ML18087A409
| ML18087A409 | |
| Person / Time | |
|---|---|
| Issue date: | 05/02/2018 |
| From: | Michelle Kichline NRC/NRR/DRA/APHB |
| To: | |
| Kichline M | |
| Shared Package | |
| ML18087A347, ML17089A411 | List: |
| References | |
| CN 18-010, DC 17-006 | |
| Download: ML18087A409 (9) | |
Text
NRC INSPECTION MANUAL APHB INSPECTION MANUAL CHAPTER 0609 APPENDIX F ATTACHMENT 5 CHARACTERIZING FIRE IGNITION SOURCES
FIXED AND TRANSIENT IGNITION SOURCE FIRES Heat Release Rate Profile of Fixed Ignition Sources The Heat Release Rate (HRR) profile of fixed ignition sources consists of three stages as shown in Figure A5.1:
First Stage: t-squared growth stage during which the HRR increases from 0 kW at ignition (t = 0 seconds) to the peak HRR (HRRpeak) at t = tpeak seconds. The HRR as a function of time during this stage is given by t 2 HRR(t) = HRR peak ( ) for 0 t t peak [5-1]
t max Second Stage: HRR remains equal to HRRpeak for a period of tsteady seconds.
Third Stage: Linear decay from HRR = HRRpeak to HRR = 0 kW in tdecay seconds.
Heat Release Rate (kW) tsteady tdecay HRRpeak tpeak Time (min)
Figure A5.1 - HRR Profile for Fixed and Transient Ignition Sources Table A5.1 gives the HRR profile parameters for fixed ignition sources assumed in the Phase 2 based on NUREG-2178, Vol. 1. The HRRpeak values for electrical enclosures are the 98th percentile HRRs taken from Table 7-1. The 98th percentile HRR is recommended for screening.
According to Table A5.1, the 98th percentile HRR of an electrical enclosure with a specified configuration and default fuel loading is independent of the type of cables (i.e., thermoset or thermoplastic) it contains.
Issue Date: 05/02/18 1 0609 App F Att 5
Table A5.1 - HRR Profiles for Fixed and Transient Ignition Sources HRR Profile Parameters Ignition Source Configuration* HRRpeak tpeak tsteady tdecay (kW) (s) (s) (s)
Motors NA 69 720 480 1200 Pumps NA 211 720 480 1200 Loose Transients NA 317 120 120 480 Contained Transients NA 317 480 180 480 Small Electrical Enclosures (V 12 ft3) Open or Closed 45 720 480 1200 Enclosure MCCs & Battery Chargers Closed 130 720 480 1200 Set 1 Switchgear & Load Centers Closed 170 720 480 1200 Power Inverters Closed 200 720 480 1200 Medium Enclosures (12 ft3 < V 50 ft3) Closed 200 720 480 1200 Enclosure Medium Enclosures (12 ft3 < V 50 ft3) Open 325 720 480 1200 Set 2 Large Enclosures (V > 50 ft3) Closed 400 720 480 1200 Large TP Enclosures (V > 50 ft3) Open 1000 720 480 1200
- See Attachment 3 for definition of open and closed cabinets HRR Profile of Electrical Cabinet Fires (HEAF)
Switchgear and load centers (440V and above) are subject to high energy arcing faults (HEAFs) in addition to the possibility of a general or thermal fire. As a result, two ignition scenarios need to be considered for electrical cabinets 440 V; HEAF and non-HEAF. For the HEAF scenario, the vertical ZOI is within 5 ft. above the top of the cabinet, and the horizontal ZOI is within 3ft. of all sides of the cabinet. All unprotected targets within this region are assumed to be damaged instantaneously when the HEAF occurs and all unprotected secondary combustibles within the region are assumed to ignite instantaneously. The HRR profile for a HEAF fire has no t-squared growth stage. The HEAF fire reaches HRRpeak instantaneously at ignition (t = 0 seconds),
remains at HRRpeak for 1200 seconds, and subsequently decays linearly to 0 kW in 1200 seconds. The ZOI and HRR profile for non-HEAF scenarios is determined in the same manner as for electrical cabinets < 440 V.
HRR Profile of Main Control Board Panel Fires The HRR of Main Control Board (MCB) panel fires used in an analysis to determine the probability for control room abandonment is identical to that for the electrical enclosures with the same volume.
