048 kamran presentation.ppt - international atomic … · •recommendations and explanations for...

PNRA REGULATORY OVERSIGHT TO AGEING MANAGEMENT AND

RESIDUAL LIFE ASSESSMENT FOR LONG-TERM OPERATION OF

NPPs

Fourth International Conference on Nuclear Power Plant Life Management

Lyon, France 23–27 October, 2017

KAMRAN Mansoor

PAKISTAN NUCLEAR REGULATORY AUTHORITYIslamabad, Pakistan

(www.pnra.org)

PRESENTATION LAYOUT

� Introduction

� NPPs Profile of Pakistan

� PNRA Regulatory Framework

� Regulations encompassing Ageing Management and Operation Beyond Design Life requirements

� Overview of AM and LTO by PNRA

� PSR and Time Limited Ageing Analysis (TLAA)

� Conclusion

2

INTRODUCTION

� Implementation of the effective ageing management is one

of the regulatory approach leading to safe and long term

operation (LTO) of Nuclear Power Plants.

� PNRA Regulations and IAEA Safety Standards describe

the requirements for licensing beyond design life. This

include; plant assessment focusing ageing management

and validation of time-limited ageing analysis (TLAAs) or

residual life assessment (RLA).

� K-1 (PHWR) is operating beyond design life after

comprehensive safety evaluation for long term operation.

3

INTRODUCTION

� Periodic Safety Review (PSR) is a pre-requisite

for revalidation of operating licence which is

considered for 10 years interval. Review,

validation and RLA cover the safety related

structure, systems and components (SSCs).

� The presentation describes the regulatory

oversight regarding assessment to ensure

safety during design and beyond design life of

NPPs in Pakistan.

4

NPPs PROFILE

K-1:

� PHWR

� Designed Electrical Power: 137 MWe

� Commercially operating since 1972

� Design life: 30 years

� Re-licensed for further operation

Chashma NPP Unit-1 (C-1):

� PWR


� Started commercial operation in 2000


� Operating license renewed after PSR in

2010 for another 10 years5

NPPs PROFILE

Chashma NPP Unit-2 (C-2):

� PWR


� Started commercial operation in 2011


� Validity of operating license till 2021

� Chashma Unit-3 & 4 (C-3 & C-4); 340 MWe: PWR; Construction started in 2011:

Both units are under trial operation and operating license is expected by 2018

� (K-2/K-3); 1100 MWe: PWR; construction started in August and November, 2015:

Operating licence expected by 2020 & 2021 respectively.

6

PNRA REGULATORY FRAMEWORK

•Issued by the Government of Pakistan

•Presents basic objectives, concepts and principles of nuclear and radiation safety and protection for the regulation of nuclear energy

Ordinance

•Issued by PNRA; Administrative & Technical

•Specify the basic requirements that must be fulfilled to ensure safety

Regulations

•Issued by PNRA, of a non-mandatory nature

•Recommendations and explanations for meeting regulatory requirements

Regulatory Guides

Codes and Standards

•Issued by national and international organizations e.g. IEEE, ASME etc.

•Recommend standard set of criteria or acceptance values 7

PNRA REGULATIONS ENCOMPASSING AGEING

MANAGEMENT AND OPERATION BEYOND DESIGN LIFE

REQUIREMENTS

Regulations on the Safety of NPP –

Operation (PAK/913)

Regulations for the Safety of NPP –

Design (PAK/911)

Regulations for Licensing of

Nuclear Installations

(PAK/909)

Address the requirements for

ageing management and

operation beyond design life

for nuclear power plants in

Pakistan.

Moreover, for regulatory

decision making for LTO, the

international practices and the

guidance provided in IAEA

safety standards are also used

8

PNRA Regulations on the Licensing of Nuclear

Installations- PAK/909

� PNRA Regulations on the Licensing of Nuclear Installations - PAK/909

describe licensing process at different stages of licensing & authorizations

for nuclear installations.

� PAK/909 also defines the requirements for licensing beyond design life.

