The Experience of Risk Assessment and its Future ... · and its Future Utilization at Rokkasho...

JNFL1

The Experience of Risk Assessment and its Future Utilization at Rokkasho

Reprocessing Plant

Mr. Kazumi Takebe, Mr. Yoshikazu Tamauchi, Mr. Katsuyoshi Omori, Mr. Kunihiko Ogiya, Mr. Yoshiaki

Hayashi, and Dr. Shingo Matsuoka.

Safety Technology Office, Japan Nuclear Fuel Limited (JNFL).

October 16-18, 2007

JNFL2

Contents

Safety features of Rokkasho Reprocessing Plant (RRP)

Identification of events and PSA of RRP

An example of detailed PSA

Conclusion

Development and application of the Simplified PSA

Possible utilization of risk information

JNFL3

Shearing and Dissolution

Separation of Fission Products, U and Pu

Removing a Negligible Quantity

of FP

Purification

HALW*2

Vitrification

Uranium Denitration

Vitrificationand Package

Flow of U

Receiving & Storage of Spent Fuel

Cooling and Storage in the

Pool

Low Active Solid Waste Treatment

LALW*1

TreatmentAnalysis

DrumSample

Head-end

Removal of Nitric Acid and Making Product(Powder)

Flow of Pu

fuel

Separation

Control RoomEmergency

Power Supply

Uranium-Plutonium Co-denitration

Removal of Nitric Acid and Making Product(Powder)

Product Storage

*1LALW: Low Activite Liquid Waste*2HALW: High Activite Liquid Waste

Outline of Rokkasho Reprocessing Plant

JNFL4

Safety features of RRP

Safety features of RRP

Confinement ofRadioactive Materials

Radiation Shielding

Criticality Safety

A-seismic Design Decay HeatRemoval

Aircraft CrushProtection

Discharge Controlof Radioactive Effluents

Fire & ExplosionProtection

Multiple Protection Policy

JNFL5

Identification of events and PSA of RRP

Risk ProfileThe Risk Importance

Utilization of Risk Information

A Simplified PSA developed655 events to be assessed

Output

Detailed PSAHAZOP studyat basic design phase

AT: about 450 eventsBAT: about 600events

15 events selected

results incorporated

Detail design

3 events up-dated reflecting detail design

and operation procedure

JNFL6

An example of detailed PSA

Loss of Hydrogen Gas Scavenging Function in Plutonium Solution vessels

ref.4) Tamauchi, Y. et al., “Application of Probabilistic Safety Assessment to Rokkasho Reprocessing Plant (1); The Occurrence Frequency of Loss of H2 Scavenging Function in Pu Solution Vessel,” Nihon- Genshiryoku-Gakkai Shi ( J. At. Energy Soc. Jpn.), 4[5], 334-346 (2006), [in Japanese].

JNFL7

Outline of scavenging air supply system

Safety Compressed Air Supply System

Safety Compressor

Normal Compressed Air Supply System

Scavenging Air

Service Air

Pu Purification Facility

Vessel

PP

P

F

P:Pressure gaugeF:Flow meter

Schematic diagram of the scavenging air supply system

JNFL8

Accident scenarios and evaluation method

Failure of three safety compressors

Connecting Normal compressed air to the

safety scavenging system

Using service air supply system

Success

Keep scavenging air

Failure

Initiating Events (IE)

Safety functions

Leakage from piping or valves

Success Failure

Loss of hydrogen scavenging function

Accident frequency assessment ET/FT method

Failure rate of equipment Selected from Published literatures

Failure rate of air compressor, air operated valve, etc.:→referred from database of THORP and Tokai Reprocessing Plant

Human error probability THERP method

Evaluation Method and Database

JNFL9

Results of the assessment

Items Results

Summation of occurrence frequencies of IE

4x10-3 per year

Occurrence frequency of loss of hydrogen scavenging function

8x10-6 per year

Uncertainty of the frequency at 90% reliability level

1x10-6~2x10-5 per year

EF=4

Importance evaluation of each basic input events

Operator action of valve open for service air supply

Leakage from piping and valves

Operator action of valve open for normal compressed air supply

FV

RAW

JNFL10

Development and application of the Simplified PSA

ref.3) Tatsuo SHOUJI, Yuuji KOHATA, Kazumi TAKEBE, Yoshikazu TAMAUCHI, Kazuya

HAYASHI, Katsuya KUROSU, “A Study on Graded Approsch for Risk Assessment of the

Rokkasho Reprocessing Plant”, Paper No. 460, Proceedings of GLOBAL 2005, Tsukuba, Japan,

