05000366/LER-2013-001, Regarding Unplanned RPS Actuation Due to Scram Discharge Volume High Level During Surveillance Test
| ML13102A240 | |
| Person / Time | |
|---|---|
| Site: | Hatch  |
| Issue date: | 04/12/2013 |
| From: | Pierce C Southern Nuclear Operating Co |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| NL-13-0648 LER 13-001-00 | |
| Download: ML13102A240 (6) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2) 10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded 10 CFR 50.73(a)(2)(ii)(8) 10 CFR 50.73(a)(2)(iii) 10 CFR 50.73(a)(2)(ix)(A) 10 CFR 50.73(a)(2)(x) 10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(i)(8) 10 CFR 50.73(a)(2)(iv)(A), System Actuation |
| 3662013001R00 - NRC Website | |
text
Charles R. Pierce Southern Nuclear Regulatory Affairs Di rector Operating Company, Inc.
40 Inverness Center Parkway Post Office Box 1295 Birmingham, Alabama 35201 Tel 205.992.7872 Fax 205.992.7601 SOUTHERN '\\
COMPANY April 12, 2013 Docket Nos.: 50-366 NL-13-0648 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555-0001 Edwin I. Hatch Nuclear Plant Licensee Event Report 2013-01 Unplanned RPS Actuation due to Scram Discharge Water Level during Surveillance Testing Ladies and Gentlemen:
In accordance with the requirements of 1 OCFR50. 73(a)(2)(iv)(A), Southern Nuclear Operating Company hereby submits the enclosed Licensee Event Report concerning an unplanned RPS actuation that occurred during the course of performing refueling interlocks surveillance testing.
This letter contains no NRC commitments. If you have any questions, please contact Doug McKinney at (205) 992-5982.
Respectfully submitted, C. R. Pierce Regulatory Affairs Director CRP/sbtlmd Enclosure: LER 2-2013-001
U. S. Nuclear Regulatory Commission NL-13-0648 Page 2 cc: Southern l\\Juclear Operating Company Mr. S. E. Kuczynski, Chairman, President & CEO Mr. D. G. Bost, Executive Vice President & Chief l\\Juclear Officer Mr. D. R. lVIadison, Vice President - Hatch Mr. B. L. Ivey, Vice President - Regulatory Affairs Mr. B. J. Adams, Vice President - Fleet Operations Mr. M. A. Dowd - OE Coordinator RTYPE: CHA02.004 U. S. Nuclear Regulatory Commission Mr. V. M. McCree, Regional Administrator Mr. R. E. Martin, NRR Senior Project Manager - Hatch Mr. E. D. Morris, Senior Resident Inspector - Hatch
Enclosure NL-1,"-U'U"TU Licensee 3-001 Unplanned RPS Actuation due to High Level during
RC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 1013112013 10*2010)
LICENSEE EVENT REPORT (LER)
Edwin I. Hatch Nuclear Plant DAY YEAR 05000 04 05000
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR§: (Check a/I that apply) o 20.2201 (b) 0 20.2203(a)(3)(i) 50.73(a)(2)(i)(C) 50.73(a)(2)(lIii) 5 o 20.2201(d) 20.2203(a)(1) 0 0
20.2203(a)(3)(ii) 0 0
50.73(a)(2)(ii)(A) 50.73(a)(2)(ii)(8) 50.73(a)(2)(lIiii)(A) 50.73(a)(2)(lIiii)(8) 20.2203(a)(2)(i) 50.36(c)(1)(i)(A) 50.73(a)(2)(iii) 50.73(a)(2)(ix)(A)
O. POWER LEVEL o 20.2203(a)(2)(ii) 20.2203(a)(2)(iii) 0 50.36(c)(1 )(ii)(A) 50.36(c)(2) 0 50.73(a)(2)(ill)(A)
- 50. 73(a)(2)(II)(A) 50.73(a)(2)(x) o 73.71(a)(4) 000 20.2203(a)(2)(i1l) o 20.2203(a)(2)(1I) 50.46(a)(3)(ii) 50.73(a)(2)(i)(A) 50.73(a)(2)(1I)(B) 50.73(a)(2)(II)(C) 73.71 (a)(5)
OTHER o 20.2203(a)(2)(lIi) 50.73(a)(2)(i)(8) 0 50.73(a)(2)(II)(D)
Specify in Abstract below or in NRC Form 36M
- 12. LICENSEE CONTACT FOR THIS LER MANU ICAU:SE ISY~E:MICOMI'ONE:NTI~
COMPONENT FACTURER
- 14. SUPPLEMENTAL REPORT EXPECTED ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines)
On 2116/2013, at approximately 0310 eastern standard time (EST), Unit 2 was in the refueling mode, when a valid unplanned reactor protection system (RPS) actuation occurred as a result of scram discharge volume (SDV) level. Following shutdown for refueling the scram vent and drain valves would not open as which resulted in water remaining in the SDV. The refueling interlocks surveillance testing was being performed in accordance with the Operations surveillance procedure with the SDV water level above the setpoints for the "rod withdrawal block" and the "scram trip" in conjunction with closed SDV vent and drain valves. Jumpers had been installed to the rod block signal, and the scram signal had been the "Disch Vol Hi Level Byp" switch.
