ML092730339
| ML092730339 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 09/23/2009 |
| From: | Stoddard D Virginia Electric & Power Co (VEPCO) |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 09-591 | |
| Download: ML092730339 (4) | |
Text
VIRGINIA ELECTRIC AND POWER COMPANY RICHMOND, VIRGINIA 23261 September 23, 2009 Attention: Document Control Desk Serial No.09-591 US Nuclear Regulatory Commission NAPS/MES Rev. 0 Washington, DC 20555-0001 Docket Nos.
50-338 50-339 License Nos. NPF-4 NPF-7 VIRGINIA ELECTRIC AND POWER COMPANY NORTH ANNA POWER STATION UNIT NOS. 1 AND 2 NOTIFICATION OF PLANNED REMOVAL OF SERVICE WATER EXPANSION JOINTS In accordance with Atomic Safety and Licensing Appeal Board Decision ALAB-578 (ALAB-578),
enclosed are summaries of: (1) Design Change (DC) NA-08-0145, "Service Water (SW)
Expansion Joint Eliminations - SW Valve House and SW Tie-In Vault", and (2) revisions to procedures 0-PT-112, "Category I Structures - Settlement Monitoring" and 0-PT-115, "Survey of Settlement Monitoring Points".
Six of the expansion joints currently installed on SW piping are to be removed and replaced with spool pieces in accordance with DC NA-08-0145. A summary of DC NA-08-0145 is contained in. Consequently, allowable settlement limits for the SW Valve House and SW Tie-In Vault must be reduced to ensure accumulated stresses in the piping do not exceed allowable stresses. These settlement limits are contained in procedures 0-PT-112 and 0-PT-115.
ALAB-578 requires notification of revisions to procedures 0-PT-112 and 0-PT-115 within 10 days of final approval. Pursuant to Dominion standards, the procedure revisions associated with DC NA-08-0145 must be implemented as the DC is installed and affected systems are returned to service. Procedures 0-PT-115 and 0-PT-112 will be revised once following the elimination of the expansion joints installed on the A train and again following the elimination of the B train expansion joints. The project schedule is as follows:
A header joints eliminated: October 4-10, 2009 B header joints eliminated: December 6 - 12, 2009 Specific procedure revisions are contained in Attachment 2 of this letter.
If you have any further questions, please contact PageKemp at 540-894-2295.
Sincerely, Daniel G. Stoddard, PE Site Vice President
Serial No.09-591 NAPS, Settlement, Procedure Revision Notification of Expansion Joint Removal
References:
(none)
Attachments:
(1) Summary of Design Change NA-08-0145, "Service Water (SW) Expansion Joint Eliminations - SW Valve House and SW Tie-In Vault" (2) Summary of procedure revisions to procedures 0-PT-1 12, "Category I Structures -
Settlement Monitoring" and 0-PT-1 15, "Survey of Settlement Monitoring Points" NRC Commitments made by this letter:
Allowable settlement limits on the SW Valve House and SW Tie-In Vault contained in procedures 0-PT-1 12 and 0-PT-1 15 will be reduced in accordance with Design Change NA 0145.
cc: US Nuclear Regulatory Commission Region II 101 Marietta Street, NW Suite 2900 Atlanta, Georgia 30323 NRC Senior Resident Inspector North Anna Power Station
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I Serial No.09-591 NAPS, Settlement, Procedure Revision Notification of Expansion Joint Removal ATTACHMENT 1
SUMMARY
OF DESIGN CHANGE (DC) NA-08-0145 SERVICE WATER (SW) EXPANSION JOINT ELIMINATIONS -
SW VALVE HOUSE AND SW TIE-IN VAULT Eight rubber expansion joints are currently installed in the Service Water (SW) System return headers located in the SW Tie-In Vault (SWTV) and the SW Valve House Expansion Joint Pit (SWVH). Of these, there are a total of four (4) 36" rubber expansion joints in the SWTV and two (2) 30" rubber expansion joints in the SWVH that are to be eliminated. The expansion joint are split evenly between the A and B trains.
These rubber expansion joints were installed in the SW System to accommodate potential differential settlement of the buildings, in addition to postulated differential seismic displacement of the pipes at the entrance to the SWTV and SWVH.
Plant Issues N-2005-2225 and N-2005-2299 documented an error in the design of these SW expansion joints and resultant damage to nearby pipe supports. Corrective actions were taken to prevent future damage to the supports. During the subsequent root cause evaluation for the event, it was noted that it appeared feasible to eliminate three of the four expansion joints in each SW train (i.e. replace the expansion joints with rigid piping spool pieces).
A formal review of the installation was performed and documented in Technical Report CE-0140, "A Feasibility Study for Elimination of Certain Expansion Joints in the Service Water System Piping." The report concluded that it was possible to eliminate a total of six of the eight expansion joints, three of the four per train.
The purpose of DC NA-08-0145 is to eliminate the six rubber expansion joints in the SWTV and SWVH as recommended in Technical Report CE-0140.
Serial No.09-591 NAPS, Settlement, Procedure Revision Notification of Expansion Joint Removal ATTACHMENT 2
SUMMARY
OF PROCEDURE REVISIONS TO 0-PT-1 12, "CATEGORY I STRUCTURES - SETTLEMENT MONITORING" AND 0-PT-1 15, "SURVEY OF SETTLEMENT MONITORING POINTS" Procedures 0-PT-1 12 and 0-PT-1 15 will be revised to reduce the total allowed settlement of all markers in the Service Water Valve House and Service Water Tie-In Vault. The baseline will be reset to those values obtained during the April 2009 survey and only 0.041 [feet] of additional settlement will be allowed.
Table 1 below contains data for the eight survey points affected by these procedure changes.
The April 2009 elevations will become the new baseline elevations. Only 0.041 [feet] of settlement beyond this new baseline will be allowed after the expansion joints are removed.
Table 1: Data for the eight survey points affected by procedure changes for O-PT-115 and O-PT-112 Current Current April 2009 Baseline TRM Current %
Marker Elevations Elevation Allowable of TRM Location Number
[feet]
Allowable SWVH 25 325.922 325.954 0.320 10.0%
SWVH 26 325.998 326.018 0.320 6.2%
SWVH 27 326.010 326.034 0.320 7.5%
SWVH 28 326.110 326.146 0.320 11.3%
SWTV 29 303.035 303.028 0.120 5.8%
SWTV 30 303.042 303.030 0.120 10.0%
SWTV 31 303.068 303.057 0.120 9.2%
SWTV 32 303.034 303.026 0.120 6.7%