Transcript Kamash Waste from Nuclear Power Plants

Management of Radioactive
Waste from NPP
Prof. Dr. A.M. El- Kamash
Hot Lab.& Waste Management Center
AEAE
[email protected]
Content
•
•
•
•
•
Introduction
Power reactor wastes
Fuel cycle wastes
Treatment of Radioactive waste, and
Waste management practice in Egypt
Introduction
• At the end of the 20th century, nuclear
energy supplied about 16% of the world
electricity needs
• The growth of the nuclear industry in
different countries has been the natural
consequence of an increasing need for
electrical power.
Introduction
• The future prospects of nuclear power are
related to the following issues:
1) Public confidence, or at least tolerance, particularly on an
accepted solution to the disposal of high level waste.
2) The competitiveness in terms of capital costs and construction
periods.
3) Identification of appropriate linkages between nuclear power
and environmental issues, such as global climate change, local
air quality and regional rain acidification.
4) Lastly, the need for a global approach to some activities of
nuclear power, such as nuclear waste management.
These issues are related to the country’s energy policy and
international co-operation and therefore belong to the
governmental domain of competence.
Introduction
Radioactive waste generated from NPP can be
divided into
– power reactor wastes, and
– fuel cycle facility wastes,
•Power reactors are responsible for the largest
volume of LLW.
•Fuel cycle plants, such as fuel enrichment plants
and fuel fabrication plants, produce small volumes of
LLW relative to power reactors.
Power Reactor Wastes
• Component of NPP
• Nuclear Power plant.exe
Power Reactor Wastes
The majority of power reactor wastes are
classified as:
1)
2)
3)
4)
5)
Liquid radioactive wastes,
Wet solids (including slurries),
Dry active solid wastes (DAW),
Liquid organic wastes, and
Thermal waste.
Power Reactor Wastes
Power Reactor Wastes
1) Liquid Radioactive Wastes
• Liquid radioactive wastes are produced from
recycled reactor core fluids, hydraulic fluid from
equipment repairs, housekeeping activities, and
laundering.
• These wastes are treated to remove the maximum
amount of radioactive contamination.
• Treated liquids are then typically recycled or
discharged to the environment under the control
of the plant operating license and national
regulations.
Power Reactor Wastes
2) Wet solids
Radioactive wet solid wastes consist of solid
wastes containing greater than 5% liquid.
Most radioactive wet solid wastes are
produced from cleaning aqueous
processing systems at power reactors.
• Spent Ion-Exchange Resins
• Filter Sludge
• Cartridge Filters
Power Reactor Wastes
3) Dry active solid wastes
•
•
•
•
Anticontaminant clothing
Cloth (rags, mops, gloves)
Contaminated dirt
Contaminated tools and
equipment, Filters
• Glass
• High density concrete block
• Miscellaneous metal, Aerosol
cans, Buckets, Crushed drums,
Fittings, Pipes and Valves
• Miscellaneous wood
• Plastic
• Bags, gloves, shoe covers,
Sample bottles
• Rubber,
• Sweeping Compounds
• Irradiated metal alloys
• Flux wires, Flow channels,
Fuel channels, In-core
instrumentation, Poison
channels, Shim rods.
Power Reactor Wastes
4) Liquid organic wastes
• liquid organic wastes includes pump oil,
lubricating oils, organic resins, liquid
scintillation counting solutions, and
decontamination solutions containing organic
chelating agents.
• Liquid organic waste volumes are very small
when compared to the total generated volume
of LLW
Power Reactor Wastes
5) Thermal waste
• This waste is common both to conventional and
nuclear plants.
• The quantity of thermal waste proportional to
the size of the plant.
• In a NPP with a PWR operates at a thermal
power of 1000 MW must dispose of
approximately 2.4 million Btu/s. If this quantity
of heat were released into a river having a flow
rate of 1000 cubic ft/s, the entire river
temperature would rise by 33 degrees
Fahrenheit.
Fuel Cycle Wastes
Fuel cycle facility wastes include
• Calcium fluoride generated from hydrogen
fluoride gas scrubbers,
• Filter sludge,
• Contaminated equipment, and
• Trash.
Fuel Cycle Wastes
Objective of RWM
• To collect, handle, treat, condition, store,
transport, and dispose RW in a manner that
protects the human and the environment
without imposing undue burden on future
generation.
