utilization of thorium fuel in different reactor designs

Department of Engineering Physics

Tsinghua University, Beijing, China

Reactor Engineering Analysis Lab

http://reallab.ep.tsinghua.edu.cn

Utilization of Thorium Fuel in

Different Reactor Designs

YU Ganglin

Department of Engineering Physics, Tsinghua University

Reactor Eng.

Analysis Lab.

2

11/2/2012

Contents

Calculation platform for Thorium utilization

Codes

Neutron cross-section libs

Thorium in different reactor designs

Fast reactor

PWR

CANDU…

Reactor Eng.

Analysis Lab.

3

11/2/2012

Calculation Platform

With the requirement of accurate three-

dimensional modeling of the new

complex core neutronics in Thorium fuel

based reactor physics analysis and great

innovation of computer technology,

Monte Carlo method is becoming a more

powerful tool for core analysis and

receiving the rising attentions

Reactor Eng.

Analysis Lab.

4

11/2/2012


Monte Carlo method has been used for criticality safety analysis,

shielding and dosimetry calculations, and the MC results are often

used as benchmarks to validate deterministic transport codes.

- Advantages:

1. flexibility in geometry treatment

2. both point-wise and multi-group neutron cross sections

can be used

3. calculation time independent with problems’ dimension

4. easy to parallel

- Disadvantages:

1. more time cost than deterministic methods

2. results are random variables

Reactor Eng.

Analysis Lab.

5

11/2/2012


Reactor MC Code RMC for thorium reactor

Motivation

General Introduction of RMC

Some Current R&D Progress on RMC

• Parallel

• Burnup Calculation

Temperature dependent neutron cross-

section data

RXSP code

libs

Conclusions

Reactor Eng.

Analysis Lab.

6

11/2/2012


Motivation

New conceptual and advanced thorium fuel reactors:

complex geometry and neutron spectrum

Development of computer technology

In-house code is easier to be modified and improved

than production codes

Typical production code such as MCNP does NOT

meet some requirements of reactor analysis

NOT easy to get the updated MCNP and its source

code in China

Reactor Eng.

Analysis Lab.

7

11/2/2012


Introduction

RMC is a Monte Carlo neutron transport code being

developed by Department of Engineering Physics,

Tsinghua University, which is specifically intended to

reactor analysis. The Beta version of RMC has been freely

limited released in September 2012.

Based on about 6 years’ basic and preparative research,

the full programming of RMC started in 2008, and it’s

written in C++. The total manpower is more than 30

person-years.

To meet the requirements of reactor core analysis, RMC

has been integrating some methods/techniques to

improve efficiency and to enhance capabilities after the

required basic functions being realized.

Reactor Eng.

Analysis Lab.

8

11/2/2012


Parallel

WHY:

MC method time-consuming

Billions of particles required for pin power

calculations in full core analysis, and thus

large memory required

embarrassing parallel techniques used in

certain current code

Reactor Eng.

Analysis Lab.

9

11/2/2012


RMC Parallel Strategy

Master-slave mode

Traditional MC codes, such

as MCNP

Peer mode

RMC

Reactor Eng.

Analysis Lab.

10

11/2/2012


Parallel Performance of RMC

Large scale parallel full core calculations of RMC

NEA Monte Carlo Performance Benchmark with

continuous energy (pointwise) cross sections

Edf Benchmark with multi-group (8, 26) cross sections

Reactor Eng.

Analysis Lab.

11

11/2/2012

Large scale parallel full core

calculations of RMC

Reactor Model

J.E. Hoogenboom, W. R. Martin and B. Petrovic, “ Monte Carlo Performance

Benchmark for Detailed Power Density Calculation in a Full Size Reactor Core ” Benchmark specifications Revision 1.2, July 2011; http://www.nea.fr/dbprog/MonteCarloPerformanceBenchmark.htm.

Reactor Eng.

Analysis Lab.

