05000483/LER-2003-007, Engineering Evaluations Incorrectly Approved Leaving Health Physics Access Doors Open
| ML032600920 | |
| Person / Time | |
|---|---|
| Site: | Callaway  (NPF-030) |
| Issue date: | 09/11/2003 |
| From: | Witt W AmerenUE |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| ULNRC04900 LER 03-007-00 | |
| Download: ML032600920 (7) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability |
| 4832003007R00 - NRC Website | |
text
AmereniE Callaway Plant PO Box 620 Fulton, MO 65251 September 11, 2003 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Mail Stop P1-137 Washington, DC 20555-0001 ULNRC04900 UE Ladies and Gentlemen:
DOCKET NUMBER 50483 Callaway PLANT UNIT 1 UNION ELECTRIC CO.
FACILITY OPERATING LICENSE NPF-30 LICENSEE EVENT REPORT 2003-007-00 Engineering Evaluations incorrectly approved leaving Health Physics area access doors open.
The enclosed licensee event report is submitted in accordance with 1 OCFR50.73(a)(2)(i)(B), 1 OCFR50.73(a)(2)(ii)(B), 10CFR50.73(a)(2)(v)(D), and 10CFR50.73(a)(2)(vii) to report an event in which engineering evaluations incorrectly approved leaving access doors to the Health Physics area open.
Very truly yours, Warren A. Witt Manager, Callaway Plant WAW/ewh Enclosure j & -" )-'o --W a subsidiary of Ameren Corporation
ULNRC04900 September 11, 2003 Page 2 cc:
Mr. Thomas P. Gwynn Acting Regional Administrator U.S. Nuclear Regulatory Commission Region IV 611 Ryan Plaza Drive, Suite 400 Arlington, TX 76011-4005 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 Records Center Institute of Nuclear Power Operations 700 Galleria Parkway Atlanta, GA 30339
Abstract
On 7/17/03, with Callaway Plant at 100 percent power, an error was found in Engineering Evaluations that approved having the Health Physics (HP) Access doors 32201 and Hot Lab door 32282 open. These doors are pressure boundary doors between the Control Building and Communication Corridor and are required to be closed during accident conditions. With the doors open, HP Access Control fan coil unit SGKO3 would cause air from outside the Control Building to enter the HP Access area and mix with Control Building atmosphere. The Control Building atmosphere is credited in post-accident Control Room radiological consequence analysis and an outside air source has potential for impacting dose received by Control Room staff. An evaluation determined 25 minutes to close these doors in an emergency, which could result in an exposure of approximately 31.5 REM to Control Room staff. This dose was above regulatory limits and the event was classified as reportable as an unanalyzed event and a violation of Technical Specifications. When the door issue was identified, the doors were closed and a plant bulletin was issued indicating the doors were to remain closed except during normal use. Although the Regulatory Guide 1.195 dose limit and ICRP 30 Dose Conversion Factors are not currently part of Callaway's Licensing bases, they do demonstrate the limited safety implications of this event.
NRC FORM 366 (fW)
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I.
DESCRIPTION OF THE REPORTABLE EVENT
A. REPORTABLE EVENT CLASSIFICATION This event is being reported under multiple criteria. It is being reported under:
IOCFR50.73(aX2)(iXB), a condition prohibited by Technical Specifications 10CFR50.73(aX2Xii)(B), an unanalyzed condition 10CFR50.73(aX2)(v)(D), an event or condition that could have prevented fulfillment of a safety function to mitigate the consequences of an accident IOCFRS0.73(aX2)(vil), common-cause Inoperability where a single condition caused two independent trains to become inoperable in a single system designed to mitigate the consequences of an accident.
B. PLANT OPERATING CONDITIONS PRIOR TO THE EVENT Callaway Plant was in Mode 1 at 100 percent power.
C. STATUS OF STRUCTURES, SYSTEMS OR COMPONENTS THAT WERE INOPERABLE AT THE START OF THE EVENT AND THAT CONTRIBUTED TO THE EVENT Not applicable for this event.
D. NARRATIVE SUMMARY OF THE EVENT, INCLUDING DATES AND APPROXIMATE TIMES On July 17, 2003 with Callaway Plant operating at 100 percent power, an error was discovered in Request For Resolutions (RFR) 14826 and 16672 that had approved leaving the Health Physics (HP) Access entrance doors 32201 and Hot Lab Door 32282 open.
These doors are pressure boundary doors between the Control Building and the Communication Corridor and are required to be closed during a Control Room Ventilation Isolation. Following a Control Room Ventilation Isolation, the HP Access Control fan coil unit SGKO3 would cause air in the HP Access Control area to commingle with portions of the Control Building that are credited in the Control Room radiological consequences analysis of record.
