05000293/LER-2015-007, Regarding Single Main Steam Isolation Valve Closure Resulting in Automatic Reactor Scram
| ML15307A006 | |
| Person / Time | |
|---|---|
| Site: | Pilgrim |
| Issue date: | 10/20/2015 |
| From: | Noyes D Entergy Nuclear Operations |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 2.15.070 LER 15-007-00 | |
| Download: ML15307A006 (7) | |
| 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)(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)(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)(B), System Actuation |
| 2932015007R00 - NRC Website | |
text
SEn tergy EDeriy ENuclear ODerectionr c 60Reuaocky Hilleroradc mrvmn David E. Nayes, Director Regulatory & Performance Improvement October 20, 2015 U.S. Nuclear Regulatory Commission.
Attn: Document Control Desk Washington, DC 20555
SUBJECT:
Licensee Event Report 201 5-007-00, Single Main Steam Isolation Valve Closure Resulting in Automatic Reactor Scram Entergy Nuclear Operations, Inc.
Pilgrim Nuclear Power Station Docket No.: 50-293 License No.: DPR-35 LETTER NUMBER:
2.15.070
Dear Sir or Madam:
The enclosed Licensee Event Report (LER) 2015-007-00, Single Main Steam Isolation Valve Closure Resulting in Automatic Reactor Scram, is submitted in accordance with 10 CER 50.73.
This letter contains no commitments.
Please do not hesitate to contact Mr. Everett P. Perkins, Jr. (508) 830-8323, if there are any questions regarding this submittal.
Sincerely, David E. Ne yes Director, Regulatory and PerfOrmance Improvement : Licensee Event Report 2015-007-00, Single Main Steam Isolation Valve Closure Resulting in Automatic Reactor Scram (4 pages)
PNPS Letter 2.15.070 Page 2 of 2 cc:
Mr. Daniel H. Dorman Regional Administrator, Region 1 U.S. Nuclear Regulatory Commission 2100 Renaissance Blvd., Suite 100 King of Prussia, PA 19406-2713 Ms. Booma Venkataraman Project Manager Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Mail Stop O-8C2A Washington, DC 20555 USNRC Senior Resident Inspector Pilgrim Nuclear Power Station Letter Number 2.15.070 Licensee Event Report 2015-007-00 Single Main Steam Isolation Valve Closure Resulting in Automatic Reactor Scram (4 Pages)
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY 0MB: NO. 3150-0104 EXPIRES: 0113112017 (01-2014)
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 industr.
,L~t.*Z,*Send comments regardring burden estimate to the FOIA, Privacy and Informati on Collections
°...
IEN E V N R P R LR Branch (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by LICEN EE
~
EPORT
-~~I internet e-mail to Infocollects.Resource~nrc~gov, and to the Desk Officer, Office of Information and Regulatory Affairs, NEOB-10202, (3150-0104), Office of Management and Budget, Washington, DC 20503. If a means used to impose an information collection does not display a currently valid 0MB control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 3. PAGE Pilgrim Nuclear Power Station 05000293 1 OF 4
- 4. TITLE Single Main Steam Isolation Valve Closure Resulting in Automatic Reactor Scram
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED MONTH DAY YEAR YEAR ISEQUENTIAL REV FAIIYNM OKTNME NUMBER NO.
