ML20212G411
| ML20212G411 | |
| Person / Time | |
|---|---|
| Site: | Duane Arnold  |
| Issue date: | 10/28/1997 |
| From: | Kelly G NRC (Affiliation Not Assigned) |
| To: | Leslie Liu IES UTILITIES INC., (FORMERLY IOWA ELECTRIC LIGHT |
| References | |
| GL-88-20, TAC-M83618, NUDOCS 9711060166 | |
| Download: ML20212G411 (8) | |
Text
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _. _ _ _.
, hir. Lee Liu October 28, 1997 Choirnoi of the Board and Chief Executive Ollicer IES Utilities Inc.
200 First Street, SE.
P.O. Box 351 Cedar Rapids, IA 52406 0351 SUIDECT: DUANE ARNOLD ENERGY CENTER - REQUEST FOR ADDIT'ONAL INFORhtATION ON INDIVIDUAL PLANT EXAhilNATION OF EXTERNAL EVENTS (IPEEE)(h183618)
Dear h1r. Liu:
On November 15,1995, you submitted the Individual Plant Examination of External Events (IPEEE) for the Duane Amold Energy Center (DAEC) pursuant to Generic Letter 88 20, Supplemer.( No. 4, which required each licensee and each Construction Permit holder to conduct an examin ition ofits plant (s) for vulnerabilities to extemal events. We have reviewed the DAEC IPEEE submittal, and have developed the enclosed request for additional infonnation (RAl).
These questions are on fire, high winds, external ficoding, and other external events.
Please provide your response within 60 days so that the NRC can complete its review promptly.
If you have any questions about our review, please contact me at (301) 415-3028.
This request for information afTects fewer than 10 respondent:; therefore, Oh1B clearance is not required under Pub. L. 96 511.
Sincerely.
Original si Glenn B. Kelly,gnecj by:Semor Project hianager Project Directorate 1113 Division of Reactor Projects lil/lV f
Office of Nuclear Reactor Regulation 4
Docket No. 50-331 i
i
Enclosure:
Request for AdditionalInfinmation cc w/ encl: See next page
[J[b Distribution:
Docket File PUBLIC PDlli-3 R/F ACRS GGrant, Rill EAdensam(EGAl)
ABusiik OGC,015B18 Ghiarcus G:\\DUANEARN\\83618RALWPD To receive a copy of this document. 6ndecoto in the bor *C* = Copy without attachment / enclosure
- E' = Copy w6th attachment / enclosure
- N* = No copy 0FFICE PM:PDill;3,
/ LA:PDIII 3 NAME GKellyv') M CBoyle
- r bbab_h $O9Y DATE 10/ri/97 10/
/97 OFFICIAL RECORD COPY 9711060166 971028 PDR ADOCK 05000331 F
PDR c,
._ Mr. Lee Liu October 28,-1997 Chairman of the Board and ChiefExecutive Officer o
IES Utilities Inc.
200 First Etreet, SE.
P.O. Bov 351 Cedar epids,IA 52406-0351
SUBJECT:
DUANE ARNOLD ENERGY CENTER - REQUEST FOR ADDITIONAL INFORMATION ON INDIVIDUAL PLANT EXAMINATION OF EXTERNAL EVENTS (IPEEE)(M83618)
Dear Mr. Liu:
On November IS,1995, you submitted the Individual Plant Examination of External Events (IPEEE) for the Duane Amold Energy Center (DAEC) pursuant to Generic Letter 88-20, -
Supplement No. 4, which required each licensee and each Construction Permit holder to conduct an examination ofits plant (s) for vulnerabilities to external events. We have reviewed the DAEC -
4 IFEEE submittal, and have developed the enclosed request for additional information (RAI).
Th:se questions are on fire, high winds, extemal flooding, aad other external events.
Please provide your response within 60 days so that the NRC can complete its review promptly.
Ifyou have any questions about our review, please contact me at (301) 415 3028.
This request for information affects fewer than 10 respondents; therefere, OMB clearance is not required under Pub. L.96-511.
Sincerely, Oriainal sianed by:
Glennll. Kelly, Senior Project Manager Project Directorate III-3 Division of Reactor Projects III/IV Office of Nuclear Reactor Regulation s
Docket No. 50-331 Encicrure: Request for AdditionalInformation t
cc w nel: See next page Distribution:
Docket File PUBLIC PDIII-3 R/F ACRS GGrant, RIII EAdensam(EGAl)
ABuslik OGC,015B18-GMarcus G:\\DUANEARN\\83618RAI.WPD To vece6ve e copo of this document. Indoste in the bos: *C" = Copy wMhout ettechment/ enclosure ' *E' - Copy with attachment / enclosure
- N' = No copy 0FFICE PM:PDIII;'t
[4 LA:PDIII-3l GKelly d %[
CBoyle
/
NAME DATE 10/W/97 10/ /97 0FFICIAL RECORD COPY M
1 Lee Liu Duane Arnold Energy Center IES Utilities Inc.
cc:
Jack Newman, Esquire Kathleen H. Shea, Esquire Morgan, Lewis, & Bockius 1800 M Street, NW.
