eaqu

The ecological problems of
the Earth and role of
Physics in their solution.
Lecture 14.
The modern technologies
on protection environment
(C) Arjannikov A. V.
Radiational purification of
water from chemical pollution
The scheme of the water purification
factory from industrial discharges
Electron beam irradiation of aqueous
solutions
H 2O
e
H 3O ; OH
OH ; eaqu ; H
H 2 ; O 2 ; H 2O 2
O3 +
eaqu
H
H 2O 2
OH
Radiation is absorbed by the water not by solutes !
Two sources for OH (water radiolysis and O3
decomposition)
Radiolysis of Water Molecule
Radiolysis of Water
The constants of interaction radical ОН with
different componentry
The efficiency of work of the radiational
installation increases in addition of ozone
The scheme of installation for radiational
destruction of detrimental water pollutants
Electron beam treatment
All compounds degraded - most 95% or more without
optimization; Even perchlorate (50%reduction);
Evidence of competition;
Some faster than others predictable; Can be leveraged
Radiational purification of
water from bacteriological
pollution
Radiational disinfection of water
EFFECT OF
WATER THICKNESS
ON
ELECTRON
DISINFECTION
OF
WASTEWATER
(secondary effluent)
(Miyata et al., 1990)
2 MeV electrons
c0 = 2.5 x 104
cells/ml
The efficacy of a destruction of unhealthy
microorganisms using radiation exposure.
Inactivation of different microorganisms
in a secondary effluent by electron
beam irradiation
Reduction of different estranes in a
secondary effluent by gamma
irradiation
The comparison of different methods of
a disinfection
Disinfection mechanisms by E-beam
Electron beam irradiation system
Penetration Depth of γ-ray and ebeam.
Different types of reactors for radiation
purification of water
Outside view of working area of plant
with stream of water.
The simplest drawing of building for
accelerator
Low level of radiation outside
is provided by concrete walls
and roof
The entrance of irradiation
room is equipped by moving
steel door of labyrinth. The
labyrinth should provide
passing of radiation through 3
reflection as minimum
Composition of accelerating plant for
water treatment
Explicit costs for disinfectant plants with different
methods of destruction of microorganism.
Neutron afterburning of the
radioactive wastes
In today´s Light Water Reactors (LWRs):
Uranium
Burn-up
U-235: 3-5%
U-238: 95-97%
3-4 years
Main problem
on long-time
scale.)
1 LWR
(~1.3 GW
el.
Æ HLW repository problem !
produces per year (kg):
Problem on short-time
Pu:scale.
~ 270
Am: ~ 13.5
Æ: Partitioning
Np: ~ 13
& France, Japan,
Cm: USA
~2
Transmutation
FPs: ~ 1000
Spent nuclear fuel
U:
+ TRU isotopes
• Pu:
• MA
(Np, Am, Cm):
95.5%
0.9%
0.1%
+ Rad. FP isotopes: 0.4%
+ Stable isotopes:
3.2%
Goal: To transmute radio-isotopes in short-lived
or stable isotopes by neutron reactions!
1 LWR (~1.3 GWel.)
produces per year (kg):
Pu: ~ 270
Am: ~ 13.5
Np: ~ 13
France, Cm:
Japan, USA
~2
FPs: ~ 1000
Radiotoxicity for various options of waste
disposal:
Radiotoxicity
MAs & decay products
~104 years
FPs
~3x102 years
Pu & decay products
>105 years
Uranium ore
Tc-99, I-129
102
103
104
Years after discharge
105
106
From: M. Salvatores, FZR-presentation (2005)
Partitioning & Transmutation of TRUs
and FPs:
Geological Disposal
Direct Disposal
Partitioning & Transmutation (TRUs and FPs)
Partitioning
Spent Fuel
from LWRs
Pu MA
Dedicated Fuel
Fabrication
Geological Disposal
FP
Transmutation
FP
Partitioning
Dedicated
Fuel
Reprocessing
Pu, MA
From: M. Salvatores, FZR-presentation (2005)
Neutron reactions for
transmutation:
Capture
Fission
• Is the only option for FPs.
• Minor actinides are fissionable!
• However: secondary nuclei
can be also long-lived.
• Fission is the preferable reaction for
transmuting MAs
Æ: - substantially shorter life-times,
- possibility of „fast systems”.
• Thermal or intermediate
(En: ~ eV-10 keV) neutrons
are necessary.
• Î: Only low transmutation
rates of FPs achievable!
M. Salvatores:
The problem is not yet solved!
• „Fast“ neutrons with En > 0.5 MeV
are necessary.
• Î: „Fast systems” should be a
suitable tool for transmuting MAs!
An efficient burning of Pu and MA isotopes demands:
• A „fast system“ with high neutron flux
inside an acceptable large volume!
Fission Technology offers two options:
„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 ?
A minimum on fission reactor physics:
# Neutron field in a reactor:
Solution of the Static Reactor Equation = eigenvalue
equation
• Neutron field Æ 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:
™ Important phenomenon:
„Delayed“ fission neutrons with a relative portion: βeff≅6.5x10-3 !
Î It makes possible to control a fission reactor !
keff
τ → τ pr. ≅ 10 -5 − 10 -4 s;
>>> k eff → k eff = 1 + βeff + 10 −3 Î: T ≅ 0.01 - 0.1 s !!!
