ML20147C891
| ML20147C891 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 03/02/1988 |
| From: | Gridley R TENNESSEE VALLEY AUTHORITY |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| NUDOCS 8803030185 | |
| Download: ML20147C891 (6) | |
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-TENNEOCEE VALLEY AUTHORITY CHATTANOOG A. TENNESSEE 374o1 SN 157B Lookout Place MAR 2 1988 U.S. Nuclear Regulatory Conunission ATTN: Document Control Desk Washington, D.C.
20555 Gentlemen:
In the Matter of-
)
Docket Nos. 50-327 Tennessee Valley Authority
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50-328 SEQUOYAH NUCLEAR PLANT (SQN) - RESOLUTION OF OPEN INSPECTION ISSUES During the NRC inspection in Knoxville, Tennessee, the week of February 15, 1988, a number of miscellaneous issues were reviewed. One of.the issues identified was the effect of changing the time step in developing roactor coolant loop (RCL) spectra, which is open pending TVA submittal of a confirmatory letter domamenting resolution of the issue. Enclosed is docutaentation of TVA's resolution of this item.
If you have any questions, please call D. L. Williams at (615) 632-7170.
Very truly yours.
TENNESSEE VALLEY AUTHORITY R. Gri ley, Dir t Nuclear Licensing and Regulatory Affairs Ecclosure cc: See page 2 L
I 8803030185 880302
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- - b-An Equal Opportunity Employer
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.. U.S. NUclose Regulatory Commission RAR' 21989 Enclosure r
cc (Enclosure):
Mr. K. P.-Barr, Acting Assistant Director-for Incpection Programs TVA Projects Division U.S. Nuclear Regulatory Commission
~ Region II 101'Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323
~Mr. G.'G'.-Zech, Assistant Director for Projects Division of TVA Projects Office of Special~ Projects.
U.S. Nuclear Regulatory Commission One White Flint, North 11555 Rockville Pike Rockville, Maryland 20852 Sequoyah~ Resident Inspector Sequoyah Nuclear Plant 2600 Isou Ferry Road Soddy Daist,. Tennessee 37379
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ENCLOSURE SEQUOYAH NUCLEAR PLMT ~
TIME STEP EFFECTS ON REACTOR COOLANT
' LOOP ATTACHED BRANCH PIPING SYSTEMS
SUMMARY
-OF ISSUE:
Duries the inspection'in Knoxville, Tennessee, the week of February 15, 1988, the NRC asked TVA to determine what-time step'and computer code were used to generate the~ reactor coolant loop (RCL) nozzle response sp3ctra.
RESPONSE
The acceleration response spectra for nozzle attachment points on the primary loop vae developed in January 1974.- EDS Nuclear, Inc., used a 0.01 second integration time step and an in-house computer program. The following discussion summarizes TVA's assessment of the at issue for the RCL spectra ~
and why it is nct a concern for the Sequoyah Nuclear Plant (SQN).
Previous evaluations of SQW building response spectra to assess the effects of
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changing the time step (from 0.01 to 0.005 seconds) have resulted in 25 to 50 percent increases'in peak accelerations in the region beyond 20 Hz.
It is reasonable to. assume that similar effects would be applicable to the RCL amplified response spectra.
TVA report CEB-80-4, R1 indicates that the RCL amplified response spectra have primary peaks beyond 20 Hz at the coolant pump (nodes 1262 and 1266) and the cold leg (node 1274). For surposes of this evaluation, these peak regions of the RCL amplified response spectra were increased 25 percent and 50 percent.
Since previous evaluations of this concern for piping inside containment demonstrated that piping stresses and pipe saport dasign loads are within design allowables, the evaluation of this issue has focused on the RCL nozzles only.
(Refer to response to IDI 3 tem D4.2-3 for previous studies.)
For the branch lines anchored at the coolant pumps and cold legs, isometrics were reviewed to identify those lines most rigidly supported in the nozzle region and, thus, most sensitive to response spectra poaks beyond 20 Hz.
Analysis problems N2-62-10R (2-inch schedule 160, seal water injection) and 0600154-08-16 (3/4-inch schedule 160, seal by-pass) were selected for evaluation of branch lines anchored at the coolant pump.
Problems l
0600104-09-05 (1 1/2-inch schedule 160, boron injection) and 0600152-09-02 (10-inch schedule 140, accumulator line) were selected for evaluation of branch lines anchored at the cold leg. A summary of the resulting anchor
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point stresses is as follows:
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x-
,v 2-l lN2-62-10Rl0600154-08-16l0600154-09-02l0600104-09-05l, l Original OBE l
l l (24) l (54) l-(Ali l (A4);l-2 25%
-l Stress'(lb/in )
l 2294 l
5937 l 3888 l 7250 l 1^67 l 1098' l l
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' Increase l
% Increase l
0 l
0.2 l 1.0 l0 l_25.0 l 0 l'
l. Resulting*
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l-l l
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i l' Stress Ratio l
0.437 l
0.472 l 0.493l 0.667l 0.224l-0.196l l Original OBE.