Oct. 9-13, 2005

JNFL11

Development of Simplified PSA

A Simplified PSA has been developed

Detailed PSA

FTA results of utility facilitiesHuman reliability Analysis, etc.

Results IncorporatedComparison of results of Simplified PSA and Detailed PSA Method

It can evaluate systematically evaluate the risk of RRPIt can evaluate the importance of systems, componentsand Human actionIt is possible to use the MS Excel sheet for all evaluationThe formula corresponding FTA are inputted in the sheet

JNFL12

Outline of simplified PSA procedure 1

Simplified PSA consist of several MS Excel sheet as follow,

Input sheets(a) Safety function/System Matrix(b) Utilities/Systems datasheet(c) Consequence evaluation sheet

Output sheets(d) Event tree display sheet for each event(e) Consequence evaluation result display sheet for each event(f) Importance evaluation result display sheet for each event (g) Risk of all events display sheet(h) Importance related to risk of reprocessing plant

JNFL13


Design information

Identification of hazards and accident sequences

Identification of safety functions

Identification of systems, components and human actions essential to the safety functions

Design and Operation Information input and summarized in (a) Safety function/System Matrix

JNFL14

C om ponent

Event

PS-1

-2

M S-1

-2

-3

-4

Failure rate M TTR Unavailability M TTR Failure rate UnavailabilityM S-1 M S-2 M S-3 M S-4 M S-5 (/h) (h) (/d) (h) (/h) (/d)

Activecom p.

Rem ote-operated valve for service air supply toPu concentrate vessel

○3.00E-03 0 3.00E-03

M anual-operated valve for norm al com pressed airsupply to safety com pressed air supply system

○ ○1.00E-04 0 1.00E-04

Passive Scavenging air supply line in Pu purification ○ ○ ○ 1.00E-08 24 9.59E-09 2.40E-07

com p. Service air supply line in Pu purification facility(piping & valves)

○

1.00E-08 24 9.59E-09 2.40E-07

Norm al com pressed air supply line to safetycom pressed air supply system (piping & valves)

○ ○1.00E-08 24 9.59E-09 2.40E-07

The value consideringtim e m argin

Function of on-dutyFunction of on-

dem and

Pu C oncentrate VesselLoss of H 2 scavenging function

The contents of safety functions

C ontinuous feeding of scavenging air from "Safety C om pressed AirSupply System "

Em ergency feeding of service air from "Safety C om pressed Air SupplySystem " by low w arning of flow rate

C om pressed air feeding from "Norm al C om pressed Air Supply System "by low alarm of pressure

Prevention

Tim e m argin（h)

1

Safety function

－

C om pressed air feeding from "Norm al C om pressed Air Supply System "by low w arning of flow rate

Loss ofscavengingfunction

Tim e tooperate(h)

start operation

Increasing ofH 2 density

Releasesequence


Excerpt from (a) Safety function/System Matrix

Input failure rates for system, component,

human action related to initiating event and

safety function

A list “Database of system, component and human action” have been set

conservatively based on the published documents. Human error rate was determined based on detailed PSA.

Markup components essential for safety

function

Describe Components , human actions relating toprevention systems and

safety functions

Enter the Safety functions

Enter the Prevention systems against the

accident

Input the component and kind of event for

evaluation

JNFL15


Num ber of system s

Num ber of needed system sof O n-duty equipm ent

Num ber of system s of O n-duty equipm ent

Num ber of needed system sof stand-by equipm ent

Num ber of system s ofstand-by equipm ent

failure rate（per system s）(/h)

M aintenance frequency ofO n-duty equipm ent (/yr)

M aintenance frequency ofstand-by equipm ent (/yr)

Test frequency of stand-byequipm ent （/yr）

m aintenance tim e(h)

M ean tim e to repair (h)

C C F factor2

Unavailability of signal andoperation,etc. related to thestand-by equipm ent start

failure rate (O n-duty)(/h)eff

unavailability of stand bysystem (O n-dem and)(/dem and)

Unabailability of thecom ponent considering thebackup, etc.

eff

Unavailability of redundant system

(b) Utilities/Systems datasheet

(a) Safety function/System Matrix

Analyst enters the operating information such as component type, redundancy, maintenance period and

test interval, etc.

