ML13170A130

Public Slide - NFPA 805 Transient Combustible Controls

ML13170A130
Person / Time
Site:	Summer
Issue date:	06/18/2013
From:	South Carolina Electric & Gas Co
To:	Ellen Brown Plant Licensing Branch II
Brown E NRR/DORL/LPL2-1
References
TAC ME7586
Download: ML13170A130 (18)

Text

NFPA 805 Transient Combustible Controls V. C. Summer Nuclear Tom Keckeisen, Operations

-Fire Protection

PURPOSE Provide an Overview of the Executive Summary Describe the Process for the Control of Transient Combustibles and Ignition Sources Specifically address Controls in Areas with Performance

-Based Fire Modeling

Objective Goal is to maintain a program consistent with NFPA 805 requirements and its supporting documentation and calculations NFPA 805 Section 3.3.1.2, Control of Combustible Materials NFPA 805 Section 3.3.1.3, Control of Ignition Sources VCSNS Transient Controls Controls to be based on risk by assigning combustible control levels based on the Fire PRA and performance based insights.

Developing an Engineering calculation to define fire zone PRA CDF sensitivity to transients.

Controls levels defined by consensus between Fire Protection and PRA engineers.

Industry is developing a white paper on the general transient combustible/ignition source process.

Assignment of Control Levels Level of controls will range from Low (Level 4) to High (Level 1)

Level 4: Fire Zones with low risk contribution. Fire PRA assumes full compartment burn and zones are not sensitive to higher transient influence factors

(~130 Fire Zones)

Level 3: Level 4 Fire Zones (low risk) which contain specific areas with deterministic fire barriers and /or separation features (i.e. ERFBS or 20 ft separation) (~15 Fire Zones)

Assignment of Control Levels Level 2: Fire Zones with higher risk contribution or zones which are sensitive to higher transient factors . Primarily AC/DC distribution and electrical cable chases (~30 Fire Zones).

Level 1: Fire Zones governed by Performance

-Based Fire Modeling or zones where failure to follow transient controls are impacting (6 Fire Zones).

Risk Insights from the Fire PRA Full Compartment Burn

-Low Risk Contribution

-No credit for any fire protection feature

-Assigned as Level IV

-Several exceptions to this general assignment of this level

Risk Insights from the Fire PRA Fire Size and Location

- Peak Heat Release Rate (HRR)

- 317kW - If Quantity / Type can cause a Peak HRR > 317kW. May not be analyzed in Fire PRA.

- Scenarios governed by limiting fire size to 317kW need to be controlled

Risk Insights from the Fire PRA Transient Influence Factors

- Weighting Factors for Transient Ignition Frequencies

- Maintenance / Occupancy / Storage (1-Low, 3-Medium, 10

-High) - Sensitivity Calculation: All factors increased to 10

-High - Fire Zones with Significant Impact (CDF increase >1E

-06) are more sensitive to increases in Transient Influence Factors

- Assigned as Level II

Risk Insights from the Fire PRA Probability of Failing to Follow Controls

-Fire PRA analyzed two (2) of the Risk Significant Zones assuming a probability of failing to follow combustible controls

-Risk Significant Zones with Low Transient Influence Factors

-Assigned as Level I

Risk Insights from the Fire PRA Fire Scenarios with Structural Steel

-Structural Steel Bounding Analysis: Potential fire scenarios involving structural collapse due to thermal damage -3 Fire Zones meet criteria: Unprotected steel / high in

-situ fire source.

- No transient combustible impact

-Low Risk Other NFPA 805 Elements Spatial Separation (20 ft.) per NFPA 805, 4.2.3.3 (a)

Electrical Raceway Fire Barrier Systems (ERFBS) per 4.2.2.2 (c)

Fire Protection Equivalency Evaluations (FPEEE) - "Adequate for the Hazard"

VCS Performance Based Fire Modeling NFPA 805 4.2.4.1 permits the use of fire modeling for addressing variances from deterministic requirements (VFDR's)

Applied to Four (4) Fire Areas which have cable tray targets close to the floor Fire model specifies administrative controls to be designed and implemented so that fire damage to the targets within the fire zone is prevented.

VCS Performance Based Fire Modeling The Four (4) Fire Areas where Performance Based Fire Modeling was used will be considered Level I Areas and have the highest level of control.

These areas will be treated as "restricted" areas (i.e. no transient combustibles allowed without FP approval and elevated compensatory actions)

VCS Transient Controls Level 4: General Housekeeping Controls Apply Level 3: General Housekeeping Controls Apply with additional controls for areas with deterministic requirements.

Level 2: Designated by Fire PRA as Risk Significant. Controls on quantities, duration, Class B combustibles.

Level 1: Restricted Area

- No Transient Combustibles Allowed without additional evaluation / approval required to ensure fire damage is prevented as documented in fire model.

Implementation Transient Combustible Control Procedure Plant Housekeeping / Staging / Storage Procedure Maintenance Work Area Procedure /

Instruction Fire Prevention Inspection Procedures Plant Area Designation / Physical Controls

Summary Goal is to maintain a program consistent with NFPA 805 requirements and its supporting documentation and calculations Provides a Risk Approach to the control of Transient Combustibles and Ignition Sources Allows for a more focused controls, inspections, observations in higher risk areas.

Provides site specific information to support additional risk considerations

Questions or Comments