L Washington, DC 20036-5869 E
Chairman, Linn County Board of Supervisors Cedar Rapids,IA 52406
(
IES Utilities Inc.
L ATTN: Gary Van Middlesworth Plant Superintendent, Nuclear 3277 DAEC Road Palo, IA 52324 r
h John F. Franz, Jr.
4
(')
Vice President, Nuclear y
Duane Arnold Energy Center 3277 DAEC Road Palo, IA 52324 Ken Peveler Manager of Regulatory Performance Duane Arnold Energy Center 3277 DAEC Road Palo,IA 52324 U.S. Nuclear Regulatory Commission Resident inspector's Office Rural Route #1 Palo, IA 52324 Regional Administrator, Rill U.S. Nuclear Regulatory Commission 801 Warrenville Road Lisle, IL 60532-4531 PLrween Baig Utilities Divisio^
5 lowa Department of Commerce Lucas Office Building,5th floor Des Moines, IA 50319
[
--m---
REQUEST FOR ADDITIONAL INFORMATION REGARDING DUANE ARNOLD ENERGY CENTER (DAEC)
INDIVIDUAL PLANT EXAMINATION OF EXTERNAL EVENTS (IPEEE)
FIRE 1.
The IPEEE submittal for DAEC dated November 15, 1995, showed that the fire assetsment credits human reco try actions used in the probabilistic safety assessment probabilistic sorety assessment (PSA). The submittal does not indicate if the quantification of the failure probabilities for these actions considers the potential stresses or other influences (e.g., smoke, heat, loss of lighting, poor communication) induced by a
- fire, (a) Provide a discussion on the human actions modeled in the assessment and whether a fire can influence the associated human error probabilities.
(b) Indicate whether such influences were incorporated into the human error analysis.
(c) If fire-induced influences are identified, but have not been incorporated into the evaluation, provide an assessment of this impact on the results.
2.
The fire assessment estimated the core damage frequency from fires by assuming all fires result in a transient, Address the potential for a fire inducing a loss of Coolant Accident (LOCA) particularly through the occurrence of hot shorts, 3.
The description of unsuppressed fires in the main control room implies that the frequency of core damage is the product of the fire frequency (IE-2/yr), the failure of manual suppression (IE-3), and the failure to.
shutdown the reactor from the remote shutdown panel (IE-1),
Explain why the product of these numbers (IE-6/yr) does not agree with the 1E-7/yr value reported in the text, 4.
The fire modeling for fire compartment 2A/2B/2C uses a heat rate value for a Motor Control Center (MCC) fire of 65 Btu /s that apparently comes from the EPRI " Fire PRA Implementation Guide," This value appears to have been selected based on the results of Sandia National Laboratories (SNL) control panel fire test data.
In the review of NSAC/181 conducted hv SNL, this value was identified as nonrepresentative of MCC fires since MCC fires can be more energetic.
Furthermore, some control panel fire tests that resulted in heat rates as high as 1171 Btu /s were apparently ignored in the selection of the 65 Btu /s value, I
(a) Justify the value used, or provide an analysis of the effect on risk if the MCC fire heat rate value is increased significantly for this fire -
compartment and others that used the 65 Btu /s heat rate (e.g., 3A/3B).
(b) In addition, the fire modeling for this compartment used a cable damage threshold temperature of 983'F that is significantly above the approved FIVE criteria of 700'F for IEEE 383 qualified cables.
Reevaluate the potential for fire propagation in this compartment and other compartments (e.g.
3A/2B) using 700'F.
5.
Table 4-10 in the submittal shows that the core damage frequencies after the fire propagation analysis for fire compartments 2A/2B/2C and 3A/3B are less than 1E-6/yr However, the sum of the individual fires appears to add up to greater than 1E-6/yr.
It is recognized that no attempt was made to subdivide the fire frequency for these compartments to correspond to the individual fires analyzed.
However.-until this is done, it cannot be verified that the total core damage frequency for these compartments is below the screening value.
Partition the fire frequency as appropriate, provide documentation of how the frequency is-partitioned and provide the resulting core damage frequencies.
6.
The cable spreading room was dismissed in Table 4-10 as having a negligible fire frequency and conditional core damage frequency.
However, earlier discussion shows the fire frequency.is 5.36E-4/yr and the remote shutdown capability cannot be credited for a fire in this area.
No fire modeling was performed for this area implying that it was screened earlier in the evaluation where all equipment in the area is assumed destroyed by a fire.
Since cables required for safe shutdown following a fire are located in this area.-an all engulfing fire would likely result in a high conditional core damage frequency.
Therefore, the screening of_the cable spreading room is ccrsidered premature.
