Measurements and calculations of the neutron spectrumin different irradiation channels

of the TRIGA Mark II reactor, Slovenia

R. Jaćimović1, A. Trkov2, M. Maučec3

1“Jožef Stefan” Institute, Ljubljana, Slovenia2 IAEA, Vienna, Austria3 HOLTEC International, Marlton, USA

LjubljanaSloveniaLjubljanaSlovenia

"Jozef Stefan" Institute

1st RCM of the IAEA CRP on Reference Database for NAA, Vienna, Austria

October 2005

Introduction• TRIGA Mark II reactor (250 kW) at the JSI

from 1966. • The k0-standardization method was introduced

in 1987.• TRIGA Mark II reactor (250 kW)

– irradiation channels,– neutron spectral parameters,– neutron fluence gradients,– neutron self-shielding.

• Calibrated HPGe detector– absolutely calibrated point sources,– counting geometry.

Nuclear research reactor TRIGA Mark II (250 kW)

- Short and long irradiation in the CC: th ~ 10·1012 cm-2 s-1

- Short irradiation in the PT and in the FPTS (up-to 30 min.) th ~ 3.5·1012 cm-2 s-1

- Long irradiation in the IC-40 (typically 20 hours) th ~ 1.1·1012 cm-2 s-1

Carousel

Fuel elem ents 20% U -235

Control rods

N eutron source

Irrad iation channels

Fast pneum atic transfersystem

P neum atic transpor t tubechannel

Central channel

Triangular channel

Horizontal section of the TRIGA Mark II reactor (core No. 176)

El. NuclideT1/2

(s, %)E, keV FCd Gepi

Ēr, eV,

(s, %)

Q0

(s, %)

k0

(s, %)

Au 198Au2.695 d

(0.1)411.8 0.991 1

5.65

(7.1)

15.71

(1.8) 1

Co 60Co5.271 y

(0.02)1173.2 1 1

136

(5.1)

1.993

(2.7)

1.32

(0.4)

Fe 59Fe44.63 d

(0.2)1099.3 1 1

637

(24.0)

0.975

(1.0)

7.77E-5

(0.5)

In 116mIn54.15 min

(0.1)1293.5 1 1

1.56

(1.9)

16.8

(1.9)

2.29

(0.8)

Lu 176mLu3.635 h

(0.3)88.4 1 1

16.1

(5.0)

34.8

(3.1)

1.73E-2

(1.5)

Mn 56Mn2.5785 h

(0.02)846.8 1 1

468

(11.0)

1.053

(2.6)

4.96E-1

(0.6)

99Mo66.02 h

(0.02)739.5 1 1

241

(20.0)

53.1

(6.1)

8.46E-5

(0.7)

99mTc6.02 h

(0.3)140.5 1 1

241

(20.0)

53.1

(6.1)

5.27E-4

(0.5)Mo

101Tc14.2 min

(0.7)306.8 1 1

672

(14.0)

18.84

(4.3)

3.73 10-4

(1.3)

Th 233Pa27.0 d

(0.4)312.2 1 1

54.4

(0.9)

11.53

(3.6)

2.52E-2

(0.5)

U 239Np2.335 d

(0.2)277.6 1 1

16.9

(1.2)

103.4

(1.3)

3.40E-3

(0.8)

69mZn13.76 h

(0.15)438.6 1 1

590

(10.0)

3.19

(1.4)

3.98E-4

(0.6)

Zn 65Zn244.0 d

(0.08)1115.5 1 1

2560

(10.0)

1.908

(4.9)

5.72E-3

(0.4)

Zr 95Zr64.02 d

(0.016)

724.2

+756.71 0.983

6260

(4.0)

5.306

(3.3)

2.000E-4

(1.2)

Relevant nuclear data used for determination of f and

F. De Corte, A. Simonits, Atomic Data and Nuclear Data Tables, 85 (2003) 47-67.

Spectral parameters of the neutron fluence rate: f and

CoreNo.

Irr.channel

MonitorsCd-ratio method

f

PT13.6.2000

198Au-69mZn-65Zn-95Zr

31.780.71 -0.02110.0059

169IC-40

8.3.2001

198Au-60Co-56Mn-101Tc-233Pa-239Np-

69mZn-65Zn-95Zr

27.340.43 -0.00880.0062

PT3.4.2002

198Au-59Fe-56Mn-99Mo-99mTc-69mZn-

65Zn-95Zr

28.030.81 -0.01510.0068

176

IC-4016.4.2002

198Au-59Fe-116mIn-176mLu-69mZn-

65Zn-95Zr

28.740.81 -0.01130.0046

-2,0

-1,8

-1,6

-1,4

1 10 100 1000 10000 Ēr, keV

y i, r

el.

