Involvement of EDF in the Halden Reactor Project: a long-term cooperation in R&D

Transcription

1 Involvement of EDF in the Halden Reactor Project: a long-term cooperation in R&D Atoms For the Future 2016 Session: Nuclear Fuel 28/06/2016 Alexandre Lavoil alexandre.lavoil@edf.fr EDF SEPTEN/CN

2 OUTLINE 1. PRESENTATION OF THE HRP 2. COLLABORATION EDF HRP 3. FUEL ROD CONCEPTION : SOME WORDS 4. EDF INDUSTRIAL NEEDS AND CONTRIBUTION OF HRP 5. CONCLUSIONS 2

3 PRESENTATION OF THE HRP HRP: Halden Reactor Project, started in 1958 International collaborative research for the safe and reliable operation of Nuclear Power Plants Affiliated to the OECD NEA in Paris Jointly funded by the membership 20 countries including Norway >100 organizations (utilities, vendors, R&D, licensing/regulatory authorities) Budget for is 431 MNOK (~46 M ) Norway contributes 35% of HRP budget 3

4 PRESENTATION OF THE HRP HBWR : Halden Boiling Water Reactor 20 MW heavy water reactor (34 bar, 235 C) 35 simultaneous tests possible (IFA : Instrumented Fuel Assembly) Instrumentation provides data on performance of nuclear fuels and materials under normal, transient and accident conditions (dry-out & LOCA) 4

5 PRESENTATION OF THE HRP Man-Technology-Organisation Objective: provide knowledge about how and why accidents occur, with the aim of preventing them from happening in the operation of complex processing facilities Nuclear Fuels and Materials (F&M) Objective: provide knowledge about the performance of nuclear fuels and materials under normal, transient and accident conditions, with the aim of increasing safety and reliability plus improving the nuclear fuel cycle 5

6 COLLABORATION EDF - HRP HRP : Decisive and strategic topics related to fuel behaviour Major actors of the nuclear industry involved (regulators, utilities, manufacturers) Necessity for EDF to be involved in this project! Collaboration between EDF and HRP started in June st EDF representative sent in October

7 FUEL ROD CONCEPTION : SOME WORDS Fuel assembly rods - ~4.5 meters high Fuel rods mm large - ~4 meters high 7

8 Fuel thermomechanical criteria which needs to be verified Codes & Models used to demonstrate the respect of these criteria How are these codes validated? Experiences! Ø 1 mm thermocouple 8

9 Internal pressure: The pressure in the rod has to remain lower than the limit pressure which could lead to a gap re-opening One phenomena which can lead to pressure increase : Fission Gas Release (FGR) Important to understand the FGR mechanism in order to implement models in the fuel thermomechanical codes to be able to simulate it IFA-716 : Fission gas release experiment : Objectives : Onset of fission gas release Densification and swelling behaviour Inclusion of novel fuel types with improved thermal conductivity (BeO doped) (Lower fuel T => reduced fission gas release) 9

10 IFA-716 : Fission gas release experiment 6 instrumented rods with types of fuel Different grain size Different additive Different levels of Cr content UO2 large grain 10

11 Reactivity control: Gadolinium is a neutronic poison, used in some of the French PWR to control the reactivity in the beginning of life Some UO 2 Gd 2 O 3 can be inserted in the fuel assemblies, but gadolinium can modify the thermomechanical behaviour of the fuel Important to understand this behaviour in order to be able to add some specific models in the thermomechanical codes IFA : UO 2 Gd 2 O 3 fuel behaviour : objectives : Comparison between UO 2, UO 2 + 2% Gd 2 O 3, UO 2 + 8% Gd 2 O 3 Evaluation of gadolinium on: Fuel densification & swelling FGR 11

12 IFA-681.1: UO 2 Gd 2 O 3 fuel behaviour Delay of the temperature increase of the Gd fuel Similar T for the UO 2 & UO 2 +2% Lower T for the UO 2 +8% 12

13 IFA-681.1: UO 2 Gd 2 O 3 fuel behaviour No densification for UO 2 -Gd 2 O 3 Fuel swelling seems to decrease with Gadolinium content 13

14 LOCA (Loss Of Coolant Accident): Fuel rods not in contact with the coolant Important consequences on the fuel rods behaviour Heat-up phase Ballooning of the rod Fuel Fragmentation Relocation & Dispersal (FFRD) 14

15 Linear Power Cladding temperature INDUSTRIAL NEEDS / CONTRIBUTION OF HRP IFA-650 : LOCA experiment : Objectives Behaviour of a fuel rod in LOCA conditions Find the Burn-Up threshold for FFRD during a LOCA Experimental procedure: Single rod in a rig Blowdown (~100 s) SCRAM LOCA In-pile measurements: Cladding temperature Forced circulation (imposed by HBWR conditions) Natural circulation: Isolation of the loop Heat-up phase Cooldown phase Fuel rod Pressure Fuel rod elongation Activity in the loop 50 P APRP temps 15

16 IFA-650 : LOCA experiment : Post-Irradiation Examinations (PIE): 16

17 Fukushima s accident Post-Fukushima studies: Development of ATF (Accident Tolerant Fuel) 17

18 ATF (Accident Tolerant Fuel): Objectives: Pellets: High melting fuel temperature Increase thermal conductivity (to decrease centerline temperature) Enhance retention of fission products Cladding: High melting cladding temperature Maintain coolable geometry (limit ballooning & burst) Retain high post-quench ductility Reduce production of H 2 Coating of the cladding is one of the solution imaginated by the supplier 18

19 IFA-796: ATF experiment Objective: demonstrate that the in-reactor behaviour of ATF claddings is at least as good as Zr-based claddings in use today under prototypic PWR operation conditions Measurements: Oxide thickness increase Dimensional behaviour 6 rods provided by 6 manufacturers (industrials, R&D, labs ), varying: Cladding compositions Coating types and thicknesses Uncoated Zy4 Non-Optimized coating Optimized coating Experiment to be started in 2016/ IDARRAGA, LE FLEM, BRACHET et al. American Nuclear Society, Top Fuel 2013

20 CONCLUSIONS EDF HRP: a long-term cooperation in R&D HRP brings experimental answers to the industrial issues which can touch EDF Major topics of the nuclear fuel industry treated in the experiments of the HRP (LOCA, ATF ) Mains actors of the nuclear field (manufacturers, providers, regulators, research centers) of all the major countries of the nuclear world Decisive collaboration for EDF! 20

21 THANK YOU! 21