1+βeff≅1.0065
βeff
1.0
10-3
?
„prompt“ super-critical state
τ pr. ≅ 10 −5 − 10 −4 s, τ del. ≅ 10 s → τ ≅ 0.1 s
super-critical
state
−3
Î: T ≅ 100 s !
>>> k eff = 1 + 10
„delayed“
What
is the super-critical
impact of a state
critical
state Æon
constant
power
increase
keff ? power
t
(“reactivity effects”)
P(t) ∝ e with T =
T
0.99
sub-critical state
τ
(keff − 1)
0.98
~0.95
„driven sub-critical systems“
Reactor safety considerations:
• Fast reactors:
- βeff should be large!
- Positive total reactivity effects (keff
appear!
) should not
Î: What is the impact of MAs on these demands?
™ In Fast Reactors the maximum allowable fraction of
MAs in the fuel is ~ 5 % only !
• Driven sub-critical systems:
keff ≤ 0.98 !
Î: „They offer much higher flexibility for burning Pu and
MAs than Fast Reactors“ !
Strategic role of Driven Sub-critical Sytems in the
future of Nuclear (Fission) Energy in US
M. Cappiello, „The potential role of Accelerator Driven Systems in the US“, ICRS-10 (2004)
Waste
Use of ADS
2030
2040
2050
2060
Time
Î: 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 !
Introduction (1/3)
2
¾ Fission reactor technology must
ƒ recycle spent nuclear fuel and
ƒ minimize its high level waste (HLW) !
Uranium
Burn-up
U-235: 3-5%
U-238: 95-97%
3-4 years
Main problem on long time scale.
Æ HLW repository problem !
Æ:
Partitioning
& Japan (JAEA): „OMEGA“
Transmutation !
Spent nuclear fuel
U:
+ TRU isotopes
• Pu:
• MA
(Np, Am, Cm):
95.5%
0.9%
0.1%
+ Rad. FP isotopes: 0.4%
+ Stable isotopes:
3.2%
Goal: To transmutate radio-isotopes in short-lived
or stable isotopes by neutron reactions.
Partitioning and reprocessing
Introduction (2/3)
¾ 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)
„ADS“
- Spallation neutron source
: # Suitability of the GDT n-source for a driven system?
# How does it compare with the ADS?
3
Introduction (3/3)
The idea of a GDT-DS for transmutation:
GDT experimental device (BINP, Novosibirsk)
4
The Neutron Sources
¾ Comparison of near-term projects:
ADS
5
GDT
(“basic variant”)
1) Total intensities
Pn≅0.25 MW
Î:
• n-power: Pn=1.56 MW
• p-beam:
DT fusion neutrons
1 GeV x 10 mA = 10 MW
# •SNS
Yn =(ORNL):
20 n/p (at Pb)
1 GeV x 1.4 mA, 60 Hz pulsed,
17 n/s
17
•28.04.2006
SADS = 12.5x10
– first neutrons
! • SGDT=6.9x10 n/s
2) Energetic efficiencies
• PAccel. = 20 MWel
Factor ~ 1.8
• PNBI = 60 MWel (!)
-11
-11
Î price [W/(n/s)]: • pADS = 1.6x10
Factor ~ 5 ! • pGDT = 8.7x10 (!)
# Peculiarity of the GDT-source:
• SGDT = 2 x (1/2) !
As goal for the GDT neutron source
project:
1) Source strength (neutron power):
# MA-burner:
keff=0.98,
Pth=500 MW
Î GDT-NS:
instead of:
S=10.8x1017 n/s (Pn=2.5 MW)
S= 6.9x1017 n/s (Pn=1.56 MW)
~60%
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
Æ
Te=2.25 keV !
Transmutation of 99Tc using neutron
capture:
R. Klapisch, Europhysics News, Vol. 31 No. 6 (2000); (Proposed by C. Rubbia)
„Adiabatic resonance
crossing“
From: G. Alberti et al., NSE 146, 13-50 (2004)
Flux spectra of the MA-burner and of FR PHENIX:
„Fast systems“
(Na cooled)
Fast Neutron
spectrum
[104<--------->4x106]
σc and σfis for important TRUs:
From: D. Westlen, RIT Stockholm (2001)
FR
FR
E (eV) 104 105 106 107
FR
FR
Æ: At high neutron energies (En>0.5 MeV) fission dominates
over capture !
Originally from C. Rubbia
Advantage of fast neutron spectra for
MA-burning:
α – probability
of capture
„Energy amplifier“ proposed by C. Rubbia (1993):
Principles of an ADS:
• Accelerator
↓
particle beam
↓
• Target
↓
neutrons
↓
(protons)
(heavy metal)
(spallation)
• Sub-critical system
(arrangement of nuclear fuel)
↓
Æ Strong neutron field inside the
whole volume of the fuel system
by means of fissions !
Release of
nuclear energy
Transmutation of
nuclear waste !
Schematic view of a leadcooled Fast Reactor
(pool-type):
• Is one of 3 Fast Reactors
among 6 reactor types
considered in the
GENERATION IV International - Forum.
• Core without external
neutron source
• Power control by absorber
rods