ML20086E257
| ML20086E257 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 11/22/1991 |
| From: | William Cahill, Woodlan D TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| TXX-91426, NUDOCS 9111270134 | |
| Download: ML20086E257 (10) | |
Text
1 l
lllllllll" Log # TXX-91426 1.
File # 10010 (clo) 908.3 Ref. # 10CFR50.63 TUELECTRIC November 22, 1991 Wul%m J. Cahill, Jr.
Group M twiJnr U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C.
20555
SUBJECT:
COMANCHE PEAK STEAM ELECTRIC STATION (CPSES) UNIT 1 DOCKET N0. 50-445 RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION RE:
CPSES STATION BLACKOUT SUBHITTAL - UNIT 1 REF:
- 1) TU Electric letter logged TXX-901008, from William J. Cahill, Jr. to the NRC, dated November b. 1990
- 2) NRC letter from T. A. Bergman to William J. Cahill, Jr.
dated October 22, 1991 Gentlemen:
In Reference 1. TU Electric submitted to the NRC, the CPSES Station Blackout (5B0) submittal pursuant to 10CFR50.63, " Loss of All Alternating Current Power." Attachment 1 is TV Electric's response to the NRC's request for additional information regarding the CPSES SB0 submittal, as identified in Reference 2.
In an attempt to expedite the NRC review process, a conference call was held on November 1, 1991, between TU Electric and the NRC to discuss, in advance of the RAI submittal, TU clectric's response to Questhons I through 4.
The responses given during the conference call are also documented in to this letter.
Supporting documenta+. ion is available an site l
for review.
If there are any questions, contact Veronica Cornell at (214) 812-8886.
l l
Sincerelv.
l Willia. J. Cahill, Jr.
By:
D. R. Wooditn Docket Licensing Manager VPC/gj Attachment
}
j c - Mr. R. D. Hartin, Region IV T)
Resident inspectors, CPSES (2) l Hr. T. A. Bergman. NRR
}
{
/" 7 hhhhbfr b
I 43 p
Attachment I to TXX-91426 Page 1 of 7 QUESTIONS ON COMANCHE PEAK STATION BLACK 0UT SUBMITTAL NRC Question 1:
Battery Calculations State the assumptions (i.e., temperature factor, design margin, aging factor) used to determine that the battery capacity is adequate for four hours.
In addition, address whether or not the battery capacity calculations take into account the additional capacity which will required to operate the DC powered ventilation fans for the uninterruptible power supply (UPS) inverter rooms (proposed station blackout (SBO) modification).
The Final Safety Analysis Report shows a battery load profile for four hours which we consider to bound the SB0 loads.
TV Electric Response 1: Battery Calculations The following assumptions / conditions were used to determine the battery c6pacity for SB0.
- a. Minimum electrolytic temperature of 65 degrees F, based on the SB0 calculated minimum temperature of 67 degrees F (reference calculation ME-CA-0305-3027 Revision 0),
- b. Battery sizing in accordance with IEEE 485,
- c. Aging factor of 1.25 based on IEEE 485,
- d. Temperature correction factor of 1.08 based on IEEE 485,
- e. Design margins of 25 and 35 percent for the Class 1E batteries based on the 580 analysis, and
- f. No load shedding assumed, i
l Currently, there are no plans to operate the proposed DC power fan motors on the safety-related buses. A new or existing non-safety battery will be used as part of that design modification.
No credit is taken for load shedding, therefore the SB0 loads are bounded by the FSAR loads,
Reference:
Calculation 16345-EE(B)-053 Revision 5 with supplemental Calculation EE-CA-0009-3025 Revision 0 " Station Blackout Class 1E Battery Canacity" l
1
. to TXX-91426
.Page 2 of 7 NRC Question 2:
Compressed Air i
-It is our understanding that t.a auxiliary feedwater (AFW) thrcttling valves will ba operated manually to control AFW flow after the air acccmulators have been depleted during a 5B0.
Explain how the issue of habitability (environment, communication, lighting, etc.) has been addressed for the local operation of these valves.
We agree with the discussion in your November 5, 1990, submittal which indicates that the atmospheric relief valve (ARV)' accumulators are sized to provide sufficient air for four hears of valve operation during.a 5B0.
Describe the location from which these valves will be operated during a SB0 and verify that it is habitable.
TU Electric Response 2:
Compressed Air In the event of an SB0, operation of the AFW throttling valves will be performed locally with direct communicat.ons with the Control Room.
The method of communication is l
_ portable radios.
Adequate lighting in the ;rea is provided by Fire Safe Sh'itdown battery powered lights.
The power source to these lights is expected to be available in excess of the four hour coping analysis requirement.
Accessibility and habitability of the turbire driven auxiliary feedwater pump room were evaluated based on the expected amb1ent temperature conditions, The bricf intervals of exposure to temperatures in this area will not prevent the operators from performing the valve manipulations within the room.
The ARVs can be operated from the control room.
