Information Notice 1994-32, Revised Seismic Estimates

Revised Seismic Estimates

ML031210542
Person / Time
Site:	Beaver Valley, Millstone, Hatch, Monticello, Calvert Cliffs, Dresden, Davis Besse, Peach Bottom, Browns Ferry, Salem, Oconee, Mcguire, Nine Mile Point, Palisades, Palo Verde, Perry, Indian Point, Fermi, Kewaunee, Catawba, Harris, Wolf Creek, Saint Lucie, Point Beach, Oyster Creek, Watts Bar, Hope Creek, Grand Gulf, Cooper, Sequoyah, Byron, Pilgrim, Arkansas Nuclear, Braidwood, Susquehanna, Summer, Prairie Island, Columbia, Seabrook, Brunswick, Surry, Limerick, North Anna, Turkey Point, River Bend, Vermont Yankee, Crystal River, Haddam Neck, Ginna, Diablo Canyon, Callaway, Vogtle, Waterford, Duane Arnold, Farley, Robinson, Clinton, South Texas, San Onofre, Cook, Comanche Peak, Yankee Rowe, Maine Yankee, Quad Cities, Humboldt Bay, La Crosse, Big Rock Point, Rancho Seco, Zion, Midland, Bellefonte, Fort Calhoun, FitzPatrick, McGuire, LaSalle, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant, Crane
Issue date:	04/29/1994
From:	Grimes B Office of Nuclear Reactor Regulation
To:
References
-nr, NUREG-1488 IN-94-032, NUDOCS 9404250004
Download: ML031210542 (6)

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C.

20555

April 29, 1994

NRC INFORMATION NOTICE 94-32: REVISED SEISMIC HAZARD ESTIMATES

Addressees

All holders of operating licenses or construction permits for nuclear power

reactors.

Purpose

The U.S. Nuclear Regulatory Commission (NRC) is issuing this information

notice to alert addressees to NUREG-1488, "Revised Livermore Seismic Hazard

Estimates for 69 Sites East of the Rocky Mountains," published in April 1994.

It is expected that recipients will review the information for applicability

to their facilities, specifically with regard to the Individual Plant

Examination of External Events (IPEEE) process.

However, suggestions

contained in this information notice are not NRC requirements; therefore, no

specific action or written response is required.

Description of Circumstances

During the 1980s, two probabilistic seismic hazard studies were undertaken, one by the Lawrence Livermore National Laboratory (LLNL), as documented in

NUREG/CR-5250, "Seismic Hazard Characterization of 69 Nuclear Plant Sites East

of the Rocky Mountains," dated January 1989, and another by the Seismicity

Owners Group/Electric Power Research Institute (SOG/EPRI), as documented in

EPRI NP-4726, 'Seismic Hazard Methodology for the Central and Eastern United

States," dated July 1986. These studies were performed in an effort to

improve the estimation of the seismic hazard that can be expected anywhere in

the United States east of the Rocky Mountains.

The results of these studies

produced significantly different seismic hazard predictions in terms of the

absolute values of the probability of exceeding specific levels of earthquake

induced ground motion.

However, the results of both studies were consistent

in terms of the relative seismic hazard from site to site.

The consensus of

the NRC staff and its consultants was that the differences in the results were

not driven by the difference in methodologies, but rather were a result of the

difference in the way in which the uncertainties in seismicity models and

ground motions models were propagated through the computational processes of

the two methodologies. In 1992, LLNL conducted another study under the

sponsorship of the NRC using a revised method for elicitation of seismicity

parameters, ground motion estimates, and the uncertainties associated with

those parameters and estimates.

The results of the new study were published

for comment in draft NUREG-1488 in October 1993.

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IN 94-32 April 29, 1994 The seismic hazard estimates calculated in the original LLNL study and in the

EPRI NP-4726 study were considered in the preparation of NUREG-1407,

"Procedural and Submittal Guidance for the Individual Plant Examination of

External Events (IPEEE) for Severe Accident Vulnerabilities," published in

June 1991.

The results of the new LLNL study are substantially different from

those of the previous LLNL study. Also, the EPRI study has not been revised

since its publication in 1986.

Therefore, the staff considers the results of

the new LLNL study to represent the best available information on seismic

hazard estimates.

Discussion

The consensus among experts associated with the probabilistic seismic hazard

analyses (PSHA) was that the large differences between the median hazard

estimates and the mean hazard estimates in the LLNL PSHA results were

primarily caused by the large uncertainty factors that accompanied the seismic

recurrence and ground motion models. In 1992, LLNL contacted the seismicity

and ground motion experts from the original study as well as several others to

elicit the required information using techniques that allowed the experts to

be more precise about their estimates.

