Fukushima: Outside the Imagination and Lack of Preparation ... · Yokogawa Electric Corporation,...

1Yokogawa Electric Corporation, Japan + ChinaTadaaki Ando, Han Jie

Fukushima:

Outside the Imagination and Lack of Preparation

&

Benefit of PST (Partial Stroke Test)

International TÜV Rheinland Symposium in ChinaFunctional Safety in Industrial Applications18 – 19 October 2011, Shanghai - China


Part1: Fukushima - East coast Japan earthquake

� At 14:46 Japan time of March 11, 2011

� Offshore about 150 km from Sendai.

� Two earthquakes followed- 150 seconds- 100 km south gap.

� Source region - 100 km wide - 500 km length

� Tsunami to Over 500 km coast area


Part1: Fukushima - Historic scale disaster and victi ms

� １．１．１．１． M 9.5 : Chile (1960 05 22) � ２．２．２．２． M 9.2 : Prince William Sound, Alaska (1964 03 28)� ３．３．３．３． M 9.1 : Sumatra-Andaman Islands (2004 12 26)

� ４．４．４．４． M 9.0 : Near the East Coast of Honshu, Japan (2011 03 11)� ５．５．５．５． M 9.0 : Kamchatka (1952 11 04)� ６．６．６．６． M 9.0 : Arica, Peru (now Chile) (1868 08 13)� ７．７．７．７． M 9.0 : Cascadia Subduction Zone (1700 01 26)

� 15,750 people dead, 4059 is still missing, and inju red 5932. � 92.5 percent of the victims are by the Tsunami.

� Height of the Tsunami was mostly 5-15m.� Highest point was 38.9m!


� Japan's nuclear power plants are on the coast for c ooling. � Fukushima Dai-1 is BWR and Japan's oldest nuclear p ower plant

in 1971.

� All the nuclear power plants in the area successfully stopped after the earthquake.

� Only Fukushima Dai-1 (=No.1) had the accident.

� Facilities for external power supply, includes tran smission towers are broken by the earthquake. No way to receive ext ernal power.

Part1: Fukushima - Fukushima Dai1- nuclear power stat ion

Fukushima Dai-1 Nuclear Power Station (TEPCO)


Part1: Fukushima - Fukushima Dai-1 nuclear power sta tion

� 1 hour later, 14 to 15m height of Tsunami rushed to the station.-> Reactor/Turbine building are flooded.-> Emergency diesel power generators were submerged .-> Battery of ECSS (Emergency Core Cooling System) has gone after 8 hours.

� All cooling system were lost.

� Several hours later, 3 reactors had meltdown.

Tsunami hits to Dai-1 Nuclear Power Station (TEPCO)


Part1: Fukushima - Tsunami to Fukushima Dai-1

� M7 class earthquake is considered as a possible ri sk. � M8 or beyond has considered very remote, no chance. � Expected maximum height of Tsunami is 5.6m. � But M9 was happened and Tsunami was 15.6m.

(TEPCO))15.5m above sea level


Part1: Fukushima - Fukushima Dai-2

� Fukushima Dai-2 (No.2) Nuclear power station10km south of the Fukushima Dai-1

� It is Japan's second oldest nuclear power plant in 1982.� Both are BWR and basic design is same. � All facilities of both of Dai-1 & Dai-2 could stand against the

earthquake

� However, Fukushima Dai-2 safety stopped didn’t have any accident like Dai-1.

� What divided the big difference of consequences?

Fukushima Dai-2 Nuclear Power Station (TEPCO)


Part1: Fukushima - Lucky of Fukushima Dai-2

Dai-1 Dai-2 Site altitude from sea level 10m 12mBack-up diesel generator Turbine building Reactor bu ilding

(Ocean side) (Mountain side)

�Reactor building has better airtightness than turbin e building.�Dai-2 could kept its power for cooling and other fa cilities.

ReactorTurbine

sea level10m

ReactorTurbine

sea level12m

Fukushima Dai-1 Fukushima Dai-2


Part1: Fukushima - Dilemma

� Another geological survey, Fukushima area had M8 cl ass with 9m of Tsunami once per 1,000 years, from 3,000 years a go.

� How we could assume an interval of 15m height Tsuna mi? � How large earthquake (disaster) we should prepare?

� Installing facility on 30m above sea level is possi ble. However, it creates other risks, i.e. lost of functions of pump ing up the sea water for cooling.

� There is no easy answer for risk assessment. � Also Fukushima Dai-1 shows a difficulty of consider ing common

failure by disaster.


Part 2

Benefit of PST (partial stroke test)


HIS (DCS

Operator Interface)

Transmittersw/Diagnostics

ESD Valvesw/Diagnostics

(PRM)Plant Resource Management

ProcessController

Safety Controller

Transmittersw/Diagnostics

Control Valvesw/Diagnostics

Part2: Benefit of PST (partial stroke test) - Horizontal / Vertical integration

� “Horizontal” integration: Process and system informa tion (data, alarm & event) of both of DCS and SIS are integrate d in common operator HIS (Human-machine interface station).

