ML11186A904
| ML11186A904 | |
| Person / Time | |
|---|---|
| Site: | Perry, Summer, Crystal River, Ginna, Crane  |
| Issue date: | 06/30/2011 |
| From: | Thompson B South Carolina Electric & Gas Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 46997 | |
| Download: ML11186A904 (7) | |
Text
10 CFR PART 21 REPORT DISTRIBUTION:
Document Control Desk O-Pl-17 DOCUMENT CONTROL DESK: Please ensure that this document is entered into ADAMS.
0613012011 U.S. Nuclear Regulatory Commission Operations Center Event Report PagelI Power Reactor Event#
46997 Site: SUMMER Notification Date / Time: 06/29/2011 09:49 (EDT)
Unit: 1 Region: 2 State: SC Event Date lTime: 06/27/2011 16:11 (EDT)
Reactor Type: [1] W-3-LP Last Modification: 06/30/2011 Containment Type: DRY AMB NRC Notified by: BRUCE THOMPSON Notifications: MARK FRANKE R2DO HQ Ops Officer: STEVE SANDIN PART 21 GP (email)
NRR Emergency Class: NON EMERGENCY 10 CFR Section:
21.21 UNSPECIFIED PARAGRAPH Unit Scram Code RX Crit Init Power Initial RX Mode Curr Power Current RX Mode 1
N Yes 100 Power Operation 100 Power Operation APPENDIX R ANALYSES FAILS TO RECOGNIZE HOT-SHORT FAILURE RESULTING IN THE LOSS OF AN ESSENTIAL ELECTRICAL BUS The following Part 21 report was received via fax:
"10 CFR 21: Appendix R analyses conducted for Virgil C. Summer Nuclear Station (VCSNS) failed to identify that a fire-induced hot-short failure in an ammeter circuit would result in a loss of the B-train 7.2KV essential electrical bus (XSW1 DB).
"Appendix R analyses performed by Gilbert/Commonwealth (now Worley Parsons) in the early 1980s failed to recognize the possibility of a fire-induced hot-short condition in a circuit that was identified as being required for safe shutdown. This circuit connects a set of sensing current transformers (CTs) to an ammeter on the Main Control Board, and provides over-current sensing for an over-current relay. GilbertlCommonwealth recognized that a fire-induced open circuit in this ammeter circuit would result in damage to, or a fire in, the B-train 7.2kV essential switchgear. Thyrite protectors were added to the circuit to protect the CTs from this open circuit condition as part of the Appendix R analysis.
"However, this analysis and resolution failed to consider the hot-short-to-ground failure mode. Current from a hot-short could flow through the ammeters, or neutral conductor, and then through the bus neutral over-current relay to ground. This could actuate the over-current relay, which in turn would actuate a lock-out relay and trip all incoming breakers to bus XSW1 DB. This bus provides credited B-train power to safe-shutdown components credited for this scenario. The Appendix R analyses conducted for VCSNS by Gilbert/Commonwealth did not address the hot-short scenario and is considered to be a defect, or omission. reportable under 10 CFR 21.
"This condition was identified during the circuit analysis review for transitioning the Appendix R Fire Protection
0613012011 U.S. Nuclear Regulatory Commission Operations Center Event Report Page Power Reactor Event#
46997 Program to NFPA 805 and was reported to the NRC as an unanalyzed condition on 05/03/2011 (see Event Notification 46811). Corrective actions have been taken to address this issue."
The licensee informed the NRC Resident Inspector.
UPDATE FROM JOE MARSDEN TO MARK ABRAMOVITZ ON 6/30/2011 AT 1643 ***
"Worley Parsons Investigation Results:
"Although this design was not a generic or standard design, Worley Parsons performed further evaluation, including extent of condition, for other Nuclear Power Plants that Worley Parsons performed the original design and performed Appendix R Compliance Review/Modifications.
Five plants were identified as follows:
"1) Crystal River 3: Worley Parsons discussed the issue with Progress Energy and jointly concluded that Crystal River 3 is not impacted because their corresponding current transformer circuit design has a different configuration. The circuit design is not generic or programmatic.
"2) TMI Unit 1: TMI is not impacted because their corresponding current transformer circuit design has a different configuration. The circuit design is not generic or programmatic.
"3) Perry: The Appendix R Compliance Review was accomplished by a team of Worley Parsons and others. Since Worley Parsons was involved with the Appendix R analysis and the affected electrical drawings are not readily available at Worley Parsons, it was concluded that Worley Parsons could not complete the evaluation to determine if the Perry design condition could cause a substantial safety hazard. Worley Parsons issued letter PNPP-O-CO-01 1-WCLT-0001 to the Perry Design Engineering Manager, recommending Perry to complete the evaluation pursuant to 10CFR21.21(a).
