Conference PaperPDF Available

CAREM concept: A competitive SMR

Authors:

Abstract and Figures

CAREM concept is based in a cost effective primary system configuration. The use of an integrated primary cooling system, self-pressurization, internal control rod drives and boron free coolant are many of the distinctive features that characterize the system. In this paper CAREM is presented. This is an advanced reactor concept with new engineering solutions based in specific developments, the mature engineering of the prototype CAREM-25 and the wide worldwide experience in safe LWR operation.
Content may be subject to copyright.
1 Copyright © 2004 by ASME
Proceedings of ICONE12:
International Conference on Nuclear Engineering
April 25-29, 2004,Washington, D.C.
ICONE12-49140
CAREM CONCEPT: A COMPETITIVE SMR
Darío Delmastro
Centro Atómico Bariloche,8400 Bariloche, Argentina Marcelo Giménez
Centro Atómico Bariloche,8400 Bariloche, Argentina
Pablo C. Florido
Centro Atómico Bariloche,8400 Bariloche, Argentina Hernando Daverio
Centro Atómico Bariloche,8400 Bariloche, Argentina
Oscar Serra
Centro Atómico Bariloche,8400 Bariloche, Argentina Aníbal Blanco
Centro Atómico Bariloche,8400 Bariloche, Argentina
Pablo Mueller
Centro Atómico Bariloche,8400 Bariloche, Argentina
ABSTRACT
CAREM concept is based in a cost effective primary
system configuration. The use of an integrated primary cooling
system, self-pressurization, internal control rod drives and
boron free coolant are many of the distinctive features that
characterize the system.
In this paper CAREM is presented. This is an advanced
reactor concept with new engineering solutions based in
specific developments, the mature engineering of the prototype
CAREM-25 and the wide worldwide experience in safe LWR
operation.
INTRODUCTION
There is an important need of small nuclear power plants
suitable for developing countries and small or medium
developed countries utilities. At the present there is a lack of
NPP for this market when proved technologies (like LWR
technologies) are required together with ambitious economical
targets. CAREM concept is conceived to offer nuclear options
to this market, with an ambitious 1000 U$S/KWe overnight
cost for a 300 MWe nuclear power plant.
This project consists on the development, design and
construction of small nuclear power plants. First, a prototype of
an electrical output of about 27 MWe (CAREM-25) will be
constructed in order to validate the innovation of CAREM
concept. The advanced basic engineering of the prototype was
alredy completed and the PSAR was already submited. Several
sites are available for the prototype construction.
CAREM concept is based in a cost effective primary
system configuration. The use of an integrated primary cooling
system, self-pressurization, internal control rod drives and
boron free coolant are many of the distinctive features that
characterize the system.
CAREM has been recognized as an International Near
Term Deployment (INTD) reactor by the Generation IV
International Forum (GIF).
A proper safety balance by design is assured to avoid
jeopardizing reactor economic competitiveness. An innovative
methodology to perform or assist reactor design, balancing
safety and economics at the conceptual stage is used in
CAREM project. The key to this integral methodology is to
take into account safety aspects in an optimization design
process where the design variables are balanced in order to
obtain a better figure of merit related with reactor economic
performance. The design parameter effect on characteristic or
critical safety variables, chosen from the reactor behavior
during accidents (safety performance indicators), is synthesized
in Design Maps.
Proliferation resistance is another important aspect taken
into account in CAREM concept. CAREM design includes
isolated Material Balance Areas that contain all fissile material
and are remotely checked.
In this paper CAREM is presented. This is an advanced
reactor concept with new engineering solutions based in
specific developments, the mature engineering of the prototype
Proceedings of ICONE12
12th International Conference on Nuclear Engineering
April 25-29, 2004, Arlington, Virginia USA
ICONE12-49140
TRK-5 TOC
2 Copyright © 2004 by ASME
CAREM-25 and the wide worldwide experience in safe LWR
operation.
CAREM NUCLEAR POWER PLANT
The CAREM design is based on an integrated light water
reactor with slightly enriched uranium fuel. It is an indirect
cycle reactor with some distinctive features that greatly
simplify the design and also contribute to a high level of safety.
