05000282/LER-2007-005, From Prairie Island, Unit 1 Regarding One Train of Scws Inoperable Longer than Allowed by Technical Specifications

From Prairie Island, Unit 1 Regarding One Train of Scws Inoperable Longer than Allowed by Technical Specifications

ML080380300
Person / Time
Site:	Prairie Island
Issue date:	02/07/2008
From:	Wadley M Nuclear Management Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
L-PI-08-008 LER 07-005-00
Download: ML080380300 (6)

LER-2007-005, From Prairie Island, Unit 1 Regarding One Train of Scws Inoperable Longer than Allowed by Technical Specifications

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(1) 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(v), Loss of Safety Function
2822007005R00 - NRC Website

text

Prairie lsland Nuclear Generating Plant Operated by Nuclear Management Company, LLC February 7, 2008 L-PI-08-008 10 CFR 50.73 U S Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Prairie lsland Nuclear Generating Plant Unit 1 Docket 50-282 License No. DPR-42 LER 1-07-05, One Train of Safeguards Chilled Water Svstem (SCWS) Inoperable Longer than Allowed bv Technical Specifications Nuclear Management Company, LLC (NMC) herewith encloses Licensee Event Report (LER) 1-07-05. The LER describes Prairie lsland Nuclear Generating Plant Unit 1 operation in a condition prohibited by Technical Specifications when one train of safeguards chilled water system was discovered to have been inoperable for longer than allowed by Technical Specifications.

Summary of Commitments This letter contains one new commitment and no changes to existing commitments:

NMC will supplement this LER upon completion of the root cause evaluation for this event.

Michael D. Wadley 4.

Site Vice President, Prairie lsland Nuclear Generating Plant Nuclear Management Company, LLC Enclosure cc:

Administrator, Region Ill, USNRC Project Manager, Prairie Island, USNRC Resident Inspector, Prairie Island, USNRC Department of Commerce, State of Minnesota 171 7 Wakonade Drive East Welch, Minnesota 55089-9642 Telephone: 651.388.1 121

ENCLOSURE LICENSEE EVENT REPORT 1-07-05 4 Pages Follow

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION (9 2007)

LICENSEE EVENT REPORT (LER)

(See reverse for required number of d~g~tslcharacters for each block)

1. FACILITY NAME Pra~r~e Island Nuclear Generat~ng Plant Un~t 1 APPROVED BY OMB NO 3150-0104 EXPIRES 08/31/2010 Estimated burden per response to comply wlth thls mandatory collectlon 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 llcenslng process and fed back to Industry Send comments regarding burden estlmate to the Records and FOlAlPrivacy Sewlce Branch (T-5 F52), U S Nuclear Regulatory Comm~ss~on, Washlngton, DC 20555-0001, or by Internet e-mall to ~nfocollects@nrc gov, and to the Desk Officer, Office of lnformatlon and Regulatory Affalrs, NEOB-10202, (3150-0066), Office of Management and Budget, Washington, DC 20503 If a means used to lrnpose an information collect~on does not dlsplay a currently valld OMB control number, the NRC may not conduct or sponsor, and a person is not requlred to respond to, the lnformation collectlon

2. DOCKET NUMBER 05000282

4. TITLE One Tram of SCWS Inoperable Longer than Allowed by Technical Spec~ficat~ons

3. PAGE 1 of4

5. EVENT DATE MONTH 12

6. LER NUMBER NAME Jeff KIVI

11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR 5: (Check all that apply) 20 2201(b) 20 2203(a)(3)(1) 50 73(a)(2)(1)(C) 50 73(a)(2)(vll) 20 2201(d) 20 2203(a)(3)(11) 50 73(a)(2)(11)(A) 50 73(a)(2)(v111)(A) 20 2203(a)(I)

IJ 20 2203(a)(4) 50 73(a)(2)(11)(6) 50 73(a)(2)(v111)(B) 20 2203(a)(2)(1) 50 36(c)(l )(l)(A) 50 73(a)(2)(111) 50 73(a)(2)(1x)(A) 20 2203(a)(2)(11)

IJ 50 36(c)(l)(11)(A) 50 73(a)(2)(1v)(A)

IJ 50 73(a)(2)(x) 20 2203(a)(2)(111) 50 36(c)(2) 5 0 73(a)(2)(v)(A) 73 71 (a)(4) 20 2203(a)(2)(1v) 50 46(a)(3)(11) 50 73(a)(2)(v)(B) 7 3 71 (a)(5) 20 2203(a)(2)(v) 50 73(4(2)(1)(A) 50 73(a)(2)(v)(C)

