Experience of new fuel assembly
operation and perspectives of fuel cycle
development for for NPP with VVER
Author:
Мokhov V. А.
International scientific and technical conference
“Nuclear engineering safety, efficiency and economy”
Moscow, May 26-27, 2010
New fuel assemblies – TVS (2М)
Short background of the new fuel development for VEER-1000
The new Russian fuel is an aggregate of design and technological
upgradings performed beginning with the end of the 90-ies and
appearing in the form of TVS-2 (2M) and TVSA fuel assemblies
(FA), on the basis of which universal fuel cycles were developed
but whose designs are essentially different.
This presentation concerns TVS-2 (2М) which became a prototype
for the new design of AES-2006 fuel assemblies.
This fuel was developed not simultaneously with the reactor unit
design but independently, with the adaptation to the conditions of
power units already under operation, with the aim of reducing the
fuel constituent of the operational costs and reserving the VVER
fuel market for the Russian Supplier
2
New fuel assemblies – TVS-2 (2М)
Relevant operational objectives
•NPP unit power increase
•Introduction of 18-month fuel cycles
•Operational properties improvement
Capacity factor
increase
•Reduction of natural uranium specific
consumption
Fuel assembly design features
•Fuel loading increase
•Increase of the fuel initial enrichment to 5%
•Modernisations and justifications for reliability growth
during handling and operation
3
New fuel assemblies – TVS-2 (2М)
Main design solutions for canless TVS-2 (2М)
of VVER-1000 reactor
• skeleton made by way of the welding of spacers and guide
channels;
• guide channel size 13х1 mm;
• central spacer with the height of 30 mm, with a cell wall
thickness of 0.3 mm, distributed in the bundle with the pitch of
340 mm;
Сопряжение
ячейки с
твэлом
• fuel elements with Dlower=9.1 mm with various versions of the
fuel column structure;
0,3
• removable head;
• tail-piece containing ADF (anti-debris filter);
• film-type spacer of honeycomb type;
• core height - 3680 mm.
Participants of TVS -2 (2М) development:
OJSC ‘TVEL”, ОКБ “HYDROPRESS”, ОАО “VNIINM”, RSC
“Kurchatov Institute”, OJSC «NZHKN”,SSC RF FEI
4
5
6
46
446
New fuel assemblies – TVS-2 (2М)
Design continuity, with significant
improvement of shape stability.
2.
Compatibility with previous construction
proved by operation experience.
3.
Sufficient invulnerability during
transportation and technical operations
(ТТО).
4.
Optimized pitch of spacers providing for
the FA stiffness and fuel element fretting
wear absence
255
1.
258
250
30
3805
13255=3315
210
TVS-2 (2M) significant features
УТВС, ТВС- 2 с 15 ДР
ТВС- 2 с 12 ДР
ТВС- 2М
7
TVS-2 (2M) operation experience
Number of FAs under operation
For Volgodonsk NPP
power units
For Balakovo NPP power units
Year
Total
1
2
3
4
1
2
2003
54
54
-
-
-
-
-
2004
162
54
54
54
-
-
-
2005
217
55
54
54
54
-
-
2006
164
48 (6)
55
-
55
-
-
2007
271
54
48
55
60
54
-
2008
222
- (60)
60
54
-
48
-
2009
427
-
72
72
72
48
- (163)
Total as of April 2010
1517
331
343
289
241
150
163
Maximum burnup rate
achieved, MW*day/kg U
50.67
50.36
46.90
49.67
50.67
31.20
-
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TVS-2 (2M) operation experience
General indicators
•Time of CPS control element drop – less than 2.5 s.
•CPS control element movement effort – less than 6 kgf
Characteristic
•Efforts for FA withdrawal from – installation in the core –
within the design limits (±75 kgf)
of “fresh” core
•Reliability achieved – 1.6·10-6
•Capacity factor achieved – 90% (with accompanying
reliable equipment operation)
•Currently, there are no leaky fuel elements at power
units with TVS-2 (2М)
•Integral indicator of TVS-2 (2M) deformation absence –
logical summary growth of fuel assemblies for ~ 1.5 mm
per cycle
9
TVS-2 (2M) operation experience
Increase of core reloading speed with TVS-2 (2М)
Извлечение
Установка
4500
4500
4000
4000
3500
3500
3000
3000
2500
2500
Accompanying factor:
Force of tearing off the rims
from cell field, acc. to NZHK
data, is ~ twice as large as
maximum possible effort applied
to FA during reloading – 225 kgf
Высота, мм
Высота, мм
1,2 м/мин
1,8 м/мин
2,4 м/мин
3,0 м/мин
2000
2000
4,0 м/мин
1500
1500
1000
1000
500
500
0
0
0
20
40
60
Изменение веса, кгс
80
100
Уставка
75 кгс
At Balakovo NPP, the speed
of TVS-3 92M) vertical
movement in the core was
set as 1.2 m/min.