MONTH DAY YEAR N/NA FACILITY NAME DOcKET NUMBER 08 22 2015 2015 - 007 00 0
20 2015 N/NA
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMrI-TED PURSUANT TO THE REQUIREMENTS OF 10 CFR *: (Check all that apply)
D] 20.2201(b) f[I 20.2203(a)(3)(i)
I] 50.73(a)(2)(i)(C)
D 50.73(a)(2)(vii)
N D] 20.2201(d)
D 20.2203(a)(3)(ii)
I* 50.73(a)(2)(ii)(A)
- ] 50.73(a)(2)(viii)(A) 20.2203(a)(2)(t) 50.36(c)(1)(i)(A)
D 50.73(a)(2)(iii)
[* 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL D* 20.2203(a)(2)(ii) 50.36(c)(1 )(ii)(A)
[] 50.73(a)(2)(iv)(A)
I*
50.73(a)(2)(x) 100 20.2203(a)(2)(Jv)
- 50.46(a)(3)(ii)
J' 50.73(a)(2)(v)(B) 73.71 (a)(5)
D] 20.2203(a)(2)(v)
[* 50.73(a)(2)(i)(A)
[* 50.73(a)(2)(v)(C)
[*OTHER l 20.2203(a)(2)(vi)
[*
50.73(a)(2)(i)(B)
- ]
50.73(a)(2)(v)(O)
SpecfyiAbsactbeoornNRCForm366
- 12. LICENSEE CONTACT FOR THIS LER LICENSEE CONTACT ITELEPHONE NUMBER (Include Area Code)
Mr. Everett P. Perkins, Jr. - Regulatory Assurance Manager 1508-830-8323 rAU EOTAL
- MANU-REPORTABLE
CAUSE
SYSTEM COMPONENT FACTURER TO EPIX
CAUSE
SYSTEM COMPONENT FACTURER TO EPIX A
LD f PSF Y________
- 14. SUPPLEMENTAL REPORT EXPECTED 15 XETDMNH DAY YEAR D* YES (If yes, complete 15. EXPECTED SUBMISSION DATE)
NO DATE ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines)
On Saturday, August 22, 2015, at 1628 [EDT], with the reactor at 100% core thermal power the Pilgrim Nuclear Power Station experienced an automatic reactor scram due to Average Power Range Monitor High Flux signal from the rapid closure of one main steam isolation valve (MSIV). All plant systems responded as designed.
The Root Cause of this event is inadequate worker practices resulting in an excessive load being applied to the unistrut enclosed pneumatic line (during or prior to 2001) causing it to lay on a Main Steam Line subject to vibration. The excessive load caused an initiating crack in the nipple threads that over time resulted in a shear of the line.
The pneumatic supply line nipple was replaced and the line was re-supported.
This event posed no threat to public health and safety.
NRC FORM 366 (01-2014)U.S. NUCLEAR REGULATORY COMMISSIOI*
(01-2014)
LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET
- 1. FACILITY NAME
- 2. DOCKET
- 6. LER NUMBER
- 3. PAGE I YAR SEQUENTIAL REV NUMBER NO.
Pilgrim Nuclear Power Station 05000293 205 070_j2 OF 4
_7I0 BACKGROUND There are four Main Steam lines and each line contains two Main Steam Isolation Valves (MSIVs), one inboard valve located in the Drywell and one outboard valve located in the Steam Tunnel. The MSIVs are normally open during normal plant operation. Each MSIV is a 20" diameter Y-body globe valve with a pneumatic actuator to open and pneumatic & spring to close. The valve is a fail-safe closed design. A hydraulic cylinder sharing a common piston rod is used to control the closure speed via a needle valve. The safety function of these valves is to automatically close on a Primary Containment Isolation System Group 1 isolation signal.
EVENT DESCRIPTION
On Saturday, August 22, 2015, at 1628 [EDT], with the reactor at 100% core thermal power the Pilgrim Nuclear Power Station (PNPS) experienced an automatic reactor scram signal due to the rapid closure of one MSIV. Inboard MSIV AO-203-1 C had closed.
Primary Containment Isolation System Group II - Sampling Systems, Group VI - Reactor Water Cleanup System and Reactor Building Isolation System isolations occurred as expected due to the reactor scram at 100 percent power.
Reactor water level was restored to normal and maintained by the feedwater system. Reactor pressure control was maintained using the main turbine bypass valves. The plant was brought to a cold shutdown condition using the normal systems. All plant systems responded as designed to perform the safety functions.
The primary containment was de-inerted. A drywell entry was made to investigate the cause of the inboard MSIV AO-203-1 C closure. The pneumatic supply to the inboard MSIV AO-203-1 C valve control manifold was found sheared.
