ML20213E685
| ML20213E685 | |
| Person / Time | |
|---|---|
| Site: | Columbia  |
| Issue date: | 11/16/1983 |
| From: | Houston R Office of Nuclear Reactor Regulation |
| To: | Novak T Office of Nuclear Reactor Regulation |
| References | |
| CON-WNP-0677, CON-WNP-677 NUDOCS 8311300240 | |
| Download: ML20213E685 (5) | |
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tie;40P.A"DilM FOR: Thomas ;1. f:ovak, Assistant Director for Licensing Division of Licensing FROM:
R.1fayne Houston, Assistant Director for Reactor Safety Division of Systems Integration
SUBJECT:
HilP-2. SSER IitPUT, FSAR SECTIO *t 7, INSTRUtlENTATI0tl Af!D C0!!TROLS Plant flane: W'!P-2 Docket f!o.:
50-397
.m Licensing Status: OL M/
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Responsible Branch:
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Project t'anager:
R. Auluck G
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Review Branch:
ICSR Review Status:
Incompl ete Enclosed is Instrumentation and Control Systens Branch (ICSB) input for Section 7 (Instrumentation and Controls) of the Nf;P-2 Supplemental Safaty Evaluation Report (SSER). This input addresses confimatory issues 13
( Automatic Restart of the Reactor Core Isolation Cooling Systen - RCIC),
la (Fodifications to Prevent Spurious RCIC Isolation), and 17 (Autonatic Transfer of RCIC Suction from the CST to the Suppression Pool).
Hased upon our review of infomation provided by the applicant (Vashington Pub-lic Power Supply System) in letter G02-03-755 dated August 23, 1983, we have concluded that these issues are resolved.
['Uf?2!8': Tad By M. k';.'hyctcn R. Wayne Houston, Assistant Director for Reactor Safety Division of Systens Integration DISTRIBUTION:
Enclosure:
Docket File As stated ICSB R/F en all W)(2) cc:
R. i'attson osa A. Schwencer
- "U" R. Auluck C. Rossi g-xp~..
T. Collins
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0311300240 831116 G-ADoCK 05000397
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DEdICuAiD ORIGIh.6-Cert 1tged 3y hl,
/f n, 7.4.2.1 Reactor Core Isolation Cooling (RCIC) System' The RCIC system is designed to maintain or supplement reactor vessel water inventory when the reactor vessel has been isolated and acts as a backup to the high pressure core spray system (HPCS) to mitigate the con-sequences of a rod drop accident.
The RCIC system auto-matically initiates on reactor vessel low water level (Level 2).
A one-out-of-two taken twice logic is used for RCIC initiation.
The WNP-2 RCIC system has been modified in accordance with TMI Action Plan Item II.K.
3.13 (Separation of High-Pressure Coolant Injection and Reactor Core Isolation Cooling System Initiation Levels -
Analysis and Implementation) to provide automatic re-start capability.
RCIC flow is automatically stopped on reactor vessel high water level (Level 8) by closing the steam supply valve (E51-F045) to the RCIC turbine.
A two-out-of-two logic is used for this function to pre-vent a single failure within the logic circuitry from isolating the steam supply line, thus preventing RCIC initiation.
When the vessel water level falls below level 8, steam supply valve E51-F045 remains closed.
The RCIC level 8 signal, however, clears at this point to allow E51-F045 to re-open if the vessel water level should reach the level 2 RCIC initiation setpoint.
The level 8 signal clears using a one-out-of-two logic so that a single failure within the logic circuitry will not prevent RCIC restart.
When level 2 is reached, valve E51-F045 re-opens allowing RCIC flow to the
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- c reactor vessel.
Following initiation, the RCIC system is designed to automatically maintain vessel level be.
tween level 2 and level 8 until control is taken over manually by the operator (s).
The staff concludes, based on its review of the RCIC schematic / elementary diagrams that this design complies with the requirement for auto-matic restart capability for the RCIC system, and there-fore, is acceptable.
This resolves confirmatory issue 13.
The WNP-2 RCIC system has also been modified to prevent spurious isolation in accordance with TMI Action Plan Item II.K.3.15 (Modify Break-Detection Logic to Prevent Spurious Isolation of High-Pressure Coolant Injection and Reactor Core Isolation Cooling).
The RCIC system uses differential pressure sensors on elbow taps in the steam supply line to the RCIC turbine to detect and isolate pipe breaks in the system.
Sensor E31-N013A provides a signal to close RCIC steam supply line out-board isolation valve E51-F008 on high differential pressure.
Similarly, inboard isolation valve E51-F063 closes on a high differential pressure signal from sen-sor E31-N0138.
Time delay relays (3 seconds) have been
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added to the RCIC isolation actuation logic to ensure that isolation is based on continuous high steam flow, and to prevent pressure spikes resulting from RCIC ini-tiation from causing spurious isolation.
The staff
-3 concludes, btsed on its review of the RCIC schematic /
elementary diagrams, that this design complies with the requirement to prevent spurious RCIC isolation, and therefore, is acceptable.
This resolves confirmatory issue 14.
The primary source of water for the RCIC system is from the non-seismically qualified condensate storage tanks (CSTs).
The RCIC system has been modified to provide automatic transfer of RCIC pump suction from the CSTs to the suppression pool on low water level in the CSTs.
The sensors used to initiate transfer (E51-N015A and E51-N0158) are seismically qualified and are located on the seismically qualified suction line from the CSTs.
When either sensor detects low water level in the CSTs, a signal is generated to open RCIC pump suc-tion valve E51-F031 from the suppression pool.
A limit switch mounted locally at valve E51-F031 provides a signal to close the RCIC suction valve E51-F010 from the CSTs when the suction valve from the suppression pool reaches the fully open position.
A manual override is provided to allow the operator (s) to close valve E51-F031 following an automatic transfer if required.
A white status light is provided in the control room to indicate when the override is in effect.
The staff concludes, based on its review of the RCIC schematic /
elementary diagrams, that this design complies with the
. requirement for automatic transfer of RCIC pump suction to a seismically qualified water source, and therefore, is acceptable.
This resolves confirmatory issue 17.
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