Ministry of Economy, Trade and Industry, Government of Japan

On the Upgrading of JapaneseExamination Guide for Aseismic Design of

Nuclear Power Reactor Facilities

Shuji Kawahara and Kenji Takashima

Ministry of Economy, Trade and Industry, Government of Japan

Contents of the Presentation1. Upgrading of Japanese Examination Guide for

Aseismic Design of Nuclear Power Reactor Facilities

2. A Methodology to Determine Design EarthquakeGround Motion Which Might Occur in the Hidden Seismic Source

3. Short Report of EQ. Observation at Reactor Bldg.s in Kashiwazaki-Kariwa Nuclear Power Station

Ministry of Economy, Trade and Industry, Government of Japan

Upgrading of the Aseismic Design Examination Guide

- Japanese “Examination Guide for Aseismic Design of Nuclear Power Reactor Facilities” had established over 20 years ago

- The Examination Guide is now under the process of upgrading by the Nuclear Safety Commission of Japan.

- The major points of the discussion on upgrading are:1) The fundamental way of thinking about the safety

evaluation of the seismic design.2) Classification of seismic safety importance.3) Earthquake ground motion for seismic design.4) Evaluation of the seismic safety of the facilities.

- The works and discussions are currently still on going.

Ministry of Economy, Trade and Industry, Government of Japan

Classification of Seismic Safety Importance

Class Structure System and Component (SSC) Design Load

I

SSCs having radioactive materials inside SSCs directly related to other SSCs of aboveSSCs needed to avoid radioactive material release SSCs needed to shutdown the reactorSSC needed to reduce an influence by theradioactive material release in the atmosphere

Design Earthquake of Ss(Static seismic load of 3.0CI ?)

II SSCs whose influence and effect is small as compare to the the seismic class I.

Static seismic load of 1.5CI

III SSCs other than the seismic classes of I and IIStatic seismic load of 1.0CI

For upgrading, the classes A and As are proposed to be integrated

Ministry of Economy, Trade and Industry, Government of Japan

The earthquake ground motion Ss is proposed1) Take into account the past earthquake ground motion and

ground motion caused by active faults. “Seismo-techtonic” knowledge is also considered for reference.

2) Consider the earthquake ground motion presumed without specifying the seismic sources based on a probabilistic study and/or past earthquake records obtained in the neighborhood of epicenters without seismic fault in the inland cluster earthquakes.

3) Check the probability of the ground motion level of Ss afterdesign.

4) Earthquake ground motion in the vertical direction at free field be also determined.

The Ss design earthquake is based on the concept of S2

Ministry of Economy, Trade and Industry, Government of Japan

Earthquake Ground Motion for Seismic Design- Consideration of the EQ Ground Motion due to Hidden Fault -

Period (sec)Period (sec)

EQ Ground MotionShould be Considered at LeastTypical EQs Due to

Hidden Fault Worldwide

Ground Motion Records of 6 EQs

Period (sec)

Seismic Bedrock

Hor. Motion

Period (sec)

Seismic Bedrock

Hor. Motion

Period (sec)

Seismic Bedrock

Hor. Motion

Period (sec)

Seismic Bedrock

Hor. Motion

Period (sec)Period (sec)

Seismic Hazard SpectraAnnual Exceedance Prov.

10-310-4

10-5

Period (sec)Period (sec)Period (sec)Period (sec)

Seismic Hazard SpectraAnnual Exceedance Prob.

10-310-4

10-5

Probabilistic EQ HazardAnalysis with Fault

Model for NFE(Mj=6, 6.6, 6.8, 7.3)

The Spectrum is Corresponding toAnnual Exceedance Prob. of 10-4

Ministry of Economy, Trade and Industry, Government of Japan

List of Earthquakes Whose Seismic Sources are not Found Clearly

The 1991 Sierra Madre Earthquake, Mw:5.6The 1978 Santa Barbara Earthquake, Mw:5.8The 1979 Coyote Lake Earthquake, Mw:5.8The 1987 Whittier Narrow Earthquake, Mw:6.0The 1984 Nagano-ken Seibu Earthquake, Mw:6.1The 1984 Morgan Hill Earthquake, Mw:6.2

Ministry of Economy, Trade and Industry, Government of Japan

Current Status of Upgrading of the Examination Guide

Preparation Works are in the Final Stage,However, Discussions are Still on-going

In Particular in Handling of the Methodology for Evaluating Seismic Safety of the Facilities.

Ministry of Economy, Trade and Industry, Government of Japan

EQ Observation at Reactor Bldg.s in an NPS during 2004 Niigata-ken Chuetsu EQ on an NPS

Kashiwazaki-Kariwa Nuclear Power Station (7 Units)

Ministry of Economy, Trade and Industry, Government of Japan

Relationship b/w Observed EQ Ground Motion & Design EQ., S1

Veloc

ity (c

m/sec

)

Design EQ GM of S1

Niigata EQ, Mj6.8, 22km

Period (sec)Six Units Had been Kept Operating w/o Any Problem, One Unit was Under Periodical Inspection

Mw:6.6

Ministry of Economy, Trade and Industry, Government of Japan

Observed Acceleration at Unit 5 Reactor Building

26.7Gal., 58.5Gal., 55.9Gal.

42.8Gal.,79.9Gal., 57.9Gal.

52.8Gal., 95.2Gal., 58.1Gal.

75.2Gal., 267.4Gal., 221.5Gal.

83m

75m

Ministry of Economy, Trade and Industry, Government of Japan

Observed Acceleration at Unit 6 Reactor Building

33.9Gal., 58.5Gal., 67.8Gal.

42.6Gal.,63.4Gal., No Obs.

73.7Gal., 83.9Gal., 80.0Gal.

139.6Gal., 118.4Gal., 110.7Gal.

At Free Field

(-2.7m)

78.8Gal.131.8Gal.59.7Gal.

Ministry of Economy, Trade and Industry, Government of Japan

Incidental Event (Nov. 4, 2004)The Unit 7 Had Tripped by the After Shock (Mj: 5.2, Depth: 18km) in the Morning of Nov. 4, 2004 due to the Signal of Turbine Axis Displ. in the Thrust Bearing Exceeding the Trip Level.After the Trip the Plant was Inspected and Found No Damage.

Then the Plant HadBeen Restarted 7days after the Trip.

Thrust Bearing Coupling

Hi-pressure Turbine Rotor Low-pressure Turbine Rotor

3 Gap Sensors

Ministry of Economy, Trade and Industry, Government of Japan

The End

Thank You