Using a slightly modified version of

the original LLNL Probabilistic Seismic Hazard Methodology, LLNL recalculated

the seismic hazard estimates for all the nuclear power plant sites east of the

Rocky Mountains. The results exhibited significant reductions in the observed

spread between the median and the mean estimates of the hazard data.

Subsequently, NRC published the revised seismic hazard estimates for all

operating nuclear power plant sites east of the Rocky Mountains as draft

NUREG-1488 for comment.

The NRC received comments from two nuclear industry

companies.

These comments neither contested nor suggested amendments to the

technical data conveyed by draft NUREG-1488.

Instead, these comments

suggested changes in the IPEEE program scope.

Therefore, NUREG-1488 has been

published with no technical changes.

The NRC staff is reviewing the new information described above to see if it is

appropriate to revise the IPEEE seismic scope.

NRC review of the scope of the

current seismic IPEEE process may identify plants whose scope of investigation

can be reduced based on the new hazard information.

Any modifications of the IPEEE process by the NRC will neither necessitate a

revision to, nor have any impact on, efforts by licensees who have completed

their seismic IPEEE or are near completion, or plan to proceed with the

current guidance of Generic Letter 88-20, Supplement 4 and NUREG-1407.

Licensees who have not completed the seismic portion of the IPEEE may continue

with their programs and submit their completed IPEEEs for staff review based

on the previous studies or submit a request to adjust their IPEEE schedule to

take the new information into account.

'-'/

IN 94-32 April 29, 1994 This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact

one of the technical contacts listed below or the appropriate Office of

Nuclear Reactor Regulation (NRR) project manager.

Rev

'Fiian K. Grimes, Director

Division of Operating Reactor Support

Office of Nuclear Reactor Regulation

Technical contacts:

Gus Giese-Koch, NRR

(301) 504-2736

Ron Hernan, NRR

(301) 504-2010

Attachment:

List of Recently Issued NRC Information Notices

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IN 94-32

April 29, 1994 LIST OF RECENTLY ISSUED

NRC INFORMATION NOTICES

Information

Date of

Notice No.

Subject

Issuance

Issued to

94-31

90-68, Supp. 1

94-30

94-29

92-51, Supp. 1

94-28

94-27

Potential Failure of

Wilco, Lexan-Type HN-4-L

Fire Hose Nozzles

Stress Corrosion Cracking

of Reactor Coolant Pump

Bolts

Leaking Shutdown Cooling

Isolation Valves at

Cooper Nuclear Station

Charging Pump Trip during

a Loss-of-Coolant Event

Caused by Low Suction

Pressure

Misapplication and

Inadequate Testing of

Molded-Case Circuit

Breakers

Potential Problems with

Fire-Barrier Penetration

Seals

Facility Operating

Concerns Resulting from

Local Area Flooding

Personnel Hazards and

Other Problems from

Smoldering Fire-Retard- ant Material in the

Drywell of a Boiling-

Water Reactor

Safety Systems Response

to Loss of Coolant and

Loss of Offsite Power

04/14/94

04/14/94

04/12/94

04/11/94

04/12/94

04/05/94

03/31/94

03/28/94

03/25/94

All holders of OLs or CPs

for nuclear power reactors.

All holders of 01 or CPs

for pressurized water

reactors.

All holders of OLs or CPs

for nuclear power reactors.

All holders of OLs or CPs

for pressurized water

reactors.

All holders of OLs or CPs

for nuclear power reactors.

All holders of OLs or CPs

for nuclear power reactors.

All holders of OLs or CPs

for nuclear power reactors.

All holders of OLs or CPs

for nuclear power reactors.

All holders of OLs or CPs

for nuclear power.

93-17, Rev. 1 OL = Operating License

CP - Construction Permit

IN 94-32 April 29, 1994 This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact

one of the technical contacts listed below or the appropriate Office of

Nuclear Reactor Regulation (NRR) project manager.

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Brian K. Grimes, Director

Division of Operating Reactor Support

Office of Nuclear Reactor Regulation

Technical contacts:

Gus Giese-Koch, NRR

(301) 504-2736

Ron Hernan, NRR

(301) 504-2010

Attachment:

List of Recently Issued NRC Information Notices

• SeP

nrpvious concurrence

OFFICE

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IN 94-XX

April XX, 1994 This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact

the appropriate Office of Nuclear Reactor Regulation (NRR) project manager.

Brian K. Grimes, Director

Division of Operating Reactor Support

Office of Nuclear Reactor Regulation

Technical contacts:

Gus Giese-Koch, NRR

(301) 504-2736

Ron Hernan, NRR

(301) 504-2010

Attachment:

List of Recently Issued NRC Information Notices

• See Drevious concurrence

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