05000483/LER-2002-009, Flooding of Security Facilities on 05/12/2002
| ML021710109 | |
| Person / Time | |
|---|---|
| Site: | Callaway  |
| Issue date: | 06/11/2002 |
| From: | Witt W AmerenUE |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| ULNRC-04678 LER 02-009-00 | |
| Download: ML021710109 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| 4832002009R00 - NRC Website | |
text
PO Box 620 Fulton, MO 65251 June 11, 2002 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Mail Stop P1-137 Washington, DC 20555-0001 wAmeren UE ULNRC-04678 Gentlemen:
DOCKET NUMBER 50-483 CALLAWAY PLANT UNIT 1 UNION ELECTRIC CO.
FACILITY OPERATING LICENSE NPF-30 LICENSEE EVENT REPORT 2002-009-00 Flooding of Security Facilities The enclosed licensee event report is submitted in accordance with 10CFR73.71 (b)(1),
reporting of safeguards events described in paragraph l(c) of Appendix G, to report flooding of Security facilities that impacted the Security Plan.
Warren A. Witt Manager, Callaway Plant WAW/ewh Enclosure a subsidiary of Ameren Corporation Union Electric Cal/away Plant
ULNRC04678 June 11, 2002 Page 2 cc:
Mr. Ellis W. Merschoff Regional Administrator U.S. Nuclear Regulatory Commission Region IV 611 Ryan Plaza Drive, Suite 400 Arlington, TX 76011-8064 Senior Resident Inspector Callaway Resident Office U.S. Nuclear Regulatory Commission 8201 NRC Road Steedman, MO 65077 Mr. Jack N. Donohew (2 copies)
Licensing Project Manager, Callaway Plant Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Mail Stop 7E1 Washington, DC 20555-2738 Manager, Electric Department Missouri Public Service Commission PO Box 360 Jefferson City, MO 65102 Mr. John O'Neill Shaw, Pittman, Potts & Trowbridge 2300 N. Street N.W.
Washington, DC 20037 Records Center Institute of Nuclear Power Operations 700 Galleria Parkway Atlanta, GA 30339 Mr. Scott Bauer Regulatory Affairs Palo Verde NGS P. 0. Box 52034, Mail Station 7636 Phoneix, AZ 85072-2034 Mr. Scott Head Supervisor, Licensing South Texas Project NOC Mail Code N5014 P.O. Box 289 Wadsworth, TX 77483 Mr. Dennis Buschbaum Comanche Peak SES P.O. Box 1002 Glen Rose, TX 76043 Mr. Pat Nugent Supervisor, Licensing Pacific Gas & Electric Mail Stop 104/5/536 P.O. Box 56 Avila Beach, CA 93424
Abstract
On 5/12/02, Callaway Plant experienced heavy rainstorms (approximately 1.7 inches of rain between 1200 and 2359, 5/12/02, as recorded by plant computer) which caused flooding to occur in the Main Access Facility (MAF). At 2247, 5/12/02, an audible sump alarm annunciated in the Central Alarm Station (CAS). At 2251, water was observed to be coming up out of the floor drains. At 2333, power was lost to the CAS Security Computer monitors. Alarm annunciation was verified in the Secondary Alarm Station (SAS). At 2341, SAS entered Independent Mode, due to flooding in CAS (approximately 1.5 inches). At 2346, CAS was evacuated due to personnel safety concerns with submerged electrical components. Safeguards information and contingency gear were relocated to secure areas. Access to CAS was controlled at all times.
A one-hour notification was made to the NRC at 0039, 5/13/02, due to reduced effectiveness of the Security Plan.
The causes of the flooding were faulty sump pumps located in manholes containing conduits connected to MAF, missing waterproof conduit seals on connecting conduits, and malfunctioning sewage pumps for MAF. Repairs are being performed on the faulty sump and sewage pumps to prevent future abnormal water accumulation. Waterproof conduit seals are being replaced as necessary, to prevent unrestricted water flow into MAF.
