ML18079A322
| ML18079A322 | |
| Person / Time | |
|---|---|
| Site: | Salem  |
| Issue date: | 05/17/1979 |
| From: | Mittl R Public Service Enterprise Group |
| To: | Parr O Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 7905250100 | |
| Download: ML18079A322 (4) | |
Text
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Public Service Electric and Gas Company 80 Park Place Newar!<. N.J 07101 PhoriG 201 430 7()(J()
May l7, 1979 Director of Nuclear Reactor Regulation U. s. Nuclear Regulatory Commission Washington, D. C.
20555 Attention:
Gentlemen:
Mr. Olan D. Parr, Chief Light Water Reactors Branch 3 Division of Project Management RESPONSE TO REQUESTS FOR ADDITIONAL INFORMATION NO. 2 UNIT SALEM NUCLEAR GENERATING STATION DOCKET NO. 50-311 Public Service Electric & Gas Company hereby transmits sixty (60) copies of its response to your request for additional information regarding the NPSH available for the RHR pumps during the accident recovery recirculation mode.
Should you have any questions, please do not hesitate to contact us.
Enclosure
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'l (,/. I L-1 R. L. Mittl General Manager -
Licensing and Environment Engineering and Construction 7905250(00 *f (3H>' J s 'II
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NPSH REQUIREMENTS FOR RHR PUMPS DURING RECIRCULATION MODE During a telephone conversation the NRC had requested an evaluation to indicate that the NPSH available for RHR pumps during the accident recovery recirculation mode is sufficient for the worst possible flow configurations.
The following address the NRC's concerns:
- 1.
The RHR pump performance is evaluated for the configu-ration which would result in the highest RHR flow, i.e., one RHR pump feeding two charging pumps, two safety injection pumps and also directly into two cold legs.
This evaluation is done in two parts.
a)
Establish the maximum flow rate for the RHR pump for the flow configuration described using field test data and pump characteristics.
b)
Evaluate the NPSH for the RHR pump when the pump suction is from the containment sump for a flow rate greater than the maximum established (para l.a) and assuming 50% blockage of the sump screen, RWST emptied to the level when the recirculation mode is initiated.
- 2.
Maximum Flow Rate for RIIR Pump.
Based on actual test data, the resistance of the path directly into two cold legs was determined.
This resistance was combined with the resistance of the SI and charging pump paths to determine the equivalent resistance for the worst case configuration described in paragraph l.a.
The flows from these paths are by test procedures with flows limited to the design runout of 650 and 550 gpm, respectively.
The maximum calculated RHR pump flow rate determined from the pump curves using the equivalent resistance is 4650 gpm.
- 3.
NPSH evaluation for a flow of 4800 gpm (assumed-greater than maximum flow of RIIR pump).
a)
Pressure drop calculation on suction piping.
14 in. Dia. Piping 18 in. Dia. Piping M P79 19 30/l Pump #21 80 ft.
15 ft.
Pump #22 90 ft.
15 ft.
I
':. Calculate pressure drop for pump No. 22.
Valves and Fittings 1
6 l
14 in.
14 in.
Gate Valve @ 13 90° Ells
@ 30 18xl4 Red
@ 15 L/D 13 180 15 208 EQ Length in feet = 208 L/D x l.0937D = 227 ft.
Total Equivalent Length of Pipe and Fittings.
14 in. Pipe Section (227' + 90') -
31 7 ft.
18 in. Pipe Section -
15 ft.
Pressure drop due to friction for a flow of 4800 gpm.
For 14 in. Pipe Section@ 2.58 ft/lOOft 3.17x2.58ft= 8.18 ft 18 in. Pipe Section @0.732ft/100 ft 0.15x0.73ft= 0.11 ft Total ~ P due to friction b)
Pressure drop across containment Sump screen for a flow of 4800 gpm with 50% blockage)
Type of Screen:
Inverted box type made 8.29 ft 2.0 ft of 3/16" thick plate with 3/8" dia. perforations c)
Total losses on RHR pump suction Friction Loss Thru Pipe & Fittings 8.29 ft Entrance Loss (Assume equal to one-half 0.37 ft of velocity head)
Pressure Drop Across Sump Screen 2.00 ft Total Losses 10.66 ft M P79 19 30/2
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NPSH Available (NPSHA)
PR Elv. of water post-LOCA in containment -
81' 9"
Elv. of RHR pump (center line) 46' 10" Static head available 34' 11" (34.92')
NPSHA = ha -
hvpa + hst -
hfs where ha
= Absolute pressure in feet of liquid hvpa = The head in feet corresponding to vapor pressure of liquid hst
= Static head (in feet) hf s
= All suction losses (in feet) for Pump #22 ha
= 34 ft hvpa = 34 ft vapor pr corresponding to 212°F hst
= 34.92 ft hfs
= 10. 66 ft NPSHA = 34 -
34 + 34.92 ft -
10.66 ft
= 24.26 ft.
NPSH Required = 22 ft Extrapolated from pump graph for 4800 gpm NPSHA > NPSH Required M P79 19 30/3