Necesidad de educar en valores en la escuela

4. INPRO SUSTAINABILITY ASSESSMENT IN THE AREA OF

reactor and prevention / mitigation of off-site releases so that there will be no need for public evacuation’[7]. The user requirements specify how to achieve the goal:

 The nuclear reactor assessed is more robust than a reference design with regard to operation and systems, structures and components failures (robustness of design during normal operation);

 The nuclear reactor assessed has improved capabilities to detect and intercept deviations from normal operational states in order to prevent AOOs from escalating to accident conditions (detection and interception of AOOs);

 The frequency of occurrence of DBAs in the nuclear reactor assessed is reduced⁴⁵. If an accident occurs, engineered safety features are able to restore the reactor to a controlled state, and subsequently to a safe shutdown state, and ensure the confinement of radioactive material. Reliance on human intervention is minimal, and only required after a sufficient grace period;

 The frequency of an accidental release of radioactivity into the containment / confinement is reduced. If such a release occurs, the consequences are mitigated, preventing or reducing the frequency of occurrence of accidental release into the environment. The source term of the accidental release into the environment remains well within the envelope of the reference reactor source term and is so low that calculated consequences would not require evacuation of the public;

 An assessment is performed to demonstrate that the defence in depth (DID) levels are more independent from each other than in the reference design. To excel in safety and reliability, the nuclear reactor assessed strives for better elimination or minimization of hazards relative to the reference design by incorporating into its design an increased emphasis on inherently safe characteristics and/or passive systems, when appropriate;

 Safe operation of the nuclear reactor assessed is supported by accounting for human factor requirements in the design and operation of the plant, and by establishing and maintaining a strong safety culture in all organizations involved;

 The development of innovative design features of the nuclear reactor assessed includes associated research, development and demonstration (RD&D) to bring the knowledge of plant characteristics and the capability of analytical methods used for design and safety assessment to at least the same confidence level as for operating plants.

The developer of sustainable energy technology is expected to meet these user requirements.

INPRO assessor employs 28 criteria which can be used for checking the status of nuclear energy system in relation to the INPRO user requirements. Four of those criteria are divided in 21 evaluation parameters for clarity. The assessor procures a total of 45 items for the INPRO assessment in the area of reactor safety:

 Design of normal operation systems:

 Margins of design;

 Design simplification;

 Improved fabrication and construction;

 Improvement of materials;

 Redundancy of operational systems;

 Reactor performance:

 Margins of operation;

 Reliability of control systems;

45 Here and further in this section when the improvement of BN-1200 characteristics is discussed the reactor is compared with the reference design.

 Ageing management;

 Impact from incorrect human intervention;

 Sufficient technical documentation;

 Appropriate training programmes;

 Plant management organization;

 Use of worldwide operating experience;

 Inspection, testing and maintenance;

 Failures and deviations from normal operation;

 Occupational dose;

 Instrumentation and control (I&C) system and inherent characteristics:

 Continuous monitoring of plant health;

 Capability of I&C system;

 Compensation of deviations from normal operation;

 Grace periods after AOOs;

 Inertia;

 Frequency of DBAs;

 Grace period for DBAs;

 Engineered safety features;

 Barriers;

 Subcriticality margins;

 Frequency of release into containment / confinement;

 Robustness of containment / confinement design;

 Accident management;

 Frequency of accidental release into environment;

 Source term of accidental release into environment;

 Independence of DID levels;

 Minimization of hazards:

 Stored energy;

 Flammability;

 Excess reactivity in the core;

 Reactivity feedbacks;

 Criticality outside the reactor core;

 Passive safety systems;

 Human factors;

 Attitude to safety;

 Safety basis and safety issues;

 RD&D;

 Computer codes;

 Novelty;

 Safety assessment.

Several INPRO criteria in this area require comparing the reactor under assessment to the reference design. In the INPRO methodology area of reactor safety, a reference reactor (or design) is a reactor of the latest design operating in 2013. It should preferably be designed by the same corporate designer as the reactor assessed and using the same technology. Based on previous experience with INPRO assessments, the definition of date for the selection of the reference design helps to avoid potential misinterpretations of terms. Note that 2013 was the date selected at the beginning of the latest methodology update. This date should be revised periodically along with the rest of the INPRO methodology.

The reference design selected for this assessment, the BN-800 reactor in Beloyarsk NPP, was commissioned in 2016. This may create a few challenges for the INPRO study of the BN-1200 reactor. For example, the accumulated operating experience of BN-800 may be insufficient for the assessment of reactor performance. In such cases the data from BN-600 can be used to support the reference reactor data.

At the time of this report preparation the BN-1200 design has not been fully optimised and finalised. Further improvement of the safety characteristics and more detailed data on the reactor characteristics could be reasonably expected. However, input data compiled in the framework of this study and presented in this report are deemed to be sufficient for the limited scope INPRO assessment to inform the developers of BN-1200 on the actions to be taken and criteria to be met to achieve the system sustainability. The assessment (self-assessment) is expected to be completed in the future along with the development of detailed design of the reactor.