05000390/FIN-2008002-03
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Finding | |
|---|---|
| Title | Failure to Ensure Adequate Design and Testing of RHR Flow Limiters |
| Description | The inspectors identified an unresolved item (URI) for failure to properly control the design of devices affecting the function of the RHR Flow Control Valves. This URI will remain unresolved pending additional inspection to determined if a violation of regulatory requirements occurred. Description: On March 14, 2008, inspectors observed the licensee preparing the RHR System for mid-loop operation. Procedure GO-10, Reactor Coolant System Drain and Fill Operations, Appendix Q requires flow limiting devices to be installed on both the RHR Heat Exchanger Bypass Valve, 1-FCV-32 and RHR Heat Exchanger Outlet Valve, 1-FCV-16 for A train. The purpose of these devices is to limit RHR flow in the event of a loss of nonsafety related instrument air, thus causing pump cavitation and potential air binding of the RHR pumps at mid-loop. Communications between field personnel installing the devices and the Control Room Operators indicated that they were experiencing difficulty configuring the devices. Later reports indicated that two devices had been installed on the bypass valve and one was removed. Based on the wording in Appendix Q which says in step one to FABRICATE blocking devices suitable for application to the operators of the applicable valves on the operating train (similar to Figure 1) and the apparent difficulty with the installation, the inspectors asked if the valves were to be opened such as to engage the blocking devices to ensure actual flow was not higher than expected. Control room personnel indicated that there was no plan to do this. Inspectors questioned the basis of not verifying the functionality of the devices, and the control room personnel agreed to raise flow on each valve until the flow limiter blocked further increase. The bypass valve was tested first by raising flow to the limiter, then reducing flow below the initial flow and that back to the desired flow. The bypass valve functioned as expected. A similar test on the outlet valve proceeded smoothly until the Operator attempted to raise the flow back to the original flow. The Operator was unable to raise flow back to the original flowrate. The devices were removed, but later reinstalled and mid-loop operations continued. Inspectors went into the 1A RHR Heat Exchanger Room to observe these devices as they were being reinstalled. The devices were similar to the drawing in Appendix Q in terms of function, but not much so in terms of fit and form. Appendix Q shows a 2 inch outside diameter cylinder with a 7/8 inch, axial hole and three holes on each side drilled into the device for six bolts, with length to be determined in the field (i.e. sufficiently long to limit to the desired flow). The actual devices observed, appeared to be a length of pipe split axially, and held on the actuator stem with a single center mounted hose clamp. The operator had some difficulty installing them due to rubber gloves and due to the fact that the wall of the pipe was thin and difficult to hold aligned while the hose clamp was tightened. Analysis: The finding is more than minor because it is associated with the design control attribute of the Mitigating Systems Cornerstone and adversely affected the cornerstone objective to ensure that modifications of systems did not increase the likelihood of a loss of decay heat removal. Enforcement: An unresolved item was identified pending additional inspection to determine if a violation of regulatory requirements occurred. This unresolved item is identified as URI 50-390/2008002-03, Failure to Ensure Adequate Design and Testing of RHR Flow Limiters |
| Site: | Watts Bar  |
|---|---|
| Report | IR 05000390/2008002 Section 1R20 |
| Date counted | Mar 31, 2008 (2008Q1) |
| Type: | URI: Green |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71111.2 |
| Inspectors (proximate) | R Monk J Rivera-Ortiz W Loo H Gepford R Chou M Pribish A Rogers M Coursey R Neaser Monke Guthrie M Pribish C Peabody |
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Finding - Watts Bar - IR 05000390/2008002 | |||||||||||||||||
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Finding List (Watts Bar) @ 2008Q1
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