ML20057C500
| ML20057C500 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 09/21/1993 |
| From: | Donnelly P CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9309290036 | |
| Download: ML20057C500 (4) | |
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C00SumBIS Power Patrick M Donnelly i'%
PUni Manager POWERING MKHIGAN'S PROGRESS Big Rock Point Nuclear Plant.10269 US-31 Nonh, Charlevon, MI 49720 September 21, 1993 1
Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 DOCKET 50-155 - LICENSE DPR BIG ROCK POINT PLANT - ADDITIONAL RESPONSE TO A REQUEST FOR ADDITIONAL INFORMATION WITH REGARDS TO A NUCLEAR REGULATORY COMMISSION ASSESSMENT OF THE BIG ROCK POINT'S EMERGENCY CONDENSER AND MAIN STEAM ISOLATION VALVES, DATED JUNE 29, 1993.
On August 12, 1993, Big Rock Point submitted a partial response to a Request for Additional Information with regards to a Nuclear Regulatory Commission Assessment of the Big Rock Point's Emergency Condenser and Main Steam Isolation Valves, dated June 29, 1993. The NRC requested that certain actions be taken to provide additional assurance that these valves will close as required. Of the seven actions requested, five were addressed by the Big Rock Point staff in the August 12, 1993 submittal. The facility committed to an additional response within 15 days to address the remaining actions requiring changes to current operating / emergency procedures and probable modification of valve position indication.
These actions are addressed in the response attached, and should be completed by the facility by November 15, 1993.
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Patrick M Donnelly
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Plant Manager CC: Administrator, Region III, USNRC NRC Resident Inspector - Big Rock Point ATTACHMENT 27 139 h3
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9309290036 930921 P
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4 ATTACHMENT Consumers Power Company Big Rock Point Plant Docket 50-155 DOCKET 50-155 - LICENSE DPR BIG ROCK POINT PLANT - ADDITIONAL RESPONSE TO A REQUEST FOR ADDITIONAL INFORMATION WITH REGARDS TO A NUCLEAR REGULATORY COMMISSION ASSESSMENT OF THE BIG ROCK POINT'S EMERGENCY CONDENSER AND NAIN STEAM ISOLATION VALVES, DATED JUNE 29, 1993.
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ATTACHMENT TO ADDITIONAL RESPONSE TO RAI DATED 6/29/93 1
EMERGENCY CONDENSER INLET ISOLATION VALVES MO 7052 AND MO 7062 EMEB/NRR CONCLUSION
...The staff should request the licensee to perform the following action (s) to provide assurance that the EC inlet isolaticn valves are maintained capable of isolation an EC tube break:
(3) modify the emergency procedures and position indication, if necessary, to L
ensure that MOVs closed fully following a break.
LICENSER'S RESPONSE EMEB/NRR's primary belief is, that if tested and maintained properly, the EC inlet isolation valves are sized sufficiently to isolate flow in the event of a line break. However, to address their concern that the torque switch might trip prematurely and these MOVs might need to be resignaled to close, the following items were reviewed for modification:
Emergency Procedures These procedures reference the Standard Operating Procedures with regards to the applicable event, and this is where the revision will occur.
Standard Operating Procedures A revision cautioning that should the torque switch prematurely trip, the MOVs may need to be resignaled by the operator, will be made to Standard Operating Procedure 6, Emergency Condenser System, Section 6.1.4 Isolate a Leakino Tube
- Bundle, This action is expected to be completed by November 15, 1993.
Position Indication Modification If the Emergency Condenser is the source of an uncontrolled radioactive release and requires isolating, the operators are trained to verify that the valve (s) are closed not only by position indication lights, (the closed light illuminates when the valve is 8% off its seat), but also by monitoring:
- 1) for a reduction in radiation levels (at the Emergency Condenser vent via the radiation monitoring instrument), and
- 2) for a loss / gain in primary system water inventory.
Big Rock Point's staff believes that by monitoring these parameters, full closure of MO 7052 and 7062 can be ascertained. The current requiremert for position indication as described above should not have to be modified.
MAIN STEAM ISOLATION VALVE (MSIV) M0 7050 EMEB/NRR CONCLUSION
...The staff would need to justify any modification to upgrade the MSIV as a backfit because the licensing basis for the MSIV does not include high differential pressure conditions. In lieu of processing a backfit, analysis, EMEB/NRR recommends that the licensee be requested:
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t ATTACHMENT TO ADDITIONAL RESPONSE TO RAI DATED 6/29/93 2
(3) to establish operator procedures to prevent premature attempts to close the valve prior to differential pressure being within the capability of the MSIV.
LICENSEE'S RESPONSE As documented in the August 12, 1993 response, the operator thrust output at torque switch trip is sufficient to close the valve under design-basis conditions, and shows that the installed springpack prevents potential overtorquing of the operator.
To prevent a premature attempt to close the valve at a differential pressure greater that 1500 lbs, a revision to Standard Operating Procedure 10, Containment Vessel, will caution the operator to this circumstance. This action is expected to be completed by November 15, 1993.
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