units

PT (No-169)

PT (No-176)

IC-40 (No-169)

IC-40 (No-176)PT (169): = - 0,0211

PT (176): = - 0,0151

-1,5

-1,4

-1,3

1 10 100 1000 10000 Ēr, (keV)

y i, r

el.

units

IC-40 (176): = - 0,0113

IC-40 (169): = - 0,0088

rth

rerCdrCdr G

GRFQf

,

,,,,0 1)(

ithieiiCdiCdiri GGQRFEy ,,,0,,,

_

/)(1loglog

iii bxy

N

x

x

N

yxyx

N

iiN

ii

N

ii

N

iiN

iii

2

1

1

2

11

1

N

ii

N

ii xy

Nb

11

1

Au-197 Activation in the CF, 14.5.2002

0,70

0,75

0,80

0,85

0,90

0,95

1,00

1,05

IC-10 IC-8 IC-6 IC-4 IC-2 IC-40 IC-38 IC-36 IC-34 IC-32 IC-30

Carusel channels

no

rm s

p. a

cti

v. A

u-1

98

Measured

React.Rate

MCNP

Experimental and MCNP results for thermal neutron fluence rate

Channel Experimental Total fluencerate

(MCNP)

Reactionrate

(MCNP)

Spectralratio

(MCNP)

Spectral ratio(Measured)

IC-10 0.887 0.748 0.769 37.48IC-8 0.893 0.764 0.808 36.20IC-6 0.893 0.799 0.836 35.99IC-4 0.916 0.878 0.904 34.23IC-2 0.943 0.945 1.013 32.45IC-40 1.000 1.000 1.000 29.04 28.74 0.81*IC-38 1.025 1.023 0.983 25.30IC-36 1.019 1.029 0.957 24.14IC-34 1.024 1.007 0.965 27.40IC-32 0.976 0.956 0.991 34.31IC-30 0.948 0.893 0.964 39.51

* Experimentally determined by “Cd ratio multi-monitor method”. The followingset of monitors was used: Al-Au(0.1%), Al-In(0.099%), Al-Lu(0.1%), Fe(99.9%),Zn(99.99%) and Zr(99.8%).

Comparison of experimental results for reaction rate with these of Monte Carlo calculations in 11 carousel channels at the TRIGA

reactor. Parameter f was obtained only by simulation

Temporal variation of the neutron fluence rate in the IC-40 channel

k = - 0.005

92

96

100

104

0 4 8 12 16 20Irradiation time, h

Pow

er,

%

9-9-2002 16-9-2002 23-9-20027-10-2002 6-1-2003 Avg. (safety channel)

F(t) = 1 + k·t

IrradiationPosition of

compensating rodPosition of

regulating rodSlope [1/h]

(from 5 to 20 h)9.-10.9.2002 400 from 420 to 263 k = - 0.005516.-17.9.2002 400 from 426 to 258 k = - 0.005923.-24.9.2002 400 from 418 to 231 k = - 0.00397.-8.10.2002 350 from 428 to 262 k = - 0.00506.-7.1.2003 350 from 426 to 282 k = - 0.0046

The power of the TRIGA Mark II reactor reading from the safety channel

27. and 28.1.2003

Temporal variation of the neutron fluence rate in the IC-40 channel

240

290

340

390

440

490

0 5 10 15 20 25Irradiation time, h

Ste

p of

reg

ulat

ing

rod

94

95

96

97

98

99

100

101

102

Pow

er,

%

Step of regulating rod Power

a)

94

96

98

100

102

104

450 500 550 600 650 700Step of regulating rod (looking from bottom of the core)

Pow

er,

%

b)

10

12

14

16

18

20

22

24

26

0 5 10 15 20 25Irradiation time, h

Tem

pera

ture

of

wat

er, 0

C

TH1 TH2

c)

20. and 21.1.2003

TH2: at the mean of the pool water at 0.5 m depth

TH1: at the entrance near the reactorwall at 1 m depth

Axial and radial gradients of the neutron fluence rate

A, 0-5

mm

(top)

D, 15 -2

0 mm

(botto

m)

B, 5-1

0 mm

C, 10 -1

5 mm

20

mm

1 4 m m

Fe wire = 0.4 mm

1

10

100

1000

10000

100000

0 500 1000 1500 2000

E, keV

Cou

nts

54Mn

59Fe 59Fe

Thermal neutron fluence rate: 58Fe(n,)59FeFast neutron fluence rate: 54Fe(n,p)54Mn

From the same spectrum !!!

