ML20203H141

Forwards Request for Addl Info Re IPEEE Submittal

ML20203H141
Person / Time
Site:	Clinton
Issue date:	02/25/1998
From:	Hopkins J NRC (Affiliation Not Assigned)
To:	Sipek J ILLINOIS POWER CO.
References
TAC-M83607, NUDOCS 9803030163
Download: ML20203H141 (9)

Text

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February-25, 1998' -

Mr. Joseph V. Sipek -

Director-Licensing -

4 Clinton Power Station P.O. Box 678 Mail Code V920' Clinton,IL 61727

SUBJECT:

INDIVIDUAL PLANT EXAMINATION OF EXTERNAL EVENTS (TAC NO.- M83607)

Dear _ Mr. Sipsic Based on our ongoing review of the Clinton Individual Plant Examination of Extemal Events-(IPEEE) submittal, we have developed the attached request for additional information (RAI),

l The RAl ls related to the IPEEE analyses in the seismic and fire areas, and was developed by our contractors, Brookhaven and Sandia National Laboratories, respectively. There are no -

questions related to high winds, floods, and other external event areas. The questions have-been reviewed by an NRC Senior Review Board with probabilistic risk assessment expertise -

for external events. - Please respond to the RAI within 60 days of receipt of this letter.

Contact me if you have any questions.

Sincerely, Original signed by:

- Jon B. Hopkins, Senior Project Manager -

Project Directorate Ill-3 Division of Reactor Projects lil/lV i

Office of Nuclear Reactor Regulation Docket No. 50-461 Distnbution' Docket File PUBLIC

Enclosure:

- Requd for Additional PD3-3 RIF ACP.S.

I Information ARubin -

OGC-s EGA1 GGrant, Rlli -

cc w/ encl: See next page RSavio Document Name: G:\\CLINTON\\lPEEE.RAI 0FFICE PM:PDIII-3--

lE. LA:PDIII-3 l(L v7o Em q pa w n capy y NAME JHopkins-

/)b EBarnhill [7P-UUb DATE c% /p4/98 4/

- a /ar/98 0FFICIAL RECORD COPY 9803030163 990255 D

February 25, 1998 Mr. Joseph V. Sipek Director-Licensing Clinton Power Station P.O. Box 678 Mail Code V920 Clinton,IL 61727

SUBJECT:

INDIVIDUAL PLANT EXAMINATION OF EXT ERNAL EVENTS (TAC NO. M83607)

Dear Mr. Sipek:

Based on our ongoing review of the Clinton Individual Plant Examination of Extemal Events (IPEEE) submittal, we have developed the attached request for additional information (RAI).

]

The RAI is related to the IPEEE analyses in the seismic and fire areas, and was developed by our contractors, Brookhaven and Sandia National Laboratories, respectively. There are no questions related to high winds, floods, and other external event areas. The qv;stions have been reviewed by an NRC Senior Review Board with probabilistic risk assessment expertise for extemal events. Please respond to the RAI 'ithin 60 days of receipt of this letter, Contact me if you have any questions.

Sincerely, Original signed by:

Jon B. Hopkins, Senior Project Manager Project Directorate 1113 Division of Reactor Projects Ill/lV Office of Nuclear Reactor Regulation Docket No. 50-461 Distribution:

Docket File PUBLIC

Enclosure:

Request for Additional PD3-3 R/F ACRS Information ARubin OGC EGA1 GGrant, Rlli cc w/ encl: See next page RSavio Document Name: G:\\CLINTON\\lPEEE.RAI 0FFICE PM:PDIII-3 EL LA:PDIII-3 l 0_.

NAME JHopkins

/)b EBarnhill (fr-DATE fL. /;;Ls'/98 4/

a /ar/98 0FFICIAL RECORD COPY

$a atoyA UNITED STATES y

j NUCLEAR RECULATORY COMMISSl!N j

g WASHINGTON, D.C. 30eeH001 49.....

February 25, 1998 Mr. Joseph V. Sipek Director-Licensing Clinton Power Station P.O. Box 678 Mail Code V920 Clinton,IL 61727

SUBJECT:

INDIVIDUAL PLANT EXAMINATION OF EXTERNAL EVENTS (TAC NO. M83607)

Dear Mr,

Sipek:

Based on our ongoing review of the Clinton Individual Plant Examination of Extemal Eventr, (IPEEE) submittal, we have developed the attached request for additional information (R/J).

l The RAI is related to the IPEEE analyses in the seismic and fire areas, and was develoyd by l

our contractors, Brookhaven and Sandia National Laboratories, respectively. There ara no l

questions related to high winds, floods, and other extemal event areas. The questions have i

been reviewed by an NRC Senior Review Board with probabilistic nsk assessment expertise for extemal evente. Please respond to the RAI within 60 days of receipt of this letter.

. Contact me if you have any questions.

