L-2003-104, Response to NRC Comment on Relief Request Risk Informed ISI
| ML031420461 | |
| Person / Time | |
|---|---|
| Site: | Turkey Point  |
| Issue date: | 05/14/2003 |
| From: | Jones T Florida Power & Light Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| L-2003-104 | |
| Download: ML031420461 (2) | |
Text
1 & zbn FPL L-2003-104 10 CFR 50.36 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington D. C. 20555 Re:
Turkey Point Unit 4 Docket No. 50-251 FPL Response to NRC Comment on Relief Request Risk Informed ISI By letter L-2003-001, dated January 15, 2003, FPL submitted a response to the NRC request for additional information regarding the Risk Informed Inservice Inspection (Ri-ISI) Relief Request for Turkey Point Unit 4. On March 3,2003, the NRC requested additional clarification on the subject relief request. On March 25, 2003, FPL and NRC Staff discussed the NRC request on a teleconference. The purpose of this letter is to document FPL's response to the NRC's request for additional information presented in the attachment herein.
Should there be any questions regarding this matter, please contact Walter Parker at (305) 246-6632.
Very truly yours, Terry 0. Jq(es Vice President Turkey Point Plant SM Attachment cc:
Regional Administrator, Region II, USNRC Senior Resident Inspector, USNRC, Turkey Point an FPL Group company
.j Dc
Attachment to L-2003-104 NRC Request "The licensee is requesting to perform a VT-2 examination in lieu of the volumetric examinations specified in WCAP-14572, Revision 1-NP-A, for ASME Code Class 1 socket welds classified as high safety significant. However, the staff notes that Table IWB-2500-1 of the ASME Code requires surface examination, not volumetric examination, for socket welds. Surface examination (i.e., liquid penetration examination) is an effective method for discovery of potential piping outside surface initiated flaws - of specific concern, flaws induced by low-cycle, high-bending stress thermal fatigue or external chloride stress corrosion cracking (ECSCC)."
'What considerations have been made to address the potential for external degradation and the use of surface examinations for the socket welds?"
FPL Response At the present time, Turkey Point Unit 4 has not identified any low-cycle high bending stress thermal fatigue or external chloride stress corrosion cracking (ECSCC) associated with ASME Code Class 1 socket welded segments within the RI-ISI program. There is a relatively small number of segments (11 segments) that were selected as HSS; therefore, surface examination was not included.
According to WCAP-1 4752, A-Version, Section 4.5.2, Program Monitoring, the periodic Rl-ISI updates are based on feedback or corrective actions. This includes review of individual plant and industry maintenance activities associated with repairs or replacements that could impact the RI-ISI program. As part of the feedback loop process, failure, due to new degradation mechanism considerations of significant events in the industry (on an individual plant basis), coupled with plant information, is addressed in a failure probability assessment, as required.
As part of the periodic updating process, when an active or postulated failure is identified, the RI-ISI process follows the guidance within the WCAP. Appropriate NDE requirements are applied to identify and characterize the failure mechanism.