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Hitachi-GE Nuclear Energy, Ltd. Proprietary Information IAEA International Conference on Topical Issues in Nuclear Installation Safety: Safety Demonstration of Advanced Water Cooled Nuclear Power Plants Vienna, Austria, 6–9 June 2017 RISK-INFORMED DESIGN FOR UK ABWR PROJECT Yuki Ishiwatari (Hitachi-GE Nuclear Energy, Ltd.) Kohei Hisamochi (Hitachi-GE Nuclear Energy, Ltd.) Naoki Hirokawa (Hitachi-GE Nuclear Energy, Ltd.) Dennis Henneke (GE Hitachi Nuclear Energy) AE-OG-5927 Rev.0

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Hitachi-GE Nuclear Energy, Ltd. Proprietary Information

IAEA International Conference on Topical Issues in Nuclear Installation Safety: Safety

Demonstration of Advanced Water Cooled Nuclear Power Plants Vienna, Austria, 6–9 June 2017

RISK-INFORMED DESIGN FOR UK ABWR PROJECT

Yuki Ishiwatari (Hitachi-GE Nuclear Energy, Ltd.)

Kohei Hisamochi (Hitachi-GE Nuclear Energy, Ltd.)

Naoki Hirokawa (Hitachi-GE Nuclear Energy, Ltd.)

Dennis Henneke (GE Hitachi Nuclear Energy)

AE-OG-5927 Rev.0

Hitachi-GE Nuclear Energy, Ltd. Proprietary Information

Contents

1

1. Introduction

2. Scope of UK ABWR PSA in GDA

3. Peer Review

4. Risk-informed Improvements

5. Use of PSA to Support Design Optioneering

6. Summary

Hitachi-GE Nuclear Energy, Ltd. Proprietary Information

1. Introduction

22

PO

WER

10,000

15,000

(MWe)

1970 1975 19850

5,000

1995 2005

460460

540

784

1100

840

1100

1100

1100

820

1100

540

1137

1100

1356

1356

20,000

825

1380

1358

Advanced BWR phaseImprovement and Standardization phase

Domestic Production Phase

KASHIWAZAKI-KARIWA 7*

KASHIWAZAKI-KARIWA 6*

KASHIWAZAKI-KARIWA 4

HAMAOKA - 4*SHIKA - 1

KASHIWAZAKI-KARIWA - 5

SHIMANE - 2

HAMAOKA - 3*

FUKUSHIMA II - 4

FUKUSHIMA II - 2

HAMAOKA - 2*

TOKAI - 2*

FUKUSHIMA I-4HAMAOKA - 1*

SHIMANE – 1

(First Made-in-Japan NPP by Hitachi)

ONAGAWA - 3*

HAMAOKA - 5*

SHIKA - 2

1358SHIMANE - 3

2010

1373

OHMA – 1*1380

TSURUGA-1*

FUKUSHIMA I -1*

HD – 1*

NK – 1

1385

1373

MWe

357

Under constructionUnder construction

Under planning• 40 years continuous

construction and

maintenance

• 20 of 54 NPPs in

Japan by Hitachi-GE

(incl. cooperation

construction*)

Hitachi-GE Nuclear Energy, Ltd. Proprietary Information

1. Introduction

3

www.hitachi-hgne-uk-abwr.co.uk/downloads/2016-05_abwr-brochure.pdf

http://www.onr.org.uk/saps/saps2014.pdf

Hitachi-GE proposing to build ABWR plants in UK, based on experience of ABWRs in Japan and their design enhancements (i.e., Fukushima lessons)

Under Step 4 of Generic Design Assessment (GDA) and Generic Environment Permit (GEP)

UK regulatory expectation: Demonstrate ALARP(As Low As Reasonably Practicable)

Hitachi-GE Nuclear Energy, Ltd. Proprietary Information

1. Introduction

4

Hitachi-GE’s ALARP methodology

PSA has been used to support ALARP assessments

www.hitachi-hgne-uk-

abwr.co.uk/downloads/2015-10-30/UKABWR-

GA91-9101-0101-28000-RevB-PB.pdf

Hitachi-GE Nuclear Energy, Ltd. Proprietary Information

2. Scope of UK ABWR PSA in GDA

5

Numerical Tragers:

-

-

-(BSL)

(BSO)

Hitachi-GE Nuclear Energy, Ltd. Proprietary Information

1.0E-06

1.0E-05

1.0E-04

1.0E-03

1.0E-02

1.0E-01

1.0E+00

1.0E+01

1.0E-02 1.0E-01 1.0E+00 1.0E+01 1.0E+02 1.0E+03 1.0E+04

全予測頻度

(/年)

敷地外線量当量 (mSv)

BSL

BSO

2. Scope of UK ABWR PSA in GDA

6

Risk Targets:

- Offsite dose band frequencies

- Individual risk offsite

BSL: 1E-4/y, BSO: 1E-6/y

- Total risk of 100 or more fatalities

BSL: 1E-5/y, BSO: 1E-7/y

Intermediate measures for risk-informed improvements:

- Core Damage Frequency (CDF)

- Fuel Damage Frequency (FDF)

- Large Release Frequency (LRF)

- Large Early Release Frequency (LERF)

http://www.onr.org.uk/saps/saps2014.pdf

Dose [mSv]

Fre

q.