Principles of RWM
•
•
•
•
•
Establishing a national legal framework,
Control of radioactive waste generation,
Safety of facilities,
Waste generator pays,
Sound decision-making based on scientific
information,
• Risk analysis and optimization of resources,
• International cooperation
Requirements of National
RWM System
• Organizational structure
• Safety requirements and conditions
– International recommendations, standards and agreements
– National legislation
•
•
•
•
•
•
•
Cost and funding
Technical capability of personnel
Public involvement and political acceptance
Other non-technical factors
Geographic conditions
Opportunity for international co-operation
Physical infrastructure
Activities in RWM System
Generation
Characterization
Pre-treatment
Treatment
Discharge
Conditioning
WAC
Transportation
Disposal
S.A.
Treatment Technology
Treatment technologies of LLW and MLLW
range from the very simple to extremely
complex. These technologies could be divided
into eleven broad categories as follows:
 Sizing
 Compaction
 Filtration
 Decontamination
 Evaporation
 Separation
 Incineration
 Vitrification
 Metal Recovery

Immobilization/Stabilization
 Physical/Chemical Treatments.
Treatment of RW
1) Treatment of aqueous wastes.
2) Treatment of solid wastes.
Characterization of Liquid Waste
• Liquid wastes are generally characterized by their
chemical, physical, radiological and their biological
properties.
• Chemical properties: toxicity, chemical composition of the
liquid, pH value, oxygen demand, and Zeta potential.
• Physical properties: turbidity, density, viscosity, surface
tension., conductivity, emulsifying ability
• The radiological: affect the choice of the treatment process
and and the radiological impact to operators and the
surrounding environment.
Selection of Treatment System
Selection of a liquid waste treatment system
involves a set of decisions related to the following
factors.
•Characterization of arising waste,
•Discharge requirements for decontaminated liquors,
•Available technologies and their costs,
•Conditioning of the concentrates, and
•Storage and disposal of conditioned concentrates
Treatment Processes
Selection of a process for liquid wastes treatment
depends on the radiological and physico-chemical
properties and the quantity of arising waste.
The processes commonly used for treatment of
liquid radioactive wastes fall generally into three
main categories:
• Chemical precipitation,
• Ion exchange, and
• Evaporation.
Ion Exchange
Ion exchangers are insoluble solid materials which
carry exchangeable ions. These ions can be
exchanged by a stoichiometrically equivalent
amount of other ions of the same sign when the
ion exchanger is in contact with an electrolyte
solution.
Ion exchangers are generally classified according to
their exchange function:
• Cation Exchangers,
• Anion Exchangers
• Amphoteric Ion Exchangers
Advantages of Ion Exchange
• Treatment procedures are based on well proven,
conventional process and equipment,
• Suitable for ionic impurities,
• High quality effluents are possible,
• Adequate for separation of several radionuclides
• High decontamination factor achievable giving low
volumes of solid waste which can be readily conditioned
for disposal,
• Suitable for separation of colloids, and
• Suitable for continuous and automatic operation.
Disadvantages of Ion Exchange
•Salt content and suspended solids must be low,
•Non electrolytes are not exchanged, colloids, and
contaminants can cause difficulties,
•Some exchangers are pH-sensitive,
•Regeneration give rise to secondary wastes,
•Some exchangers have low radiation tolerance, especially
organic materials
•Some exchangers (e.g. organic) are expensive,
•Some exchangers have limited stability to heat
Evaporation
• Types of Evaporators
• Dot kettle. natural forced circulation, vaiour
cothpression and wiped-filin evaporators.
• Evaporators which can operate in the presence of
solids appear to be the most suitable for the
treatment of bearing waste streams, since actinide
hydrolysis products are mainly associated with
suspended particulates and colloidal materials in
feeds that are weakly acidic or neutral.
Advantages of Evaporation
• Large volume reduction for a range of effluents,
• Good
decontamination
from
non-volatile
radionuclides,
• Complete removal of all active and inactive salts
from waste effluent allowing reuse of condensates
and avoiding the problems caused by the build-up
of inactive salts.
• Unaffected by the presence of complex agents in
waste effluents, unlike many of the alternative
treatment processes
Limitations of Evaporation
• Unsuitable for waste effluents containing large salt
concentrations,
• Expensive compared to other treatment processes
due to the high energy needs.
• The problems caused by corrosion, scaling and
foam formation may prevent the successful
application,
The presence of some organics can result in
explosions on evaporation and appropriate
pretreatment is required, such as steam stripping.
Discharge Requirements for
Decontaminated Liquors
• Restrictions or limits on release of the decontaminated
liquors should be carefully considered.