� “Vertical” integration: Diagnosis information of int elligent field devices for both of DCS and SIS are integrated in t he common PRM (Plant resource management) window.


Part2: Benefit of PST (partial stroke test)- Proof test of ESD valve

� Proof test for ESD valves are most important part t o maintain the safety functions.

� FST (full stroke test) - Confirm the full closure of the valve. - 100% coverage- Need process interruption (stop), or bypass instal lation- Time consuming and costly.

� PST (Partial stroke test)- Confirm the partial (small) closure of the valve. - Diagnostic coverage is not 100%. No guarantee of f ull closure.- No need to stop the process


Part2: Benefit of PST (partial stroke test)- Legacy style FST/PST

� Old style FST without interrupting the process - Installation of bypass route and manual valve on i t.

� Old style PST without interrupting the process - introduce a valve with some measure for PFT.

� Both has - Many manual procedures includes manual recording- Coordination between field engineer and asset mana ger

� Inherently include a chance of the human errors.


Part2: Benefit of PST (partial stroke test)- Legacy style FST with bypass

� Bypass pipe and manual valve must be installed.� How to test:� 2 engineers (A & B) must be in the field. � “B” visits the rack room.� “A” visits the valve.� “A” opens the manual valve.� “B” shorts the terminal by a jumper.� “A” confirms the closure.� “B” removes the jumper.� “A” confirms the open.� “A” closes the manual valve.� “A” or “B” records the test.

SIS

“B”

“A”


Part2: Benefit of PST (partial stroke test)- Legacy style FST with bypass

� Many chances of human-error to cause a dangerous failure, or a false trip

� “A” opens the manual valve.

� “B” shorts the terminal by a jumper.

� “B” removes the jumper.

� “A” closes the manual valve.

� “A” or “B” records the test.

SIS

“B”If “A” opens the wrong manual valve.

If “B” shorts wrong terminal by a jumper.

If “B” forgets to remove the jumper.

If “A” or “B” forgets to record the test.

If “A” forgets to close the valve.“A”


Part2: Benefit of PST (partial stroke test)- Legacy style PST with block pin

� Use a pin to block the movement of stem.� How to test: � 2 engineers (A & B) must be in the field. � “B” visits the rack room.� “A” visits the valve.� “A” inserts the pin to the valve.� “B” shorts the terminal by a jumper.� “A” confirms some closure.� “B” removes the jumper.� “A” confirms full open.� “A” removes the pin.� “A” or “B” records the test.

SIS

“B”

“A”


Part2: Benefit of PST (partial stroke test)- Legacy style PST with block pin

� Many chances of human-error to cause a dangerous failure, or a false trip

� “A” inserts the pin to the valve.

� “B” shorts the terminal by a jumper.

� “B” removes the jumper.

� “A” removes the pin.

� “A” or “B” records the test.

SIS

“B”

“A”

If “A” inserts the pin to the wrong valve.

If “B” shorts wrong terminal by a jumper.

If “B” forgets to remove the jumper.

If “A” or “B” forgets to record the test.

If “A” forgets to remove the pin.


Part2: Benefit of PST (partial stroke test)- New technologies

� Remote PST box- Small box next to the valve, push button to execut e PST , and indicator to confirm the result. - Still requires “someone needs to visit the valve”, weakest point. - Visiting valves is costly and troublesome work.

especially in the remote and distributed site. - No integration to the PRM (Plant Resource Manager) ,

the asset management software.

� PST from PC- Software commanding from PC- Based on the field digital technology. - No need to visit valve.- Not common among the vendors.- No integration to the PRM (Plant Resource Manager) software.


Part2: Benefit of PST (partial stroke test)- PST Scheduler, the latest and common solution

� PST Scheduler

� Common interface for different valve venders.

- Easy interface for scheduling of PST and monitorin g the results.

- Common workplace of PST for multiple venders.

- Based on the common technology platform (HART, FDT /DTM)

- Integration to PRM. The result of the test is inte grated to PRM.

- PST Scheduler client is available on the operator station, not only

the safety engineering station. Operator can initia te cancel, and

confirm PST.


Part2: Benefit of PST (partial stroke test)- “PST Scheduler”



� Easy calendar based scheduling� Results and coming test are on one window


� Common interface for different valve venders.� Integrated to the PRM software. � Client can be on HIS (Operator station)

for closer relationship between operation and maint enance.� Based on FDT/DTM technology� Detail is available to upload



Fukushima: Outside the imagination, & Benefit of PST (partial stroke test)

Conclusion� The disaster of Fukushima Nuclear Power station has been

caused very far rare large earthquake and Tsunami. However, a major disaster was not only the reason of the conse quences. Difficulty of risk assessment is a limitation of hu man imagination.

� The implication of the PST makes available not only reducing thecost and complexity for proof testing of the valve, but also reducing the likelihood of human error. The unified PST scheduler among multiple venders is confirmed that there are many conveniences to users.

Fukushima: Outside the Imagination and Lack of Preparation ... · Yokogawa Electric Corporation,...

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