SPHERE irradiation

Sander van Til

Elio d’Agata (JRC-IET)

Ralph Hania

Alexander Fedorov

Raymond Okel

Dennis Boomstra

19-5-2015

Homogeneous recycle fuel tests in the world

2

• Japan: AM-1 test (finished)

• Effects at first startup: 10 minutes and 24 hours

• Linear power up to 430 W/cm

• US: AFC-1 test (PIE ongoing)

• Medium burn-up (4-8% FIMA)

• Linear power 300-400 W/cm at startup

• Metallic and nitride fuel in addition to oxides

• Europe: SPHERE test (irradiation completed)

• Medium burn-up (4-8% FIMA)

• No neptunium

• Linear power 300-330 W/cm at startup

• Comparison of pellet and sphere-pac fuel

3

SPHERE Starting Points

• A direct comparison of Am-bearing MOX fuel in Sphere-Pac andPellet form under similar conditions

• What are these same conditions?

– Same cladding temperature (500-550 oC)

– Same linear heat rate (~300 W/cm)

Due to differences in fuel smeared density, the

final burn-up will be slightly different.

• The design is based on CONFIRM:

– Double contained, sodium-filled experiment in a wet trio

– 2 connected Phenix-type pinlets

Fuel composition

4

Pin Nr. CompositionIsotopic

composition

Fuel

Density

[g cm-3]

241Am

contents

[g]

238U

content

s [g]

239Pu

contents

[g]

1

S-Pac

U0.75Pu0.22Am

0.034 O2-x

MOX

+241Am

8.33* 0.320 7.167 1.869

2

Pellets

U0.76Pu0.2Am0.

03 O2-x

MOX

+241Am

10.393

93.8 %

TD

0.388 10.192 2.442

*This overall density takes into account both the density of the sphere and the packing density

5

Cross section of the experiment

Na

150 μm gap between SS 1st and 2nd containment

Water in wet trio channel

Molybdenum shroud (TZM) containing

Thermocouples and flux detectors

15-15Ti fuel pin, Øo 6.55 mm

Mo shroud, Øi 9.2 mm, Øo 14 mm

2 SS containments + Hf shield, Øi 19.8 mm, Øo 25.5 mm

SS wet TRIO channel, Øi 31.5 mm Øo 33.5 mm

6

Axial view

7

Pin fabrication and transport (JRC-ITU)

• He-filling / welding, and subsequent leak tests and weld inspections were performed

• (He contains 1% neon).

• The sphere-pac column length is lower than intended (48 mm vs. the nominal length of 60 mm) due to losses during fabrication

Location HFR

8

Be reflector

A B C D E F G H

1 + + + +++ + + +

2 +

3 +4 +

5 + +6 +

7 +8 +

9 + + + + + + + + +

Fuel

Control rod

Irradiation

position

Initial SPHERE position

+

+

9

Results of safety calculations

• 1-dimensional thermal calculations show that for a linear power of 300 W/cm, the central temperature of both pins stays well below 2500 oC:

– Using measured thermal conductivity for the pellet fuel

– Using PINTEMP (PSI) to obtain effective conductivity of the sphere-pac column

– Not taking into account neutron self-shielding

– For unrestructured fuel

• MCNP calculations of SPHERE in HFR position G7-south yield:

– The vertical position of the experiment at which the equalpower condition is satisfied

– The required thickness of the Hf shield (~0.75 mm)

Linear power evolution

10

Linear power [W/cm]

200

220

240

260

280

300

320

0 100 200 300 400 500

Irradiation days

Po

we

r [W

/cm

]

sphere

pellets

Temperatures@BOL

11

Sample holder fabrication

12

First cycle

13

Align pins for linear power

Adjust gas mixture to reach target temperature of 450oC

Reloading U-targets in neighbouring positions

Restructuring after first cycle cycle

Central hole diameter of 1.05mm ± 0.09mm

14

Before irradiation

After 1 cycle of irradiation ( ~28FPD)

Irradiation history

cycle cycle start-up cycle shut down Pos. cycle time irrad time

T Mo,

pin 1

T Mo,

pin 2

FPD FPD C C

12013-03 28-08-13 11:10 25-09-13 8:30 G7 27.89 27.89 448 444

HFR shutdown

22014-02 18-03-14 16:40 16-04-14 7:00 G7 28.6 56.49 449 444

32014-03 25-04-14 19:00 20-05-14 16:00 G7 24.88 81.37 444 441

42014-04 1-06-14 13:50 29-06-14 16:10 G7 28.1 109.47 449 446

52014-05 4-07-14 9:30 28-07-14 16:00 G7 24.18 133.65 446 442

62014-06 1-08-14 11:20 29-08-14 16:00 G7 28.02 161.67 443 440

72014-07 2-09-14 12:30 1-10-14 8:00 G7 27.32 188.99 442 439

82014-08 5-12-14 11:20 30-12-14 14:30 G7 24.89 213.88 443 439

92015-01 3-01-15 14:00 28-01-15 16:00 F2 24.86 238.74 446 445

102015-02 19-02-15 11:20 22-03-15 16:00 F2 31.06 266.94 445 445

112015-03 26-03-15 22:30 26-04-15 16:00 F8 30.72 295.14 445 445

15

Last cycles of SPHERE

16

• Clad temperatures are stable at 520-530 oC (about 70 oC above thermocouple temperatures)

17

End of Irradiation - neutronradiograph

Schedule remainder FAIRFUELS

• Irradiation completed on 26 April 2015

• 2 month cooling time (neutron radiogram taken)

• Delivery of D 2.2.3 (will complete in coming months)

Continuation in PELGRIMM

• Dismantling and PIE from July - November 2015• Profilometry

• Gamma-scanning

• Puncture and gas analysis

• Ceramography on cross-sections for comparison to Fuel Performance Code simulations

• Cutting & preparation for transport

• Monitor set analysis and burn-up calculations

• Transport to ITU: Q1 2016, but uncertain

18

END

19

20

AM-1 test (1)

21*Maeda et a. JNM 389 (2009), 78-84

AM-1 test (2)

• Conductivity is roughly that of (U,Pu)O2-x for same x

22

• 1 day is enough for full restructuring

• No sign of fuel melting at high power

*Maeda et a. JNM 389 (2009), 78-84

AM-1 test (3)

• Fuel structure: negligible difference with MOX fuel

23*Maeda et a. JNM 389 (2009), 78-84

AM-1 test (4)

• Migration of Am and Pu less at lower O/M

• Np does not show the same tendency to migrate to center

24*Maeda et a. JNM 389 (2009), 78-84