INPRO Methodology requirements on

Safety of Nuclear Reactors

IAEA/INPRO group

Dialog Forum-7: Sustainability of NES based on evolutionary reactors.

Vienna, 19-22 November, 2013

2

Introduction

- goals for development

of sustainable NES

- actions to be done to

meet the goal

- assessor’s tools to

check whether the

actions are done

properly

Architecture of the INPRO requirements

Basic Principles

User

Requirements

Criteria (indicators + acceptance limits)

General characteristics of the INPRO Methodology in

the area of safety:

• Assessment of the progress achieved for specific technology

rather than comparison of technologies;

• Largest INPRO area (approx.1/3 of total assessment items);

• Priority of the area of safety;

• No roadblocks expected for evolutionary designs;

• Most challenging – detailed study necessary to identify gaps;

• NESA support package developed to reduce efforts;

• Dialog Forum 7 meeting materials will be included into the support

package.

Introduction3

4

Introduction

• Fundamental Nuclear Safety Objective (IAEA Safety Standard SF-1): “To protect people and the environment from harmful effects of ionizing radiation”.

• INPRO methodology in the area of safety is based on the IAEA Safety Standards, and on extrapolation of current trends assuming a large increase of NP in the 21st century.

• To meet this objective the measures have to be taken to

achieve the following:• Control radiation exposure of people and the release of

radioactive material to the environment;

• Restrict the likelihood of events that might lead to loss of control over the reactor core and other sources of radioactive material associated with the reactor core;

• Mitigate the consequences of such events if they were to occur.

5

Introduction

Basic Principles and User Requirements in the INPRO

safety area:

BP1: Enhance defence in depth

BP2: Emphasize inherent safety and passive systems

BP3: Radiation risk comparable to other industrial facilities

BP4: Sufficient R&D for innovative designs

Fundamental

nuclear safety principles

(INSAG-12)

Group 1. Management

responsibilities:

Safety culture;

Responsibility of operator;

Regulatory control.

Group 2. Strategy of

defence in depth:

Defence-in-depth;

Accident prevention;

Accident mitigation.

Group 3. General technical

principles:

Proven engineering practices;

Radiation protection;

Quality assurance;

Human factors;

Peer reviews; etc.

Considered in the INPRO

area of Infrastructure

• Objective of the INPRO assessment in the area of safety is to

confirm the long term sustainability of a NES, i.e. INPRO

criteria may be different from licensing criteria;

• INPRO methodology is a sustainability assessment method:

• Safety Analysis and INPRO assessment are two consecutive steps;

• Safety Analysis is necessary prerequisite for INPRO assessment in the

area of Safety – INPRO assessor needs results of analysis as input to

perform judgements whether INPRO criteria are met;

• INPRO assessment in the area of Safety is not a Safety Assessment

using the IAEA Safety Standards (as defined in the IAEA Safety

glossary).

INPRO assessment of sustainability and

Safety Assessment

6

7

Method of INPRO assessment

• Step 1: Collect input data (both for NES to be assessedand a Reference Design*, operating end of 2004):• Information on NPP component and system design (e.g., thermal,

mechanical, electrical, neutronics, I&C, etc.).

• Information from safety analysis (deterministic and probabilistic) of all initiating events, e.g., AOO, DBA and BDBA, frequencies and consequences.

• Information on R&D results for innovative features of a NPP.

• Step 2: Check whether an INPRO Criterion (CR) is fulfilled.• Criterion is met if Indicator (IN) meets its Acceptance Limit (AL).

• If a CR is not met follow-up action (-s) to meet the CR are to be defined.

* Newest reactor operating end of 2004, is the reference design to be compared against (i.e. enhanced DID, more independent levels).

8

Area of safety

BP1 BP2 BP3 BP4

1.1 1.2 1.4 1.5 1.61.3 1.7 2.1 3.1 3.2 4.44.34.24.1

1.1.1

1.1.2

1.1.3

1.1.4

E

E

E

E

E

E

E

E

E

E

EE

E

1.2.1

1.2.2

1.2.3

E

E

1.3.1

1.3.2

1.3.3

1.3.4

1.3.5

1.3.6

1.4.1

1.4.2

1.4.3

1.4.4

1.5.1

1.5.2

1.5.3 1.6.1

1.7.1

1.7.2

2.1.1

2.1.2

2.1.3

2.1.4

E

E

E

E

EE

3.1.1 3.2.1

4.1.1

4.1.2

4.2.1

4.2.2

4.2.3

4.3.1

4.3.2

4.4.1

4.4.2

BP – 4; UR – 14; CR + EP =55.

Structure of the INPRO area of Safety

9

Structure of first Basic Principle BP1C

orresp

on

d to

five lev

els of D

iD

Area of safety

BP1 Enhance

defence in depth

BP2 Emphasize

inherent safety and

passive systems

BP3 Radiation risk

comparable to

industrial facilities

BP4 Sufficient R&D

for innovations

BP1: NES shall incorporate enhanced defence-in-depth

as a part of their fundamental safety approach and ensure

that the levels of protection in defence-in-depth shall be

more independent from each other than in existing

installations

UR1.1 increase of robustness

UR1.2 detection and

interception of deviations

UR1.3 reduction of frequency

of DBA

UR1.4 reduction of frequency

of release into containment

UR1.5 prevention of release

to outside

UR1.6 independence of DiD

levels

UR1.7 improvement of

Human Machine Interface

10

First Basic Principle BP1: enhance DID

IAEA INSAG-10. Objectives for DID INPRO. Innovation directions

Level 1. Prevention of abnormal

operation

Increase inherent safety, reduce human

actions*.

Level 2. Detection and control of

abnormal operation.

