Atomerőművi reaktor
töltettervezése, fűtőelem
átrakás, reaktorfizikai
korlátok, indítási mérések
Nemes Imre, Beliczai Botond
PA Zrt
Tartalom
• Üzemanyag cseréről általában
• Reaktorfizikai korlátok
• Reaktorfizikai mérések és
értékelésük
• Töltettervezés módszerei és eszközei
Pakson
Üzemanyag csere általában
• Ciklikus működésű reaktorok : PWR,BWR
• 1 ciklus (kampány) hosszát meghatározzák
– technológia feltételek, gazdaságossági
megfontolások
– reaktivitás tartalék
• Reaktivitás tartalék :
– friss üzemanyag értékessége : dúsítás, uránsúly,
geometria
– átlagos kiégés
Dúsítás-kiégés-kampányhossz
Tipikus
VVER-440
töltet
Results of C-PORCA Calculations
AssAge:
Unit=3 Cycle=16
3.84: 4.04
3.63: 3.84
3.43: 3.63
59
4
36.99
3.23: 3.43
3.02: 3.23
2.82: 3.02
57
1
0.000
T ime= 0.00 eff.day
Power= 1375.000 MW
T in.= 266.500 C
Mod.Flow= 30450.0 t/h
Cb= 6.655 g/kg
Reactivity= 0.0001 %
h6 pos.= 200.000 cm
2
3
23.8
48
3
23.45
42
2
8.502
35
2
14.07
28
2
14.07
20
2
14.00
1
3
19.03
2
2
13.55
49
1
0.000
36
3
23.11
21
3
23.37
2.41: 2.62
44
3
25.91
30
2
13.55
13
2
13.99
45
4
33.42
31
2
11.77
14
3
24.90
code info:/3/16/val/kov/0/-/parameters:
value:
sec:
ass.pos:
pinpos:
layer:
Ass.Pow-max[MW]:
5.310
1
49
Ass.Bu-max[MWd/kgU]:
36.99
1
59
PinPow-max[kW]:
45.58
1
50
1
PinBu-max[MWd/kgU]:
41.86
1
59
120
T sub-max[C]:
315.6
1
38
83
Nlin-max[W/cm]:
247.8
1
50
1
9
Nlin-limit[W/cm]:
325.0
1
50
1
9
LocPinBu-max[MWd/kgU]:
48.52
1
59
120
8
1.19: 1.40
0.99: 1.19
41
4
35.61
34
1
0.000
26
1
0.000
17
3
23.22
8
1
0.000
1.40: 1.60
47
4
35.35
33
1
0.000
16
3
24.61
1.60: 1.80
40
1
0.000
25
1
0.000
7
3
26.71
1.80: 2.01
46
4
34.62
32
3
25.60
15
2
10.70
2.01: 2.21
52
4
34.67
39
4
33.65
24
3
22.89
6
2
11.75
56
4
35.67
51
1
0.000
38
1
0.000
23
3
17.76
5
2
12.81
55
1
0.000
50
1
0.000
37
2
8.462
22
2
10.73
4
2
13.52
54
1
0.000
43
3
21.27
29
3
23.44
12
3
23.81
3
3
21.18
2.62: 2.82
2.21: 2.41
53
3
24.95
-Ass.pos.
-AssAge
-AssBu[MWd/kgU]
11
2
12.84
58
4
35.04
27
4
35.43
18
1
0.000
9
1
0.000
19
4
36.51
10
3
23.45
Reaktorfizikai korlátok
• Neutron és hőfizikai paraméterek listája,
amelyek a reaktor stacioner állapotát
jellemzik
• Korlátként, keretként szolgálnak,
betartásuk szükséges a reaktor
biztonságos állapotához
• Tervezéskor olyan töltetet rakunk össze,
hogy ezek a limitek teljesüljenek
The way of determination during SA
• Equilibrium cycle features used as a basis
• Key parameters of a given analysis were chosen
• Parameters adjusted to provide conservative
results
• Conservatism include :
– Uncertainty of parameter
– Deviations in transient cycles
•
Conservatism limited by
– acceptance criteria
– physical feature of model
SABL tables/1
Local power and temperature limits
Parameter
Limitation
Maximal linear heat rate ()
< 325 W/cm all
(burnup
dependent)
Tsat
all
Maximal subchanel outlet temperature
Burnup limits
Parameter
Limitation
Assembly burnup
Pin burnup
Pin local (pellet) burnup
< 49 GWd/tU
< 55 GWd/tU
< 64 GWd/tU
Reactor state
SABL tables/2
Limits of control rod worth
Parameter
Limitation
Reactor state
Efficiency of all control rods, except the most effective one > 5100 pcm
all
Integral efficiency of group 6 rods (regulating group )
all
Efficiency of one ejected rod
Differential rod efficiency
> 1300 pcm
< 2500 pcm
< 210 pcm
< 730 pcm
< 0.037 $/cm
FP
HZP
near critical
Limits on reactivity conditions
Parameter
Limitation
Reactor state
Critical boric acid concentration
Shutdown margin (1)
Shutdown margin (2)
Minimal subcriticality during refuelling condition (the
most effective follower in the core)
< 10.5 g/kg
<-2000 pcm
<0
< -5000 pcm
all (HZP)
HZP ( 260 C)
ZP, 210 C
Zero power , 100 C
SABL tables/3
Reactivity feedback coefficient limits
Parameter
Limitation
Reactor state
Boric acid efficiency
< -1900 pcmkg/g
> -1000 pcmkg/g
< 0.0 pcm/K
> -70.0 pcm/K
< -2.4 pcm/K
> -4.9 pcm/K
all
all
Moderator temperature efficiency
Doppler efficiency
all
all
Uncertainty determination
• linear power, subchanel temperature
burnup limits : a detailed analysis taking into
account material tolerances and calculation errors
• boron
concentration,
boron
worth,
moderator
temperature
coefficient,
control rod worth : deviations between the
measured and calculated parameter values.