The main design characteristics are [1]:
Integrated primary cooling system
Primary cooling by natural or assisted circulation
depending on the module power
Self-pressurized
Passive safety systems
The primary cooling system is integrated. The reactor
pressure vessel (RPV) includes the core, the steam generators,
the whole primary coolant and the absorber rod drive
mechanisms.
For low power modules (below 150 MWe), the flow rate in
the reactor primary systems is achieved by natural circulation.
Figure 1 shows a diagram of the natural circulation of the
coolant in the primary system. Water enters the core from the
lower plenum. After been heated the coolant exits the core and
flows up through the riser to the upper dome. In the upper part,
water leaves the riser through lateral windows to the external
region. Then it flows down through modular steam generators,
decreasing its enthalpy. Finally, the coolant exits the steam
generators and flows down through the down-comer to the
lower plenum, closing the circuit. The driving forces obtained
by the differences in the density along the circuit are balanced
by the friction and form losses, producing the adequate flow
rate in the core in order to have the sufficient thermal margin to
critical phenomena. Reactor coolant natural circulation is
produced by the location of the steam generators above the
core. Coolant acts also as neutron moderator.
Figure 1 – CAREM Primary System Configuration
For high power modules (over 150Mwe) pumps are used to
achieve the flow rate needed to operate at full power. Different
pumps types and configurations are under consideration for
CAREM. This selection is a main issue because there is a
strong link between the RPV size, the pump characteristics, the
pressurising concept and safety systems, that strongly affects
the economy of the whole plant.
Twelve identical ‘Mini-helical’ vertical steam generators,
of the “once-through” type are placed equally distant from each
other along the inner surface of the Reactor Pressure Vessel
(RPV). They are used to transfer heat from the primary to the
secondary circuit, producing superheated dry steam.
The secondary system circulates upwards within the tubes,
while the primary goes in counter-current flow. An external
shell surrounding the outer coil layer and adequate seal form
the flow separation system. It guarantees that the entire stream
of the primary system flows through the steam generators.
Due to safety reasons, steam generators are designed to
withstand the primary pressure without pressure in the
secondary side and the whole live steam system is designed to
withstand primary pressure up to isolation valves (including the
steam outlet / water inlet headers) in case of SG tube breakage.
Self-pressurization of the primary system in the steam
dome is the result of the liquid-vapor equilibrium. The large
volume of the integral pressuriser also contributes to the
damping of eventual pressure perturbations. Due to self-
pressurisation, bulk temperature at core outlet corresponds to
saturation temperature at primary pressure. Heaters and
sprinkles typical of conventional PWR’s are thus eliminated.
The core of CAREM-300, a 300 MWe module, has 199
hexagonal cross section fuel assemblies (FA) having about 2.85
m active length. Each fuel assembly contains 108 fuel rods, 18
guide thimbles and 1 instrumentation thimble. The fuel
assembly components are similar to those of a conventional
PWR design. The core total thermal power is 900 MWth, with
147W/cm average linear power [2].
Core reactivity is controlled by Gd2O3 as burnable poison
in specific fuel rods and movable silver–indium-cadmium
absorber rods. The control rods drives are hydraulic and are
placed inside the RPV. Chemical compounds are not used for
reactivity control during normal operation. Fuel cycle can be
tailored to customer requirements, with a reference design of
330 full-power days and 33% of core replacement.
The design of the security systems fulfils the requirements
of the regulations of the nuclear industry as for redundancy,
independence, physical separation, diversification and failure
into a safe state.
CAREM safety systems must guarantee no need of active
actions to mitigate accidents for a long period.
CAREM has two different and independent shutdown
systems. These systems are designed to shutdown and to
maintain the reactor core sub-critical. They are activated by the
protection system reactor. The first system is designed to
shutdown the core reactor by dropping neutron-absorbing
elements into the core by the action of gravity. The second
shutdown system is based on the injection of borated water to
the core, also by the action of gravity.
The residual heat of the core, in station blackout, is
removed by passive principles (natural convection) through the
residual heat removal system. This system transfers this energy
to the pressure suppression pool.
3 Copyright © 2004 by ASME
CAREM has an emergency injection system to prevent
core exposure in case of loss of coolant accident (LOCA). This
system assures the correct refrigeration of core reactor without
electric power supply.
The RPV integrity is additionally ensured by three safety
relief valves. They protect the RPV against overpressures and
each valve has 100% of the necessary relief capacity.
