ML20069C288

Forwards Conclusions Re Presence of Faulting on Southwest Flank of Southeast Anticline,Per 820211 Conversations. Enumerates by Data Line Bases for Statements Re Southeast Anticline Fault in Apps 2K & 2R of PSAR Amend 23

ML20069C288
Person / Time
Site:	Skagit
Issue date:	03/02/1982
From:	Spangenberg F NORTHWEST ENERGY SERVICES CO.
To:	Mallory M Office of Nuclear Reactor Regulation
References
NLN-21, NUDOCS 8203080352
Download: ML20069C288 (2)

Text

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NORTHWEST ENERGY SERVICES COMPANY P O BOX 1090

• KIRKLAND, WASHING TON 98033 March 2 1982 NLNi21

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Mr. M. W. Mallory Project Manager a% MAR 051982> 4' Licensing Branch #4 Division of Licensing, NRR s maar eem tas dy g

U. S. Nuclear Regulatory Commission Washington, D.C. 20555  %

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Attn: Mr. Ilarold Lefevre

Subject:

Puget Sound Power & Light Company Skagit/Hanford Nuclear Project, Units 1 & 2 Docket Nos. 50-522 and 50-523 Request for Additional Information

Dear Mr. Mallory:

With this letter we are sending you a copy of our conclusions regarding the presence of faulting on the southwest flank of the southeast anticline. This list of conclusions, which was informally requested by Mr. Lefevre in conversations with Jim Kearnes in Bethesda on February 11, 1982, enumerates by data line the bases for statements regarding the southeast anticline fault in Appendices 2K and 2R of the Skagit/Hanford Nuclear Project Preliminary Safety Analysis Report Amendment 23. Profiles of gravity data from lines 4B through 4F on the southeast anticline were sent to you under separate cover by the Weston Geophysical Corporation. These gravity profiles were informally requested by Dr. Ibrahim during a telephone conversation with Mr. Kearnes on February 18, 1982.

If you have any questions or require additional information, please call us.

Very truly yours, b.k.

F. A. Spangenb g Assistant Project Manager, Nuclear Attach.

ec: II. Lefevre, NRC coot g g .

• g ),),er0 s6 i 8203080352 820302 PDR ADOCK 05000522 a PDR

Attachment to NLN-21 CONCLUSIONS RE SOUTIIEAST ANTICLINE FAULT BASED ON DATA CONTAINED IN S/IINP PSAR (Amend. 23)

APPENDIX 2K AND 2R Line 3 Although the Ringold section is thinned on trend with the fault interpreted l on Lines 4A through 4C, the bedrock slope is relatively gentle (510 to j 610). Thus, there are no consistent data suggesting either the presence I

or absence of the fault. It has therefore, been conservatively assumed that the fault may extend as far to the northeast as Line 3.

Line 2 A fault is inferred to be present on the bases of relatively steep bedrock slope (810 to 1010) and thinning of the Ringold formation on trend with  ;

the fault interpreted on lines 4A through 4C. Modeling of ground magnetic l data indicates that a reverse fault dipping gently to the northeast is a permissible interpretation.

Line 1 Although there is little or no evidence for the existence of the fault on Line 1. it is inferred to be present because of its inferred existence on adjacent lines.

Line 4A A reverse fault is interpreted to be present on the basis of an anomolously thick section of Elephant Mountain basalt, sheaaing observed in core hole 125, a relatively steep bedrock surface (90 to 150), and thinning of the Ringold formation. Ground magnetic anomoly "B" is observed to be coincident with the interpreted fault. Modeling of the ground magnetic data indicates that the fault probably dips gently to the NE.

Line 4B A fault is inferred to be present on the bases of relatively steep bedrock slope (610 to 1010), thinning of the Ringold formation and the presence of ground magnetic anomoly "B".

Line 4C A fault is inferred to be present but dying out to the southeast on the bases of relatively steep bedrock slope (80), decreased thinning of the Ringold section and the presence of a subdued ground magnetic anomoly "B".

Line 4D Although Figure 2K-50 shows ground magnetic anomoly "B" on this line, this identification is extremely questionable. The fault is interpreted to be absent on this line on the basis of gentle and continuous bedrock slopes indicated by gravity.

Line 4E The fault is interpreted to be absent. None of the available data indicate the existence of a fault.

Line 4F The fault is interpreted to be absent. None of the available data indicate the existence of a fault.

SUMMARY

The fault recognized in core hole 125 on line 4A is interpreted dip gently to the northeast and to possibly be up to 4 miles in length extending from Line 3 to 4C.

This interpretation is conservative and consistent with previous statements in Appendices 2R and 2K to the S/IINP PSAR (Amend. 23).

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