ML19350A788
| ML19350A788 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 03/05/1981 |
| From: | Mills L TENNESSEE VALLEY AUTHORITY |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| IEB-80-06, IEB-80-6, NUDOCS 8103160844 | |
| Download: ML19350A788 (4) | |
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/YQ TENNESSEE V A,LLEY AUTHORITY CH ATTANOOG A. TENNES3EE 37 201 400 Chestnut Street Tower II
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9 Afg 2 Mr. James P. O'Reilly, Director 8 pgI A -
Office of Inspection and Enforcement
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U.S. Nuclear Regulatory Commission 9~
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101 Marietta Street q
Atlanta, Georgia 30303
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Dear Mr. O'Reilly:
SEQUOYAH NUCLEAR PLANT UNIT 1 50-327 NRC-0IE BULLETIN 80 SUPPLEMENTAL INFORMATION TVA submitted a final response to IE Bulletin 80-06 for Sequoyah unit 1 on September 15, 1980. Since that time, our ongoing review of environmental qualification of electrical equipment in accordance with NUREG-0588 has determined that under certain accident environmental conditions a number of the containment isolation valves could open upon reset of the containment isolation signal. This is caused by a lack of environmental qualificaticn for the valve limit switches. Enclosed is a list of the affected valves along with a discussion of the administrative controls established to prevent the valves from reopening after reset. The limit switches will be replaced with qualified switches during the first outage of sufficient duration after June 1, 1981.
If you have any questions, please get in touch with D. L. Lambert at FTS 857-2581.
Very truly yours, TENNESSEE VALLEY AUTHORITY t
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L.'M. Mills, Manager Nuclear Regulation and Safety Enclosure cc:
Mr. Victor Stello, Director (Enclosure)
Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission Washington, DC 20555 0
4 8103160TW Q
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,I SEQUOYAH NUCLEAR PLANT l
SUPPLEME!EAL INFORMATION ON IE BULLETIN 80-06
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.h Valves 1-FCV-1-147, -148, -149, and -150 are the main steam isolation valve bypass warmup valves utilized to warm up the secondary systems before opening the MSIV's.
The failure of the limit switches on these valves during a steamline break could cause the valves to reopen after a mainsteam isolation signal occurred.
For this to happen the valve handswitch would have to be in the A-auto position.
During normal power operation these valves are normally closed wxth their handswitches maintained in the close position.
In this situation it would be impossible for the valve to reopen if the limit switch failed. Administrative controls have been established to verify the valve handswitches in the "close" position during power operation.
Valves 1-FCV-17, -14, -25, and -32 are the outboard contain=ent isolation valves for the steam generator blowdown system. These valves are automatically closed on a containment phase A isolation or an auxiliary feedwater pump start.
If the limit switch failed, it would be possible for the valve to reopen when the containment isolation signal was reset only if the auxiliary feedwater pumps were not running. A safety injection signal is the only automatic signal resulting in a phase A isolation. This signal also results in a reactor trip, feedwater isolation, and auxiliary feedwater start.
In this situation these valves would not reopen upon resetting the containment isolation signal because of the auxiliary feedwater pump start closure signal. Administrative controls have been established to ensure the auxiliary feedwater system is in I
operation before resetting the isoletion signal following a confirmed HELB.
Valves 1-FCV-32-80, -102, and -110 are the outboard containment isolation valves for the control air system.
These valves are automatically closed on a phase B containment isolation and will remain closed regardless' of the failure of the limit switch.
The valves could reopen upon reset of the containment isolation signal if the limit switch failed in a particular manner.
Since the handswitches for these valves are located
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next to the valves inside~the annulus, it will'be< impossible'to maintain -
the valve closed from the handswitches. Administrative controls have been established to remove power from the control circuit before resetting the phase B isolation following a LOCA or HELB.
Valves 1-FCV-43-2, -11, -22, -34, and -75 are containment isolation valves for sample lines from assorted equipment inside containment.
These valves are automatically closed on a phase A containment isolation and remain closed regardless of the failure of the limit switch. The valves could reopen upon reset of the containment isolation signal if the limit switch failed in a particular manner. For this to happen the valve handswitch must be in the A-auto position. Temporary administrative controls have been-established to put the valve handswitches in the "close" position before " resetting the isolation signal.
These administrative controls will be lifted when the limit switches are replaced.
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s Valves 1-FCV-43-201, -202, -207, and -208 are containment isolation valves for containment hydrogen sampling.
The valves close on a phase A containment isolation. The failure of the limit switches could result in loss of, or incorrcet, valve position indication.
The valve will remain closed when the isolation signal is reset because the limit switch is not used as a seal-in for the circuit.
Attached is a copy of the administrative controls that have been put into effect until the limit switches are replaced.
NUREG-0578 (2.1.4) and IE Bulletin 80-06 require that the resetting of containment isolation signals shall not result in the automatic loss of containment isolation.
We believe that, with these administrative controls in place, there exists no additional risk to the health and safety of the public for the interim period until the limit switches are replaced.
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TEMPORARY ADMINISTRATIVE CONTROLS i
After a confirmed LOCA or HELB, a dedicated operator will verify the following conditions e::ist before resetting any of the indicated containment isolation signals.
Valve Cont. Iso.
Verifv The Following
- 1-FCV-1-147 NA Valve handswitch will be in the "close" position 3
- 1-FCV-1-148 NA
- 1-FCV-1-149 NA
- 1-FCV-1-150 NA 1-FCV-32-80 Phase B Control power removed from valve circuit 1-FCV-32-102 Phase B 1-FCV-32-110 Phase B Control power removed from the valve circuit or close valve 2108 1-FCV-43-2 Phase A Valve handswitch will be in the "close" position 1-FCV-43-11 Phase A 1-FCV-43-22 Phase A 1-FCV-43-34 Phase A 1-FCV-43-75 Phase A
- 1-FCV-1-7 Phase A Verify that auxiliary feedwater pumps 1A, IB, and 4
turbine driver are running and close 1-FCV-1-212 i
following a steam line isolation.
- 1-FCV-1-14 Phase A I
- 1-FCV-1-25 Phase A
"*1-FCV-1-32
?hase A 1-FCV-43-201 NA No requirements because the limit does not act as a seal-in in the circuit
.1-FCV-43-202 -
NA.
1-FCV-43-207 NA 1-FCV-43-208 NA All.of; the. position; indica, tor lights.for the listed valves may fail-or..
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-indicate incorrectly.' Should any of the above conditions not be attainable, do not reset the isolation signal.
Should the conditions inadvertently change after reset, manually reinstate the isolation signal.
- These valves should be closed and the handswitches left in the "close" position while operating in Mode 1.
1
- HELB only.
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