ML20141M289
| ML20141M289 | |
| Person / Time | |
|---|---|
| Site: | Catawba  |
| Issue date: | 07/31/1992 |
| From: | Tuckman M DUKE POWER CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| IEB-88-008, IEB-88-8, NUDOCS 9208110052 | |
| Download: ML20141M289 (2) | |
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)brk,SC 3745 (803)MId4?6fu DUKEPOWER July 31,1992 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington D. C. 20555
Subject:
Catawba Nuclear Station, Units 1 & 2 Docket Nos. 50-413 and 50-414 NRC Bulletin 88-08 Thermal Stresses in Piping Connected to the Reactor Coolant System In a letter dated September 13, 1991 from M. S. Tuckman to the NRC, Duke reponed that it would provide an update of the status of NRC Bulletin 88-08. As referenced in previous correspondence, Duke has identified the high pressure injection lines on Catawba and McGuire Nuclear Stations as susceptible to thermal phenomena described in the bulletin. These lines at McGuire unit 2 were subsequently monitored for temperature in conjunction with other plant parameters to refine thermal loading conditions for use in the re-qualification of this piping. Based on the similarities between Catawba and McGuire, the Catawba lines wem considered to be enveloped by the preliminary analyses perfonned on McGuire.
Funher review of the high pressure injection lines at Catawba indicated that these lines are not susceptible to the phenomenon described by the bulletin, This conclusion was based on the geometry of the piping. The Catawba lines are significantly different from the McGuim piping (where cycling and stratification have been confirmed) in that:
a.
For these lines, there are no check valves located immediately off the Reactor Coolant Loop.
The distance to the first check valve from the. Reactor Coolant Piping is at least 13 feet.. This relates to a minimum distance / pipe diameter of 80 compared to a value of 25 detennined critical by Enclosure 1 of NRC letter to M. S. ~ Tuckman from T. A. Reed and R. E. Manin dated September 17,1991 entitled " Evaluation Criteria for Responses to NRC Bulletin 88-08, Action 3 and Supplement 3".
b.
The distance between the Reactor Coolant I4op Piping and the first check valve is primarily venical. The venical riser in the piping attenuates thermal stratification / -
cycling in that the hot water of the coolant loop remains at the top of the riser and the cooler fluid of the high pressure injection system remains at the bottom of the riser, f$001knoh o 0 3
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U. S. Nuclear Regulatory Cornmission July 31,1992 Page 2 For these reasons, the high pressure injection lines at Catawba have been excluded fmm further evaluation relating to NRC Bulletin 88 08. Furthennore, Duke considers NRC Bulletin 88-08 closed for Catawba Nuclear Station.
Please call C. R. lewis at 831-3076 if you have any questions.
Very tru ',yot s, M.5. k h1. S. Tuckman 4
S. D. Ebneter Regional Administrator, Region II I
R. E. hiartin, ONRR W. T. Orders Sr. Resident Inspector J
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