Determination of these limits is done differently in various
countries but does in all cases, require extensive analyses
by both the waste producer and regulating authority to
arrive at an agreement that the releases are acceptable.
Conditioning of Sludge, Concentrates
and Ion Exchangers
• Two methods have been used: cementation and
bitumization.
• For each matrix material, several techniques could be used
in view of how the wastes are mixed with the matrix
material.
• Normally, immobilization is carried out in fixed
installations at the site of waste generation, but also mobile
systems have been developed for some applications
The management strategy for solid waste of
small nuclear research centers in developing
countries.
Main features of the solid waste treatment
processes.
Treatment Technology
Compaction
A well proven volume reduction technology used to reduce
the total volume of waste. This is accomplished by
applying high pressures to the waste, which reduces
void space.
Compactor systems consist of a press, using horizontal or
vertical rams to apply pressure to the waste in a drum
or box-type container. Volume reduction achieved
during compaction is a function of
• Void space in the waste,
• The force applied by the press, and
• The bulk density of the material.
Treatment Technology
Compaction
Advantages of compaction include
1) Compaction is a proven process used
throughout the world in the nuclear industry,
2) Compaction systems are simple, and tend to
be reliable and trouble free,
3) Waste compaction is relatively inexpensive,
and
4) The process is simple to operate.
Treatment Technology
Compaction
Disadvantages of compaction include
1) Most commercial compactor systems are not available
with adequate exhaust equipment and must be
modified,
2) Compactors cannot reduce the hazard of the
incoming waste, and are therefore not appropriate for
treating waste streams with hazardous constituents,
3) Compaction is not recommended for wastes
containing free liquids, or with wastes containing
explosives, and
4) Compaction should not be used on dense or bulky
items where minimum volume reduction would be
An in-drum compactor
IMMOBILIZATION
MATERIALS AND PROCESSES
Benefits of Solidification
► Prevent dispersion of fines and
liquids during handling
► Minimize releases of radionuclides
and hazardous constituents after
disposal
► Reduce potential exposure to
intruders, long term solution
Desirable properties of a
solidification agent
► Availability
► Low cost
► Volumetric efficiency
► Simplicity of use
► Good waste form properties
Important properties of
solidified waste forms
► Low leachability
► High chemical stability
► High compressive strength
► High radiation resistance
► High resistance to biodegradation
► High thermal stability
► Low solubility
Solidification agents
currently in use
► Cement, with and without additives
► Blended Cements (Fly ash, slags, etc.)
► Bitumen
► Glass or ceramics
►Polymers
Pictorial flow sheet of liquid waste
processing
Conditioning of compatible radioactive solid
wastes by in-drum compaction
Conditioning of non-compatible radioactive solid waste
Advantages and disadvantages of cement
Advantages
Disadvantages
● Technology and materials
● Some wastes affect
are well known and available
setting
● Compatible with
● Swelling and
many wastes
cracking may occur
● Volume increase and
● Low cost
high density for
● Good impact and
shipping and disposal
compressive
strength
STORAGE
Typical stacking of waste drums
OVERVIEW ON THE
TREATMENT OF RADIOACTIVE
WASTE IN EGYPT
The liquid radioactive
waste Treatment Facility
The facility treats:
3
- 10 m per day of LLW
- 2 m3 per day of ILW
- Average activity:
37- 3700 KBq/L
Material flow diagram of the liquid radioactive
treatment facility at Inshas Site
1- Low level waste processing :
* Reception and averaging;
* Coagulation;
* Settling;
* Clarifying; and
* Demineralization by ion exchange
2- Intermediate level waste
processing :
* Reception, averaging and pH-conditions;
* Evaporation;
* Secondary steam condensation;
* Concentrate collection; and
* Immobilization by cementation
IN-LINE CEMENTATION UNIT
At Inshas Site
- Put into operation for one to two shifts per
week
- Treats about 3 m3 of solid wastes
(concentrates) per shift
- Volume of cement in the hopper is 8 m3
Simplified flow diagram for the in-drum
cementation unit
SOME PHOTOS OF THE LIQUID
RADIOACTIVE TREATMENT FACILITY AT
INSHAS SITE
CONTAINER OF RADIOACTIVE WASTES
(2.0 m3)
ION EXCHANGE COLUMNS
BIOLER FOR ILW
LINE FOR EVAPORATOR CONCENTRATES AND
SLUDGES TO THE CEMENTATION PLANT
OVERVIEW OF CEMENTATION PLANT
CEMENTATION PACKAGES
CUBIC CEMENT CONTAINERS (1.0 m3)
Thank you