0
20
40
60
80
100
Justified in the design:
maximum – 4.0 m/min.
Изменение веса, кгс
10
TVS-2 (2M) operation experience
Diagram of primary coolant activity at Balakovo NPP Unit 2
during the transition to 104 % Nном
Campaign 16, operation at 100 % Nном,
tests at 104 % Nном
3200
Campaign 17,
operation at 104 % Nном
3200
1,0E-03
1,00E-03
3000
3000
100% Nном
100% N ном
2800
2800
Мощность
2600
2600
Мощность
1,00E-04
2000
1800
2400
Активность, Ки/кг
2200
Тепловая мощность, МВт
2400
Активность, Ки/кг
Тепловая мощность, МВт
1,0E-04
2200
2000
1800
1,00E-05
1,0E-05
Активность
1600
1600
Активность
1400
1400
1200
1200
1000
31.10.07
1,0E-06
18.12.07
11.02.08
28.03.08
Дата
12.05.08
26.06.08
1000
02.09.2008
13.10.2008
27.11.2008
16.01.2009
04.03.2009
Дата
20.04.2009
08.06.2009
22.07.2009
1,00E-06
03.09.2009
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Fuel cycle development
Power increase and transition to 3х18 month fuel cycle
(taking Balakovo NPP Units 1&2 as an example)
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Fuel cycle development
Perspective fuel cycle 5х1 year
Parameter
Peaking factor of fuel element relative power in the core (maximum), Кr
Value
1.63
Engineering coefficient for heat flow, Kqeng:
- For the first peripheral row of fuel elements;
- For the remaining fuel elements
1.65
1.15
1.12
1.10
Reactor thermal power, MW
3120
Coolant flow rate through the reactor (at the reactor inlet temperature), m3/h
83870
Averaged coolant flow rate through FAs, referenced to the reactor inlet temperature, m3/h (minus
coolant leaks, 3 %)
469.3
Coolant temperature at the reactor inlet, С
Minimal burnout ratio, Кmar
290
1.35
1.32
The worst modes, by the justification results of power increase to 104 % Nном, were considered:
- NPP blackout;
- loss of feedwater delivery to all steam generators;
- large LOCAs as a result of pipeline rupture (RD>100 mm, including main circulation pipeline rupture)
Taking into consideration modernizations introduced during the power increase to 104% Pnom:
Burnout in the modes “NPP blackout” and “loss of feedwater delivery to all steam generators” does not occur
As a result of variant calculations of “Large LOCAs…” mode maximum design basis limit of fuel element damage occurs:
- max. fuel temperature does no exceed the fuel melting temperature
- local depth of fuel element cladding oxidation – no more than 18 % of the initial wall thickness
- max. temperature of fuel element cladding does not exceed 1200 С
- share of oxidized zirconium does not exceed 1.0 %
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Fuel cycle development
Fuel cycle duration at uranium consumption increase for
various power levels
14
In-core inspection system upgrading at the introduction
of TVS-2M with elongated fuel column
In-core measuring channel
(КNI), located in FA
Location of KNI-5B self-powered sensors relative to the fuel
and and spacers of TVS-2М for V-320
Optimal variant of self-powered sensors location in
modernized KNI along the TVS-2M core height
It is planned to join thermal control and core power
density control with the aid of KNIT, similar to modern
designs (foreign, AES-2006)
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Relevant objectives of design and fuel cycle further
development
1. Introduction in pilot operation of FAs with increased uranium
consumption
2. Introduction of new alloys (E110М, E125, E635М)
3. Introduction of fuel assemblies with simplified withdrawal of
fuel elements
4. Introduction of mixing spacers
5. Axial profiling of fuel and burnable absorber
6. Implementation of fuel cycles with fuel burnup of more than 60
MW*day/kg U
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Conclusion
Basic design of TVS-2 (2М) has a problem-free
operational experience and is a reliable basis for
further upgradings
Thank you!
17