Sincerely, o

Jon B. Hopkins, Seni Project Manager Project Directorate 111-3 Division of Reactor Projects lil/IV Office of Nuclear Reactor Regulation Docket No. 50-461 Enclosuro: Request for Additional Information cc w/ encl: See next page

- Joseph V. Sipok Clinton Power Station, Unit 1

. lilinois Power Company cc:

John G. Cook lilinois Department of Nuclear Safety -

Senior Vice President Office of Nuclear Facility Ssfety -

Clinton Power Station ~

1035 Outer Park Drive P.O. Box 678 -

Springfield,IL 62704 Clinton,IL 61727 -

Larry Wigley Manager Nuclear Station Engineering Department Clinton Power Station

. P.O. Box 678 '

Clinton,IL 61727 Resident Inspector U.S. Nuclear Regulatory Commission RR#3, Box 22g A L

Clinton,IL 61727

- R. T. Hill -

Licensing Services Manager

-_ General Electric Company i

175 Curtner Avenue, M/C 481 San Jose, CA g5125

. Regional Administrator, Region lll U.S. Nuclear Regulatory Commission 801 Warrenville Road Lisle, IL 60532-4351 Chairrnan of DeWitt County --

clo County Cisrk's Office DeVAtt County Courthouse Clinton, IL 61727 -

J. W. Blattner Project Manager-Sargent & Lundy Engineers 55 East Monroe Street -

Chicago,IL 60603' b

REQUEST FOR ADDITIONAL INFORMATION CLINTON POWER STATION Docket No. 60 461 Selsmic 1)

According to the Individual Plant Examination of Extemal Events (IPEEE) submittal, the preferred success path for the Clinton Power Station (CPS) relies on the rascter core isolation cooling (RCIC) system, and RCIC alor.a, for reactor coolant system (RCS) inventory contre.. The RCIC system, which uses a turbine-driven pump, is a single train syrNm with only moderate reliability. According to EPRI NP 6041,'the use of single-train syctnTis with recognized poor availability

• should be ' treated with caution * (for non-seismic caused component or system unavailability). EPR4 NP-6041 further states that

'ono should have reasonable assurence that the plant level non seismic system unavailability is no more than about 0.01 [per demand]* and RCIC is cittsd as an example of t.ystems with poor non seismic failure probtbilities. For Clinton, the independent failure probability of the RCIC system used in the Individual Plant Examination (IPE), as indicated in some of the Level 1 core damago sequances (from the IPE analyses), is 0.0540 per demand, higher than that specified in EPRI NP-6041 (i.e., about 0.01). The failure probability may increase for IPEEE application because of the longer mission time required for the IPEEE (72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> for IPEEE versus 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> for i

ipr The use of generic data from NURUG 1150 for turbine-driven pumps (3E 2 per l

di d for failure to start, SE 3/ hour for failure to run, and 1E 2/ demand for un.

lability due to teu and maintenance) would yloid a higher failure probability for a 72 h,.Jr ml slon time. The reliance on RCIC alone for high pressure injection in the preferred success path is therefore questionable. To address this issue, the high pressure core spray (HPCS) system is also required in the IPEEE for some other BWR6/ Mark lll plants se a back up to the RCIC system, in these IPEEEs, although either the RCIC system or the HPCS system can satisfy the success criteria for high pressure injection, both systems are included in the safe shutdown equipment list (SSEL) for seismic evaluation. Please provide additional basis for the use of RCIC alone in the preferred success path for RCS inventory control and discuss the seismic capacity of the HPCS system.

2)

It is stated in the submittal that ' Operators use existing procedures to operate all of the systems in both of the success paths and are trained extensivdy on the use of these procedures in an on going operator training program,' but no details are provided. Since operator actions iollowing a review level earthquake (RLE) are crucial for tne successful shutdown of the plant, please discuss in more detall the types of operator actions i

needed, the locations where they have to be performed, the time available for these actions, and the estimated failure rates (e.g., obtained from IPE). Please also provide a discussion concerning the anticipated effects of the RLE on rates of operator errors which may impact the inteprity of the preferred. rid the alternate success paths, as well as a more detailed discussion of the on-going operator training program and its effect on the IPEEE.

2-Fires 1)

The heat loss factor is defined as the fraction of en6,gy re! eased 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 Fire Induced Vulnerability Evaluation (FIVE), the heat less factor le modelad as being inversely related to the amount of heat required to cause a givan temperature rise.

Thus, for example, a larger heat loss factor means that a lerge, amounMf heat (due to a more severe fire, a longer buming time,.f ooth)is needed to cruso a given temperature rise it can be seen that if the value asoumed for the heat loss factor is unrealis3cally high, fire scenarios can be improperly screened out. Figuro A.1 provides a representative example of how hot gas layer temperature predictions can change assuming different heat loss factors. Note that: 1) the curver are computed for a 1000 kW fire in a 10m x Sm x 4m compartment with a forced ventilation rate of 1130 cfm; 2) the FIVE recommended damage temperature for qualified cable is 700*F for qualified cable and 450'F for unqualifie0 cable; and 3) the curve (SFPE) in the figure is generated from a correlation provided in the Society for Fire Protection Engineers Handbook [1].

