INPRO basic principle for sustainability assessment of spent nuclear

INPRO basic principle for sustainability assessment of spent nuclear fuel storage facility in the area of safety: The planned spent nuclear fuel storage facility is safer than the reference spent

nuclear fuel storage facility. In the event of an accident, off-site releases of radionuclides and/or toxic chemicals are prevented or mitigated so that there will be no need for public evacuation⁶⁵. The rationale of the BP was provided in Section 5.2. An explanation on the requirement of superiority in the INPRO methodology area of NFCF safety is provided in section 6.3.1. The INPRO methodology has defined a set of requirements for spent fuel storage facilities as displayed in Table 30.

TABLE 30. INPRO USER REQUIREMENTS AND CRITERIA FOR SUSTAINABILITY ASSESSMENT OF SPENT NUCLEAR FUEL STORAGE FACILITIES IN THE AREA OF NFCF SAFETY

User requirement Criteria Indicator (IN) and Acceptance Limit (AL) UR1: Robustness of design during

normal operation:

The assessed SNF storage facility is more robust than the reference design with regard to operation and systems, structures and components

IN1.1: Robustness of design of normal operation systems.

AL1.1: Superior to that in the reference design.

CR1.2:

Subcriticality

IN1.2: Subcriticality margins.

AL1.2: Sufficient to cover uncertainties and avoid criticality.

CR1.3:

Facility performance

IN1.3: Facility performance attributes.

AL1.3: Superior to those in the reference design.

CR1.4:

Inspection, testing and maintenance

IN1.4: Capability to inspect, test and maintain.

AL1.4: Superior to that in the reference design.

IN1.5: Expected frequency of failures and deviations from normal operation.

AL1.5: Lower than that in the reference design.

AL1.6: Lower than the dose constraints.

UR2: Detection and interception of AOOs:

The assessed SNF storage facility has improved capabilities to detect and intercept deviations from normal operational states in order to prevent AOOs from escalating to

IN2.1: I&C system to monitor, detect, trigger alarms and, together with operator actions, intercept and compensate AOOs.

AL2.1: Availability of such systems and operator procedures.

CR2.2: Grace periods for AOOs

IN2.2: Grace periods until human actions are required after AOOs.

AL2.2: Adequate grace periods are defined in design analyses.

65 Other protective measures still may be needed. Effective emergency planning, preparedness and response capabilities will remain a prudent requirement as discussed in the INPRO methodology area of Infrastructure.

TABLE 30. INPRO USER REQUIREMENTS AND CRITERIA FOR SUSTAINABILITY ASSESSMENT OF SPENT NUCLEAR FUEL STORAGE FACILITIES IN THE AREA OF NFCF SAFETY (cont.)

User requirement Criteria Indicator (IN) and Acceptance Limit (AL) UR3: Design basis accidents:

The frequency of occurrence of DBAs in the assessed SNF storage facility is reduced. If an accident occurs, engineered safety features and/or operator actions are able to restore the assessed facility to a controlled state and subsequently to a safe state, and the consequences are mitigated to ensure the

AL3.1: Lower than that in the reference design.

AL3.2: Superior to those in the reference design.

CR3.3: Grace periods for DBAs

IN3.3: Grace periods for DBAs until human intervention is necessary.

AL3.3: Longer than those in the reference design.

IN3.5: Containment loads covered by design of the facility assessed.

AL3.5: Greater than those in the reference design.

UR4: Severe plant conditions:

The frequency of an accidental release of radioactivity into the environment is reduced. The source term of accidental release into the environment remains well within the envelope of the reference facility source term and is so low that calculated consequences would not equipment, and AM procedures and training to prevent an accidental release to the environment in the case of accident.

AL4.1: Sufficient to prevent an accidental release to the environment and regain control of the facility.

AL4.2: Lower than that in the reference facility.

AL4.3: Remains well within the inventory and characteristics envelope of the

reference facility source term and is so low that calculated consequences would not require evacuation of population.

TABLE 30. INPRO USER REQUIREMENTS AND CRITERIA FOR SUSTAINABILITY ASSESSMENT OF SPENT NUCLEAR FUEL STORAGE FACILITIES IN THE AREA OF NFCF SAFETY (cont.)

User requirement Criteria Indicator (IN) and Acceptance Limit (AL) UR5: Independence of DID levels

and inherent safety characteristics:

An assessment is performed for the SNF storage facility to demonstrate that the DID levels are more independent from each other than in the reference design. To excel in safety and reliability, the assessed SNF storage facility strives for better elimination or minimization of hazards relative to the reference design by incorporating into its

IN5.1: Independence of different levels of DID in the assessed SNF storage facility.

AL5.1: More independence of the DID levels is demonstrated compared to that in the reference design, e.g. through

IN5.2: Examples of hazards: fire, flooding, release of radioactive material, radiation exposure, etc.

AL5.2: Hazards minimized according to the state of the art.

UR6: Human factors related to safety:

Safe operation of the assessed SNF storage facility is supported by accounting for HF requirements in the design and operation of the facility, and by establishing and maintaining a strong safety culture in all organizations involved in the life cycle of the facility.

CR6.1: Human factors

IN6.1: Human factors addressed systematically over the life cycle of the SNF storage facility.

AL6.2: Evidence is provided by periodic safety reviews.

UR7: RD&D for advanced designs:

The development of innovative design features of the assessed SNF storage facility includes associated RD&D to bring the knowledge of facility characteristics and the capability of analytical methods used for design and safety assessment to at least the same confidence level as for operating facilities.

CR7.1: RD&D IN7.1: RD&D status.

AL7.1: RD&D defined, performed and