05000389/LER-2004-001
| Docket Num E | |
| Event date: | 03-04-2004 |
|---|---|
| Report date: | 05-03-2004 |
| 3892004001R00 - NRC Website | |
DOCKET
Description of the Event
On March 4, 2004, St. Lucie Unit 2 was in Mode 1 at 100 percent reactor power. FPL was evaluating the walkdown results for the Unit 2 control room floor fire penetration seals as part of the extent of condition reviews associated with fire penetration (EIIS:PEN] deficiencies found in the St. Lucie Unit 1 control room floor.
The majority of the control room floor penetration seals were consistent with the tested configurations. However, the conduits associated with several penetrations located within the reactor-turbine generator boards (RTGBs) were not coated with a mastic per the design detail and as tested by SouthWest Research Institute.
The control room floor fire-rated seals listed in Table 1 were declared inoperable and a fire watch was established for these areas.
Cause of the Event
The lack of mastic on these penetrations originates from initial construction during the early 1980s. The drawing installation notes and details specifically require all penetrating items be coated for a distance of one foot on both sides of the penetration. However, historically coatings were limited to non-IEEE-383 cables and not to conduits; it may not have been clear that the design required conduits to be coated. During the original construction, interpretations of design requirements that appeared minor or self-evident were not always well documented. Therefore, the cause appears to be either personnel error during the implementation of design drawings or insufficient design guidance during initial installation because change documentation was inadequate for design and QC field installation verification activities.
In order to maintain fire penetration designs and prevent inadequate documentation for changes to fire penetration design requirements and implementation instructions, FPL will revise the appropriate documents to invoke an engineering hold-point for any new or reworked penetrations to ensure the design is maintained.
Analysis of the Event
Fire barriers are discussed in Chapter 9.5A of the St. Lucie Unit 2 Updated Final Safety Analysis Report (UFSAR). The principal design objective of the fire barrier and associated penetration seals is to protect personnel and redundant equipment from the effects of postulated fires in the reactor auxiliary building, to assure the capability to achieve safe shutdown in accordance with 10 CFR 50 Appendix R and BTP 9.5-1 Appendix A. The barriers and associated penetration seals are passive devices and are part of the fire protection system.
Per NUREG-1022, "Event Reporting Guidelines 10 CFR 50.72 and 50.73," Revision 2, Section 3.2.4, missing fire barriers such that the required degree of separation for redundant safe shutdown trains is lacking are reportable as an unanalyzed condition that significantly degraded plant safety. Without supporting test documentation, the as-found penetration configurations are considered inoperable. At the time of discovery 1-hour roving fire watches for the affected areas were already in place for other reasons (and had been in place for some time). Therefore, this event was not reportable under 10 CFR 50.72, but is reportable under 10 CFR 50.73(a)(2) (ii)(B).
NU FUN 366A 11-211011
DOCKET
Analysis of Safety Significance In late September 2003, a Quality Assurance (QA) department triennial fire protection audit discovered issues with the qualifications for St. Lucie Unit 1 penetration seals. The original issue dealt with fire test qualifications for control room floor penetrations, and during the extent of condition review, an additional issue was discovered when penetration conditions did not match the approved tested configuration.
These conditions were previously reported in LER 50-335/2003-003 revisions 0 and 1. As part of the extent of condition review for the St. Lucie Unit 1 control room floor penetration issue, FPL walked down the St. Lucie Unit 2 control room.
The extent of condition review concluded that several of the St. Lucie Unit 2 control room floor RTGB penetration seals deviated from the tested configurations. These penetrations are part of barriers that provide separation between redundant trains required for safe shutdown of the plant in case of a fire. The affected fire barriers are the walls between the following fire areas:
Fire Area/Zone F/42, Control Room to the following Fire Area/Zones: B/52, Cable Spread Room and C/34, "B" Switchgear Room.
In accordance with accepted fire protection practice, the combustible fire loading of a zone can be used to judge the adequacy of the fire area barriers. Each fire loading increment of 80,000 Btu/ft2 indicates the need for an additional one-hour of fire rating for the barriers. The relative fire hazard of a zone is typically classified as low if the combustible fire loading is below 80,000 Btu/ft2, moderate if below 160,000 Btu/ft2, and high if above 160,000 Btu/ft2.
The following is a summary of the combustible loading for the affected fire area/zones:
Area/Zone � Description � Fire Loading � Rating B/52 � Cable Spread Room (CSR) � 170.6x103 Btu/ft2 � High C/34 � "B" Switchgear Room � 68.16x103 Btu/ft2 � Low F/42 � Control Room (CR) � 79.5x103 Btu/ft2 � Low The CSR has high combustible loading. The principle combustible loading for the CSR is cable insulation (138.50 x 103 Btu/ft2). The CSR has an automatic pre-action firewater suppression system actuated by a heat detection system. Ionization type smoke detection is also provided within the CSR as well as in all of the adjacent zones. These detectors initiate an alarm in the control room and locally should a fire occur.
Based upon the above, FPL's initial assessment of the subject fire stops is that they are expected to be capable of providing a sufficient barrier based upon the functionality of the fire stop (i.e., not pass fire after three hours of a ASTM E119 test) when due consideration is given to the combustible loading and/or ignition sources in the affected fire areas. Based on the above, this condition has no adverse effect on the health and safety of the public.
NINFON1355A11-201111 FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6) PAGE (3) St. Lucie Unit 2 05000389
Corrective Actions
1. Work Order (WO) � 34006556 was issued to restore the applicable fire seals to a qualified three-hour fire-rated configuration. � This work will be completed during the next fall 2004 SL2-15 refueling outage.
2. FPL will revise the 2998-B-271 penetration seal implementation instructions to ensure fire penetrations seals are installed in accordance with the appropriate design detail, as supported by an approved fire test, by adding an Engineering holdpoint in the implementation instructions. � This revision will be completed August 27, � 2004.
3. FPL will complete an inspection of the St. Lucie Unit 2 control room floor fire seals by October 29, 2004. � Any new issues identified that meet 10 CFR 50.72 or 50.73 reporting criteria will be reported as a supplement to this LER within 60 days.
Additional Information
Table 1 Inoperable Control Room Floor Penetrations FS-62-043 FS-62-054 FS-62-065 FS-62-076 FS-62-044 FS-62-055 FS-62-066 FS-62-077 FS-62-045 FS-62-056 FS-62-067 FS-62-078 FS-62-046 FS-62-057 FS-62-068 FS-62-079 FS-62-047 FS-62-058 FS-62-069 FS-62-080 FS-62-048 FS-62-059 FS-62-070 FS-62-081 FS-62-049 FS-62-060 FS-62-071 FS-62-082 FS-62-050 FS-62-061 FS-62-072 FS-62-083 FS-62-051 FS-62-062 FS-62-073 FS-62-084 FS-62-052 FS-62-063 FS-62-074 FS-62-053 FS-62-064 FS-62-075 Failed Components Identified Various field-implemented control room floor fire penetration seals qualified under SouthWest Research Institute test reports.
Similar Events Qualification Testing," documents recent fire protection penetration test qualification and installation issues with the St. Lucie Unit 1 control room floor fire penetrations.
IAC MEI $161111-21111