05000289/LER-2003-001, From Three Mile Island, Unit 1 Regarding Control Room Habitability Boundary Ventilation Access Panel Found Open Due to Latching Mechanisms Not Properly Closed
| ML032390619 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 08/20/2003 |
| From: | George Gellrich AmerGen Energy Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 5928-03-20168 LER 03-001-00 | |
| Download: ML032390619 (6) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(ii) 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2) 10 CFR 50.73(a)(2)(viii) 10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2)(iii) 10 CFR 50.73(a)(2)(iv), System Actuation 10 CFR 50.73(b)(2)(ii) |
| 2892003001R00 - NRC Website | |
text
AmerGen SM AmerGen Energy Company, LLC Telephone: 717-944-7621 An Exelon/BTitish Energy Company Three Mile Island Unit 1 Route 44i South, P.O. Box 480 Middletown, PA 17057 August 20, 2003 5928-03-20168 10 CFR 50.73 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C. 20555 THREE MILE ISLAND NUCLEAR STATION, UNIT I (TMI-1)
OPERATING LICENSE NO. DPR-50 DOCKET NO. 50-289 SUBJECT: LICENSEE EVENT REPORT (LER) NO. 2003-001-00 "CONTROL ROOM HABITABILITY BOUNDARY VENTILATION ACCESS PANEL FOUND OPEN DUE TO LATCHING MECHANISMS NOT PROPERLY CLOSED' This letter transmits LER No 2003-001-00 regarding a ventilation access panel in the Control Building habitability ventilation envelope that was discovered in the open position.
The cause of this event was that the latching mechanisms were not properly closed. For a complete description of the evaluated condition, refer to the text of the report provided on Forms 366 and 366A.
This report is being submitted in accordance with 10 CFR 50.73 (a)(2)(ii), 10 CFR 50.73 (a)(2)(v) and 10 CFR 50.73 (a)(2)(vii). For this event, the overall safety significance was minimal and there was no actual impact on the health and safety of the public. For additional information regarding this LER contact Adam Miller of TMI Unit 1 Regulatory Assurance at (717) 948-8128.
Sincerely, George. Gellrich Plant Manager GHG/awm ATTACHMENT: List of Regulatory Commitments cc:
TMI Senior Resident Inspector Administrator, Region I TMI-I Senior Project Manager File No. 03056
a SUMMARY OF AMERGEN ENERGY CO. L.L.C. COMMITMENTS The following table identifies commitments made in this document by AmerGen Energy Co. L.L.C.
(AmerGen). Any other actions discussed in the submittal represent intended or planned actions by AmerGen. They are described to the NRC for the NRC's information and are not regulatory
commitments
COMMITMENT
COMMITTED DATE OR "OUTAGE" Surveillance and Maintenance procedures for safety related ventilation 09/30/03 systems will be reviewed to identify any access panels in safety related ventilation systems that are periodically opened. The associated, readily accessible latching mechanisms will be inspected and verified properly closed.
Surveillance and Maintenance procedures for safety related ventilation 03/15/04 systems that require access panels in safety related ventilation systems to be periodically opened will be revised. The revision will add steps to verify the latching mechanisms are properly closed.
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION Estimated burden per response to comply with this mandatory Information collection request: 50 hrs. Reported lessons learned are incorporated Into LICENSEE EVENT REPORT (LER) the licensing process and fed bacgtl Industry.
roiard comments regarding burde nestimate to the Records Management Branch (T-6 F33). U.S. Nudlear (See reverse for required number of 2055 OW1, and to the Pa5ewo
{See revers for requied number o ReductionProLect.(3150.0104>, Olffce of Management and Bde digits/characters for each block) washingRCtor, LA.. £U~U.
if nforman collection does ot playo end a person Is not required to respond to. the information collection.
