Optimization of Radioisotopes Production in an MTR-type Core T. - - PowerPoint PPT Presentation

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Core Elements Improvements for Optimization of Radioisotopes Production in an MTR-type Core

• T. Makmal1,2, M. Alqahtani2, A. Buijs2, J. Luxat2

1) Nuclear Physics and Engineering Division, Soreq Nuclear Research Center, Yavne, Israel 2) Engineering and physics department, McMaster University, Ontario, Canada

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PART I: INTRODUCTION

2 Core Elements Improvements

• The primary purpose of Research Reactors is to provide a neutron source for

research in natural sciences, industrial processing and nuclear medicine.

• The most common method for isotopes production is by the neutron

activation process.

• Due to the cosine shape of the flux in every axis, the maximal flux length is

located around the center of the active length of the Fuel Assembly (FA).

• This limited area of maximal flux makes the activation process of large or

multiple samples less efficient.

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PART II: THE OBJECTIVE OF THIS STUDY

3 Core Elements Improvements

• Analyzing the main components in isotope production process in order to
• ptimize the production by uniform and flat thermal flux.
• Re-design components:
• Irradiation Position (IP) body material.
• FA linear fuel distribution loading.
• Carry out a production rate comparison

between MNR FA to the modified FA.

IP “Body Material” Inner cylinder for irradiation samples Standard MTR FA

• 3-D, Monta-Carlo Simulations of MTR fuel-type mini-core.
• The thermal flux, along the active length, of the inner cylinder was detected. The

values were analysed and compared.

THE METHODOLOGY

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PART II: FLUX IMPROVEMENTS (1/4)

4 Core Elements Improvements xy-plot of the mini-core. xy-plot of the mini-core – mesh image. yz-plot

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PART II: FLUX IMPROVEMENTS (1/4)

5 Core Elements Improvements

Changes in the IP body material

• Five principal materials simulated to analyse the change in flux shape.

8,6E+13 8,7E+13 8,8E+13 8,9E+13 9,0E+13 9,1E+13 9,2E+13 9,3E+13 1,70E+13 1,75E+13 1,80E+13 1,85E+13 1,90E+13 1,95E+13 2,00E+13 2,05E+13 2,10E+13 10 20 30 40 50 60

Thermal Flux [n/cm2/sec]

Thermal Flux [n/cm2/sec] Active length [cm]

Case#4 IP - Be Case#4 IP - HWT Case#4 IP - GRA Case#4 IP - He Case#4 IP - LWT

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PART II: FLUX IMPROVEMENTS

6 Core Elements Improvements

Changes in the linear atom density

• The U-235 atom density change will be achieved by increasing the number of

U3Si2 molecules per cc without changing the enrichment of the.

• Different cards were built with Uranium densities between 3.735 to 5.478 gU/cc.
• At very high loadings the aluminum ceases to play a significant role, and

the thermal conductivity approaches that of the fuel (15[W/mK]), which indicates stopping criteria for additional high density card.

Card # U235 mass in each plate [gr] Total U235 mass in a FA [gr] U235 density in a plate [gU235/cc] U density in a plate [gU/cc]

Thermal Conductivity [W*m/K]

1 14.0625 225 0.737 3.735 77.70 2 15.0000 240 0.786 3.984 66.39 3 15.9375 255 0.836 4.233 55.68 4 16.8750 270 0.885 4.482 45.81 5 17.8125 285 0.934 4.731 37.06 6 18.7500 300 0.983 4.980 29.81 7 19.6875 315 1.032 5.229 24.48 8 20.6250 330 1.081 5.478 21.60

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PART II: FLUX IMPROVEMENTS

7 Core Elements Improvements

Changes in the linear atom density:

• Using the different loadings Cards, a new fuel (Case) was built.
• Each FA was split into seven sub segments (8.5714cm each).
• Eight different Cases were simulated. All analysed and compared.
• The most efficient cases, in terms of high and flat flux, were chosen.

