05000293/LER-2015-006, Regarding Ultimate Heat Sink and Salt Service Water System Declared Inoperable
| ML15289A231 | |
| Person / Time | |
|---|---|
| Site: | Pilgrim |
| Issue date: | 10/07/2015 |
| From: | Noyes D Entergy Nuclear Operations |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 2.15.066 LER 15-006-00 | |
| Download: ML15289A231 (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)(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 |
| 2932015006R00 - NRC Website | |
text
SEntergy Entergy Nuclear Operations, Inc.
Pilgrim Nuclear Power Station 600 Rocky Hill Road Plymouth, MA 02360 David E. Noyes, Director Regulatory & Performance Improvement October 7, 2015 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C. 20555
SUBJECT:
Entergy Nuclear Operations, Inc.
Pilgrim Nuclear Power Station Docket No.: 50-293 License No.: DPR-35 Licensee Event Report 201 5-006-00, Ultimate Heat Sink and Salt Service Water System Declared Inoperable LETTER NUMBER 2.15.066
Dear Sir or Madam:
The enclosed Licensee Event Report (LER) 201 5-006-00, "Ultimate Heat Sink and Salt Service Water System Declared Inoperable," is submitted in accordance with 10 CFR 50.73.
This letter contains no commitments.
Please do not hesitate to contact Mr. Everett P. (Chip) Perkins, Jr. at (508) 830-8323 if there are any questions regarding this submittal.
Sincerely, David E. Noyes Director, Regulatory & Performance Improvement DEN/pm
Attachment:
Licensee Event Report 201 5-006-00, Ultimate Heat Sink and Salt Service Water System Declared Inoperable (4 pages)
&-t I~j'~P
PNPS Letter 2.15.066 Page 2 of 2 cc:
Mr. Daniel H. Dorman Regional Administrator, Region I U.S. Nuclear Regulatory Commission 2100 Renaissance Boulevard, Suite 100 King of Prussia, PA 19406-1415 Ms. Booma Venkataraman, Project Manager Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Mail Stop O-8C2A Washington, DC 20555 NRC Resident Inspector Pilgrim Nuclear Power Station
ATTACHMENT To PNPS Letter 2.15.066 Licensee Event Report 201 5-006-00 Ultimate Heat Sink and Salt Service Water System Declared Inoperable (4 pages)
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY 0MB: NO. 3150-0104 EXPIRES: 01/31/2017 102-2014)
Estimated burden per response to comply with thin 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 LI CENSEE EVENT REPORT (LER)
Branch (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by (See Page 2 for required number of internet e-mail to lnfocollects.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 digits/characters for each block) 20503. If a means used to impose an information collection does not display a currentfy 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 Pilgrim Nuclear Power Station 05000293 1 OF 4
- 4. TITLE Ultimate Heat Sink and Salt Service Water System Declared Inoperable
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED MNH DY YA YER SEQUENTIAL REV FACILITY NAME DOCKET NUMBER MNH AY YA YER NUMBER NO.
MONTH DAY YEAR NA 05o000 FACILITY NAME DOCKET NUMBER 08 09 2015 2015 006 00 10 07 2015 NA 05000
- 9. OEPRAlING MODE
- 11. THIS REPORT IS SUBMrI-rED 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)
El 50.73(a)(2)(vii)
N El 20.2201(Cd)
El 20.2203(a)(3)(ii)
El 50.73(a)(2)(ii)(A)
El 50.73(a)(2)(viii)(A)
El 20.22D3(a)(1)
El 20.2203(a)(4)
El 50.73(a)(2)(ii)(B)
El 50.73(a)(2)(viii)(B)
__________E 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) 90 El 20.2203(a)(2)(iv)
El 50.46(a)(3)(ii)
[] 50.73(a)(2)(v)(B)
El 73.71 (a)(5)
El 20.2203(a)(2)(v)
El 50.73(a)(2)(i)(A)
El 50.73(a)(2)(v)(C)
El OTHER El 20.2203(a)(2)(vi)
El 50.73(a)(2)(i)(B)
[] 50.73(a)(2)(v)(D) specf nAbtatelwoinNCFr
- 12. LICENSEE CONTACT FOR THIS LER LICENSEE CONTACT TELEPHONE NUMER (Include Area Code)
Everett P. Perkins, Jr.