OTHER 20 2203(a)(2)(v1) 50.73(a)(2)(1)(6) 50 73(a)(2)(v)(D)

Spectfy In Abstract below or In NRC Fp~p) 366A

12. LICENSEE CONTACT FOR THlS LER

9. OPERATING MODE 1

10. POWER LEVEL 100 DAY 12 YEAR TELEPHONE NUMBER (Include Area Code) 651.388.1 121 YEAR 2007

7. REPORT DATE 2007 0 SEQUENTIAL NUMBER MONTH 02

8. OTHER FACILITIES INVOLVED REV NO FACILITY NAME Prairie Island Unit FACILITY NAME DAY 7

DOCKET NUMBER 05000306 DOCKET NUMBER REPORTABLE TO EPlX YEAR 2008

CAUSE

YEAR 2008 ABSTRACT (Limit to 1400 spaces, r e, approximately 15 single-spaced typewritten lines)

On October 1, 2007, Nuclear Management Company, LLC (NMC) staff identified leakage under the insulation on the 121 (Train A shared between Units 1 and 2) Control Room Chiller. The leakage was attributed to a flange leak and a work order was initiated. On December 11, 2007, NMC staff determined that the leakage was not due to a flange leak, but due to a through wall leak on the associated flexible spool piece. On December 12, 2007, NMC staff determined the 121 Control Room Chiller was inoperable as a result of the leaking flexible spool piece. Thus, the 121 Control Room Chiller and Train A Safeguards Chilled Water System (SCWS) was inoperable for more than 60 days. Technical Specification (TS) 3.7.1 1 (SCWS) Condition A requires that an inoperable SCWS loop be returned to operable status within 30 days. TS 3.7.1 1 Condition B requires that ~f Condition A is not met, both units must be in Mode 3 in 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and Mode 5 in 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. Since neither un~t was shutdown pursuant to TS 3.7.1 1 Condition B, this event is being reported in accordance with 10 CFR 50 73(a)(2)(i)(B) as a condition prohibited by TS.

The leaking flexible spool piece was replaced and the Train A SCWS was returned to operable status on December 15,2007 NRC FORM 366 (9-2007)

14. SUPPLEMENTAL REPORT EXPECTED O YES (If yes, complete 15. EXPECTED SUBMISSION DATE).

0 NO SYSTEM SYSTEM COMPONENT

15. EXPECTED SUBMISSION DATE COMPONENT MANU-FA CTURER MANU-FACTURER MONTH 04 DAY 28 REPORTABLE TO EPlX

EVENT DESCRIPTION

' LICENSEE EVENT REPORT (LER)

U.S. NUCLEAR REGULATORY COMMISSION (9-2007)

CONTINUATION SHEET On October 1,2007, Nuclear Management Company, LLC (NMC) staff identified leakage under the insulation on the 121 (Train A shared between Units 1 and 2) Control Room chiller'. The leakage was attributed to a flange leak and a work order was initiated.

On December 11,2007, NMC staff determined that the leakage was not due to a flange leak, but due to a very minor (about three drops per minute) through wall leak on the associated flexible spool piece2. On December 12, 2007, NMC staff determined the 121 Control Room Chiller was inoperable as a result of the leaking flexible spool piece. Thus, the 121 Control Room Chiller and Train A Safeguards Chilled Water System (SCWS) was inoperable for more than 60 days. Technical Specification (TS) 3.7.1 1 (SCWS) Condition A requires that an inoperable SCWS loop be returned to operable status within 30 days. TS 3.7.1 1 Condition B requires that if Condition A is not met, both units must be in Mode 3 in 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and Mode 5 in 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />.

3. PAGE 2 o f 4

EVENT ANALYSIS

6. LER NUMBER YEAR SEQUENTIAL REV NUMBER NO 2007 -

05

- 0 I. FACILITY NAME Prairie Island Nuclear Generating Plant Unit 1 Since neither unit was shutdown as required by TS 3.7.1 1 Condition B, this event is being reported in accordance with 10 CFR 50.73(a)(2)(i)(B) as a condition prohibited by TS.

