ML20217J662
| ML20217J662 | |
| Person / Time | |
|---|---|
| Site: | Grand Gulf  |
| Issue date: | 10/10/1997 |
| From: | Donohew J NRC (Affiliation Not Assigned) |
| To: | Hagan J ENTERGY OPERATIONS, INC. |
| References | |
| GL-88-20, TAC-M83625, NUDOCS 9710210207 | |
| Download: ML20217J662 (9) | |
Text
Mr. Joseph J. Hagan October 10, 1997 Vice President, Operations GGNS Entergy Operations, Inc.
P. O. Box 756 Port Gibson, MS 39150
SUBJECT:
kEQUEST FOR ADDITIONAL INFORMATION RELATED TO INDIVIDUAL PLANT EXAMINATION OF EXTERNAL EVENTS, GRAND GULF NUCLEAR STATION, UNIT 1 (TAC NO. M83625)
Dear Mr. Hagan:
The staff is reviewing your submittals dated December 20, 1991, June 16 and December 20, 1994, and March 1 and hovember 15, 199E (GNR0-91/00198, 94/00089, 94/00148, 95/00026, and 95/00122) on the Individual Plant Examination of External Events (IPEEE), Generic Letter 88-20, Supplements 4 and 5, dated June 28, 1991, and September 8, 1995, respectively.
Based on this review, the enclosed request for additional information (RAI) has been developed. The RAI is related to the fire risk analyses in the IPEEE. To continue our review on our current schedule, we request that the information in the RAI be provided within 60 days of your receipt of this letter.
- ncerely, ti ew, Senior Project Manager h
Project Dire:.torate IV-1 Division of Reactor Projects III/IV Office of Nuclear Reactor Regulation Docket No. 50-416
Enclosure:
Request for Additional Information cc w/ encl:
See next_page DISTRIBUTION:
Docket 1F11e rf PUBLIC PD4-1 r/f J. Clifford
'ET Aderisain (EGAl)
J. Donohew C. Hawes E. Chelliah P. Gwynn, RIV ACRS OGC (15B18)
M. Cunningham Document Name:
GG83625.RAI 0FC PM/Pp(Q LA/PD4-1 ok NAME JDkN/vw CHawes C#1N N
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NUCLEAR RECULATORY COMM1881CN WASHINeTON. D.C. asseMeM 4
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October 10,1997 I
1 I
Mr. Joseph J. Hagan I
Vice President, Operations GGNS 4
Entergy Operations, Inc.
P. O. Box 756 Port Gibson, MS 39150
SUBJECT:
REQUEST FOR ADDITIONAL INFORMATION RELATED TO INDIVIDUAL PLANT l
EXAMINATION OF EXTERNAL EVENTS, GRAND GULF NUCLEAR STATION, UNIT 1
~
(TAC NO. M83625) i
Dear Mr. Hagan:
The staff is reviewing your submittals dated December 20, 1991, June 16 l
and December 20, 1994, and harch I and November 15, 1995 (GNRO-91/00198, f
94/00089, 94/00148, 95/00026, and 95/00122) on the Individual Plant.
1 Examination of External Events (IPEEE), Generic Letter 88-20, Supplements 4 and 5, dated June 28, 1991, and Sept 6mber 8,1995, respectively. Based on this review, the enclosed request for additional information (RAI) has been i
developed. The RAI is related to the fire risk analyses in thu IPEEE. To l
i continue our review on our current schedule, we request that the information in the RAI be provided within 60 days of your receipt of this letter.
Sincerely, Jack N. Donohew, nior Project Manager Preject Directorate IV Division of Reactor Projects III/IV-Office of Nuclear Reactor Regulation Docket No. 50-416
Enclosure:
Rsquest for Additional Information ccw/ encl: See next page i
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Mr. Joseph J. Hagan Entergy Operations, Inc.
Grand Gulf Nuclear Station i
cc:
Executive Vice President General Manager, GGNS
& Chief Operating Officer Entergy Operations, Inc.
