Transcript 19th fuel loading, Kola NPP unit 3

17th Symposium of AER
on VVER Reactor Physics and Reactor Safety
September 24-29, 2007, Yalta, Crimea, Ukraine
FUEL PERFORMANCE AND
OPERATION EXPERIENCE OF
VVER-440 FUEL IN IMPROVED
FUEL CYCLE
A. Gagarinski, V. Proselkov, Yu. Semchenkov
Russian Research Center “Kurchatov Institute”
Moscow, Russia
1
Since September 2002, Kola NPP performs works
introducing second-generation fuel in VVER-440 reactors.
Currently this second-generation fuel is in trial operation at
unit 3 (fuel cycles No 18-21, 2002-2007) and unit 4 (fuel cycles
No 18-19, 2005-2007).
The first 2nd-generation fuel for VVER-440 was loaded
in Kola-3 reactor during its 18th fuel loadinge (September 2002July 2003)
2
The fresh fuel of this 18th fuel loading included the following new secondgeneration assemblies:
54 fuel assemblies with average U-235 enrichment of 4.25%, and with
Gd2O3 burnable absorber (6 gadolinium fuel elements) integrated into the
fuel;
235.
6 CR fuel followers with average fuel part enrichment of 3.82% of U-
The fresh fuel of the next, 19th fuel loading (performed during the scheduled
preventive maintenance (SPM) in 2003) also consisted of second-generation
assemblies only:
54 fuel assemblies with average U-235 enrichment of 4.25%, and with
Gd2O3 burnable absorber (6 gadolinium fuel elements) integrated into the
fuel;
235.
12 CR fuel followers with average fuel part enrichment of 3.82% of U-
The 20th fuel loading (SPM-2004) consisted of 60 working assemblies and 6
second-generation assemblies.
The 21st fuel loading (SPM-2006) consisted of 54 working assemblies and3 12
second-generation assemblies.
Since April 2005, an improved fuel cycle similar to
that of unit 3 using the 2nd-generation fuel for
VVER-440 reactors is being introduced at unit 4
Kola NNP.
4
VVER-440 fuel assembly parameters

increased pitch between fuel elements in fuel clusters (from 12.2
to 12.3 mm for fuel assemblies and for CR fuel followers);
increased fuel column length in fuel rods (from 2424 to 2480 mm
for FA);
reduced central hole diameter in fuel pellets (from 1.6 to 1.35 mm);
increased external diameter of fuel pellets (from 7.57 to 7.60 mm);
reduced external diameter of fuel elements (from 9.1 to 9.07 mm);
Gd2O3 burnable absorber (3.35%) integrated into the fuel;
use of hafnium plates in CR fuel followers coupler part;
turnkey housing size for FA and CR-FF types (145 mm);
fuel element coating made of zirconium-niobium (1%) alloy with
reduced hafnium content (to 0.01%);
stronger fixation of fuel elements into assemblies .
5
Power density limits for second-generation assemblies
with 4.25% enrichment
qlMAX= 325 W/cm
Ëèí åéí àÿ òåï ë î âàÿ ì î ù í î ñòü, Âò/ñì
Linear Heat Rate, Wt/cm
qladd in accordance with the admissible local linear heat
rate curve depending on the burnup fuel rod.
350
(0,325)
(15,325)
300
(35,285)
250
(60,215)
200
(70,200)
150
100
50
0
0
10
20
30
40
50
Ñðåä í åå âû ãî ðàí èå â òâýë å, Ì Âò ñóò/êãU
Average Burnup in Fuel Rod, MWd/kgU
60
70
6
Trial operation data for second-generation fuel
assemblies
After two fuel loading maximum average assembly burnup
was achieved in second-generation assemblies
of unit 4 (by the end`19th fuel loading):
24.13 MWday/kgU
for fuel assemblies.
After three fuel loading maximum average assembly burnup
was achieved in second-generation assemblies
of unit 3 (by the end of its 20th fuel loading):
35.7 MWday/kgU
for fuel assemblies
7
35
25
20
15
10
35-36
34-35
33-34
32-33
31-32
30-31
29-30
28-29
27-28
26-27
25-26
24-25
23-24
22-23
21-22
20-21
19-20
18-19
17-18
16-17
15-16
14-15
13-14
12-13
0
11-12
5
10-11
Количество
ТВС
of assemblies
Number
30
Burnup ranges, MWday/kg
Интервалы выгораний, МВт*сут/кг
Burnup distribution in second-generation working assemblies
based on the results of 3 years of 2nd-generation assemblies’
8
operation at unit 3
Calculated and experimental concentrations
of the liquid absorber (boric acid) are
compared during fuel operation cycles It can
be seen that the calculated values of critical
boric acid concentrations correspond to the
results of measurements.
9
Critical boric acid concentration changing in the process of
burnup fuel loading,
18th fuel loading of Kola NPP unit 3
CH3BO3, g/kg H2O
measurements
calculations
10
Critical boric acid concentration changing in the process of
burnup fuel loading,
19th fuel loading of Kola NPP unit 3
CH3BO3, g/kg H2O
measurements
calculations
11
Critical boric acid concentration changing in the process of
burnup fuel loading,
20th fuel loading of Kola NPP unit 3
12
Critical boric acid concentration changing in the process of
burnup fuel loading,
19th fuel loading of Kola NPP unit 4 (2007 year)
13
20th fuel loading of Kola NPP unit 3
Specific conditions of Kola NPP operation in an isolated energy system
resulting in an insufficient demand for its electricity compels one of its units
to operate at only 50% of its design capacity
14
19th fuel loading of Kola NPP unit 4 (2007 year)
15
Deviation statistics
Experiment-Calculation)
/Calculation,
in % for assemblies having
different operation periods
red
- 1 cycle;
yellow - 2 cycles;
green
- 3 cycles;
turquoise- 4 cycles;
blue
- 5 cycles;
violet
- 6 cycles.
