Canadian SCWR concept

The Canadian SCWR concept is a pressure-tube type of concept. It adopts the direct cycle, which includes a 2540-MWth core that receives feed water at 315°C and 1176 kg/s and generates supercritical steam at 625°C and 25 MPa. The cycle includes steam reheat using a moisture separator reheater (MSR) between the IP turbine and LP turbine. The MSR separates the moisture from the steam and reheats the steam to ensure an acceptable moisture level at the outlet of the LP turbine. Four LP condensate heaters are included in the cycle as well as a deaerator and four HP feed-water heaters. The gross electrical output is calculated as 1255 MWg, giving a gross thermal efficiency of 49.4%. A schematic diagram of the direct cycle is shown in Fig. 8.4 (Zhou, 2009). 

The safety approach adopted for the Canadian SCWR concept follows those of advanced reactors in that multiple levels of independent and diverse safety systems... 

Although two independent trains of ICs are considered as the reference configuration for the Canadian SCWR concept, the required capacity of the ICs varies as the reactor is cooled to prevent mmecessaiily rapid cooling rates. The current two-train configuration may not allow plant operators to adequately control the cool-down rate and would require further subdivision into four independent trains, with one train attached to each of the reactor outlets. Details on the configuration will be established in future design phases. 

The modified sliding pressure staitup as proposed by Yi et al. (2005) can be adapted to the proposed operating conditions in the Canadian SCWR concept. To provide a starting point for future analysis of critical performance characteristics (eg, fuel cladding temperatures and thermal-hydraulic and neutron stabilities), reference operating conditions (eg, flow rates, reactor power levels, and mechanical equipment configurations) have been selected. 

M. Yetisir, M. Gaudet, D. Rhodes, Development and integration of Canadian SCWR concept with counter-flow fuel assembly, in ISSCWR-6 The 6th International Symposium on Supercritical Water-Cooled Reactors, March 3—7, 2013, CGNPC, Shenzhen, Guangdong, China. China, 2013. Paper ISSCWR6-13059. 

W.G. Cook, R.P. Olive, Corrosion product deposition on two possible fuel geometries in the Canadian-SCWR concept, in 3rd China-Canada Joint Workshop on Supercritical Water-Cooled Reactors (CCSC-2012), Xi an, China, April 18-20, 2012. 

The Canadian SCWR core concept is illustrated in Fig. 8.5. It consists of a pressurized inlet plenum, an LP calandria vessel that contains heavy water moderator, and 336 fuel channels that are attached to a common outlet header. A counterflow fuel channel is adopted to position the inlet and outlet piping above the reactor core so that a complete break of either an inlet pipe or an oudet pipe will not result in an immediate loss of coolant at the reactor core. A nonfuel central flow channel is located at the center of the fuel channel to increase neutron moderation close to the inner fuel rings. This feature results in reasonably uniform radial power distributions across the fuel channel as well as a desirable negative coolant void reactivity throughout the bum-up cycle. 

Figure 4.2 Schematic of the Canadian SCWR core concept [6]. 

Currently, only austenitic stainless steels and some nickel-based alloys can meet these requirements. Table 4.1 lists candidate fuel cladding materials that have been considered for the Canadian, EU, and Japanese SCWR concepts. 

Table 4.1 Compositions of candidate fuel cladding alloys for the Canadian SCWR, EU HPLWR, and Japanese JSCWR concepts... 

SCWR NPP (one of Canadian concepts, ie, pressure channel reactor) thermal neutron spectrum moderator—D2O reactor coolant—H2O P = 25 MPa (Pq. = 22.064 MPa) and Pin = 350-C and Pout = 625°C (P = 374°C) direct cycle, ie, single loop supercritical pressure Rankine power cycle with single steam reheat—primary steam (turbine inlet) Pj = 25 MPa (P = 22.064 MPa) and P = 625°C (Per = 374°C) secondary steam Pi = 5.7 MPa (Psat = 252°C) and Pi = 625°C possible backup—indirect supercritical pressure Rankine steam cycle with single steam reheat (superheat) 45-50... 

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