Operated by Los Alamos National Security, LLC for the U.S. Department of Energy's NNSA

Seismically Actuated Shut off Devices

Michael W. Salmon10/19/2016

Lessons Learned

10/20/2016 | 1Los Alamos National Laboratory

Presentation

10/20/2016 | 2Los Alamos National Laboratory

• Background• Use of seismically actuated shut

off devices at nuclear facilities• Standards for qualification of

seismically actuated shut off devices

• Criteria needed for acceptance• Lessons Learned

Background

10/20/2016 | 3Los Alamos National Laboratory

• New facilities at LANL• Existing facilities at LANL• Accident sequences involving deflagration or fire can be mitigated by

cutting off power to either heat sources or by minimizing the potential for ignitions (fire following earthquake)

• Savings potential for design of structures or components to lower seismic design category (SDC 2)

• Requires switch to be designated as Safety Class (SDC 3) • Questions/issues

– NQA-1 compliant nuclear grade or seismically qualified devices– Commercial grade dedication and testing of non nuclear grade devices– What is the testing criteria to be used in seismic qualification?– What level of ground motion should be used to trigger a “shut down”

Use of seismically actuated shut off devices at nuclear facilities

10/20/2016 | 4Los Alamos National Laboratory

1. LANL –– Kinemetrics ETNA using 2/3 logic and

0.10g peak ground acceleration trip point

– Apollo 2100 Series seismic switch with trigger threshold 0.10g

2. Diablo Canyon Nuclear Power Plant (DCPP)

– Kinemetrics TS-33A triaxial trigger part of plant protection system

– Syscom Model MR2002 triaxialaccelerometer – cuts of power supply to fuel handling building crane

3. Honeywell Metropolis Works Fuel Processing Plant

– Syscom system

Standards

10/20/2016 | 5Los Alamos National Laboratory

• IEEE – 344 – Seismic Qualification of Equipment for Nuclear Power Generating Stations

• ASCE 25-97 – Earthquake-Actuated Gas Shutoff Devices– Provides qualification criteria based on

single axis sine tests– Actuation Requirements– Non-Actuation Requirements

• ASME A17.1 – Safety Code for Elevators and Escalators– Mandates shut down of elevators when

vertical PGA > 0.15g• CA Code 3137

Criteria

10/20/2016 | 6Los Alamos National Laboratory

• What level of ground motion should the device trigger at?

• EPRI recommended that two criteria be looked at to determine when damage may be expected (PSA> 0.20g, CAV>0.16 g-sec)– Further studies have shown that the CAV

threshold of 0.16g-sec is a factor of safety of 3 below (0.5 g-s) lower than the lowest value associated with documented damage to buildings of good design and construction.

– CAV is a good indicator of damage, but requires processing

• Most common to trigger on peak ground (instrumental) acceleration– Requires little processing– Available

Criteria

10/20/2016 | 7Los Alamos National Laboratory

• Design basis for Nuclear Facility design and evaluation are based on Uniform Hazard Response Spectra

• There is a less than a 1% probability of failure for ground motion at the DBE• Project against SDC Ground Motions

– Uniform Hazard Spectra are not earthquakes– There is no single SDC/PC “earthquake” or event

1st Lesson

10/20/2016 | 8Los Alamos National Laboratory

• Understand what your instrument is measuring

• Where is it mounted?• Initial setpoints for the

Apollo system were based on adapting an ASCE 25 filter and increasing a “safety margin” in spectral response levels

• The Apollo system is mounted at grade and will measure ground acceleration – not spectral acceleration.

2nd Lesson

10/20/2016 | 9Los Alamos National Laboratory

• Understand how the instrument is sampling the ground motion and what (if any) digital filters are applied.

• The Apollo system uses a pair of digital filters to process incoming acceleration data– A low pass anti-alias filter that

attenuates high frequency signals– A user selectable band pass filter

• Standard filter (1-15 Hz)• ASCE 25-97 filter (1-5Hz)

• For calibration the reference accelerometers and acquisition system should be processing the input data similarly for an apples to apples comparison

2nd Lesson (cont)

10/20/2016 | 10Los Alamos National Laboratory

• If calibration is being performed or estimation of uncertainties you better know if the reference accelerometers and acquisition system are sampling and processing table motion similar to the test specimen

• Data Processing for the Mitigator+– Sampling at 400 sps from the

MEMS sensor– Anti-alias filter– Decimate to 100 sps– Band pass filter– Trigger detection

Run 131.0 Hz

MitigatorSerial No. Axis

MitigatorAccelerometer

Test PlateAccelerometer

Table Accelerometer

nigbor estimate

2072x X Axis 0.0452072y Y Axis 0.0292072z Z Axis 0.201 0.18 0.19 0.1112072v Vsum 0.208

2074x X Axis 0.0392074y Y Axis 0.0322074z Z Axis 0.207 0.37 0.3 0.1212074v Vsum 0.213

2075x X Axis 0.0392075y Y Axis 0.0292075z Z Axis 0.201 0.18 0.15 0.1092075v Vsum 0.207

2076x X Axis 0.0412076y Y Axis 0.0342076z Z Axis 0.201 0.28 0.24 0.1212076v Vsum 0.208

2078x X Axis 0.0452078y Y Axis 0.032078z Z Axis 0.213 0.26 0.2 0.1112078v Vsum 0.220

2079x X Axis 0.042079y Y Axis 0.0272079z Z Axis 0.206 0.27 0.21 0.1112079v Vsum 0.212

2080x X Axis 0.0372080y Y Axis 0.0272080z Z Axis 0.204 0.26 0.2 0.1112080v Vsum 0.209

3rd Lesson

10/20/2016 | 11Los Alamos National Laboratory

• Its best to overestimate uncertainties associated with setpoints• Setpoint calculations performed per ISA-RP67.04.02-2000 address uncertainties

– Sensor Error– Drift– Calibration error– Many more

Margin must be sufficient to address uncertainties in setpoint

4th Lesson

10/20/2016 | 12Los Alamos National Laboratory

• Communicate early and often• Understand what the device is measuring and triggering against and the test

protocol being used.

5th Lesson

10/20/2016 | 13Los Alamos National Laboratory

• Is the ASCE 25 test protocol appropriate?– Single axis sinusoidal test at 4 or 5

distinct frequencies– Slowly (0.01g/second) increase

amplitude until device activates or must actuate level has been exceeded

• When would it be appropriate?• What would be better?

Recommendations

10/20/2016 | 14Los Alamos National Laboratory

• Can filtered ground motion (peak acceleration) be compared to the UHRS peak ground acceleration associated with design?

• There is a need for a national standard to address the seismic qualification of seismically actuated devices such as this - ASCE 25 may not be the proper venue.