12

11/2/2012


calculations of RMC

Computing Platform

Explorer 100, Tsinghua HPC Platform (2011)

CPU: Intel Xeon X5670 (2.93GHz, 12MB Cache)

Ranking No.1 in Chinese universities (2011)

TOP500 List - June 2012 (201-300) -- http://www.top500.org/list/2012/06/300

Rank Site Computer Cores Rmax Rpeak

211 Tsinghua University Inspur TS10000 HPC Server 9216 92.42 107.30

Rmax and Rpeak values are in Tflops.

Reactor Eng.

Analysis Lab.

13

11/2/2012

Reactor Eng.

Analysis Lab.

14

11/2/2012


calculations of RMC

Multi-cores Comparisons

MCNP RMC MCNP RMC MCNP RMC

CPUs Time(min) Time(min) Speedup Speedup Efficiency Efficiency

1 3976.12 2352.34 1 1 100.00% 100.00%

24 187.58 110.69 21.20 21.25 88.32% 88.55%

60 79.70 44.36 49.89 53.03 83.15% 88.38%

120 47.75 22.48 83.27 104.64 69.39% 87.20%

240 35.54 11.43 111.88 205.80 46.62% 85.75%

300 32.94 9.27 120.71 253.76 40.24% 84.59%

360 32.58 7.77 122.04 302.75 33.90% 84.10%

480 36.60 5.87 108.64 400.74 22.63% 83.49%

600 54.71 4.74 72.68 496.27 12.11% 82.71%

720 77.58 3.98 51.25 591.04 7.12% 82.09%

840 91.75 3.43 43.34 685.81 5.16% 81.64%

condition: kcode 3,000,000 1.0 100 300

Reactor Eng.

Analysis Lab.

15

11/2/2012


calculations of RMC

Speedup

0 200 400 600 800 1000

-100

0

100

200

300

400

500

600

700kcode 3,000,000 1.0 100 300

Sp

ee

du

p

CPUs

MCNP

RMC

Reactor Eng.

Analysis Lab.

16

11/2/2012


calculations of RMC

Effects of the number of Tallies

Tally is very important to

full core analysis with

pin flux/power.

Computing time of MCNP

is proportional to the

number of tallies, while

RMC is not sensitive

owing to cell mapping

method.

Tallies

Time (minutes)

MCNP5_1.14 RMC

0 6.48 3.7

15 8.02 3.99

594 14.38 4.13

1715 28.58 4.25

26415 440.25 4.46

106898 1781.63 4.81

kcode 50,000 1.0 100 600

24 threads

Reactor Eng.

Analysis Lab.

17

11/2/2012


Burnup

RMC Burnup Features

High accuracy and efficiency

Large scale burnup problems

friendly user interface

RMC Burnup method

Energy-bin for multiple nuclides, cell-mapping for multiple

cell tallies, one-batch for parallel speedup

More than 1300 nuclides, matrix exponential methods

Inner coupling

Reactor Eng.

Analysis Lab.

18

11/2/2012


Burnup of RMC

Case 1: PWR pin

Reactor Eng.

Analysis Lab.

19

11/2/2012


Case 1: PWR pin

Isotope CASMO RMC Diff from

CASMO (%)

Mo-95 7.08E+19 7.13E+19 0.79

Tc-99 7.64E+19 7.46E+19 -2.35

Ru-101 8.44E+19 8.53E+19 1.04

Rh-103 3.34E+19 3.36E+19 0.53

Cs-133 7.73E+19 7.75E+19 0.29

Cs-135 2.66E+19 2.68E+19 0.66

Nd-143 2.54E+19 2.55E+19 0.45

Nd-145 3.94E+19 3.99E+19 1.26

Sm-147 4.58E+18 4.51E+18 -1.46

Sm-149 5.01E+16 5.07E+16 1.16

Sm-150 1.88E+19 1.91E+19 1.51

Sm-151 3.06E+17 3.09E+17 0.93

Sm-152 6.29E+18 6.45E+18 2.45

Eu-153 8.04E+18 8.02E+18 -0.25

U-234 1.15E+17 1.17E+17 1.38

U-235 4.84E+18 4.77E+18 -1.49

U-238 2.07E+22 2.07E+22 -0.11

Np-237 1.41E+19 1.41E+19 -0.12

Pu-238 7.90E+18 8.05E+18 1.91

Pu-239 1.08E+20 1.08E+20 0.18

Pu-240 6.10E+19 6.19E+19 1.34

Pu-241 3.05E+19 3.08E+19 1.01

Pu-242 4.15E+19 4.17E+19 0.52

Am-241 9.99E+17 9.82E+17 -1.64

Am-243 1.27E+19 1.30E+19 2.40

Reactor Eng.