The control room is a Condition 1 area.
It has been determined that habitability a-d equipment operability in the control room is preserved.
l NRC Question 3:
SB0 Equ.p.nent Quality Assurance Program Verify that all equipment needed to cope with a SB0 event meets the provisions of RG 1.155, " Station Blackout."
I Regulatory Position 3.5.
TV Electric Response 3:
SB0 Equipment Quality Assurance Program Equipment required to cope with an SB0 is safety related and included in the CPSES 0A program, pursuant 10CFR50, Appendix l
B, except for the turbine stop vr.lves.
In the SB0 scent-10, l
l
. to TXX-91426 Page 3 of 7 the turbine stop valves are relied upon for immediate steam isolation.
These valves are non-safety related, but are surveilled and maintained per CPSES Technical Specification 3/4.3.4, " Turbine Overspeed Protection."
NRC Question 4?
Reactor Coolant Inventory Provide a summary of the CPSES-specific reactor coolant system (RCS) inventory analysis, including the RCS leak rates used, the initial and final RCS water volume and temperature, the amount of water raquired to cover the core, and any other key parameters and assumptions used in the calculation.
TU Electric Response 4:
Reactor Coolant Inventory The CPSES RCS inventory calculation was performed in two segments.
The initial scgment, from event initiation up to L
2900 seconds into the event, was analyzed using the RETRAN-0?
transient analysis code and a two-loop model of the RCS.
The code was used for this segment of the event to accurately account for the numerous perturbations which occur in the system (e.g., reactor trip, RCf coastdown, AfW initiation, p
RCS depressurization).
The second segment, from 2900 seconds until projected core uncovery, was analyzed by a hand calcolation.
This is possible during this segment of tne event because the system is relatively stable with no major perturbations occurring.
The RETRAN-02 analysis included models for RCS leakage (as a function of RCS pressure) and for operator actions such as AI.V actuation to depressurize the RCS and AFW control to maintain steam generator level.
The RCS leakage was based on the following:
- 1. Normal system leakage as specified in Technical Specification 3.4.5.2.
This consists of I gpm unidenti fied leakage, 1 gpm primary-to-secondary leakage, and 10 gpm unidentified Icakage.
- 4. All RC5 leakage is a function of PLS pressure and will decrease as RLS pressure decreases.
(RCS pressure remained above the accumulator injection pressure.)
Othei assumptions included in the analysis were consistent with those in Section 2.4 of NUMARC 87-00.
)
' to TXX-91426 Page 4 of 7 The RETRAN-02 portion of the analysis determined the RCS mass inventory, pressure, and leakage rate up through 2900 seconds.
At this point in the event, the system response was relatively stable, The RETRAN-02 results for mass inventory and leakage rate could then be used to determine the remaining time to core uncovery.
As long as the total time to core uncovery was greater than the 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> coping duration requirement for the SBO, then the acceptance criterion was considered to be met.
Since the analysis was performed in this manner, the final RCS inventory and temperature at the 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> point were not calculated since it was concluded that core would remain covered in excess of 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />.
NRC Ouestion 5:
Loss of Heating, Ventilating, and Air Conditioning (HVAC)
Systems More detailed explanations of the effects of loss of ventilation are needed in order to perform a meaningful review.
Please provide the calculation package (s) so that we can expediently and completely perform our review.
Our
. initial concerns are:
(a)
Ex,1ain the CPSES-specific method that was used to calculate the temperature rises.
(b)
State the major assumptions used in each room analysis (i.e., heat loads, initial temperatures, inverter efficiency, material nroperties, timing).
(c)
Identify any rooms in which the corridor doors and/or designated cabinets need to be opened.
Identify the procedure which governs this action.
(d)
The generic Westinghouse calculation of the temperature response inside containment which was refer-ed to in your November 5. 1990 submittal has not been reviewed by the NRC.
Verify that the expected temperature inside containment during a SP0 event are enveloped by the loss-of-coolant accident and high-energy line break temperature profiles.
Attachment I to TXX-91426 Page 5 of 7 TU Electric Response 5:
Loss of Heating, Ventilating, and Air Conditioning (HVAC) Systems (a) CPS 15 HETH02 The Systems Improved Numerical Differencing Analyzer (SINDA) computer code was used for all room analyses except for containment where CONTEMPT-L126 was used, SINDA is a software system which possesses capabilities which makt it well suited for solving lumped parameter representations of physical problems governed by diffusion-type equations.
The system is designed as a general analyzer accepting conductor-capacitor (G-C) network representations of thermal systems.
SINDA can solve other types of problems that can be represented as G-C networks.
A conductor-capacitor network can be described as a system which allows heat to be cransferred thrcuph various paths with different material properties, where the thermo1 conductivity of these materials act as resistances to the heat transfer process and the thermal capacity of each material acts as thermal storage. This type modeling allows one to predict a thermal transient using structures as heat sinks and heat ccnductors. Thus, the individual areas in the plant can be modeled as they interact with each other.