Function of on-duty Function of on-dem and

failure rate M TTR Unavailability M TTR Failure rate Unavailability

(/h) (h) (/d) (h) (/h) (/d)

3.00E-03 0 3.00E-03

1.00E-04 0 1.00E-04

1.00E-08 24 9.59E-09 2.40E-07

1.00E-08 24 9.59E-09 2.40E-07

1.00E-08 24 9.59E-09 2.40E-07

1.00E-01 0 1.00E-01

1.00E-07 24 9.59E-08 2.40E-06

1.00E-04 0 1.00E-04

1.00E-07 24 9.59E-08 2.40E-06

1.00E-04 0 1.00E-04

1.00E-03 0 1.00E-03

1.00E-03 0 1.00E-03

1.00E-03 0 1.00E-03

1.00E-04 0 1.00E-04

1.00E-02 0 1.00E-02

Relation of initiating events and detection

○

○ ○

○ ○

○ ○


System s, com ponents and hum an actionsrelated to safety functions

Action of valve open for norm al com pressed air supply tosafety com pressed air supply system

Perception of loss of scavenging air through flow rate lowalarm

Action of valve open for service air supply to Puconcentrate vesselPerception of failure of safety com pressed air supplysystem through pressure low alarm

Pressure m eter for scavenging air in safety com pressedair supply system (two-redundant system )

Low alarm of pressure of scavenging air in safetycom pressed air supply system (two-redundant system )

Flow m eter for scavenging air to Pu concentrate vessel（installed for each vessel）

Low alarm of flow rate of scavenging air to Puconcentrate vessel（installed for each vessel）

Service air supply line in Pu purification facility (piping &valves)

Norm al com pressed air supply line to safety com pressedair supply system (piping & valves)

Scavenging air supply line in Pu purification facility(piping & valves)

Rem ote-operated valve for service air supply to Puconcentrate vesselM anual-operated valve for norm al com pressed air supplyto safety com pressed air supply system

Initiating events(Failure of individualsystem s below)

Scavenging air supply line in Pu purification facility (piping & valves)

Safety cooling water supply system

Safety com pressed air supply system

Em argency electric supply system

Low alarm of flow rate ofscavenging air to Pu concentratevessel（installed for each vessel）

Low alarm of pressure ofscavenging air in safetycom pressed air supply system(two-redundant system )

Calculated result is entered

C om ponent

Event

PS-1

-2

M S-1

-2

-3

-4

M S-1 M S-2 M S-3 M S-4 M S-5

Activecom p.


○


○ ○

Passive Scavenging air supply line in Pu purification ○ ○ ○com p. Service air supply line in Pu purification facility

(piping & valves)○


○ ○

I&C Flow m eter for scavenging air to Pu concentrate vessel（installedfor each vessel）

○ ○

Low alarm of flow rate of scavenging air to Pu concentrate vessel（installed for each vessel）

◎ ◎

Pressure m eter for scavenging air in safety com pressed air supplysystem (tw o-redundant system )

○

Low alarm of pressure of scavenging air in safety com pressed airsupply system (tw o-redundant system )

◎

Perception of loss of scavenging air through flow rate low alarm ○

Action of valve open for service air supply to Pu concentratevessel

○

Perception of failure of safety com pressed air supply systemthrough pressure low alarm

○ ○

Action of valve open for norm al com pressed air supply to safetycom pressed air supply system

○ ○

Norm al cooling water supply systemNorm al cooling water supply system for F facilitybackup cooling water supply systemSafety cooling water supply systemSafety cooling water supply system for F facilitygeneral cooling water supply system 1general cooling water supply system 2Norm al/buckup com pressed air supply systemSafety com pressed air supply systemNorm al steam supply system

