05000413/LER-2002-004, Re Pipe Spray Interaction Affecting Safety Related Equipment
| ML022190316 | |
| Person / Time | |
|---|---|
| Site: | Catawba  |
| Issue date: | 07/25/2002 |
| From: | Gordon Peterson Duke Energy Corp, Duke Power Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| LER-02-004-00 | |
| Download: ML022190316 (9) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(v), Loss of Safety Function |
| 4132002004R00 - NRC Website | |
text
Duke GARY R. PETERSON 9 Power Vice President f~ftwereCatawba Nuctear Station A Duke Energy Company Duke Power CNO 1 VP / 4800 Concord Rd.
York, SC 29745 803 831 4251 803 831 3221 fax grpeters@duke-energy. corn July 25, 2002 U. S. Nuclear Regulatory Commission ATTENTION:
Document Control Desk Washington, DC 20555-0001
SUBJECT:
Duke Energy Corporation Catawba Nuclear Station Units 1 & 2 Docket Nos. 50-413, 50-414 Licensee Event Report 413/02-004 Revision 0 Pipe Spray Interaction Affecting Safety Related Equipment Attached please find Licensee Event Report 413/02-004 Revision 0, entitled "Pipe Spray Interaction Affecting Safety Related Equipment."f This Licensee Event Report does not contain any regulatory
commitments
This event is considered to be of no significance with respect to the health and safety of the public.
Questions regarding this Licensee Event Report should be directed to R. D. Hart at (803) 831-3622.
Sincerely, G. R. Peterson Attachment (y
www. duke-energy. corn
U.S. Nuclear Regulatory Commission July 25, 2002 Page 2 xc:
L.
A.
Reyes U.
S. Nuclear Regulatory Commission Regional Administrator, Region II Atlanta Federal Center 61 Forsyth St.,
SW, Suite 23T85 Atlanta, GA 30303 C.
P. Patel (addressee only)
NRC Senior Project Manager (CNS)
U.
S. Nuclear Regulatory Commission Mail Stop O-H812 Washington, DC 20555-0001 D.
J.
Roberts Senior Resident Inspector (CNS)
U.
S. Nuclear Regulatory Commission Catawba Nuclear Site
Abstract
During review of a plant modification it was noted that 600 volt motor control centers (MCCs) 1EMXG and 2EMXH may not have been adequately protected from potential moderate energy spray interactions in the chilled water (YC) chiller rooms.
A section of fire protection system piping and demineralized water (YM) piping in both A and B train chiller rooms were identified as potential sources for moderate energy spray onto the MCC.
Engineering evaluated this condition and determined that MCCs 1EMXG and 2EMXH had not been adequately protected from the effects of a moderate energy pipe break associated with the YM or fire protection systems inside the Train A and B YC chiller rooms as required by the UFSAR.
Temporary spray deflectors were installed to correct the issue.
Follow up reviews by engineering determined that 4160 volt bus 2ETA was determined to be a water spray target from fire protection piping to the hose rack cabinet in the area.
Operations was notified and declared 2ETA inoperable and applied Technical Specification 3.8.9.
A spray deflector was installed and 2ETA was declared operable.
This event did not affect the health and safety of the public.
NRC FORM 366 (7-2001)
(if more space is required, use additional copies of NRC Forn 366A) (17)
BACKGROUND Catawba Nuclear Station Units 1 and 2 are Westinghouse Pressurized Water Reactors [EIIS: RCT].
The onsite Class lE AC electrical power distribution system [EIIS: EB] is divided by train into two redundant and independent electrical power distribution subsystems.
The AC electrical power subsystem for each train consists of a primary Engineered Safety Feature (ESF) 4.16 kV bus [EIIS: BU] and secondary 600 volt buses, distribution panels [EIIS: PL], motor control centers (MCCs) and load centers.
The 4.16 kV essential auxiliary power system physically consists of two independent and redundant 4.16 kV switchgear assemblies [EIIS: SWGR], designated 2ETA and 2ETB.
Each of the MCCs is single fed except 1EMXG and 2EMXH, each of which have two incoming breakers [EIIS: 52], one from a Unit 1 essential source and one from a Unit 2 essential load center.
These two incoming breakers are also Kirk-Key and electrically interlocked which prevent paralleling the two sources.
The transfer of power supply from Unit 1 to Unit 2 and vice versa is accomplished manually.
UFSAR section 3.6, Protection Against Dynamic Effects Associated with the Postulated Rupture of Piping, describes the requirements for protection against dynamic effects associated with the postulated rupture of piping.
Specifically the general design requirements for postulated piping breaks other than reactor coolant system requires that the design be of a nature to mitigate the consequences of the break so that the reactor can be shutdown safely and eventually maintained in a cold shutdown condition.
Consideration is given to the potential for a random single failure of an active component subsequent to the postulated pipe rupture.
During review of a plant modification it was noted that 600 volt MCC 2EMXH may not have been adequately protected from a potential moderate energy spray interactions in the B train chilled water (YC) [EIIS: KM]
chiller room.
It was noted that some sections of YC piping in the YC chiller rooms had spray shields installed and other sections did not.
A section of fire protection system [EIIS: KP] piping was identified as a potential source for moderate energy spray onto the MCC.
An additional field review revealed that the demineralized water (YM)
[EIIS: KC] piping in both train A and B chiller rooms could be a potential source of water spray for either 1EMXG or 2EMXH.
(If more space is required, use additional copies of (If more space is required, use additional copies of (If more space is required, use additional copies of (if more space is required, use additional copies of (If more space is required, use additional copies of NRC Forn 366A) (17)
SAFETY ANALYSIS
The Catawba PRA was used to evaluate the risk significance of the potential spray interaction.
The consequence of losing accident mitigation equipment was combined with the likelihood of having a pipe failure.
The increased probability of causing an initiating event was also considered.
The results indicated that the increase in core damage frequency is negligible.
The probability of having a pipe break is remote.
In addition, there is only a small population of unprotected piping.
These are the primary factors that lead to the conclusion that the increased risk is negligible.
In conclusion, the overall safety significance of this event was determined to be minimal and there was no actual impact on the health and safety of the public.
ADDITIONAL INFORMATION
A review of LERs from the last three (3) years found no LERs written for plant design issues concerning pipe spray interactions.
Therefore, this event was determined to be non-recurring in nature.
Energy Industry Identification System (EIIS) codes are identified in the text as [EIIS: XX].
This event did not involve an equipment failure and is not considered reportable to the Equipment Performance and Information Exchange (EPIX) program.
Although the safety significance of this issue was minimal, this condition met the reporting criteria of 10 CFR 50.73(a)(2)(v) and therefore will be recorded under the NRC Performance Indicators for both units as a safety system functional failure.
The safety systems affected are 600 volt MCCs and 4160 volt buses.
There were no releases of radioactive materials, radiation exposures or personnel injuries associated with this event.