Analysis Lab.

20

11/2/2012


Burnup of RMC

Case 2: PWR 5×5 assembly sets(6600 independent

Burnup regions )

Reactor Eng.

Analysis Lab.

21

11/2/2012


Burnup of RMC

Case 2: PWR 5×5 assembly

Reactor Eng.

Analysis Lab.

22

11/2/2012


Neutron Cross Section Code and Libs

WHY - Motivations:

Vital importance of the accuracy of temperature-

dependent cross-section data to thorium fuel

neutronics analysis.

Ever-changing temperatures and hundreds of

nuclides in thorium reactor N-TH coupling

calculations.

NJOY, AMPX can’t meet requirements due to the

long computational time.

Reactor Eng.

Analysis Lab.

23

11/2/2012


On-the-fly high efficiency parallel cross sections processing

How to do:

RXSP code

Pre-generation of 0K ACE cross sections from

ENDF.

Fast Doppler Broadening (FDB) – numerical

integrals and parallel computation, to generate

ACE continuous energy XSs at the target

temperature points.

Temperature interpolations of thermal cross

sections.

Reactor Eng.

Analysis Lab.

24

11/2/2012


RXSP procedure ( similar to NJOY )

Reactor Eng.

Analysis Lab.

25

11/2/2012


Parallel

Doppler Broadening

零温度能量框架

分段 1 分段 2 ………… 分段 N

线程 1 线程 2 ………… 线程 N

展宽后的能量框架

选取初始能量框架

Reactor Eng.

Analysis Lab.

26

11/2/2012


600K U238 (n, tot) cross sections

RXSP VS NJOY

Reactor Eng.

Analysis Lab.

27

11/2/2012


What effects - Processing Time(sec)

FDB (with 12-cores parallel) VS NJOY

nuclide Broadr+Acer

Time

NJOY

Total Time

FDB Time Speedup-A Speedup-B

U238 38.6 231.0 2.086 18.50 110.74

U235 23.6 192.9 1.442 16.37 133.77

U233 4.2 12.7 0.37 11.35 34.32

Th232 39.1 60.2 1.102 35.48 54.63

Pu239 18.9 34.1 0.984 19.21 34.65

Pu240 8.2 12.1 0.531 15.07 22.79

Reactor Eng.

Analysis Lab.

28

11/2/2012


Temperature-dependence Neutron Cross section Libs

Based on ENDF/B lib

ENDF/B6.8 ( 321 nuclides )

ENDF/B7.0 ( 393 nuclides )

ENDF/B7.1 ( 423 nuclides)

16 temperature points

294K to 2400K

ACE format

compatible to MCNP and RMC

Reactor Eng.

Analysis Lab.

29

11/2/2012


Difference of Th232 data between ENDF/B6 and ENDF/B7

The difference of calculation result on pin cell

model

-2.500%

-2.000%

-1.500%

-1.000%

-0.500%

0.000%

0 2 4 6 8 10 12

Th232和U235的原子比

相对偏差

修改栅格比后的快堆计算结果快堆计算结果

Thermal spectrum Fast spectrum

Reactor Eng.

Analysis Lab.

30

11/2/2012


Difference of Th232 data between ENDF/B6 and ENDF/B7

The difference of cross section between two

libs Absoption cross section Neutron released per fission

Reactor Eng.

Analysis Lab.

31

11/2/2012


Conclusions

Code and Lib

RMC for neutronics

calculations

RXSP for Lib generating

RXSP + RMC Combined

system has been used in

thorium fuel based reactor

design

Input file

of RMC

TRMC

New Input

file of RMC

New ACE

libraries

RMC

Thermal-

hydraulics code

FDB

Reactor Eng.