"4) V.C. Summer: V.C. Summer is the subject plant and is impacted. VC. Summer is Issuing LER #2011-001-00, which constitutes the Part 21 Notification for this design defect, or omission.
"5) R.E. Ginna: Worley Parsons did not perform the Appendix R analysis for Ginna.
"Corrective Action:
"V.C. Summer has implemented immediate compensatory measures for this condition until a permanent solution is Identified. A root cause analysis was jointly performed with V.C. Summer. The root cause analysis and Worley Parsons corrective action program review considered this an isolated incident due to human error. No programmatic/procedure corrective actions were identified due to the historical nature of the issue.
"Actions to preclude recurrence: Human performance issues from this event will be communicated to the Worley Parsons Nuclear Engineering staff under our corrective action and lessons learned program."
Notified R1DO (Welling), R2DO (Franke), and R3DO (Lipa). Notified the Part 21 Group via e-mail.
WorleyParsons resources & energy DATE June 30, 2011 2675 Morgantown Road Reading, PA 19607 Telephone: +1 610 855 2000 Facsimile:
+1 610 855 2001 www.worleyparsons.com PROJ NO FAX NO 1-301-816-5151 PAGES 4 including cover page TO NRC Documents Control Desk COMPANY FROM Raffi Shahabian SUBJECT 10CFR21 NOTIFICATION OF DESIGN ERROR IN CURRENT TRANSFORMER CIRCUIT Attached is a letter to the NRC Document Control desk with one attachment.
If there are any questions, please call 610-855-2372.
c:\\suzanne's files\\1 suzanne's stuffitemplates\\fax (reading).doc:
Transmission Ref EcoNomicý
2675 Morgantown Road W orleyParsons Reading, PA 19607 Telephone: +1 810 855 2000 resources & energy Facsimile: +t 610 855 2001 www.worleyparsons.com Date: 30 June 2011 Ref: Letter# PRE-N-169 Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001
SUBJECT:
IOCFR21 NOTIFICATION OF DESIGN DEFECT IN CURRENT TRANSFORMER (CT) CIRCUIT Description of the Defect:
An Appendix R modification for Virgil C. Summer Nuclear Station (VCSNS) performed in the mid 1980s, made to a CT circuit to bring it into compliance with Appendix R safe shutdown requirements, is not adequate. The modification does not address the spurious lock-out of an essential bus, XSW1 DB, due to a postulated fire-induced hot short to the current transformer circuit.
Date of Identification V.C. Summer identified to WorleyParsons on June 29, 2011, that they concluded this issue was considered a defect or omission, and they also notified the NRC via Event Notification 46997.
Backaround:
An Appendix R analysis performed by Gilbert/Commonwealth (now WorleyParsons) in the early 1980s failed to recognize the possibility of a fire-induced hot-short condition in a circuit that was identified as being required for safe shutdown. This circuit connects a set of sensing current transformers to ammeters on the Main Control Board, and also provides over-current sensing for an over-current relay, Gilbert/Commonwealth recognized that a fire-induced open circuit in this ammeter circuit would result in damage to, or a fire in, the B-train 7.2kV essential switchgear.
Thyrite protectors were added to the circuit to protect equipment from this open circuit condition as part of the Appendix R analysis.
However, this analysis and resolution failed to consider the fire-induced hot-short failure mode.
Current from a hot-short could flow through the ammeters, or neutral conductor, and then through the bus neutral over-current relay to ground. This could actuate the over-current relay, which in turn, would actuate a lock-out relay and trip all incoming breakers to bus XSW1 DB. This bus provides power to B-train safe-shutdown components credited for this scenario.
This condition was identified during the V.C. Summer circuit analysis review for transitloning the Appendix R Fire Protection Program to NFPA 805. This was reported by V.C. Summer to the NRC as an unanalyzed condition on 05/03/2011 (see Event Notification 46811).
V.C. Summer concluded their 10CFR21 evaluation and reported on Event Notification 46997.
WorleyParsons conducted a 10CFR21 possible reportability evaluation, including extent of condition, under our procedure, and the results are provided below.
Page 1 of 2 EcoNomic
WorleyParsons resources & energy WorleyParsons Investiqation Results:
Although this design was not a generic or standard design, WorleyParsons performed further evaluation, including extent of condition, for other Nuclear Power Plants that WorleyParsons performed the original design and performed Appendix R Compliance Review/Modifications.
Five plants were identified as follows:
- 1) Crystal River 3: WorleyParsons discussed the Issue with Progress Energy and jointly concluded that Crystal River 3 is not impacted because their corresponding current transformer circuit design has a different configuration. The circuit design is not generic or programmatic.
