Status of Ignalina's Safety Analyses Reports

Dr. Habil. E. Uspuras

Laboratory of Nuclear Installation Safety

Lithuanian Energy Institute

3 Breslaujos

3035 Kaunas

Lithuania

 

 

 

International Conference on the Strengthening of Nuclear Safety in Eastern Europe, Vienna, 14-18 June 1999

 

OUTLINE

  1. Introduction: A Historical Contexts
  2. Safety Justification Report of the Ignalina NPP (TOB)
  3. "In-Depth Safety Assessment of the Ignalina NPP" Project
  4. Recommendations of the Ignalina Safety Panel
  5. Follow-up Safety Analyses of the Ignalina NPP
  6. Ignalina PSA Level 1 Project
  7. Conclusions

 

Introduction: A Historical Contexts

 

Safety Justification Report (TOB)

 

In-Depth Safety Assessment Project (1)

 

In-Depth Safety Assessment Project (2)

The objectives of the SAR were:

 

In-Depth Safety Assessment Project (3)

The SAR project was organised in 10 Task Groups and the RSR structure reflected this. The groups were:

TG1 Plant Description

TG2 History of Safety and Performance

TG3 Fault Schedule

TG4 System Analysis

TG5 Accident Analysis

TG6 Equipment Qualification

TG7 Management of Ageing

TG8 Role of Operator

TG9 Safety Management

TG10 Demonstration of Acceptability

 

Fault Schedule (TG3)

Accidents Initiated by Equipment Failure

 

Loss of Coolant Accidents (1)

 

Loss of Coolant Accidents (2)

The SAR analyses of LOCAs revealed several plant deficiencies. Some Plant Modifications are required:

Further analysis is required to support the proposed hardware installations and to resolve critical issues.

 

Multiple Pressure Tube Ruptures Issue

Recommendations on the safety Improvements at the Ignalina NPP concerning MPTR issue:

Further analysis is required to support the proposed hardware installations and to resolve MPTR critical issues.

 

Reactivity Initiated Accidents

Major Issue

Further analysis is required.

 

Steam Line Failures

The SAR analysts propose a number of hardware modifications and changes in regulations and procedures to overcome the design weaknesses and to better protect the surrounding population against radiological exposures after Steam Line rupture events, first of all

Further analysis is required to support the proposed hardware installations and to resolve critical issues.

 

Anticipated Transients Without Scram

 

ATWS (2)

 

Major Safety Issues Originated from SAR

  1. Second Shutdown System
  2. CPS compensatory measures
  3. Reactor scram and ECCS actuation on low flow in one GDH
  4. Reactor scram and ECCS actuation on dP/dt signal in drum separator
  5. ALS Safety Case
  6. RCS Safety Case
  7. Additional Accident Analysis
  8. Safety analyses for core with new fuel design

 

Follow-up Safety Analyses

 

DAZ Project (1)

 

DAZ Project (2)

 

 

 

Loss of off-site power supply with failure of existing Control and Protection System and activation of DAZ system. Pressure in the main circulation circuit

 

 

Local flow stagnation accidents

 

 

Local flow stagnation accidents (Cont.)

 

 

 

 

 

Flow rate in the maximum loaded channel connected to the

accidental GDH in case of early ECCS initiation

 

 

 

 

 

 

Peak fuel cladding temperatures in the maximum loaded channel

connected to the accidental GDH in case of early ECCS initiation

 

 

 

 

 

 

 

 

Peak pressure tube wall temperatures in the maximum loaded channel

connected to the accidental GDH in case of early ECCS initiation

 

Conclusions on local flow stagnation accidents

 

ALS Safety Case

 

RCS Safety Case

 

The Barselina Project

 

Scope of the PSA Study

 

Applications

 

Results

Core Damage Frequencies for IE Groups

AS

AI

AL

DS

DI

DL

LOCA Z1

9,12E-08

8,04E-09

1,05E-09

4,54E-10

1,85E-07

3,80E-10

LOCA-Z2

2,15E-08

3,46E-09

2,03E-09

 

7,38E-10

 

LOCA-Z3

2,06E-09

2,58E-11

7,82E-11

 

 

 

LOCA-Z4

6,34E-08

7,42E-09

1,63E-09

 

1,55E-12

 

LOCA (total)

1,78E-07

1,89E-08

4,79E-09

4,54E-10

1,86E-07

3,80E-10

Area Events

 

1,34E-09

4,60E-07

 

 

 

Blockages

1,61E-07

8,46E-13

5,94E-09

 

 

 

Transients

4,79E-07

1,47E-08

1,97E-06

 

 

 

Total

8,18E-07

3,50E-08

2,44E-06

4,54E-10

1,86E-07

3,80E-10

Total A+D 3,48E-06

 

Conclusions