Normalized specific activities of 59Fe and 54Mn vs. density for five matrices in the IC-40 and in the PT channels

0,94

0,96

0,98

1,00

1,02

1,04

1,06

-0,1 0,1 0,3 0,5 0,7 0,9 1,1

Density, g/cm3

Nor

mal

. 5

9 Fe

a)

Cel

lulo

se

Mus

cle

SiO

2

H2O

+1,5%

-1,5%

Air

IC-40

0,94

0,96

0,98

1,00

1,02

1,04

1,06

-0,1 0,1 0,3 0,5 0,7 0,9 1,1

Density, g/cm3

Nor

mal

. 59

Fe

b)

Air

Cel

lulo

se

Mus

cle

SiO

2

H2O

+2,3%

-2,3%

PT

0,88

0,92

0,96

1,00

1,04

1,08

-0,1 0,1 0,3 0,5 0,7 0,9 1,1

Density, g/cm3

Nor

mal

. 54 M

n

+2,6%

-2,6%

Air

Cel

lulo

se

Mus

cle

H2O

a)

SiO

2

IC-40

0,88

0,92

0,96

1,00

1,04

1,08

-0,1 0,1 0,3 0,5 0,7 0,9 1,1

Density, g/cm3

Nor

mal

. 54

Mn

+3,5%

-3,5%A

ir

Cel

lulo

se

Mus

cle

H2O

b)

SiO

2

PT

Specific activities and factors Gth, Forg and Finorg

Gth - not characteristic of nuclei, but depending ofdimensions and composition of the sample

Gth,org = 1.01 Gth,inorg = 0.97

PT IC-40 Sample Normal.

59Fe rsd, %

Total rsd, %

Normal. 59Fe

rsd, % Total rsd, %

Air 0.992 2.57 1.002 1.69 Cellulose 1.028 3.17 0.998 2.86 Muscle 1.018 3.30 1.015 2.73

SiO2 0.969 2.77 0.976 2.08 H2O 0.994 4.85

2.31

1.009 2.99

1.50

CelluloseMuscleH2O

SiO2

Axial and radial gradients of the thermal neutron fluence rate in different samples

PT IC-40

0,92

0,94

0,96

0,98

1,00

1,02

1,04

1,06

A B C DPosition, (A=top, D=bottom)

Nor

mal

. 59 F

e

Air H2O SiO2 Muscle Cellulose

a)-1.3%/cm

0,92

0,94

0,96

0,98

1,00

1,02

1,04

1,06

1,08

0 100 200 300 400 500 600Angle, 0

Nor

mal

. 5

9F

e

Air H2O SiO2 Muscle Cellulose

b)

3.8%/cm

0,92

0,94

0,96

0,98

1,00

1,02

1,04

1,06

A B C DPosition, (A=top, D=bottom)

Nor

mal

. 59F

e

Air H2O SiO2 Muscle Cellulose

a)

3.0%/cm

0,92

0,94

0,96

0,98

1,00

1,02

1,04

1,06

-200 -100 0 100 200 300 400

Angle, 0

Nor

mal

. 5

9F

e

Air H2O SiO2 Muscle Cellulose

b)

1.8%/cm

HPGe closed end coaxialdetector (OR4)40% relative efficiencyat 1332.5 keV (60Co)(dimensions are in mm)

p lexiglass

P VC tube

6 (vacuum )

2 (p lexiglass)1.27 (Al)

0 .5 (L i)

84 .0

70 .0

209 .77

89 .77

49 .77

29 .77

9 .77

L i

C rystal (Ge)

N -contact (L i)

P -contact 0 .3 m (B )

Al

65 .7

8 .8

79

.8

5 8 .0

65

.7

Geometrical correction factor for absolute calibration for detector OR4

Detector OR4

0

2

4

6

8

10

12

14

16

0K+P 1K+P 2K+P 3K+P 5K+PDistance code

Diff

eren

ce,

%

Co-57(122.1keV) Hg-203(279.2 keV) Cr-51(320.1keV)Cs-137(661.7keV) Mn-54(834.8keV) Zn-65(1115.5keV)

a)

-6,0

-4,0

-2,0

0,0

2,0

4,0

0K+P 1K+P 2K+P 3K+P 5K+PDistance code

Diff

eren

ce,

%

Co-57(122.1keV) Hg-203(279.2 keV) Cr-51(320.1keV)Cs-137(661.7keV) Mn-54(834.8keV) Zn-65(1115.5keV)

b)

-6,0

-4,0

-2,0

0,0

2,0

4,0

0K+P 1K+P 2K+P 3K+P 5K+PDistance code

Diff

eren

ce,

%

Co-57(122.1keV) Hg-203(279.2 keV) Cr-51(320.1keV)Au-198(411.8keV) Cs-137(661.7keV) Zn-65(1115.5keV)

Distance, cm

Dif

fere

nce

, %