[/year]

Hitachi-GE Nuclear Energy, Ltd. Proprietary Information

2. Scope of UK ABWR PSA in GDA

7

SourceInternal events

Internalfire*

Internal flood*

Seismic*OtherIHs*

Other EHs*

Reactor(at Power) Detail assessment

Bounding assessment

Reactor(Shutdown)

Scoping Analysis

SFP

Fuel Route

Qualitative discussions to argue risk is insignificant

Turbinesystem

Simplified approach

(insignificantrisk)

Radwastesystem

* Retained after screening process in IAEA SSG-3

Hitachi-GE Nuclear Energy, Ltd. Proprietary Information

2. Scope of UK ABWR PSA in GDA

8

UK ABWR PSA was developed along with generic design development. Engineering teams in Hitachi-GE (as a plant vender) supported development/use of PSA.

PSA Support Team in Hitachi-GE

Systems

Design sections(Civil, Layout, Equipment)

C&I Electrical Fire assessment

Flooding assessment

Fragility analysis

Provide PSA input (design)- Design Information- FMEA- Capacity

Containment Performance

O&M

Design section(Civil, Layout, Equipment)

Provide PSA input (analysis)- Hazard- Fragility- Deterministic assessment

PSA Core Team

Hitachi-GE Nuclear Energy, Ltd. Proprietary Information

3. Peer Review

9

- Organized by GE-Hitachi

- Reviewed by industry experts from US and UK

- Similar process as performed in US (i.e., NEI 05-04)

- Covers Level 1~3 PSAs for all of the detailed/bounding assessments, as well as hazard screening process

- Reviewed against:

✓ UK Technical Assessment Guides

✓ ASME/ANS PRA Standards (including trial use or draft versions with provided feedback to ASME/ANS)

- Includes documentation of any peer review comments, as well as resulting responses

Hitachi-GE Nuclear Energy, Ltd. Proprietary Information

4. Risk-informed Improvements

10

ABWR Evolution through PSABWR

ABWR

ABWRs in Japan

UK ABWR (GDA)

- ECCS Configuration- ATWS countermeasure, etc.

- Alternate Water Injection/Spray- Hardened Containment Venting etc.

- LDF, COPS- Auto SLC, CTG, etc.

- Risk-Informed Design through Design changes and PSA development

- Examination on further design enhancementPSA developed

UK ABWR (Site Specific)

US ABWR

Hitachi-GE Nuclear Energy, Ltd. Proprietary Information

4. Risk-informed Improvements

11

During development of UK ABWR PSA

- PSA developed along with generic design development

- Design assumptions developed and recorded where necessary

- Design improvements / specific design options recommended from preliminary PSA results

- These recommendations implemented into PSA and recorded as design assumptions (where agreed with designer)

- Examples in next slide

Hitachi-GE Nuclear Energy, Ltd. Proprietary Information

4. Risk-informed Improvements

1212

During development of UK ABWR PSA

Incorporated in generic design

e.g., Backup room cooling system,Countermeasure against digital C&I CCF

e.g., Use of non-Class 1,2 systems as alternative injection measures

Options raised based on

preliminary PSA results

Basic requirements and high level design

Assumptions recorded and tracked

4. Risk-informed Improvements

e.g., Resonance frequency (seismic)Cable routing (fire)Component critical height (flood)

Way of dispassion depends on project schedule.

Hitachi-GE Nuclear Energy, Ltd. Proprietary Information

4. Risk-informed Improvements4. Risk-informed Improvements

13 Hitachi-GE Nuclear Energy, Ltd. Proprietary InformationHGNE COMMERCIAL

HGNE COMMERCIAL

5

Initial Identification of Options➢ Review of PSA results (MCS, Importance, low order

cutset, etc.)➢ Review of sensitivity analyses➢ Review of assumptions and uncertainties

Review with Engineering team➢ Generation of “Use of PSA” sheet➢ Review for additional options

Listing of options➢ Risk insights, design features and identified options

are put in the first table

Risk insightsIncorporated designOptions

Examination of further risk reduction➢ If the above criteria are met, the baseline option

should be selected over the alternate option.➢ If not, further assessment including identification of

implementation phase is considered.

Justification of BaselineAdditional assessmentImplementation Phase

FirstStep

Second Step

After development of

UK ABWR PSA

1. Identification of options

• Review of PSA results

• Review of sensitivity analysis

• Review of assumptions / uncertainties

• Review by designers

2. Examination of options

• Grossly disproportionate?

• Reasonably practical?

• Phase of implementation?

Hitachi-GE Nuclear Energy, Ltd. Proprietary Information

4. Risk-informed Improvements4. Risk-informed Improvements

14

After development of UK ABWR PSA

Example of options implemented / to be implemented

• Set performance objective of nitrogen leak rate from a Safety Relief Valves for long term operability

• Increase thickness of specific pipe segment to further reduce risk from ISLOCA

• Introduce measures to avoid initiating events caused by a human error (e.g., using interlocks)

• Apply fire rating to specific intra-divisional boundaries

• Improve seismic fragilities of specific components (as reasonably practicable) which were found to drive seismic risk

Hitachi-GE Nuclear Energy, Ltd. Proprietary Information 15

5. Use of PSA to Support Design Optioneering

PSA has been used to provide risk impacts from proposed design changes or justify baseline design

Examples:

• Category and Class

• Component location

• Surveillance interval

• Reactor depressurisation system design

• Severe accident countermeasures

Hitachi-GE Nuclear Energy, Ltd. Proprietary Information 16

6. Summary

• UK ABWR under GDA

• UK regulatory expectation: Demonstrate ALARP

• PSA as part of generic design process to support ALARP demonstration

• Full-scope PSA to compare with risk targets

• Use of peer reviews

• Risk-informed improvements during PSA development

• Systematic identification and examination of ALARP options based on developed PSA

• PSA also used to support design change decisions

Hitachi-GE Nuclear Energy, Ltd. Proprietary Information