HRR Profile for Propagating Electrical Cabinet Fires Electrical cabinet fires can be assumed not to propagate to adjacent cabinets if at least one of the following conditions are met:
The cabinets are separated by a double wall with an air gap, or Either the exposed or exposing cabinet has an open top, and there is an internal wall, possibly with some openings, and there is no diagonal cable run between the exposing and exposed cabinet.
Issue Date: 05/02/18 2 0609 App F Att 5
If neither of these conditions are met, electrical cabinet fires are assumed to propagate from the exposing cabinet to adjacent exposed cabinets. There can be one or two exposed cabinets, depending on whether the fire originates in a cabinet located at one end of a bank or in a cabinet that has adjacent cabinets on both sides, respectively. The HRR profile of a propagating cabinet fire is obtained by combining the HRR profiles of the exposing and exposed cabinets, assuming the exposed cabinets ignite 10 or 15 minutes after the exposing cabinet:
Assume an ignition delay of 10 minutes if the cabinets are not separated by a metal wall, or if the cabinets are separated by a single metal wall and cables in the adjacent cabinet are in direct contact with the wall.
Assume 15 minutes if the cabinets are separated by a single metal wall, and cables in the adjacent cabinet are not in contact with the wall.
HRR Profile of Transient Combustible The HRR profile for transient combustible fires is of the same form as shown in Figure A5.1.
The corresponding HRR profile parameters are provided in Table A5.1. These fire characteristics bound transient fire sources with the following characteristics:
A single plastic or metal trash can of up to 55 gallons size loaded with general waste materials such as paper, packing materials, etc.
Up to three small office-size trash cans with general waste (e.g., on the order of 2-4 gallons each, typically either plastic or fiberglass construction).
A single wooden pallet.
A single small packing crate (no more than 24" cube).
A plastic bucket of up to 7 gallons in size (e.g., a used paint bucket) with cleaning materials (e.g., rags, brushes, no more than a pint of cleaning solvents).
One or two plastic trash bags containing general waste materials.
An open grease bucket up to one gallon.
A single collection bin for protective clothing (e.g., at a step-off / dress-out area).
If, in the judgement of the analyst, the as-found conditions exceed the above examples, the fire intensity may have to be increased to reflect the as-found conditions. In that case it is recommended that additional guidance be sought from either the Regional or Headquarters fire protection staff.
OIL FIRES Liquid fuel spills can be confined or unconfined. For confined liquid fuel pool fires the area is known and the HRR is a function of the size of the containment area (pool) and combustion properties of the fuel. The area of an unconfined liquid fuel spill is a function of the spill volume, and the HRR is therefore a function of the volume and combustion properties of the spilled fuel.
Two distinct oil spill fires may need to be considered. The first scenario assumes a spill of 100% of the amount of oil that can be spilled. The second scenario considers a 10% spill. A severity factor of 0.02 is assigned to the first scenario, and 0.98 is used for the second scenario.
For confined liquid pool fires it is not necessary to evaluate the two scenarios separately if the containment area is large enough to hold 100% of the amount of oil that can be spilled.
Issue Date: 05/02/18 3 0609 App F Att 5
Confined Liquid Pool Fires Table A5.2 gives the steady HRR and burning rate of confined liquid pool fires as a function of the pool diameter for the following liquid fuels: (1) diesel fuel and fuel oil, (2) lube oil and mineral oil, and (3) silicone fluid.
Table A5.2 - HRRs and Burning Times for Confined Liquid Pool Fires Diesel Fuel & Fuel Oil Lube Oil & Mineral Oil Silicone Fluid Deff HRR Burning Rate HRR Burning Rate HRR Burning Rate (ft.)
