05000334/LER-2010-001, Regarding Void in Emergency Core Cooling System Pump Suction Header Results in Entry Into Technical Specification LCO 3.0.3
| ML103000042 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley (DPR-066) |
| Issue date: | 10/21/2010 |
| From: | Harden P FirstEnergy Nuclear Operating Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| L-10-292 LER 10-001-00 | |
| Download: ML103000042 (6) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(v)(A), Loss of Safety Function - Shutdown the Reactor 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(i) 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)(B), Loss of Safety Function - Remove Residual Heat 10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown |
| 3342010001R00 - NRC Website | |
text
FENOC FirstEnergy Nuclear Operating*Company Beaver Valley Power Station P.O. Box 4 Shippingport, PA 15077 Paul A. Harden Site Vice President 724-682-5234 Fax: 724-643-8069 October 21, 2010 L-1 0-292 10 CFR 50.73 ATTN: Document Control Desk U. S. Nuclear Regulatory Commission Washington, DC 20555-0001
SUBJECT:
Beaver Valley Power Station, Unrit No. 1 Docket No. 50-334, License No. DPR-66 LER 2010-001-00 Enclosed is Licensee Event Report (LER) 2010-001-00, "Void in Emergency Core Cooling System Pump Suction Header Results in Entry into Technical Specification LCO 3.0.3." This event is being reported in accordance with 10 CFR 50.73(a)(2)(i)(B),
10 CFR 50.73(a)(2)(v)(A), 10 CFR'50.73(a)(2)(v)(D) and 10 CFR 50.73(a)(2)(vii).
There are no regulatory commitments contained in this submittal. Any actions discussed in this document that represent intended or planned actions are described for the NRC's information, and are not regulatory commitments.
If there are any questions or if additional information is required, please contact Mr. Brian T. Tuite, Manager, Regulatory Compliance at 724-682-4284.
Attachment c:
Mr. W. M. Dean, NRC Region I Administrator Mr.D. L. Werkheiser, NRC Senior Resident Inspector Ms. N. S. Morgan, NRR Project Manager INPO Records Center (via electronic image)
Mr. L. E. Ryan (BRP/DEP)
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB NO. 3150-0104 EXPIRES 08/31/2010 (9-2007)
, the NRC may digits/characters fnot conduct or sponsor, and a person is not required to respond to, the information collection.
- 3. PAGE Beaver Valley Power Station Unit Number 1 05000334 1 of 5
- 4. TITLE Void in Emergency Core Cooling System Pump Suction Header Results in Entry into Technical Specification LCO 3.0.3
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED M SEQUENTIAL REV FACILITY NAME DOCKET NUMBER MONTH DAY YEAR YER NUMBER [NO MONTH DAY YEAR None 08 26 2010 2010 001 00 10 21 2010 FACILITY NAME DOCKET NUMBER
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply)
E] 20.2201(b)
El 20.2203(a)(3)(i)
El 50.73(a)(2)(i)(C)
Z 50.73(a)(2)(vii)
E E] 20.2201(d)
El 20.2203(a)(3)(ii)
E] 50.73(a)(2)(ii)(A)
[] 50.73(a)(2)(viii)(A)
E] 20.2203(a)(1)
El 20.2203(a)(4)
E] 50.73(a)(2)(ii)(B)
El 50.73(a)(2)(viii)(B)
E] 20.2203(a)(2)(i)
E] 50.36(c)(1)(i)(A)
E] 50.73(a)(2)(iii)
D] 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL E] 20.2203(a)(2)(ii)
[] 50.36(c)(1)(ii)(A)
E] 50.73(a)(2)(iv)(A)
El 50.73(a)(2)(x)
E] 20.2203(a)(2)(iii)
,E.50.36(c)(2) 0 50.73(a)(2)(v)(A)
[] 73.71(a)(4) 100 %
E] 20.2203(a)(2)(iv)
[
50.46(a)(3)(ii)
E] 50.73(a)(2)(v)(B)
El 73.71(a)(5)
E) 20.2203(a)(2)(v)
[
50.73(a)(2)(i)(A)
El 50.73(a)(2)(v)(C)
El OTHER Specify in Abstract below
_ 20.2203(a)(2)(vi)
[
50.73(a)(2)(i)(B)
[
50.73(a)(2)(v)(D) or in the cleared pump/pipes to migrate upwards into the operating charging suction header.
This pump recovery procedure was used multiple times in past years without recognizing any adverse conditions because the existing high point vent was used to vent off the air prior to taking UT measurements. A recent procedure change resulted in the order of venting and UT testing being altered during a HHSI pump recovery, and this was the first time that the-UT was performed before venting of-the common -suction. header, which allowed the void to be discovered this time.
Applicable ECCS pump recovery procedure has beenplaced on administrative hold pending completion of corrective actions.