FACILITY NAME (1)
DOCKET NUMBER (2)
IPAGE (3)
Three Mile Island, Unit 1 05000289 l
1 OF 4 WME (4)
CONTROL ROOM HABITABILITY BOUNDARY VENTILATION ACCESS PANEL FOUND OPEN DUE TO LATCHING MECHANISMS NOT PROPERLY CLOSED EVENT DATE (5)
LER NUMBER (6)
REPORT DATE 7)
OTHER FACILITIES INVOLVED (8)
SEUENFACIY NAME DCKET NUMBER MONTH DAY YEAR YEAR NUMBER NUMBER MONTH DAY YEAR FACILITY NAME DOCKET NUMBER 06 24 2003 2003 001 --
00 08 20 2003 OPERATING THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR 5: (Check one or more) 11 I MODE N
__ 20.2201 (b) l 20.2203(a)(2)(v) l 50.73(a)(2)(l) 50.73(a)(2)(viii)
POWER 100 20.2203(a8)1) 20.2203(a)(3)(0)
X I 50.73(a)(2)(i) l l50.73(a)(2)(x4 LEVEL (10) 100 20.2203(a)l2)(i) l 20.2203(a)(3)(ii) l50.73(a)(2)(iii) 73.71 20.2203(a)(2)(ii) 20.2203(a)(4) 50.73(a)(2)(iv) l OTHER 20.2203(a)(2)(iii) 50.36(c)(1)
X 50.73(a)(2)(v)
Specify in Abstract below 20.2203(a)(2)(ivl 50.36(c)(2)
X 50.73(a)(2)(vii) or in NRC Form 366A UCENSEE CONTACT FOR THIS LER 12)
NAME TELEPHONE NUMBER include Arm Code)
Adam W.Miller of TMI-1 Regulatory Assurance (717) 948-8128 rnMPI Fm INF I IM FI1R FAF t14 MPONFN,&1 IR E;RnINTSRFPtRT I I1 REPORTABLE REPORTABLE
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SYSTEM COMPONENT MANUFACTURER TO EPIX
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IIII 1QllPPI-FFAE=AU REP RT FXP=r-T~n EXPEC E D MONTH AY CYETR lIt yel, comllete EXPECTED SUBMISSION DATE).
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I X INIO I
DATE (116 1
1 ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines) (16)
On June 24, 2003, at approximately 0630 hours0.00729 days <br />0.175 hours <br />0.00104 weeks <br />2.39715e-4 months <br /> while TMI-1 was operating at 100 percent power, an access panel in the Control Building Ventilation system was discovered in the open position. This condition would have resulted in not meeting the design basis requirement of maintaining a positive pressure Inside the Control Building Envelope (CBE) following a design basis accident. This condition was determined to be reportable in accordance with 10 CFR 50.72 (b)(3)(ii)(B) and 10 CFR 50.72 (b)(3)(v)(D). The NRC Operations Center was notified on June 25, 2003 at 1945 hours0.0225 days <br />0.54 hours <br />0.00322 weeks <br />7.400725e-4 months <br />.
The access panel was promptly closed, and the latching mechanisms were verified to be properly closed. The System Engineer walked down 45 accessible access panels within the Control Building. Two additional panels were found with one of the two latches loose (access panels were still closed). The loose latches were properly closed. The cause of this event has been determined to be that the spiral cam-type latching mechanisms were not properly closed.
There were no adverse safety consequences associated with this event, since the Control Building Ventilation system was not required to be placed in the emergency recirculation configuration at any time while the access panel was open.
Surveillance and Maintenance procedures for safety related ventilation systems that require access panels in safety related ventilation systems to be periodically opened will be revised. The revision will add steps to verify the latching mechanisms are properly closed.
DOCKET (2)
LER NUMBER (6)
PAGE 13)
SEQUENTIAL I REVISION YEAR NUMBER NUMBER 05000289 2003 001 00 2
OF 4
I.
Plant Operating Conditions Before Event:
TMI-1 was operating at 100 percent power II.
Status of Structures, Components, or Systems that were Inoperable at the Start of the Event and that Contributed to the Event:
The Auxiliary Building Supply fan was out of service as a result of maintenance.
Ill.
Event Description
On June 24, 2003, at approximately 0630 hours0.00729 days <br />0.175 hours <br />0.00104 weeks <br />2.39715e-4 months <br /> the NRC resident inspector, while on tour of the 322' elevation of the Control Building, noticed that a 2 square foot duct access panel *[VI/ DUCT PL] for the Control Building Ventilation System supply duct was open. Upon notification, the Control Room dispatched the In-Plant Supervisor to the scene and the access panel was promptly closed and properly secured. This condition was analyzed and determined to be reportable in accordance with 10 CFR 50.72 (b)(3)(ii)(B) and 10 CFR 50.72 (b)(3)(v)(D). The NRC Operations Center was notified on June 25, 2003 at 1945 hours0.0225 days <br />0.54 hours <br />0.00322 weeks <br />7.400725e-4 months <br />.