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l 50%
l Stress (1b/in2) l 2294 l
5937 ll3888 l:7250 l 1067'l 1098 l l
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l-l Increase l
% Increase l
0 l
0.4 l 2.0
[_0 l 50.0 l 0 l
l-Resulting*
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l l-l l
.l l
Stress Ratio l
0.437 l
0.472 l 0.495l 0.667l~0.258l 0:196l Numbers 24, 54, A1, and A4 are nozzle node' numbers 2
- Stress ratio for equation 9 upset, allowable is 1.2 Sh (18080 lb/in ),
As a result of this evaluation, three of the four selected sample problems were found to have virtually no increases in nozzle stress. The 25-and 50-percent increase for problem 060014-09-05 is not a concern due to the low equation 9 stress at the nozzie (5535 lb/in2). This eval'mtion demonstrates that the At impact is minimal on RCL nozzles. Also, the first seismic support adjacent to each nozzle was reviewed for increased support reaction (s) and found to satisfy SQN-DC-V-24.2 criteria.
-Additional considerations relating to this issue include displacements and damping. The maximum additional system displacement due to the 50 percent spectrum increase is approximately 0.009 inch. Available gaps in pipe-l supports other than anchorage points are typically in the order of 1/16-inch (0.0625").
This relieves additional stresses due to slight increases in displacement.
Further conservatism is added by consideration of damping values used for the
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Westinghouse RCL analysis. The SQN design is based on 1/2 percent and i
i percent for OBE and SSE, respectively. Similar Westinghouse deslgns have used 4 percent, This increased damping offpets the minor effects of the change in time step.
In summary, this evaluation demonstrates that the RCL attached piping and nozzles are not sensitive to a change in the integration time step for spectra development; therefore, no further evaluation is required.
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6 LICENSING 'IRANSMITTAL TO NRC
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SUMMARY
AND CONCURRENCE SHEET DUE NRC ASAP RESPONDS TO:
N/A COMPLETE RESPONSE 7 X YES
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DATE 8
7!M PREPARER'S SIGNA'IURE
-f FEES REQUIRED YES NO X (6j PROJECP/ DOCUMENT I.D.
Sequoyah Nuclear Plant (SON) - Resolution of Open Iy,pection Issue PURPOSE /
SUMMARY
This is a confirmatory letter documenting TVA's resolution of the open issue on the Reactor Coolant Loop Spectra.
PROBLEM OR DEFICIENCY DESCRIPTION N/A CORRECTIVE ACTION /COHNI'IMENT N/A CONCURRENCE
~
SIGNATURE OR NAME ORGANIZATION LETTER REFERENCE
-DATE H. L. Abercrombie SQN Site Director NAksmk
~6k\\\\%B W M. R. Harding SQN Site Licensing SMh3
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'd I k i
i r,I J. B. Hosmer DNE-SQEP
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V J. K. McCall DNE-CEB D. W. Wilson DNE-NTB INDEPENDENT VERIFICATION REQUIRED? YES NO X
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INDEPENDENT VERIFICATION PERFORMED BY DATE
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NAME/ ORGANIZATION glt/
2!2-7!d[
DATE APPROVED i
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03/01/1983 12:35 v NUC Et0R BR-KX 615 632 6794 P.04
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1 LICENSING 'IRANSMITTAL TO NRC
SUMMARY
AND CONCURRENCE SHE_ET l
DATE Di$ NRC ASAP RESPONDS T):
N/A
_ COMPLETEiRESPONSEf X_ YES
_ NO PREPARER'S SICNATURE DATE FEES REQUIRED YES NO X PROJECf/DOCUME?Tr I.D.
Sequoyah Nublear Plant (SQN) - Resolution of Open Inspectflon Issue _
PURPOSE /
SUMMARY
This is a confirr:atory letter documenting TVA:'s resolution
~
of thelopen issue on the Reactor Coolant Loop Spectr_a.
PROBLDL OR DEFICIENCY DESCRIPTION __ N/A CORRECTIVE ACTION / COMMITMENT _ N//,
l CONCURRENCE i
SIGNATURE 08 NAME ORGANIZATION LETTER REFERENCE DATE H. L. Abercrombie SON Site Director.
M. R.
4arding SQN Sito Licensing J. B.
Rosmer DN_E-SOEP i
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!/W/
g J. K. McCall DNE-CEB
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tE!I D. W. W!1 son DNE-?TTB y
INDEP$DENTVERIFICATIONREQUIRED2 YES NO 1 INDEP Dff VERIFICATION PERFORM BY DATE NAME/ORGiNI1ATION APPRO' ED DATE _
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