When the Reactor Mode Switch was in the "Start & Hot Standby" position, a full reactor protection system (RPS) actuation occurred. Subsequent investigation revealed that the SDV high level bypass is only active with the mode switch in the "Shutdown" or "Refuel" positions.
The RPS actuation was caused by the presence of a water level in the SDV above the trip setpoint and by a less than adequate procedure. The absence of procedure prerequisites to confirm the SDV Hi Level Rod Block and trip Signals were not present prior to performing the refueling interlocks surveillance procedure resulted in positioning the reactor mode switch to the "STARTUP" position with the SDV trip signal This caused the SDV high level trip to no longer be bypassed resulting in the RPS actuation. The SDV high level condition was cleared and beginning of shift training (BaST) was issued to inform licensed operators of the event. Actions to prevent recurrence involved revision of Units 1 and 2 refuelin interlocks surveillance rocedures.
NRC FOAM 366 (!HOO7)
PAINTED ON RECYCLED PAPER Electric - Boiling Water Reactor Industry Identification System appear in text as (EllS XX).
DESCRIPTION OF EVENT
On 2/16/13, Unit 2 was in a outage and Refueling Functional was being in accordance with the Operations surveillance procedure as a prerequisite Fuel Movement At the performance the refueling interlocks surveillance scram discharge volume (SDV) was above trip setpoints for the Rod Withdrawal Block and SDV as a result of SDV vent and drain valves being Instrument and Control (I&C) technicians installed jumpers to bypass rod block the SDV scram signal had bypassed the SDV bypass switch that was designed to accomplish this when the reactor is shutdown. During the course of the refueling interlocks surveillance testing a procedure step required the Reactor Mode to be in the "START &
STBY" A valid actuation was received when the Reactor Mode Switch was taken to the
& HOT position.
During a investigation, a review of the logic associated with the SDV high condition was performed.
personnel confirmed that the high level is only active when the mode is in the "SHUTDOWN" or "REFUEL" position.
Operations personnel would to be of this information in the where movement of the mode to a required will cause a trip signal on high level if is present. A review of other Operations and Maintenance procedures that involve movement of reactor mode switch indicated that is a provIsion in "Prerequisites" section of procedures to confirm that the SDV high level rod out block and scram are clear.
refueling interlocks functional testing surveillance procedure did not contain this The unplanned actuation was trip setpoint procedure to confirm trip signals were not present prior to performing the interlocks surveillance procedure in the reactor mode switch to the P" position with the SDV trip signal present.
"tAl""v,,'U the high level trip to no longer bypassed resulting in RPS actuation. Contributing to the event was the fact that the Operations shift that the SDV Hi Bypass was only active when Reactor SHUTDOWN or SDV high level condition which is a valid Even though
'SCRAM' function had control being fully the associated logic had not been removed from For this reason this is a valid actuation and is reported in accordance with 10 50.73(a) (2) (iv) (A). LICENSEE EVENT REPORT (LER) u.s. NUCLEAR REGULATORY COMMISSION (10*2010)
CONTINUATION SHEET
- 1. FACILITY NAME
- 2. DOCKET
- 6. LER NUMBER
- 3. PAGE SEQUENTIAL IREVISION NUMBER J NUMBER Edwin I. Hatch Nuclear Plant 05000-366 YEAR I
3 OF 3
2013 01 0
The SDV receives the water displaced by the motion of the CRD pistons during a reactor scram. Should this volume fill to a point where there is insufficient volume to accept the displaced water, control rod insertion would be hindered. Therefore, a reactor scram is initiated while the remaining free volume is still sufficient to accommodate the water from a full core scram. The two types of Scram Discharge Volume Water Level - High Functions are an input to the RPS logic. No credit is taken for a scram initiated from these Functions for any of the design basis accidents or transients analyzed in the FSAR. However, they are retained to ensure the RPS remains OPERABLE.
During this event, the reactor was in the Refueling Mode with the safety function having already been completed with all control rods already fully inserted. The occurrence of this event from "at power" conditions has been analyzed. Based on this information this reported condition has low nuclear safety significance.
CORRECTIVE ACTIONS
The SDV high level condition was cleared to allow performance of the required surveillance procedure for refueling interlocks. A BOST was issued to the Operations Department to inform personnel of the event and to explain the operation of the SDV high level bypass logic as well as other scram bypasses. This BOST explained when each scram bypass is in effect depending on plant mode, plant conditions and reactor mode switch positions.
Corrective actions to preclude recurrence involved procedure revisions for the refueling interlocks surveillance procedures on Unit 1 and Unit 2 to ensure the SDV high level is cleared prior to performance of the affected procedures.
ADDITIONAL INFORMATION
Other Systems Affected:
None
Failed Components Information
None Commitment Information: This report does not create any new permanent licensing
commitments
Previous Similar Events
A review of Hatch LERs was performed from January 2006 to the present and no similar events were identified.