ML040210039
| ML040210039 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun  |
| Issue date: | 02/05/2004 |
| From: | Wang A NRC/NRR/DLPM/LPD4 |
| To: | Ridenoure R Omaha Public Power District |
| Wang A, NRR/DLPM, 415-1445 | |
| References | |
| TAC MC1386 | |
| Download: ML040210039 (5) | |
Text
February 5, 2004 Mr. R. T. Ridenoure Division Manager - Nuclear Operations Omaha Public Power District Fort Calhoun Station FC-2-4 Adm.
Post Office Box 550 Fort Calhoun, NE 68023-0550
SUBJECT:
FORT CALHOUN STATION, UNIT NO. 1 - EXEMPTION REQUEST FROM THE REQUIREMENTS OF 10 CFR PART 50, APPENDIX R, SECTION III.G.2 FOR FIRE AREA 32 (TAC NO. MC1386)
Dear Mr. Ridenoure:
By letter dated October 1, 2003, Omaha Public Power District (OPPD) withdrew the subject exemption request. OPPD stated it is currently evaluating other options to resolve the non-cited violation. By teleconference on July 29 and October 31, 2003, the staff agreed to a site visit to discuss Fire Area 32 and the fire protection requirements governing this area. By e-mail dated December 23, 2003, we provided OPPD with a list of the topics that we wanted to be discussed during this site visit. On January 13 and 14, 2004, we visited the site to discuss these topics. Enclosed is a pending list of topics that the NRC staff believes need addressing for any future licensing actions related to fire area 32.
Sincerely,
/RA/
Alan B. Wang, Project Manager, Section 2 Project Directorate IV Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket No. 50-285
Enclosure:
Discussion Topics cc w/encl: See next page
February 5, 2004 Mr. R. T. Ridenoure Division Manager - Nuclear Operations Omaha Public Power District Fort Calhoun Station FC-2-4 Adm.
Post Office Box 550 Fort Calhoun, NE 68023-0550
SUBJECT:
FORT CALHOUN STATION, UNIT NO. 1 - EXEMPTION REQUEST FROM THE REQUIREMENTS OF 10 CFR PART 50, APPENDIX R, SECTION III.G.2 FOR FIRE AREA 32 (TAC NO. MC1386)
Dear Mr. Ridenoure:
By letter dated October 1, 2003, Omaha Public Power District (OPPD) withdrew the subject exemption request. OPPD stated it is currently evaluating other options to resolve the non-cited violation. By teleconference on July 29 and October 31, 2003, the staff agreed to a site visit to discuss Fire Area 32 and the fire protection requirements governing this area. By e-mail dated December 23, 2003, we provided OPPD with a list of the topics that we wanted to be discussed during this site visit. On January 13 and 14, 2004, we visited the site to discuss these topics. Enclosed is a pending list of topics that the NRC staff believes need addressing for any future licensing actions related to fire area 32.
Sincerely,
/RA/
Alan B. Wang, Project Manager, Section 2 Project Directorate IV Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket No. 50-285 DISTRIBUTION:
PUBLIC RidsOgcRp
Enclosure:
Discussion Topics PDIV-2 Reading RidsAcrsAcnwMailCenter RidsNrrDlpmPdiv (HBerkow) SWeerakkody cc w/encl: See next page RidsNrrPMAWang CJohnson, Region IV RidsNrrLAEPeyton
- For previous concurrences see attached ORC ADAMS ACCESSION NO.: ML040210039 NRR-106 OFFICE PDIV-2/PM PDIV-2/LA SPLB/SC*
PDIV-2/SC*
NAME AWang EPeyton SWeerakkody SDembek DATE 2/4/04 2/4/04 2/2/04 1/28/04 DOCUMENT NAME: C:\\ORPCheckout\\FileNET\\ML040210039.wpd OFFICIAL RECORD COPY
Ft. Calhoun Station, Unit 1 cc:
Winston & Strawn ATTN: James R. Curtiss, Esq.
1400 L Street, N.W.
Washington, DC 20005-3502 Chairman Washington County Board of Supervisors P.O. Box 466 Blair, NE 68008 Mr. John Kramer, Resident Inspector U.S. Nuclear Regulatory Commission P.O. Box 310 Fort Calhoun, NE 68023 Regional Administrator, Region IV U.S. Nuclear Regulatory Commission 611 Ryan Plaza Drive, Suite 400 Arlington, TX 76011-4005 Ms. Sue Semerera, Section Administrator Nebraska Health and Human Services Systems Division of Public Health Assurance Consumer Services Section 301 Cententiall Mall, South P.O. Box 95007 Lincoln, NE 68509-5007 Mr. David J. Bannister, Manager Fort Calhoun Station Omaha Public Power District Fort Calhoun Station FC-1-1 Plant P.O. Box 550 Fort Calhoun, NE 68023-0550 Mr. John B. Herman Manager - Nuclear Licensing Omaha Public Power District Fort Calhoun Station FC-2-4 Adm.
