05000455/LER-2010-001, Reactor Protection and Auxiliary Feedwater System Actuation Signals from Low Steam Generator Level Due to Inadequate Surveillance Testing
| ML101720120 | |
| Person / Time | |
|---|---|
| Site: | Byron  |
| Issue date: | 06/18/2010 |
| From: | Enright D Exelon Generation Co, Exelon Nuclear |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| BYRON 2010-0064 LER 10-001-00 | |
| Download: ML101720120 (4) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded 10 CFR 50.73(a)(2)(viii)(A) 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 10 CFR 50.73(a)(2)(viii)(B) 10 CFR 50.73(a)(2)(iii) 10 CFR 50.73(a)(2)(ix)(A) 10 CFR 50.73(a)(2)(iv)(A), System Actuation 10 CFR 50.73(a)(2)(x) 10 CFR 50.73(a)(2)(v)(A), Loss of Safety Function - Shutdown the Reactor 10 CFR 50.73(a)(2)(v)(B), Loss of Safety Function - Remove Residual Heat 10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(iv), System Actuation |
| 4552010001R00 - NRC Website | |
text
Exelon Cener:Jlion Cornpany. LLC Byron Station 4450 No"th Cerman Church Road f3yron, 1[, 61010.. 9794 June 18, 2010 LTR:
BYRON 2010-0064 File:
1.10.0101 Nuclear 10 CFR 50.73 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Byron Station, Unit 2 Facility Operating License No. NPF-66 NRC Docket No. STN 50-455
Subject:
Licensee Event Report 2010-001-00, "Reactor Protection and Auxiliary Feedwater Actuation Signals from Low Steam Generator Level Due to Inadequate Surveillance Testing" The enclosed Licensee Event Report (LER) is being submitted in accordance with 10 CFR 50.73, "Licensee event report system," paragraph (a)(2)(iv), as a manual or automatic actuation of a safety system required to be reported. The LER involves the April 19,2010, event involving the inadvertent generation of a Reactor Protection trip initiation and Auxiliary Feedwater initiation signal during shutdown surveillance testing.
There are no regulatory commitments contained in this letter. Should you have any questions concerning this submittal, please contact Mr. David Gudger, Regulatory Assurance Manager, at (815) 406-2800.
RespectfuIIy,
~~~~
Daniel J. Enright Site Vice President Byron Station
Enclosure:
LER Number 455-2010-001-00
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150*0104 EXPIRES: 08/31/2010 (9-2007)
, the NRC may digits/characters for each block) not conduct or sponsor, and a person is not reqUired to respond to, the information collection.
- 13. PAGE Byron Station, Unit 2 05000455 1 of 3
- 4. TITLE Reactor Protection and Auxiliary Feedwater System Actuation Signals from Low Steam Generator Level Due to Inadequate Surveillance Testing
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED YEAR ISEQUENTIALIREV FACILITY NAME DOCKET NUMBER MONTH DAY YEAR NUMBER NO.
MONTH DAY YEAR N/A FACILITY NAME DOCKET NUMBER 4
19 2010 2010 001 00 06 18 2010
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply) 4 o 20.2201(b) o 20.2203(a)(3)(i) o 50.73(a)(2)(i)(C) o 50.73(a)(2)(vii) o 20.2201(d) o 20.2203(a)(3)(ii) o 50.73(a)(2)(ii)(A) o 50.73(a)(2)(viii)(A) o 20.2203(a)(1) o 20.2203(a)(4) o 50.73(a)(2)(ii)(B) o 50.73(a)(2)(viii)(B) o 20.2203(a)(2)(i) o 50.36(c)(1 )(i)(A) o 50.73(a)(2)(iii) o 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL o 20.2203(a)(2)(ii) o 50.36(c)(1 )(ii)(A)
I:8J 50.73(a)(2)(iv)(A) o 50.73(a)(2)(x) o 20.2203(a)(2)(iii) o 50.36(c)(2) o 50.73(a)(2)(v)(A) o 73.71 (a)(4) 000 o 20.2203(a)(2)(iv) o 50.46(a)(3)(ii) o 50.73(a)(2)(v)(B) o 73.71(a)(5) o 20.2203(a)(2)(v) o 50.73(a)(2)(i)(A) o 50.73(a)(2)(v)(C) o OTHER o 20.2203(a)(2)(vi) o 50.73(a)(2)(i)(B) o 50.73(a)(2)(v)(D)
Specify in Abstraci below or in 2010 001 00 At 0503, during the restoration section of the FWIV stroke procedure, a low level actuation condition on the 20 SG inadvertently occurred, which resulted in the generation of a RP trip initiation, AF initiation, and SO isolation signals.
Though the actuation logic was satisfied and valid actuation signals generated, it did not result in the actuation of any plant components in the systems required to be reported in accordance with 10 CFR 50.73(a)(2)(iv). The Unit 2 reactor trip breakers were already open and both AF pumps were removed from service. The SO isolation occurred as expected.
SG levels were restored, initiation signals reset, and the cooldown to Mode 5 continued. This event is being reported to the NRC in accordance with 10 CFR 50.73(a)(2)(iv).
C.
Cause of the Event
An investigation into this event identified the following causes:
The Operations supervisory oversight by the test coordinator and U2 Supervisor of the FWIV testing activity was less that adequate.
The FWIV surveillance procedure was inadequate in that it did not provide steps to mitigate a decreasing SG level such that the low level actuation setpoint would not be challenged.
The procedure was executed at a higher reactor coolant temperature than typical in previous outages. This allowed for a higher SG level reduction rate.
Not conducting an additional pre-job brief for the test when an operator was selected as part of the test team that did not receive the refresher training.
O.
Safety Significance
There were no adverse safety consequences from this event. The RP and AF initiation protection functions from a low level SG are not required for this mode of operation. The control rods were already fully inserted, the reactor trip breakers open and the AF pumps were removed from service.
E.
Corrective Actions
The roles and responsibilities of key outage operations positions will be reinforced with appropriate Operations personnel.
The FWIV stroke procedure will be revised to incorporate steps to allow for SG level recovery strategies before an actuation setpoint is reached.
A FWIV stroke procedure prerequisite will be revised to require both trains of RH to be placed in shutdown cooling.
The crediting of a pre-job brief for refresher training for an actual activity will be revisited_
F.
Previous Occurrences
No previous events involving safety system actuation signals inadvertently generated due to similar causes were identified at Byron Station in the previous three years.
NRC FORM 36M (9-2007)
PRINTED ON RECYCLED PAPER