CAUSE OF-EVENT The cause of this event is the charging pump suction piping layout at BVPS Unit 1 is conducive to allowing a void to migrate to the charging pump common suction header during a fill and vent procedure. There is no proper high point vent within the suction side clearance boundary for each of the three HHSI/charging pumps which does not allow fill and vent without void migration to the suction header. Currently the only available high point vent is not sufficient in this case because the vent is on a common header to all three HHSI pumps outside the clearance boundary. {One charging pump operates continuously when at power.} A pre-conditioned mindset existed for the individuals that performed the previous operations procedure reviews of Emergency Core Cooling System procedures for potential gas voiding issues that this procedure was acceptable based on successful past performances with no anomalies noted.
A similar design/configuration anomaly does not exist for the BVPS Unit 2 HHSI/charging system suction header.
ANALYSIS OF EVENT
Both trains of HHSI required to be operable pursuant to BVPS Unit 1 Technical Specification 3.5.2 were not fully capable of performing to design basis bounding requirements. With both trains of HHSI being declared inoperable due to a gas void in the common suction header leading to both HHSI pumps, this event/condition is reportable as an event that could have prevented the fulfillment of a safety function which adversely affects the ability to safely shutdown the plant { 1 OCFR50.73(a)(2)(v)(A) }, the ability to mitigate the consequences of an accident { 10CFR50.73(a)(2)(v)(D) }, and reportable as a single condition that caused two independent trains to be inoperable
{ 10CFR50.73(a)(2)(vii) }.
Notwithstanding the above, an Engineering evaluation was performed which showed that both HHSI trains could have performed their safety function during-a postulated design basis accident, using a best-estimate assessment of plant parameters for a void of the size measured in this event located in the common charging header. In addition, since this same fill and vent process has been used in the past, a best-estimate evaluation of a postulated void from -a bounding scenario where the entire void volume from a cleared and drained HHSI pump/piping migrates into the common charging suction header also showed acceptable HHSI train capability. Therefore, this event is not reportable pursuant to IOCFR50.73(a)(2)(ii)(B) as an unanalyzed condition that significantly degraded plant safety..
This event was previously reported as an event that could have prevented the fulfillment of -a safety function-pursuant to 10CFR 50.72(b)(3)(v)(A)/(b)(3)(v)(D) at 2222 hours0.0257 days <br />0.617 hours <br />0.00367 weeks <br />8.45471e-4 months <br /> on 08/26/2010 (Event Notification 46208). However, the initial reportability of this event in EN 46208 for 10 CFR 50.72(b)(3)(ii)(B) is retracted, with the same basis as provided above for 10 CFR 50.73(a)(2)(ii)(B).
This event is also reportable pursuant to 10 CFR 50.73(a)(2)(i)(B) as an event/condition prohibited by plant Technical Specifications. BVPS Unit 1 Technical Specification 3.5.2, "ECCS-Operating", Required Action C.1 requires the entry into LCO 3.0.3 immediately when less than 100 percent of ECCS flow equivalent to a single operable ECCS train is available.
TS LCO 3.0.3 requires action to be initiated within one hour to place the plant in a Mode or other condition in which the condition of operation is not applicable. The HHSI System was made inoperable longer-than one hour when the HHSI fill and vent procedure introduced an unacceptable airvoid into the common HHSI suction pipe header during this event and likely during past performances. Therefore, BVPS Unit No. 1 was in a condition prohibited by plant Technical Specifications whenever the plant was in this unacceptable HHSI condition for longer than one hour.
The plant ri-sk associated with the BVPS Unit 1 HHSI pump suction header void event that occurred on 08/26/2010 and with prior drained HHSI pump recovery events is considered to be very low. This is based upon an Engineering technical assessment, which concluded that the HHSI pump capability would not have been significantly challenged by the measured void using best-estimate considerations. Therefore, the conditional probability of the HHSI pumps failing due to the void is negligible, and the increase in risk is insignificant. Therefore, the safety significance of the HHSI pump suction header void event was very low.
CORRECTIVE ACTIONS
- 1. A solution will be developed to allow filling/venting in order to return a charging pump to service while at power in a manner that does not challenge the operability of the system.
This may involve a design change to add a new vent valve between the suction isolation valve in the piping for-each of the three charging pumps. Upon implementation of the solution, the fill and vent operations procedure will be revised to incorporate this solution.
- 2. Operations procedures at both BVPS Unit 1 and Unit 2 that fill and vent the ECCS systems will be reviewed, with a focus on prevention of air void migration into operating parts of systems. These procedure reviews will look at elevation differences, the order of
_UT and venting sequence, and the manipulation of valves outside of the clearance boundary.
- 3. A plant operating experience report has issued on this event (OE 32074).
- 4. The site procedure on procedure cross-discipline review guidance will be revised to ensure fill and vent procedures on ECCS systems include a review of applicable isometric drawings (or physical plant walk down) to ensure the proposed procedure modification will not adversely migrate or introduce a gas void.
Completion of the above and other corrective actions are being tracked through the BVPS corrective action program.
PREVIOUS SIMILAR EVENTS
Gas voids have been found several times in both BVPS Units' HHSI systems within the last five years, pursuant to surveillances performed for normal post-maintenance testing and to address both industry and regulatory initiatives on gas voids. However, no voids previously identified were above the applicable gas void size limit such that the HHSI system(s) needed to be declared inoperable.
CR 10-81835/10-81969