ML042610055
| ML042610055 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 11/21/2003 |
| From: | Cotton S Entergy Operations |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| FOIA/PA-2004-0277, OCAN110302 | |
| Download: ML042610055 (3) | |
Text
Entergy Operations. Inc.
En te ay 1"B S R.
333 Russellville. AR 72802 Tel E08scol ssoo OCAN1 10302 November 21, 2003 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001
Subject:
Request for Additional Information Regarding the July 10, 2003, Fire Protection Regulatory Conference Arkansas Nuclear One - Units 1 and 2 Docket Nos. 50-313 and 50-368 License Nos. DPR-51 and NPF-6
Dear Sir or Madam:
On July 10, 2003, a Regulatory Conference was held in. the NRC's Region IV office in Arlington, Texas involving Arkansas Nuclear One management and staff and NRC representatives. This conference was held to discuss a finding which was preliminarily determined by the NRC to have a risk significance of greater than green (greater than very low safety significance).
The NRC staff requested additional information following the conference. Entergy provided a response to the staffs request in a letter dated August 11, 2003. Following review of that response, the staff determined that further clarification was needed. The NRC's request for clarification of the additional information provided in the August 11, 2003, letter was sent to Entergy in a letter dated September 19, 2003. Entergy's responses to the latest NRC questions are included in the attachment. Due to the length of some of the responses they have been written to a compact disc which is enclosed. Should you have questions or comments, please contact Mr. Glenn Ashley at (479) 858-617.
There are no new commitments contained In this submittal.
Sincerely, o"-Ak N
Sherrie R. Cotton SRC/rhs Attachment/enclosure Va
Attachment to OCAN 110302 Page 3 of 5 ANO Response The table below is an excerpt of Table 32 from the July 3, 2003, submittal and is included for reference.
I_
amage to iwi rea er TauIl nvestigate A4 bus notes fire ocal imulated fire noted oted fire - as part of 8:42:00 0:04:00 1'Imulation script 68K D1512CV2663 P7A TURB STM ire ire Induced reempted by manual trip 8:44:40 0:00:00 ADMISSION VLV POWER) OPEN
_breaker failure nd EFW auto start 7 stablish (dispatch) Fire Brigade OCR Fire procedure etup team and read 8:46:00 0:03:00 8CV CV2800 EFW P-7B Suction ire Simulated failure rum off P7B to protect 8:49:14 0:08:46
'rom CST) 0
_ump 909 HS2805 STOP, EFW PUMP Coal Represents manual ntroduced Into simulation 8:55:00 0:02:00 T7B.
HS-2805 TRUE control upon local call 10 ocal manual control of EFW 7A ocal B
ack off EFW flow Adjust SPEED CNTR on 8:53:00 0:16:00
'throttle 2620 and 2627) lo prevent overfill EFW PHA, HIC-6601)
I
.8 5 1 Tall for site area emergency MCR in procedures erify location on 9:06:00 0:02:20
.eclaration of Site Area Emergency 12a 1512 - (CV2663 P7A turbine Local New attachment to :ire damage over by this team admission valve power) revent spurious ime PEN from breaker room closure 13 5241 - (CV2667 P7A turbine
-ocal New attachment ire damage over by this team admission valve power) ime
_OPEN from breaker room 14 Manual start of HPI from A3 ocal Restore Injection Use local control 9:04:00 0:22:00 pump operation 15 ao to A3 and be ready to Check ocal rotect A3 safety At location ready for 9:32:00 0:02:00 equipment bus action I
16 Checkpo ition of A-p6 Local rotect A3 safety 9:38:00 0:02:00 W
1 1644vq us
___I__
I This sample timeline is based on the data from Crew 1 which did not have the revised procedure. Therefore, items 12 and 13 are not applicable. The last column provides the time taken to complete the action from the initial cue.
T = 0:00:00 (8:39:39) Control Room indicators indicate a loss of the green train 4160V electrical bus (A4). An auxiliary operator is dispatched to investigate the A4 bus. The operator reaches the scene at T = 0:02:21.
T = 0:00:10 (8:39:49) The loss of A4 causes multiple alarms in the control room. Based on the numerous alarms a manual reactor trip is initiated at T = 0:00:22. Subsequently, all control rods are fully inserted.
Attachment to OCAN 110302 Page 4 of 5 T = 0:01:59 (8:41:38) To prevent additional damage to the A4 switchgear, the green train emergency diesel lock-out is initiated. Operating this switch prevents the green diesel from connecting to the A4 switchgear at T = 0:03:21.
T = 0:02:21 (8:42:00) Auxiliary operator reports fire in the A4 switchgear room. A.Tr
- : c?)
- doA, T = 0:02:22 (8:42:01) The steam driven EFW pump (P7A) automatically starts due to low steam generator level. Control room operator observes the start of the pump and continues to monitor steam generator level for signs of overfill (see T = 0:13:21). Note: The electric driven EFW pump (P7B) also starts on low steam generator level.
T = 0:05:01 (8:44:40) As a result of fire damage, power is lost to CV2663 (steam inlet to P7A). The pre-fire plan notes that CV2663 may require manual operation (if necessary, breaker D1512 would be opened to deenergize the circuit and the handwheel would be utilized to open the valve). Since the low steam generator level caused the EFW system to actuate, CV2663 opens (on EFIC) prior to power being lost to the valve (i.e. at T = 0:02:22).
Thus, no local action is required.
.i uz: v>
3C2 A -
T = 0:06:21 (8:46:00) Fire Brigade is notified of fire and dispatched to the A4 switchgear room.
A?5 T = 0:09:35 (8:49:14) Due to fire damage, the suction valve (CV2800) for P7B spuriously closes.
T = 0:13:21 (8:53:00) Control Room operator observes rising steam generator level. An operator is dispatched to manually throttle the P7A discharge valves (CV2620 and CV2627). The valves are throttled per control room direction to maintain steam generator level at T = 0:29:21. At this point, decay heat is being adequately removed from the reactor via the EFW system.
T = 0:15:21 (8:55:00) Control Room operator recognizes that suction to P7B has been Z
impacted and turns pump off in an attempt to prevent pump damage at 0:17:21.
T = 0:24:21 (9:04:00) Control Room operator notes pressurizer level decrease.
HPI pump (P36A) does not respond to remote control due to loss of control switchgear. An operator is dispatched to start P36A from the A3 switchgear.
auxiliary lube oil pump alignment, RCS injection is initiated at T = 0:46:21.
Red train power to Including T = 0:26:21 (9:06:00) Site area emergency is declared and announced at 0:28:41.
T = 0:52:21 (9:32:00) Operator is dispatched to A3 switchgear to monitor/control operation of P36A. and other A3 breakers.
T = 0:58:21 (9:38:00) Breaker A306 position is verified to ensure that P36A is operating.
At this point, decay heat is being removed by the EFW system (P7A) and RCS level is being maintained by the HPI pump (P36A).