05000483/LER-2015-001, Regarding Completion of a Shutdown Required by the Technical Specifications - TS 3.4.13
| ML15260B362 | |
| Person / Time | |
|---|---|
| Site: | Callaway  |
| Issue date: | 09/17/2015 |
| From: | Cox B Ameren Missouri, Union Electric Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| ULNRC-06243 LER 15-001-00 | |
| Download: ML15260B362 (8) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 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), Loss of Safety Function 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| LER closed by | |
| IR 05000483/2016004 (25 January 2017) | |
| 4832015001R00 - NRC Website | |
text
~~
~Ameren MISSOURI Callaway Plant September 17, 2015 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 ULNRC-06243 10 CFR 50.73(a)(2)(i)(A)
Ladies and Gentlemen:
DOCKET NUMBER 50-483 CALLAWAY PLANT UNIT 1 UNION ELECTRIC CO.
RENEWED FACILITY OPERATING LICENSE NPF-30 LICENSEE EVENT REPORT 2015-001-00 COMPLETION OF A SHUTDOWN REQUIRED BY THE TECHNICAL SPECIFICATIONS The enclosed licensee event report is submitted in accordance with 10CFR50.73(a)(2)(i)(A) to report the completion of a shutdown required by the Technical Specifications.
This letter does not contain new commitments.
Enclosure Sincerely,
~if~
Barry L. Cox Senior Director, Nuclear Operations PO Box 620 Fulton, MO 65251 AmerenMissouri.com STARS
- Alliance
ULNRC-06243 DATE Page2 cc:
Mr. Marc L. Dapas Regional Administrator U.S. Nuclear Regulatory Commission Region IV 1600 East Lamar Boulevard Arlington, TX 76011-4511 Senior Resident Inspector Callaway Resident Office U.S. Nuclear Regulatory Commission 8201 NRC Road Steedman, MO 65077 Mr. L. John Klos Project Manager, Callaway Plant Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Mail Stop 0-8B 1 Washington, DC 20555-2738
ULNRC-06243 DATE Page 3 Index and send hardcopy to QA File A160.0761 Hardcopy:
Certrec Corporation 4150 International Plaza Suite 820 Fort Worth, TX 76109 (Certrec receives ALL attachments as long as they are non-safeguards and may be publicly disclosed.)
Electronic distribution for the following can be made via LER ULNRC Distribution:
F. M. Diya D. W. Neterer L. H. Graessle B.L.Cox T. E. Herrmann S. A. Maglio T. B. Elwood Corporate Oversight Corporate Communications NSRB Secretary Performance Improvement Coordinator Resident Inspectors (NRC)
STARS Regulatory Affairs Mr. John O'Neill (Pillsbury Winthrop Shaw Pittman LLP)
Missouri Public Service Commission
NRC FORM 366 (01-2014)
U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 01/31/2017 LICENSEE EVENT REPORT (LER)
(See reverse for required number of digits/characters for each block)
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 Branch (T-5 F53),
U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by internet e-mail to infocollects.Resource@nrc.gov, and to the Desk Officer, Office of Information and Regulatory Affairs, NEOB-1 0202, (3150-01 04), Office of Management and Budget, Washington, DC 20503. If a means used to impose an information collection does not display a currenUy valid OMB control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 1. FACILITY NAME Callaway Plant Unit 1
- 2. DOCKET NUMBER 05000483
,3. PAGE 1 OF 5
- 4. TITLE Completion of a Shutdown Required by the Technical Specifications - TS 3.4.13
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED FACILITY NAME DOCKET NUMBER YEAR I SEQUENTIAL I REV MONTH NUMBER NO.
MONTH DAY YEAR DAY YEAR FACILITY NAME DOCKET NUMBER 07 23 2015 2015 - 001 -
00 09 17 2015
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR§: (Check all that apply) 0 20.2201(b) 0 20.2203(a)(3)(i) 0 50.73(a)(2)(i)(C) 0 50.73(a)(2)(vii) 0 20.2201 (d) 0 20.2203(a)(3)(ii) 0
- 50. 73(a)(2)(ii)(A) 0
- 50. 73(a)(2)(viii)(A) 0 20.2203(a)(1) 0 20.2203(a)(4) 0 50.73(a)(2)(ii)(B) 0 50.73(a)(2)(viii)(B) 1 0
20.2203(a)(2)(i) 0 50.36(c)(1)(i)(A) 0 50.73(a)(2)(iii) 0 50.73(a)(2)(ix)(A) 1-1-o.-P-O_W_E_R_L_E_V-EL-----10 20.2203(a)(2)(ii) 0 50.36(c)(1)(ii)(A) 0 50.73(a)(2)(iv)(A) 0 50.73(a)(2)(x) 0 20.2203(a)(2)(iii) 0 50.36(c)(2) 0 50.73(a)(2)(v)(A) 0 73.71(a)(4) 0 20.2203(a)(2)(iv) 0 50.46(a)(3)(ii) 0
- 50. 73(a)(2)(v)(B) 0 73.71 (a)(5) 100 0
20.2203(a)(2)(v)
~ 50.73(a)(2)(i)(A) 0 50.73(a)(2)(v)(C) 0 OTHER 0
20.2203(a)(2)(vi) 0 50.73(a)(2)(i)(B) 0 50.73(a)(2)(v)(D)
Specify in Abstract below or in Cooldown of the RCS was initiated at 1210. During the cooldown, the B Main Feedwater Pump was tripped. This led to a manual Auxiliary Feedwater initiation which is discussed in LER 2015-002-00.