Advanced control and monitoring systems.

Level 3. Control of accidents within the

design basis.

Combination of active and passive features;

minimize needed human intervention*.

Level 4. Control of severe plant

conditions, including prevention and

mitigation of the accident consequences.

Enhanced systems to control and monitor;

decrease frequency of severe plant

conditions.

Level 5. Mitigation of consequences of

significant releases of radioactive materials.

Avoid need for evacuation or relocation.

* - DID concept protects against failures and human errors.

What is “enhanced defence-in-depth” (DiD)?

11

Structure of first User Requirement UR1.1

Acceptance Limit AL: New design should

be superior to Reference Design

UR1.1 Increase

of robustness

CR1.1.1 Robustness of

design (simplicity, margins)

CR1.1.2 High quality of

operation

CR1.1.3 Capability to

inspect

CR1.1.4 Expected frequency

of failures and disturbances

UR1.1: Installations of a NES should be more

robust relative to existing designs regarding

system and component failures as well as

operation

Robustness of design can be

achieved by an increase of:• Margins of design;

• Simplicity of design;

• Quality of manufacture &

construction;

• Quality of materials;

• Redundancy of systems.

12

Structure of forth User Requirement UR1.4

UR1.4 Internal

release

CR1.4.1 Frequency of major

release of radioactive

material into containment

CR1.4.2 Natural or

engineered processes for

controlling parameters in

containment

CR1.4.3 In plant severe

accident management

UR1.4: The frequency of a major release of

radioactivity into the containment of a NES should be

reduced. Should a release occur, the consequences

should be mitigated

• Major release into containment occurs

after failure of engineered safety features

to keep or restore controlled state;

• Loss of integrity of RPV possible;

• Frequency is to be determined by PSA;

• For operating power plants IAEA

recommends the frequency <10-5/a;

• INPRO recommends for sustainable NES

the calculated frequency of major release

of radioactive materials into the

containment is to be <10-6/a and even

lower for installations at urban sites.

13INPRO requirements to frequencies and

consequences of accidents

Consequences

(dose, damage)

DBA

BDBA

- Groups of accidents in reference plant

- Groups of accidents in new NES

- NES release requiring evacuation or

relocation should be prevented

Frequency of

occurrence

DBA BDBA

14

Structure of second Basic Principle BP2

UR2.1 Elimination or

minimization of hazards

Area of safety

BP1 Enhance

defence in depth

BP2 Emphasize

inherent safety and

passive systems

BP3 Radiation risk

comparable to

industrial facilities

BP4 Sufficient R&D

for innovations

BP2: Installations of an NES shall excel in safety and reliability

by incorporating into their designs, when appropriate, increased

emphasis on inherently safe characteristics and passive systems

as a part of their fundamental safety approach

15

Structure of User Requirement UR2.1

Acceptance Limit: New design should

be superior to Reference Design

UR2.1 Elimination or

minimization of hazards

CR2.1.1 Indicators of

hazards

CR2.1.2 Expected

frequency of abnormal

operation and accidents

CR2.1.3 Consequences of

abnormal operation and

accidents

CR2.1.4 Confidence in

innovative components and

approaches

UR2.1: NES should strive for elimination or

minimization of some hazards relative to existing

plants by incorporating inherently safe characteristics

and/or passive systems, when appropriate

Sample indicators :

• Stored energy

• Flammability

• Criticality

• Inventory of radioactive material

• Excess reactivity

• Reactivity feedback

16

Structure of third Basic Principle BP3

UR3.1 dose to workers

UR3.2 dose to the public

(reduced by concept of

optimization, and for increased

flexibility in siting)

• BP3 covers risk from radiation during NO and AOO, i.e. level 1 and 2 of DiD, for workers, public and environment (risk to public after severe accident is covered by UR1.5).

• Operational risk of NES should be comparable to alternative energy sources.

Area of safety

BP1 Enhance

defence in depth

BP2 Emphasize

inherent safety and

passive systems

BP3 Radiation risk

comparable to

industrial facilities

BP4 Sufficient R&D

for innovations

BP3: NES shall ensure that the risk from radiation

exposures to workers and public during construction/

commissioning, operation, and decommissioning, shall be

comparable to that of other industrial facilities used for

similar purposes.

17

Structure of forth Basic Principle BP4

BP4: The development of NES shall include

associated RD&D work 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 existing plants

UR4.1 safety basis

UR4.2 R&D for

understanding

UR4.3 reduced scale pilot

plant or large scale

demonstration facility

UR4.4 safety analysis

using both deterministic

and probabilistic methods

Area of safety

BP1 Enhance

defence in depth

BP2 Emphasize

inherent safety and

passive systems

BP3 Radiation risk

comparable to

industrial facilities

BP4 Sufficient R&D

for innovations

18

Summary

• INPRO methodology is a holistic system approach, safety of

reactor is only one aspect of long term sustainability.

• INPRO acknowledges the high safety standard of modern

operating NPPs. To maintain these standards with a large

increase in the number of NPPs it will require an increased

safety level in new reactors.

• In the area of safety of nuclear reactors INPRO has defined:

• 4 Basic Principles.

• 14 User Requirements.

• 38 Criteria.

• INPRO requirements in the area of safety are mainly

recommendations for NES developers.

19

Summary (cont.)

• To increase the safety level of new reactors INPRO asks the designer to:• Enhance the concept of defense in depth in new reactor

design;

• Include inherent safety characteristics and passive safety systems into the design to minimize hazards;

• Lower the health risk of new reactors to a level comparable with non nuclear facilities;

• Perform sufficient R&D for all innovative design features of new reactors.

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Thank you for your attention