Based on evidence provided by a 1982 Daner by Cooper et al. [2], the EPRIFire FRA Implomontation Guide recommends 0 heat ioss factor of 0.94 for fires with durations greater than five minutes and 0.85 for ' exposure fires away from a wall and quickly I

developing hot gas layers.' However, bs 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 burning compartment to adjacent, cooler compartments. Earlier in the experiments, where the hot pas layer is limited to the burning compartment, Reference [2] reports 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 loss factor; and (b)large heat loss factors cannot be justified for single room scenarios based on the information referenced in the EPHI Fire PRA Implementation Gu!de.

I a

3-Time. Temperature curves 900 300

_ SFTY Y

-as H.F = 0.70

+ H.F. 0.85 E 600.

+ H.F e 0.94 g

~ x H.F= 0.7,

s 300 200

100, g x,xx.x.x,xxxixp*xxxPXX N ** # $

$b$$!hh Time (s) l Figure A.1 Sensitivity of the hot gas layer temperature predictions to the l

assumed heat loss factor For each scenario where the not gas layer temperature was calculat sd, please specify the heat loss factor value used in the analysis. In light of the preceding discucslon, 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 scerwrio contribution to core damage frequency.

References:

(1)

• SFPE Handbook of Fire Protection Engineering,' 2nd Edition, P.J. DiNenno, et al, eds., National Fire Protection Association.1995, pp. 3140.

(2)

L.Y. Cooper, M. Harkleroad, J. Quintiere, W. Rinkinen, 'An Experimental Study of Upper Hot Layer Stratification in Full Scale Multiroom Fire Scenarios,' Joumal of Heat Transfer, v. 104,7419 (November 1982).

2)

In the EPRI Fire PRA Implementation Guide, test results for th.3 control cabinet heat release rate have been misinterpreted and have been inappropriately extrapolated.

Cabinet heat release rates as low as 65 Btu /see are used in the Guide. In contrast, experimental work has developed heat release rates rangi:ig from 23 to 1171 Btu /sec.

.W

4-Consideriry the range of heat release rates that could be applicable to different control cabinet firt ; and to ensure that cabinet fire areas are not prematurely screened out of the analysis, a heat release rate in the mid range of the currently available experimental I

data (e.g.,550 Blu/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 release from a cabinet fire is increased to 550 Blu/s.

3)

The main control room (MCR) analysis employs a non suppression probability of 3.4E 3.

The use of ti.e value is equiva'ent to assurr4 g that control room operators are equally 1

l effective as optimally placed in-cabinet smoke detectors in detecting fires. Please provide additionaljustification for this assumption, including a discussion of possible MCR fire scenarios (including their locations, initial severities, ard crogression) and the effects ef control room ventilation. Also describe the fire detection system in the underfloor area and discuss the impact on detection due to the use of Tezfel cables.

4)

The submittal notes the importance of fire suppression to the plant core damage frequency (CDF) in the observation that not crediting fire suppression raises the plant CDF by a factor of 266 (Section 4.6.2). The unreliability of the suppression system is sta,ed as 2%. Such low unreliability may be reasonable for systems designed, installed, and maintained in accordance with industry standards, such as National Fire Protection Association (NFPA). It is difficult to understand the result in terms of a simple sensitiv'ty to the non suppression probability since this can account for a factor of fifty. at most, in the contribution of this scenario.

Please provide an explanation of this result that includes the modeling ascumptions used in evaluating conditional core damage

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f probabilities (CCDPs) of any sub scenarios, including their dependence i

on the non suppression probability, I

the expression used to detemilne the contribution to the CDF, the parameter values used and their justifications, such as whether the e

suppression systems were installed and maintained in accordance with industry standards, should errors be identified, a new estimate of the contribution to the CDF.

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5)

The IPEEE submittal does not address initiating events (e.g., loss-of-coolant accidents, loss of offsite power, etc.) caused by fire as a separate subject. No list is provided as to which initiating events were ana'yzed and no description is provided concoming final conclusions as to which initiating events are possible, it is also difficult to understand which system failures lead to core damage for various fire scencrios. The submittal

l b-does not explain how the event trees and faun trees were devebped/ modified for the fire CDF evaluation. Please provide the following information:

a list of initiating events that were addressed, as well as the conclusion and basis I

as to which initiating events could be caused by fire in each fire zone, l

en explanation of how the event trees and faun trees were developed and/or I

rnodified for the fire risk assessment, a listing of dominant core damage sequences in terms of areas involved,

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l system-train failures, and CDF contribution for the most significant fire scenarios.

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