� These include that in case the licensee intends to operate the nuclear

installation beyond its design life, licensee may apply at least three (03)

years before the end of design life along-with the documents listed below:

1. Latest report of Periodic Safety Review (PSR).

2. Updates of all following documents:

i. Final Safety Analysis Report (FSAR);

ii. Probabilistic Safety Analysis (PSA) Level-I;

iii. Physical Protection Program;

iv. Emergency Preparedness Plans;

v. Radiation Protection Program; 9

PNRA Regulations on the Licensing of Nuclear Installations- PAK/909

vi. Environmental Monitoring Program;

vii. Radioactive Waste Management Program;

viii. Initial Decommissioning Plan;

ix. Pre-Service Inspection/In-Service Inspection Program;

x. Quality Assurance Program for Operation;

� In addition, the following documents shall also be submitted along-with the

application for reference and record:

- Programs for maintenance, testing, surveillance and inspection of

structures, systems and components important to safety;

- Fire Protection Program.

� On approval of documents mentioned at S. No. 1 & 2, PNRA may grant

license to operate the nuclear installation beyond its design life for the

duration requested in the application or as determined by the Authority.

10

Regulations for the Safety of NPP- Design

(PAK/911)

� Licensee should provide appropriate margins in the design

for all structures, systems and components important to

safety so as to take into account relevant ageing and wear-

out mechanisms and potential age related degradation, in

order to ensure the capability of the structure, system or

component to perform the necessary safety function

throughout its design life.

� Provisions are to be considered for monitoring, testing,

sampling, and inspection, to assess aging mechanisms

predicted at the design stage and to identify unanticipated

behavior or degradation that may occur in service.

11

� PAK/913 establishes requirements for Ageing Management

during the operation phase through PSR which is normally

conducted after every ten years of interval. PSR determines

that to what extent the existing safety analysis remains

valid.

� PSR takes into account safety factors like; plant design,

actual conditions of systems, structures and components,

equipment qualification, ageing, deterministic safety

analysis, probabilistic safety analysis, etc.

� Licensee develop the AMPs to meet the regulatory

requirements which are established in regulations. PNRA

ensures its availability and implementation during plant

operation phase.

PNRA Regulations on the Safety of NPP – Operation

(PAK/913)

12

� PNRA has included different regulatory requirements in

revision of PNRA Regulations PAK/913 in the light of

IAEA Safety Standards Series No. SSR-2/2 on safety of

NPPs during commissioning and operation (i.e.

licensee to ensure implementation of AMPs, define the

long term effects arising from operational and

environmental conditions, determine consequences of

ageing and activities necessary to maintain operability

of SSCs, etc.)

Regulations on the Safety of NPP – Operation

(PAK/913)

13

� PNRA regional offices at sites verify the regulatory

requirements of plant operation, maintenance, testing,

surveillance, in-service inspections, ageing

management, adherence to operational limits and

conditions (OLC) and procedures.

� In case of PSR, coordination is carried out at HQ

level, however, its implementation is verified and

checked by RNSDs.

� PNRA has so far conducted PSR of two operating

nuclear power plants i.e. C-1 and K-1.

OVER VIEW OF AGEING AMANGEMENT FOR

LONGTERM OPERATION of NPPs

14

CONDUCT OF PSR

� Review strategy for PSR was based on IAEA Safety Guide NS-G-2.10. For

the upcoming PSRs, SSG-25 will be followed.

� Review of PSR included; preparation & approval of PSR strategy,

submission and review of PSR reports, identification of issues and

preparation of corrective action program followed by implementation and

verification of corrective actions.

� During PSRs, the safety factor of ageing management and condition of

SSCs of plants got special attention by both the Regulator and the

Operators.The different aspects of ageing management were verified during

review of Safety Factor 4 (Ageing).

� These include: programme policy, AMP organization and resources, criteria

for identifying SSCs, records that provide information in support of the

management of ageing, evaluation of potential ageing degradation that may

affect the safety functions of SSCs e.g. fatigue, corrosion, erosion, flow

accelerated corrosion (FAC), wear, thermal embrittlement, irradiation

embrittlement, vibration etc. 15

PSR Review Strategy

Preparation of PSR

Plan/Strategy for PNRA

Approval

Plan Approval by

PNRA

Preparations

Reviews

Corrective Actions Program

Review Reports

Identification of Corrective

Actions

PNRA Reviews

PSR Approval

Corrective Actions

Implementation

16

IMPROVEMENTS AS A RESULT OF PSR

� In case of C-1, improvements made included; removal of

inconsistency of documentation, development of the

control leakage program of SRC, development of Ageing

Management Programs (i.e. RPV, RCP, SGs, PZR,

CRDM, containment, Spent Fuel Storage Pool, cables

etc.), Reanalysis of accidents as presented in FSAR etc.