The open access panel on a ventilation duct within the Control Building Envelope (CBE) provided a leakage path for air that is used to pressurize the CBE. If the ventilation system were operating in the emergency recirculation configuration, this would have unbalanced the ventilation system, which could have lowered the pressure in parts of the CBE below that needed to maintain a positive pressure within the envelope. A positive pressure within the CBE is part of the design basis for Control Room Habitability and is needed to minimize the inleakage of unfiltered air into the CBE.
IV.
Component Failure Data
This event was not the result of a component failure.
V.
Cause of Event
The apparent cause of this event is the spiral cam-type latching mechanisms were not properly closed. The application of this design relies on friction to hold the latching mechanism in the closed position. The further the cam is rotated, the tighter the clamping force.
A review of ventilation flow trends indicated that the duct in the vicinity of the "found opens access panel experienced a negative pressure shortly before the access panel was found open. The negative pressure was due to a planned, non-routine ventilation configuration, i.e. auxiliary building supply fan out of service with two auxiliary building ventilation exhaust fans operating. As a result of this pressure change, it is postulated that the access panel door deflected inward removing some of the force on the latching mechanisms, allowing the latches to become disengaged and the access panel to open.
DOCKET (2 LER NUMBER (6)
PAGE (3) l SEQUENTIAL REVISION YEAR I
NUMBER I NUMBER l 05000289 2003 001 00 3
OF 4
VI.
Automatic or Manually Initiated Safety System Responses:
No safety system responses occurred or were required to occur.
VII.
Assessment of the Safety Consequences and Implications of the Event:
This event produced no adverse safety consequences, since the Control Building Ventilation system was not required to be placed in the emergency recirculation configuration during the time the access panel was open.
The access panel is located in an area that is toured shiftly by a Control Room Operator (CRO) and is readily visible. Therefore, it is reasonable to expect that this open access panel would have been identified by a CRO during the normal operator tours.
The Control Room Habitability design basis assumes that all of the filtered air supply used to pressurize the Control Building emergency envelope comes from the Air Intake Tunnel source, which is approximately 300 feet from the Reactor Building. If, during the period in which this access panel was open, an emergency required that the Control Building Ventilation System be placed in its emergency mode, the system would have been operating outside of its design basis. The open access panel would have allowed additional air flow beyond the design configuration to be removed from the 322' Control Building (within the CBE) and exhausted into the 305' elevation of the Control Building and into the Auxiliary Building (outside the CBE). Because less airflow and pressure would be provided to the rest of the CBE, the CBE ventilation would then have been unbalanced. Some areas of the CBE could not have been assured of having sufficient air pressure to maintain a positive pressure with respect to adjacent areas outside the CBE to prevent unfiltered in-leakage. In the event of a design basis accident (DBA) requiring the control tower ventilation system to be put in the emergency recirculation configuration, the condition could have resulted in increased airborne activity in the control tower ventilation system.
VIII.
Previous Events of a Similar Nature:
There have been no similar events reported at TMI.
IX.
Corrective Actions
Actions Taken:
The open access panel was promptly closed, and the latching mechanisms were verified to be properly closed. The System Engineer walked down 45 accessible access panels within the control building. Two additional panels were found with each panel having one of its two spiral cam-type latches loose. Each panel's remaining latch was tight and the panel doors were being held in the closed position. The loose latches were properly closed.
DOCKET 12)
LER NUMBER (6)
PAGE (3) lI I SEQUENTIAL REVISION H YEAR I
NUMBER NUMBER 05000289 2003 001 00 4
OF 4
Actions Planned:
Surveillance and Maintenance procedures for safety related ventilation systems will be reviewed to identify any access panels in safety related ventilation systems that are periodically opened. The associated, readily accessible latching mechanisms will be inspected and verified properly closed.
This activity will be completed by 09/30/03.
Surveillance and Maintenance procedures for safety related ventilation systems that require access panels in safety related ventilation systems to be periodically opened will be revised. The revision will add steps to verify the latching mechanisms are properly closed. This action will be completed by 03/15/04.
- Energy Industry Identification System (EIIS), System Identification (SI) and Component Function Identification (CFI) Codes are included in brackets, [SI/CFI] where applicable, as required by 10 CFR 50.73 (b)(2)(ii)(F).