CAREM has a containment isolation -pressure-suppression
type- to retain the eventual liberation of radio-active materials.
Its design is such that after having begun any unlike accident
with loss of coolant, and without any external action, the
pressure inside stays below the design pressure.
In the figure 2 an outline of the containment and safety
systems are shown.
Figure 2 – Safety System and Containment
CAREM AND THE COST EFFECTIVE
INTERNALIZATION OF NUCLEAR SAFETY
Reactor design is an intrinsically complex task, due to the
quantity of parameters whose dimensions have to be
determined and the existing relations between them. At the
engineering conceptual stage, quantifying the influence of
mechanics, thermal-hydraulic, neutronic and safety on reactor
costs is of interest. A breakdown of the main items that affect
costs must be performed with the purpose of finding a unit cost
for the generated energy, a figure of merit of the alternative
designs.
Under the program of CAREM integral type reactor, a
computational tool is been developed to perform the above
mentioned tasks as support to the design team during the
conceptual stage. This code, called IREP+NS –Integrated
Reactor Evaluation Program plus Nuclear Safety–, makes the
necessary internal iterations to obtain a coherent set of design
and operational parameters that define a reactor, considering
the main feedback existing between these parameters. This
code also allows the designers to optimize economically the
most important parameters of the core, primary, safety systems
and secondary systems, in order to reduce the cost of electricity
generation.
Although the current methodologies, classical or more
advanced ones, like a steady state optimization, fulfil the
requirements of design relative to safety, the lack of balance
between economy and safety is evident. It is necessary that
economy and safety should be evaluated together in the
conceptual design stage, to balance properly these two
fundamental aspects of design. It is important to perform this
process with a global approach, contemplating the design
feedback between all the systems and involved areas. Safety
aspects are part of the most important contributors to costs,
hence they must be considered in an efficient way. As other
authors have already noticed, the new approach must consider
new methods for cost-benefit and ALARA analyses, employing
modern PSA techniques and fulfilling basic safety requirements
instead of overly detailed prescriptions, with realistic models
and assumptions.
The conceptual global design process in order to design the
reactor to be safe and competitive, performing an integral
optimization of the design parameters, can be resumed in the
following stages considering the above analysis [3]:
1) Preliminary conceptual design and qualitative
optimization based on designers’ judgment. Stage based on
designers’ expertise and research results, recognizing
alternatives that aim to simplify the design and to reduce
initiating events and diminish their incidence, among other
design goals. Different alternatives for safety and process
systems are proposed at this stage, for being evaluated in the
next one. Thus, the design basis is now obtained.
2) Integrated conceptual design and quantitative
optimization. This second stage consists in an integral design
optimization process in order to improve a figure of merit. To
perform this, neutronic, thermal-hydraulic, mechanical, safety
and economical dimensioning modules are required. Safety
ones are employed to simulate the plant performance in steady
state and in transients or accidents and to characterize it by
means of safety performance indicators. This evaluation is
performed for each set of parameters that defines a possible
reactor design that may be found during the optimization
process. Safety goals determined by regulators and designers
are embodied in practical quantitative safety targets. They are
applied as limits to the selected safety performance indicators
and therefore considered as restrictions on the design
parameters. Then, the economic figure of merit is calculated
given the main design parameter values. Finally, the
optimization gives a new set of parameters improving the value
of the figure of merit. This stage is repeated until the design
converges.
3) Final conceptual design stage based on experts’
judgement. Evaluating the alternatives results, the best design
options are chosen. Eventually, feedback to previous steps will
be necessary.
In order to face the posed design optimization problem, an
objective is selected, a feature that is being analyzed and should
be reached with the design. It is a result of the design
parameters, which witnesses how good or bad a design is, in
relation to the proposed goal. It is called figure of merit.
Aiming at designing competitive nuclear power plants, adopted
strategies may include the reduction of capital costs or other
economic figures of merit. Several results of the design process
4 Copyright © 2004 by ASME
can be selected as figure of merit for economical optimization.
They are typically electricity generation cost, cost of
investment by power unit ($/kw), total investment cost
(releasing power as a parameter to optimize) and net present
value of the project (assuming a known price of sale of the
energy unit).
To verify reactor safety criteria fulfilment, the concept of
safety performance indicators is introduced, also known as
observable variables. Each one of these variables is chosen in
order to characterize and represent reactor safety levels or
reactor degree of exigency during an accidental sequence. The
idea is that for each accidental sequence, one or more indicators
can be defined. Deterministic and probabilistic safety
performance indicators are also supported by the methodology.
