ML020840181

Ltr to L. Womack, Diablo Canyon Power Plant, Acceptance Review for the Diablo Canyon Independent Spent Fuel Storage Installation Application

ML020840181
Person / Time
Site:	Diablo Canyon
Issue date:	03/25/2002
From:	Steven Baggett NRC/NMSS/SFPO
To:	Womack L Pacific Gas & Electric Co
References
+sispmjr200505, -nr, -RFPFR, TAC L23399
Download: ML020840181 (6)

Text

March 25, 2002 Mr. Lawrence F. Womack Vice President, Nuclear Services Diablo Canyon Power Plant P.O. Box 56 Avila Beach, CA 93424

SUBJECT:

ACCEPTANCE REVIEW FOR THE DIABLO CANYON INDEPENDENT SPENT FUEL STORAGE INSTALLATION APPLICATION

Dear Mr. Womack:

This responds to Pacific Gas and Electrics (PGE) December 21, 2001, application for a 10 CFR Part 72 license to build and operate an independent spent fuel storage installation (ISFSI) at the Diablo Canyon Power Plant. The purpose of this letter is to inform you that the U.S. Nuclear Regulatory Commission (NRC) has completed its initial acceptance review of the application. The staff found that the application contains sufficient information for the staff to initiate its technical review. Please note that this acceptance review only determined that the information was submitted in accordance with the guidelines established in NUREG-1567, Standard Review Plan for Spent Fuel Dry Storage Facilities. The acceptance review was not intended to determine the technical adequacy of the application.

In the course of the acceptance review, the staff identified several technical areas for which they will require clarification (see Enclosure). The staff proposes that these areas be discussed on April 11, 2002, during a meeting in San Francisco, CA, that will be open for public observation, regarding geotechnical evaluations performed to support your license application.

In addition, during the NRC site tour of Diablo Canyon on April 9, 2002, please be prepared to discuss which operations in the fuel handling building will be performed under your 10 CFR Part 50 license and which operations will be performed under a 10 CFR Part 72 license. The tour should include references to all potential accident conditions, such as accidents involving the transporter, transport station, and storage casks. These issues may later be the subject of a request for additional information by the staff.

This letter was also intended to notify you of the NRCs schedule to perform the technical review of the application. However, on March 18, 2002, your staff requested the NRC to postpone issuing the final review schedule until after the March 28, 2002, management meeting between NRC and PG&E. Therefore, the technical review schedule will not be issued until the first week in April 2002.

L. Womack Please reference Docket No. 72-26 and TAC No. L23399 in future correspondence related to this licensing action. If you have any questions, please contact me at (301) 415-8584.

Sincerely,

/RA/

Steven Baggett, Senior Project Manager Licensing Section Spent Fuel Project Office Office of Nuclear Material Safety and Safeguards Docket No. 72-26 (50-275, -323)

TAC No. L23399

Enclosure:

Technical Areas Which Require Clarification cc: Mailing List

L. Womack Please reference Docket No. 72-26 and TAC No. L23399 in future correspondence related to this licensing action. If you have any questions, please contact me at (301) 415-8584.

Sincerely,

/RA/

Steven Baggett, Senior Project Manager Licensing Section Spent Fuel Project Office Office of Nuclear Material Safety and Safeguards Docket No. 72-26 (50-275, -323)

TAC No. L23399

Enclosure:

Technical Areas Which Require Clarification cc: Mailing List Distribution:

NRC File Center PUBLIC NMSS r/f SFPO r/f WHodges CMiller EWBrach EEaston JGuttmann HLee GShukla, NRR EKeegan CBrown JSolis CBajwa CWithee MDelligatti File Name/Location)C:\Program Files\Adobe\Acrobat 4.0\PDF Output\Acceptance Review Letter.wpd *see previous concurrence OFC: SFPO C SFPO SFPO SFPO SFPO NAME: Kobetz for EZiegler* JMonninger* CMiller WHodges SBaggett*

DATE: 3/21/02 3/21/02 3/22/02 3/25/02 3/22/02 OFFICIAL RECORD COPY

Technical Areas Which Require Clarification The following areas should be discussed at the April 11, 2002, meeting between the U. S.

Nuclear Regulatory Commission and Pacific Gas and Electric. The meeting will be held in San Francisco, California.

Stability of Subsurface Materials or Stability of Slopes Discuss the safety of the proposed facility considering the stability of natural and proposed cut slopes and the movement of dislodged debris and rock materials that may arise from potential seismically induced slope instability. The assessment currently provided in the safety analysis report (SAR) Section 2.6.5 does not appear to appropriately represent the strength of the clay-bed soil, nor provide technical basis for the value of rock-mass strength, nor provide adequate representation of the design-basis ground motion in slope-safety analysis. These discussions should include the following:

Undrained Shear Strength of Clay Beds.

Discuss the saturated undrained shear strength of the clay-bed soil.

The undrained shear strength of the clay beds is given in SAR Section 2.6.4.3.2, Slopes, in terms of a cohesion c and friction angle . These parameters model the undrained shear strength of the clay beds using a straight-line relationship with normal stress. The undrained shear strength of an unsaturated soil, however, has an upper-bound value equal to the saturated undrained shear strength, cu (e.g., Reference 1, Figure 9.38). The undrained shear strength of an unsaturated soil may be represented using a straight-line relationship with normal stress as proposed in SAR Section 2.6.4.3.2, provided that the value of undrained shear strength obtained from the relationship is not permitted to exceed cu. The use of a straight-line relationship without an upper limit may cause the strength of the soil to be overestimated, resulting in an incorrect assessment of the stability of subsurface materials or slope stability.