During the post trip review of the event, an anomaly was identified in the reactor protection system (RPS) channel A2. Reactor pressure exceeded the value for generating a reactor pressure trip signal. However, the channel A2 reactor high pressure trip was not recorded in the plant process computer log of the event. Due to the de-energize-to-actuate circuit design, once a scram trip signal is generated within the channel (in this case a reactor high flux signal), actuation of another signal has to be determined by other means, usually by review of the plant process computer log. Investigation of the circuit did not determine a definitive cause. The instrumentation loop was calibrated and a relay replaced prior to return to service. The most probable cause was oxidation on the relay contacts that provide the signal to the plant process computer. The relay contacts were burnished.
1U.S. NUCLEAR REGULATORY COMMISSION (01-2014)
LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET
- 1. FACILITY NAM~E
- 2. DOCKET
- 6. LER NUMBER
- 3. PAGE IIYEAR jSEQUENTIAL REV I
05 NUMBER NO.
Pilgrim Nuclear Power Station j05000293 00 0
3 OF 4
CAUSE OF THE EVENT
Direct Cause: The cause of the event is that the pneumatic supply to the inboard MSIV AO-203-1C valve control manifold was found sheared at a threaded nipple location.
Root Cause: The Root Cause of this event is inadequate worker practices resulting in an excessive load being applied to the unistrut enclosed pneumatic line (during or prior to 2001) causing it to lay on a Main Steam Line subjecting the line to vibration. The excessive load caused an initiating crack in the nipple threads that over time resulted in a shear of the line.
Contributing Cause
Inadequate identification and repair of adverse conditions. When the support failure was identified in 2001, an inadequate repair was performed.
CORRECTIVE ACTIONS
Completed:
- 1. The pneumatic supply nipple was replaced and the piping was re-supported.
- 2. A leak check of all fittings to the inboard MSIVs was performed.
Planned:
Additional corrective actions are captured in the corrective action program by Condition Report CR-PNP-2015-07285.
SAFETY CONSEQUENCES
UFSAR Appendix R.2.1.3.2 provides a summary of the initial core analysis for "Closure of One Main Steam Isolation Valve." A single MSIV closure with initial power is expected to cause a high neutron flux scram, increased reactor pressure, and increased fuel temperature. UFSAR Figure R.2-5 illustrates the predicted transient response including flux above the high neutron flux scram setpoint which causes the reactor scram.
No fuel damage or challenge to safety limits occurs.
Abnormal Operational Transients (AOT) are evaluated in the Updated Final Safety Analysis Report (UFSAR) to ensure that fuel cladding Minimum Critical Power Ratio (MCPR) Safety Limits are satisfied given transients caused by a single operator error or equipment malfunction. The spectrum of postulated initiating transient event categories is identified in U FSAR Section 14.3.2. The transient analysis contained in UFSAR Section 14 is supplemented by the original transient analysis contained in UFSAR Appendix R.
Closure of a single MSIV is an evaluated transient that is not required to be evaluated for each core reload because the transient is non-limiting. Only the most limiting AOT events affecting MCPR are addressed for each core reload to validate safety system settings and establish reactor fuel thermal limits.
This event is bounded by the analysis.U.S. NUCLEAR REGULATORY COMMISSIO!*
(01-2014)
LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET
- 1. FACILITY NAME
- 2. DOCKET
- 6. LER NUMBER
- 3. PAGE JEQEYEARRE SEUETILRE NUMBER NO.
Pilgrim Nuclear Power Station 05000293 4 OF 4
_2015~
007 00
REPORTABILITY
This report is submitted in accordance with 10 Code of Federal Regulations (CFR) 50.73(a)(2)(iv)(A) - System Actuation, Any event or condition that resulted in manual or automatic actuation of any of the systems listed in paragraph (a)(2)(iv)(B). The Reactor Protection System and Containment Isolation Signals are included in 10CFR50.73(a)(2)(iv)(B). The Reactor Protection System and Containment Isolation Signals were automatically actuated.
PREVIOUS EVENTS No recent single MSIV closure events have occurred at PNPS.