An example of a safety indicator is the time that the water level
inside the RPV in an integral-type PWR takes to reach the core
top during a loss of coolant accident (LOCA). The maximum
fuel or cladding temperature reached during a reactivity
insertion accident, the DNBR minimum in time and space
reached in a main steam line rupture or the maximum pressure
during a loss of heat sink sequence could be other ones.
Probabilistic safety indicators, such as core damage frequency,
unavailability of the safety systems can also be considered.
Operational performance indicators are studied in reference.
There are also restrictions, which are limits that a particular
design must fulfil and are applied to the design parameters as
well as to the safety indicators. It is evident that the value of
each safety indicator will be function of the design parameters.
During the optimization process developed, while looking for
an appropriate set of design parameters that optimizes a given
figure of merit related with cost, safety indicators are compared
with imposed limits. Should any of these limits be violated, the
direction of the design parameters movement is changed in
order to keep the reactor safe enough. Therefore, the safety
indicators will be used to evaluate the safety degree and to
determine the direction the design parameters must move
towards, within the general scheme of optimization, as
explained below.
Considering then that the design parameters influence the
safety indicators, the concept of Design Map is reached [4]. A
Design Map is a representation of this dependence and allows
to introduce restrictions to the safety performance indicators in
order to translate them to the design parameters, limiting
therefore the optimization domain.
One of the options for creating design maps is to
accomplish this a priori, before carrying out the optimisation
process. In order to perform this, each design parameter
amplitude and discretisation needs to be defined. The n-
dimensional matrix of design parameters is then scanned,
simulating the different accident sequences for each possible
reactor design. The resultant safety indicators, along with the
set of design parameters, are stored in disc, to be then accessed
from the optimiser as a database. An alternative approach is to
obtain the safety indicators values while the optimisation is
being carried out, which would be an online method of map
calculation. Both alternatives make several calls to reactor
calculation models, which indicates that models must be as
simple as possible, to reduce the computing time. This must be
taken into account when choosing one of the options. For either
alternative, in each step the safety indicators of the
correspondent design parameter set is obtained.
It is important to mention that as this methodology is
applied at the conceptual engineering stage, models for accident
simulation are therefore relatively simple and sufficient
conservativeness must be assured.
For example, to cope with the larger Loss of Coolant
Accident different Injection System volumes are needed
depending on the Maximum Containment Pressure and the
grace time before any operator action is required. Figure 3
shows the CAREM-300 Injection System Volume vs.
Maximum Containment Pressure for different grace times.
12345
0,5
0,6
0,7
0,8
0,9
1,0
1,1
1,2
1,3
1,4
1,5
Relative Injection System Volume
Maximum Containment Pressure [atm]
Grace Time
24 h
36 h
48 h
60 h
72 h
Figure 3 – CAREM-300 Injection System Volume vs.
Maximum Containment Pressure Design Map.
Having created the design maps, the process goes on
with the optimisation of the parameters that influence the
selected figure of merit. In order to do this, an optimisation
routine should be followed which, step by step, gives a new
parameter set of the reactor design, with the objective to
improve the value of the figure of merit and simultaneously
fulfilling the design criteria relative to safety restrictions. A
flow chart of all this process is shown in Figure 4 [3].
Optimisation
Operational
and design
parameters
Steady State
Dimensioning
Inicial
Design Reactor Cost
Parameters
to optimise
Observable:
Safety Indicator Figure
of Merit to improve
Variable
Parameters
Design Maps
Figure 4 - Calculation diagram. Figure of merit: reactor cost
5 Copyright © 2004 by ASME
Besides verifying safety criteria, the safety indicators
can be also considered as a figure of merit to be improved
instead of a cost-related one. Cost-related or other design
restrictions can either be considered or not, depending on the
designers’ choice. For instance, this could be used to find a
feasible design (one that does not violate any restriction) when
some safety restrictions are being violated, for a posterior
economic optimization inside the feasible design region. Other
uses would be to search the safest design alternative for a given
generation cost or the “safest limited-budget design”. The
safety criteria fulfilment could be verified after these ALARA-
like optimizations take place. The flow chart of this process is
shown in Figure 5 [3].
