05000461/LER-2015-001, Regarding Division 1 and Division 2 Reactor Water Cleanup System High Differential Flow Instruments Become Incapable of Performing Their Safety Function
| ML15098A473 | |
| Person / Time | |
|---|---|
| Site: | Clinton  |
| Issue date: | 04/07/2015 |
| From: | Newcomer M Exelon Generation Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| U-604207 LER 15-001-00 | |
| Download: ML15098A473 (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 |
| 4612015001R00 - NRC Website | |
text
m Exeton Generation.
Clinton Power Station 8401 Power Road Clinton, IL 61727 U-604207 10CFR50.73 April 7, 2015 SRRS 5A.108 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555-0001 Clinton Power Station, Unit 1 Facility Operating License No. NPF-62 NRC Docket No. 50-461
Subject:
Licensee Event Report 2015-001-00 Enclosed is Licensee Event Report (LER) 2015-001-00: Division 1 and Division 2 Reactor Water Cleanup System High Differential Flow Instruments Become Incapable of Performing Their Safety Function. This report is being submitted in accordance with the requirements of 10 CFR 50.73.
There are no regulatory commitments contained in this report.
Should you have any questions concerning this report, please contact Mr. Jeffrey Cunningham, Regulatory Assurance Manager, at (217) 937-2800.
Respectfully, 2~ewe Mirkv M
cornier Site Vice President Clinton Power Station JLP/cas Enclosure: Licensee Event Report 2015-001-00 cc:
Regional Administrator - NRC Region III NRC Senior Resident Inspector - Clinton Power Station Office of Nuclear Facility Safety - Illinois Emergency Management Agency
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 01131t2017 102-2014)
.,21 __*"**'Estimated burden per response to comply with this mandatory collection request: 80 hours9.259259e-4 days <br />0.0222 hours <br />1.322751e-4 weeks <br />3.044e-5 months <br />.
Reported lessons learned are incorporated into the licensing process and fed back to industry.
Send comments regarding burden estimate to the FOIA, Privacy and Information Collections LICENSEE EVENT REPORT (LER)
Branch (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by LIE EVnternet e-mail to Infocollects.Resource@nrc.gov, and to the Desk Officer, Office of Information and (See Page 2 for required number of Regulatory Affairs, NEOB-10202, (3150-0104), Office of Management and Budget, Washington, DC 20503. It a means used to impose an information collection does not display a currently valid OMB control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 3. PAGE Clinton Power Station, Unit 1 05000461 1 OF 3
- 4. TITLE Division 1 and Division 2 Reactor Water Cleanup System High Differential Flow Instruments Become Incapable of Performing Their Safety Function
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED I
IFACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR SEQUENTIAL REV MONTH DAY YEAR NUMBER NO.
05000 FACILITY NAME DOCKET NUMBER 02 06 2015 2015 -
001 00 04 07 2015 05000
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply)
[1 20.2201(b)
[]
20.2203(a)(3)(i)
El 50.73(a)(2)(i)(C)
El 50.73(a)(2)(vii)
E] 20.2201(d)
E] 20.2203(a)(3)(ii)
I]
50.73(a)(2)(ii)(A)
El 50.73(a)(2)(viii)(A) 1E 20.2203(a)(1)
El 20.2203(a)(4)
El 50.73(a)(2)(ii)(B)
El 50.73(a)(2)(viii)(B) 20.2203(a)(2)(i)
El 50.36(c)(1)(i)(A)
El 50.73(a)(2)(iii)
El 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL El_20.2203(a)(2)(ii)
El 50.36(c)(1)(ii)(A)
El 50.73(a)(2)(iv)(A)
El 50.73(a)(2)(x)
El 20.2203(a)(2)(iii)
El 50.36(c)(2)
El 50.73(a)(2)(v)(A)
El 73.71 (a)(4)
El 20.2203(a)(2)(iv)
El 50.46(a)(3)(ii)
El 50.73(a)(2)(v)(B)
El 73.71 (a)(5)
El 20.2203(a)(2)(v)
El 50.73(a)(2)(i)(A)
[
50.73(a)(2)(v)(C)
El OTHER El 20.2203(a)(2)(vi)
El 50.73(a)(2)(i)(B)
El 50.73(a)(2)(v)(D)
Specity in Abstract below or in
______________NRC___FoNRCForm66A
- 12. LICENSEE CONTACT FOR THIS LER LICENSEE CONTACT TELEPHONE NUMBER (include Area Code)
Jeffrey Cunningham, Regulatory Assurance Manager 217-937-2800MANU-REPORTABLE MANU-REPORTABLE SYSTEM COMPONENT FACTURER TO EPIX
CAUSE
SYSTEM COMPONENT EPIX X
RT 1G33F041 F130 N
X RT 1G33F046 A391 N
- 14. SUPPLEMENTAL REPORT EXPECTED
- 15. EXPECTED MONTH DAY YEAR SUBMISSION El YES (If yes, complete 15. EXPECTED SUBMISSION DATE)
O NO DATE ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines)
On 2/6/15 at 2300 CST, the Division 1 Reactor Water Cleanup (RT) system differential flow indicator (1 E31 R614A) was observed to be reading greater than 10 gallons per minute (gpm) different from its sister channel, resulting in it failing its channel check. Operators declared this instrument inoperable in accordance with Clinton Power Station Technical Specification (TS) 3.3.6.1, Primary Containment and Drywell Isolation Instrumentation, requiring placing the channel in trip within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> per Required Action D.1. At 2355, the Division 2 RT differential flow indicator (1 E31 R614B) indicated out of specification, requiring entry into Required Action E.1 for two channels inoperable. With both channels inoperable, the leakage detection system was incapable of performing its containment isolation function for RT differential flow. At 0036 on 2/7/15, a fill and vent of the Division 1 RT leak detection instrumentation was completed, restoring Division 1 to an operable status. At 0225 on 2/7/15, a fill and vent of the Division 2 RT leak detection instrumentation was completed, restoring Division 2 to an operable status. An eight-hour ENS notification (#50794) was made at 0637 CST in accordance with 10CFR50.72(b)(3)(v)(C). This event is also reportable under 1 OCFR50.73(a)(2)(v)(C).
