05000440/LER-2009-001, For Perry Nuclear Power Plant, Regarding MSR High Level Signal Causes Turbine Trip and Reactor Protection System Actuation
| ML092380147 | |
| Person / Time | |
|---|---|
| Site: | Perry  |
| Issue date: | 08/20/2009 |
| From: | Bezilla M FirstEnergy Nuclear Operating Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| L-09-211 LER 09-001-00 | |
| Download: ML092380147 (6) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(iv)(A), System Actuation 10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(ii) 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)(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 |
| 4402009001R00 - NRC Website | |
text
FENOC FirstEnergy Nuclear Operating Company Perry Nuclear Power Station 10 Center Road Perry, Ohio 44081 Mark B. Bezilla Vice President 440-280-5382 Fax: 440-280-8029 August 20, 2009 L-09-211 10 CFR 50.73(a)(2)(iv)(A)
ATTN: Document Control Desk U. S. Nuclear Regulatory Commission Washington, DC 20555-0001
SUBJECT:
Perry Nuclear Power Plant Docket No. 50-440, License No. NPF-58 Licensee Event Report Submittal Enclosed is Licensee Event Report (LER) 2009-001, "MSR High Level Signal Causes Turbine Trip and Reactor Protection System Actuation." There are no regulatory commitments contained in this submittal.
If there are any questions or if additional information is required, please contact Mr. Robert Coad, Manager - Regulatory Compliance, at (440) 280-5328.
Enclosure:
LER 2009-001 cc:
NRC Project Manager NRC Resident Inspector NRC Region IIl
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NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB NO. 3150-0104 EXPIRES 8/31/2010 (9-2007)
, the NRC may (See reverse for required number of not conduct or sponsor, and a person is not required to respond to, the digits/characters for each block) information collection.
- 13. PAGE Perry Nuclear Power Plant, Unit 1 05000440 1 OF 5
- 4. TITLE MSR High Level Signal Causes Turbine Trip and Reactor Protection System Actuation
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED STEQUENTIA REV FACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR NUMBER NO.
MONTH DAY YEAR 06 21 2009 2009-001
- - 00 08 20 20091FACILITYNAME DOCKET NUMBER
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply)
El 20.2201(b)
El 20.2203(a)(3)(i)
[I 50.73(a)(2)(i)(C)
E] 50.73(a)(2)(vii)
E] 20.2201(d)
E] 20.2203(a)(3)(ii)
LI 50.73(a)(2)(ii)(a)
F] 50.73(a)(2)(viii)(A)
E] 20.2203(a)(1)
[] 20.2203(a)(4)
[
50.73(a)(2)(ii)(B)
El 50.73(a)(2)(viii)(B)
_ _ 20.2203(a)(2)(i)
E] 50.36(c)(1)(i)(A)
[
50.73(a)(2)(iii)
El 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL LI 20.2203(a)(2)(ii)
Ej 50.36(c)(1)(ii)(A)
Z 50.73(a)(2)(iv)(A)
El 50.73(a)(2)(x)
E] 20.2203(a)(2)(iii)
E] 50.36(c)(2)
[] 50.73(a)(2)(v)(A)
LI 73.71 (a)(4) 100 E] 20.2203(a)(2)(iv)
[] 50.46(a)(3)(ii)
E] 50.73(a)(2)(v)(B)
L] 73.71(a)(5)
LI 20.2203(a)(2)(v)
E] 50.73(a)(2)(i)(A)
LI 50.73(a)(2)(v)(C)
El OTHER Specify in Abstract below
__ 20.2203(a)(2)(vi)
E] 50.73(a)(2)(i)(B)
Ej 50.73(a)(2)(v)(D) or in The root cause for not adjusting the MSR 1 B level instrument micro-switches was that industry operating experience (OE) (0E19872) for improper linkage adjustment of MSR level switches was not evaluated for applicability to Perry. As a result, potential key learnings were not incorporated into plant procedures. In this case, key manufacturer's instruction manual recommendations were not included in the instrument calibration instruction or the 1 R1 2 preventive maintenance work order for performing MSR level switch calibration checks.
The following causes contributed to the event:
" The step sequence specified in the work order performing the switch calibration checks was not followed. No As-Found calibration of the Magnetrol level switches was performed; the Instrumentation and Control (I&C) technicians proceeded to replace the micro-switches. If the intended sequence had been followed, the I&C technicians would have referred to the vendor manual that describes the set-up and adjustment of the micro-switches when replaced. The technicians did not obtain documented permission to skip the As-Found calibration. This skipped step in the process prevented early identification of improper switch adjustments. The manufacturer's instruction manual was not referenced when the micro-switches were replaced.
Issues associated with maintenance of MSR level switches were not enritered in the corrective action process (CAP). These issues included unacceptable micro-switch as-found conditions and micro-switch replacements. As a result, past maintenance experience was not available for trending or use in 1R12 work planning.
Non-safety plant equipment was not considered as significant by the workers.