(508) 830-8323
- 13. COMPLETE ONE UNE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT
CAUSE
SYSTEM COMPONENT MANU-REPORTABLE I
CAUSE
SYSTEM COMPONENT MANU-REPORTABLE FACTURER TO EPIX I-FACTURER TO EPIX
- 14. SUPPLEMENTAL REPORT EXPECTED
- 15. EXPECTED MONTH DAY YEAR El YES (If yes, complete 15. EXPECTED SUBMISSION DATE)
[]
NO SUBMISSION
_____________________________________________DATE ABSTRACT (Limit to 1400 spaces, iLe., approximately 15 single-spaced typewrit ten lines)
On Sunday, August 9, 2015 at 1627 EDT with the reactor at 90% core thermal power (CTP), Pilgrim Nuclear Power Station (PNPS) declared the ultimate heat sink (UHS) and salt service water (SSW) system inoperable due to high sea water inlet temperatures greater than 750F and entered the Technical Specification (TS) 3.5.B.4 24-hour shutdown Limiting Condition for Operation (LCO) Action Statement. A maximum sea water inlet temperature reading of 75.030F was observed. The Action for TS 3.5.B.4 was exited at 1653 EDT (26 minutes elapsed time) based on sea water inlet temperature trending below the TS criterion. Plant systems and components operated as required.
The cause of the sea water inlet temperature exceeding the 75°F TS criterion was sustained increased sea water surface temperature in Cape Cod Bay due to summer weather conditions and recirculation of water from the plant's discharge due to wind and tidal conditions.
This condition posed no threat to the public health and safety.
NRC FORM 360 (02-2014)
BACKGROUND Cape Cod Bay is the UHS for PNPS. The circulating water system and the SSW system take sea water from Cape Cod Bay via the plant intake canal and intake structure and provide cooling water for various plant heat loads. These systems discharge the heated cooling water back into Cape Cod Bay via system discharge piping and the plant discharge canal.
The safety objective of the SSW system is to provide a heat sink for the reactor building closed cooling water (RBCCW) system under normal, transient, and accident conditions. The SSW system has five (5) SSW pumps and is designed with sufficient redundancy so that no single active system component failure can prevent the system from achieving the safety objective. The system is designed to continuously provide an adequate supply of cooling water to the secondary side of the RBCCW heat exchangers to meet the requirements of the RBCCW system under all conditions. The RBCCW system provides the necessary cooling requirements for the residual heat removal system and other safety-related systems.
The design and licensing basis maximum temperature of the UHS for PNPS is 75°F. TS Surveillance Requirement 4.5.B.4.2 requires verification of sea water inlet temperature to be -<750F in order to assure UHS operability. If the UHS is not operable, the plant is required to be in cold shutdown within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> per TS 3.5.B.4.
EVENT DESCRIPTION
On Sunday, August 9, 2015 at 1627 EDT with the reactor at 90% CTP, PNPS declared the UHS and SSW system inoperable due to high sea water inlet temperatures greater than 750F and entered the TS 3.5.B.4 24-hour shutdown LCO Action Statement. PNPS had reduced CTP by 10% at 1618 EDT in accordance with procedural guidance to address the rising inlet temperatures. A maximum sea water inlet temperature reading of 75.03°F was recorded. The Action Statement for TS 3.5.B.4 was exited at 1653 EDT (26 minutes elapsed time) based on sea water inlet temperature trending below the TS limit. Plant systems and components operated as required and no equipment failures occurred. The plant was not shutdown dlue to the short duration of the sea water temperature excursion. CTP was restored to 100% at 1938 EDT.
CAUSE OF THE EVENT
The cause of the sea water inlet temperature exceeding the 75°F TS criterion was sustained increased sea water surface temperature in Cape Cod Bay due to summer weather conditions and the contribution from recirculation of water from the plant's discharge due to wind and tidal conditions.
CORRECTIVE ACTIONS
A plant modification will be implemented to change the SSW loop temperature alarm setpoints from 73°F to 71°F.
Potential changes to Procedure 2.2.32, Salt Service Water System, are being evaluated to direct actions at a lower alarm setpoint for operations to initiate action based on the rate of temperature increase reaching or exceeding 3°F per hour.
