the use of the gdt based neutron source as driver in a sub-critical burner of minor actinides

Institute of Safety Research Member Institution of the Scientific Association Gottfried Wilhelm Leibniz

The use of the GDT based neutron source as driver in a sub-critical burner of minor actinides

K. Noack

Research Center Rossendorf (Germany)

Budker Institute of Nuclear Physics, September 26, 2006, Novosibirsk, Russia


Content

Part I: Transmutation of nuclear waste –

a short overview on the actual state

Part II: The GDT as neutron source in a

sub-critical system for transmutation?(~ Presentation at OS`2006, Tsukuba, Japan)


To become a long-term sustainable option for the worlds energy supply fission reactor technology must:

maximally use nuclear fuel (uranium) and

minimize its high level waste (HLW)!


: Partitioning & Transmutation

Main problem on long-time scale. HLW repository problem !

Goal: To transmute radio-isotopes in short-lived or stable isotopes by neutron reactions!

France, Japan, USA

UraniumU-235: 3-5%U-238: 95-97%

Burn-up Spent nuclear fuel

U: 95.5%

+ TRU isotopes• Pu: 0.9%• MA (Np, Am, Cm): 0.1%

+ Rad. FP isotopes: 0.4%

+ Stable isotopes: 3.2%

3-4 years

# In today´s Light Water Reactors (LWRs):

Problem on short-time scale.

1 LWR (~1.3 GWel.) produces per year (kg):

Pu: ~ 270 Am: ~ 13.5 Np: ~ 13 Cm: ~ 2FPs: ~ 1000


(B. Frois)

Classic glass

MA + FP

Pu + MA + FP

FPLight glass

# Radiotoxicity for various options of waste disposal:


From: M. Salvatores, FZR-presentation (2005)

FPs~3x102 years

Total

>105 yearsPu & decay products

~104 yearsMAs & decay products

Uranium ore

Tc-99, I-129

102 103 104 105 106

Years after discharge

R

adio

toxi

city


Geological Disposal

Direct Disposal

Spent Fuelfrom LWRs

# Partitioning & Transmutation of TRUs and FPs:From: M. Salvatores, FZR-presentation (2005)

Dedicated Fuel Fabrication

Pu MA

Partitioning & Transmutation (TRUs and FPs)

Partitioning

Transmutation

Geological Disposal

Dedicated Fuel

Reprocessing

FP

Pu, MA

FPPartitioning


# Neutron reactions for transmutation:

• Is the only option for FPs.

• However: secondary nuclei can be also long-lived.

• Thermal or intermediate (En: ~ eV-10 keV) neutrons are necessary.

• Minor actinides are fissionable!

• Fission is the preferable reaction for transmuting MAs : - substantially shorter life-times,

- possibility of „fast systems”.

• „Fast“ neutrons with En > 0.5 MeV are necessary.

Capture Fission

• : „Fast systems” should be a suitable tool for transmuting MAs!

• : Only low transmutation rates of FPs achievable!M. Salvatores: The problem is not yet solved!


• A „fast system“ with high neutron flux inside an acceptable large volume!

Fission Technology offers two options:

# An efficient burning of Pu and MA isotopes demands:

„Driven sub-critical system“ „Fast reactor“

– Main class: ADS = Accelerator Driven System

: What is the most important physical difference ?

&

What is the advantage of an ADS compared to FR ?


# Neutron field in a reactor:

Solution of the Static Reactor Equation = eigenvalue equation

• Neutron field power distribution in the reactor

• Eigenvalue = keff - “effective multiplication factor”

> 1 - super-critical reactor, P:

keff = 1 - critical reactor, P:

< 1 - sub-critical reactor P:

A minimum on fission reactor physics:

Important phenomenon:

„Delayed“ fission neutrons with a relative portion: eff6.5x10-

3 !

It makes possible to control a fission reactor !


1.0

0.99

0.98

„delayed“ super-critical state

1)(kTwitheP(t)

eff

T

t

„prompt“ super-critical state

critical state constant power

1+eff1.0065

eff

super-critical state

sub-critical state

keff 3effeffeff

-4-5pr.

10β1kk

s;1010

: T 0.01 - 0.1 s !!!

3eff

del.45

pr.

101k

s0.1s10 s,1010

: T 100 s !