Norm al electric supply system Backup electric supply system Em argency electric supply system Em argency electric supply system for F facility




Em ergency feeding of service air from "Safety C om pressed Air SupplySystem " by low warning of flow rate


electricsystem

supportsystem

Prevention

Hum anaction

Tim e m argin（h)

1

Safety function

－

C om pressed air feeding from "Norm al C om pressed Air Supply System "by low warning of flow rate


Tim e tooperate(h)

start operation


Releasesequence

JNFL16

Norm al cooling water supply systemNorm al cooling water supply system for F facilitybackup cooling water supply systemSafety cooling water supply systemSafety cooling water supply system for F facilityG eneral cooling water supply system 1G eneral cooling water supply system 2Norm al/buckup com pressed air supply systemSafety com pressed air supply systemNorm al steam supply system


Electricsystem

System s, com ponents and hum an actions related to safetyfunctions

Prevention Safety function

Supportsystem


Excerpt from (a) Safety function/System Matrix

Unavailability of such support systems as utilities, which related to many events, has been set in (a), with simplified

fault tree equation based on detailed PSA results.

. Therefore, analysts should select the support system

essential to the safety functions and mark the symbols

JNFL17


occurrencefrecency(1/y)

Dose (m Sv)

Risk(death/

y)

S 0.0E+00 0 0.0E+00

［PS-1]

S 8.4E-05 0 0.0E+00

F

S 7.7E-05 0 0.0E+00

F

S Pu conc. solution 3.8E-06 0 0.0E+00

［PS-2] 1.5m 3

F

S Pu conc. solution 0.0E+00 2.3E-02 0.0E+00

1.5m 3

F

Pu conc. solution 0.0E+00 5.0E+00 0.0E+00F 1.5m 3

total0.0E+00

Increasing ofH2 density

－


Loss ofscavengingfanction

O ccurance ofabnorm alcondition

Loss ofpreventionsystem s

Safety functions

Releasesequense

M S-3 M S-4 M S-5


M S-1 M S-2Sourse team

Em ergencyfeeding ofservice airfrom "SafetyC om pressedAir SupplySystem " bylow warningof flow rate

C om pressedair feedingfrom"Norm alC om pressedAir SupplySystem " bylow alarm ofpressure

C om pressedair feedingfrom"Norm alC om pressedAir SupplySystem " bylow warningof flow rate

Theam ount ofm aterial

1.6E-04(/y) 1.0E+00(/d) 4.9E-01(/d) 4.7E-02(/d)

C ontinuousfeeding ofscavenging airfrom "SafetyC om pressed AirSupply System "

Running macro program

(a) Safety function/System Matrix

Calculated occurrence frequency is automatically

shown in form of ET (d)

Function of on-duty Function of on-dem and

failure rate M TTR Unavailability M TTR Failure rate Unavailability

(/h) (h) (/d) (h) (/h) (/d)

3.00E-03 0 3.00E-03

1.00E-04 0 1.00E-04

1.00E-08 24 9.59E-09 2.40E-07

1.00E-08 24 9.59E-09 2.40E-07

1.00E-08 24 9.59E-09 2.40E-07

1.00E-01 0 1.00E-01

1.00E-07 24 9.59E-08 2.40E-06

1.00E-04 0 1.00E-04

1.00E-07 24 9.59E-08 2.40E-06

1.00E-04 0 1.00E-04

1.00E-03 0 1.00E-03

1.00E-03 0 1.00E-03

1.00E-03 0 1.00E-03

1.00E-04 0 1.00E-04

1.00E-02 0 1.00E-02

Relation of initiating events and detection

○

○ ○

○ ○

○ ○


System s, com ponents and hum an actionsrelated to safety functions

Action of valve open for norm al com pressed air supply tosafety com pressed air supply system

Perception of loss of scavenging air through flow rate lowalarm

Action of valve open for service air supply to Puconcentrate vesselPerception of failure of safety com pressed air supplysystem through pressure low alarm

Pressure m eter for scavenging air in safety com pressedair supply system (two-redundant system )

Low alarm of pressure of scavenging air in safetycom pressed air supply system (tw o-redundant system )