SAFETY CONSEQUENCES
This condition posed no threat to the public health and safety. The short duration temperature excursion did not involve plant equipment failure.
This condition did not involve any radiological or industrial safety concerns, and as such, there were no radiological or industrial safety implications.
The potential safety significance of this event is associated with the UHS temperature and systems relied on to provide cooling during accident and transient conditions. The safety function of SSW is to transfer heat from all systems and components cooled by the RBCCW system to Cape Cod Bay by providing adequate cooling water flow to the secondary side of the RBCCW heat exchangers.
Design and accident analyses for the station have been performed with an assumption that the seawater temperature is limited to a maximum of 75°F.
Following an event in 2013 where the sea water inlet temperature exceeded 75°F, an engineering evaluation was performed to address the consequences of the temperature excursion and to determine whether the safety function would still have been fulfilled. This evaluation assumed an event where the UHS inlet temperatures exceeded 75°F and remained less than 78°F for short durations, with the 12-hour rolling average less than 75°F. This evaluation concluded all structures, systems, and components would be capable of performing their safety functions under the assumed conditions.
The temperature excursion that occurred on August 9, 2015 is bounded by that evaluation. Accordingly, the safety function of the UHS would have been satisfied based on the maximum temperature recorded and the short duration of the excursion.
REPORTABILITY
This event was reported to the NRC in accordance with 10 Code of Federal Regulations (CFR) 50.72(b)(3)(v)(D) as documented in Event Number 51301. This LER is submitted pursuant to 10 CFR 50.73(a)(2)(v)(B) and (D), Any event or condition that could have prevented the fulfillment of the safety function of structures or systems that are needed to remove residual heat and mitigate the consequences of an accident, respectively. Due to the temperature exceeding the TS limit, the UHS and SSW system used to remove residual heat and/or mitigate the consequences of an accident were declared inoperable and no redundant system or equipment was operable.
PREVIOUS EVENTS LER 2013-007-00, Ultimate Heat Sink and Salt Service Water System Declared Inoperable, reported a condition that occurred on two occasions in July 2013 (July 16, 2013 at 1652 EDT and July 17, 2013 at 1054 EDT) where the UHS and the SSW system were declared inoperable due to sea water inlet temperatures greater than 75°F. During these events, a maximum sea water inlet temperature reading of 75.50 F was observed and the maximum duration for either event was 5.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />. (CR-PNP-2013-5246 and CR-PNP-2013-5262)
ENERGY INDUSTRY IDENTIFICATION SYSTEM (EllS) CODES The EIlS codes for components and systems referenced in this report are as follows:
SYSTEMS CODES Ultimate Heat Sink (UHS) System (Cape Cod Bay)
BS REFERENCES CR-PNP-201 5-6987, Local salt service water temperature exceeded 74.9°F CR-PNP-2014-1229, Ultimate heat sink safety system functional failure evaluation
BACKGROUND Cape Cod Bay is the UHS for PNPS. The circulating water system and the SSW system take sea water from Cape Cod Bay via the plant intake canal and intake structure and provide cooling water for various plant heat loads. These systems discharge the heated cooling water back into Cape Cod Bay via system discharge piping and the plant discharge canal.
The safety objective of the SSW system is to provide a heat sink for the reactor building closed cooling water (RBCCW) system under normal, transient, and accident conditions. The SSW system has five (5) SSW pumps and is designed with sufficient redundancy so that no single active system component failure can prevent the system from achieving the safety objective. The system is designed to continuously provide an adequate supply of cooling water to the secondary side of the RBCCW heat exchangers to meet the requirements of the RBCCW system under all conditions. The RBCCW system provides the necessary cooling requirements for the residual heat removal system and other safety-related systems.
The design and licensing basis maximum temperature of the UHS for PNPS is 75°F. TS Surveillance Requirement 4.5.B.4.2 requires verification of sea water inlet temperature to be -<750F in order to assure UHS operability. If the UHS is not operable, the plant is required to be in cold shutdown within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> per TS 3.5.B.4.