ENERGY INDUSTRY IDENTIFICATION SYSTEM (EIlS) CODES COMPONENTS CODES Pipe Fitting PSF SYSTEMS CODES Instrument Air System LD Main Steam System SB REFERENCES Condition Report CR-PNP-2015-07285, Single Main Steam Isolation Valve Closure Resulting in Automatic Reactor Scram Condition Report CR-PNP-2015-07295, Reactor Protection System Reactor High Pressure Channel A2 Trip Was Not Captured As Tripped by the Plant Process Computer SEn tergy EDeriy ENuclear ODerectionr c 60Reuaocky Hilleroradc mrvmn David E. Nayes, Director Regulatory & Performance Improvement October 20, 2015 U.S. Nuclear Regulatory Commission.
Attn: Document Control Desk Washington, DC 20555
SUBJECT:
Licensee Event Report 201 5-007-00, Single Main Steam Isolation Valve Closure Resulting in Automatic Reactor Scram Entergy Nuclear Operations, Inc.
Pilgrim Nuclear Power Station Docket No.: 50-293 License No.: DPR-35 LETTER NUMBER:
2.15.070
Dear Sir or Madam:
The enclosed Licensee Event Report (LER) 2015-007-00, Single Main Steam Isolation Valve Closure Resulting in Automatic Reactor Scram, is submitted in accordance with 10 CER 50.73.
This letter contains no commitments.
Please do not hesitate to contact Mr. Everett P. Perkins, Jr. (508) 830-8323, if there are any questions regarding this submittal.
Sincerely, David E. Ne yes Director, Regulatory and PerfOrmance Improvement : Licensee Event Report 2015-007-00, Single Main Steam Isolation Valve Closure Resulting in Automatic Reactor Scram (4 pages)
PNPS Letter 2.15.070 Page 2 of 2 cc:
Mr. Daniel H. Dorman Regional Administrator, Region 1 U.S. Nuclear Regulatory Commission 2100 Renaissance Blvd., Suite 100 King of Prussia, PA 19406-2713 Ms. Booma Venkataraman Project Manager Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Mail Stop O-8C2A Washington, DC 20555 USNRC Senior Resident Inspector Pilgrim Nuclear Power Station Letter Number 2.15.070 Licensee Event Report 2015-007-00 Single Main Steam Isolation Valve Closure Resulting in Automatic Reactor Scram (4 Pages)
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY 0MB: NO. 3150-0104 EXPIRES: 0113112017 (01-2014)
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 industr.
,L~t.*Z,*Send comments regardring burden estimate to the FOIA, Privacy and Informati on Collections
°...
IEN E V N R P R LR Branch (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by LICEN EE
~
EPORT
-~~I internet e-mail to Infocollects.Resource~nrc~gov, and to the Desk Officer, Office of Information and Regulatory Affairs, NEOB-10202, (3150-0104), Office of Management and Budget, Washington, DC 20503. If a means used to impose an information collection does not display a currently valid 0MB control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 3. PAGE Pilgrim Nuclear Power Station 05000293 1 OF 4
- 4. TITLE Single Main Steam Isolation Valve Closure Resulting in Automatic Reactor Scram
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED MONTH DAY YEAR YEAR ISEQUENTIAL REV FAIIYNM OKTNME NUMBER NO.