(
Measuring date:18.03.2005
Effective days: 150.6
Power: 1354 MW.
The results of comparison of Kq (relative assembly power) measured by
thermocouples and calculated for selected moments of unit 3, 20th fuel loading.
16
Deviation statistics
Experiment-Calculation)
/Calculation,
in % for assemblies having
different operation periods
red
- 1 cycle;
yellow - 2 cycles;
green
- 3 cycles;
turquoise- 4 cycles;
blue
- 5 cycles;
violet
- 6 cycles.
(
Measuring
date:04.10.2006
Effective days: 107.8
Power: 1354 MW.
The results of comparison of Kq (relative assembly power) measured by
thermocouples and calculated for selected moments of unit 4, 19th fuel loading.
17
Primary circuit water chemistry data
The primary circuit of Kola-3 operated in a
reducing, faintly alkaline, ammonium-potassium
water chemistry mode using boric acid, in accordance
with existing requirements. In order to meet the water
chemistry standards by ammonium and hydrogen,
hydrazine hydrate was supplied to the intake header
of makeup pumps. In steady-state operation
conditions, the contents of alkaline metals, chlorides
and corrosion products, pH, and hydrogen
concentration in the primary coolant were within the
standard limits throughout the reported year.
18
Primary coolant activity and special water treatment-1
coolant flow data
Specific activity of the primary coolant determined for the
sum of iodines during the operation of the 18th and 19th load
patterns of unit 3 stayed at a low level of 310-5 Ci/kg. The
growth of coolant activity up to 310-5 Ci/kg at the initial stage
(15.09.02-24.12.02) of the 18th fuel loading operation at unit 3
was caused by its power increase to 100%. In course of further
operation, the coolant activity stayed practically unchanged.
The absence of coolant activity excursion in the moment of
actuation of emergency protection system-1 (18th fuel load
pattern) shows that no fuel elements having significant
cladding defects are present in the core.
19
NGFP total
Сум.йод
6,00E-05
5,00E-05
Activity, Ci/kg
4,00E-05
3,00E-05
2,00E-05
1,00E-05
0,00E+00
Specific activity of iodines and non-gaseous fission products in the primary coolant;
Date
18th fuel load pattern, Kola NPP unit 3
G, t/h
Nt,%
120
100
80
60
40
20
0
Thermal power (%) and SWT-1 coolant flow rate (t/h);
18th fuel load pattern, Kola NPP unit 3
Date
20
Thermal power (%) and SWT-1 coolant flow rate (t/h);
19th fuel loadind, Kola NPP unit 3
21
18.06.2004
11.06.2004
04.06.2004
28.05.2004
21.05.2004
14.05.2004
07.05.2004
30.04.2004
Nt %
23.04.2004
16.04.2004
18.06.2004
11.06.2004
04.06.2004
28.05.2004
21.05.2004
14.05.2004
07.05.2004
30.04.2004
23.04.2004
16.04.2004
09.04.2004
02.04.2004
26.03.2004
19.03.2004
12.03.2004
05.03.2004
27.02.2004
20.02.2004
13.02.2004
06.02.2004
30.01.2004
23.01.2004
16.01.2004
09.01.2004
02.01.2004
26.12.2003
19.12.2003
12.12.2003
05.12.2003
28.11.2003
21.11.2003
14.11.2003
07.11.2003
31.10.2003
24.10.2003
17.10.2003
10.10.2003
03.10.2003
26.09.2003
19.09.2003
12.09.2003
1, E-03
09.04.2004
02.04.2004
26.03.2004
19.03.2004
12.03.2004
05.03.2004
27.02.2004
20.02.2004
13.02.2004
06.02.2004
30.01.2004
23.01.2004
16.01.2004
09.01.2004
02.01.2004
26.12.2003
19.12.2003
12.12.2003
05.12.2003
28.11.2003
21.11.2003
14.11.2003
07.11.2003
31.10.2003
24.10.2003
17.10.2003
10.10.2003
03.10.2003
26.09.2003
19.09.2003
12.09.2003
I total
NGFP total
1, E-04
1, E-05
1, E-06
Specific activity of iodines and non-gaseous fission products in the primary coolant;
19th fuel loading, Kola NPP unit 3 (2 hours after sampling), Ci/kg
120
Q SWT-1 (t/h)
100
80
60
40
20
0
Conclusion
The specific geographical position of Kola NPP and the state
of the surrounding region’s economy determine the strategy of
power units’ operation in the area of fuel use.
 Isolated energy system and, as a consequence, excessive
generating capacities compel Kola NPP to operate at low
power, though its units’ operation at their maximum power
may be needed in some unplanned situations.
In the same time, the results of trial industrial operation of
second-generation fuel at Kola NPP units 3 and 4 demonstrate
a high reliability of new fuel types, which is confirmed by low
primary coolant activity levels and by the cladding leakage
monitoring data.
22
The process of trial industrial operation of second-generation
assemblies includes the comparison of calculated and
experimental data performed in order to check the compliance
of fuel’s neutronic parameters with the theoretical physical
project of fuel cycle implementation, as well as to update the
related software and the database of constants.
Starting from the third refueling, the divergences of fuel load
operating cycle and of the liquid absorber concentration in
power operation mode were discovered, which required the
works on identifying the reasons of these divergences and on
correcting the constants to be organized. Regulatory documents
provide for the updating of neutronic constants on the basis of
operating data.
Technical solutions laid in the design of second-generation
fuel assemblies, were proven and confirmed by the results of
23
trial and commercial operation.