05000261/LER-2004-001, Regarding Both Trains of High Pressure Safety Injection Inoperable for Approximately 25 Minutes
| ML041530084 | |
| Person / Time | |
|---|---|
| Site: | Robinson  |
| Issue date: | 05/26/2004 |
| From: | Cleary T Progress Energy Carolinas |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| RNP-RA/04-0062 LER 04-001-00 | |
| Download: ML041530084 (8) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 10 CFR 50.73(a)(2)(ix)(A) 10 CFR 50.73(a)(2)(iii) 10 CFR 50.73(a)(2)(x) 10 CFR 50.73(a)(2)(iv)(A), System Actuation 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) 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)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2)(viii)(A) 10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded 10 CFR 50.73(a)(2)(viii)(B) |
| 2612004001R00 - NRC Website | |
text
¢j Progress Energy MAY 2 6 2004 Serial: RNP-RA/04-0062 United States Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555 H. B. ROBINSON STEAM ELECTRIC PLANT, UNIT NO. 2 DOCKET NO. 50-261/LICENSE NO. DPR-23 LICENSEE EVENT REPORT NO. 2004-001-00 BOTH TRAINS OF HIGH PRESSURE SAFETY INJECTION INOPERABLE FOR APPROXIMATELY 25 MINUTES Ladies and Gentlemen:
The attached Licensee Event Report is submitted in accordance with the requirements of 10 CFR 50.73. Should you have any questions regarding this matter, please contact Mr. C. T. Baucom, Supervisor - Licensing/Regulatory Programs, at (843) 857-1253.
Sincerely, ioty Cleay Plant General Manager H. B. Robinson Steam Electric Plant, Unit No. 2 CTB/cac Attachment c:
Mr. L. A. Reyes, NRC, Region II Mr. C. P. Patel, NRC, NRR NRC Resident Inspector, HBRSEP Progress Energy Carolinas. Inc.
Robinson Nuclear Plant 3581 West Entrance Road Hartsville, SC 29550 I-Z--
ac-
NRC FORM 366 U.S. NUCLEAR REGULATORY APPROVED BY OMB NO. 3150-0104 EXPIRES 7-31-2004 (7.2001)
COMMISSION
, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
FACILITY NAME (1)
DOCKET NUMBER (2)
PAGE (3)
H. B. Robinson Steam Electric Plant, Unit No. 2 05000261 1 OF 7
TITLE (4)
Both Trains of High Pressure Safety Injection Inoperable for Approximately 25 Minutes EVENT DATE (5)
LER NUMBER (6)
REPORT DATE (7)
OTHER FACILIES INVOLVED (8)
FACILITY NAME DOCKET NUMBER MO DAY YEAR YEAR SNTIAL REV MO DAY YEAR FACILITY NAME DOCKET NUMBER 03 28 2004 2004 - 001
- - 00 05 26 2004 OPERATING THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR : Check all that a 11 MODE (9) 1
_ 20.2201 (b) 20.2203(a)(3)(ii)
X 50.73(a)(2)(ii)(B)
_ 50.73(a)(2)(ix)(A)
POWER 20.2201 (d) 20.2203(a)(4) 50.73(a)(2)(iii) 50.73(a)(2)(x)
LEVEL (10) 100% _
20.2203(a) 1) 50.36(c)(1)(i)(A) 50.73(a)(2)(iv)(A) 73.71 (a)(4) 20.2203(a)(2)(i) 50.36(c)(1)(ii)(A) 50.73(a)(2)(v)(A) 173.71 (a)(5) 20.2203(a)(2)(ii) 50.36(c)(2)
X_
50.73(a)(2)(v)(B) j OTHER
_20.2203(a)(2)(iii)
_50.46(_
50.73(a)(2)
Specify in Abstract below or in
._ 20.2203(a)(2)(iv) 50.73(a)(2)(i)(A)
X 50.73(a)(2)(v)(D) 20.2203(a)(2)(v) 50.73(a)(2)(i)(B) 50.73(a)(2)(vii) 20.2203(a)(2)(vi) 50.73(a)(2)(i)(C) 50.73(a)(2)(viii)(A) 20.2203(a)(3)(i) 50.73(a)(2)(ii)(A) 50.73(a)(2)(viii)(B)
LICENSEE CONTACT FOR THIS LER (12)
NAME TELEPHONE NUMBER (Include Area Code)
C. T. Baucom 1
843-857-1253 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13) l
CAUSE
SYSTEM COMPONENT MANURER TO EPiXR i
CAUSE
SYSTEM COMPONENT lFACTU RER TOAE X
BQ P
W318 Y
L M
D YEA SUPPLEMENTAL REPORT EXPECTED (14)
ED MONTH DAY YES (If yes, complete EXPECTED SUBMISSION DATE).
