ML20134L157
| ML20134L157 | |
| Person / Time | |
|---|---|
| Site: | Quad Cities  |
| Issue date: | 01/31/1997 |
| From: | Pearce L COMMONWEALTH EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| LWP-97-008, LWP-97-8, NUDOCS 9702180313 | |
| Download: ML20134L157 (2) | |
Text
Comnuinwealth litiwn Company Quad Cities Generating Station i
22710 2tLth Avenue North (I>rdova, 11.61212#740 t
Tel 3tP>M F224 i LWP-97-008 January 31, 1997 United States Nuclear Regulatory Commission Washington, DC 20555 j
Attention: Document Control Desk
References:
(a) NRC Special Inspection Report No. 50-254/96015 (DRS);
50-265/96015 (DRS) and Notice of Deviation, dated November i
22, 1996.
Subject:
Improperly Sized Overloads Found on the Control Room Heating, Ventilation and Air Conditioning (HVAC) System in 1995 l
In Reference (a) the NRC asked:
... we are concerned about the difference between conclusions reached regarding safety significance of undersized thermal overloads identified in the Control Room Ventilation System at your facility and the Dresden facility. As a result, we request that you provide us, within sixty days of receipt of this letter, the results of a reassessment of the safety significance of this issue and the justification of differences, if any, between the two facilities."
As noted above, NRC inspectors reviewed Quad Cities Licensee Event Report (LER) 50-254/95-002, " Improperly Sized Overloads Found on the Control Room Heating, Ventilation and Air Conditioning (HVAC) System Due to Inadequate Original Design Analysis," and Dresden LER 50-237/95-001 " Inoperable Control Room HVAC Booster Fans due to Improperly Sized Thermal Overload hter Devices." During these reviews, the inspectors noted that although the event at Dresden appeared identical to the event at Quad Cities, the evaluation of the safety significance of undersized thermal overloads identified in the Control Room Ventilation System was different between the two facilities.
Quad Cities had determined that in the event of a design basis LOCA congruent with a degraded voltage condition, the "B" train of Control Room Ventilation could have failed due to the undersized thermal overloads.
If the "B" Control Room HVAC system failed, unfiltered air had the ootential to enter the control room subjecting the operators to increase dose.
The Dresden LER stated that the safety slgnificance of the event was minimal because a means was readily available for the operators to manually restart the booster fans within a reasona'le o
time period.
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LWP-97-008 U. S. NRC Page 2 January 31, 1997 4
In response to this request, Quad Cities Station has conducted a reassessment of the safety significance of the issue.
Quad Cities i
Station concluded that the safety significance, as reported in Quad Cities LER 50-254/95-002, was correct. At Dresden Station there are differences in the design.
For instance, the Control Room HVAC system included the Dresden Unit 1 Control Room. The impact of the undersized overloads was reduced because only one fan was affected.
Htvever, Dresden Station is reassessing the event and will submit a supplemental LER if that is appropriate.
If you have any questions concerning this letter, please contact Charles Peterson, Regulatory Affairs Manager, at (309) 654-2241 extension 3609.
Respectfull,
g 4
a[J O lcA L L
W. Pearce Station Manager Quad Cities Station LWP\\RL\\pim cc:
A. B. Beach, Regional Administrator, Regian III R. M. Pulsifer, Project Manager, NRR J. F. Stang, Project Manager, NRR C. M. Miller, Senior Resident Inspector, Quad Cities C. L. Vanderneit, Senior Resident Inspector, Dresden D. C. Tubbs, MidAmerican Energy Company R. J. Singer, MidAmerican Energy Company F. A. Spangenberg, Regulatory Affairs Manager, Dresden C. C. Peterson, Regulatory Affairs Manager, Quad Cities DCD License (both electronic and hard copies)
STMGR00897.L47