Water circuits, power station

The importance of chemistry to the nuclear power industry is now well recognized. Chemical control in water circuits is an accepted part of the operating requirements of nuclear generating stations, as it is for modern fossil-fired stations. While there have been major advances in knowledge of the chemistry of aqueous systems at temperatures above lOQoC, there is still a need for further work. As we improve our understanding of thermodynamics and kinetics of solid-aqueous reactions and the effect of radiation on them, we can expect further advances in controlling radiation fields in reactor circuits and in minimizing iron deposition in GS plants. 

FIGURE 16.3. Simplified flow sheet of a power station cooling water circuit using chemical additives... 

Two-circuit reactor plant (RP) with a vessel-type pressurized water reactor is used for floating power unit of nuclear head and power station. Basic RP components reactor, steam generators and primary coolant pumps are incorporated by pressure nozzles in a compact steam-generating block. KLT-40C RP characteristics are given in Table 1. 

The PWR has three main water circuits. The first is the primary circuit that carries heat energy from the nuclear reactor to the steam generators. The water is maintained at a pressure of sl50bar and an operating temperature of s573 K. Since the primary circuit is a closed loop, it is the only water circuit in the power station that contains radioactivity. The second water circuit is the water-steam cycle, and the final circuit is the water cooling system, which dissipates excess heat. 

In a nuclear power station, there are several ion-exchange systems for water clean-up. In a typical BWR there are purification circuits after the steam condenser, in a small stream from the reactor vessel and for the water in the fuel storage pool. In a pressurized water reactor (PWR), part of the coolant in the primary circuit is withdrawn, cooled, and pumped through an ion-exchange filter. As indicated by the word filter, these ion exchangers are also used to remove particles from the liquids. They often consist of mixed cation and anion exchangers that are very finely ground bead sizes of 400 mesh are common. 

Schematic sketch of nuclear power station with a pressurized water reactor (1) reactor, (2) steam generator, (3) main pump for primary cooling circuit, (4) turbines/generator, (5) steam drum,...

Lambert, I., Brunet, S., Roy, M., Gerlinger, Ph. Chemical decontamination process for PWR primary circuits. Proc. 5. BNES Conf Water Chemistry of Nuclear Reactor Systems, Bournemouth, UK, 1989, Vol. 1, p. 321—322 LeSurf J. E. Control of radiation exposures at CANDU nuclear power stations. J. British Nucl. Energy Soc. 16, (1), 53—61 (1977)... 

Demineralised Water for Power Station Auxiliary Cooling Circuits Corrosion Australasia 16, (1) Feb. 1991,... 

Fig 117 The steam-water circuit of a conventional power station. 

On the low pressure side 90/10 cupronickel was used to tube Nos 1 and 2 LP heater, and the deaerator vent condenser, as at low temperatures of operation no serious corrosion was expected on the steam side even In the presence of oxygen. On the water side most of the released corrosion products will be removed by the full flow Ion exchange treatment given by Powdex resin Interposed beyond the second LP heater. Typical analysis for water which has been given this treatment are 5 ppb maximum for metals normally encountered In feed-water circuits. Unfortunately It Is clear from power station experience that a significant pick-up of corrosion products on the water side takes place In the high pressure feed heaters downstream of the clean-up plant. 

Conventionally In water reactor Installations, primary circuits and condensate streams were treated by means of Ion exchange units, with or without filters. The resins were in bead form, and could be regenerated their operating temperature was limited to about 50°C. At the time the decision had to be taken for the Wlnfrlth SGHWR, preliminary Information on the use of throwaway powdered resin systems at temperatures of about 100°C in conventional power stations was becoming available (ref. 7). These systems could... 

Scenario Damage to culvert The main event selected for illustration in this paper is Damage to culvert/joint conduit of electric power, ICT, and water mains . This event is based on an actual event that occurred in Oslo on November 27th, 2007 An entrepreneur unwarily broke a cable when digging a ditch, and the cable break led to short circuit and fire at the Oslo S railway station (Oslo Central Station), further paralyzing the region s rail traffic and transportation systems for 20 hours, and the internet systems for about 10 hours (DSB 2008). 

---