� In case of K-1 , AMPs of major components were verified.

SSCs are properly managed against corrosion, normal

wear and tear or what we call ageing. All SSCs are being

taken care with special emphasis on the critical SSCs.

� Accordingly, PNRA accepted PSR after submission of

corrective actions program by licensee as per PSR

review strategy. 17

Time Limited Ageing Analysis (TLAA) of K-1

� PNRA required licensee to justify safe operation,

especially the critical SSCs like;

Fuel channels,

Feeder pipes,

Steam generators,

Civil structures etc.

� Licensee carried out the TLAAs study of critical SSCs

based on IAEA International Generic Ageing Lessons

Learned (IGALL) SRS-82 and TECDOC 1736

guidelines.

18

Time Limited Ageing Analysis (TLAA) of K-1 :

FUEL CHANNELS

� K-1 reactor fuel channels have been inspected as

per CSA Standard N285.4 to evaluate the

degradation mechanisms including; pressure tube

to Calandria tube contact and debris and bearing

pad fretting flaws.

� CANDU Energy (CE) performed core assessment

to demonstrate compliance with the technical

requirements of CSA N285.8 to justify the continued

safe operation.

� As per assessment, K-1 is safe to operate beyond

design life up to the evaluation period.

19


FEEDER PIPES

� Stress Analysis of feeder pipes is completed to evaluate

minimum acceptable wall loss thickness as per

requirements of CSA N285.4;

� M/s AMECC NSS Canada performed assessment to verify

Minimum Allowable Wall Loss Thickness (MAWT) values

for each individual feeders at the first elbow downstream

of feeder grayloc couplings as well as the bounding MAWT

values for entire feeder length as per requirements of the

CSA Standard N285.4-09 and ASME B&PV NB-3600

� Inspection results and subsequent analysis have shown

that the thinning rate is well below the allowable limits

(MAWT) and K-1 is safe to operate beyond design life up

to the evaluation period.20


STEAM GENERATORS

� Water lancing campaigns have already been

completed to remove the sludge to improve the

healthiness of steam generator tubes – Next

campaign is planned in 2017-18.

� Condition Assessment Report of CANDU

Energy included; thermal hydraulics analysis,

flow induced vibration analysis, destructive and

non-destructive examinations to verify overall

assessment of any degradation.

� Tube plugging criteria was also considered for

further safe operation.21


STEAM GENERATORS

� Further, following mitigatory and corrective

measures were taken:

Periodic inspections,

leaked tube plugging,

chemistry control,

continuous blow down,

condenser tube plugging, etc.

� K-1 has taken all above mentioned measures and

it is evaluated that K-1 SGs are safe to operate

beyond design life up to the evaluation period.22

Time Limited Ageing Analysis (TLAA) of K-1 : CIVIL

STRUCTURES

� TLAA of containment was carried out in the light of guide

lines:

TLAA301 on concrete containment tendon pre-stress

and pump house/intake bay and

TLAA302 on effects of creep and shrinkage on

performance of concrete structures.

These analysis supported containment and pump

house integrity for the intended extension period.

� K-1 has fulfilled the regulatory requirements to the

satisfaction of PNRA, therefore, K-1 OL was extended

beyond design life.

23

CONCLUSION

� PNRA has established requirements for ageing

management of nuclear power plants during design

and operation phases. Further, PNRA regulations

explicitly provide requirements for operation beyond

design life of nuclear power plants.

� Plant ageing during design life and beyond design life

is being maintained by the licensees and PNRA is

effectively reviewing and monitoring the issues related

to structures, systems & components (SSCs)

condition and ageing of nuclear power plants

according to the regulatory requirements.

24

THANKS

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