ML20202F681
| ML20202F681 | |
| Person / Time | |
|---|---|
| Site: | Quad Cities  |
| Issue date: | 11/26/1997 |
| From: | Pulsifer R NRC (Affiliation Not Assigned) |
| To: | Johnson I COMMONWEALTH EDISON CO. |
| References | |
| TAC-M83665, TAC-M83666, NUDOCS 9712090174 | |
| Download: ML20202F681 (12) | |
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November 26. 1997 Ms. Irene Johnson, Acting Manager Nuclear Regulatory Services Commonwealth Edison Company Executive Towers West til
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1400 Opus Place, Suite 500 j
Downers Grove,IL 60515
SUBJECT:
REQUEST FOR ADDITIONAL INFORMATION ON QUAD CITL-S IPEEE c
SUBMITTAL (TAC NOS. M83665 AND M83666)
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Dear Ms. Johnson:
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,4 Based on our ongoing review of the Quad Cities individual Plant Examination of Extemal Eventsf (IPEEE) submittal, we have developed the enclosed rwquests for additional information (RAls).,
The RAls are related to the seismic, fire, and high winds, floods, and transportation and nearby facility accidents (HFOs) analyses in the IPEEE. We have leamed from the meeting held at the g
NRC on August 20,1997, that Commonwealth Edison Company (Comed) intends to update its
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fire IPEEE to include the plant specific improvements proposed for reducing the identified fire risks. Therefore, some of the fire RAls, derived from the submitted IPEEE, may no longer be applicable to the improved plant conditions; nevedheless, they are provided herewith to help Comed focus on the staff's concems and address them, when appropriate, in its update of the fire IPEEE.
We request that you provide your response within 60 days in conformance with our review schedule, if you have any questions conceming our review, please contact me at (301) 415-3016.
Sincerely, Orig signed by Robert M. Pulsifer, Project Manager Project Directorate lll-2 Division of Reactor Projects - lilllV Office of Nuclear Reactor Regulation Docket Nos. 50-254,50-265 hh [ (({U @%
Enclosure:
RAls cc w/ encl: See next page pistribution: (Docket File' PUBLIC PDill 2 r/f E. Adensam, EGA1 R. Capra C.' Moore R. Pulsifer OGC,015B18 ACRS, T2E26 T. Kozak, Rlli J. men DOCUMENT NAME: G:\\CMNTJR\\QUAO\\QCIPEEE.RAI To receive a copy of this document, Indicate in the tqom: *C" = copy without enclosures *E* = Copy wim enclosures *N = No copy p
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November 26,.1997 1
Ms. Irene Johnson, Acting Manager Nuclear Regulatory Services Commonwealth Edison Company Executive Towers West lil 1400 Opus Place, Suite 500 Downers Grove,IL 60515
SUBJECT:
REQUEST FOR ADD:TIONAL INFORMATION ON QJAD CITIES IPEEE SUBMITTAL (TAC NOS. M83665 AND M83666)
Dear Ms. Johnson:
Based on our ongoing review of the Quad Cities individual Plant Examination of Extemal Events (IPEEE) submittal, we have developed the enclosed requests for additional information (RAls).
The RAls are related to the seismic, fire, and high winds, floods, and transportation and nearby facility accidents (HFOs) analyses in the iPEEE. We have loamed from the meeting held at the NRC on August 20,1997, that Commonwealth Edison Company (Comed) intends to update its fire IPEEE to include the plant-specific improvements proposed for reducing the identified fire risks. Therefore, some of the fire RAls, derived from the submitted IPEEE, may no longer be applicable to the improved plant conditions; nevertheless, they are provided herewith to help Comed focus on the staff's concems and address them, when appropriate, in its update of the fire IPEEE.
We reqwst that you provide your response within 60 days in conformance with our review schedule, if you have any questions concoming our review, please contact me at (301) 415-3016.
