ML20128B584
| ML20128B584 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 01/29/1993 |
| From: | William Cahill TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| RTR-NUREG-0797, RTR-NUREG-797 TXX-93074, NUDOCS 9302030104 | |
| Download: ML20128B584 (8) | |
Text
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E 903.8 TUELECTRIC mm m J. c.hm. Jr.
January 29. 1993 a.m. s a. a r,a.a..,,
U. S. Nuclear Regulatory Commission Attn:
Document Control Desk Washington, DC 20555
SUBJECT:
COMANCHE PEAK STEAM ELECTRIC STATION (CPSES)
UNIT 2 DOCKET NO. 50 446 RE0 VEST F0tl ADDITIONAL INFORMATION HVAC DESIGN VAL 10AT10N REF:
- 1) Supplement No. 25 to NUREG 0797 Related to Operation of the Comanche Peak Steam Electric Station, Unit 2 (September 1992)
Gentlemen:
In September 1992. Reference 1 was issued and Section 1.7 identified outstanding issue 18, "HVAC Design Validation".
As a result of subsequent discussions with the NRC staff, additional information regarding this issue was requested.
The response to the request for additional information is provided in the Attachment to this letter.
If there are any questions, please call Mr. Carl B. Corbin at (?!4) 012-8859.
Sincerely, William J. Cahill.-Jr.
By :.
D. R. Woodlan Docket Licensing Manager
- CBC Attachment c-Mr. J. L. Milhoan, Region IV Mr. B. E. Holian, NRR Resident inspectors CPSES (2) 0 40$(
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j Attachment to TXX 93074 8
Page 1 of 6 RE0 VEST FOP. ADDITIONAL INFORMATION OUTSTANDINri ISSUE 18 HVAC DESIGN VAllDATION-
-(Item 6 Seismic Damping Values)
DESCRIPTION TV Electric uses 4% OBE and 7% SSE damping ratios for the design and validation of HVAC duct systems at Comanche Peak Steam Electric Station (CPSES).
The basis for 4% OBE and 7% SSE damping was documented ir. Project Technical Report PTR 008 ' Damping Values Used for Seismic Analysis of CPSES HVAC Duct Systems".
As described in PTR-008, the duct systems are i
classified as bolted structures and, theref ore, the use of 4% OBE and 7% SSE damping is in compliance with Regulatory Guide 1.61 for bolted steel structures.
The basis for categorizing the HVAC systems as bolted structures is also documented in PTR-008 and is comprised primarily of a discussion of HVAC fabrication and construction details.
PTR 008 also compares HVAC duct systems to cable tray systems and makes use of the full scale dynamic testing of cable tray systems as additional justification for 4% OBE and 7% SSE damping.
The NRC har. reviewed PTR 008 and has requested additional justification for the damping values.
The purpose of this paper is to demonstrate that the NRC has accepted 4% OBE and 7% SSE damping for.HVAC systems at other nuclear facilities in the U.S. and that the HVAC construction at Comanche Peak is.
Similar to the construction used at these other facilities.
Specifically, the duct construction at the Watts Bar Nuclear Plant (WBNP) will be compared to the duct construction at CPSES.
COMPARISON OF DUCT CONSTRUCT 10H Structural requirements of HVAC duct for the Watts Bar Nuclear Plant are described in Tennessee Valley Author.ty-Engineering -Specification Number 430-942.
In general, the fabrication requirements at WBNP are very similar to those for CPSES.
The CPSES requirements are specified in the H 2 XXXX-series detail drawings for duct fabrication.
Drawing H 2 0008-(relevant portions attached as Figures li 2, and 3) shows the details for CPSES duct-joints.
A comparative review of the WBNP design and the design details from CPSES drawing H-2 0008 shows that duct joints used at CPSES are very-similar to the joints used at WBNP.
Key attributes of the duct joints used at WBNP
-versus t e joints used at CPSES are compared below:
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e Attachment to TXX 93074 1P49e 2'of 6 61 tribute WBNP Desian CPSES Desian Connection bolt 5/16' dia.
5/16' dia.
Connection bolt 4' C to C max 4' C to C max spacing Material between Compressible gasket Compressible gasket connected duct pieces Flange type Companion angle Companion' angle Companion angle 1 1/2'x1 1/2'x1/8' 1 1/2'x1 1/2*x3/16' or-size 2*x2*x3/16' depending-on duct size and construction 1=sel' Companion flange
- 10 (approx 0.25') max Bolted using HUCK connection to duct tinners rivets bolts or welded This comparison demonstrates that the construction and installation of HVAC ducting at CFSES it very similar to that used at WBNP.
The NRC has reviewed and accepted:the use of 4% OBE and 7% SSE damping for HVAC duct system evaluation at WBNP as documented in SSER 06 for that facility. The basis for acceptance of these damping values was the use uf bolted companion angle flanges ~and the recommendation of 41_0BE and 7% SSE damping in Regulatory' Guide 1.61 for bolted steel structures.
The bolted companion angle duct-construction at CPSES is consiscent with the construction at WBNPiand the recommendations of Regulatory Guide 1.61.
It-should also be pointed out that CPSES HVAC duct-tabrication drawing H 2^
1000 specifies a limitation on maximum duct piece length.
The maximum duct ~
piece length used during the fabrication process is limited to'48 inches.
This means that, at a maximum, there is a bolted duct joint every 48 inches along the length of the duct system run.
Typical span lengths for the duct ~
system vary with duct size but are generally in the 7'-0*
to 10'*0' range.
Thus, every duct' span between adjacent supports typically has two= bolted duct joints.
in practice, consiuering field installation limitations - duct pieces are of ten-shorter than the maximum allowed length, resulting in more that two bolted connections within a duct span.
This provides additional redundancy in the damping mechanisms present within the duct system.
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SUMMARY
The HVAC duct joints used at CPSES are gasketed bolted connections.
The application of 4% OBE and 7% SSE damping for HVAC systems at Comanche Peak is consistent with NRC Regulatory Guide 1.61 recommendations for bolted steel structures.
These levels of damping have been licensed at other nuclear facilities in the U.S.
Additionally, as demonstrated in the preceding discussion, the bolted companion angle flange design ~ at CPSES is similar to the bolted joint design where these damping levels have been licensed.
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GENERIQ CPSES TR & RESPONSES CPSES IR Ol{LY ORC or STIPULATION RELATED rL YEnDoR SDAB1 FART _211E T
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ile (Corp) 24 ST G R. /J5 W (1' In1/^'rLL NOTES (FC) - First Class Mail IR - Inspection Reports NODIL -
Correspondence related to material / component acceptability.
VENDOR -
Vandor documents per STA-206 (Vendor Document Group or VETIP Coordinator).
SDAR/21s LER IR(CPSES)
IR( ALL)
X X
X ISEG X
X X
X X
ORC X
X X
X X
-X ORC also includes description letters for changes to licensing basis document.
January 20, 1993 E
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