- 2) TMI Unit 1: TMI is not impacted because their corresponding current transformer circuit design has a different configuration. The circuit design is not generic or programmatic.
- 3)
Perry: The Appendix R Compliance Review was accomplished by a team of WorleyParsons and others. Since WorleyParsons was involved with the Appendix R analysis and the affected electrical drawings are not readily available at WorleyParsons, It was concluded that WorleyParsons could not complete the evaluation to determine if the Perry design condition could cause a substantial safety hazard. WorleyParsons issued letter PNPP-0-CO-01 1-WCLT-0001 (attached) to the Perry Design Engineering Manager, recommending Perry to complete the evaluation pursuant to 1CFR21.21 (a).
- 4) V.C. Summer: V.C. Summer is the subject plant and is impacted. V.C. Summer is Issuing LER #2011-001-00, which constitutes the Part 21 Notification for this design defect, or omission.
- 5) R.E. Ginna: WorleyParsons did not perform the Appendix R analysis for Ginna.
Corrective Action:
V.C. Summer has implemented immediate compensatory measures for this condition until a permanent solution is Identified. A root cause analysis was jointly performed with V.C. Summer. The root cause analysis and WorleyParsons corrective action program review considered this an isolated incident due to human error. No programmatic/procedure corrective actions were identified due to the historical nature of the issue.
Actions to preclude recurrence. Human performance issues from this event will be communicated to the WorleyParsons Nuclear Engineering staff under our corrective action and lessons learned program.
Person responsible for corrective action implementation, John Grove, Manager of Nuclear Engineering.
Time to complete the action July 29, 2011.
WorleyParsons contact for additional information:
Raffi Shahabian, Director of Nuclear Projects, at 610-855-2372 or email, Raffi.Shahabian@worleyparsons.com Respectfully, Mark S. Campagna Vice President General Manager, USAC Nuclear WorleyParsons
Attachment:
PNPP-0-CO-011 -WCLT-0001 Page 2 of 2 EcoNomic
WorleyParsons resources & energy Reading, PA 19607 USA Telephone 41610 855.2000 Facsmile
+1 810 855 2001 www.worleyparsons.cofl June 27, 2011 pNPP-0-C0-011 -WCLT-0001 File: PRE-169 Mr. Ted Hilston, Design Engineering Manager Perry Nuclear Power Plant 10 Center Road (A-PY-A1 60)
Perry, Ohio 44081 Re:
Perry Nuclear Station IOCFR21 Screening for Reportability Appe*ndix R Fire-Induced Fault
Dear Mr. Hilston:
ln accordance with 10CFR21.21(b), we ore informing you of ourong.ding evaluatln of a potentially reportable event for another nuclear plant, pertparagraphs (a)(1)or (a)(2) and ourNQclear Possible Reportable Event procedure, asa design defect (errot, omlssion, or other circumstance) in a safety related component for Appendix R compliance, Although Gilbert Associates Inc. (now WorleyParsots) had previous involvement with the design of Perry, our or.ganization presently does not have the full knowledge of, nor access to, the Porty Nuolsar Plant safety functions arnd Appendix R commitments to determine whether a similar design condition exists and if It couid cause m substantial safety hazaird.
Therefore, we are informing you of the design conditions so that you may evaluate the applicability at the Perry Nuclear Plant pursuant to I0CFR21.2.1(a).
A summary description of the subject Append ix R compliance issue foilows:
The specific Appendix issupe involvo'- s CT oiftqit.that odiginate.s from: a B Train 7KV power bus
.XSW{OB, t hat is credited for a ControqlRoom ceble Spreading Room fire. Bus )(WIDB feeds tWO 8 Train 480V Load Centers XSWiDBI -and XSWI DB2 {that tre.lso credited. The CT Cirouit routeAs to ammeters in the Majn Control Room. This-CT circuit also Jncludes a XSWl UB bus neutral overcurrent relay. Inthe event of a Control Room fire, a fire-in4uced hot.short to oneof the CT circuit conductors is postulated. Currentfrom the :hot sort could flow In. he CT ircult an.d posslily energlze the prot.ec*ive relay. This in-turn would energize a lokoUtrelay thatt. ptU All incoMing breakets to the credited.Train XSWI.B 7KV bus, such that credited B Train power would not be available.
if you have any questtiOns or' otmomtts, please c.ntac(Mafk aprnpogna, VP GMW at (.60) 855-3076 or Allen Hartman, Chief Electrica/l&C Engineer, at (610) 85.-2141.
Very truoy yours,
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