At an RCS pressure of approximately 950 psig, a containment entry was made. The leak location was determined to be at the flange downstream of valve BBV0400, CVCS Aux Spray Drain Valve. At this time it was determined that the leakage was unidentified leakage, not RCS pressure boundary leakage. BBV0400 was closed one quarter turn and leakage reduced to approximately 60 drops per minute which is less than the 1 gpm TS limit for unidentified leakage. TS 3.4.13 Conditions B and A were exited at 1 725.
The flange downstream of valve BBV0400 was removed, and its Gore-Tex gasket was removed.
As noted above, the leakage past BBV0400 valve seat was observed to be 60 drops per minute. A Flexitallic gasket was placed in the flange, and the flange was bolted and tightened to approximately 150 ft-lbs. Later, aRCS heat-up was commenced. At normal operating temperature and pressure, no leakage was observed at BBV0400 valve and flange. The reactor and secondary plant startup was continued.
- 4.
ASSESSMENT OF SAFETY CONSEQUENCES
As mentioned above, the BBV0400 drain line connection to the Auxiliary Spray header contains a 3/8" orifice that serves as the designed Safety Class break between the ASME Class 1 and Class 2 portions of the piping. This 3/8" orifice is a design feature that enables the normal makeup system to be capable of providing makeup flow while maintaining pressurizer level by limiting the maximum break flow to less than the available charging flow. Although the leak was determined to exceed the TS limit for unidentified leakage, the leak was well within the capacity of a charging pump, as it was much less than the flow that would result from a postulated break in the Class 2 drain line. Thus, there was no significant safety impact on the plant.
In terms of a Probabilistic Risk Assessment (PRA), the leak was classified as a Very Small LOCA. The associated success criteria included charging and secondary or alternate core cooling with RHR in the injection mode, but it did not require RHR recirculation.
The incremental change in core damage frequency was determined to be less than 1E-6; therefore, this event was of very low risk significance.
Use of the PRA model to evaluate the event provides for a comprehensive, quantitative assessment of the potential safety consequences and implications of the event, including consideration of alternative conditions beyond those analyzed in the FSAR.
- 5.
REPORTING REQUIREMENTS
- 6. LER NUMBER I
SEQUENTIAL I NUMBER 001 REV NO.
00
- 3. PAGE 4
OF 5
This LER is submitted pursuant to 10 CFR 50. 73(a)(2)(i)(A) to report a completion of a shutdown required by the Technical Specifications. The event, i.e., initiation of a shutdown required by the Technical Specifications due to the leak from the piping around valve BBV0400, was reported to the NRC via Event Notification51253 on July 23, 2015.
The manual actuation of the auxiliary feed water system was reported in Callaway Plant LER 2015-002-00.
- 6.
CAUSE OF THE EVENT
The cause of the plant shutdown was an RCS leak in excess of the limit specified in the Technical Specifications. It was determined that the leak was due to seat leakage through the RCS Pressurizer CVCS Auxiliary Spray Supply Drain valve BBV0400 and then through the non-safety related pipe flange immediately downstream of the valve. This leakage ultimately placed the plant in Condition B ofTS 3.4.13, requiring the plant to be in Mode 3 in 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> per Required Action B.1.
The cause of the leakage past the seat of valve BBV0400 will be determined after the upcoming refueling outage.
An update to the cause( s) of the event will be provided via a supplement to the LER.
- 7.
CORRECTIVE ACTIONS
The leakage past the seat of valve BBV0400 was reduced to approximately 60 drops/minute which is below the TS limit for unidentified leakage of 1 gallon per minute. The valve will be repaired or replaced during the upcoming refueling outage.
The gasket in the flange downstream of valve BBV0400 was replaced with a flexitallic gasket.
An update to the corrective actions will be provided via a supplement to the LER.
- 8.
PREVIOUS SIMILAR EVENTS
A review of Callaway LERs for the past three years did not find any in which Callaway reported completion of a shutdown required by the Technical Specifications.
LICENSEE EVENT REPORT (LER)u.s. NUCLEAR REGULATORY coMMISSION CONTINUATION SHEET
- 2. DOCKET 05000483 YEAR 2015
- 6. LER NUMBER REV I
SEQUENTIAL I NUMBER l
NO.
001 00
- 3. PAGE 5
OF 5
In July 2013, Callaway submitted LER 2013-006-00 for RCS leakage from a crack in a socket weld located where a 3/4-inch vent valve is connected to B train injection piping which in tum is connected to a cold leg of the RCS. The estimated leakage rate through the crack was 6 drops per minute.
The plant's corrective action system also documents an event from November 2014 where a sample from a containment radiation monitor showed indication of a possible RCS leak. A socket weld downstream of the CVCS Letdown Orifice B Outlet Throttle Valve developed a leak which required isolation of normal letdown and placing excess letdown in service.