andra’s safety options of french underground facility … · a key milestone - the cigeo 2015...

S. Voinis, M. Rabardy, L. Griffault

Andra’s Safety Options of French underground

facility Cigéo- a milestone towards the licensing

application

IAEA international conference - Nov-2016

DISEF/DIR/16-0262

From 1991 towards the licensing application- successive

safety milestones

IAEA international

conference - Nov-2016 DISEF/DIR/16-0262

More than 25 years of acquisition of scientific and technical

knowledge and the development of safety methods appropriate to

deep geological disposal.

Since 2011, the DGR project entered an industrial design phase and

has become the Industrial Center for Geological Disposal- Cigéo

The Cigéo project will comprise consecutive phases:

IAEA international conference - Nov-

2016

An industrial pilot phase will start during the Cigeo’s initial construction and will end when

reaching repository’s routine operations. This phase comprises ‘inactive’ operations — such

as tests performed on installed equipment — and ‘active’ operations, i.e. operations in the

presence of waste packages

DISEF/DIR/16-0262

A Challenge is to be able to tell a story with solutions but also with open options to make it

« as evolutionary as possible ».

During operation, periodic safety examinations will be conducted

2- Transposition

zone of URL

results (proposed

2005)

Siting - A progressive and converging approach

Additional above-ground

geological survey 2007-2008

4- Location of

repository

surface facilities

to be presented

during the Public

Debate

Detailed

survey in

2010

1- Siting started in 1992 with a National

call for volunteering; URL licensed 1998

3- Area defined for location of repository U/G

facilities after local consultation (2009) and

detailed geological survey from the surface

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A Key milestone - The Cigeo 2015 Safety Options

According to article 6 of the French decree n° 1557 the 2nd

of November 2007 :

Submitting “Safety Options” is a possibility for nuclear operators to plan for

the construction license application process and the related ASN review of

their safety principles and approach

To begin the review process required as part of the construction license

application process

They do not constitute a safety demonstration

Nor a detailed description of the technical solutions

Nor a detailed description of scientific supporting evidence

Key objectives of the safety options:

Stabilize the safety standards reference documents, approaches, and input data, particularly

the package design assumptions used;

Stabilize the design and safety options and identify potential evolutions of the design;

Stabilize the various scenario categories (encompassing those used as the basis of design

calculations, those not included in DOS-Expl, normal evolution scenarios and "what-if"

scenarios);

Present an initial "bounding scenarios" impact assessment


2016 DISEF/DIR/16-0262

DISEF/DIR/16-0262

«classical » nuclear surface facility : Receiving, handling and preparing waste

packages

« underground nuclear

facility »

Depth > 500m

Limited geometry

Ramp ( ~ 4 km)

Post- closure phase

Specificity of Cigéo – Surface and underground

facilities

IAEA international

conference - Nov-2016

After the closure of the disposal facility, the

protection of human health and the environment

must not depend on institutional monitoring or

control as there is no certainty that this can be

maintained for more than a limited period

Safety options – a challenge issue - to show that all

families of waste envisaged to Cigéo are covered

Andra has integrated the various families of waste (around 100) and their level of

knowledge

For operational phase - The waste package is an important safety

component

Establishment of “sizing characteristics”

Allocation of operational safety functions between waste package components (

matrix, container, overpack..)

For post closure phase - The radiological inventory is an important

input for the post-closure quantitative safety assessment

Post-closure safety functions of waste packages

Application of factors of margins according to knowledge level

Distribution of the radioactivity inventory to have a safety demonstration independent

of delivery schedules for a bounding field for impact

Method to retain safety model for waste release

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Lifetime > 100,000 years, ~10,000 m3 of HLW,

~70,000 m3 of ILW-LL

60% of ILW-LL and 30% of HLW destined for Cigeo

have already been produced

Illustration - IL-LLW canisters : a wide variety of primary

packages

Design results mainly from operational requirements (

standardization , containment, criticality..)

concrete can contribute to post-closure safety (favorable conditions) but is not a

requirement (brings margin) – a need to verify that they do not disturb the safety

function ( e.g void , chemical ..)

7 models of canisters

ILLW

In concrete

6 different partitioning

design

6 different cover design

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IAEA international


There are plans for the

emplacement of each ILW

waste package family into one

specific vault of the

architecture.

