1. Secondary circuit heat-exchange equipment efficiency improvement
7-th International Scientific and Technical Conference «Safety, efficiency and economics of nuclear power» MNTK-2010
Moscow, May 2010
JSC «Concern Rosenergoatom»
Secondary circuit heat-exchange equipment
efficiency improvement
A.A.Avdeev
Director General, Doctor of Technical Sciences
Open joint-stock company
«All-Russian Research and Design-Engineering Institute of nuclear power machine building» JSC «VNIIAM»

2. Today, technical problems center of gravity is in the turbine hall
Efficiency
Reactor island
Turbine island
>98%
33÷36%
Almost all heat released in the core is supplied to secondary circuit
Only the third part of heat is converted to electric power
Today, technical problems center of gravity is in the turbine hall

3. Economics evaluation
How much higher can the cost of the turbine plant with efficiency increased
by 1% be?
Unit 1200 МW; Efficiency э = 36%
Additional production: 33,3 МW
э = 37%
Capital expenditure to produce this power
3000 €/kW * 33,3 МW = 100 mln.€
Account is not taken of «small things»: fuel saving, specific operating expenses, etc.
Note: cost of 1000 МW turbine (Kharkov): about 80 mln. €
cost of 1200 МW turbine (St.Pb): about 100 mln. €
It is more profitable to pay twice more for the turbine with efficiency increased by 1%.
The turbine plant efficiency is determined by all the kit of turbine hall components.

4. Rated (calculated) value
Effect of turbine plant К /1500 parameters on electric power underproduction
It no.
Name of parameter
Rated (calculated) value
Deviation
Loss of power, МW 1.
Live steam degree of dryness, %
99,5
-0,5
-3,5 2.
Spent steam pressure kgf/cm2, (kPa)
0,05 (5,0)
+0,01 (1,0)
-11,5 3.
Pressure losses in steam-admission devices (SCV), %
3÷4
+1,0
-1,5÷-2,0 4.
Pressure losses in intermediate overheating components (MSR), %
7,0
-2,0 5.
Feed water final temperature, С
220,0
-5,0
-3,0 6.
Steam underheating, in MSR I-st and II-d stages, С
25,0
+5,0
-0,5÷-1,0
Total:
23 МW

5. Parameters optimization
The optimization of turbine plant parameters requires:
Unit heat losses tests within the range of loads from 75 to100% from rated power;
condenser thermal tests with building of vacuum dependency on cooling water flow rate and temperature;
turbine power experimental corrections in case of changes in condenser spent steam pressure.
Heat losses tests are conducted according to the first category of complexity with arranging additional inserts and applying the state-of-the-art fleet of high accuracy instruments.

6. Pressure of the used steam in the condenser
Test results
1. Normalization
Pressure of the used steam in the condenser
Unit power
Electric power of NPP unit depending on the temperature of the incoming cooling water (under nominal power)
2. Identification and elimination of losses
3. Assessment of upgrading results

7. NPP (Power Unit) turbine plant tests
Power Unit No.
Turbine
Test year and performer
Type
Manufacturer
Leningrad NPP, Unit1
К /3000
Turboatom
1976 ; ОRGRES, Ural Division
ChNPP, Unit 1
1980; ОRGRES, South Division
Kalinine NPP, Unit 1
К /1500
1985; ОRGRES, Мoscow
Kalinine NPP, Unit 2
1986; ОRGRES, Моscow
VVER-1000 Power Units with К / type turbines (Тurboatom, with basement-type condensers) are installed at Balakovo NPP (Units № 1÷4) and Rostov NPP (Units 1, 2).
No thermal tests were performed at either of the Units.

8. Vacuum effect on power generation
Positive effect
Negative effect
increase in available heat drop
steam output reduction due to condensate cooling;
increase in losses with outlet velocity;
oi reduction of last stages;
increase in steam extraction to LPH

9. Efficient vacuum Determination of cooling water optimum flow rate
Power
Auxiliaries
Underproduction
Cooling water flow rate
Electric power consumption by circulation pumps
Nц 70÷80*Nс.н
Nц  Wох3

10. Design deficiencies of double-stage cassete-type separator-steam reheater:
Low heat exchange intensity due to longitudinal tube ribbing;
There are conditions for non-condensable gases accumulation in tubes;
There is thermo-hydraulic instability. Temperature pulsations reach 70ºС;
Low reliability due to thermo-hydraulic instability;
In case of tube loss of tightness, one cassette is plugged;
Low maintainability, in particular, for low tier of heat-exchange cassettes;
Complex MSR pipe connections;
Large dimensions: MSR and и heated steam pipelines are located above the turbine servicing level.
Untransportable by railway.
MSR assembly during installation.
High metal intensity and high cost.

11. Collector-platen type
Comparison of double-stage cassette-type and collector-platen type MSR (NPP-2006)
Cassette-type
1. MSR mass per Unit: 208х4=832t;
2. Metal overexpenditure per Unit: 384t;
3. MSR is equipped with 4 offset condensate collectors;
4. Four pipelines for heating steam, condensate and equalizing lines per each overheating stage;
5. ~1% of the surface is plugged in case of 1 tube leak;
6. Overhaul of tube bundles is required;
7. It is constructively impossible to cool heating steam condensate;
8. MSR height: 21,45m;
9. Pipelines occupy the area ~ equal to that of the turbine, turbine hall increase by 9 m is required;
10. Condensate discharge at saturation temperature reduces valve and pipeline service life.
Collector-platen type
1. MSR mass per Unit: 112х4=448t;
2.Metal saving per Unit: 384t;
3. 4 condensate collectors are excluded from MSR complete set;
4. One pipeline for heating steam, condensate and equalizing lines per each overheating stage;
5. 0,02% of the surface is plugged in case of 1 tube leak;
6. Overhaul of tube bundles is not required over the operation period;
7. Increase in turbine plant power by 0,4МW due to condensate cooling in intermediate overheating first stage;
8.MSR height: 13,51m (1.6 times smaller);
9. Pipelines and MSR are located under turbine servicing platform;
10. Increase in operational reliability of cooled condensate discharge valves and pipelines;
11. Reduction of mass – dimensions characteristics of PBD-Sh No.5 (due to cooled condensate dump to deaerator);
12. MSR cost per Unit is lower by ~ 46%.

12. Inter-receiver separator Powersep (BALCKE DURR)
Turbulence chamber
Condensate collection chamber
A = wet steam with x – 13 %
B = Water removal
C = dry steam
Flow chart of Powersep
Turbulence chamber

13. Inter-receiver separation system
From high pressure cylinder
Consists of a film separator and two elbow separators sequentially installed according to steam stream in turbine plant receivers,
separated water flow rate: 102 m3/h
separation efficiency: 83%
dries moist steam up to 2 %
Increases overheating by 8-10 К
To SRS
Film-type separator
Separate
Bow-type separator
Special blades
The steam inter-receiver separation system developed by JSC «VNIIAM» has been in operation at Kola NPP since the early 1990-ies and is designed for preliminary drying of moist steam coming from high pressure cylinder to moisture separator-reheater (MSR)

14. Receiver of Kola NPP turbine К-220 with blades

15. Thank you for your attention
Our coordinates:
Moscow, Cosmonaut Volkov street, 6А
Phone: 8 (499) ; 8 (499)
Fax: 8 (499)
JSC «All-Russian Research and Design-Engineering Institute of nuclear power machine building» (JSC «VNIIAM»)