ML20045E681
| ML20045E681 | |
| Person / Time | |
|---|---|
| Site: | Oyster Creek |
| Issue date: | 06/28/1993 |
| From: | J. J. Barton GENERAL PUBLIC UTILITIES CORP. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20045E682 | List: |
| References | |
| C321-93-2009, GL-89-10, NUDOCS 9307020313 | |
| Download: ML20045E681 (8) | |
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GPU Nuclear Corporation JF ggI f
Post Office Box 388 -
Route 9 South Forked River, New Jersey 08731-0388 609 971-4000 Writer's Direct Dial Number:
C321-93-2009 June 28, 1993 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555 Gentlemen:
Subject:
Oyster Creek Nuclear Generating Station Docket No. 50-219 Generic Letter 89-10, " Motor Operated Valves" Response to Request for Additional Information By letter dated November 25,1992, the USNRC requested that additionalinformation be provided by GPU Nuclear to address NRC concerns with operator actions taken during a LOCA on the Isolation Condenser System. The letter originally requested that the information be provided within 30 days. Subsequent to that letter, GPUN requested and received an extension of that time period.
Enclosure I to this letter provides an item by item response to NRC request for additional information. If any further information should be required, please contact Mr. David-Distel at 201.316.7955.
Sincer-ly W
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'ohn J.
on Vice Pr ident and Director Oyster Creek Nuclear Generating Station JJB/DJD/JJR.
g Enclosure ec: Administrator, Region I Oyster Creek NRC Project Manager Senior Resident NRC Inspector 9307020313 930628 PDR ADOCK 05000219
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GPU Nuclear Corporavon is a subsidia y of General Public Utihties Corporation
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NUCLEAR GENERATING STATION-r e
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REQUESTED INFORMATION.
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C321-93-2009 Enclosure I Page1 NRC REQUEST 1:
Provide a copy of the current revision to the following alarm / annunciator response procedures (RAPS):
2000-RAP-3024.01, the RAP for "ICS A & B High Flow-Possible Rupture a.
Alarm" b.
The RAP for " Condenser A or B Vent Hi Alarm" c.
All RAPS associated with alarms on isolation condenser temperature or level.
GPUN RESPONSE 1:
Attachment I to this enclosure dockets the applicable sections of the current revision to OCNGS station Procedure 2000-RAP-3024.01, "NSSS Annunciator Response Procedures." The procedure also contains the anm.nciator panellayouts.
Please note that Attachment I includes only the alarm response procedure (RAP) -
sections related the Isolation Condenser System (ICS).
NRC REQUEST 2:
State the location (building, room, and panel) and exact labeling associated with each of the following alarms or indications:
a.
"ICS A&B High Flow-Possible Rupture Alarm" b.
" Condenser A or B Vent Hi Alarm" c.
Isolation condenser temperature alarms or indications d.
Isolation condenser level alarms or indications e.
Redundant indicators of high radiation level
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l C321-93-2009 Enclosure I Page 2 GPUN RESPONSE 2:
All of the specified alarms and indications are displayed in the Control Room, located in the Main Office Building, third floor.
The specific location and labeling of each requested alarm are as follows:
2a.
" Condenser A Flow HI Possible Rupture"
" Condenser B Flow HI Possible Rupture" These specified alarms are located on Annunciator Panel "C" and are shown under Group Headings C-3-a and C-3-b. Annunciator Panel C is on Control-Room Panel IF/2F.
Attachment I to this enclosure also includes the Annunciator Panel C layout.
2b.
"A Vent HI" "B Vent HI" These specified alarms are located on Annunciator Panel 10F and are shown under Group Headings 10F-1-e and 10F-2-e. Attachment I to this enclosure also includes the Annunciator Panel 10F layout.
2c.
"Shell Temp HI" "Cond Area Temp HI" The specified alarms are located on Annunciator Panel C and are shown under Group Headings C-7-b and C-8-b. Attachment I to this enclosure also includes the Annumciator Panel C layout. Area temperature indication is available on Control Room Panel 10R.
2d.
"Shell A LVL HI/LO" "Shell B LVL HI/LO" The Specified alarms are located on Annunciator Panel C and are shown under group headings C-6-a and C-6-b. Attachment I to this enclosure also 1
includes the Annunciator Panel C layout.
2e.
Redundant indicators of high radiation level are available on Control Room Panel 2R.
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C321-93-2009 1
Enclosure I Page 3
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NRC IEQUEST 3:
Describe all ICS timers incorporated in alarms, indications, or automatic actions i
in addition to the "ICS A & B High Flow-Possible Rupture" alarm.
i GPUN IESPONSE 3:
ICS is initiated by reactor vessel high pressure or lo-lo water level signals which cause the normally closed condensate return line isolation valves to open. A 1.5 second time delay was included in the automatic initiation of the ICS in order to prevent ICS initiation under certain transient conditions. Once ICS automatic initiation is activated, it takes approximately 20 seconds for the condensate return valve to fully open.