However, as present

availability chronicles cannot

be granted till the closure

date, waste package families

have been re-arranged in

order to get conservative

(high) radioactive content

Illustration - A need to take into account the uncertainties

regarding the location of waste packages with time

Nuclear safety authority guidance

Need to adapt some of the rules currently applied to surface nuclear facilities to an underground

nuclear one (e.g. fire)

Need to adapt “ classical guidance” to take into account

the underground characteristics

Illustration on Fire Guidance

Two apparently “opposite”

approaches :

Nuclear approach

Underground construction/tunnel

approach

Necessity of reconciling these two approaches

Guidelines set up by Andra with the

contribution of fire experts

from nuclear operators

from various bodies (tunnels, firemen,

industrial risks)

DISEF/DIR/16-0262 IAEA international


IAEA international


1 – Operation safety functions 2 –Post closure safety functions

• Contain radioactive substances

• Limit dose rate

• Avoid criticality

• Avoid heat accumulation

• Avoid radiolysis gas accumulation

• Isolate the waste from surface

phenomena and human actions

• limit the transfer into the biosphere

of the radioactive substances and

toxic elements in the waste

1 oppose water flow;

2.limiting the release and immobilizing of

radionuclides and toxic elements

3.delaying and reducing the migration

Safety options - both operational and post-closure safety

functions and associated requirements

DISEF/DIR/16-0262

Very favourable characteristics of the Callovo-Oxfordien- the pillar for

post closure safety

Organization of the Layout and engineered barriers play complementary

rules

Post-closure safety

Main Safety options

Ramps/shaft seals

HLW ( vitrified matrix ,

overpack)

High depth : > 400 m

High thickness : > 140

m

Very low permeability

Stability with time

High capacity of

retention

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IAEA international


Complementarity of operational and post closure safety analysis

Both based on science/technological knowledge

DISEF/DIR/16-0262

Need to conduct operational and post closure safety

analysis in parallel

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The safety options present the four classes of post-closure

scenarios

Quantitative assessment of the scenarios (indicators)

Normal evolution domain Altered Evolution

Scenarios

Human Intrusion

scenarios

What-if scenarios

Normal Evolution Domain

To check that the disposal satisfies the protection objectives (radiological

and toxicological) and the safety functions

Consider expected evolution of the disposal (time and space) from its

closure to the long term

Assuming all safety functions are realized

Considering a set of evolutions which appear quite “probable” referring

to the NSA guide of 2008

Includes two situations

A reference situation considering the disposal as designed (assumptions

rely on the best available knowledge)

A situation based on the post-closure safety requirements applicable to

Cigéo and most conservative data when no specified requirements

Altered Evolution Scenarios and What-if scenarios

Identified through the qualitative

safety analysis of risks and

uncertainties

Based on the design and safety functions

and

Based on the scientific and technological

knowledges and associated residual

uncertainties

The understanding of internal

processes (including their coupling)

and their evolution with time

From the closure (initial state

at closure

To the long term (up to one

million years)

Includes a comparison with international

OECD FEP’s database of 2012

Comprehensiveness of the analysis

IAEA international


IAEA international


The malfunction scenarios - list of AES and what-if

malfunction scenarios of closure structures

3 AES Scenarios

Malfunctioning at the interface

between the clay core and the

Callovo-Oxfordian of seals (

surface-bottom, drift )

3 What-if Scenarios

Malfunctioning due to a

combined/cumuli of the clay

core failure and malfunction at

the interface between the clay

core and the Callovo-Oxfordian

IAEA international


Inadvertent human intrusion scenarios

Safety options presents dimensioning situations ,

excluded scenarios during operational phase


2016 DISEF/DIR/16-0262

Normal mode situations

corresponds to the operation of the facility which includes statuses and

operation including maintenance and scheduled shutdowns

Dimensioning incident and accident situations

All operating situations outside normal operation which may change the

protection of the interests but whose design measures limit the consequences

for the public and the environment

Dimensioning extension accident situations

Very unlikely situations which may occur following multiple failures of safety

systems or accumulations of events

Situations excluded

Physically impossible situations or situations for which a sufficient number of

measures enables exclusion

Illustration of main safety and design options

IAEA international


Use of proven equipment

Vertical descent = no feedback for such masses

Funicular = mostly used for transport of persons

Reduce fire risks and heat loads

Choice focused on funicular system compared to truck for the ramp,

Electric driven equipment

Using life rail (only emergency batteries)

Optimization: Water based hydraulic fluid

Reduce human occurrence and improve automation

Reduce human failure

Reduce dose rates

Illustration - Bounding dimensioning accident situations

and preliminary assessment

Room/zone Scenario Impact (mSv)

Unloading cell 6-meter fall of a primary waste unloaded by the overhead crane in an ET-V following

material failure of the lifting chain 10

-4

Unloading cell Cask fire involving a primary package at the centralized control station < mSV (0.4)

ILW-LL hot cell Fall of a disposal package following failure of the forklift

10-6

ILW-LL disposal cell Fire on stacking crane involving a disposal package < mSV (0.1)

IAEA international


Now and future …..

National review of all Cigéo 2015 files by the TSO :

Is ongoing …

Standing committee in May 2017 based on review report by IRSN

Official nuclear safety authority position mid 2017

International review by IAEA experts on behalf of the nuclear

safety authority (Focus on safety)

Seminar in mid November 2016

Official oral presentation on 2016 (positive views and

suggestions/recommendations towards licensing)

Andra is now preparing the overall safety case ( 2018) towards

the licensing application

IAEA international


Thank you for your attention

IAEA international


andra’s safety options of french underground facility … · a key milestone - the cigeo 2015...

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