NRC-96-0133, Provides Response to 961105 Request for Addl Info Re 951122 License Amend & Listed Ref Info,To Extend EDG Allowed Outage Times

Provides Response to 961105 Request for Addl Info Re 951122 License Amend & Listed Ref Info,To Extend EDG Allowed Outage Times

ML20135E141
Person / Time
Site:	Fermi
Issue date:	12/04/1996
From:	Gipson D DETROIT EDISON CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
CON-NRC-96-0133, CON-NRC-96-133 NUDOCS 9612110034
Download: ML20135E141 (6)

Text

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j

• Dougtzs R. Gipson

$ -. Seruor Vee Presdent j Nuclear Generation i

Detroit re-6400 North DisHe Highway Newport, Mmhigan 48166 7 o33> s86 5249 i

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i December 4,1996 NRC-96-0133 i

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! U. S. Nuclear Regulatory Commission

! Attn: Document Control Desk 3

Washington, D. C. 20555 i

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References:

1) Fermi 2 l NRC Docket No. 50-341 i NRC License No. NPF-43 l

2) Detroit Edison Letter to NRC, " Proposed Technical l Specification Change (License Amendment)- Emergency Diesel l Generator Action Statements, Surveillance Requirements and Reports," NRC-95-0124, dated November 22,1995

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i j 3) Detroit Edison Letter to NRC," Response to Questions on Proposed Emergency Diesel Generator Technical Specification Change," NRC-96-0008, dated February 19,1996 i

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4) Detroit Edison Letter to NRC," Response to NRC Letter on

Emergency Diesel Generator Allowed Outage Time Extension j (TAC No, M94171)," NRC-96-0041, dated April 19,1996 i

i 5) Detroit Edison Letter to NRC," Response to Probabilistic Safety i Assessment Questions Related to Request for Increasing Emergency Diesel Generator Allowed Out of Service Time i (TAC No. M94171)," NRC-96-0050, dated May 3,1996

Q NRC Letter to Detroit Edison," Request for Additional i 6)

] Information Related to the Amendment to Extend Emergency 'g i Diesel Generator Allowed Outage Times at Fermi 2 (TAC No.

! M94171)," dated November 5,1996

! 090127 9612110034 961204 i PDR ADOCK 05000341 p PDR ri

1 USNRC NRC-96-0133

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Subject:

Additional Information Related to the License Amendment to Extend Emergency Diesel Gmerator Allowed Outage Times at Fermi 2 On November 22,1995, Detroit Edison submitted the Reference 2 License j Amendment request to extend the allowed outage times for the emergency diesel  !

generators. Supplemental information related to the amendment request was j submitted to the NRC in References 3,4, and 5. The Reference 6 NRC letter  !

subsequently requested additional information related to the risk matrix described in the Reference 5 Detroit Edison letter. This letter provides responses to the four items requested as described in the Reference 6 letter enclosure. l Item 1 Reauest Provide a general description of the risk matrix, focusing on capabilities and limitations.

Response

I The on-line maintenance risk matrix, created as part of the Fermi 2 Maintenance Rule implementation, is developed each year from a list of scheduled system outages for that year. In the current version of the matrix, the first series of columns in the matrix contains descriptive information that characterizes each system outage. These outages are chronologically arranged as they are scheduled to occur during the year.

Information including the scheduled start date, scheduled end date, outage duration, system description and the applicable division plus an indication of the risk significance of the outage is provided for each system outage in the first few columns of the matrix. Subsequent columns consist of risk indicators for other systems or sub-systems that may require contingency maintenance during a scheduled system outage.

These risk indicators are defined as " Low,"" Moderate," "High," and " Unacceptable" based on the EPRI PS A Applications Guide criteria used for characterizing temporary risk increases. The response to Item 3 further describes how plant-specific risk indicators are derived from the Fermi 2 PSA for specific scenarios, and the response to Item 4 describes how this information is used to support decision-making.

The matrix is conservative in that partial unavailability is not considered as an option.

Either all components are available or the system /sub-system is unavailable. A prime example of this is the General Service Water System (GSW). During half of the year only three GSW pumps are required to satisfy system heat load requirements. This would normally leave two GSW pumps in standby. Rather than being in standby, if one of the non-operating pumps were placed in corrective maintenance, then the matrix would assume that GSW would not be available during the corrective maintenance. For an extreme case like this, Work Control may request a special evaluation to be performed by the PS A group if a system outage were scheduled concurre.nt with the GSW corrective maintenance.

d USNRC

- NRC-96-0133 l .

Pa;,e 3 A limitation of the matrix is the fact that surveillance tests that may make a system inoperable are not included. The actual duration of such surveillances are usually short and thus have only a minor impact on risk. Another limitation is that no more than two systems or sub-systems concurrently unavailable can be evaluated with the matrix. A special evaluation could be performed for more complicated situations.

Item 2 Heauest Provide a list of systems that are modeled in the risk matrix.

