ML20092N328
| ML20092N328 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 10/02/1995 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20092N329 | List: |
| References | |
| NUDOCS 9510050264 | |
| Download: ML20092N328 (3) | |
Text
.. _
\\
4 PdANTShSTEMS i
JASES t
l Q
Nominal NSSS power rating of the plant (including reactor
=
coolant pump heat), Mwt i
Conversion factor, 947.82 (8tu/sec)
K Mwt h
w, Minimum total steam flow rate capability of the operable MSSVs on any one steam generator at the highest MSSV opening pressure including tolerance and accumulation, as appropriate, in 1b/sec.
For example, if the maximum number of inoperable MSSVs on any 1
one steam generator is one, then w should be a summation of the i
capacity of the operable MSSVs at the highest operable MSSV j
operating pressure, excluding the highest capacity MSSV.
If the maximum number of inoperable MSSVs per steam generator is three then w should be a summation of the capacity of the operable i
MSSVs at the highest operable MSSV operating pressure, excluding the three highest capacity MSSVs.
heat of vaporization for steam at the highest MSSV opening h
3 j
pressure including tolerance and accumulation, as appropriate, l
Btu /lba j
N Number of loops in plant The values calculated from this algorithm must then be adjusted lower to l
account for instrument and channel uncertainties.
3/4.7.1.2 AUXILIARY FEEDWATER SYSTEM l
l The AFW System is configured into three trains. The AFW System is 4
considered OPERABLE when the components and flow paths required to provide redundant AFW flow to the steam generators are OPERABLE. This requires that the l
two motor-driven AFW pumps be OPERABLE in two diverse paths, each supplying AFW i
to separate steam generators. The turbine-driven AFW pump is requirod to be OPERABLE with redundant steam supplies from each of two main steam lines i
upstream of the MSIV's, and shall be capable of supplying AFW to any steam generttor. The piping, valves, instrumentation, and controls in the required flow paths also are required to be OPERABLE.
T l
The AFW System mitigates the consequences of any event with loss of normal l
The design basis of the AFW System is to supply water to the steam generator to remove decay heat and other residual heat by delivering at least the minimum required flow rate to the steam generators at a pressure corresponding to 1085 psig. This pressure is in excess of the maximum expected steam generator pressure with the existing safety valve setpoints.
In addition, the AFW System must supply enough makeup water to replace steam generator secondary inventory lost as the unit cools to MODE 4 conditions. Sufficient AFW flow must also be available to account for flow l
losses such as pump recirculation and line breaks.
]
i 9510050264 951004 PDR ADOCK 05000327 l
P PDR SEQUOYAH - UNIT 2 B 3/4 7-2 Amendment No. 105, 187, 196 4
--e r-v
l 1
(
PL'ANTSlSTEMS BASES The limiting Design Basis Accidents (DBAs) and transients for the AFW System are as follows:
a.
Feedwater Line Break (FWLB); and b.
In addition, the minimum available AFW flow and system characteristics are credited for removing decay heat in the analysis of a small break loss of coolant accident (LOCA).
The AFW System design is such that it can perform its function following a FWLB between the MFW isolation valves and containment, combined with a loss of offsite power following turbine trip, and a single active failure of the steam turbine-driven AFW pump (above 50% power) or one motor-driven AFW pump (below 50% power with steam generator low level reactor trip time delay). For 50%
power operation and higher, one motor-driven AFW pump is assumed to deliver to the broken MFW header at the pump run-out flow. Sufficient flow would be delivered to the intact steam generator by the redundant motor-driven AFW pump.
For partial power operation (below 50% power with trip time delay active),
one motor-driven AFW pump is assumed to fail. All flow from the turbine-driven AFW pump and the redundant motor-driven AFW pump is assumed to deliver to the broken MFW header until the faulted steam generator is isolated by operator action 10 minutes after the break. After isolation of the faulted steam 4
j generator, sufficient flow is delivered to the intact steam generator by the turbine-driven and redundant motor-driven AFW pump.
4 The Engineered Safety Feature Actuation System (ESFAS) automatically l
actuates the AFW turbine-driven pump and associated valves and controls when required to ensure an adequate feedwater supply to the steam generators during loss of power.
The surveillance requirements (SRs) provide a means of ensuring the AFW system components are capable of supplying required flow to the steam generators, the flow path is aligned correctly, and the automatic functions actuate as designed. The automatic functions are verified through either an l
actual or simulated actuation signal. The actuation signal associated with SR 4.7.1.2.3 (automatic valve actuation) include the AFW actuation test signal and j
the low AFW pump suction pressure test signal. The actuation signal associated with SR 4.7.1.2.4 (automatic pump start) includes only the AFW actuation test j
signal.
Each motor-driven auxiliary feedwater pump (one Train A and one Train B) supplies flow paths to two steam generators.
Each flow path contains an auto-l matic air-operated level control valve (LCV). The LCVs have the same train designation as the associated pump and are provided trained air.
The turbine-driven auxiliary feedwater pump supplies flow paths to all four steam genera-tors.
Each of these flow paths contains an automatic opening (non-modulating) air-operated LCV, two of which are designated as Train A, receive A-train air, and provide flow to the same steam generators that are supplied by the B-train motor-driven auxiliary feedwater pump. The remaining two LCVs are designated as Train B, receive B-SEQUOYAH - UNIT 2 B 3/4 7-2a Amendment No. 196
}
}
t
\\
Mr. Oliver D. Kingsley, Jr.
SEQUOYAH NUCLEAR PLANT Tennessee Valley Authority cc:
Mr. O. J. Zeringue, Sr. Vice President TVA Representative Nuclear Operations Tennessee Valley Authority Tennessee Valley Authority 11921 Rockville Pike 3B Lookout Place Suite 402 1101 Market Street Rockville, MD 20852 Chattanooga, TN 37402-2801 Regional Administrator Dr. Mark 0. Medford, Vice President U.S. Nuclear Regulatory Commission Engineering & Technical Services Region II Tennessee Valley Authority 101 Marietta Street, NW., Suite 2900 3B Lookout Place Atlanta, GA 30323 1101 Market Street Chattanooga, TN 37402-2801 Mr. William E. Holland Senior Resident Inspector Mr. D. E. Nunn, Vice President Sequoyah Nuclear Plant New Plant Completion U.S. Nuclear Regulatory Commission Tennessee Valley Authority 2600 Igou Ferry Road 38 Lookout Place Soddy Daisy, TN 37379 1101 Market Street Chattanooga, TN 37402-2801 Mr. Michael H. Mobley, Director Division of Radiological Health Mr. R. J. Adney, Site Vice President 3rd Floor, L and C Annex Sequoyah Nuclear Plant 401 Church Street Tennessee Valley Authority Nashville, TN 37243-1532 l
P.O. Box 2000 1
Soddy Daisy, TN 37379 County Judge Hamilton County Courthouse General Counsel Chattanooga, TN 37402-2801 Tennessee Valley Authority ET llH 400 West Summit Hill Drive Knoxville, TN 37902 Mr. P. P. Carier, Manager Corporjte Licensing 4
Tennessee Valley Authority 4G Blue Ridge 1101 Market Street Chattanooga, TN 37402-2801 Mr. Ralph H. Shell Site Licensing Manager Sequoyah Nuclear Plant Tennessee Valley Authority P.O Box 2000 Soddy Daisy, TN 37379 m
.