05000275/FIN-2010005-03

Finding

Title

Corrosion of Containment Fan Cooler Unit Cooling Coil Casings

Description

The inspectors identified an unresolved item concerning the degradation of the containment fan cooler unit cooling coil casings due to corrosion. Specifically, the issue concerns the licensees actions to verify the heat removal capability of the containment fan coolers under degraded conditions and the failure to take corrective actions for the repair or replacement of the corroded cooling coil assemblies.

The containment fan cooler units function during normal plant operation to maintain the containment atmosphere at design conditions. During accident conditions, the cooler units automatically initiate to maintain containment operability. Diablo Canyon Units 1 and 2 each have five cooler units installed inside the containment building. Each cooler unit has two cooling coil banks with six coils stacked in each bank. Each of the coils is mounted on sheet metal casings and the casings are mounted within the cooler unit frame. The casings act to prevent air bypass between the coils in the banks and as structural support for the coil tubes and fins.

The inspectors reviewed Diablo Canyon Power Plant Health Issue Reports 2002-S023-002 and 2002-S023-003 which identified corrosion of the containment fan cooler unit cooling coil casings. The power plant health issue reports acknowledged that continued casing corrosion would decrease the available design margin of the heat removal capacity of the cooler unit cooling coils. Containment Fan Cooler Unit Coil Study, Phase 1, Revision 0, recommended that the corroded coil casing be repaired or replaced whenever possible to avoid impacting the cooler unit heat removal capacity. The licensees initial recommended corrective action, as described in the power plant health issue reports, was to replace the cooling coil assemblies in Units 1 and 2 beginning in Refueling Outage 1R13 (Fall 2005). The replacement plans were not implemented and the licensee currently plans to begin replacement of the cooling coil assemblies during upcoming Refueling Outages 1R18 and 2R18. All cooling coil assemblies in Units 1 and 2 are scheduled to be replaced by Refueling Outage 1R20 and 2R20, respectively.

The inspectors determined that additional information was needed to resolve this issue. The inspectors were unable to clearly determine the design basis function of the cooling coil casings based upon documentation provided by the licensee during the inspection. Additionally, the licensee has not quantified the effect of the corrosion to verify that the cooling coil casing functions would be maintained under the current degraded conditions and has not provided a technical justification for the acceptability of the proposed coil assembly replacement schedule. The licensee has agreed to provide this information for NRCs review.

Because more information is necessary to resolve this issue, it is considered an unresolved item pending further NRCs review. The NRC will review the licensees evaluation to determine

If the licensees failure to verify the heat removal capability of the containment fan cooler units is a performance deficiency

If the licensees decision to delay taking corrective actions for repair or replacement of the corroded cooling coils constitutes a violation of NRC requirements

The licensee entered this issue into its corrective action program as Notification 50364991. This unresolved item is identified as URI 05000275; 323/2010005-03, Corrosion of Containment Fan Cooler Unit Cooling Coil Casings.

03
Site:	Diablo Canyon
Report	IR 05000275/2010005 Section 1R07
Date counted	Dec 31, 2010 (2010Q4)
Type:	URI:
cornerstone	Mitigating Systems
Identified by:	NRC identified
Inspection Procedure:	IP 71111.07
Inspectors (proximate)	E Wong P Goldberg L Ricketson M Brown M Peck C Graves R Kopriva D Allen C Osterholtz I Anchondo D Reinert C Alldredge B Lattad Reinertj Braisted C Denissen P Goldberg M Peck G Miller
INPO aspect
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v • d • e

Finding - Diablo Canyon - IR 05000275/2010005

1(0)2(6)3(4)4(5)5(12)6(5)7(11)8(0)201(7)301(0)402(2)403(2)501(0)