Sincerely,
/
b ' /. Pulsifer,N Robert Project Manager Project Directorate lil-2 Division of Reactor Projects - lil/IV Office of Nuclear Reactor Regulation Docket Nos. 50-254 and 50-265
Enclosure:
RAls cc w/ encl: See next page ea---r-
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- 1. Johnson Quad Cities Nuclear Power Station Commonwealth Edison Company Unit Nos.1 and 2 cc:
Michael 1. Miller, Esquire Vice Prosident - Law and Sidley and Austin Regulatory Affairs One First National Plaza MidAmerican Energy Company Chicago, Illinois 60603 One RiverConter Place 106 East Second Street Plant Manager P.O. Box 4350 Quad Cities Nuclear Power Station Davenport, Iowa 52808 22710 206th Avenue North Cordova, Illinois 61242 Document Control Desk-Licensing Commonwealth Edison Company U.S. Nuclear Regulatory Commission 1400 Opus Place, Suite 400 Quad Cities Resident inspectors Office Downers Grove, Illinois 60515 22712 206th Avenue North Cordova, Illinois 61242 Site Vice President Quad Cities Nuclear Power Station Chairman 22710 206th Avenue North Rock Island County Board Cordova, Illinois 61242 sf Supervisors 1504 3rd Avenue Rock Island County Office Bldg.
RockIsland,lilinois 61201 lilinois Department of Nuclear Safety Office of Nuclear Facility Safety 1035 Outer Park Drive Springfield, Illinois 62704 Regional Administrator U.S. NRC, Region til 801 Warrenville Road Lisle, Illinois 60532-4351 William D. Leach Manager - Nuclear MidAmerican Energy Company 907 Walnut Street P.O. Box 657 Des Moines, Iowa 50303
QUAD CITIES Request for Additionalinformation Seismic 1.
The reported plant HCLPF [high confidence in low probability of failure) capacity of 0.09g, which credits plant improvements and resolution of Unresolved Safety.
Issue (USl) A-46 concerns, is a very low value. Please describe in detail the,
actions that are being taken to ensure that the plant has adequate seismic margin (i.e., that there is high confidence that the plant will have a high probability of surviving an earthquake greater than the SSE [ safe-shutdown earthquake) level). (In this regard, please clearly describe any completed or planned resolution actions pertaining to USl A-46 and/or IPEEE, additional to those already mentioned in the submittal, that may have an effect on the plant seismic margin.)
2.
The identified backup shutdown path does not employ systems that are substan:ially independent of those relied upon for the primary shutdown path, and hence, the primary and backup success paths collectively have minimal diversity / redundancy. According to seismic margin assessment (SMA) procedures, diverse and independent systems should be employed to the extent possible in attemate success paths. Please provide a complete, detailed justification for use of the current success paths, including consideration of the potential and effects of correlated equipment failures (e.g., failures of ADS 4
[ automatic depressurization system) valves). If necessary, enhance the IPEEE equipment list to include redundant equipment that reflect diverse and independent means for achieving safe shutdown, and report the findings i
pertaining to the SMA evaluation of these additional components.
3.
The submittal does not provide a description of unit differences and does not identify which success path components (a) belong to Unit 1, (b) belong to Unit 2, and (c) are shared among Units 1 and 2. Please identify and describe in detail any differences among the plant units. Please confirm (and justify) whether or not the reported plant HCLPF capacity and other seismic IPEEE results apply equally to Units 1 and 2.
4.
NUREG-1407 (" Procedural'and Submittal Guidance for the individual Plant Examination of External Events (IPEEE) for Severe Accident Vulnerabilities")
requests that screening criteria be applied with respect to non-seismic failares -
and humsn actions. Provide a list of all operator entions that are required to ensure integrity of the chosen success paths. For each human activ 1, indicate the time after the earthquake that the operator action is required and its location.
Enclosure
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Indicate also the human error probabilities, accounting for seismic effects on operator actions. Provide a list of the random failures (and their failure rates) having the most significant potential to compromise integrity of the success paths. Indicate the screening criteria applied to rates of random failures and operator errors, and report the results of your scrooning evaluation.