2. DOCKET 05000282 Impact on Safety System Functional Failure Performance Indicator No actual loss of function occurred as a result of this event. There was a short time (approximately three minutes) Train B SCWS was unpowered (while the power source for the 122 Control Room Chiller was being switched from Unit 1 to Unit 2). Unit 1 Train B (D2) emergency diesel generator3 was removed from service at 1420 CST on December 11,2007, for planned maintenance. TS does not require supported equipment (like SCWS) for an inoperable diesel generator to be declared inoperable. However, TS 3.8.1 Condition B.2 requires the associated function (in this case Train B SCWS) to be declared inoperable if the redundant function (Train A SCWS) is found to be inoperable.

This resulted in entering TS Limiting Condition for Operation (LCO) 3.0.3 as required by TS 3.7.1 1 Condition E (two SCWS loops inoperable).

Train B SCWS (which had been on its Unit 1 power supply) was transferred to its Unit 2 power supply in order to make that train operable. TS LC0 3.0.3 was exited at 0928 CST on December 12, 2007.

Since both trains of SCWS would not have been declared inoperable had D2 not been removed from service to perform maintenance, this event is not reportable per 10CFR 50.73(a)(2)(v).

Ells Component Identifier: CHU 2 Ells Component Identifier: EXJ 3 Ells Component Identifier: DG

SAFETY SIGNIFICANCE LICENSEE EVENT REPORT (LER)

U.S. NUCLEAR REGULATORY COMMlsSlON (9-2007)

CONTINUATION SHEET I

The SCWS, a shared system between the two units, circulates chilled water to provide ambient air cooling to essential areas, including the control room, Unit 1 safeguards 4160 V A C ~

and 480 V A C ~

safeguards bus rooms, residual heat removal6 (RHR) pump pits, relay room, and the event monitoring7 equipment room. The system functions during normal plant operations and accident conditions. The system function is to remove heat generated by safety related equipment and accident conditions.

1. FACILITY NAME Prairie Island Nuclear Generating Plant Unit 1 The SCWS consists of two separate, but normally cross-connected, closed 100% capacity loops.

Each loop consists of a header with water chiller, expansion tank, chilled water pump, unit coolers, piping, valves, instrumentation, and controls.

A safety injection (SI) signal closes the control room chiller outlet cross-connect air operated control valves, splitting the two headers so that each header is then supplied by the associated chilled water pump and chiller.

2. DOCKET NUMBER 05000282 Even if both loops should fail, operator actions are available in procedures to provide sufficient cooling to these rooms. The RHR pumps, 480V buses and 4kV buses can perform their functions without an immediate need for equipment heat removal and their long term OPERABILITY is handled by procedures. The control room and relay room can provide their functions for a shorter time period before replacement heat removal is required and long term operability is handled by procedures.

In this case, Train B of SCWS was without emergency diesel backup power from the time D2 was removed from service (1420 CST on December 11, 2007) to the time it was repowered from its Unit 2 source (0928 CST on December 12,2007). Train B of SCWS was unpowered (to support switching its source) from 0925 to 0928 CST on December 12,2007. Train A SCWS had a very minor leak that was initially discovered (although mischaracterized) on October 1, 2007. The leaking flexible spool piece was replaced and the Train A SCWS was returned to operable status on December 15, 2007.

Since this is a low pressure system the leak was expected to have remained very minor and heat removal capability would not have been affected. Thus, this event did not affect the health and safety of the public and the safety significance of this event is considered minimal.

6. LER NUMBER SEQUENTIAL REV YEAR NUMBER NO 2007 -

05

- 0

CAUSE

3. PAGE 3 o f 4 The cause of the flexible spool piece failure is under investigation. NMC will submit a supplement to this LER after the cause evaluation is completed.

4 5 Ells System Identifier: EB 6 Ells System Identifier: ED 7 Ells System Identifier: BP Ells System Identifier: IP

CORRECTIVE ACTION LI c E NS E E EVENT REPORT (LE R)

U.S. NUCLEAR REGULATORY COMMISSION (9-2007)

CONTINUATION SHEET The leaking flexible spool piece was replaced and the Train A SCWS was returned to operable status on December 15, 2007.

I. FACILITY NAME Prairie Island Nuclear Generating Plant Unit 1 Further Corrective Actions will be identified by the root cause evaluation. After completion of the root cause evaluation, NMC will supplement this LER.

PREVIOUS SIMILAR EVENTS

2. DOCKET NUMBER 05000282 Review of Licensee Event Reports for Unit 1 and Unit 2 since 2004 found no previous similar events where both units were operating in a condition prohibited by TS LC0 3.7.1 1.

6. LER NUMBER YEAR SEQUENTIAL REV NUMBER NO 2007 -

05

- 0

3. PAGE 4 o f 4