ML072750175
| ML072750175 | |
| Person / Time | |
|---|---|
| Site: | Vermont Yankee File:NorthStar Vermont Yankee icon.png |
| Issue date: | 09/13/2007 |
| From: | Conte R NRC Region 1 |
| To: | Rajender Auluck, Rowley J Office of Nuclear Reactor Regulation |
| References | |
| Download: ML072750175 (4) | |
Text
CRichard L - Conte - more info Page I1 From: Richard Conte To: Jonathan Rowley; Rajender Auluck Date: 09/13/2007 11:16:04 AM
Subject:
more info This was prepared for a separate cong. briefing.
maint. in ROP is addressed
c-c \ternp\GW}00001 TMP -
Page 1 I Mail Envelope Properties (46E95434.EFF : 13 : 55942)
Subject:
more info Creation Date 09113/2007 11:16:04 AM From: Richard Conte Created By: RJC@nrc.gov Recipients Action Date & Time nrc.gov OWGWPOOI .HQGWD001 Delivered 09/13/2007 11:16:11 AM RCA (Rajender Auluck) Opened 09/13/2007 11:23:50 AM Ilrc.gov TWGWP003,HQGWDOOl Delivered 09/13/2007 11:16:09 AM JGR (Jonathan Rowley) Opened 09/13/2007 11:36:34 AM Post Office Delivered Route OWGWPOOl .HQGWD001 09/13/2007 11:16:11 AM nrc.gov TWGWP003 .HQGWDOO1 09/13/2007 11:16:09 AM nrc.gov Files Sue Date & Time MESSAGE 43 1 09/13/2007 11:16:04AM EPW hearing sheet-rev3.wpd 18604 09/13/2007 7:01:44 AM Options Auto Delete: No Expiration Date: 09/27/2007 Notify Recipients: Yes Priority: Standard ReplyRequested: No Return Notification: None Concealed
Subject:
No Security: Standard To Be Delivered: Immediate Status Tracking: All Information
Vermont Yankee Cooling Tower Message: The focus of NRC's oversight and licensing actions regarding Vermont Yankee has been and will continue to be on safety.
- 1. Under the Reactor Oversight Process (ROP), risk significance is considered in determining the amount of inspection effort to be applied to a particular system, structure, or component.
The cooling towers at Vermont Yankee are very low risk structures, including the safety related cell.
- 2. NRC continues to independently inspect and evaluate the cause of the collapse of the non-safety cooling tower cell, in order to ensure the tower's safety-related cell will not be affected by a similar failure.
Key Points The NRC has routinely inspected the safety-related Vermont Yankee cooling tower cell under the ROP baseline inspection program. The baseline inspection procedures provide an opportunity for NRC to assess the general material condition of the cell, but they are not structural inspections.
During our review of Vermont Yankee's extended power amendment request, the NRC reviewed the structural adequacy of the safety-related cooling tower cell to ensure that the modifications that were installed to support the extended power uprate would not adversely affect the operability of the safety-related cell.
Possible Questions:
Q: What is the NRC regulatory oversight responsibility for the cooling towers?
A: The NRC has regulatory oversight responsibilities for the cooling towers under the ROP baseline inspection program, the extended power uprate, and license renewal. The ROP baseline program is a risk-informed process. While the cooling towers do not contribute significantly to overall plant risk, baseline inspections have been performed on the safety-related cooling tower cell in the last several years commensurate with its significance.
These inspections have included fire protection, equipment alignment, and operability determinations, which have provided the inspectors an opportunity to assess the general material condition of the cell. These inspections were not structural inspections. See questions below for additional information on extended power uprate and license renewal Q: What can (and have) we inspected under the maintenance rule with respect to the cooling towers?
A: When the maintenance rule was published, all licensees performed a scoping evaluation to determine what systems, structures, and components (SSCs) were subject to the maintenance rule. The Vermont Yankee cooling towers were scoped into the maintenance rule for their alternate cooling system function (which pertains only to the safety-related cell), the circulating water system function, and the buildings and structures category. The NRC has not inspected the cooling towers under the maintenance rule because of their low risk significance and historical good performance. The NRC has inspected the towers under
other baseline inspection procedures such as fire protection and equipment alignment.
Q. Entergy made modifications to the cooling towers as part of their extended power uprate (EPU) amendment. Did these modifications contribute to the cooling tower collapse and did the NRC evaluate the modifications as part the EPU license review?
A. During the NRC review of the EPU amendment request, the staff confirmed that the Alternate Cooling System (ACS), or safety-related cooling tower cell, met applicable regulatory requirements. As part of the EPU modifications, Entergy installed higher efficiency fan blades and higher horsepower motors in 21 of the 22 cooling tower cells. The safety related cell in the ACS was not modified. The NRC staff visually examined key structural elements and reviewed calculations regarding the ACS cooling tower cell. Based on this review, the NRC staff concluded that Entergy's seismic and structural evaluation adequately accounted for the cooling tower modifications which were installed to support the EPU; and that there was reasonable assurance that the cooling tower modifications, and operations under EPU conditions, would not adversely affect the ability of the ACS to perform its intended safety function following a design basis seismic event. Based on the NRC's followup of the recent event at Vermont Yankee, The NRC has not identified any new information that would call into question that conclusion.
Q: In reference to NRC's August 29, 2007 request for additional information about the validity of the licensee's renewal scoping analysis in light of the cooling tower failure, how is license renewal scoping accomplished, and how does a licensee know what to include in an application?
A. The rule 10 CFR 54.4 gives requirements as to what systems, structures and components (SSCs) are in the scope of license renewal. Related documents such as NUREG 1800 and 1801 give additional guidance in this area with respect to staff expectations and review requirements. Additionally, Regulatory Guide 1.188, dated July 2001, "Standard Format and Content for Applications to Renew Nuclear Power Plant Operating Licenses endorses an industry document NE1 95-10, Revision 3, dated March 2001, "Industry Guideline for Implementing the requirements of 10 CFR 54 - The License Renewal Rule," which gives additional guidance on how to apply for a renewed license.
Vermont Yankee's license renewal application states that the purpose of the safety-related cell (designated cell 2-1) and its associated deep basin is to provide a heat sink to remove decay heat and sensible heat from the primary system so that the reactor can be safely shut down in the event the service water pumps are not available. Cell 2-1, adjoining cell 2-2, and the deep basin support and protect structures necessary to provide the heat sink. The deep basin and the alternate cooling cell (with the adjoining cell) are seismic Class I.
In accordance with this section of the license renewal application. it should be noted that cell 2-4, the cell that collapsed, is not within scope. Cell 2-1 is within scope for its alternate cooling system function, and cell 2-2 is within scope as a non-safety structure that can affect a safety function. The rule does not require a "cascading" analysis such that cell 2-4 affects cell 2-3 which affects cell 2- 2. Therefore, no Aging Management Program is applicable to Cell 2 4.
The purpose of the RAI on August 29, 2007 was to re-affirm our understandingas noted above.