tmsr physical design of photo-neutron source based on 15 ... · rpd 1 the requirement of ... study...

TMSR

Reactor Physics Division

钍基核能系统

Physical design of photo-neutron source based on 15 MeV Electron Linac accelerator and Its Application

10/2012

on behalf of

Reactor Physics Division of TMSR

Nuclear Physics Division

WANG Hongwei

Shanghai INstitute of Applied Physics(SINAP), Chinese Acaedy of Science(CAS)

TMSR

Reactor Physics Division

Contents

1. The requirement of nuclear data for TMSR

2. Monte Carlo Calculation

3. Neutron target

4. Detection system

5. Summary

Thorium-Based Molten Salt Reactor System Reactor Physics Division

RPD 1 The Requirement of Nuclear Data For TMSR

High accuracy fission cross section data for some 232Th and U

isotopes(233,234,236U) are important for the development of the Th-U

fuel cycle for energy production.

High accuracy neutron capture cross section data are needed to

address some still-open questions in fundamental, Reactor Physics and

nuclear astrophysics.

Precise measurements of neutron cross section are of great

importance for the safety design and for the evaluation of neutron flux

density and energy spectrum around a reactor


RPD Scheme of Thorium-Uranium cycle


RPD Learn from the Scheme

the most impotant decay channels in this cycle are

β- and decay in the last decay chains

the cross section related with the most important

reactions must be located in a good precision of an

order of few percent(5-10%),but many data shows

large discrepances or large uncertainty


RPD

For example:

For 232Th(n,γ) capture reaction, it shows that discrepancy among data

published is around 20-30%, sometimes for neutron energies above 50keV,

some new data have been corrected by accurately measured recently.

The nucleus 233Pa(protactinium) plays a key role in Th cycle and acts as a

precursor to the long lived fissile nucleus 233U, the half life of 233Pa(27d) is

rather long，it open a possibility to capture neutron in the reactor. So far no

reliable data exist (was available) for the cross section of this reaction,

moreover those data at some energies differ by almost a factor two.


RPD

Fe，Cr，Ni，Mo

155、157Gd，10B, O，Al

135Xe，149、151Sm，133Cd，6Li，Te

231、232、233Th，233、234Pa，233U，Be，F，Na，7Li Fuel salt

Reactor poison

Alloy

Control rod

Other related nuclei


RPD

Status of the Key Nuclear Data in TMSR

The lack of nuclear data

Full set of data：234Pa

…….

Fission yield data：

233Pa、233Th、232U

……

Differences of nuclear data

Full set of data：232Pa、

234U、

…….

Fission yield

data：

131I、135I、135Xe

……

Updated nuclear data

Full set of data：232Th、233U、155Gd

……

Fission yield

data：

233U、

232Th

…..

Activa-tion

data：233Pa、

233Th

…..

Decay data： 231Th、 232U、 233Pa

Measurement system and

the method of measure-

ment development！！！

Reso

lved

Me

tho

ds

Improved evaluation

method

Improved equipment

performance

Improved measuring

method


RPD

2012/11/2 9

XS Energy range Evaluation data Exp data Note

U-233(n,f) 10-200eV JENDL-4.0 more wide in

Resonance energy area

Above 500eV Differences of evaluation

data

U-233(n,g) 5-50eV JENDL-4.0 more wide in

Resonance energy area Larger error

Above 500eV Differences of evaluation

data

Th-232(n,g) 10eV-5KeV fewer experimental data

Th-232(n,f) Below 60KeV JEFF-3.1 without evaluation data

1-500KeV Larger error

Pa-233 (n,g) Thermal neutrons and

several fast neutron Better agreement Y

No other energy

experimental data

Pa-233 (n,f) Below 1MeV The lack of JEFF-3.1 N

Th-233(n,g) Only thermal neutrons Better agreement Y No other energy

experimental data

Th-233(n,f） 1eV-10keV Differences of ENDF/B and JEFF Only 0.0253eV No other energy

experimental data

Pa-234 Only TENDL N

Xe-135 (n,g) Above 50eV Differences of all data librarys Only 0.0253eV and 318eV No other energy

experimental data

The summary of status

钍铀燃料物理 2012/11/2

The Way to Produce Neutron


RPD

From this table, we find the photo-neutron source is a powerful tool to

produce intense pulsed neutrons, it are effective for measuring energy

dependent XS with TOF technics, the energy range from thermal neutrons to a

few tens of MeV.