5.
The assessment of seismic failure or tire suppression systems examined only the potential for adverse interactions with safety equipment; however, it did not examine this issue from the viewpoint of loss of fire suppression capability. For example, in the exan'ination of seismically induced fires, a poorly anchored day tank storing diesel fuel oil for the diesel-driven fire pump was assessed and judged not to be a concern from the viewpoint of a seismically induced " ire; however, this component was not identified as a concern from the viewpoint of seismically induced loss of fire-water capability, in regard to the potential for seismically induc6d loss of capability of fire suppression systems, examples of relevant items found in past studies include (but are not limited to):
Unsinchored CO tanks or bottles 2
Sprinkler standoffs penetrating suspended ceilings Fire pumps unanchored or on vibration isolation mounts Unrestrained batteries / rack for diesel-driven fire pumps Block wall interactions with fire pumps or hatteries Use of cast iron fire mains to provide fire water to fire pumps NUREG-1407 suggests a walkdown as a means of identifying any such items.
Please identify a complete list of instances where weaknesses in fire suppression equipment exist at the plant, as encountered by plant walkdowns, and report your approach for resolution of these weaknesses. Provide guidelines given to walkdown personnel for evaluating these issues (if they exist).
S.
Even for plants characterized as rock sites, there may still exist some soil-founded or buried components (e.g., piping and tanks) or soil structures (including onsite or offsite canals, dams, or embankments) that can affect plant response. Please identify any such components, evaluate their importance to plant safety, evaluate the poter:tial and effects of soil response / failure (including soil settlements / deformations, soil stresses, etc.) on their capacities, and report your misted analyses and findings.
7.
For the following outliers identified in the seismic IPEEE and assessed as having a capacity below the review level earthquake (RLE) (see the table in Section 3.1.5 of the IPEEE submittal for a complete list of such equipment), please provide capacity calculations (including HCLPF calculations), completed 2-
screening evaluation work sheets (SEWSs), walkdown notes / checklists, and photorjaphs:
Cable trays - cable tunnels (LAR 004); surrounding hydraulic control units (HCUs) (LAR 012); cable spreading room (LAR 002); reactor, turbine, and service buildings (LAR 011); and turbine building (LAR 008)
Rocks 2201-32 and 2202-32 Switchgear 23-1,13-1,14-1, 24-1,18,19, 28, 29, 23,13,14, and 24 Silencers 16667,2 6667, WS667 Chargers 2-8350 and 2-8300-1 A Cubicle coolers %, 1, 2-5749, and 1,2-5746A,B, -5747, -5748A,B MCCs 1 B, 2A, 2B,18-1 A,18-1 A-1,18-1 A-1 PNL,18-1 B,18-3,19-1,19 =
1,19-1-1 PNL,19 4, 28-1 A, 28-i A-1, 28-1 B, 28-3, 29-1, 29-1 -1, 29-1-1 PNL,29-4, and Transformer MCOs 28-1 A-1 TR and 29-1-1 TR Panels 901-50 and 901/902-27 Damper 2-9472-32 Switch PE-1 Please provide similar information for masonry block walls adjacent to the following equipment (see Table 3-1 of the IPEEE submittal): SWGR 24-1, SWGR 13-1, SWGR 14-1, and 2252-87. (Note that the calculations for these block walls are all apparently provided in Reference 93C2806.03-C-003.)
(Note: Where multiple components of a given class are listed above, and the walkdown findings end calculations for all such components are essentially identicel, relevant information need only be provided for one representative component of the class.)
8.
Section 6.3.3 of NUREG-1407 statas that "USl A-45... should be specifically addressed as part of the seismic IPEEE." Please report your approach and findings pertaining to the resolution of USl A-C.
9.
Discuss the ability of the primary and backup success paths to respond to medium and large loss-of-coolant accidents (LOCAs) resulting from stuck-open safety-relief valves.
10.
Please provide a list of the comments made by peer reviewers of the seismic IPEEE and indicate how each review comment was resolved.