(kW) (gal/min) (kW) (gal/min) (kW) (gal/min) 1.0 41 0.017 25 0.011 2.7 0.002 1.5 123 0.051 81 0.037 8.5 0.005 2.0 262 0.108 183 0.083 19 0.011 2.5 460 0.190 341 0.154 34 0.020 3.0 720 0.297 562 0.253 55 0.032 3.5 1039 0.428 851 0.383 82 0.047 4.0 1418 0.584 1213 0.546 116 0.067 4.5 1854 0.764 1650 0.743 155 0.089 5.0 2345 0.966 2165 0.975 200 0.116 5.5 2890 1.191 2759 1.242 252 0.145 6.0 3487 1.437 3432 1.545 310 0.179 6.5 4136 1.705 4185 1.884 373 0.215 7.0 4836 1.993 5017 2.258 443 0.255 7.5 5586 2.302 5928 2.668 518 0.299 8.0 6386 2.632 6917 3.114 599 0.345 8.5 7236 2.982 7984 3.594 685 0.395 9.0 8135 3.353 9128 4.108 777 0.448 9.5 9083 3.744 10347 4.657 874 0.504 10 10082 4.156 11640 5.240 977 0.563 11 12227 5.040 14448 6.504 1197 0.690 12 14570 6.006 17544 7.897 1438 0.829 13 17114 7.054 20921 9.417 1700 0.980 14 19858 8.185 24574 11.06 1981 1.142 15 22802 9.399 28498 12.83 2283 1.316 16 25948 10.70 32689 14.71 2604 1.501 17 29296 12.08 37145 16.72 2946 1.698 18 32846 13.54 41862 18.84 3308 1.907 19 36598 15.09 46839 21.08 3690 2.127 20 40553 16.72 52075 23.44 4091 2.358 21 44710 18.43 57570 25.91 4513 2.602 22 49070 20.23 63322 28.50 4956 2.857 23 53633 22.11 69332 31.21 5418 3.123 24 58398 24.07 75600 34.03 5901 3.401 25 63366 26.12 82126 36.97 6404 3.691 Issue Date: 05/02/18 4 0609 App F Att 5
For non-circular fires with an area Af, an equivalent effective diameter is used, which is calculated as follows:
4Af Deff = [5-2]
Liquid pool fires are conservatively assumed to reach the steady HRR instantaneously at ignition (t=0 seconds). The burning time can be calculated by dividing the spill volume by the burning rate.
Unconfined Liquid Spill Fires Table A5.3 gives the steady HRR and burning time of unconfined liquid spill fires as a function of spill volume for the same three liquid fuels.
Table A5.3 - HRRs and Burning Times for Unconfined Liquid Spill Fires Diesel Fuel & Fuel Oil Lube Oil & Mineral Oil Silicone Fluid V
HRR Burning Time HRR Burning Time HRR Burning Time (gal)
(kW) (s) (kW) (s) (kW) (s) 1 2438 226 2265 222 209 1880 2 5126 215 5368 188 472 1668 3 7797 212 8696 174 742 1590 4 10451 211 12121 166 1014 1551 5 13095 210 15592 162 1286 1529 6 15732 210 19085 158 1558 1516 7 18366 210 22588 156 1828 1507 8 20997 210 26093 154 2098 1500 9 23627 210 29597 153 2367 1496 10 26255 210 33098 152 2636 1493 11 28883 210 36595 151 2904 1490 12 31143 212 39599 153 3134 1506 13 33059 216 42144 155 3329 1536 14 34950 220 44654 158 3522 1564 15 36820 224 47132 160 3712 1590 16 38668 228 49580 163 3900 1614 17 40498 231 52002 165 4086 1637 18 42310 234 54398 167 4270 1659 19 44106 237 56771 169 4452 1679 20 45886 240 59122 170 4633 1699 21 47653 242 61453 172 4812 1717 22 49406 245 63764 174 4990 1735 23 51146 247 66057 175 5166 1752 24 52874 250 68334 177 5341 1768 25 54591 252 70594 178 5515 1784 26 56298 254 72838 180 5688 1798 27 57994 256 75069 181 5860 1813 28 59680 258 77285 183 6031 1827 29 61357 260 79488 184 6201 1840 30 63026 262 81679 185 6370 1853 Issue Date: 05/02/18 5 0609 App F Att 5
CABLE TRAY FIRES Fires in Vertical Stacks of Horizontal Cable Trays Vertical stacks of horizontal cable trays located within the zone of influence (ZOI) of an ignition source may act as secondary combustibles and contribute to the HRR in the area under evaluation. Tables and plots of the combined HRR as a function of time for various cable types (TS and TP), tray widths (1.5 or 3.0 ft.), and ignition source/cable tray configurations can be found in table/plot set C in Attachment 8. These tables and plots are applicable for non-HEAF scenarios. For HEAF scenarios, add HRRpeak of the ignition source to the cable tray HRR from Figures C.01 (for 1.5 ft. wide trays) or C.02 (for 3.0 ft. wide trays) in Attachment 8.