Until now, No photo-neutron source be build in China.

TOF facility in the world

钍铀燃料物理 2012/11/2

Principle of photo-neutron source

12

Electron bombs the target which made by heavy elements, γ rays produced through bremsstrahlung reaction, then neutrons emit from target by (γ, n) reaction.

W. P. Swanson, “Radiological Safety Aspects of the operation of Electron Linear

Accelerators,” IAEA Tech. Rep. 188 (1979)

Empirical formula


RPD

Neutron yield as a function of electron energy for different element

Candidates : U，W，Pb，Ta，Au

Electron energy above 30 MeV, neutron yield

approaches a saturated value, and neutron yield

of W higher than Ta target.

taken from Reference


RPD

2012/11/2 2012/11/2 14

Our consideration of nuclear

data measurement priority

钍铀燃料物理 2012/11/2

Plan for nuclear cross section measurement

15

Measurement for total and resonance cross section from thermal to slow neutron,

dividing two steps:

First step 15 MeV electron LINAC produces neutron, located at Jiading campus,

SINAP

Neutron yield ~1011 n/s

TOF path ~ 5m

Second step for fast neutron 100 MeV electron LINAC, in Future

Neutron yield ~1012 n/s

TOF path ~ 10-50m

钍铀燃料物理

Why choose 15MeV electron linac as driving facility?

Produce white light neutron, for the required neutron cross section

related with TMSR at thermal and slow neutron energy

Preparing technique for building high energy electron linac accelerator

based photo-neutron source

Study Irradiation effect of neutron and gamma on TMSR material,

organism and detectors

The advantage:

Build up a 15MeV accerelator in a short time based on our prior electron linac

technique, will be easy to extend to high energy.

Exist a suitable neutron experimental hall, Save time, but space limited!


RPD

Comparison with other neutron source facility based on the electron LINAC

钍铀燃料物理

Neutron source streng calculated by MCNP

15 MeV electron + target Tungsten target Tantalum target

Neutron Yield（n/e） 6.1646E-04 6.928E-4

Photon Yield (photon/e) 33.673 32.408

15 MeV electron /Tantalum 2 kW(Normal) 7.5 kW(Max)

Neutron yield（n/s） 5.53E+11 2.16E+12

Photon yield（p/s） 7.76E+14 2.03E+17

15 MeV electron/Tungsten 2 kW(Normal) 7.5 kW(Max)

Neutron yield（n/s） 5.04E+11 1.89E+12

Photon yield（p/s） 6.30E+14 2.36E+15

2 Monte Carlo Calculation

Neutron yield calculated by MCNP for beam power 2kW and 7.5kW

钍铀燃料物理 2012/11/2

Neutron & photon flux（n/s/cm2) at 90 direction

relative to electron beam

15MeV Electron(2kW )+W 0.5m/(n/s/cm2) 5m/(n/s/cm2)

Neutron 1.51E+07 1.43E+05

Photon 1.81E+10 1.64E+08

钍铀燃料物理 2012/11/2

The neutron spectra with different moderator(Water) size

After moderated,

Neutron Energy

spectra extend from

about 1MeV to thermal

neutron.