MONTH DAY YEAR N/NA FACILITY NAME DOcKET NUMBER 08 22 2015 2015 - 007 00 0
20 2015 N/NA
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMrI-TED PURSUANT TO THE REQUIREMENTS OF 10 CFR *: (Check all that apply)
D] 20.2201(b) f[I 20.2203(a)(3)(i)
I] 50.73(a)(2)(i)(C)
D 50.73(a)(2)(vii)
N D] 20.2201(d)
D 20.2203(a)(3)(ii)
I* 50.73(a)(2)(ii)(A)
- ] 50.73(a)(2)(viii)(A) 20.2203(a)(2)(t) 50.36(c)(1)(i)(A)
D 50.73(a)(2)(iii)
[* 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL D* 20.2203(a)(2)(ii) 50.36(c)(1 )(ii)(A)
[] 50.73(a)(2)(iv)(A)
I*
50.73(a)(2)(x) 100 20.2203(a)(2)(Jv)
- 50.46(a)(3)(ii)
J' 50.73(a)(2)(v)(B) 73.71 (a)(5)
D] 20.2203(a)(2)(v)
[* 50.73(a)(2)(i)(A)
[* 50.73(a)(2)(v)(C)
[*OTHER l 20.2203(a)(2)(vi)
[*
50.73(a)(2)(i)(B)
- ]
50.73(a)(2)(v)(O)
SpecfyiAbsactbeoornNRCForm366
- 12. LICENSEE CONTACT FOR THIS LER LICENSEE CONTACT ITELEPHONE NUMBER (Include Area Code)
Mr. Everett P. Perkins, Jr. - Regulatory Assurance Manager 1508-830-8323 rAU EOTAL
- MANU-REPORTABLE
CAUSE
SYSTEM COMPONENT FACTURER TO EPIX
CAUSE
SYSTEM COMPONENT FACTURER TO EPIX A
LD f PSF Y________
- 14. SUPPLEMENTAL REPORT EXPECTED 15 XETDMNH DAY YEAR D* YES (If yes, complete 15. EXPECTED SUBMISSION DATE)
NO DATE ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines)
On Saturday, August 22, 2015, at 1628 [EDT], with the reactor at 100% core thermal power the Pilgrim Nuclear Power Station experienced an automatic reactor scram due to Average Power Range Monitor High Flux signal from the rapid closure of one main steam isolation valve (MSIV). All plant systems responded as designed.
The Root Cause of this event is inadequate worker practices resulting in an excessive load being applied to the unistrut enclosed pneumatic line (during or prior to 2001) causing it to lay on a Main Steam Line subject to vibration. The excessive load caused an initiating crack in the nipple threads that over time resulted in a shear of the line.
The pneumatic supply line nipple was replaced and the line was re-supported.
This event posed no threat to public health and safety.
NRC FORM 366 (01-2014)U.S. NUCLEAR REGULATORY COMMISSIOI*
(01-2014)
LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET
- 1. FACILITY NAME
- 2. DOCKET
- 6. LER NUMBER
- 3. PAGE I YAR SEQUENTIAL REV NUMBER NO.
Pilgrim Nuclear Power Station 05000293 205 070_j2 OF 4
_7I0 BACKGROUND There are four Main Steam lines and each line contains two Main Steam Isolation Valves (MSIVs), one inboard valve located in the Drywell and one outboard valve located in the Steam Tunnel. The MSIVs are normally open during normal plant operation. Each MSIV is a 20" diameter Y-body globe valve with a pneumatic actuator to open and pneumatic & spring to close. The valve is a fail-safe closed design. A hydraulic cylinder sharing a common piston rod is used to control the closure speed via a needle valve. The safety function of these valves is to automatically close on a Primary Containment Isolation System Group 1 isolation signal.
EVENT DESCRIPTION
On Saturday, August 22, 2015, at 1628 [EDT], with the reactor at 100% core thermal power the Pilgrim Nuclear Power Station (PNPS) experienced an automatic reactor scram signal due to the rapid closure of one MSIV. Inboard MSIV AO-203-1 C had closed.
Primary Containment Isolation System Group II - Sampling Systems, Group VI - Reactor Water Cleanup System and Reactor Building Isolation System isolations occurred as expected due to the reactor scram at 100 percent power.
Reactor water level was restored to normal and maintained by the feedwater system. Reactor pressure control was maintained using the main turbine bypass valves. The plant was brought to a cold shutdown condition using the normal systems. All plant systems responded as designed to perform the safety functions.
The primary containment was de-inerted. A drywell entry was made to investigate the cause of the inboard MSIV AO-203-1 C closure. The pneumatic supply to the inboard MSIV AO-203-1 C valve control manifold was found sheared.
During the post trip review of the event, an anomaly was identified in the reactor protection system (RPS) channel A2. Reactor pressure exceeded the value for generating a reactor pressure trip signal. However, the channel A2 reactor high pressure trip was not recorded in the plant process computer log of the event. Due to the de-energize-to-actuate circuit design, once a scram trip signal is generated within the channel (in this case a reactor high flux signal), actuation of another signal has to be determined by other means, usually by review of the plant process computer log. Investigation of the circuit did not determine a definitive cause. The instrumentation loop was calibrated and a relay replaced prior to return to service. The most probable cause was oxidation on the relay contacts that provide the signal to the plant process computer. The relay contacts were burnished.