1 Entergy Operations, Inc.
P. O. Box 756 P. O. Box 31995 Port Gibson, MS - 39150 Jackson, MS 3928G-1995 Attorney General Wise, Carter, Child & Caraway Department of Justice P. O. Box 651 State of Louisiana Jackson, MS 39205 P. O. Box 94005 Bston Rouge, LA 70804-9005 Winston & Strawn 1400 L Street, N.W. - 12th Floor State Health Officer Washington, DC 20005-3502 Stste Board of Health P. O. Box 1700 Director Jackson, MS 39205 Division of Solid Waste Management Mississippi Department of Natural Office of the Governor Resources State of Mississippi P. O. Cox 10385 Jackson, MS 39201 Jackson, MS 39209 Attorney General Presidert, Asst. Attorney General claiborne County Board of Supervisors State of Mississippi P. O. Box 339 P. O. Box 22947 Port Gibson, MS 39150 Jackson, MS 39225 Regional Administrator, Region IV Vice President, Operations Support U.S. Nuclear Regulatory Commission Entergy Operations, Inc.
611 Ryan Plaza Drive, Suite 2000 P.O. Box 31995 Arlington, TX 76011 Jackson, MS 39286-1995 Senior Resident Inspector Director, Nuclear Safety U. S. N:: lear Regulatory Commission and Regulatory Affairs Route 2, Box 399 Entergy Operations, Inc.
Port Gibson, MS 39150 P.O. Box 756 Port Gibson, MS 39150 Manager of Operations Bechtel Power Corporation P.O. Box 2166 Houston, TX 77252-2166 1
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REQUEST FOR ADDITIONAL INFORMATION RELATED TO INDIVIDUAL PLANT EXAMINATION OF EXTERNAL EVENTS flPEEE)-
FIRE RISK ANALYSES IN THE IPEEE ENTERGY OPERATIONS. INC.
GRAND GULF NUCLEAR STATION DOCKET N0. 50-416 The following request for additional information is concerned with the licensee's submittals dated December 20. 1991, June 16 and Dscomber 20, 1994, and March I and November 15, 1995, on the Individual-Plant Examination of External Events IPEEE), Generic Letter 88-20, Supplements 4 and 5, dated an(d September 8,1995, respectively, for Grand Gulf Nuclear June 28, 1991, Station, Unit 1 (GGNS). The request for additional information (RAI) was developed by the Nuclear Regulatory Comission's (NRC's) contractor, Sandia National Laboratories, and reviewed by the Senior Review Board for the IPEEE.
FIRE EVENTS:
1.
It is important that the human error probabilities (HEPs) used in the screening phase-of the analysis properly reflect the potential effects of fire (e.g., smoke, heat, loss of lighting), even if these effects do not directly cause equipment damage in the scenarios being analyzed.
If these effects are not treated, the HEPs may be optimistic and result in the improper screening of scenarios. Note that HEPs which are conservative with respect to an internal events analysis could be non-conservative with respect to a fire risk analysis.
Identify the following:
(1) the scenarios screened out from further analysis whose quantification involved one or more HEPs, (2)ios, and (3) the HEPs (descriptions and numerical valvas) for each of these scenar how the effects of the postulated fires were treated.
A reanalysis may be requested if performance shaping factors (PSFs) besides stress associated with fires (e.g., smoke, loss of lighting, poor communication) are relevant and have not been considered.
2.
From the submittal dated November 15, 1995, it can be inferred that the licensee has not considered hot shorts as a failure mode for control and instrumentation cables.
In particular, hot short considerations should include the treatment of conductor-to-conductor shorts within a given cable. Hot shorts in control cables can simulate the closing of control switches leading, for example, to the repositioning of valves, spurious operation of motors and pumps, or the shutdown of operating equipment.
ENCLOSURE 4*
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These types of f4ults might, for example, lead to a loss-of-coolant accident (LOCA), diversion of flow within various plant systems, deadheading and failure of important pumps, premature or undesirable-switching of pump suction sources, or undesirable equi > ment operations.
For main control room (MCR) abandonment scenarios, suci spurious operations and actions may not be indicated at the remote shutdown panel (s) (RSPs), may not be directly recoverable from remote shutdown locations, or may lead to the loss of remote rhutdown capability (hot e.g.,
through loss of RSP power sources).
