Atomerőművi reaktor töltettervezése, fűtőelem

átrakás, reaktorfizikai korlátok, indítási mérések

Nemes Imre, Beliczai BotondPA 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

1

319.03

2

213.55

3

321.18

4

213.52

5

212.81

6

211.75

7

326.71

8

10.000

9

10.000

10

323.45

11

212.84

12

323.81

13

213.99

14

324.90

15

210.70

16

324.61

17

323.22

18

10.000

19

436.51

20

214.00

21

323.37

22

210.73

23

317.76

24

322.89

25

10.000

26

10.000

27

435.43

28

214.07

29

323.44

30

213.55

31

211.77

32

325.60

33

10.000

34

10.000

35

214.07

36

323.11

37

28.462

38

10.000

39

433.65

40

10.000

41

435.61

42

28.502

43

321.27

44

325.91

45

433.42

46

434.62

47

435.35

48

323.45

49

10.000

50

10.000

51

10.000

52

434.67

53

324.95

54

10.000

55

10.000

56

435.67

57

10.000

58

435.04

59

436.99

Time= 0.00 eff.day

Power= 1375.000 MW

Tin.= 266.500 C

Mod.Flow= 30450.0 t/h

Cb= 6.655 g/kg

Reactivity= 0.0001 %

h6 pos.= 200.000 cm

2 -Ass.pos.

3 -AssAge 23.8 -AssBu[MWd/kgU]

AssAge:

3.84: 4.04

3.63: 3.84

3.43: 3.63

3.23: 3.43

3.02: 3.23

2.82: 3.02

2.62: 2.82

2.41: 2.62

2.21: 2.41

2.01: 2.21

1.80: 2.01

1.60: 1.80

1.40: 1.60

1.19: 1.40

0.99: 1.19

Results of C-PORCA Calculations

Unit=3 Cycle=16

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

Tsub-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

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/1Local power and temperature limits

Burnup limits

Parameter Limitation Reactor state

Maximal linear heat rate () < 325 W/cm(burnupdependent)

all

Maximal subchanel outlet temperature Tsat all

Parameter Limitation

Assembly burnup < 49 GWd/tUPin burnup < 55 GWd/tUPin local (pellet) burnup < 64 GWd/tU

SABL tables/2Limits of control rod worth

Limits on reactivity conditions

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 ) > 1300 pcm< 2500 pcm

all

Efficiency of one ejected rod < 210 pcm< 730 pcm

FPHZP

Differential rod efficiency < 0.037 $/cm near critical

Parameter Limitation Reactor state

Critical boric acid concentration < 10.5 g/kg all (HZP)Shutdown margin (1) <-2000 pcm HZP ( 260 C)Shutdown margin (2) < 0 ZP, 210 CMinimal subcriticality during refuelling condition (themost effective follower in the core)

< -5000 pcm Zero power , 100 C

SABL tables/3

Reactivity feedback coefficient limits

Parameter Limitation Reactor state

Boric acid efficiency < -1900 pcmkg/g> -1000 pcmkg/g

allall

Moderator temperature efficiency < 0.0 pcm/K> -70.0 pcm/K all

Doppler efficiency < -2.4 pcm/K> -4.9 pcm/K

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 uncertaintiesParameter Uncertainty

Maximal linear heat rate 39 W/cmMaximal subchanel outlet temperature 7.5 C

Assembly burnup 7.65 %Pin burnup 13.6 %Pin local (pellet) burnup 13.6 %

Efficiency of all control rods, except the most effective one 10 %Integral efficiency of group 6 rods (regulating group ) 10 %Efficiency of one ejected rod 10 %Differential rod efficiency 0.00462 $/cm

Critical boric acid concentration 4.5 %Shutdown margin (1) 750 pcmShutdown margin (2) 750 pcmMinimal subcriticality during refuelling condition (the most effectivefollower in the core)

750 pcm

Boric acid efficiency 100 pcm/kg*gModerator temperature efficiency 2.5 pcm/CDoppler efficiency 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 f or the testing ofcalculated parameter uncertaintyShort term : immediate decision to declare the“goodness” of refuelled core

checking of parameter value diff erence between measured and calculated

value

Both case purpose : check the most importantparameters summarised in SABL table

Test Short description

Criticality test Criticality at 210-220 CMeasur. of critical cb af terstabilisation

Test of control roddriver connection

Reactivity changes during themovement of each CR

/ t measurement Heating of primary circuit 210-260 CMeasurement of reactivitythrough quasistatic states

Effi ciency of centralrod

Measurement of reactivitythrough quasistatic states

Measurement ofeff ectivityof all rods except themosteff ective one

Rod drop measurement( dynamic)

Thermocouplecalibration

I n a stable state withhomogeneous temperatures

/ h6, / cb

measurement

Dilution of primary circuitMeasurement of reactivitythrough quasistatic states

SymmetrymeasurementCheck of powerdistribution

on power

Start-up testprogramof NPP Paks

Types of acceptance criteria

Absolute :

prescription f or the measured value provide the parameter value within the limit

Relative :

prescription f or the bias f rom calculated provide the accuracy of calculation within a

range through the calculation and bias provide the

parameter values within the limit

Measuredparameters

AcceptancecriteriaAbsolute Relative

Critical boron atHZP

yes yes

/ tm yes yesEff ectivity of allrods except themost eff ective one

no yes

effi ciency ofcentral rod

no yes

/ h6, (h6) no yes

Measured parameters and acceptance criterias at NPP Paks practice

INPUT surface

(BEA )

General INPUT

Burnup state files

C-PORCA 6.0

OUTPUT surface

( C-COW )

General Output

HELIOS

CERBER

( BOSSY version )

VERONA Cycle data

Refuelling documentation FGCS library

FGCS library

COBRA COBRA

Töltettervezés módszerei és eszközei Pakson

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&Vmathematical 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