NRC FORM 366 (7-2001)
(If more space is required, use additional copies of SUMMARY OF THE EVENT, INCLUDING DATES AND APPROXIMATE TIMES On 5/12/02, Callaway Plant experienced heavy rainstorms (approximately 1.7 inches of rain between 1200 and 2359, 5/12/02, as recorded by plant computer) which caused flooding to occur in the Main Access Facility (MAF). At 2247, 5/12/02, an audible sump alarm annunciated in the Central Alarm Station (CAS). At 2251, water was observed to be coming up out of the floor drains. At 2333, power was lost to the CAS Security Computer monitors. Alarm annunciation was verified in the Secondary Alarm Station (SAS). At 2341, SAS entered Independent Mode, due to flooding in CAS (approximately 1.5 inches). At 2346, CAS was evacuated due to personnel safety concerns with submerged electrical components. Safeguards information and contingency gear were relocated to secure areas.
Access to CAS was controlled at all times.
A one-hour notification was made to the NRC at 0039, 5/13/02, due to reduced effectiveness of the Security Plan.
The cause of the flooding of CAS was due to three items that combined to prevent adequate water removal from CAS:
- 2) Lack of waterproof conduit sealant in conduits connecting CAS and various manholes.
- 3) Faulted sewage pumps and level switches located in the Main Access Facility (MAF) and designed to control any liquid influents to CAS.
Repairs are being performed on the faulty sump and sewage pumps to prevent future abnormal water accumulation.
Waterproof conduit seals are being replaced as necessary, to prevent unrestricted water flow into MAF.
E. METHOD OF DISCOVERY OF EACH COMPONENT, SYSTEM FAILURE, OR PROCEDURAL ERROR The faulty manhole sump pumps had been identified as inoperative and were awaiting replacement. The missing waterproof conduit seals had previously been identified and rework was scheduled to begin on 5/13/02 dayshift.
The malfunctioning sewage pumps were identified when they failed to control level in the sump during the flooding event.
(If more space is required, use additional copies of NRC Form 366A) (17)
II.
EVENT DRIVEN INFORMATION A. SAFETY SYSTEMS THAT RESPONDED Not applicable to this event.
B. DURATION OF SAFETY SYSTEM INOPERABILITY
Not applicable for this event.
C. SAFETY CONSEQUENCES AND IMPLICATIONS OF THE EVENT.
There were no safety-related system affected by this event, thus there were danger to the health or safety of the public.
Ill.
CAUSE OF THE EVENT
A root cause analysis was performed and it was determined that the primary cause of this event was inadequate planning of work packages involving the affected conduits. A lack of instructions to install waterproof conduit seals upon completion of work led to the uncontrolled influx of water into MAF. Contributing causes were delayed replacement of the manhole sump pumps because like kind replacements were unavailable, and ineffective previous repairs on the sewage pumps.
IV.
CORRECTIVE ACTIONS
The following actions have been taken to keep water from entering and/or backing up into MAF:
- 1) The affected manhole sump pumps were replaced under planned work requests by 5/14/02.
- 2) Repairs have been scheduled on open conduit seals connected to MAF.
- 3) Plant employees have been directed to pump down affected manholes on a daily bases, with written instructions to contact appropriate personnel should rain occur during backshift or weekends to pump down manholes.
Additional corrective actions to address inadequate planning of work packages are under consideration.
V.
PREVIOUS SIMILAR EVENTS
A search of data covering the three-year period between 5/12/99 and 5/12/02 revealed one Corrective Action Request (CAR) written on 5/8/02 addressing the water leaking from unsealed conduits in MAF.
VI.
ADDITIONAL INFORMATION
The system and component codes listed below are from the IEEE Standard 805-1984 and IEEE Standard 803A-1984 respectively.
System(s):
WH, WK, NA Component(s):
CND, P