Flow m eter for scavenging air to Pu concentrate vessel（installed for each vessel）

Low alarm of flow rate of scavenging air to Puconcentrate vessel（installed for each vessel）

Service air supply line in Pu purification facility (piping &valves)

Norm al com pressed air supply line to safety com pressedair supply system (piping & valves)

Scavenging air supply line in Pu purification facility(piping & valves)

Rem ote-operated valve for service air supply to Puconcentrate vesselM anual-operated valve for norm al com pressed air supplyto safety com pressed air supply system

Initiating events(Failure of individualsystem s below)

Scavenging air supply line in Pu purification facility (piping & valves)

Safety cooling w ater supply system

Safety com pressed air supply system

Em argency electric supply system

Low alarm of flow rate ofscavenging air to Pu concentratevessel（installed for each vessel）

Low alarm of pressure ofscavenging air in safetycom pressed air supply system(two-redundant system )

Input relation of initiating events and detection

C om ponent

Event

PS-1

-2

M S-1

-2

-3

-4

M S-1 M S-2 M S-3 M S-4 M S-5

Activecom p.


○


○ ○

Passive Scavenging air supply line in Pu purification ○ ○ ○com p. Service air supply line in Pu purification facility

(piping & valves)○


○ ○

I&C Flow m eter for scavenging air to Pu concentrate vessel（installedfor each vessel）

○ ○

Low alarm of flow rate of scavenging air to Pu concentrate vessel（installed for each vessel）

◎ ◎

Pressure m eter for scavenging air in safety com pressed air supplysystem (tw o-redundant system )

○

Low alarm of pressure of scavenging air in safety com pressed airsupply system (tw o-redundant system )

◎

Perception of loss of scavenging air through flow rate low alarm ○

Action of valve open for service air supply to Pu concentratevessel

○

Perception of failure of safety com pressed air supply systemthrough pressure low alarm

○ ○

Action of valve open for norm al com pressed air supply to safetycom pressed air supply system

○ ○

Norm al cooling water supply systemNorm al cooling water supply system for F facilitybackup cooling water supply systemSafety cooling water supply systemSafety cooling water supply system for F facilitygeneral cooling water supply system 1general cooling water supply system 2Norm al/buckup com pressed air supply systemSafety com pressed air supply systemNorm al steam supply system





Em ergency feeding of service air from "Safety C om pressed Air SupplySystem " by low warning of flow rate


electricsystem

supportsystem

Prevention

Hum anaction

Tim e m argin（h)

1

Safety function

－

C om pressed air feeding from "Norm al C om pressed Air Supply System "by low warning of flow rate


Tim e tooperate(h)

start operation


Releasesequence

Input time margin to accident

occurrence from initiating event

JNFL18


In the simplified PSA, consequence is represented as radiation dose to the publicThe radiation dose is calculated in (c) Consequence evaluation sheet The result is showed on (e) Consequence evaluation result display sheet based on five-factors formula *

*ref.7) Nuclear Fuel Cycle Facility Accident Analysis Handbook, NUREG/CR-6410, (1998).

ST = MAR*DR*ARF*RF*LPFDi=ST*R*X/Q*H

Quantification of consequence

Where,MAR:Material At RiskDR:Damage RatioARF:Airborne Release FractionRF:Respirable FractionLPF: Leak path Factor

ST:Source TeamDi:Effective Dose due to inhalation R:Inhalation ratioX/Q:Relative concentrationH:Coefficient for ingestion and inhalation

JNFL19


(e) Consequence evaluation result display sheet for each event

occurrencefrecency(1/y)

Dose (m Sv)

Risk(death/

y)

S 0.0E+00 0 0.0E+00

［PS-1]

S 8.4E-05 0 0.0E+00

F

S 7.7E-05 0 0.0E+00

F

S Pu conc. solution 3.8E-06 0 0.0E+00

［PS-2] 1.5m 3

F

S Pu conc. solution 0.0E+00 2.3E-02 0.0E+00

1.5m 3

F

Pu conc. solution 0.0E+00 5.0E+00 0.0E+00F 1.5m 3

total0.0E+00


－


Loss ofscavengingfanction

O ccurance ofabnorm alcondition

Loss ofpreventionsystem s

Safety functions

Releasesequense

M S-3 M S-4 M S-5


M S-1 M S-2Sourse team

Em ergencyfeeding ofservice airfrom "SafetyC om pressedAir SupplySystem " bylow warningof flow rate

