ML18067A683
| ML18067A683 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 09/11/1997 |
| From: | Bordine T CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| IEB-93-002, IEB-93-2, NUDOCS 9709170264 | |
| Download: ML18067A683 (5) | |
Text
A CMS Energy Company September 11, 1997 U.S. Nuclear Regulatory Commission ATIN: Document Control Desk Washington, DC 20555 TllOllUI* t:. Bordlatl Manager Licensing DOCKET 50-255 - LICENSE DPR PALISADES PLANT SUPPLEMENTAL INFORMATION TO OUR RESPONSE TO NRC BULLETIN 93-02, "DEBRIS PLUGGING OF EMERGENCY CORE COOLING SUCTION STRAINERS" Palisades responded on June 3, 1993 to NRC Bulletin 93-02, "Debris Plugging of Emergency Core Cooling Suction Strainers," dated May 11, 1993. Since that response, additional information has been identified. The attachment to this letter provides that additional information. The purpose of this letter is to clarify our June 3, 1993 response and reaffirm that Palisades continues to meet the intent of NRC Bulletin 93-02.
SUMMARY
OF COMMITMENTS This letter contains no new commitments and no revisions to existing commitments.
'Manager, Licensing CC Administrator, Region Ill, USNRC.
Project Manager, NRR, USNRC NRC Resident Inspector - Palisades Attachment 9709170264 970911 PDR ADOCK 05000255 G
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- 27780 Blue Star Memorial Highway
- Covt::il, Ml 49043
- Tel: 616 764 2913
- Fax:616 764 2490
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I' CONSUMERS ENERGY COMPANY To the best of my knowledge, the content of this supplemental response to NRC Bulletin 93-02, "Debris Plugging of Emergency Core Cooling Suction Strainers," is truthful and complete.
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ThOTTiaSC. Berdine Manager, Licensing Sworn and subscribed to before me this J/ tJ day of..sl,f~ 1997.
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Alora M. Davis, Notary Public Berrien County, Michigan (Acting in Van Buren County, Michigan)
My commission expires August 26, 1999
[SEAL]
ATTACHMENT CONSUMERS ENERGY COMPANY PALISADES PLANT DOCKET 50-255 SUPPLEMENTAL INFORMATION TO THE PALISADES RESPONSE TO NRC BULLETIN 93-02, "DEBRIS PLUGGING OF EMERGENCY CORE COOLING SUCTION STRAINERS" 2 Pages
SUPPLEMENTAL INFORMATION - PALISADES PLANT-NRC BULLETIN 93-02, "DEBRIS PLUGGING OF EMERGENCY CORE COOLING SUCTION STRAINERS" EXECUTIVE
SUMMARY
The Palisades' response to NRC Bulletin 93-02 stated that all of the fibrous filters inside containment during operation were designed to withstand a postulated Loss Of Coolant Accident (LOCA). A subsequent review discovered the filter elements installed in the containment air coolers were not procured to the original purchase specifications and were not rated for the temperatures of the LOCA environment. The filter media binder used is water soluble at elevated temperatures and could break down.
However, some filter breakdown was recognized in the original purchase specifications as a reinforcing screen was designed and installed in the filter outlet. The fibrous filter material would not have made its way to the containment sump and emergency core cooling suction strainers due to the filter grid bars and the finned cooling coils. Prior to startup from the 1996 Refueling Outage in December 1996, the filters were replaced with filters designed to withstand the LOCA environment.
DESCRIPTION The Palisades June 3, 1993, response to NRC Bulletin 93-02, stated that "The containment general arrangement drawings were reviewed to identify any equipment which used temporary or non-LOCA designed fibrous filter or insulation material during operation. No such usage was identified."
The original review of NRC Bulletin 93-02 in May 1993 identified the use of fibrous filters in the iodine removal fans and the containment air coolers.- The original purchase documents were used to determine that the fibrous filters installed in the iodine removal fans and containment air coolers were qualified to Loss of Coolant Accident conditions. Subsequently, in November 1996, it was discovered that the containment air cooler filters (VF-1, 2, 3, 4) in service were not rated for the temperatures during a LOCA. This was discovered during a routine review of an industry operating experience report (OE 7802) and a coincident review of a 1996 Refueling Outage planned preventive maintenance activity (PPAC CRS-001) on our containment air cooler filter replacement.
It was determined that the American Air filter pad Type AG-28, installed in the 1995 refueling outage and scheduled to be replaced the 1996 refueling outage, was rated at 175 °F and was water soluble at elevated temperatures. The filter media binder agent used was also water soluble at elevated temperatures and was susceptible to breakdown. The original purchase specifications specified maximum design conditions as 283 °F, air-steam mixture and specified the filter media to be fiberglass with a phenolic binder.
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SUPPLEMENTAL INFORMATION - PALISADES PLANT - NRC BULLETIN 93-02, "DEBRIS PLUGGING OF EMERGENCY CORE COOLING SUCTION STRAINERS" The original selection of filter type was specified by Bechtel with an awareness that some filter media may come loose during accident conditions. Bechtel specified inclusion of a small grid bar arrangement down stream of the filters to reinforce the filters and to minimize the possibility that fragments of the filter will separate and clog the coil.
The function of these filters as described in FSAR Section 6.3.2.1 is to maintain cleanliness of the containment air cooler coils.
SAFETY IMPLICATIONS The use of non-LOCA rated filters for the limited time period did not change the conclusions of our June 3, 1993 response to NRC Bulletin 93-02. A breakdown of the non-LOCA rated filters would not result in the plugging of the emergency core cooling suction strainers. The containment air cooler filter's fibrous material would be stopped by both the filter grid bars and the finned cooling coils preventing their migration to the containment sump.
PRESENT CONDITION The containment air cooler filters were replaced with LOCA qualified filters prior to the return of the plant to power operation from the 1996 refueling outage.
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