ML17354A735
| ML17354A735 | |
| Person / Time | |
|---|---|
| Site: | Turkey Point  |
| Issue date: | 11/12/1997 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML17354A734 | List: |
| References | |
| GL-95-07, GL-95-7, NUDOCS 9712150422 | |
| Download: ML17354A735 (2) | |
Text
e.
The licensee stated that, for long-term corrective action, the ComEd thrust prediction methodology was used to demonstrate that the pressurizer power-operated relief valve block valves, MOV 3/4-535/536, could open under pressure-locking conditions.
Under certain conditions, the staff finds that the ComEd methodology provides a technically sound basis for assuring that valves susceptible to pressure locking are capable of performing their intended safety-related function.
On April 9, 1997, a public meeting was held to discuss the ComEd pressure-locking thrust prediction methodology presented in licensee submittals responding to GL 95-07.
The minutes of the public meeting were issued on April 25, 1997.
At the public meeting, ComEd recommended that, when using its methodology, minimum margins should be applied between calculated pressure-locking thrust and actuator capability.
For those valves identified in this safety evaluation that use the ComEd pressure-locking thrust prediction methodology for interim and long-term corrective action, the licensee should ensure that the margin between calculated pressure-locking thrust and actuator capability meets or exceeds these minimum requirements.
At the meeting, ComEd indicated that its methodology is undergoing review and may be revised or enhanced.
The licensee is responsible for ensuring that the thrust values calculated to overcome pressure locking for these valves remain valid following implementation of any revisions or enhancements to the ComEd methodology.
The staff is reviewing the ComEd methodology and will issue a safety evaluation for the methodology.
f.
The licensee stated that all flexible and solid wedge gate valves in the scope of GL 95-07 were evaluated for thermal binding. When evaluating whether valves were susceptible to thermal binding, the licensee assumed that thermal binding would not occur below specific temperature thresholds.
The screening criteria used by the licensee appear to provide a reasonable approach to identify those valves that might be susceptible to thermal binding.
Until more definitive industry criteria are developed, the staff concludes that the licensee's actions to address thermal binding of gate valves are acceptable.
4.0 N
I N
On the basis of this evaluation, the NRC staff finds that the licensee has performed appropriate evaluations of the operational configurations of safety-related power-operated gate valves to identify valves at Turkey Point Units 3 and 4 that are susceptible to pressure locking or thermal binding.
In addition, the NRC staff finds that the licensee has taken," or is scheduled to take, appropriate corrective actions to ensure that these valves are capable of performing their intended safety functions.
Therefore, the staff concludes that the licensee has adequately addressed the requested actions discussed in GL 95-07.
Principal Contributor; S. Tingen, NRR Date:
November 12, 1997 Enclosure 9712i50422 971203 PDR ADOCK 05900250 P
~'
~ + r
~r