„driven sub-critical systems“~0.95

?10-3 What is the impact of a

power increase on keff ?

(“reactivity effects”)


• Fast reactors:

- eff should be large!

- Positive total reactivity effects (keff ↗) should not appear!

: What is the impact of MAs on these demands?

Reactor safety considerations:

• Driven sub-critical systems: keff ≤ 0.98 !

: „They offer much higher flexibility for burning Pu and MAs than Fast Reactors“ !

In Fast Reactors the maximum allowable fraction of MAs in the fuel is ~ 5 % only !


2030 2040 2050 2060 Time

Waste

Strategic role of Driven Sub-critical Sytems in the future of Nuclear (Fission) Energy in US

: The use of the GDT neutron source as driver in a Driven System for transmutation of nuclear waste could be an additional goal for further Research & Development !

M. Cappiello, „The potential role of Accelerator Driven Systems in the US“, ICRS-10 (2004)

Use of ADS


- 50

- 40

- 30

- 20

- 10

0

10

20

2 0 4 6 8 10

A

D D

C

C

B

Act. Mineurs Chargés (%)

Variation (%)

B

A: Na-void effect (keff ↗)

B: Doppler-effect (keff↘)C: Burn-upD: eff

Increase of Na-void effect !

Decrease of eff !

Decrease of Doppler effect !

# Effect of MA introduction on reactivity coefficients in a Na-cooled Fast Reactor:

Bad effects by MAs:

Decrease of burn-upGood effect:

From: M. Salvatores, FZR-presentation (2005)


THE GDT AS NEUTRON SOURCE IN A

SUB-CRITICAL SYSTEM FOR TRANSMUTATION?

K. Noack

Research Center Rossendorf (Germany)

A. Rogov

Joint Institute of Nuclear Research Dubna (Russia)

A.A. Ivanov, E.P. Kruglyakov

Budker Institute of Nuclear Physics Novosibirsk (Russia)

Open Systems´2006, July 17-21, 2006, Tsukuba, Japan

(With modifications for BINP-presentation)


2

Fission reactor technology must recycle spent nuclear fuel and minimize its high level waste (HLW) !

Introduction (1/3)

: Partitioning & Transmutation !

Main problem on long time scale. HLW repository problem !

Goal: To transmutate radio-isotopes in short-lived or stable isotopes by neutron reactions.

Japan (JAEA): „OMEGA“

UraniumU-235: 3-5%U-238: 95-97%

Burn-up Spent nuclear fuel

U: 95.5%

+ TRU isotopes• Pu: 0.9%• MA (Np, Am, Cm): 0.1%

+ Rad. FP isotopes: 0.4%

+ Stable isotopes: 3.2%

3-4 years


(B. Frois)

Classic glass

MA + FP

Pu + MA + FP

FPLight glass


Introduction (2/3) 3

Two efficient ways for transmutation of TRU´s by

neutron reactions:1) Fast reactors (“effective multiplication factor”: keff=1)

2) Sub-critical systems (keff=0.95-0.98) that are driven by an “outer” neutron source

• Advantage: More flexibility because of less stringent safety requirements !

• Requirement: Powerful neutron source !

– „Accelerator Driven Systems“ (ADS)

- Spallation neutron source„ADS“

# Suitability of the GDT n-source for a driven system?

# How does it compare with the ADS?

:


Introduction (3/3) 4

The idea of a GDT-DS for transmutation:

GDT experimental device (BINP, Novosibirsk)


ADS GDT (“basic variant”)

The Neutron Sources 5

Comparison of near-term projects:

2) Energetic efficiencies PAccel. = 20 MWel PNBI = 60 MWel (!)

price [W/(n/s)]: pADS = 1.6x10-11 pGDT = 8.7x10-11 (!)

# Peculiarity of the GDT-source: SGDT = 2 x (1/2) !

1) Total intensities

p-beam: 1 GeV x 10 mA = 10 MW

Yn = 20 n/p (at Pb)

: SADS = 12.5x1017 n/s

n-power: Pn=1.56 MWDT fusion neutrons

SGDT=6.9x1017 n/s

Factor ~ 1.8

Factor ~ 5 !