1U.S. NUCLEAR REGULATORY COMMISSION (01-2014)
LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET
- 1. FACILITY NAM~E
- 2. DOCKET
- 6. LER NUMBER
- 3. PAGE IIYEAR jSEQUENTIAL REV I
05 NUMBER NO.
Pilgrim Nuclear Power Station j05000293 00 0
3 OF 4
CAUSE OF THE EVENT
Direct Cause: The cause of the event is that the pneumatic supply to the inboard MSIV AO-203-1C valve control manifold was found sheared at a threaded nipple location.
Root Cause: The Root Cause of this event is inadequate worker practices resulting in an excessive load being applied to the unistrut enclosed pneumatic line (during or prior to 2001) causing it to lay on a Main Steam Line subjecting the line to vibration. The excessive load caused an initiating crack in the nipple threads that over time resulted in a shear of the line.
Contributing Cause
Inadequate identification and repair of adverse conditions. When the support failure was identified in 2001, an inadequate repair was performed.
CORRECTIVE ACTIONS
Completed:
- 1. The pneumatic supply nipple was replaced and the piping was re-supported.
- 2. A leak check of all fittings to the inboard MSIVs was performed.
Planned:
Additional corrective actions are captured in the corrective action program by Condition Report CR-PNP-2015-07285.
SAFETY CONSEQUENCES
UFSAR Appendix R.2.1.3.2 provides a summary of the initial core analysis for "Closure of One Main Steam Isolation Valve." A single MSIV closure with initial power is expected to cause a high neutron flux scram, increased reactor pressure, and increased fuel temperature. UFSAR Figure R.2-5 illustrates the predicted transient response including flux above the high neutron flux scram setpoint which causes the reactor scram.
No fuel damage or challenge to safety limits occurs.
Abnormal Operational Transients (AOT) are evaluated in the Updated Final Safety Analysis Report (UFSAR) to ensure that fuel cladding Minimum Critical Power Ratio (MCPR) Safety Limits are satisfied given transients caused by a single operator error or equipment malfunction. The spectrum of postulated initiating transient event categories is identified in U FSAR Section 14.3.2. The transient analysis contained in UFSAR Section 14 is supplemented by the original transient analysis contained in UFSAR Appendix R.
Closure of a single MSIV is an evaluated transient that is not required to be evaluated for each core reload because the transient is non-limiting. Only the most limiting AOT events affecting MCPR are addressed for each core reload to validate safety system settings and establish reactor fuel thermal limits.
This event is bounded by the analysis.U.S. NUCLEAR REGULATORY COMMISSIO!*
(01-2014)
LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET
- 1. FACILITY NAME
- 2. DOCKET
- 6. LER NUMBER
- 3. PAGE JEQEYEARRE SEUETILRE NUMBER NO.
Pilgrim Nuclear Power Station 05000293 4 OF 4
_2015~
007 00
REPORTABILITY
This report is submitted in accordance with 10 Code of Federal Regulations (CFR) 50.73(a)(2)(iv)(A) - System Actuation, Any event or condition that resulted in manual or automatic actuation of any of the systems listed in paragraph (a)(2)(iv)(B). The Reactor Protection System and Containment Isolation Signals are included in 10CFR50.73(a)(2)(iv)(B). The Reactor Protection System and Containment Isolation Signals were automatically actuated.
PREVIOUS EVENTS No recent single MSIV closure events have occurred at PNPS.
ENERGY INDUSTRY IDENTIFICATION SYSTEM (EIlS) CODES COMPONENTS CODES Pipe Fitting PSF SYSTEMS CODES Instrument Air System LD Main Steam System SB REFERENCES Condition Report CR-PNP-2015-07285, Single Main Steam Isolation Valve Closure Resulting in Automatic Reactor Scram Condition Report CR-PNP-2015-07295, Reactor Protection System Reactor High Pressure Channel A2 Trip Was Not Captured As Tripped by the Plant Process Computer