Analysis Lab.

32

11/2/2012

Thorium in different reactor

Thorium fuel in different reactor

Advantages of Thorium fuel in reactor

physics

Our research work on different reactor

designs

Thorium based small fast reactor

Thorium in PWR

Others…

Reactor Eng.

Analysis Lab.

33

11/2/2012


Thorium based long-life fast reactor

Thorium(Th232) is a fertile nuclide and U233 is a fissile nuclide The current application of thorium: laboratory

scale, not industry scale.

More abundant, supplement for Uranium fuel

Many thermal reactor designs, such as HTGR, CANDU…

In fast reactor, traditionally Thorium is used as Breeding nuclide

Reactor Eng.

Analysis Lab.

34

11/2/2012


Thorium based long-life fast reactor

Thorium-Uranium fuel could be used in fast

reactor as fuel

U233 has a good fission capability

The η of U233 is slightly less than Pu239 in hard

spectrum, larger than Pu239 in an intermediate

spectrum and a soft fast spectrum

The fission cross section is much larger than

Pu239

Reactor Eng.

Analysis Lab.

35

11/2/2012

Thorium long-life fast reactor

Fission cross section of U233, Pu239

Reactor Eng.

Analysis Lab.

36

11/2/2012


Long-life Core Design

The technical options and principles of physical

design of the existed long-life core

Plutonium – Uranium oxide

Triangle pincell, compact geometry

Small P/D ratio

Sodium, lead, lead-bismuth coolant

large neutron leakage

For a traditional long-life core

A high initial conversion ratio (>1.1)

A long core life (>10 years or >80000 MWt/tHM)

The CR will decrease with burnup

Influence greatly the reactivity swing with burnup

Reactor Eng.

Analysis Lab.

37

11/2/2012


Advantages of U233

Better fissile capability

The advantage increases with a soften

spectrum or a low enrichment

Benefit to design a negative void coefficient

Low neutron fluence with the same specific

power

Increase the life of cladding in the same burnup

Reactor Eng.

Analysis Lab.

38

11/2/2012


Advantages of Thorium fuel

Consider the mixed fuel of thorium and spent fuel Pu

New produced U233 will compensate the reactivity lost from Pu239 and Pu241 with burnup even if the conversion ratio smaller than 1

Decrease the demand to conversion ratio

Increase the P/D ratio to enhance the natural circulation ability

Reactor Eng.

Analysis Lab.

39

11/2/2012


Sketch in X-Z cross section

39

Main parameter （cm）

Core central diameter 40

Core outer diameter 200

Outer wall diameter 320

Outer coolant thickness 10

Inner wall thickness 5

Down comer thickness 35

Outer wall thickness 10

Core height 200

Gas plenum height 150

Reactor Eng.

Analysis Lab.

40

11/2/2012


Fuel Rod Design

Fuel Thorium- spent fuel Pu

Plutonium in mixed fuel 18 %

Density 9.8 g/cm3

Fuel type Oxide

Fuel pellet diameter 10.0 mm

Fuel rod diameter 12.5 mm

Lattice square

Pitch to diameter ratio 1.5

Fuel rod length 200 cm

Fission gas plenum length 150 cm

Coolant 45.5% Lead + 55.5%

Bismuth

Coolant density 10.5 g/cm3

nuclide percent

Pu238 2 %

Pu239 61 %

Pu240 24 %

Pu241 10 %

Pu242 3 %

Reactor Eng.

Analysis Lab.

41

11/2/2012


Codes and Data Libs

RMC

criticality calculation

RMC + MCBurn

Burnup calculation

RXSP

Cross-section lib

The temperature-dependent cross-section library

comes from ENDF/B6.8.

Reactor Eng.

Analysis Lab.