EVENT ANALYSIS
The moisture separator reheaters (MSRs) are large cylindrical pressure vessels designed to improve the quality and increase the internal energy of the high pressure turbine exhaust steam.
The MSRs increase steam efficiency through the low pressure turbine. Water level in the MSR tanks is controlled to prevent moisture carryover which could damage the turbine. Water in the MSRs is routed to individual drain tanks.
Perry has four MSR tanks identified as 1A, 1 B, 2A, and 2B. Each MSR tank has three Magnetrol Model 402 level switches installed on exterior instrument level trees to provide a turbine trip signal on MSR high water level. Each level switch has two (upper and lower) M-1 type mirco-switches.
Initial troubleshooting subsequent to the scram determined that the upper micro-switch contacts on the three MSR 1 B Magnetrol level switch mechanisms were closed, making up the main turbine trip logic from MSR 1 B. The lower contacts were found open as expected for normal MSR water level.
Prior to the scram, MSR drain tank level control was in normal band and steady. No MSR 1 B level alarms were received to indicate a high MSR water level. The first indication of a problem was the main turbine trip. A review of other level indications associated with MSR 1 B did not indicate a high water level condition or any changes in MSR 1B Drain Tank level control parameters. The MSR 1B drain tank parameters were consistent with the 1A, 2A and 2B drain tank parameters.
The reactor scram was uncomplicated in that all control rods fully inserted, reactor coolant pressure and level were maintained within expected parameters, and no emergency systems actuated in response. The RPS functioned as designed.
The scram event, including plant response, is bounded by the Turbine Trip transient evaluated in the Updated Safety Analysis Report (USAR) Chapter 15, Accident Analysis, section 15.2.3. No plant parameters due to the scram challenged the transients described in the USAR. This transient is categorized as an incident of moderate frequency.
A probabilistic risk assessment (PRA) was performed for the scram event. The PRA calculated a change in core damage frequency (delta CDF) in this case to be 1.7E-07. Since Perry's Large Early Release Frequency (LERF) is an order magnitude less than the core damage frequency, the corresponding change in LERF will be on the order of 1.OE-08. Plant configurations with changes in CDF of less than 1.OE-06 and LERF of less than 1.OE-07 are not considered to be significant risk events.
Based on the above information, this event is considered to be of low safety significance.
CORRECTIVE ACTIONS
The upper micro-switch mounting assemblies and linkages for the three Magnetrol level switch assemblies on MSR 1 B were adjusted to ensure the micro-switch contacts were opening and closing properly and that the switch travel was optimized. The switches were then calibrated satisfactorily. The Magnetrol level switch assemblies on MSRs 1A, 2A, 2B were checked for proper alignment and calibration. Micro-switch trip and reset verifications were performed to confirm proper operation prior to startup; adjustments to the switches were made as necessary. A monitoring plan to check the MSR high level turbine trip contacts during the current operating cycle was established.
The preventative maintenance (PM) tasks and component templates for MSR 1A/B and 2A/B level instruments will be revised to include applicable good practices (such as verifying the "As-Left" contact positions are open) determined from the troubleshooting and maintenance work orders implemented in response to this event. The PM tasks will include the applicable good practices from the monitoring plan orders performed to check the integrity of the MSR logic switch positions.
Instruction ICI-B1-0, Generic Level Instrumentation Calibration (81-0), will be revised to include manufacturer's instructions for micro-switch replacement and adjustment. The calibration section of the Magnetrol vendor manual will be revised to include the level switch adjustment information from the level switch replacement section.
A lessons learned document will be created, for training purposes, that aligns the weaknesses identified in the evaluation of industry OE for improper level switch adjustments and controller settings.
The following lessons learned from this event will be reviewed with I&C personnel:
Refer to technical manuals and submit procedure change requests as necessary to ensure
calibration instructions contain the necessary information.
Importance of collecting "As-Found" data.
Importance of generating condition reports to capture failed components requiring replacement to provide a data stream for trending.
" Procedure use and adherence for performing order operations out of sequence and the possibility of skipping a step.
Work orders were created to perform calibration checks or functional checks on similar applications in the plant of Magnetrol level switches having the M-1 type micro-switch assemblies.
PREVIOUS SIMILAR EVENTS
A review of LERs and the corrective action program database for the past three years did not identify any previous similar events or condition reports relevant to MSR failure mechanisms which defined this event. Corrective actions for the following RPS actuations were reviewed. They would not reasonably be expected to have prevented the MSR scram.
LER 2007-004, Automatic RPS Actuation Due to Feedwater Control Power, Supply failure LER 2007-001, Automatic RPS Actuation Due Reactor Coolant Level Decrease LER 2006-005, Decreasing Instrument Air Pressure Results in Manual RPS Actuation
COMMITMENTS
There are no regulatory commitments contained in this report. Actions described in this document represent intended or planned actions, are described for the NRC's information, and are not regulatory commitments.PRINTED ON RECYCLED PAPERPRINTED ON RECYCLED PAPER