Optimisation
Operational
and design
parameters
Steady State
Dimensioning
Inicial
Design Reactor Cost
Parameters
to optimise
Figure of merit:
Safety Indicator Observables
Variable
Parameters
Design Maps
Other Safety Indicators
Figure 5 - Calculation diagram. Figure of merit: Safety
performance indicator
An application of the methodology embodied in IREP+SN
was presented in [5] and consists in balancing the designs of the
Emergency Injection System, the Residual Heat Removal
System, the Primary water inventory and the Containment
height of CAREM, considering the reactor performance to cope
with Loss Of Coolant and Loss Of Heat Sink Accident
sequences. A criterion to determine the maximal break area,
that the penetrations to the Reactor Pressure Vessel might
cause, is obtained as a by-product. The safety performance
indicators selected for the former accidents’ scenarios are the
core uncovery time and the minimal mass margin, whereas the
maximal pressure is the critical variable for the latter ones.
SAFEGUARD IMPLEMENTATION
Two isolated Material Balance Areas (MBA) for irradiated
fuel are included in CAREM concept approach in order to
facilitate safeguard implementation and reduce safeguard costs.
One is the pressure vessel and the other is the spent fuel pool.
This two MBAs have all the irradiated fuel and allow integrity
check by remote systems. During reactor operation there is no
physical way to get access to this fissile material.
To increase proliferation resistance all the refueling tasks
will be developed in the reactor hall, which is designed to allow
remote monitoring of all nuclear material handling. The
entrance-exit and the interfaces have been designed to allow the
counting of the items during they movement.
This approach allows a reduction of safeguard costs of
about 10 to 20% [1].
CAREM ECONOMY
CAREM concept economy was analyzed using IREP code
[6]. Figure 6 shows the results obtained for different power
modules [7]. Below 150 MWe the natural convection option is
preferable because the estimated costs are similar and the
present version of IREP results more representative for this
configuration. Over that power the size and cost of the RPV are
outside the acceptable range so the Forced Convection option is
preferable.
20
30
40
50
60
TUEC
Costs
[mills/
KWh]
050 100 150 200 250 300
Electric Powe r [MWe]
Natural Convection Forced Convection
Figure 6 – Total generation cost for different CAREM
modules
CONCLUSIONS
To reach the 1000 U$S/KWe overnight cost for a 300MWe
integrated reactor module is a very difficult task.
IREP+SN code approach, considering stationary and
transient conditions, implies a delicate balance between cost
and performance of components and systems. The experience
shows that without this approach at 300MWe LWR technology
has important difficulties to reach this target. For example,
operational and safety constraints on RPV size are not
compatible with the optimal pure stationary integrated design.
REFERENCES
1. D. Delmastro, M. Giménez, M. Schlamp, P. Florido, J.
Bergallo, “CAREM concept: A cost effective innovative LWR
for small and medium utilities”, International Conference on
Innovative Technologies forNuclear Fuel Cycles and Nuclear
Power, June 2003, Vienna, Austria.
2. D. Delmastro, M. Gimenez, P. Florido, H. Daverio, O.
Serra y A. Blanco, “Carem-300: un reactor competitivo”, LAS-
ANS 2003 Symposium, Santiago de Chile, Agosto 2003.
3. M. Giménez, P. Grinblat and M. Schlamp, A cost-
effective methodology to internalize nuclear safety in nuclear
reactor conceptual design, Nuclear Engineering and Design,
226/3 pp. 293-309, 2003
6 Copyright © 2004 by ASME
4. P. Zanocco, M. Giménez y D. Delmastro, Safety design
maps: an early evaluation of safety to address reactor design,
Nuclear Engineering and Design, 2003, Vol. 225/2-3 pp. 269-
281, 2003
5. P. Grinblat, M. Giménez and M. Schlamp, CAREM:
Nuclear Safety Internalized Cost-Effectively from the Concept
Genesis , International Congress on Advanced Nuclear Power
Plants, ICAPP03, Córdoba, España, Mayo 2003 (in
Proceedings).
6. Rubiolo, P., Florido, P., Ordoñez, J., Guido Lavalle, G.
and Masriera, N.: “Evaluation of the Conceptual Design of
Integrated PWRs and the CAREM Project”. International
Symposium on Desalination of Seawater with Nuclear Energy.