P.O. Box 550 Fort Calhoun, NE 68023-0550 Mr. Daniel K. McGhee Bureau of Radiological Health Iowa Department of Public Health 401 SW 7th Street, Suite D Des Moines, IA 50309 Mr. Richard P. Clemens Division Manager - Nuclear Assessments Omaha Public Power District Fort Calhoun Station P.O. Box 550 Fort Calhoun, NE 68023-0550
DISCUSSION TOPICS REQUIREMENTS OF 10 CFR PART 50, APPENDIX R, SECTION III.G.2 FOR FIRE AREA 32 OMAHA PUBLIC POWER DISTRICT FORT CALHOUN STATION, UNIT 1 (FCS)
DOCKET NO. 50-285
Background
The following discussion represents the NRC staffs concerns with the exemption request submitted on November 8, 2002, and subsequently withdrawn on October 1, 2003. The
'showstoppers' are based on information the NRC currently has available relative to the withdrawn exemption request. The pending items below are topics that the NRC staff believes need addressing for any future licensing actions related to fire area 32.
FCS Fire Modeling Analysis Omaha Public Power District (OPPD) performed fire hazard analyses to evaluate the significance of in-situ combustibles present and anticipated transient combustibles in Fire Area (FA)-32. The in-situ combustible fire scenarios were based on a lubricant oil spill from an auxiliary feedwater pump or one of the three air compressors and the transient combustible fire scenarios were based on Class A combustibles. The fire modeling was performed using the Electric Power Research Institute's FIVE methodology. The consequences of the fire were evaluated for target damage time as well as suppression system actuation time.
The fire modeling analyses appear to show that the time it takes to detect a fire is equivalent to the time the pre-action sprinkler system actuates. Therefore, at this point, damage can occur to cables within the target distance and there is no safety margin available between the time the suppression system actuates and the time to damage. This appears to be the case for the scenarios postulated by OPPD and in at least one case (transient fire above Room 19),
damage appears to occur prior to suppression system actuation.
Based on the above, there appears to be no safety margin and defense-in-depth afforded to prevent the propagation of fire to redundant trains of equipment. For example, redundant cables located three feet apart would be damaged by a fire prior to automatic suppression actuation.
To illustrate the above concern with lack of safety margin and defense-in-depth, the following example of a fire scenario done by OPPD in FA-32 is provided. The following is an example of FCS fire modeling done in FA-32.
Scenario 2 - Large Auxiliary Feedwater Pump FW-10 Fire with Suppression Fire heat release rate (fire intensity) = 4,528 Btu/sec Fire duration = 150 sec (2.5 min)
Results Estimated time to target damage = 7 sec Estimated time to detector (sprinkler) actuation = 6.95 sec Radiative heat flux to target = 1.09 Btu/ft2-sec
The fire scenario demonstrated that the target failure heat flux of 1.09 Btu/ft2-sec exceeds damage threshold heat flux, or the radiative heat flux to IEEE-383 cables exceed the failure limit.
The difference between time to damage and sprinkler activation time is 0.05 seconds.
The margin is non-existent.
OPPDs analysis is based on all cables being thermoset. NRC Inspection Report 50-285/98-01, dated April 6, 1998, documents that many cables are not thermoset which results in fire damage at 0.5 Btu/ft2-sec.
IEEE-383 qualified and non-qualified (thermoplastic and thermoset) power and control cables mixed in trays. The FCS fire modeling analysis is based on IEEE-383 qualified cables.
A previous Region IV inspection has documented that not all cables at FCS in FA-32 are IEEE-383 qualified.
OPPD did not analyze a scenario where non-credited cables can propagate fire to credited cables.
For situations where cables are mixed in a cable tray, this allows a lower threshold for failure and ignition of IEEE-383 non-qualified cables. These cables can provide a path for ignition of adjacent IEEE-383 qualified cables which should be analyzed by OPPD.
In addition to the stated concerns regarding whether the cables are IEEE-383 qualified or non-qualified, recent testing conducted by the industry in support of the resolution for associated circuits demonstrated damage thresholds for thermoset and thermoplastic cables that are different from the IEEE-383 and non-qualified thresholds. In light of this most recent knowledge of cable failures, the fire modeling should reassess the damage to the targets using the criteria of damage thresholds for thermoset or thermoplastic cable, as appropriate for the target being evaluated. The fire modeling used in this exemption request should be consistent with up-to-date information on damage thresholds (e.g., for thermoplastic cable 0.5 Btu/ft2s and 400F; and for thermoset cable 1.0 Btu/ft2s and 625F).
Based on the above concerns with the fire modeling, the staff would not have been able to conclude that the proposed exemption request meets the underlying purpose of the rule.
In addition to the above fire modeling items, the staff recommends that the manual actions proposed by OPPD in the exemption request be preliminarily evaluated against the interim manual actions criteria published in the Federal Register notice on November 26, 2003 (68 FR 66501), to help OPPD in their analysis.