钍铀燃料物理 2012/11/2

In the region of 15 - 20MeV, no significant

difference between W and Ta target。

W and Ta is one of good candidates,

respectively

3 Neutron target selection

钍铀燃料物理 2012/11/2

The parameters of electron linac accelerator

Item working Region (1% TOF time resolution)

Thermal slow Fast

Electron energy 15 MeV 15 MeV 15 MeV

Pulse width 3 s- 0.5 us 30 ns-15 ns ~3 ns

Pulse frequency 10 Hz – 200 Hz 266 Hz 266 Hz

Average current 18 uA – 100 uA 2.5 uA-5 uA 0.5 uA

Average power 270 – 1500 W 37– 75 W 7.5 W

Neutron energy ~0.025 eV- 8 eV 8 eV-5 keV 5 keV- 60 keV

Diameter of e beam 3-4 cm 3-4 cm 3-4 cm

TOF of neutron 4m 3m 2m

Source strenght（ n/s） (0.72- 2.4)×1011 (0.2 - 2)×1010 2×109

Neutron flux (n/s/cm2) 104-105@4m 105@3m 103@2m

Time/Statistics error 1 day/ 1% 4 day/ 1% -5 % 7 day/ 1% -5 %

钍铀燃料物理

Element density

g/cm3

Melting point

/C

Young Modulus

/GPa

thermal

conductance

W/m/K

Tungsten-74(W) 19.3 3400 411 174

Tantalum-73(Ta) 16.5 2997 105 57.5

2012/11/2

From:

(1) The W has very high melting point and high Young Modulus,

(2) thermal conductance of W is three times higher then Ta, easy be cooled

So, we will choose the W as the target of photo–neutron source for 15 MeV electron Linac

钍铀燃料物理 2012/11/2

Thickness at 4 – 6 cm, the neutron yield approaches a saturated value

Diameter at 5 – 7 cm, the neutron yield approaches a saturated value

The W target size with 5 cm length and 6 cm diameter is selected

The design of W target

钍铀燃料物理 2012/11/2

Plate-shaped Target for high power beam

Selection of target model

Whole Target for low power beam

钍铀燃料物理 2012/11/2

7.5kW Power Target

Temperature

Reach Target

melting point

Max temperature

Cooling Water

Reach Boiling

point of Cooling

Water (1atm)

Cooling water speed 3m/s

Target : W ~1150C No ~70C No

Cooling water speed 3m/s

Target : Ta ~3300C Yes ~70C No

When water speed 3m/s，Ta target→not reach boiling point of Cooling water, but target

temperature reach the melting point (Melting point: W 3422 C, Ta 3017 C.)

When water speed 3m/s，W target→not reach boiling point of Cooling water, not reach

the melting point of W.

So the W target is a good choice at cooling water speed 3m/s，original temperature 25℃。

The W target can work on normal cooling condition

钍铀燃料物理 2012/11/2

Condition：electron 15 MeV，power 2 kW

Beam size 3σ=2cm(99.7% electron focus in diameter

4 cm

Simulation with purity W target + copper cooling base + Al

shell by ANSYS code

W target：φ6 cm x4.8 cm cylinder shape；

Copper base：thickness 4 cm；

Al Shell ：thickness 2 mm；

Inner Pipe：like heat sink, each rib length 8mm, thick

3mm, interval 2 mm。

Water Pipe: by diameter 3cm pipe。

Condition of cooling water：inlet water temperature 25C,

speed 1m/s，about 42.4L/min。

Outline of W target for 2kW Power

钍铀燃料物理

Results

2012/11/2 28

15MeV, 2kW electron＋W target model，at 25C;

Water speed at 1m/s（42.4L/min)，the temperature of water

and copper surface is 61C，

Temperature difference in entrance and exit water is less

then 1C .

So we can cooling W target safely at 2kW and 7.5kW 。

钍铀燃料物理

Layout of experimental setup of photo-neutron source @ SINAP

钍铀燃料物理 2012/11/2

eVEmL

t

t

t

E

E

sec02766.02

Neutron energy measured by TOF technique

4 Detection system

钍铀燃料物理 2012/11/2

TOF measurement：start signal

（1）record the recoil particle by neutron（6LiF/PE foil + recoil particle detector）；

（2）related particle：for example gamma ray with the neutron;

（3）pulse electron：RF signal from linac。

钍铀燃料物理

Neutron and Gamma ray detectors for primary measurement

钍铀燃料物理

Experimental plan Test and calibration for neutron source（First stage）。

Measure Flux of neutron and gamma rays.

