ML19259C126
| ML19259C126 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun  |
| Issue date: | 06/06/1979 |
| From: | Short T OMAHA PUBLIC POWER DISTRICT |
| To: | Reid R Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 7906120387 | |
| Download: ML19259C126 (9) | |
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Omaha Public Power District 1623 HARNEY a OMAMA. NEBRASMA 68102 e TELEPHONE 53 6 4000 ARE A CODE 402 June 6, 1979 Director of Nuclear Reactor Regulation ATHI:
Mr. Robert W. Reid, Chief Operating Reactors Branch No. 4 U. S. Nuclear Regulatory Commission Washington, D. C.
20555
Reference:
Docket No. 50-285 Gentlemen:
In response to a telephone conversation held with Mr. E. Butcher of the Com.ission's staff on May 17, 1979, please find attached addi-tional information in regard to unqualified lim.t.
avitches at the Fort i
Calhoun Station. This information provides support to the Omaha Public Power District's response to IE Bulletin 79-01, dated May 15, 1979 Sincerely,
,I
- ; _. i
,- T. E. Short Assistant General Manager TES/KJM/BJH:Jem Attach.
cc: LeBoeuf, Lamb, Leiby & MacRae 1333 New Hampshire Avenue 22h4 2h9 Suite 1100 Washington, D. C.
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_UNOUALIFIED LDviIT SWITCHES
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Several types of limit switches were identified in the Fort Calhoun s
Nuclear Station as being unqualified for service in a LOCA environment.
The types identified, their location, tag number, and valve positioning during the postulated accident is depicted below:
Limit Safety
'A ccident Valve No.
Switch Print No.
Energize To Fall-Pos ition Position
- NAMCO (GHDR Series)
Clos e Open Closed (CIAS)
HCV-881 D 1200G-2 11405 -M-1 NAMCO HCV-882 D1200G-2 11405 -M -1 Close Open Closed (CIAS)
NAMCO HCV-883A D1200G -2 11405-M-1 Clos e Open Closed (CIAS)
NAMCO HCV-884A D1200G-2 11405-M-1 Clos e Open Closed (CIAS)
NAMCO HCV-438A D1200G-2 11405-M-40 Close Open Closed (CIAS)
NAMCO HCV-438C D 1200G-2 11405 -M-40 Close Open Closed (CIAS)
NAMCO HCV-467A D 1200G-2 11405 - M-40 Open Closed Closed (CIAS)
NAMCO HCV-467C D1200G-2 11405-M-40 Open Closed Closed (CIAS)
NAMCO HCV-425A D 1200G -2 11405 -M-40 Open Clos ed Closed (CIAS)
NAMCO HCV-425C D1200G-2 11405-M-40 Open Closed Closed (CIAS)
NAMCO TCV-202 D1200G-2 CE-23866-210- Open Closed Closed (CIAS) 120 NAMCO No Automatically HCV-238 D1200G-2 CE-23866-210- Close Open Initiated Accident 120 Position
- Actuating Signal 2284 290 1
. _-a Unqualified Limit Switches (Continued)
Limit Safety Accident l
Valve No.
- Switch
- - - Print No.-
Energize To Fail-Position Position
- j No Automatically
^
NAMCO HCV-239 D1200G-2 CE-23866-210 -120 Close Open Initiated Accident Position NAMCO HCV-240 D 1200G-2 CE-23866-210-120, _ Open Closed NAMCO HCV-241 D 1200G -2 CE-23866-210 -120 Open Closed Closed (CIAS)
NAMCO HCV-2504A DE*00X 11405 - M-12 Open Clos ed Closed (CIAS)
NAMCO HCV-2506A D2400X 11405-M-12 Open Closed Closed (CIAS)
NAMCO HCV-2507A D2400X 11405-M-12 Open Closed Closed (CIAS)
NAMCO PCV-2909 D2400X CE-23866 -210 -13 0 Open Closed Closed (SIAS)
NAMCO PCV-2929 D2400X CE-23866-210-130 Open Closed Closed (SIAS)
NAMCO PCV-2949 D2400X CE-23866 -210 -13 0 Open Closed Closed (SIAS)
NAMCO PCV-2969 D2400X CE-23866 -210 -13 0 Open Clos ed Closed (SIAS)
Fisher (CIAS or HCV-1387A Type 304 11405-M-253 Open Closed Closed High Radiatior Fisher HCV-1388A Type 304 11405-M-253 Open Closed C los ed.
Fishc,
HCV-2603B Type 304 11405-M-42 Open Closed Closed (CIAS) b 2
- Actuating Signal 2
Unqualified Limit Switches (Continued)
Limit A ccident Valve No.
Switch Print No.