Provide a discussion about the cable spreading rocm in more detail explaining the basis for its elimination as a risk significant fire compartment.
High Winds, Floods, and other 1.
a.
Wind Pressure Fraaility
-The IPEEE submittal uses a generally accepted formula for the probability of failure of a struci.ure from wind with speed V:
~
3-I n ( V/ ( f,V,) )
pf=ot
)
s Here, o is the cumulative normal distribution function, f, is the median factor of safety, V is the wind speed at which the failure probability is calculated, Va is the design wind speed, and S is the standard deviation of in(V).
This is, so far, a conventional approach.
However, the IPEEE submittal, referencing NUREG/CR-2300, asserts that f,=1.5 is generally applicable to structures, and that s=0,25 is the standard deviation factor recommended by NUREG/CR-2300.
NUREG/CR-2300 does give an example of a wind fragility analysis for a building in Chapter 10, where a factor of safety nf 1.5 is used, but this is just an example. Moreover, even in the example, a s of.25 is not used.
The example treats the random and uncertainty s's separately, and uses s, = 2 and s,=.3.
If a single s is used (generally called a composite s), this corresponds to the mean fragility curve, and is given by Ph+4 This yields, in the NUREG/CR-2300 example, a value of.36, not the.25 used in the submittal.
Insufficient justification for the median factors of safety and s*s is given. The fact that, in an example, NUREG/CR-2300 used a median factor of safety of 1.5 is not sufficient justification.
Please provide a justification for this factor or modify your evaluation.
b.
Hich Wind Accident Secuence Delineation and Screenina The IPEEE submittal screens out F6 tornadoes by arguing that their contribution to the core damage frequency is less than 1E-6 per year.
The intent of the NUREG-1407 screening criteria was to show that the core damage frequency from the aggregate of all wind sequences was less than 1E-6 per year.
It is not valid to separate out the contribution of F6 tornadoes (tornadoes _ with wind speeds between 318 mph and 380 mph).
argue that their contribution is less than the screening criterion, and then continue with the evaluation of the sequences arising from tornadoes with other F-scale intensities, i
V y
4-The argument giving the estimate of the contribution of core damage from F6 category tornadoes is not valid. The IPEEE submittal estimated the frequency of F6 tornadoes as 1.2E-6 per year and argued that the probability of failure of a Category I structure is.04 for a tornado with a mean wind speed in the F6 wind speed range.
It further argued that the frequency of core damage from F6 tornadoes was the product of 1.2E-6 per year and.04, or 4.8E-8 per year. However, this is not valid for Duane Arnold since it is possible, say, that if any of several different Category I structures failed, this would lead to core damage.
For example, failure of any one of the Reactor Building, the Control Building, the Intake Structure, the Turbine Building, or the safety-related portion of the Pump House might lead to core damage._ Then the contribution of F6 category tornadoes to core damage would be 2.4E-7 per year.
Moreover, as noted above, the value of s taken from NUREG/CR-2300, even if it were applicable universally, would be equal to.36 not.25.
With this value of E the probability of failure of a Category 1 structure would be,11. not.04 for an F6 tornado.
Without further analysis, all one can say about the contribution of F6 tornadoes to the core damage frequency is that it is less than their frequency.1.2E-6 per year.
It is not possible to determine the dominant eccident sequences based pm the material presented in the submittal, nor is it possible to verify the validity of the accident sequence delineation and quantification.
Accordingly:
(i)
Justify or revise the median factors of safety and the s's used in ti,e fragility analysis.
(ii)
Correct the analysis using, if necessary, revised values of median factors of safety and s's.
Do not subdivide the wind sequences into subsequences 6ad screen each subsequence out separately.
In particular, do not screen out F6 tornadoes.
(iii)
For the revised analysis, provide the dominant sequences with the contribution of each to the core damage frequency.
2.
NUREG-1407 requests that a licensee " perform a confirmatory walkdown of the plant. The walkdown would concentrate on outdoor facilities that could be affected by high winds, onsite storage of hazardous materials, and offsite developments." Please provide a concise summary of the
5-findings of this walkdown and resolution of_ any identified potential vulnerabilities.
In particular, please provide an assessment of the effects of failure from high winds and tornadoes of non-safety related structures and equipnent on the functioning of safety-related structures, systems, and components.
Supplement 1. discusses further the concern with failure of non-safety-related structures affecting safety-related structures.
3.
As noted in NUREG-1407, section 2.4. the latest piobable maximum precipitation criteria published by the National Weather Service call for higher rainfall intensities over shorter intervals and smaller areas than have previously been considered; this could result in higher site flooding levels, and greater roof ponding levels.
Please assess-the effects of applying these_new criteria to Duane Arnold.
Additional information is given in Generic Letter 89-22.
SEISHIC There are no requests for additional information in this area.
Principal contributor: A. Bus 11k E'_________
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