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Fire i
1.
Please provide the basis foi dismissing fire-induced initiators other than general transients and lost of offsite power, 2.
Was the timing of fire-induced damage considered when allowing credit for automatic suppression of the fire? If not, please provide a re-evaluation of fire scenarios where automatic suppression was creditori, considering the timing of actuation. suppression, and fire damage.
3.
The heat loss factor is defined as the fraction of energy released by a fire that is transferred to the enclosure boundaries. This is a key parameter in the prediction of component damage, as it determines the amount of heat available to the hot gas layer, in the Fire Induced Vulnerability Evaluation (FIVE), the heat loss factor is rnodeled as being inversely related to the amount of heat requirsd to cause a given temperature rise. Thus, for example, a larger heat loss factor means that a larger amount of heat (due to a more severe fire, a ir nger burning time, or both) is needed to cause a given temperature rise. It can b a seen that if the value assumed for the heat loss factor is un,'ealistically high, fire scenarios can be improperly screened out. Figure A.1 provides a espresentative example of how hn gas layer temperature predictions can change assuming different heat loss factors. Note that (1) the curves are computed for a 10004W fire in a 10m x Sm x 4m compartment with a forced ventilation rate of 1130 cfm, (2) the FIVE-recommended damage temperature for qualifien cable is 700 degrees Fahrenheit for qualified cable and 450 degrees Fahrenheit for unqualified cable, and (3) the SFPE curve in the figure is generated from a correlation provided in the Society for Fire Protection Engineers Handbook [1].
Based on evidence provideo by a 1982 paper by Cooper et al. [2), the EPRI IElectric Power Research Institute] Fire PRA Implementation Guide recommends a heat loss factor of 0.94 fer fires with durations greater than 5 minutes and 0.85 for " exposure fires away from a wall and quickly developing hot gas layers."
Howeser, as a general statement, this appears to be a misinterpretation of the results. Reference [2), which documents the results of multi compartment fire experiments, states that the higher heat loss factors are associated with the movement of the hot gas layer from the buming compartment to adjacent, cooler compartments. Eanier in the experiments, where the hot gas layer is limited to the burning compartment, Reference [2] repc<ts much lower heat loss factors (on the order of 0.51 to 0.74). These lower heat loss factors are more appropriate when analyzing a single compartment fire. In summary, (a) hot gas layer predictions are very sensitive to the assumed value of the heat loas factor; and (b) large heat loss factors cannot be justified for single-room scenarios based on the information referenced in the EPRI Firc PRA Implementation Guide.
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Figure A.1 Sensitivity of the hot gas layer temperature pedictions to the assumed heat loss factor For each scenario where the hot gas layer temperature was calculated, please specify the heat loss factor value usedin the analysis, in light of the preceding i
discussion, please either: a) Justify the value used and discuss its effect on the identification of fire vulnerabilities, or b) repeat the analysis using a more justifiable value and provide the resulting change in scenario contribution to core damage frequency.
4.
In computing the extent of fire propagation and equipment damage for a given scenario, it is important that experimental results not be used out of context.
Inappropriate use of experimental results (e.g., employing propagation times specific to a particular cable tray separation to fires involving cable trays with lesser separation) can lead to improper assessments of scenario importance. In one case [3), rather thkn performing fire model calculation and uring the results, experimental data from a test performed to mcdel cable tray fire propagation in the absence of an exposure fire om used to model cable response to an exposure fire, which led to over an order of magnitude reduction in predicted fire-induced core damage frequency.
For oss fire soonerio in whis experimental data were used to estimate the rate and extent of fire propagation, please: (a) indicato if FlVE (or similar) calculations were performed for the scenario and provide the results (equipment i
damaged) of these calcu!ations; (b) indicate whis experimental results were used and how they were utilized in the analysis; and, (c) Justify the applicability of these experimental results to the scenario being analyzed. The discussion on results applicability should compare the geometries, ignition sources, fuel type and loadings, ventilation daracterist'cs, and compartment cimrectoristics of the experimertal setup (s) with those of the scenaric of interest.
