ML20086K943
| ML20086K943 | |
| Person / Time | |
|---|---|
| Site: | Quad Cities  |
| Issue date: | 12/09/1991 |
| From: | Schrage J COMMONWEALTH EDISON CO. |
| To: | Murley T NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM), Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 9112130371 | |
| Download: ML20086K943 (3) | |
Text
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8' Ccmmonwealth Ediscn
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1400 Opus Place.
V Downers Grove, Illinois 60515 December 9,1991 l
Dr. Thomas E. Murley, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, DC 20555 Attn: Document Control Desk
Subject:
Quad Cities Station Unit 2 Modification Schedule for Resolution of Small Bore Piping Configuration Verification Program Discrepancies NB0]ockeLNoJM65
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Reference:
(a) License Event Report (LER) 91-03, Specific Points in-ACAD/ CAM Lines Exceed UFSAR.
. Allowable Stresses,-dated-January 18,1991:
- (b) L.N. Olshan to T.J. Kovach letter dated September _27,1991
Dear Dr. Murley:
As part of the Piping Conf;juration Verification Program (PCVP) at Quad Cities Station, Commonwealth Edison Company (CECO) deterc. aed that stresses at twelve points on four Atmospheric Containment Atmosphere [ ution (ACAD) and Containment Atmos heric Monitoring (CAM) lines exceeded UFSAR allowable --
stresses. This ana sis was documented as a Licensee Evant Report (LER? In Reference (a). CE o implemented immediate corrective actions by determ ning the operability of the affected piping.-' This was determined in accordance with the Dresden/ Quad Cities Piping System Operability Criteria.- This criteria was submitted to -
the NRC in August,1989, and formally approved in September,1991 (Reference (b)).
The operability criteria allows interim operation until appropriate modifications to the -
system can be implemented during the next refueling outage or sooner.
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lt Dr. Thomas E. Murley December 9,1991 The LER Identified the long term corrective action for this condition as implementation of Modifications 41-88-103 and 4-2-88-103. These modifications reconcile differences between "as built" and "as analyzed" small bore Mark I and ACAD/ CAM piping systems. The process for this reconciliation consists of system walkdowns, piping stress analyses, identification of corrective actions, and completion of the corrective actions. The walkdown for Units One and Two have been completed, and the plaing stress analyses are in arogress. The projected completion date for these ana yses is September,1992.
f additional stresses are found to be outside UFSAR allowable limits, a supplement to the original LER will be issued upon completion of the piping stress analyses.
As part of the piping stress analyses on Unit Two, CECO identified two outage-related piping modifications which resolve additional alping stress discrepancies. The first modification (Enginecting Change b otice 04-00383M) requires tile removal of valves 2-1402-7, and 2-1402-10 from lines 2-1418A-4" and 2-1418B-4",
followed by capping of the remaining pipe stubs. The second modification (Engineering Change Notice 04-00408M) requires rerouting of Line 2-2315-4"-LX; adding a alaing tee reinforcement 3ad; removing two existing pipe supports; adding two new p p ng supports; and mocifying an existing support. The engineering required to install these modifications is expected to be completed in mid-December i991.
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The purpose of this letter is to provide a schedule for the installation of these two modifications, based upon the Quad Cities Unit Two cycle eleven refuel outage (O2R11) schedule, and the criteria established in Reference (b). This criteria allows interim operations until appropriate modifications to the system can be implemented during the next refueling outage. Given that the schedule for completion of the required engineering mid-December,1991) is less than one month prior to start date for 02R11 (January 4(,1992), CECO will not be able to implement the two modifications
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during 02R11. This period of time between the completion of engineering and outage commencement (approximately three weeks) does not allow adequate time to prepare work packages and coordinate required construction activities with previously planned 1
work activities, without significantly impacting previously planned work evolutions and personne! safety, implementation of the reroute of line 2-2315-4"-LX would require the removal of ap3roximately five feet of 4" piping, installation of six feet of replacement pipin0, and oiler piping su 3 port construction directly above the HPCI turbine.
Currently, a complete overlaul of the HPCI turbine / pump assembly; replacement of the 2-2301-10 valve; and replacement of a HPCI toom cooler valve are also scheduled for the refuel outage. Each of these work evolutions willinvolve separate work crews and equipment. The referenced modification would significantly irr. pact these planned activities. The modification will require construction of extensive scaffolding directly above the HPCI turbinei This will also include an additional work crew to implement the modification. Given the limited availability of space in the HPCI room, the scaffolding and extra personnel working around and above the HPCI turbine during dissassembly and overhaul would significantly hinder all work evolutions in the room.-
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.y Dr. Thomas E. Murley December 9,1991 Removal of valves 2-1402-10 and 2-1402-7 would require isolation and draining of the affected piping in order to ensure personnel safety and preclude i
inadvertent loss of inventory.from the torus. These functions are more effectively accomplished when the torus is drained. Wiinout draining the torus, isolation of the.
piping would entall the closure of a single isolation valve between the torus and the affected piping. Isolation of systems and components normally requires a double isolation to ensure system integrity and personnel safety. Since the current outage.
schedule does not include draining the torus, implementation of the modification during O2R11 would significantly increase the potential for personnel injuries and industrial safety accidents, as well as increase the risk of draining torus inventory to the Reactor Building Basement.
Based upon the potential risks involved.with implementation of the.
modifications during O2R11 (given the short time-frame to plan work activities in.
conjunction with previously scheduled work), and the operability determination of the current configuration, CECO will install these modifications during the Unit 2 Cycle 12 -
refuel outage, scheduled to start in March,1993. - Updates regarding the status of the installation of these modifications will be provided to the Project Manager, including any revisions to the refuel outage schedule, if there are any comments or questions, please contact me at 708-515-7283..
Respectfully, 7
John L.
chrage Nuclear Licensing Administrator a
9 cc: A. Bert Davis - Regional Administrator, Rlli L.N. Olshan ~- Project Manager, Quad Cities :
T.E. Taylor - Senior Resident inspector, Quad Cities-
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