The high flow trip setpoints for the Isolation Condenser provide automatic isolation of both the steam and condensate lines. _ A pipe rupture would be indicated by a signal of three hundred percent of normal flow lasting for at least 35 seconds. As described in OCNGS FSAR Section 6.3.2.5, line breaks equivalent to 300% of -
normal flow can be tolerated without an isolation. For complete line breaks, the isolation trip occurs and the valves close in a maximum Technical Specification allowed time of 60 seconds.
After the 35 second time delay has timed out, a coincident signal is sent to annunciate alarm windows C-3-a and C-3-b, "ICS A&B High Flow-Possible Rupture Alarm", and to close the ICS isolation valves. Please note that the alarm windows are not annunciated in the control room until the 35 second high flow sensor time delay has timed out. Therefore, for the initial 35 second time period, the operator must visually verify the changing plant conditions on four different Control Room Panels as indicated in Attachment Il to this enclosure.
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NRC REQUEST 4:
State the specific alarms and/or indications that are used to verify an ICS pipe rupture as presented in training and/or written guidance.
L GPUN RESPONSE 4: (Refer to Attachment Il for Panel locations)
Group IIcadine C-8-b:
Condenser Area Temperature HI Confirmatory actions: Directs the operator to check for system isolation at Panel' IF/2F, check local alarm indicator on Panel 10R for affected area, and check radiation levels ofisolation condenser area on Panel 1R/2R.
Corrective actions: Directs the operator to evacuate the Reactor Building; and only after an ICS leak or pipe break is confirmed, isolate the affected system by placing the control switches for the Isolation and Vent Valves to the close position.
Group IIeadings 10F-1-e and 10F-2-e: Vent HI (Radiation) l Confirmatory actions: Directs the operator to verify the high radiation level on j
redundant indicators on Panel 2R. A cautionary note to the operator in the RAP j
identifies that this alarm is not positive indication of a leak because of the j
closeness of the radiation monitor to the isolation condensers.
Corrective actions:
Directs the operator to check the isolation condenser
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temperature and level for indications of tube leakage and to sample the shell side for activity. The operator is then directed to manually isolate the affected isolation condenser if necessary.
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l C321-93-2009 Enclosure I i
Page 5 AFTER 35 SECONDS IIAVE TIMED OUT:
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Group IIeadings C-3-a and C-3-bl Condenser A or B HI Flow Possible Rupture Confirmatory actions:
Directs the operator to confirm Annunciator C-8-b, Condenser Area Temperature HI alarm, area temperature indication increase at Panel 10R, and closure of the respective isolation valves. Additionally forICS in standby mode, condenser level and temperature indication changes are confirmed on Panel 2F.
r Corrective actions: Directs the operator to place the control switches for the A or B Isolation Condenser and Vent Valves in the close position only after a pipe break has been verified and Reactor Building evacuation has been ordered.
r SIGNIFICANTLY LATER (Not Part ofICS Leak Actionsh Group IIeadings C-6-a and C-6-b: Condenser A or B HI or Low Water Level Confirmatory actions: Directs the operator to check level indicators at Panel 1F/2F.
Corrective actions: Directs the operator to determine the cause of High/ Low level and restore level in accordance with system procedures. No guidance is given with respect to ICS isolation for this annunciator alarms.
Gmtlp Ileadine C-7-b: Condenser Shell Temperature HI Confirmatory actions: Directs the operator to check the temperature recorder IG02 on Panel IF/2F for location of high temperature.
Corrective actions: Directs the operator to verify valve positions to check for leakage past the valves.
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4 C321-93-2009 Enclosure I Page 6 NRC REQUEST 5:
l Since no guidance or direction is given regarding overriding the 35 second delay to manually isolate the ICS on an immediate basis, describe in detail how you assure that an operator will not close the ICS condensate line isolation valves as soon as the pipe break is verified.
GPUN RESPONSE 5:
Alarm response procedures direct the operator to close the isolation valves when an ICS pipe break is verified. However, it has been and continues to be the GPU i
position that the operator p_a_nnal verify the source of the leak and therby determine-that valve closure is necessary within 35 seconds.
The design basis for the ICS provides the 35 second time delay for the-specific purpose of avoiding a spurious isolation due to recirculation pump coastdown following an ATWS trip signal. As identified in response to Question Nos. 3 and 4 above, the possible rupture alarm is only annunciated in the control room concurrently with an automatic isolation of the affected isolation condenser, only l
after the 35 second high flow time delay has timed out. As discussed in the response to request 4, it would take significantly longer than the 35 second time period allowed for an operator to follow the requirements of the multiple procedures and visually verify that a LOCA existed and was from an isolation condenser.
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