5.
Fires in the main control room (MCR) sre potentially risk-significant because they can cause l&C [instnamentation and control) failures (e.g., loss of signals or spurious signals) for multiple redundant divisions, and because they can force control room abandonment. Although data from two experiments conoeming the timing of smoke-induced, foroed control room abandonment is available [4), ine l
l data must be carefully interpreted, and the analysis must properly consider the
-l differences in configuration between the experiments and the actual control i
room being evaluated for fire risk. In particular, the experimental configuration included placement of smoke detectors inside the cabinet in which the fire originated, as well as an open cabinet door for that cabinet. In one case, failure to account for these configuration differences led to more than an order of magnitude underestimate in the conditional probability of forced control room fire abandonment [3). In addition, enother study relees questions about control room habitability due to room air temperature concems [5).
Please provide the detailed assumptions (including the assumed fire frequency, any frequency reduction factors, and the probability of abandonment) used in analyzing the WICR and justifications for these assumptions. In particular, if the probabHity of abandonment is based on a probability distribution for the time required to suppress the fire, please justify the parametric form of the distribution and specify the data used to quantify the distribution parameters.
6.
The EPFsl Fire PRA implementation Guide methodology for evaluating the effectiveness of suppression efforts treats manual recovery of automatic
- suppression systems as being independent of subsequent manual efforts to suppress the fire. This assumption is optimistic, as the fire conditions (e.g.,
heat, smoke) that lead to the failure of recovery efforts can also influence the l
odectiveness of later suppression efforts. Such an approach, therefore, can -
1 overlook plant specific vulnerabilities, it is important that all relevant factors be considered in an evaluation of the l
effectiveness of fire suppression. These factors include (a) the delay between ignition anJ detector / suppression system actuation (which is specific to the configuration being analyzed), (b) the time-to-damage for the critical component (s) (which is specific to the fuel type and loading as well as to the configuration being rnodeled), (c) the response time of the fire brigade (which is 6-
..---.=- -.-------..--.a.-..
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plant-specific and fire-location-specific), (d) the time required by the fire brigade to diagnose that automatic suppression has failed and to take manual action to recover the automatic suppression system, and (e) PSFs [ performance shaping factors) affecting fire brigade actions. These PSFs could include factors such as perseverance (persistent efforts made to recover a failed automatic suppression system), smoke obscuration, and imoeired communications [3).
Finally, it should be noted that the Nuclear Regulatory Commission (NRC) staffs evaluation of the FIVE methodology [6] specifically stated that licensees need to assess the offectiveness, of manuel fire-fighting teams by using plant specific data from fire brigade training to determine the response time of the fire fighters.
Please identify those scenarios for which credit is taken for both manual recovery of automatic suppression systems and manual suppression of the fires (if manual recovery efforts are unsuccessful), and please indicate the plant equipment that may be affected by the fires. In the analysis of these scenarios, how are dependencies between mar ual actions treated? Please jur.tify the treatment, considering the expected tire environment, the recovery actions required, and the manual fire suppression actions required.
7.
The EPRI Fire PRA Implementation Guide assumes that all enclosed ignition sources cannot lead to fire propagation or other damage (page 4'-18 of [1]).
This can be an optimistic assumption for oil filled transformers and high voltage cabinets. The Guide also assumes that fire spread to adjacent cabinets cannot occur if the cabinets are separated by a double wall with an air gap or if the cabinet in which the fire originates has an open top (page H-3 of [1]). This can also be an optimistic assumption for high-voltage cabinets since an explosive 4
breakdown of the electrical conductors may breach the integrity of the cabinet and allow fire to spread to combustibles located above the cabinet. For example, switchgear fires at Yankee-Rowe in 1984 and Oconee Unit 1 in 1989 both resulted in fire damage outside the cubicles.
Please provide the basis for the assu nption and a discussion on how the specific enclosures were analyzed to ascertain that the assumption is applicable to them.