X I NO DATE (15) l l
l l
ABSTRACT (Lmit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines) (16)
At approximately 1343 hours0.0155 days <br />0.373 hours <br />0.00222 weeks <br />5.110115e-4 months <br /> on March 27, 2004, during a routine hand-rotation check of the "C" high pressure safety injection (HPSI) pump, it was discovered that the pump shaft was exhibiting some binding. At the time, the 'C" HPSI pump was in service as the "B" Train HPSI pump. The 'C" HPSI pump was declared inoperable and Condition A of Technical Specifications Limiting Condition for Operation (LCO) 3.5.2 was entered. This LCO Condition requires restoration of the inoperable HPSI train within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. At that time, the "B" HPSI pump was in service as the Train "A" HPSI pump. The 'A" HPSI pump was out-of-service due to a previously discovered condition of minor flange leakage near two of the casing bolts. It was determined that the "A" pump could be restored to operable status and placed back in service to restore two trains of HPSI.
In order to do so, the "B" HPSI pump was removed from service as the Train "A" pump and placed in service as the Train "B" pump.
Therefore, at 1026 hours0.0119 days <br />0.285 hours <br />0.0017 weeks <br />3.90393e-4 months <br /> on March 28, 2004, for approximately 25 minutes, during the process of placing the "B' HPSI pump in service on Train "B," which was necessary to allow the "A" HPSI pump to be returned to service, there was no HPSI pump automatically available to provide HPSI to the Reactor Coolant System. The cause of the event was the sequence of mechanical equipment failures that necessitated the transfer of the "B" HPSI pump from Train "A" to Train "B." This condition is being reported in accordance with 50.73(a)(2)(ii)(B) and 50.73(a)(2)(v)(D).
NRC FORM 366 (7-2001)
(if more space is required, use additional copies of (If more space is required, use additional copies of (If more space is required, use additional copies of (if more space is required, use additional copies of NRC Form 36WA) (17)
HPSI system was inoperable, if one of these events had occurred, the HPSI system would not have automatically operated as analyzed for these events. Depending on the severity of the accident, it is likely the operators would have been able to restore the system in time to maintain the fission product barriers within the limits described in the UFSAR. This is based on the operators being actively in the process of manipulating the breakers and controls to restore the "B" HPSI pump to operational status and, if needed, the pump could have been restored to either 480 volt emergency bus (El Bus or E2 Bus).
A probabilistic safety evaluation was conducted for the inoperability of the HPSI system. This review is summarized as follows:
The Conditional Core Damage Probability (CCDP) associated with an 11 minute unavailability of all HPSI was estimated using the HBRSEP, Unit No. 2, Equipment Out-of-Service (EOOS) model, which utilizes the EPRI EOOS software.
Both trains of HPSI were set in the model to be out-of-service and a Core Damage Frequency (CDF) of 1.13E-3 resulted.
Note that this result is highly conservative because the "B" HPSI pump and possibly the "A" HPSI pump could have been placed in service quickly had there been an actual demand.
It is therefore conservative to assume that the pumps were truly unavailable.
Based on this information, the CCDP for the HPSI system unavailability period is estimated as 2.36E-8.
It is possible that the plant could have continued in operation with only Train "A" of HPSI in service (via the "B" HPSI pump) while Train "B" ("C" HPSI pump) was repaired.
If it is assumed that a minimum period of 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> would have been required to repair and restore the "C" HPSI pump, the risk associated with this option is estimated to be 1.33E-7. This value is greater than the CCDP of 2.36E-8 calculated above for the actions which were taken. Therefore, based on the CCDP estimates, the action to realign the HPSI pumps did not result in an inappropriate increase in risk.
An alternate calculation can be performed to compare the risk in terms of Incremental Core Damage Probability (ICDP). The ICDP associated with the 11 minute HPSI unavailability is calculated to be 2.28E-8. The ICDP associated with a 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> repair to the "C" HPSI pump is calculated to be 2.36E-8. This calculation also supports the conclusion that the action to realign the HPSI pumps did not result in an inappropriate increase in risk.
(if more space is required, use additional copies of (if more space is required, use additional copies of NRC Form 366A) (17) pumps are being managed through the work management process, commensurate with the safety importance of this system. The repair to the "C" HPSI pump is currently planned for completion by June 17, 2004. The repair to the "A" HPSI pump is currently planned for completion by August 12, 2004. It should be further noted that the "A" HPSI pump is operable and the planned corrective maintenance for the repair of the minor flange leakage is not required for pump operability. The "C" HPSI pump has been completely refurbished by an off-site vendor and is in the process of being re-installed and returned to service.
V.
ADDITIONAL INFORMATION
A. Failed Component Information:
The "A" and "C" HPSI pumps are Worthington Corporation Model 3WTS811.
B. Previous Similar Events
A review of recent events at HBRSEP, Unit No. 2, for similar conditions that could have prevented the fulfillment of a safety function was conducted. No similar events were found in which a safety system was made inoperable due to equipment failures and subsequent restoration methods.