Flame spread and fire propagation characteristics for fires involving stacks of cable trays are discussed in the section for FDS 2 scenarios in Attachment 3 and in Section 06.03.03 of the basis document (IMC 0308 Attachment 3 Appendix F). It can be assumed that flame spread and fire propagation will not occur under the following conditions:
All trays within the ZOI are fully enclosed, i.e., they have solid bottom and top covers.
All trays within the ZOI have solid bottoms and are tightly covered with at least one in. of ceramic fiber blanket (e.g., Kaowool)
All trays are within the ZOI are protected with a rated fire barrier or wrap, except for HEAF scenarios, in which case wraps within the ZOI are assumed to be destroyed and ineffective.
Vertical Cable Tray Fires The HRR of a vertical cable tray is conservatively estimated as the product of the width of the tray covered with cables, the height of the tray, and the HRR per unit area (HRRPUA) of the cables. The latter is equal to 150 kW/m2 for TS cables, and 250 kW/m2 for TP and Kerite cables (from NUREG/CR-7010). Flames are assumed to spread very rapidly in the vertical direction, and the HRR is therefore assumed to be instantaneous at ignition.
Self-Ignited Cable Fires The HRR profile of vertical stacks of horizontal cable trays involved in a self-ignited cable fire scenario can be obtained from Figures C.01 (for 1.5 ft. wide trays) or C.02 (for 3.0 ft. wide trays) in Attachment 8. A conservative estimate of the HRR of a vertical self-ignited cable tray can be obtained as discussed in the previous section.
HOT WORK FIRES For hot work fires, it will be assumed that the hot work leads to ignition of either transient combustibles, exposed cables, or insulation materials depending on the specific situation.
Transient combustibles could include flammable materials used in conjunction with the hot work itself (e.g., plastic sheeting or non-fire retardant scaffold materials).
If the hot work is assumed to ignite transients, treat the subsequent fire like any other transient fuel fire. As-found conditions may be reflected in fire characterization.
Issue Date: 05/02/18 6 0609 App F Att 5
If the hot work is assumed to ignite exposed cables, treat the subsequent fire like a self-ignited cable fire.
If the hot work fire is assumed to ignite insulation materials, seek additional guidance from Regional or Headquarters fire protection staff.
SEVERE FIRES INVOLVING THE MAIN TURBINE GENERATOR SET For inspections involving the turbine building, a need to address severe fires involving the main turbine generator set may arise. In this case, additional guidance will be needed to complete the Phase 2 analysis. Guidance from either Regional or Headquarters fire protection staff should be sought in the treatment of these fires.
HYDROGEN FIRES If for a given fire area, hydrogen fires might be a significant factor in the risk quantification, additional guidance will be needed to complete the Phase 2 analysis. Guidance from either Regional or Headquarters fire protection staff should be sought in the treatment of these fires.
Issue Date: 05/02/18 7 0609 App F Att 5
ATTACHMENT 1 Revision History for IMC 0609, Appendix F Attachment 5 Comment Description of Accession Resolution and Commitment Training Number Feedback Form Tracking Description of Change Required and Issue Date Accession Number Number Completion Change Notice (Pre-Decisional, Date Non-Public) 05/28/2004 IMC 0609, App F, Att 5 Characterizing Non-Simple Fire None N/A CN 04-016 Ignition Sources, is added to provide guidance on the need to consider whether non-simple ignition sources such as self-ignited cable fires, energetic electrical arcing faults, transient combustibles, hot work, liquid fuel spills, and hydrogen are plausible fire ignition sources.
02/28/2005 IMC 0609, App F, Att 5 Characterizing Non-Simple Fire CN 05-007 Ignition Sources, is revised to change all references from 50th and 95th percentile to 75th and 98th percentile, respectively, for expected and high confidence fire intensity values.
ML17089A422 Revised to reflect changes to the Phase 2 process and for November 2017 ML17093A184 DRAFT consistency with the guidance in NUREG/CR-6850 and CN 17-XXX superseding guidance in NFPA 805 FAQs and NUREG-2178.
CA Note sent 7/18/17 for information only, ML17191A681.
Issued 10/11/17 as a draft publically available document to allow for public comments.
ML18087A409 Draft document revised to incorporate minor public comments Gap training ML17093A184 05/02/18 and re-issued with new accession number in order to issue as covering CN 18-010 an official revision after receipt of public comments. changes to the procedure completed November 2017 Issue Date: 05/02/18 Att1-1 0609 App F Att 5