HRA and FLEX
George Apostolakis
Head, Nuclear Risk Research Center
apostola@mit.edu
http://criepi.denken.or.jp/en/nrrc/index.html
Presented at theRegulatory Information Conference
Session W27: Recent Developments inRealistically Modeling FLEX Equipment in
PRA and Incorporating FLEX Insights into
Decision-making
March 13, 2019111

NRRC HRA Guide Overview
Step6

Quantification method(HRA Calculator, etc.)

Quantify HEP
Modeling of Cognitive / Diagnostic
Failures

Modeling of Execution Failures
and Recovery

Step5

Step7

Narrative Documentation( Results of interview questions list, etc., )Qualitative Analysis
Narrative Development

Step4

Cognition

Step4- Context of the cognitive process- Time window and event progress- PSF (Decision tree)

Execution- PSF (Operations/Executions)- Stress factors（environment, Margin
time/Acceptable diagnostic time, etc.,）

Step3

General questions on
cognitive context

HRA Team discussions(including operator Interviews)

Step1

General questions onexecution
Step2

Define PRA scenario
Collection of information

Identification of key tasks(Preliminary CRT)
22

Utilization of Interview Results
Narrative
1. Informationfrom theprocedures

2. Observations of the control
room simulator training

3. Interview with operators

No.

Hearing items (Input items related to HRA Calculator)

13

When the cue necessary for implementing the applicable operation is given
to the operators, is the workload on the operators high or is there
confusion? (High workload or confusion decreases the operator
attentiveness (oversight in verifying necessary information))‐‐

Roles are clearly specified, so there isno confusion.
There is no confusion even during thefirst accident alarm.

14

Is it enough to verify the parameters necessary for implementing theapplicable operations once, or must the parameters be monitoredcontinuously?

‐

In a prior simulator training, it wasconfirmed that one procedure isneeded.

* When taking into account the entry
the procedures‐ Once* As well as the operation steps until
just before F&B implementation‐ Continuous monitoring

15

Can the operators verify the parameters required for implementing theapplicable operations from the front of the control panel, and need notleave the area in front of the control panel?

‐

In a prior simulator training
exercise, it was confirmed that thenecessary parameters were verified
from the front panel‐

16(Question necessary if the response to any of the following questions is YES‐ work load is high or there is confusion when the cue is given out in No.13,
continuous monitoring is required in No.14, and the operator needs tomove away from the panel for verifying the parameters in No.15)
Is the cue necessary for implementing the applicable operation an alarm or
the monitoring of instruments?

‐‐・When taking into account theprocedures,
The cue is the alarm・Alarm sounds before the operation,
but it is not just before.

33

Tsunami HazardGas turbine electric
generator

Transformer

Mobileequipment

Watertight doors
Sea water pump
SouthSeawall

44

Tsunami ProjectNorth：Watertightdoors

Transformer：Penetrations：SCsSeawall

Frequency of watertightdoor inadvertently left open

Guide to fragility
evaluation objects

Reactor building (R/B)

South

Seawater pump

Turbine building (T/B)

Closed coverTo water discharge port

IntakePenetrations damage probability andinundation amount

Structural and functional damage tooutdoor tsunami protection structure

55

Picture of Portable Water Supply Equipment
Mobile water intake pump
Mobile waterinjection pumpR/B

Freshwater tank

MCR
Hose expansion
Auto fuelsupply system(injection)

Command, report,and communication
TSC

Auto fuelsupply system(intake)

Fuel supply(repeat operation

Field

Tank lorry

Tank lorry

Underground
fuel tank66

Door inadvertently left open
Possible HFE occurrence
Emergency power
available: Interlock
enabledNormal power only.
Requires manual lockT/B

To the hill
Airtight
door

Airtight
door

Westside

R/B

Eastside

Watertightdoor

Watertightdoor

People in R/B are
instructed to evacuatefrom R/B to a hill77

With thanks to•

Yukihiro Kirimoto, NRRC

88