42

11/2/2012


Physics characteristics

parameter BOL EOL

Conversion ratio 1.0896 0.9530

Keff 1.00771 1.01998

Power（MWt） 138 138

Ave. burnup（MWd/tU） 0 90000

Peak burnup（MWd/tU） 0 166500

Specific power（w/g） 10 11

Ave. flux（n cm2s-1） 4.43 E+14 4.17 E+14

（>0.1Mev）fast flux 56.5% 57.3%

Peak fast fluence（n cm2） 0 3.48E+23

Peak power factor 1.882 1.825

Average linear power (W/cm) 76.9 76.9

Temperature coefficient (300-900K)(dk/kk ℃)

-1.495E-5 -1.002E-5

Void coefficient

(dk/kk ％void)

1.696E-5 -1.938E-5

Reactor Eng.

Analysis Lab.

43

11/2/2012


Physics characteristics

High burnup

Nearly zero reactivity swing with burnup

Large P/D ratio

Square geometry

P/D ratio = 1.5

Full power natural circulation

Lower neutron fluence

Reactor Eng.

Analysis Lab.

44

11/2/2012


Reactivity swing with burnup Spectrum

0 20000 40000 60000 80000 100000 120000 140000

0.990

0.995

1.000

1.005

1.010

1.015

1.020

1.025

1.030

1.035

1.040

Ke

ff

Burnup (MWd/Tu)

Keff

1E-4 1E-3 0.01 0.1 1 10

-0.002

0.000

0.002

0.004

0.006

0.008

0.010

0.012

0.014

Flu

x (

n/c

m2s)

Energy (Mev)

BOL

EOL

Reactor Eng.

Analysis Lab.

45

11/2/2012


Fissionable Nuclide Enrichment

0 20000 40000 60000 80000

12.0

12.2

12.4

12.6

12.8

13.0

13.2

13.4

Enr

ichm

ent (

%)

Burnup (MWd/Tu)

Enrichment

Nuclide BOL EOL

Th232 2.50% 2.04%

U233 0.00% 52.16%

Pu239 74.56% 32.93%

Pu240 5.89% 5.38%

Pu241 17.05% 7.48%

Enrichment with burnup

Fission fraction with different nuclide

Reactor Eng.

Analysis Lab.

46

11/2/2012


The model to Calculate Void Coefficient

The core is divided to eight parts in radial direction

Reactor Eng.

Analysis Lab.

47

11/2/2012


Void Coefficient in 8 parts

Void position

BOL (dk/kk void%)

EOL(dk/kk void%)

Full core 1.696E-05 -1.938E-05

Circle 1 4.876E-05 3.117E-05

Circle 2 4.455E-05 2.323E-05

Circle 3 2.690E-05 -2.117E-06

Circle 4 7.601E-06 -1.735E-05

Circle 5 -2.965E-06 -2.170E-05

Circle 6 -1.454E-05 -3.418E-05

Circle 7 -2.794E-05 -3.457E-05

Circle 8 -3.291E-05 -3.021E-05

0 1 2 3 4 5 6 7 8 9

-4.0x10-5

-3.0x10-5

-2.0x10-5

-1.0x10-5

0.0

1.0x10-5

2.0x10-5

3.0x10-5

4.0x10-5

5.0x10-5

6.0x10-5

Vo

id C

oe

ffic

ien

t (d

k/k

k v

oid

%)

Circle Number

BOL

EOL

Reactor Eng.

Analysis Lab.

48

11/2/2012


Comparison of different designs

4S long-life SVBR ENHS Th-based

Fuel Spent Pu - U8 U5 – U8 Spent Pu - U8 Spent Pu – Th2

Fuel type U-Pu-Zr oxide U-Pu-Zr Oxide

Enrichment 24％ 15.6％ 12％ 18％

Coolant sodium Lead-Bismuth Lead-Bismuth Lead-Bismuth

Thermal Power 30 MWt 268 MWt 125 MWt 138 MWt

Specific power 7 W/g 28 W/g 7 W/g 10 W/g

life a 30 8 20 25

Ave. Burnup MWd/tHM

76000 82600 50800 90000

Reactivity swing yes yes no no

Reactivity compensate

reflector Control rod none none

P/D ratio (triangle)

1.15 1.15 1.36 1.5

(square)

Reactor Eng.