• Rest of parameters : benchmark calculations
Parameter uncertainties
Parameter
Uncertainty
Maximal linear heat rate
Maximal subchanel outlet temperature
39 W/cm
7.5 C
Assembly burnup
Pin burnup
Pin local (pellet) burnup
7.65 %
13.6 %
13.6 %
Efficiency of all control rods, except the most effective one
Integral efficiency of group 6 rods (regulating group )
Efficiency of one ejected rod
Differential rod efficiency
10 %
10 %
10 %
0.00462 $/cm
Critical boric acid concentration
Shutdown margin (1)
Shutdown margin (2)
Minimal subcriticality during refuelling condition (the most effective
follower in the core)
4.5 %
750 pcm
750 pcm
750 pcm
Boric acid efficiency
Moderator temperature efficiency
Doppler efficiency
100 pcm/kg*g
2.5 pcm/C
20 %
Startup test at NPP Paks
 What we measure ?
 Why we measure these ?
 How to evaluate results ?
 How we declare the acceptance of results ?
Purposes of measurements
Long term : data collection for the testing of
calculated parameter uncertainty
Short term : immediate decision to declare the
“goodness” of refuelled core
 checking of parameter value
 difference between measured and calculated
value
Both case purpose : check the most important
parameters summarised in SABL table
Start-up test
program
of NPP Paks
Test
Criticality test
Test of control rod
driver connection
/t measurement
Efficiency of central
rod
Measurement of
effectivity
of all rods except the
most
effective one
Thermocouple
calibration
/h6, /cb
measurement
Symmetry
measurement
Check of power
distribution
Short description
Criticality at 210-220 C
Measur. of critical cb after
stabilisation
Reactivity changes during the
movement of each CR
Heating of primary circuit 210260 C
Measurement of reactivity
through quasistatic states
Measurement of reactivity
through quasistatic states
Rod drop measurement
( dynamic)
In a stable state with
homogeneous temperatures
Dilution of primary circuit
Measurement of reactivity
through quasistatic states
on power
Types of acceptance criteria
Absolute :
 prescription for the measured value
 provide the parameter value within the limit
Relative :
 prescription for the bias from calculated
 provide the accuracy of calculation within a
range
 through the calculation and bias provide the
parameter values within the limit
Measured parameters and acceptance criterias
at NPP Paks practice
Measured
parameters
Critical boron at
HZP
/tm
Effectivity of all
rods except the
most effective one
efficiency of
central rod
/h6, (h6)
Acceptance
criteria
Absolute
yes
Relative
yes
yes
no
yes
yes
no
yes
no
yes
Töltettervezés módszerei és
eszközei Pakson
COBRA
COBRA
CERBER
FGCS library
HELIOS
( BOSSY version )
Burnup state
files
OUTPUT surface
INPUT surface
( C-COW )
(BEA )
General
INPUT
FGCS library
C-PORCA
6.0
General
Output
VERONA
Cycle data
Refuelling
documentation
HELIOS application for Paks
• Generate few-group cross section
libraries for C-PORCA 2.0, 5.0, nodal
and pin-wise models
• Validate few-group diffusion codes
calculating different test cases
HELIOS few-group cross section
calculations / Paks specific features
• 45 (190) -group 2D transport code
• detailed and flexible geomery
• developed handling and services
• few-group parameters for non-multiplying
regions as well - no boundary conditions
• Pin-cells with different spectral position
handled separately
Geometries for HELIOS
calculation
CERBER - for refuelling
design
• Fast and effective 3D nodal diffusion
model ( C-PORCA 2.0)
• Interactive WINDOWS surface Bossy version
• Different options of automatic
optimisation
The BOSSY WINDOWS surface
for CERBER calculations
C-PORCA 6.0
• 2-group 3D diffusion code - combined
nodal and pin-wise calculations
• 20 axial layers, 127 cells/assembly
• Modules included for data preparations
for VERONA system
• Detailed and continuous validation
• Developed services
Evaluation of C-PORCA results
using C-COW output surface
C-PORCA 5.0 V&V
 mathematical benchmarks
 HELIOS tests : nodal and pinwise
 MCNP reference calculations
 NPP Paks measured data (more then 60
cycles) : global parameters, assembly
power distribution
 Validation benchmarks : xenon, power
distributions, non-measured
parameters and cases