Sub-segment # Fuel atom density [grU/cc] Thermal Conductivity [w*m/K] Fuel atom density [grU/cc] Thermal Conductivity [w*m/K]

Case #4 (MNR standard FA) Case #7 1 3.735 77.70 4.731 37.06 2 3.735 77.70 4.233 55.68 3 3.735 77.70 3.984 66.39 4 3.735 77.70 3.735 77.70 5 3.735 77.70 3.984 66.39 6 3.735 77.70 4.233 55.68 7 3.735 77.70 4.731 37.06 Card5# Card5# Card3# Card3# Card2# Card2# Card1# Case#7

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PART II: FLUX IMPROVEMENTS

8 Core Elements Improvements

Changes in the linear atom density and the IP body material:

8,6E+13 8,7E+13 8,8E+13 8,9E+13 9,0E+13 9,1E+13 9,2E+13 9,3E+13

10 20 30 40 50 60

Thermal Flux [n/cm2/sec] Active length [cm] Case#4 IP - LWT Case#7 IP - LWT

1,80E+13 1,82E+13 1,84E+13 1,86E+13 1,88E+13 1,90E+13 1,92E+13 1,94E+13 1,96E+13

10 20 30 40 50 60

Thermal Flux [n/cm2/sec] Active length [cm] Case#4 IP - Be Case#7 IP - Be

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PART III: PRODUCTION RATE COMPARISON

9 Core Elements Improvements

• To present the benfit of the suggested FA in comparison to the known MTR

FA, calculation of Iridium-192 seeds production carry out.

• The objective is to evaluate, by calculations, the productions of uniform

activity Ir-192 seeds.

• Using the well known activation equation, the activity of 60 seeds calculated.
• The irradiation time set according to the center seed approaching to the

activity target (200mCi).

• A strict quality check disqualifies seeds if their activity is outside of 1% from

the activity target .

൯ 𝐵 𝐷𝑗 = Ν ∙ 𝜏 ∙ 𝜚 ∙ (1 − 𝑓−𝜇𝑢

25 60 24 60 23 60 10 20 30 40 50 60 70 Case#4 Case#7 Case#4 Case#7 Case#4 Case#7 GRA GRA Be Be HWT HWT

# of accepted seeds in 24 hr shift

118 334 50 100 150 200 250 300 350 400 Case#4 Case#7 LWT LWT

# of accepted seeds in 24 hr shift

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PART IV: THERMAL-HYDRAULIC CALCULATION

10 Core Elements Improvements

• Calculations of lower thermal conductivity (higher fuel atom density) show not

much difference in the temperatures profile along an axial fuel plate.

• Explained by the Biot number, Bi = h ∙

𝑒 𝑙 , the fuel thickness is not thick enough

to get heated.

• The heat capacity of the fuel meat decreases from 2.44 to 2.13 [MJ/m*K] as the

fuel volume fraction (fuel+voids) increases from 0 to 0.5. The decrease is a result of the increase in porosity as the fuel volume fraction increases, since the volumetric heat capacities of aluminum and U3Si2 are very similar.

• Safety analysis calculations for Onset Nucleate Boiling and Pump Failure show

no significant difference comparing to MNR standard FA calculations values.

(~3.7grU/cc) (~4.7grU/cc)

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PART IV: KEFF AND BURNUP CALCULATIONS

11 Core Elements Improvements

• For reliable running, each simulation done with 50000 particles, 5000 active

and 250 inactive cycles.

• The absolute error in the Keff was found to be <0.07mK and therefore neglected.
• In terms of the successful continuity operation, 16 cycles of five days each

were preformed.

• The core become sub-critical only after 50 days of operation.

1,546 1,540 1,542 1,457 1,571 1,564 1,567 1,482 1,38 1,4 1,42 1,44 1,46 1,48 1,5 1,52 1,54 1,56 1,58 Be GRA HWT LWT Be GRA HWT LWT 4 4 4 4 7 7 7 7

Keff Different Cases

1,00 1,10 1,20 1,30 1,40 1,50 1,60 5 10 15 20 25 30 35 40 45 50 55 60 65 70

IMP keff Operating Days Case#7_Be Case#7_LWT Case#4_LWT

558 676 2207

500 1000 1500 2000 2500

Case#7 Case#4 Case#7 Be LWT LWT # of acceepted seeds in cycle

25days 55days 65days

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PART IV: SUMMARY AND CONCLUSIONS

12 Core Elements Improvements

• In this scoping study a new design of MTR FA analyse in order to optimize

isotope production at MTR type RRs.

• Components impact:
• IP body material changes the flux amplitude.
• Linear fuel distribution changes the flux shape.
• In comparison a full cycle, by using the re-design models, the cycle length

increases by 120% and the radioisotopes production increases by 230%

• Except LWT, no significant different found between the IP body materials, in

terms of production rate and the Keff .

• Thermal-Hydraulic calculations and a safety analysis for the selected cases

shows safe operations comparing to an MNR safety analysis report.

• This new design can be cost effective in terms of radioisotopes production

and fuel.

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THANK YOU!

14 Core Elements Improvments

Questions?