In instrumentation circuits, shorts may cause misleading plant readings potentially leading to inappropriate control actions or generat' on of actuation signals for emergency safeguard features.
Discuss to what extend the above issues have been considered in the IPEEE for GGNS.
If they have not been considered, provide an assessment of how inclusion of potential hot shorts would impact the quantification of fire risk scenarios in the IPEEE.
3.
The screening process resulted in 13 unscreened compartments requiring detailed analysis.
In your submittal of November 15, 1995, detailed modeling of 6 of the 13 unscreened compartments was submitted. Provide l
information on the remaining 7 unscreened compartments not discussed in the submittal. Specifically, the 7 compartments are the following:
i Division 2 Switchgear Room Turbine Building, 93' elevation Lower Cable Room, 148' elevation Hot Machine Shop, 93' elevation Division 3 High Pressure Core Spray Diesel Generator Building Heating Ventilation and Air Conditioning (HVAC) Equipment Room, 133' elevation Turbine Building, 113' elevation 4.
In the Electric Power Research Institute (EPRI) Fire Probabilistic Risk Assessment (PRA) Implementation Guide, test results for the control cabinet heat release rate have been misinterpreted and have been inappropriately extrasolated. Cabinet heat release ratcs as low as 65 Btu /sec are used in tte Guide.
In contrast, experimental work has-developed heat release rates ranging from 23 to 1171 Btu /sec, Considering the range of heat release rates that could be applicable to different control cabinet fires, 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 data (e.g., 550 Btu /sec) should be used for the analysis.
Discuss the heat release rates used in the 1PEEE assessment of control cabinet fires for GGNS. Provide a discussion of changes in the IPEEE fire assessment results if the heat release from a cabinet fire is increased to 550 Btu /sec.
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The EPRI Fire PRA Implementation Guide methodology for evaluating the effectiveness of suppression efforts treats manual recovery of automatic suppression systems as being indepandent of subsequent manual efforts to suppress the fire. This assumption is optimistic, as the fire conditions (e.g., heat and smoke) that lead to the failure of recovery offorts can also influence the effectivene:s of later suppression efforts.
Such an approach, therefore, can overlook plant-specific vulnerabilities.
It is important that all relevant factors be considered in an evaluation of the effectiveness of fire suppression. These factors include:
the delay between ignition and detector / suppression system actuation (which is specific to the configuration being analyzed),
the time-to-damage for the critical component (s) (which is specific e
to fuel type and loading as well as to the configuration being modelled),
the response time of the fire brigade (which'is plant-specific and fire-location specific) the time required by the fire brigade to diagnose that autometic suppression has failed and to take manual action to recover the automatic suppression system, and PSFs, such as perseverance (persistent efforts made to recover a failed automatic suppression system), smoke obscuration, and impaired communications (Reference 1), affecting fire brigade actions.
Finally, it should be noted that the NRC staff's eval'uation of the fire-induced vulnerability evaluation (FIVE) methodology (Reference 2) specifically stated that licensees need to assess the effectiveness of manual fire-fighting teams by using plant-specific data from fire brigade training tt-determine the response time of the fire ff-hters.
Identify and discuss those scenarios for which credit is taken for both manual recovery of automatic fire suppression systems and manual suppression of the fires (if manual recovery efforts are unsuccessful),
and indicate the plant equipment that may be affected by the fires.
In the analysis of these scenarios, discuss how dependencies between manual
. actions are treated. Justify the treatment, considering the expected-fire environment,'the recovery actions required, and the manual fire suppression actions required.
6.
.The heat' loss factor is defined as the fraction of energy released by a
- fire that is transferred to the enclosure boundaries. "his 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 FIVE, the heat loss factor is modeled as being inversely related to the amount of heat required 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 longer burning time, or both) is needed to cause a given OT OS-w mhwwwiyg M
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It can'be seen that if the value assumed for the heat r
loss factor is unrealistically high, fire scenarios can be improperly i
screened out.