C om pressedair feedingfrom"Norm alC om pressedAir SupplySystem " bylow alarm ofpressure

C om pressedair feedingfrom"Norm alC om pressedAir SupplySystem " bylow warningof flow rate

Theam ount ofm aterial

1.6E-04(/y) 1.0E+00(/d) 4.9E-01(/d) 4.7E-02(/d)

C ontinuousfeeding ofscavenging airfrom "SafetyC om pressed AirSupply System "

(d) Event tree display sheet for each event

Consequence evaluation result Risk of each accident scenarios

Running macro

Running macro

C om p.Pu C oncentrate VesselEvent Loss of H2 scavenging fanction 9.9E-11 (death/y)

Risk and increasm ent of risk （death/y)System s, com ponents and hum an actionsrelated to safety functions

Rem ote-operated valve for service air supply to Pu concentrate vessel 9.2E-11 2.3E-09 6.7E-02 2.3E+01M anual-operated valve for norm al com pressed air supply to safety com pressed airsupply system

9.8E-11 2.1E-09 2.0E-03 2.1E+01

Scavenging air supply line in Pu purification facility (piping & valves) 8.7E-11 1.1E-01Service air supply line in Pu purification facility (piping & valves) 9.9E-11 5.3E-06

Norm al com pressed air supply line to safety com pressed air supply system (piping& valves)

9.9E-11 4.9E-064.3E-12 9.5E-10 9.6E-01 9.6E+00

FV

Risk

RAWR(A=0) R(A=1)

(f) Importance evaluation result display sheet for each event

JNFL20


(g) Risk of all events display sheet

1.E-05

1.E-03

1.E-01

1.E+01

1.E+03

Occurrence frequency (/yr)

Conse

quence

(m

Sv)

(h) Importance related to risk of reprocessing

plant.

FV index

RAW

1.E+00

1.E+01

1.E+02

1.E+03

1.E+04

1.E+05

1.E+001.E-051.E-10

JNFL21

Comparison of the Results of it and Detailed PSA

Leakage of pipingor valves in Pu facility

1%

Stop of 3 units of compressors3%

Leakage of piping orvalves in safety airsupply system 73%

22%

8E-6/y

Leakage of pipingor valves in Pu facility

Leakage of piping of valves in denitration

facility 3%

Stop of 3 units ofcompressors 3%

Leakage of piping orvalves in safety airsupply system 57%

37%

2E-5/y

Results of detailed PSA methodResults of Simplified PSA method

Leakage of piping of valves in denitration facility

The frequency calculated by the simplified PSA method well agrees with the result of detailed PSA with the reliability of 90%

JNFL22

Possible utilization of risk information

JNFL23

A risk profile

An example of risk profile dotted according to the calculated results as of September 2007

1.E-06

1.E-05

1.E-04

1.E-03

1.E-02

1.E-01

1.E+00

1.E+01

1.E+02

1.E+03

1.E-10 1.E-08 1.E-06 1.E-04 1.E-02 1.E+00

Occurrence frequency (/yr)

Conse

quence

(m

Sv)

JNFL24

Risk importance for each components

An example of risk importance dotted according to the calculated results as of September 2007

FV index

RAW

1.E+00

1.E+01

1.E+02

1.E+03

1.E+04

1.E+05

1.E+001.E-051.E-10

JNFL25

Utilizing the risk information- future plan

Risk profile in 2 years

Classification of components and systems into three classes of risk importance

Determination of allowable outage time (AOT), examination of on-line maintenance and inspection period

“Residual risk” and seismic PSA

JNFL26

Mt.Fuji and Mts.Hakkouda 3776m

<1600m

The Experience of Risk Assessment and its Future ... · and its Future Utilization at Rokkasho...

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Transcript of The Experience of Risk Assessment and its Future ... · and its Future Utilization at Rokkasho...