IR 05000275/2010005: 1 2 3 4 5 6 7 8 9 10 11 12

Finding List (Diablo Canyon) @ 2010Q4

CCA Matrix: 2010Q4

	Q	CCA	Title
05000275/FIN-2010402-02	2010Q1		Security
05000323/FIN-2009009-01	2010Q1	P.2	Failure to Follow Design and Configuration Control Requirements
05000323/FIN-2009009-02	2010Q1	P.2 P.1(a)	Failure to Conduct an Adequate Post-Modification Test
05000323/FIN-2009009-03	2010Q1	P.2	Failure to Evaluate a Change to the Facility as Described in the Final Safety Analysis Report Update Associated with the Addition of Manual Actions in the Safety Analysis
05000275/FIN-2010002-02	2010Q1	P.2	Failure to Update the Final Safety Analysis Report with the Current Plant Design Bases
05000275/FIN-2010002-03	2010Q1		Failure to Report a Condition That Could Have Prevented the Fulfillment of a Safety Function
05000275/FIN-2010002-05	2010Q1	P.2	Failure to Submit a LERE for a Common-Cause Inoperability of Independent Trains or Channels
05000275/FIN-2010002-04	2010Q1	P.2	Less Than Adequate Evaluation Following a Failure of Both Motor Driven Auxiliary Feedwater Trains
05000275/FIN-2010402-01	2010Q1		Security
05000275/FIN-2010002-01	2010Q1	P.3	Failure to Effectively Implement the Seismically-Induced Systems Interaction Program
05000275/FIN-2010003-02	2010Q2		Inadequate Corrective Actions Following Identification of a Nonconservative Technical Specification
05000275/FIN-2010007-03	2010Q2	H.14	Non-Conservative Decision Making resulted in a Violation of Technical Specification
05000275/FIN-2010003-01	2010Q2	P.2	Failure to Perform Unit 1 Containment Concrete Inspections
05000275/FIN-2010007-05	2010Q2	P.2	Inadequate Operability Determination Associated With the Offsite Degraded Voltage Protection Scheme
05000275/FIN-2010007-06	2010Q2		Second Level Undervoltage Relay Time Delay to Initiate Load Shed and Sequencing Upon the Diesel Generator is Adequate to Assure Plant Safety
05000275/FIN-2010007-08	2010Q2	P.2	Inadequate Drawings and Procedures to Align Emergency Makeup Water Supply from Diablo Canyon Creek to Support the Auxiliary Feedwater System
05000275/FIN-2010007-07	2010Q2		Nonconservative Inputs into Motor Operated Valve Calculation
05000275/FIN-2010007-10	2010Q2		Failure to Update Text to Reflect Credited Design Class I Makeup Flowpath to Component Cooling Water Expansion Tank in the Final Safety Analysis Report Update
05000275/FIN-2010007-09	2010Q2		Failure to Update Feedwater Rupture Accident Analysis in the Final Safety Analysis Report Update
05000275/FIN-2010007-04	2010Q2	P.2	Failure to Update the Final Safety Analysis Report Update with the Current Plant Design Bases Section
05000275/FIN-2010007-02	2010Q2	P.2	Failure to Adequately Evaluate Changes to the Diesel Testing as Described in the Final Safety Analysis Report Update
05000275/FIN-2010007-01	2010Q2	H.14	Less than Adequate Change Evaluation to the Facility as Described in the Final Safety Analysis Report Update
05000275/FIN-2010003-03	2010Q2	P.2	Failure to Report a Condition that Could Have Prevented the Fulfillment of a Safety Function
05000275/FIN-2010201-02	2010Q3	H.12	Security
05000275/FIN-2010004-05	2010Q3		Inadequate Design Control for the Auxiliary Saltwater System
05000275/FIN-2010004-04	2010Q3	P.2	Inadequate Operability Determination
05000275/FIN-2010004-03	2010Q3	H.8	Inadequate Risk Assessment during Planned Maintenance Activities
05000275/FIN-2010004-02	2010Q3	P.3	Inadequate Risk Management during a Planned Auxiliary Saltwater Pump Outage
05000275/FIN-2010004-01	2010Q3	P.1	Failure to Identify a Degraded Fire Barrier
05000275/FIN-2010201-06	2010Q3		Security
05000275/FIN-2010201-01	2010Q3	H.14	Security
05000275/FIN-2010201-03	2010Q3	P.6	Security
05000275/FIN-2010006-03	2010Q3	P.2	Failure to Submit Complete and Accurate Information for a Requested License Amendment
05000275/FIN-2010006-01	2010Q3	H.14	Inadequate Design Control for the Emergency Diesel Generator
05000275/FIN-2010006-02	2010Q3	H.14	Failure to Maintain Proficiency of Operators to Meet the Time Critical Operator Actions
05000275/FIN-2010006-04	2010Q3	H.14	Untimely and Inadequate Corrective Actions for the Emergency Diesel Generators
05000275/FIN-2010006-05	2010Q3	P.2	Failure to Appropriately Evaluate Failed Residual Heat Removal Surveillance Test
05000275/FIN-2010201-04	2010Q3		Security
05000275/FIN-2010403-01	2010Q3	P.1	Security
05000275/FIN-2010403-02	2010Q3		Security
05000275/FIN-2010201-05	2010Q3		Security
05000275/FIN-2010201-07	2010Q3		Security
05000275/FIN-2010005-07	2010Q4	P.6 P.3(c)	Inadequate Quality Verification Audits
05000275/FIN-2010005-03	2010Q4		Corrosion of Containment Fan Cooler Unit Cooling Coil Casings
05000275/FIN-2010005-01	2010Q4	P.3	Failure to Maintain a Fire Barrier
05000275/FIN-2010005-02	2010Q4	H.7	Inadequate Transient Combustibles Procedure
05000275/FIN-2010005-04	2010Q4	H.14	Inadequate Operability Determinations
05000275/FIN-2010005-05	2010Q4	H.7	Less than Adequate Containment Recirculation Sump Design Control
05000275/FIN-2010005-06	2010Q4	P.2	Inadequate Emergency Diesel Generator Surveillance Testing

Self-Identified List (Diablo Canyon)

	Q	Title
05000275/FIN-2010002-06	2010Q1	Licensee-Identified Violation
05000275/FIN-2010007-11	2010Q2	Licensee-Identified Violation
05000275/FIN-2010003-04	2010Q2	Licensee-Identified Violation
05000275/FIN-2010005-08	2010Q4	Licensee-Identified Violation
05000275/FIN-2010005-09	2010Q4	Licensee-Identified Violation
05000275/FIN-2010005-10	2010Q4	Licensee-Identified Violation
05000275/FIN-2010005-11	2010Q4	Licensee-Identified Violation
05000275/FIN-2010005-12	2010Q4	Licensee-Identified Violation

[Diablo Canyon Findings full list]

05000275/FIN-2010005-03

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