NRC FORM 366 (02-2014)
4RC =
PLANT AND SYSTEM IDENTIFICATION
General Electric -- Boiling Water Reactor, 3473 Megawatts Thermal Rated Core Power Energy Industry Identification System (EIIS) codes are identified in text as [XX].
EVENT IDENTIFICATION
A. Plant Operating Conditions Before the Event
Unit: 1 Event Date: 2/6/2015 Event Time: 2355 Central Time Mode: 1 Mode Name: Power Operation Reactor Power: 98 percent
B. DESCRIPTION OF EVENT
On 2/6/15 at 2300 CST, during an operator surveillance performed every shift, Division 1 Reactor Water Cleanup (RT) system flow indicator [FI] instrument 1 E31R614A read 12.9 gallons per minute (gpm),
which is less than normal and greater than 10 gpm difference from its sister channel resulting in a failed channel check. The operators declared this instrument inoperable in accordance with Clinton Power Station Technical Specification (TS) 3.3.6.1, Primary Containment and Drywell Isolation Instrumentation, which required placing the channel in trip within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> per Required Action D.1.
At 2355, Division 2 RT system flow indicator instrument 1 E31 R614B read 0 gpm, which was a change from its previous reading with no process flow path changes. Based on this reading not being credible, operators declared this instrument inoperable, requiring entry into Required Action E.1 for two channels inoperable. Action E.1 requires restoration of isolation capability within one hour.
At 0036 on 2/7/15, a fill and vent of the Division 1 RT leak detection instrumentation was completed, restoring Division 1 to an operable status. At this time, the operators exited Action E.1.
At 0225, a fill and vent of the Division 2 RT leak detection instrumentation was completed, restoring Division 2 to an operable status. At this time, the operators exited Action D.1 and restored the RT high flow system isolation function to operable status.
During the time that both channels were inoperable, the leakage detection system was incapable of performing its containment isolation function for RT differential flow. This condition required an eight hour Event Notification phone call under 10CFR50.72(b)(3)(v)(C). Event Notification#50794 was made at 0637.
C. CAUSE OF EVENT
RT Isolation Valves [ISV] to the Main Condenser [COND] are leaking by resulting in air voids being allowed to enter into RT system piping causing the differential flow instrumentation to provide false readings. Water is leaking by either valves [V] 1 G33F041 or 1 G33F046.
D.
SAFETY CONSEQUENCES
RT Differential Flow greater than 59 GPM for longer than 45 seconds causes an automatic isolation of the RT System. The isolation function of RT is performed by differential pressure transmitters [PDT]
arranged such that all the inputs and outputs are summed to determine losses from the system. The differential pressure transmitters [PDT] that failed were both on the letdown line flow path to the main condenser, which was isolated by multiple valves. Both instruments were found reading further away from the isolation signal than expected due to the presence of an air pocket in the system. This rendered the automatic leak detection / isolation function of the RT system inoperable and as such operations appropriately entered into the applicable TS Required Actions.
There were no actual consequences as a result of the loss of automatic containment isolation function of the affected RT containment isolation valves. This loss of function lasted for approximately 41 minutes.
During this time the manual isolation function was not affected.
Per CPS 4001.02, Automatic Isolation, a manual Group 4 (Reactor Water Cleanup System) isolation could have still been performed in the event that an automatic isolation was required. At no time during this event was the isolation capability of the system compromised, however the automatic isolation based on differential flow instrumentation was compromised until the fill and vent was completed for the system.
Since the automatic isolation capability was compromised, this event is being reported under 10CFR50.73(a)(2)(v)(C) as a loss of safety function condition.
E. CORRECTIVE ACTIONS
The letdown line was pressurized in accordance with CPS 3303.01, Reactor Water Cleanup (RT) to prevent the development of voids in this line from the suspected leaking valves 1 G33F041 or 1 G33F046.
Work Order packages have been created to repair internal leakage of valves 1 G33F041 or 1 G33F046.
F.
PREVIOUS SIMILAR OCCURRENCES No previous reportable events have occurred as a result of a loss of both divisions of RT differential flow.
G. COMPONENT FAILURE DATA
Component Description: 1 G33F041, RWCU Blowdown Warming Bypass Valve Manufacturer: Fisher Controls Model: WCB TYPE EZ Component Description: 1 G33F046, RWCU Drain Flow to Condensate Valve Manufacturer: Anchor Darling Valve Model: C20036