EVENT DESCRIPTION
On Sunday, August 9, 2015 at 1627 EDT with the reactor at 90% CTP, PNPS declared the UHS and SSW system inoperable due to high sea water inlet temperatures greater than 750F and entered the TS 3.5.B.4 24-hour shutdown LCO Action Statement. PNPS had reduced CTP by 10% at 1618 EDT in accordance with procedural guidance to address the rising inlet temperatures. A maximum sea water inlet temperature reading of 75.03°F was recorded. The Action Statement for TS 3.5.B.4 was exited at 1653 EDT (26 minutes elapsed time) based on sea water inlet temperature trending below the TS limit. Plant systems and components operated as required and no equipment failures occurred. The plant was not shutdown dlue to the short duration of the sea water temperature excursion. CTP was restored to 100% at 1938 EDT.
CAUSE OF THE EVENT
The cause of the sea water inlet temperature exceeding the 75°F TS criterion was sustained increased sea water surface temperature in Cape Cod Bay due to summer weather conditions and the contribution from recirculation of water from the plant's discharge due to wind and tidal conditions.
CORRECTIVE ACTIONS
A plant modification will be implemented to change the SSW loop temperature alarm setpoints from 73°F to 71°F.
Potential changes to Procedure 2.2.32, Salt Service Water System, are being evaluated to direct actions at a lower alarm setpoint for operations to initiate action based on the rate of temperature increase reaching or exceeding 3°F per hour.
SAFETY CONSEQUENCES
This condition posed no threat to the public health and safety. The short duration temperature excursion did not involve plant equipment failure.
This condition did not involve any radiological or industrial safety concerns, and as such, there were no radiological or industrial safety implications.
The potential safety significance of this event is associated with the UHS temperature and systems relied on to provide cooling during accident and transient conditions. The safety function of SSW is to transfer heat from all systems and components cooled by the RBCCW system to Cape Cod Bay by providing adequate cooling water flow to the secondary side of the RBCCW heat exchangers.
Design and accident analyses for the station have been performed with an assumption that the seawater temperature is limited to a maximum of 75°F.
Following an event in 2013 where the sea water inlet temperature exceeded 75°F, an engineering evaluation was performed to address the consequences of the temperature excursion and to determine whether the safety function would still have been fulfilled. This evaluation assumed an event where the UHS inlet temperatures exceeded 75°F and remained less than 78°F for short durations, with the 12-hour rolling average less than 75°F. This evaluation concluded all structures, systems, and components would be capable of performing their safety functions under the assumed conditions.
The temperature excursion that occurred on August 9, 2015 is bounded by that evaluation. Accordingly, the safety function of the UHS would have been satisfied based on the maximum temperature recorded and the short duration of the excursion.
REPORTABILITY
This event was reported to the NRC in accordance with 10 Code of Federal Regulations (CFR) 50.72(b)(3)(v)(D) as documented in Event Number 51301. This LER is submitted pursuant to 10 CFR 50.73(a)(2)(v)(B) and (D), Any event or condition that could have prevented the fulfillment of the safety function of structures or systems that are needed to remove residual heat and mitigate the consequences of an accident, respectively. Due to the temperature exceeding the TS limit, the UHS and SSW system used to remove residual heat and/or mitigate the consequences of an accident were declared inoperable and no redundant system or equipment was operable.
PREVIOUS EVENTS LER 2013-007-00, Ultimate Heat Sink and Salt Service Water System Declared Inoperable, reported a condition that occurred on two occasions in July 2013 (July 16, 2013 at 1652 EDT and July 17, 2013 at 1054 EDT) where the UHS and the SSW system were declared inoperable due to sea water inlet temperatures greater than 75°F. During these events, a maximum sea water inlet temperature reading of 75.50 F was observed and the maximum duration for either event was 5.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />. (CR-PNP-2013-5246 and CR-PNP-2013-5262)
ENERGY INDUSTRY IDENTIFICATION SYSTEM (EllS) CODES The EIlS codes for components and systems referenced in this report are as follows:
SYSTEMS CODES Ultimate Heat Sink (UHS) System (Cape Cod Bay)
BS REFERENCES CR-PNP-201 5-6987, Local salt service water temperature exceeded 74.9°F CR-PNP-2014-1229, Ultimate heat sink safety system functional failure evaluation