CONTEMPT-LT is a computer program developed to describe the thermal-hydraulic behavior of reactor containment systems subjected to postulated accident conditions.
CONfEMPT-LT provides a numerical method for analyzing the transient containment behavior of pressurized water reactors, boiling water reactors (Mark 1. Mark !!, or Mark III), and exoerimental water reactor simulators or related experiments. CONTEMPT-LT predicts the interrelated effects of reactor system blowdown, heat transfer, atmosphere leakage, safeguard system operation, pressure suppression system response, and miscellaneous mass and energy additions.
Both codes determine temperatures as a function of room volumes and how they interact with other rooms, concrete, metal, and natural convection airflow.
Analyses are organized by building / room and also take into account the affect of the temperature outdoors ad l
it varies diurnally.
Heat addition from electrical j
equipment, methonical e mipment piping, and ilghting where applicable, was considered and quantified for each room.
8 Attachment I to TXX-91426
.Page 6 of 7 (b) tiA)0R AS1VMPTIONS AC powered' electrical cables associated with the emergency diesel generators were considered to be energized. This is conservative since during an 590, these cables would not be energized.
Piping heat loads were based on the most conservative modes of operation such as a LOCA in one unit with the other unit in cooldown.
This is very conservative since most of these heat sources (e.g., residual heat removal, containment spray, component cooling water) would not be in operation during an SBO, The maximum room design temperatures (104, 120, and 122 degrees F as stated in Table 9,4-2 of the FSAR) for l
CPSES were used for the initial conditions except for l
control room.
These initial temperatures are based on l
110 degrees F outside air and equipmeat operating prior l
to an SB0 with an ultimata heat sink temperature of 102 degrees F.
Analyses showed that the peak temperatures occurred for beyond the 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> assumed for the SB0 event except in the case of the Uninterruptible Power Supply rooms.
In the control room analysis, the following applied:
- an initial temperature of 80 degrees F (maximum normal temperature per FSAR Table 9,4-2),
- surrounding outside temperatures of 193 degrees F (black roof), 125 degrees F, and 120 degrees F.
- surrounding concrete used as heat sinks (free flow l
of air through tie false ceiling that has an 5 inch " shake space" around the perimeter and " egg crate" material over the horseshoe area).
l
- no credit taken for the heat sink capacity of the j
massive metal seismic ceiling supports.
- no mechanical equipmer t or riping heat added.
UPS Rooms:
I
- Inverter efficiencies were 77% for the
.5KVA units and 86% for the 10KVA units.
1
Attachment I to TXX 91426 i
l' age 7 of-7 Containment
- heat addition rate of SE6 Btu /hr from piping and equipment.
- initial temperature was 120 degrees F.
- thermal cunductivities (BTU /hr-ft-F) - steel-26, concrete.854.
- decay heat and seal leakage was determine to be unnecessary based on the attached curves which show the 500 and LOCA/HSLB temperature and pressure profiles.
Material Properties:
- See Attachment 2 which shows excerpt from Calculation 3 0-2 #08 Revision O.
(c)
In the CPSES SB0. analysis, credit is taken for opening doors and/or cabinets in the control room, battery charger and inverter rooms to mitigate the effects of internal heating of. electrical equipment, Procedure ABN-601, " Response to a 148/345kV System Halfunction,"
governs these actions.
(d)
See the incontainment temperature curve in Attachment 3.
l l
-. ~...
-l
, to TXX-91426 Page-1 of.1 l
MATERIAL PROPERTIES TO BE USED IN 'SINDA' INPUT l
l p
Cp k
pCp 3
3 HATERIAL (ibm /ft )
Btu /lbm OF Btu /hr-ft OF)
Btu /ft 0F)
I
- 1. CONCRETE 145 0.156 0.92 22.62 l
- 2. PIPE WALL 463 0.093 39 43.06 I
I i
- 3. INSULATION 3.33 0.2 0.0233 0.666 (Al-A3) i
- 4. INSULATION 13' O.2 0.0367 2.6 (D1-06)
- 5. RIGID 15 0.17 0.024-2.55 INSULATION l
(ROOF) i
- 6. STEEL 463 0.093 8.7 43.06 (ROOF)
- 7. GYPSUH/
90 0.2 0.28 18.0 1
PLASTER (PARTITION)
- 8. S0ll 103 0.22 0.532 22.66
- 9. DIESEL 51.8 0.54 0.077 27.97 Oil l
l l
l
1 l
I to TXX-91426 Page 1 of 1 l EMPERATURE (deg Q U
A d'
8 8
b I
O I
~
o e
e o
e e
o e
e o
i
.2 i
i i
i i
nA e4 f
O O
o Z
a M
n y
I Z
I h
m C3 y
Z e
m a
i 9
o M
- g 9-f g
O M
m
)$
.p N
t
_o r
m r-1 o
o e
m M
i i
a
- -