ML20055H013
| ML20055H013 | |
| Person / Time | |
|---|---|
| Issue date: | 07/23/1990 |
| From: | Novak M NRC OFFICE FOR ANALYSIS & EVALUATION OF OPERATIONAL DATA (AEOD) |
| To: | Rossi C Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20055H014 | List: |
| References | |
| AEOD-E90-07, AEOD-E90-7, NUDOCS 9007250054 | |
| Download: ML20055H013 (3) | |
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. MEMORANDUM FOR; Charles E. Rossi, Director Division of Operational Events Assessment '
L Office of Nuclear Reactor Regulation l.
7 Ashok C. Thadani, Director
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- Division of Systems Technology
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Offwe of Nuclear Reactor Regulation 4
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' FROM:
Thomas M. Novak, Director.
Division of Safety Programs.
i Office for Analysis ard Evaluation l
of Operational Data j
' SUBJECT;.
EFFECT OF INTERNAL FLOODING OF NUCLEAR POWER PLANT 3 ON SAFELY-RELATED EQUIPMENT n,
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. Enclosed is an' AEOD engineering evaluation report on internal flood'ing events in the secondary containment, auxiliary building, and turbine. building of nuclear power plants i
during the period 1980 to 1989. These events have caused a loss of essential equipment of
. safety related systems that are needed for decay heat removal, plant shutdown and cooldown and sho'uld be recognized as meaningful precursors to core damage accidents. For example, the LaSalle event in 1985 was analyzed by the Accident Sequence Precursor Program with' an' estimated conditional core damage probability of 7.2 E-5.
Results of evaluation of the operational events identify errors by maintenance personnel, procedural deficiencies, and inadequate design as the key elements causing internal flooding.
I To reduce the likelihood of events such as those described in our report, licensees will need to (a) re evaluate existing flood protection to address the potential for unisolable flooding 7
and common mode flooding; and (b) review maintenance procedures and per =onnel training -
I to minimize risk of unanalyzed internal flooding events caused by single component failure
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or personnel error.
6 uWe recognize that internal flooding was identified as an. internal initiating event in the Individual Plant Examination (IPE) program. The IPE submittal guidance (NUREG-1335)
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Lincludes Appendix to NUREG-1174," Evaluation of Systems Interactions in Nuclear Power Plants," as guidance document for conducting a flooding analysis based on past NRC studies.
We believe that the information provided in the enclosed AEOD report can be used to n
provide relevant operational experience to licensees performing flooding analysis as part of g
i the IPE program.
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i The recent event (July 7,1990) at Quad Cities, Units 1 and 2, which involved inoperable floor drains in ECCS rooms caused by corroded check valves and debris buildup over years, a
U further demonstrates a need to strengthen the current maintenance program to prevent
-internal' flooding. We believe that the operational experience discussed in the enclosed report and the Quad Cities event provides a basis for an Information Notice describing problems of internal flooding..We will be glad to assist your staff to develop such a 3
document.
o Further, we note that several significant flooding events occurred during cold shutdown or refueling outage. This lends support to NRC efforts to strengthen maintenance planning and administrative control during shutdown modes.
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'If ~you have any questions regarding the report, please contact Nelson Su of my staff. Dr.
Su can be reached at x24434.
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Originalsignedby
. Thomas M. Novak, Director Division of Safety Programs Office for Analysis and Evaluation of Operational Data
Enclosure:
As stated Distribution:
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(Central Filca SRubin L
ROAB R/F GZech DSP R/F MWilliams AEOD R/F'
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NSu RSavio, ACRS l
GLanik MTaylor, EDO JRosenthal PBaranowsky, NRR L
EJordan KRaglin, TTC l
Dross TNovak VBenaroya
- See previous concurrence:
ROAB:DSP:AEOD ROAB:DSP:AEOD C:ROAB:DSP:AEOD
- AEOD NSu:mmk'
. Glanik' JRosenthal*
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CRossi, AThadani ~ c The recent event (July.7,1990) at Quad Cities, Units 1 and 2, which i olved inoperable c
floor drains in ECCS rooms caused by corroded check valves and debr' buildup over years, further demonstrates a need to strengthen the current maintenan program to prevent internal flooding. We believe that the operational experience scussed in the enclosed report and the Quad Cities event warrant an I & E Informatio otice describing problems c
of internal flooding. We will be glad to assist your staff to velop such a document.
Further, we note that several significant flooding events curred during cold shutdown or refueling outage. This lends support to NRC cfforts strengthen maintenance planning and administrative control during shutdown modes.
- lf you have any questions regarding the report, ease contact Nelson Su of my staff. Dr.
Su can be reached at x24434.
Thomas M. Novak, Director.
I Division of Safety Programs Office for Analysis and Evaluation of Operational Datt
Enclosure:
As stated Distribution:
PDR.
LS sard Central File S
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ROAB R/F ch DSP R/F Williams AEOD R/F KBlack L
NSu RSavio, ACRS GLanik MTaylor, EDO JRosenthal PBaranowsky, NRR EJordan KRaglin, TTC Dross TNovak VBenaro 2
ROAB: SP:A D.R DSP:AEOD OAB:DSP:AEOD D:DSP:AEOD NSu:m k
JRosenthal TNovak 7///
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