# SNS (ORNL): 1 GeV x 1.4 mA, 60 Hz pulsed, 28.04.2006 – first neutrons !

Pn0.25 MW


# Spallation reaction: neutron yield per proton (Pb, Pb/Bi): K. van der Meer et al., Nucl. Instr. and Meth. in Phys. Res. B 217 (2004) 202-220


(From Yu. Tsidulko)

: Pn=

: Pinp= (el. Power)

Power losses

should be

reduced or

recovered!


# Features

Calculation Models (1/2) 6

p

Core

Reflector

200

150

120

100 20 14292

50

0

Hei

ght

z (c

m)

Tar

get

Bu

ffer

Voi

d

Radius r (cm)

# OECD-NEA CalculationBenchmark (1999) for anaccelerator-driven MA-burner with nominal power = 377 MW.(Developed from ALMR/PRISM)

# ADS principles

• Dedicated core: Pu & MA Fe, Pb-Bi • Coolant: Pb-Bi eutectic• Reflector: Steel, Pb-Bi• Target: Pb-Bi• Buffer: Pb-Bi

32% , 68%!!!


Cz

r

Bz

r

Calculation Models (2/2) 7

A

# Geometric systems:

„ADS“ „GDT-DS“ „GDT-DS+B“

# “External” neutron sources:

Spallation spectrum in „GDT-DS“„MIXED“

z

r

Spallation source

DT fusion source – cylinder:Radius: 10 cm

Height: 50 cm


Neutron Transport Calculations (1/5) 8

• Neutron transport code: MCNP-4C2

• Nuclear data from: JENDL-3.3 (NDC of JAEA)

Tools:

Two types of transport calculations:

• Reactor criticality calculation (without external source) keff

• With external sources



Geometry system

´Reactor´ Driven Systems

keff Meff MS hfis / MeV rn,2n

A 0.95856 23.1 ADS 21.5 1316 0.088

B 0.95008 19.0GDT-DS 34.7 2119 1.20

C 0.95817 22.9 GDT-DS+B 44.4 2710 1.73

Calculated integral parameters (per source neutron):

Spall. Sp. 17.5 1070 0.065

Effective multiplicity: Meff=keff/(1-keff)

# Positive feature of 14 MeV neutrons:High probability of n,2n reactions at Pb and Bi !But: No effect at Na !

# 0.95 < keff < 0.96 ! (1999)Bz

r


total

n,2n

n,3nn,

10 MeV



Flux distributions (per source neutron):

0.E+00

2.E-03

4.E-03

6.E-03

8.E-03

20 30 40 50 60 70 80 90 100

Radius (cm)

Flu

x (n

/(s

cm2 ))

ADS GDT-DS GDT-DS+B ´Reactor´

Total Flux: Radial dependence in core




0

1

2

3

50 100 150Height z (cm)

Pow

er p

eak

fact

or

ADS GDT-DS+B ´Reactor´

Power peak factor over height at r=21 cm




0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1.E-05 1.E-04 1.E-03 1.E-02 1.E-01 1.E+00 1.E+01 1.E+02

Energy (MeV)

Gro

up fl

ux (n

orm

aliz

ed)

ADS GDT-DS GDT-DS+B ´Reactor´

Spectra of energy group fluxes at r=21 cm


The MA-burners (1/2) 13

Calculated integral parameters:

Parameter ADS GDT-DS/2* GDT-DS+B/2*

S (1017 n/s) 12.5 3.45 3.45

Pfis (MW) 263 117 150

Nominal Power

377 MW:

1) S´ (1017 n/s) 17.9 11.1 8.67

2) k´eff 0.9707 0.9840 0.9829

* One MA-burner on each side !

x ~1.5!

Today: 0.96 < keff < 0.98 !

0.95817

Q=5.2 Q=2

efffis MSP

0.950080.95856keff:

! 2.5~ x


The MA-burners (2/2) 14

2.0E+124.0E+126.0E+128.0E+121.0E+131.2E+131.4E+131.6E+132030405060708090100Radius (cm)Flux (n/cm2 /s) ADSGDT-DSGDT-DS+B/2Reactor

2.0E+12

4.0E+12

6.0E+12

8.0E+12

1.0E+13

1.2E+13

1.4E+13

1.6E+13

20 30 40 50 60 70 80 90 100

Radius (cm)

Flux

(n/

cm2 /s

)

ADS GDT-DS/2 GDT-DS+B/2 ´Reactor´

Radial flux distribution (at nominal power):


Tritium breeding 14a

T-breedingmodule

# T-breeding module:– ITER inboard module,

– He cooled pebble bed(Be and breeder pebble beds,breeder: Li4SiO4 with 40% Li-6)

– FZKA 6763 (FZ Karlsruhe, 2003)

– 6Li + n 4He + 3H + 4.8 MeV

Result:

355.3 g tritium / f.p. year !