8.
In the EPRI Fire PRA implementation Guide, test results for the control cabinet heat release rate have been misinterpreted and have been inappropriately extrapolated. Cebinet heat release rates as low as 65 Btu /sec are used in the Guide. In contrast, experimental work has devaloped heat release rates ranging from 23 to 1171 Blu/ soc Considering the range of heat release rates that could be applicable to different control cabinet fires, and to ensure that cabinet fire areas ata not prematurely screened out of the analysis, a heat release rate in the mid-range of the 7
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currently available Warimental data (e.g., 550 Btu /sec) should be used for the analysis.
Discuss the heat release rates used in your assessment of control cabinet fires.
Please provide a discussion of changes in the IPEEE fire assessment results if it is assumed that the heat roles)e from a cabinet fire is increased to 550 Stu/s.
9.
In general, the fire risk associa..d with a given compartment is composed of contributions from fixed and transient ignition sources. _ Noglect of either contribution can lead to an underestimate of the comp artment's risk and, in some cosec, to improper screening of fire scenarios. The E.8RI Fire PRA
[
ImpAemenfation Guide allows the sorooning of transier.1 ignition sources in compartments where all fixed ignition sources have been screened out. Based L
on this approach, a cable spreading room or a cable shaft that doos not contain l
any items other than IEEE 383 qualified control and instrumentation cables, and access to the compartment is strictly controlled, can be screened out. If such compartments contain the cables for all redundant trains of important plant safetv systems, a major vulnerability may be overlooked, without sufficient
- analysis of potential accident sequences and needed recovery actions.
in compartments where all fixed ignitions sources have been screened out, has i
the possibility of transient combustible fires been considered? For each compartment where transient fires have not been considered, please provide the justification for this conclusion and provide a discussion on compartment inventory in terms of system trains and associated components (i.e, cables and other equipment).
Please explain whether or not the conditional core damage probabilities, given damage to all cables and equipment in these compartmer,ts, are significant (i.e., cables from redundant trains are present). If the conditional core damage probability for a compartment is considered significant, please provide justification for assigning a very low likelihood of occurrence to transient
'uel fires for the compartment.
10.
Please provide a list of multi-compartment fire scenarios that were screened out based upon a lack of hot gas layer formation.
High Winds, Floods, and Others
. 1.
Please provide the analysis concoming the probable maximum precipitation (GI-103), as requested in NUREG 1407, References for Fire RAls i
1 P.J. DiNonno, et al., eds.; 'SFPE Handbook of Fire Protection Engineering,' 2nd Edition, National Fire Protection Association, p 3-140,1995.
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2.
L. Y. Cooper, M. Harkleroad, J. Quintiere, W. Rinkinen, 'An Experimental Study 1 Upper Hot Layer Stratification in Full-Scale Multiroom Fire Scenarios,' ASME Joumal of Heat Trantbr,,1Qs, 741-749, November 1982.
3.
J. Lambright, et al., "A Review of Fire PRA Requentification Studies Reported in NSAC/181," prepared for the United States Nuclear Regelstory Commission, April 1994.
4.
J. Chavez, et al., ",4. Experimental investigation of intomally ignited Fires in Nuclear Power Plant Cabinets, Part Il-Room Effects Tests," NURFG/CR-4527N2 October 1988.
5.
J. Usher and J. B xcio, ' Fire Environment Determination in the LaSalle Nuclear l
Power Plant Control Room,' NUREG/CR-5037, prepared for the United States Nuclear Regulatory Commission, October 1987.
r 6.
A. Thadani, 'NRC Staff Evaluation Report on Revised NUMARC/EPRI Fire Vulnerability Evaluation (FIVE) Methodology,' U.S. Nuclear Regulatory t
Commission, August 21,1991 (letter to W. Rasin, NUMARC, with enclosure,
' Staff Evaluation of the Fire Vulnerability Evaluation (FIVE) Methodology for Use in the IPEEE').
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