1. Prof. dr. ir. ing. René Boonen
The formation of hydrogen flakes during fabrication of the reactor pressure vessel.
dr. ir. Jan Peirs
Prof. dr. ir. ing. René Boonen
13/04/2018
INRAG Fachtagung

2. Overview Location and distribution of flakes Hypothesis of Electrabel
Overview
Location and distribution of flakes
Hypothesis of Electrabel
Test hypothesis: calculate hydrogen balance

3. Reactor vessel construction3
Reactor vessel construction

4. 4
Distribution of flakes around the circumference of the Doel3 lower shell
7200 flakes
25.8 / L
11600 flakes
41.6 / L

5. Size distribution of the flakes5
Size distribution of the flakes

6. Hypothesis of Electrabel
Hypothesis of Electrabel
Cracks formed during production
During transformation from gamma to alfa phase, the segregation zones become supersaturated in hydrogen which will recombine to hydrogen gas H2 at trapping sites in the metal, building up an internal pressure.
Pressure -> cracks
Cracks already present at start-up of the reactor
Reactor vessel is stable, flakes do not grow => safe

7. Test Electrabel hypothesis: hydrogen balance7
Test Electrabel hypothesis: hydrogen balance
Amount of hydrogen available during production ?
Amount of hydrogen required to create present measured amount of cracks ?
if(available hydrogen < required for cracks) then hypothesis = false

8. Available hydrogen measured (in liquid state)8
Available hydrogen measured (in liquid state)

9. Crack formation: calculation
Crack formation: calculation p
Calculation based on equilibrium at final state of flake
KIC & a ->  -> FEM -> volume of flake under pressure -> volume of H2
p = 
KIc : critical stress intensity factor (material parameter)
: bulk stress or internal pressure in flake
a: radius of flake

10. Determination of the critical stress intensity factor10
Determination of the critical stress intensity factor
Use KIC of the lower shelf of the ASME curve
40 MPa/m
Minimum amount of required H2
In reality: even more H2 required (conservative approach)

11. Volume of flake under internal H2 pressure11
FEM analysis
Volume of flake under internal H2 pressure

12. Crack formation: volume
Crack formation: volume
Crack grows Equilibrium, crack stops growing H2 has disappeared, crack closes again }
dV x p

13. Total H2 volume for 11600 flakes13
Total H2 volume for flakes

14. Hydrogen balance Full shell ( 4 m, H=2,5 m, d=0,2 m)14
Hydrogen balance
Full shell ( 4 m, H=2,5 m, d=0,2 m)
Available: 383 L H2
Required: 375 L H2
No H2 should escape through the walls
High density zone with 41 flakes / L
Available: 61 mL / L
Required: 1373 mL / L
Factor 22 short

15. Conclusion
Our calculations show that there is not sufficient hydrogen available during production to form all the flakes.
Only limited number of flakes can be explained by this mechanism
Hypothesis of Electrabel does not explain flakes.

16. Apparently, Electrabel has not investigated the volumetric hydrogen balance.
Electrabel should recalculate the hydrogen balance using their extensive dataset which they have at their disposal.

17. Einladung Part 2 of this study: Prof. dr.-ing. René Boonen
Einladung
Part 2 of this study:
Prof. dr.-ing. René Boonen
Saturday 10:45
“Ungelöste Probleme der Materialstruktur des Reaktordruckbehälters von Tihange 2“
Extended calculation for different KIC at room temperature
Upper and lower shells

19. Breukmechanica - Scheuren hebben energie nodig om te groeien.19
Breukmechanica
- Scheuren hebben energie nodig om te groeien.
- 4 soorten energie:
- elastische energie (leverancier)
- plastische energie
- oppervlakte-energie (scheurgroei)
- kinetische energie (materiaalverplaatsing, kraakgeluid)
-Scheuren groeien onder cyclische belasting.

20. 20
Breukmechanica
Scheurvormen
Stress Intensity Factor SIF:

21. Breukmechanica RT Curve bepaald door trekproeven en kerfslagproeven

22. 22
Breukmechanica

23. Oplosbaarheid waterstof in staal