(„basic variant“, sum of both sides)


Conclusions (1/2) 15

(1) Energetic price of the neutron emission intensities: pGDT 5 x pADS !!!

(2) ADS and GDT neutron source projects do not supply sufficiently high source intensities to operate the MA- burner at nominal power. For that are necessary:

SADS: x ~1.5 SGDT: x ~2.5 (for 2 burners !)

(3) Alternatively, one has to redesign the MA-burner so that for ADS: keff 0.97 for GDT: keff 0.98. !!!

(4) Fusion source neutrons generate a substantially higher fission power in the core by n,2n reactions at the nuclei of the Pb-Bi coolant!


Conclusions (2/2) 16

(5) The power multiplication factor Q of the driven MA-burners:

QADS 2.6 x QGDT-DS !

(6) For the same power of the driven MA-burners one can expect:

[MA-burning rate]ADS [MA-burning rate]GDT-DS


1) Energetic efficiency must be increased!

# The Q-factor must be comparable with that of ADS!

# Increase of Te is the key issue:

Te = 0.75 keV Te 2.25 keV !

inp

effe

inp

fis

P

M)S(T

P

PQ

2) „Next Step“ with a modified MA-burner: Project „π“

# MA-burner*: k*eff=0.98, P*th=500 MW

GDT-NS*: S*=10.8x1017 n/s (P*n=2.5 MW)

instead of: S= 6.9x1017 n/s (Pn=1.56 MW)

by: Te=0.75 keV T*e1.25 keV !

As goal for the GDT neutron source project:

~60%


# Pinj=60 MW (el.), Einj=65 keV

2

0.75

„Basic variant“ + 2 burners=

~1.25

3.142 x 500-MW-burners*, k*eff=0.98

Q

5.2

~2.25

2 x 377-MW-burners

Diagram from Yu. Tsidulko


Thank you!


1) Source strength (neutron power):

# MA-burner: keff=0.98, Pth=500 MW

GDT-NS: S=10.8x1017 n/s (Pn=2.5 MW)

instead of: S= 6.9x1017 n/s (Pn=1.56 MW)

As goal for the GDT neutron source project:

2) Energetic efficiency:

# The Q-factor must be comparable with that of ADS!

# Increase of the electron temperature is the key issue:

Te=0.75 keV Te=2.25 keV !

~60%


# Transmutation of 99Tc using neutron capture:R. Klapisch, Europhysics News, Vol. 31 No. 6 (2000); (Proposed by C. Rubbia)

„Adiabatic resonancecrossing“


# Flux spectra of the MA-burner and of FR PHENIX:

[104<--------->4x106]

Fast Neutronspectrum

(Na cooled)

From: G. Alberti et al., NSE 146, 13-50 (2004)

„Fast systems“


: At high neutron energies (En>0.5 MeV) fission dominates over capture !

FR

FR

FR

FR

# σc and σfis for important TRUs:

E (eV) 104 105 106 107

From: D. Westlen, RIT Stockholm (2001)


α – probability of capture

# Advantage of fast neutron spectra for MA-burning:Originally from C. Rubbia


„Energy amplifier“ proposed by C. Rubbia (1993):

• Accelerator ↓particle beam↓

• Target↓neutrons↓

• Sub-critical system (arrangement of nuclear fuel)

↓Strong neutron field inside the

whole volume of the fuel systemby means of fissions !

Release ofnuclear energy

Transmutation of nuclear waste !

(protons)

(heavy metal)(spallation)

# Principles of an ADS:


# Schematic view of a lead-cooled Fast Reactor (pool-type):

• Core without external neutron source

• Power control by absorber rods

• Is one of 3 Fast Reactors among 6 reactor types

considered in the GENERATION IV -

International - Forum.

the use of the gdt based neutron source as driver in a sub-critical burner of minor actinides

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