The omission of the upper limit from the undrained-strength specification, therefore, has a potential effect on the assessment of the stability of subsurface materials (SAR Section 2.6.4) and slope stability (SAR Section 2.6.5) and on the staff review of the assessments to determine compliance with 10 CFR 72.122(b).

Rock-Mass Strength.

Discuss the technical basis (data and analysis) to justify the rock-mass friction angle of 50E used to characterize the rock-mass strength of dolomite (unit Tofb-1) and sandstone (Tofb-2).

Information provided in the SAR (e.g., Sections 2.6.4.3.1, 2.6.4.3.2, 2.6.5.1.2.3) indicates that this strength parameter was determined using the Hoek-Brown procedure (e.g., Reference 2 and Reference 3). The Hoek-Brown procedure would, however, result in values of friction angle significantly smaller than 50E for the rock-mass, considering the values of rock-mass quality index (GSI) and intact-rock parameter (mi) given in the data reports. A rock-mass friction angle of 50E would require a GSI>80 and mi>30 (e.g., Reference 2 and Reference 3), both of which exceed the values given for the dolomite (GSI.56 and mi.15) and sandstone (GSI.65 and mi.18) rock masses. The technical basis for the rock-mass friction angle should be presented since it has a potential effect on the assessment of the stability of subsurface materials (SAR Section 2.6.4) and slope stability (SAR Section 2.6.5) and on the staff review of the

2 assessments to determined compliance with 10 CFR 72.122(b).

Representation of Design Basis Earthquake in Slope Safety Analysis.

Discuss the evaluation of potential coupling of the effects of the three ground-motion components on slope safety. Information provided in SAR Section 2.6.5.1.3.4 suggests that the vertical component of the ground motion representing the design-basis earthquake (DBE) was not included in the analyses of slope stability.

The vertical ground-motion component would affect the slope stability indirectly through its effect on the shear resistance of the potential failure surface, and directly through its effect on the slope-parallel motion component. Therefore, excluding the vertical component from the analysis may lead to an incorrect assessment of slope stability. For this reason, the slope safety evaluation presented in the SAR, which was developed using the horizontal ground-motion components without the vertical component, should be clarified for the staff to determine compliance with 10 CFR 72.122(b).

References

1. Fredlund D.G. and H. Rahardjo. Soil Mechanics for Unsaturated Soils. New York, NY:

John Wiley & Sons, Inc. 1993.

2. Hoek E. and E.T. Brown. Practical estimates of rock mass strength. International Journal of Rock Mechanics and Mining Sciences and Geomechanics Abstracts, 34(8):

1165-1186. 1997.

3. Hoek E. Practical Rock Engineering: Chapter 11, Rock Mass Properties. Rocscience, Inc. http://www.rocscience.com/roc/Hoek/Hoeknotes2000.htm. 2000.

3 Diablo Canyon Power Plant, Units 1 and 2 cc:

NRC Resident Inspector Diablo Canyon Nuclear Power Plant Christopher J. Warner, Esq.

c/o U.S. Nuclear Regulatory Commission Pacific Gas & Electric Company P.O. Box 369 Post Office Box 7442 Avila Beach, CA 93424 San Francisco, CA 94120 Dr. Richard Ferguson, Energy Chair Mr. David H. Oatley, Vice President Sierra Club California Diablo Canyon Operations and 1100 11th Street, Suite 311 Plant Manager Sacramento, CA 95814 Diablo Canyon Nuclear Power Plant P.O. Box 3 Rochelle Becker Avila Beach, CA 93424 San Luis Obispo Mothers for Peace Telegram-Tribune 1037 Ritchie Rd. ATTN: Managing Editor Grover Beach, CA 93433 1321 Johnson Avenue P.O. Box 112 Chairman San Luis Obispo, CA 93406 San Luis Obispo County Board of Supervisors Mr. Ed Bailey, Radiation Program Director Room 370 Radiologic Health Branch County Government Center State Department of Health Services San Luis Obispo, CA 93408 P.O. Box 942732 (MS 178)

Sacramento, CA 94327-7320 Mr. Truman Burns Mr. Robert Kinosian Mr. Robert A. Laurie, Commissioner California Public Utilities Commission California Energy Commission 505 Van Ness, Room 4102 1516 Ninth Street (MS 31)

San Francisco, CA 94102 Sacramento, CA 95814 Mr. Steve Hsu Ms. Charlotte Alexander Radiologic Health Branch Vice President, Special Projects State Department of Health Services Green Car Group P.O. Box 942732 1241 Johnson Avenue #356 Sacramento, CA 94327-7320 San Luis Obispo, CA 93401 Diablo Canyon Independent Safety Ellen Carroll Committee Environmental Coordinator ATTN: Robert R. Wellington, Esq. Department of Planning and Building Legal Counsel County of San Luis Obispo 857 Cass Street, Suite D County Government Center, Room 310 Monterey, CA 93940 San Luis Obispo, CA 93408 Regional Administrator, Region IV The Honorable Lois Capps U.S. Nuclear Regulatory Commission Member, United States Harris Tower & Pavilion House of Representatives 611 Ryan Plaza Drive, Suite 400 ATTN: Greg Hass, District Representative Arlington, TX 76011-8064 1411 Marsh Street San Luis Obispo, CA 93401