Response 2 A table with the system ids and a system description for those systems included in the Fermi 2 risk matrix follows:

System ID System Description Al NIAS Division 1 '

A2 NIAS Division 2 B1 BOP AC division 1 buses B2 BOP AC division 2 buses B4 4160V bus 64B and EDG bus 11EA BI Standby Liquid Control System Cl EECW/EESW division 1 C2 EECW/EESW division 2 C4 4160V bus 64C and EDG bus 12EB CA Core Spray System division 1 CB Core Spray System division 2 CC RBCCW CD Control Rod Drive Hydraulic System CF 480V MCC 72CF CN Condensate and Heater Feed Pumps CT Condensate Storage and Transfer System DA Division 1 DC power DB Division 2 DC power DC BOP DC power DW High Drywell Pressure Signal E5 4160V bus 65E and EDG bus 13EC F5 4160V bus 65F and EDG bus 14ED FL Feedwater Control Logic FW Feedwater System l G1 Emergency Diesel EDG 11 G2 Emergency Diesel EDG 12 l

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l System ID System Description (Continued)

G3 Emergency Diesel EDG 13 G4 Emergency Diesel EDG 14  ;

GT Combustion Turbine Generator (CTG 11-1)

HA RHRSW division 1 HB RHRSW division 2 HP High Pressure Coolant Injection System (HPCI) )

IS Containment Isolation System LA RHR division 1 j LB RHR division 2 l LV Low RPV Water Level Signal MC Main Condenser MS MSIVs 4 NI Nitrogen Supply System i NP Low Pressure Irjection Permissive Signal PT Reactor Recirculation Pump Trip RC Reactor Core Isolation Cooling System (RCIC) l RS Reactor Protection System /CRD Control System j SA Station Air i SF Standby Feedwater System SR SRVs SW General Service Water Tl RHR Complex Cooling Towers - Division 1 T2 RHR Complex Cooling Towers - Division 2  ;

TB TBCCW l l

VT Hardened Vent Path Item 3 Reauest Provide a description on how risk information from your PRA is incorporated into the risk matrix.

I Resomse 3 A separate RISKMAN PSA evaluation is made for each scheduled system outage using the following relationship for dual outage configurations:

CDP = RAW x [ scheduled duration] x CDF I Risk achievement worths (RAW) are first computed for each of the other systems included in the PS A model given the scheduled system outage plant configuration.

The RAWS are multiplied by the system outage plant configuration core damage frequency (CDF). Consistent with the EPRI PSA Applications Guide,if this value is 4

USNRC NRC-96-0133

. Page 5 greater than 0.001 then the configuration falls into the unacceptable risk category (category X). If the configuration is not a category X condition then the core damage probability (CDP) is computed. 'Ihe CDP for the dual configuration of scheduled ,

system outage plus contingency system outage is obtained by multiplying the previous result by the duration (m years) of the system outage. The configuration is then categorized according to the following scheme, consistent with the EPRI PS A Applications Guide:

I e L- Low Risk, CDP for the event is less than 1.0E-06

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• M- Moderate Risk, CDP between 1.0E-05 and 1.0E-06

• H- High Risk, CDP greater than 1.0E-05 i

I Item 4 Reauest Provide a brief description of your procedure (s) to implement the use of the risk matrix.

Response 4 The primary procedures used for controlling the work control process at Fermi 2 are MWC02," Work Control," and MWC03," Surveillance / Performance Package Control." In conjunction with these governing procedures, Fermi 2 has implemented the Work Control Daily Scheduling Program whose goal is to maintain safe and efficient electrical generation capacity by effectively planning and scheduling surveillances, performances (PSTs), preventive maintenance, corrective maintenance, and other activities. The program is presently defined by the Daily Scheduling Program Guidelines document (Program Guidelines). The Program Guidelines describe the System Outage Risk Matrix (risk matrix) as a means of evaluating the risk associated with scheduling work during the operating cycle to avoid undue risk resulting from performing the work.

The Program Guidelines provide the following guidance for the use of the risk matrix in reviewing pre-scheduled and emergent work activities:

• The schedule should be reviewed using the System Outage Risk Matrix to determine if any planned system outage work results in a risk designation above

" Low"(as defm' ed in Response 1 above).

• Work that results in " Moderate" risk should be evaluated to determine if the configuration must be entered. If rescheduling cannot downgrade the risk to

" Low," plant management will be informed and contingency actions considered prior to the start of the system outage work.

• Work that results in "High" risk will be rescheduled or brought to the attention of Work Control and Operations management for approval.

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• Work with " Unacceptable" risk will be rescheduled (entry into this configuration

, is prohibited).

• Emergent work is evaluated with the risk matrix to determine the impact of performing the new work in conjunction with the originally scheduled work. If the emergent work is urgent, previously planned work may be rescheduled based on risk impact. Emergent work requiring scheduling or preplanned work i requiring rescheduling within the preapproved frozen schedule will be.

documented and approved as prescribed in the Program Guidelines.

If you have questions regarding this response, please contact Mr. Robert Newkirk at (313) 586-4211.

i Sincerely,

! /_97 i

cc: A. B. Beach M. J. Jordan

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A. J. Kugler

A. Vegel i

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