Energy spectra of Neutron and Gamma。

Determine parameters of neutron source。

Calibration of detector, efficiency measurement。

Neutron data measurement（Second stage） Check Neutron source with Gold target, For example Au(n,tot), (n,)

Measure 232Th (n,tot), (n,γ) XS at resonant energy region

Measure 233U (n,tot), (n,γ) XS at resonant energy region

Measure neutron elastic scattering cross section

Other XS study

The main purpose of data measurement be focused on the total XS and capture reaction in 15MeV photon-

neutron source

钍铀燃料物理 2012/11/2 34

Experimental setup for（n, tot）reaction

Transmission method：measure neutron emitted at zero degree by neutron detector

Neutron detectors：

Liquid scintillator detector (thermal

and slow neutron)

6LiI: ZnS neutron detector（thermal

neutron）

钍铀燃料物理 2012/11/2 35

Experimental setup for （n, ）reaction

Liquid scintillator Detector

LiI／ZnS Detector

Detector（C6D6）

target

钍铀燃料物理

5 Summary

W target is the best choice for our first phase 15

MeV photo-neotron source.

We can cooling W target safely at 2kW and

7.5kW(max) beam power.

Main purpose of data measurement be focused

on the total cross section and capture reaction in

15MeV photon-neutron source

钍铀燃料物理 2012/11/2

Collabration Members：

Nuclear physics Division：WANG Hongwei，LI Chen，ZHANG Song，

ZHANG Guoqiang，CAO Xiguang，ZHONG Chen et al.,

And some master students。

Reactor Physics Division：CAI Xiangzhou，CHEN Jingeng，

WANG Naxiu，HUAN Jiangping，LIN Zuokang，HU Jifeng et al.,

Electron linac accelerator：GU Qiang，LIN GuoQiang et al.,

Reactor Safety Division：WANG Jianghua，CAI Junet al.,

Reactor Engineering Division：CAO Yun，HU Ruirong et al.,

Common office：HE zhanjun，FANG Guoping et al.,

Many thanks to our Consultant Prof ZHANG Guilin for useful discusstion.

Thanks for your helps

谢谢！Thinks

钍铀燃料物理 2012/11/2

Backup

钍铀燃料物理 2012/11/2

加速器束流脉冲对中子能谱测量的限制

0.025eV

脉冲频率是对测量能区最低能量限制

脉冲宽度是对测量能区最高能量限制。

15MeV 可以测量的中子能区

脉冲频率10-200Hz

脉冲宽度3us-0.5us

飞行路径4m

10%分辨区

脉冲频率266Hz

脉冲宽度30ns-15ns

飞行路径3m

脉冲频率266Hz

脉冲宽度3ns

飞行路径2m

钍铀燃料物理 2012/11/2 41

全套中子数据： 232,233,234Th、232,233,234Pa、232,233,234U

活化截面：233Pa (n,γ)234gPa、 233Pa (n,γ)234mPa、233Th(n, γ)

衰变数据：233,234Th、233,234,234mPa

233Th β-, T1/2=

22.3m, ENDSF

21.83m, Nucl.Wallet Card

中子反应截面测量—数据需求

几个关键问题及其对核数据的需求(Th-U燃料循环)

232Th/233U转化、235U的生成

钍铀燃料物理 2012/11/2

15MeV电子+W靶 0.5米/(n/s/cm2) 5米/(n/s/cm2)

中子 2kW/0.133mA 1.51E+07 1.43E+05

光子 2kW/0.133mA 1.81E+10 1.64E+08

电子能量15MeV，功率2kW/0.133mA，重复频率266Hz，90°方向：

钍铀燃料物理 2012/11/2 反应堆物理报告人 43

Th-U与U-Pu链比较

钍铀循环比铀钚循环在Z上

低2个“台阶”，从而决定了前

者在核能利用上相比后者有

一个先天性优越条件：后处

理较简单

tmsr physical design of photo-neutron source based on 15 ... · rpd 1 the requirement of ... study...

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