Analysis Lab.

49

11/2/2012


Conclusions

Th-U fuel can be used in long-life core reactor design U233 has some good characteristics in mediun

and fast neutron spectrum

Thorium fuel can solve the problem of CR decrease in long-life core

Thorium fuel will benefit a longer life design for its lower neutron fluence

The conceptual design of THLS have been done preliminarily.

Reactor Eng.

Analysis Lab.

50

11/2/2012

Thorium fuel PWR

PWR is the most important reactor now

Great amount

Commercial competitiveness

Thorium fuel can be used in PWR

Feasible

To improve the thorium utilization rate

To compare with many existing research work

Reactor Eng.

Analysis Lab.

51

11/2/2012

Thorium fuel PWR

Calculation model

lattice Fuel assembly

¼ assembly Different

thorium fuel

rod design

¼ core model

Reactor Eng.

Analysis Lab.

52

11/2/2012

Thorium fuel PWR

2.U-235 as driven fuel ( enrichment

3.1%、4.5%、5%、6.2%、8%、10%)

3.RMC + RXSP

Step 5 10 15 20

Burnup (GWD/THM)

1.36 9.35 17 25.5

Time(Day) 50 300 550 800

4.Calculation conditions

1.Different designs

Reactor Eng.

Analysis Lab.

53

11/2/2012

Thorium fuel PWR

Thorium fuel will decrease the

reactivity swing

Separated fuel model is better

than mix model in reactivity

Comparison result

Reactor Eng.

Analysis Lab.

54

11/2/2012

Thorium fuel PWR

The thorium fuel rod should be evenly distributed in the assembly

Comparison result

Reactor Eng.

Analysis Lab.

55

11/2/2012

Thorium fuel PWR

Different thorium load Different enrichment

Central vs outer Mix vs seperate

Thorium

utilization

ratio in

different

conditions

Reactor Eng.

Analysis Lab.

56

11/2/2012

Thorium fuel PWR

The temperature and void coefficient are negative

Temperature coefficient and void coefficient

Reactor Eng.

Analysis Lab.

57

11/2/2012

Thorium fuel PWR

Whole core calculation results

Reactor Eng.

Analysis Lab.

58

11/2/2012

Thorium fuel PWR

The utilization of thorium

fuel will not influence the

core power distribution

Core power distribution

Reactor Eng.

Analysis Lab.

59

11/2/2012

Thorium fuel PWR

Thorium consumption rate

vs burnup

Assembly burnup

（GWD/THM）

Th-232 consumption

rate（%）

1 3.821448035108E+01 4.445586638509E-02

2 3.144859027350E+01 3.580464559426E-02

3 3.346989964178E+01 3.835083636990E-02

4 4.603312339346E+01 5.490931719089E-02

5 5.402349175090E+01 6.609764239474E-02

7 3.511177180668E+01 4.044311788430E-02

8 5.153506013862E+01 6.255850983258E-02

12 3.406423778960E+01 3.910572697435E-02

18 2.719003809769E+01 3.054723078471E-02

19 4.952190300969E+01 5.973157852049E-02

25 3.921350346998E+01 4.576429888754E-02

32 3.436820528420E+01 3.949289942203E-02

33 4.560013542013E+01 5.431762482147E-02

40 5.252520951198E+01 6.396080004909E-02

Avg. 5.196462270088E-02

Th-232 consumption rate for all assembly

Reactor Eng.

Analysis Lab.

60

11/2/2012


Other thorium reactor designs

CANDU

Super critical water reactor

Traveling wave reactor

Fusion-fission hybrid reactor

Reactor Eng.

Analysis Lab.

61

11/2/2012


Conclusions

Thorium fuel has some special advantages in

some reactor designs

The utilization of thorium will not influence

the safety of traditional reactor

U233 is the best fissile nuclide both in

thermal and fast neutron spectrum

Thorium can be used in different reactor

Need to determine a best way

Thanks !

utilization of thorium fuel in different reactor designs

Documents