Taejon, Korea, 1997 (in Proceedings).
7. Florido, P., Bergallo, J. and Ishida, M.: “Argentinean
integrated small reactor design and scale economy analysis of
integrated reactor”. 3rd International Conference on Nuclear
Option in Countries with Small and Medium Electricity Grids.
Dubrovnik, Croacia, 2000.
Article
The Integrated Pressurized Water Reactor (IPWR) designed with series of passive safety system has been regarded as a very promising reactor concept. In this paper, in order to assess the accident mitigation ability of passive safety systems in China 100 MW IPWR, the complete system models, including the reactor vessel, passive safety injection system and passive residual heat removal system, were established using RELAP5 software. The comprehensive and quantitative comparative analysis of auxiliary feed water system and passive safety system under typical accident scenarios, including loss of flow accident and Station Black-out (SBO), were investigated, respectively. Results show that the passive residual heat removal system has the similar accident mitigation capability compared with the auxiliary feed water system, which is adopted in most of traditional PWR design. And the IPWR could realize the reactor safe shutdown under typical accident scenarios with passive safety systems. Finally, the Small break loss of coolant accident (SBLOCA) induced by pressurizer surge line rupture was calculated to verify the function of passive safety systems for IPWR. Results demonstrate that the passive safety system could provide emergency coolant to the reactor and remove the reactor decay heat successfully. This work is meaningful for the quantitative evaluation of passive safety systems in IPWR.
Article
Full-text available
2 Avenida del Libertador 8250 (1425) Capital Federal, Argentina 1. ABSTRACT This paper describes the design of CAREM, which is Argentinean integrated small reactor project and the scale economy analysis results of integrated reactor. CAREM project consists on the development, design and construction of a small nuclear power plant. CAREM is an advanced reactor conceived with new generation design solutions and standing on the large experience accumulated in the safe operation of Light Water Reactors. The CAREM is an indirect cycle reactor with some distinctive and characteristic features that greatly simplify the reactor and also contribute to a highly level of safety: integrated primary cooling system, self pressurized, primary cooling by natural circulation and safety system relying on passive features. For a fully coupled economic evaluation of integrated reactors done by IREP (Integrated Reactor Evaluation Program) code transferred to IAEA, CAREM have been used as a reference point. The results shows that integrated reactors become competitive with power larger than 200MWe with Argentinean cheapest electricity option. Due to reactor pressure vessel construction limit, low pressure drop steam generator are used to reach power output of 200MWe for natural circulation. For forced circulation, 300MWe can be achieved.
Article
A novel methodology to perform nuclear reactor design and a particular application to CAREM prototype reactor are presented in this work. The methodology achieves to balance efficiently safety and economics at the conceptual engineering stage. The key to this integral approach is to take into account safety aspects in a design optimization process where the design variables are balanced in order to obtain a better figure of merit related with reactor economic performance. Design parameter effects on characteristic or critical safety variables, chosen from reactor behavior during accidents and from its probabilistic safety assessment-safety performance indicators-, are synthesized on Safety Design Maps. These maps allow one to compare these indicators with limit values, which are determined by design criteria or regulations, and to transfer these restrictions to the design parameters. In this way, reactor dynamic response and other safety aspects are integrated in a global optimization process, by means of additional rules to the neutronic, thermal-hydraulic and mechanical calculations. This advanced safety based design optimization has been implemented in a computer-aided design and analysis tool called IREP3. This code allows the design team to balance and optimize reactor and safety system design in an early engineering stage, in order to internalize cost-efficiently safety issues. It also allows one to evaluate the incremental costs of implementing higher safety levels. Furthermore, through this methodology, a simplified design can be obtained, compared to the resultant complexity when these concepts are introduced in a later engineering stage. The particular case presented in this work, an application of the methodology embodied in IREP 3, consists in balancing the designs of the Emergency Injection System, the Residual Heat Removal System, the Primary water inventory and the Containment height of CAREM, considering the reactor performance to cope with Loss Of Coolant and Loss Of Heat Sink Accident sequences. A criterion to determine the maximal break area, that the penetrations to the Reactor Pressure Vessel might cause, is obtained as a by-product. The safety performance indicators selected for the former accidents' scenarios are the core uncovery time and the minimal mass margin, whereas the maximal pressure is the critical variable for the latter ones.
