© 2015 Electric Power Research Institute, Inc. All rights reserved.

John Richards

Principal Technical Leader

Pacific Rim Forum

University of California at Berkeley

June 9, 2015

EPRI Program on High

Frequency Testing

2© 2015 Electric Power Research Institute, Inc. All rights reserved.

EPRI High Frequency Program

1. Background on High Frequency Issues

2. EPRI High Frequency Program Purpose

and Scope

3. Component Test Program

4. High Frequency Component Evaluation

Criteria

3© 2015 Electric Power Research Institute, Inc. All rights reserved.

Ground motion estimates for some nuclear plant sites are

showing significant high frequency energy content

High Frequency Program – Background

4© 2015 Electric Power Research Institute, Inc. All rights reserved.

Seismic High Frequency – Background

In the late 1980s

EPRI and LLNL Hazard Studies suggested ground motions

could have significant amounts of high-frequency content

– Evaluation guidance was developed focusing on limited

displacements in high frequency motions

In the 2000s

Improved seismic hazard models included increased high-

frequency motions, especially for hard rock sites

New plant licensing criteria in the U.S. used the seismic

hazard to determine the site-specific seismic demand, which

brought the high-frequency issue to the forefront

– Additional guidance was developed with recommendations for

evaluating high frequency motions within the design process

5© 2015 Electric Power Research Institute, Inc. All rights reserved.

Seismic High Frequency – Background

Plotted as spectral accelerations,

the high frequency motions are

significant.

Plotted as spectral displacements,

the high frequency motions are

not significant.

𝑆𝑑 = 𝑆𝑎

2𝜋𝑓 2

6© 2015 Electric Power Research Institute, Inc. All rights reserved.

Seismic High Frequency – Background

NRC issued GI-199 to examine the issue of increased

seismic hazards on operating plants

NRC Near Term Task Force recommendations for seismic

evaluations asked licensees to estimate their seismic

hazards and GMRS using current criteria for new

plants

– EPRI report 1025287 (the SPID),

provided screening and evaluation

guidance for responding to the NRC

request for information, including

guidance for the treatment of high

frequency exceedances

7© 2015 Electric Power Research Institute, Inc. All rights reserved.

Identify components potentially vulnerable to loss of function

due to high-frequency vibratory motion

– Develop capacity data using shake table tests for potentially high-

frequency sensitive components

– Use accelerations that are high enough to address anticipated high-

frequency in-structure and in-cabinet responses of various plants

Identify resolution strategies

for components that prove

to be sensitive to high-

frequency motions

High Frequency Program – Purpose

8© 2015 Electric Power Research Institute, Inc. All rights reserved.

High Frequency Program – Phase 1

Random Multi-

frequency

0

1

2

3

4

5

6

10 100

Spec

tral

Acc

eler

atio

n (

No

rmal

ized

)

Frequency, Hz

HF SB1

HF SB2

HF SB3

HF SB4

HF SB5

HF SB6

HF SAwb

1 2 3 4 5 6

RMF + sine

beats

Test a limited number of components using a variety of

test methods to determine the optimal test protocol

Sine sweeps

(16 Hz to 64

Hz)

9© 2015 Electric Power Research Institute, Inc. All rights reserved.

Sine Sweep – 7.5g Front/Back, ~18 Hz

10© 2015 Electric Power Research Institute, Inc. All rights reserved.

Sine Sweep – 7.5g Front/Back, ~30 Hz

11© 2015 Electric Power Research Institute, Inc. All rights reserved.

Phase 1 Conclusions and Insights (EPRI 3002000706)

The multi-frequency input motion was the best input motion for determining high-frequency sensitivity. The 20 to 40 Hz frequency range was the best range for determining high-frequency sensitivity.

– The 16 to 32 Hz range overlapped more than necessary with standard testing

– The 24 to 48 Hz range did not provide significantly different results but could leave a gap between standard testing and the high-frequency testing

High-frequency sensitivity of contact devices is model specific; therefore, specific component testing was required

12© 2015 Electric Power Research Institute, Inc. All rights reserved.

High Frequency Program – Phase 2

Test a broad range of components with a diverse set of

manufactures and model numbers representative of

components installed in plants

Test using increasing acceleration levels until the

component fails the test or shake table limits are reached

13© 2015 Electric Power Research Institute, Inc. All rights reserved.

Test Sample Distribution

Testing performed on 153 items

Results are documented in

EPRI Report 3002002997

14© 2015 Electric Power Research Institute, Inc. All rights reserved.

Sample Results – Contactors & Motor Starters

15© 2015 Electric Power Research Institute, Inc. All rights reserved.

Key Test Program Conclusions (EPRI 3002002997)

Most components are very rugged

in the high-frequency range,

passing the tests without contact

chatter or malfunction at shake

table limits

Components that showed contact

chatter at high-frequency

accelerations less than 10g were compared with

previous results from 4.5 Hz to 16 Hz frequency range

In all cases, the high-frequency capacity was equal to or

great than the low-frequency capacity

No unique high-frequency sensitivities were identified

16© 2015 Electric Power Research Institute, Inc. All rights reserved.

Test results suggest components do not have unique high

frequency vulnerabilities

Amplification of high frequency ground motions in

structures and in electrical cabinets is not well known

What options are there for improving the in-structure and

in-cabinet response spectra estimates?

High Frequency Evaluation Criteria

17© 2015 Electric Power Research Institute, Inc. All rights reserved.

Together…Shaping the Future of Electricity

18© 2015 Electric Power Research Institute, Inc. All rights reserved.

Backup Slides

19© 2015 Electric Power Research Institute, Inc. All rights reserved.

• Electro-mechanical relays

(e.g., control relays, time delay

relays, protective relays)

• Circuit breakers

(e.g., molded case and power

breakers – low and medium

voltage)

• Control switches

(e.g., benchboard, panel,

operator switches)

• Electro-mechanical contactors

(e.g., MCC starters)

• Process switches and switches

(e.g., pressure, temperature, flow,

limit/position)

• Auxiliary contacts

(e.g., subcomponents

of MCCBs, contactors / starters)

• Transfer switches

(e.g., low and medium voltage

switches with instrumentation)

• Potentiometers (without locking

devices, and subcomponents

of relays)

High Frequency Program – Scope

Component type list from SPID Table 3-3 (EPRI 1025287)

20© 2015 Electric Power Research Institute, Inc. All rights reserved.

Applicable EPRI Reports

NP-7498, Industry Approach to Severe Accident Policy Implementation, November 1991

EPRI 1015108, Program on Technology Innovation: The Effects of High-Frequency Ground Motion on Structures, Components, and Equipment in Nuclear Power Plants, June 2007

EPRI 1015109, Program on Technology Innovation: Seismic Screening of Components Sensitive to High-Frequency Vibratory Motions, October 2007

EPRI 1025287, Seismic Evaluation Guidance: Screening, Prioritization and Implementation Details (SPID) for the Resolution of Fukushima Near-Term Task Force Recommendation 2.1: Seismic, February 2013

EPRI 3002000706, High Frequency Program, Phase 1 Seismic Test Summary, September 2013

EPRI 3002002997, High Frequency Program, High Frequency Testing Summary, September 2014