ML031680441
| ML031680441 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 06/14/2003 |
| From: | Salas P Tennessee Valley Authority |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| Download: ML031680441 (3) | |
Text
June 14, 2003 10 CFR 50.50(a)(3)(ii)
U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555 Gentlemen:
In the Matter of Docket No. 50-327 Tennessee Valley Authority SEQUOYAH NUCLEAR PLANT (SQN) - UNIT 1 - SUPPLEMENTAL INFORMATION FOR REQUEST FOR RELIEF FROM AMERICAN SOCIETY OF MECHANICAL ENGINEERS (ASME) CODE FOR REPLACEMENT OF ASME CODE CLASS 3 PIPING
Reference:
TVA letter to NRC dated June 14, 2003, Sequoyah Nuclear Plant (SQN) - Unit 1 -
Request for Relief from American Society of Mechanical Engineers (ASME) Code for Replacement of ASME Code Class 3 Piping This letter provides supplemental information that supports TVAs request for relief from the referenced letter. The supplemental information provides clarification of two issues related to hardship and acceptance criteria as requested by the staff during a telephone conference call on June 14, 2003.
With regard to hardship, as TVA indicated in the conference call, previous TVA experience has shown that this repair activity requires careful planning because isolation of the effected piping for the ERCW system effects dual unit operation. The initial planning for the prior ERCW system repair activity required 71 hours8.217593e-4 days <br />0.0197 hours <br />1.173942e-4 weeks <br />2.70155e-5 months <br /> of the 72 ERCW hour Limiting Condition for Operation (LCO). A team studied the schedule and was able to reduce the durations of draining the system and welding time in addition to including a design change to allow removal of a support hanger outside the LCO
U.S. Nuclear Regulatory Commission Page 2 June 14, 2003 time. The final schedule established was 47 hours5.439815e-4 days <br />0.0131 hours <br />7.771164e-5 weeks <br />1.78835e-5 months <br />. The work was performed an around the clock schedule and approximately 30 craftsmen and supervisors were involved. The team had developed several contingencies in the event a water tight boundary could not be achieved for welding the replacement piping into the system. Spare tools and equipment were secured.
For the condition of the subject request, the present level of planning has determined that the 8 inch pipe is available, however, a drain plan and contingency for leaking boundary valves has not been completed and options for freeze seal or adding drains to the pipe via hot taps are being evaluated.
The freeze seal vendor has been contacted and at least 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> mobilization will be required. In both cases, engineering support will be required.
At the time this condition was identified, the modification organization had been demobilized from the outage and specialty tools, equipment and personnel were not confirmed available. Therefore, TVA does not have the conditions considered critical for effective repair with the constraints of the LCO.
The development of contingencies to handle boundary leakage are considered critical since the initial installation of the system will require entry into multiple LCO action statements for both units. For example, LCOs 3.7.3, 3.5.2, 3.6.2.1, 3.7.15, and 3.7.1.2.
Additionally, this repair will require an engineering evaluation, to assess a small section of piping interfering with adjacent cable tray supports. The location of the pipe leak is in a very congested area of the elevation 669 ceiling, other piping, electrical cable trays, ventilation duct work and concrete walls. The evaluation is expected to take 1 week.
U.S. Nuclear Regulatory Commission Page 3 June 14, 2003 Should the planning reveal that a small section replacement is not achievable, the 8-inch line will have to be relocated.
This will entail rerouting approximately 60 feet of piping.
Based on the above, TVA considers undue hardships with a compensating increase in the level of quality and safety exist that warrant deferring the repair of the class 3 ERCW pipe. Until TVA is able to complete a degree of planning, securing of key personnel and equipment, and the development of compensatory action, commensurate with the previous experience, implementation of the repair could challenge continued operation of Unit 2.
Also during the telephone conference call, TVA explained what actions would be taken as part of TVAs commitment for conduction weekly walkdowns and assessing operability of the system. The following describes TVAs revised commitment for assessing system operability:
Engineering will perform a weekly walkdown and assess the condition of the system. If step changes (e.g., from a few drops per minute to a steady stream) in leak rate occur, additional NDE will be performed and structural integrity and operability will be evaluated. If structural integrity can not be demonstrated, appropriate actions will be taken as required by Technical Specifications.
This letter is being sent in accordance with NRC RIS 2001-05.
If you have any questions about this change, please telephone me at (423) 843-7170 or J. D. Smith at (423) 843-6672.
Sincerely, Original signed by:
Pedro Salas Licensing and Industry Affairs Manager cc: Mr. Michael L. Marshall, Jr., Senior Project Manager U.S. Nuclear Regulatory Commission Mail Stop O-8G9A One White Flint North 11555 Rockville Pike Rockville, Maryland 20852-2739