the R2.01/06 TACIS project.

The project was implemented within two separate contracts: (1) this global price contract 172020 concluded with a Russia-based Director of Experiments (DoE) EREC Institute in Elektrogorsk, Russia, and (2) another, fee-based contract 132487 concluded with an EU-based consultant, Chemcomex Prague, as described in a separate summary. The overall project management was the responsibility of the EU-based consultant, Chemcomex, a.s.

The general objective of the R2.01/06 project had been to support the Concern Rosenergoatom in monitoring the water chemistry at VVER-1000 power plants and to modernize it by taking into account the international experience and best practice.

The specific objective of the 172020 contract had been to experimentally verify adequacy of the data acquisition and processing system CHEMIS, as proposed and delivered by the consultant within the 132487 contract, to acquire, store, evaluate and display the water chemistry data provided by a standard secondary circuit water chemistry monitoring system of a VVER-1000 NPP. In particular, the experiments were supposed to verify:

• Functionality of data transfer from the on-line analysers of the secondary circuit chemistry into the CHEMIS system
• Key software algorithms on data compression and evaluation of chemical parameters
• Functionality of individual software modules of the CHEMIS system

The verification experiments were performed at the V-3 experimental facility at the EREC Elektrogorsk. The V-3 facility is a large-scale model of the VVER-1000 secondary circuit equipped for investigations of the VVER-1000 secondary water chemistry as well as its automated monitoring and control systems (see the Annex1).
The experiments were performed in three stages as follows:

Establishment and verification of data communication between the CHEMIS system server and the V-3 facility control system server
Verification of functionality of CHEMIS software modules
Comprehensive testing of the CHEMIS system at the V-3 facility
The first two stages were performed by the consultant in cooperation with the EREC experts from July 2010 to January 2011 and from April to September 2011 respectively.
The stage 3 was performed by the DoE under the supervision of the consultant and EC from November 2011 to January 2012. In November 2011, the programme of experiments was discussed and agreed between the consultant and DoE. The experiments themselves started on 13 December 2011, but had to be interrupted due to V-3 facility leaks and control system problems. The experiments were then repeated and finalized in the period of January 16 - 19, 2012. The preparation of V-3 experimental facility for the experiments (filling, flushing, heating up and establishing standard water chemistry) was done by the DoE on January 16, 2012. Water chemistry transients during the V-3 facility start-up were monitored and recorded using the CHEMIS system as an initial stage of the verification experiments. The main part of verification experiments started on 17 January 2012. The consultant experts supervised the experiment progress, monitored the V-3 process parameters and proper operation of the CHEMIS system. The experiments were successfully completed on 19 January 2012 and recorded in the DoE Qualification Report. The experiments verified:

full compliance of the water chemistry data obtained from the CHEMIS system with the actual water chemistry established and monitored by the V-3 facility systems;
reliability of the consultant’s CHEMIS system in real-time data collection and subsequent analysis;
easy and rapid commissioning of the CHEMIS system when connected to an existing automated control system ;
simple adaptability of the of CHEMIS system interface to the requirements of the system user.

Conclusions
The qualification tests at the V-3 EREC facility showed that the design of secondary water chemistry monitoring system for units 1 and 2 of the Kalinin NPP, as proposed and developed by the project consultant, Chemcomex a.s., in the frame of the 132487 contract, was compliant with the VVER-1000 NPP requirements and could be accepted without any modifications.
It was also concluded that the CHEMIS software was eligible for data acquisition and processing in water chemistry monitoring systems at Russian NPP units with VVER-1000 reactors

Annex1: Stereometric model of the V-3 experimental facility

Legend:
1 — deaerator
2 — throttling and cooling module
3 — steam generator
4 — low pressure feed heaters
5 — condenser
6 — high pressure feed heaters
7 — condensate clean-up system
8 — condensate pumps
9 — feed pumps