Energize To Fall-Position Pos ition* -
s Fisher HCV-2604A Type 304 11405 - M-42 Open Closed Closed (CIAS)
Fisher C
HCV-1107A Type 304 11405 M-253 Clos e Open
~ Open (CIAS)
Fisher HCV-1108A Type 304 11405-M-253 Clos e Open Open (CIAS)
Fisher (VIAS or PCV-742E Type 304 11405-M-1 Open Clos ed Closed CIAS)
Fishe r PCV-742G Type 304 11405-M-1 Open Closed Closed Fishe r HCV-746A Type 304 11405-M-1 Open Clos ed Closed Fisher No Automatically HCV-545 Type 304 C E-23866-210 -130 Open Closed Initiated Accident Position Fisher HCV-2916 Type 304 CE-23866-210-130 Open Closed Closed (CIAS)
Fisher HCV-2936 Type 304 C E-23 866 -210 -130 Open Clos ed Closed (CIAS)
Fisher HCV-29S6 Type 304 CE-238 66-210 - 130 Open Closed Closed (SIAS)
Fisher HCV-2976 Type 304 CE-238 66 -210-13 0 Open Clos ed Closed (SIAS) 2284 292
- Actuating Signal 3
Unqualified Limit Switches (Continued) 1.
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T As previously discussed in the 14-day submittal with LER 79-007, four possible modes of limit switch failure were postulated. These modes of limit switch failure are listed below, along with the postulated consequences corresponding to each of the failure modes:
Mode 1) Limit Switch Short Circuits - this would result in.
O possible indication of both "open" and " closed" position of the valve, i. e., both lights could pos sibly be lit. If such is the case, the Fort Calhoun operators have been instructed to rely upon related process instrurnentation for indication of true valve position.
Mode 2) Limit Switch Open Circuits - this would result in a complete loss of position indication. Again, operators have been instructed to be aware of this condition and if nec-essary rely upon the appropriate process instrumentation for valve indication.
Mode 3) Grounding of the power supply through limit switch failure - again, as stated in the previous submittal, the Fort Calhoun instrument buses are designed to operate with a ground. The circuit design is such that only one line-to-ground fault would occur, i. e., the negative bus would be grounded and the other line is held above ground by the resistance of the light indication circuitry, (refer to figure 1 attached). It was previously stated that in the event both lines, positive and negative were grounded, the control fuses located in the individual containment isolation valve circuit would " blow" and the valve would assume its fail-safe posi-tion. This statement should be clarified by saying that it is unlikely that the grounding of the positive and negative leads of the limit switch would cause the fuse to " blow" since the resistance of the light indicator circuitry would tend to hold the voltage of the circuit above ground, (refer to figure 1).
It is our belief that since the light bulb resistance makes up the major portion of the total circuit resistance, it would be extremely unlikely that the grounding of the limit switches would cause the control fuses to " blow".
However, if the fuses were to blow, the valve would go to its
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fall-safe position. In the extremely unlikely event that the fuses to a particular valve were to blow, the limit switch leads may be disconnected, thus eliminating them from the circuit.
Upon doing so, the fuses may be replaced and the o grabili of
/21429 Dysw yE N~hki/
4
Unqualified Limit Switches (Continued)
E the valve will be restored. It is pointed out as a reminder that in cer-
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f tain circurnstances, if a control circuits' fuses were blown causing the valve to go to its fail-safe position, the desired or accident position may not be attainable. In such circumstances redundant (outside con-tainment) valves provide the necessary isolation. For example, HCV-881--this valve's accident position is closed but its fail-safe position 2
is open. If the control circuit fuses to this valve were blown immedi-ately following a LOCA, the valve would go to its fail-safe (open) posi-tion until operability to the valve could be restored. During the interim however, isolation may still be provided by valves located outside the containment.
Mode 4) Tracking to the solenoid valve - as discussed per previous sub-mittal, it was concluded that the occurrence of " tracking" will not cause any malfunction or loss of valve operability and will not inhibit any valve from carrying out its intended design function. In addition, tracking would not cause the malfunction of any other safety related equipment.
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Unqualified Limit Switches (Continued)
Listed below are the functions of the valves in question:
VALVE NO.
HCV-881 Isolation valves leading to hydrogen purging equipment.
HCV-882 HCV-883A Isolation valves leading to the hydrogen analyzer. ~
HCV-884A HCV-438A Isolation valves for component cooling water piping lead-HCV-438C ing to the RC pump lube oil coolers.
HCV-467A Isolation valves for component cooling water piping lead-HCV-467C ing to the Nuclear detector well cooling units.
HCV-425A Isolation valves for component cooling water piping lead-HCV-425C ing to the safety injection leakage coolers.
TCV-202 Isolation and " backup" isolation valves off CVCS piping i
HCV-238 leading to the respective RC loops.
HCV-239 HCV-240 HCV-241
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HCV-2504A Isolation valves for RC sampling lines.
HCV-2506A Isolation valves for S/G sampling lines.
HCV -2507A PCV-2909 Valves which isolate the safety injection piping from PCV-2929 the safety injection leakage coolers.
PCV-2949 PCV-2969 HCV-1387A S/G blowdown isolation valves.
HCV-1388A HCV-2603B Nitrogen isolation valves supplying pressure to the SI HCV-2604A tanks.
HCV-1107A Isolation valves leading to the auxiliary FW pipMg.
HCV-1108A PCV-742E/GIsolation valves leading to RM 050/051.
2284 295 6
Unqualified Limit Switches (Continued)
VALVE NO.
HCV-746A Isolation valves for containment relief.
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HCV 8/5 Isolation valve for safety injection water to and from i
leakage coolers.
HCV-2916 Isolation / drain valves off the SI tanks.
O HCV-2936 HCV-2956 HCV-2976 2284 296 7
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