Article
A new tendency in nuclear reactor conceptual design is to include safety criteria through accident analysis to address the selection of the engineering solutions and the value of the main design parameters. In this work, the concept of design map is used to correlate reactor safety performance with the design parameters. The effect of different design parameters on characteristic safety variables, referred to as “observable variables,” extracted from reactor evolution during accidents, is analyzed, and the concept of “safety design maps” is introduced. The sensitivity of these “observables variables” regarding changes in design parameters is visualized.Several safety design maps are built from the performance of an integral type reactor during loss of heat sink (LOHS) and main steam line break sequences without SCRAM to show the technique potentiality. Maximum reactor pressure vessel (RPV) pressure and minimum departure from nucleate boiling ratio are chosen as “observable variables” and their sensitivity to geometry-related parameters and reactivity coefficient is studied. Multiple-parameter single design maps and combined design maps for both accidental sequences are built as examples. The results show the usefulness of this technique to balance and optimize reactor design through an early engineering step.A computer code (HUARPE) has been developed in order to simulate these transients. The cooling circuit, the steam dome, the pressure vessel structures and core models are considered.
Article
A new methodology to perform nuclear reactor design, balancing safety and economics at the conceptual engineering stage, is presented in this work. The goal of this integral methodology is to take into account safety aspects in an optimization design process where the design variables are balanced in order to obtain a better figure of merit related with reactor economic performance. Design parameter effects on characteristic or critical safety variables, chosen from reactor behavior during accidents (safety performance indicators), are synthesized on Design Maps. These maps allow one to compare the safety indicator with limits, which are determined by design criteria or regulations, and to transfer these restrictions to the design parameters. In this way, reactor dynamic response and other safety aspects are integrated in a global optimization process, by means of additional rules to the neutronic, thermal-hydraulic, and mechanical calculations.An application of the methodology, implemented in Integrated Reactor Evaluation Program 3 (IREP3) code, to optimize safety systems of CAREM prototype is presented. It consists in balancing the designs of the Emergency Injection System (EIS), the Residual Heat Removal System (RHRS), the primary circuit water inventory and the containment height, to cope with loss of coolant and loss of heat sink (LOHS) accidental sequences, taking into account cost and reactor performance.This methodology turns out to be promising to internalize cost-efficiently safety issues. It also allows one to evaluate the incremental costs of implementing higher safety levels.
Carem-300: un reactor competitivo
  • A Serra
  • Blanco
Serra y A. Blanco, "Carem-300: un reactor competitivo", LASANS 2003 Symposium, Santiago de Chile, Agosto 2003.
CAREM concept: A cost effective innovative LWR for small and medium utilities
  • Bergallo
Bergallo, "CAREM concept: A cost effective innovative LWR for small and medium utilities", International Conference on Innovative Technologies forNuclear Fuel Cycles and Nuclear Power, June 2003, Vienna, Austria. 2. D. Delmastro, M. Gimenez, P. Florido, H. Daverio, O.
Evaluation of the Conceptual Design of Integrated PWRs and the CAREM Project
  • P Rubiolo
  • P Florido
  • J Ordoñez
  • G Guido Lavalle
  • N Masriera
Rubiolo, P., Florido, P., Ordoñez, J., Guido Lavalle, G. and Masriera, N.: "Evaluation of the Conceptual Design of Integrated PWRs and the CAREM Project". International Symposium on Desalination of Seawater with Nuclear Energy. Taejon, Korea, 1997 (in Proceedings).
CAREM concept: A cost effective innovative LWR for small and medium utilities
  • D Delmastro
  • M Giménez
  • M Schlamp
  • P Florido
  • J Bergallo
D. Delmastro, M. Giménez, M. Schlamp, P. Florido, J. Bergallo, "CAREM concept: A cost effective innovative LWR for small and medium utilities", International Conference on Innovative Technologies forNuclear Fuel Cycles and Nuclear Power, June 2003, Vienna, Austria.
Carem-300: un reactor competitivo
  • D Delmastro
  • M Gimenez
  • P Florido
  • H Daverio
  • O Serra
  • A Blanco
D. Delmastro, M. Gimenez, P. Florido, H. Daverio, O. Serra y A. Blanco, "Carem-300: un reactor competitivo", LAS-ANS 2003 Symposium, Santiago de Chile, Agosto 2003.