Figure 1 provides a representative example of how hot gas i
layer temperature predictions can chanqe assuming different heat loss factors. Note the following:
3 i
the curves are computed for a 1000 kW fire in a 10m x 5m x 4e compartment with a forced ventilation rate of 1130 cfs, the FIVE-recommended damage temperature for cable is 700 'F for i
qualified cable and 450 'F for un-qualified cable, the time-temperature curve in figure 1 is generated from a orrelation provided in the Society for Fire Protection Engineers j
(SFPE) Handbook (Reference 3).
}
Based on the evidence provided by a 1982 pa>er (Reference 4), the EPRI Fire PRA Implementation Guide recommends a 1 eat loss factor of 0.94-for fires with durations greater than 5 minutes and 0.85 for " exposure fires i
away from a wall and quickly developing hot gas layers." However, as a general statement, this appears to be a misinterpretation of the results.
Reference 4, which documents the results of multi-compartment fire l
experiments, states that the higher heat loss factors kre associated with l
the movement of the hot gas layer from the burning compartment to
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adjacent, cooler compartments. Earlier in the experiments, where the hot j
gas layer is limited to the burning compartment, Reference 4 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, hot gas layer predictions are very sensitive to the 3
assumed value of the heat loss factor, and large heat loss factors cannot be justified for single-room scenarios based on the information referenced in the EPRI Fire PRA Implementation Guide, j
f Specify and discuss, for each scenario where the hot gas layer i
temperature was calculated, the heat loss factor value used in the
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analysis.
In light of the preceding discussion, either (1) justify the value used and discuss its effect on the identification of 1.re i
vulnerabilities, or (2) repeat the analysis using a more justifiable i~
value and provide the resulting change in scenario contribution to the j
core damage frequency.
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7.
The failure probability for automatic fire suppression in the submittal used the FIVE values. These values are acceptable for systems that have i
been designed, installed, and maintained in accordance with appropriate industry standards, such as those published by the National Fire 4
Protection Agency (NFPA). Verify that automatic suppression systems at j
i 8.'
The GGNS IPEEE submittal indicates a failure probability of manual suppression, in 45 minutes, for Thermo-l.ag protected cables is 0.15.
It r
is generally observed that there is no established relation between the e
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Provide the basis, including the docuinented references, for the IPEEE assignment of 0.15 for manual suppression failure probability.
j.
Also, discuss the impact of taking no credit for Thermo-Lag protected cables on the overall core damage frequency.
9.
All exposure fires are assumed to be detected and suppressed in 15 minutes. This assumption may not be realistic depending on the availability of detection and suppression in the area and in light of the fact that a fire severity factor was used.
Provide an alternate analysis for the 13 areas that survived screening that 1 includes consideration of the area-specific features of detection and(su)ppression, the thing of f
detection and suppression, and the likelihood that suppression may fail, and (2) is consistent with the assumption of a fire severity factor.
10.
From the discussions provided (e.g., page 91, Section 4.6.4.3) in the submittal of November 15, 1995, for multi-compartment fire scenarios, it is not clear whether it is assumed that fire doors, dampers, and other active fire barriers are in the open position.
It is also not clear from the submittal if high hazard areas such as the turbine building, diesel generator room, switchgear rooms, and lube oil stora e areas were 4
appropriately considered. The Unit 2 compartments with high combustible loadings should be considered in multi-compartment fire scenarios.
Discuss the treatment of open barrier elements, high hazard areas, and j
Unit 2 fires in the multi-compartment analysis for Unit 1.
i
REFERENCES:
1.
J. Lambright, et. al., "A Review of Fire PRA Requantification Studies Reported in NSA/181 " prepared for the United States Nuclear Regulatory Commission, April 1994.
4 2.
A. Thadani, "NRC Staff Evaluation Report on Revised NUMARC/EPRI Fire Vulnerability Evaluation (FIVE) Methodology," U.S. Nuclear Regulatory 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").
3.
P.J. DiNenno, et. al., eds., "SFPE Handbook of Fire Protection Engineering,* 2nd Edition, National Fire Protection Association,
- p. 3-140, 1995.
4.
L Y. Cooper, M. Harkleroad, J. Quintiere, W. Rinkinen, "An Experimental Study of Upper Hot Layer Stratification in Full-Scale Multiroom Fire Scenarios," ASME Journal of Heat Transfer, 104, 741-749, November 1982.
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