With the doors open, air from the HP Access Control area must be considered to be outside air in the radiological consequences analysis.
The entrance to HP Access is a high traffic area and the entrance doors are a set of large missile doors that serve as a fire and pressure boundary. Revision A of RFR 14826 was performed in 1994 and approved leaving the HP Access area doors open to reduce repeat door maintenance and the chance for personnel injury from these heavy doors.
Radiological Engineering and the HVAC System Engineer had performed a review and concluded that leaving the doors to BP Access open would not affect the Licensing Bases analysis. These reviews did not identify that SGKO3 continues to operate after a Control Room Ventilation Isolation Signal (CRVIS) and that operation of SGKO3 following a CRVIS would cause air from the HP Access Control area to commingle with portions of the Control Building credited in the Licensing Bases radiological consequences analysis of record for the Control Room. It was identified that having these doors open would impact the Fire Protection plan and required a Fire Barrier Integrity Record to be generated. This record documented the requirement for a continuous fire watch with these doors propped open. One additional action required by RFR 14826, was to establish controls that required the HP Access doors to be closed upon declaration of a plant emergency. At that time, Key Issue was located within the HP Access area and the requirements to close the HP Access doors and act as fire watch, were assigned to the Security individuals manning Key Issue. Unfortunately, during the RFR review process neither engineering group identified the disallowed air flow path associated with SGKO3.
NRC FORM 36tA (1-2001)
(if more space Is required, use additonal copies of (if more space Is requlr, use addie copes of NRC Fom 366A) (17) the GDC 19 regulatory thyroid dose limit of 30 REM.
Due to exceeding the thyroid dose limit stipulated in T/S 3.7.10 Bases, this event rendered the CRVES inoperable and constituted a violation of T/S 3.7.10. NUREG 1022 only requires an evaluation period of 3 years, thus this event represents a violation of T/S 3.7.10 for the 3 year period from 7/17/00 until 7/17/03 when the problem was identified and rectified.
C. SAFETY CONSEQUENCES AND IMPLICATIONS OF THE EVENT.
As was previously discussed, an evaluation was performed to quantify the impact of the open doors on post-accident radiological consequences. The results indicated that the open doors would result in a more than minimal increase in accident consequences as described in Callaway's FSAR. Additionally, the regulatory limit of GDC 19 would be exceeded. This evaluation was performed using the radiological consequence analysis methodology currently described in Callaway's FSAR.
Additional evaluations were performed using ICRP 30 Dose Conversion Factors (DCF). This evaluation concluded that post-accident consequences would be 22.2 Rem to the thyroid. This value would be bounded by the FSAR reported value and the GDC 19 regulatory limit. Additionally, it was noted that Regulatory Guide 1.195 would allow licensees, with prior NRC approval to use a thyroid dose limit of 50 Rem. Callaway has submitted a License Amendment Request to obtain NRC approval for the use of ICRP 30 DCFs.
Although the Regulatory Guide 1.195 dose limit and ICRP 30 DCFs are not currently part of Callaway's Licensing bases, they do demonstrate the limited safety implications of this event.
HII.
CAUSE OF THE EVENT
The cause was an error in an assumption in Engineering Evaluations which concluded that leaving the doors open would not affect the Licensing Bases analyses.
IV.
CORRECTIVE ACTIONS
Corrective actions were to close the doors, plus issue a plant bulletin to maintain the doors closed. Signs were added to the doors indicating the requirement to maintain the doors closed. Specific instructions were provided to Health Physics personnel to maintain the doors closed. Additionally, Security officers have been informed that these doors are to remain closed at all times, and they will check these doors while on patrol.
The Licensing Impact Review (LIR) form used by engineering personnel to screen proposed plant changes has been revised since RFRs 14826 and 16672 were dispositioned. A new section of questions regarding Control Room Habitability has been added to the LIR form.
V.
PREVIOUS SIMILAR EVENTS
A review of Callaway LER's from 2000 until present did not reveal any similar events.
A review of the Callaway Action Request System (CARS) was performed covering the last three years. Using key word "HP Access doors" and 'blocked doors" text searches, no CARs were identified that revealed potential breaches of the Control Building pressure boundary, and thus potential violations similar to the issue addressed in this LER.
(ff more spew Is required, use adnal copes of NRC Form 366A) (17)
VI.
ADDITIONAL INFORMATION
The system and component codes listed below are from the IEEE Standard 805-1984 and IEEE Standard 803A-1984 respectively.
System:
Not applicable for this event.
Component:
DR