ML18038A483

Responds to Request for Addl Info on Uninterruptible Power Supply Issues in 910910 Ltr

ML18038A483
Person / Time
Site:	Nine Mile Point
Issue date:	09/11/1991
From:	Firlit J NIAGARA MOHAWK POWER CORP.
To:	Varga S Office of Nuclear Reactor Regulation
References
CON-IIT07-604-91, CON-IIT07-605-91, CON-IIT7-604-91, CON-IIT7-605-91 NMP81983, NUREG-1455, NUDOCS 9109180153
Download: ML18038A483 (36)

Text

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> NIAGARA U lHOHAWK

'tc NINE MILE IVINT MUCLCAI STATION/I'.Q. 60X 32 LYCOMINQ, NBV YORK 13003/Tsl EPHONE I315I 343 2110 ph F. Firlit Ice I resident tucieer Generation NMP8 1983 September 11, 1991 Mr, Steven A, Varga Director, Division of Reactor Projects-I,II U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D. C. 20555

Dear Mr,

Varga:

Niagara Mohawk responded to your request for additional information on Uninterruptible Power Supply (UPS) issues in letter NMP2L 1315 dated September 10, 1991. A number of follow-up discussions have taken place with the NRC staff on Item 4 (Procedures and Training) of that response. The purpose of this letter is to provide additional information on Item 4 regarding means availablc to the operators to determine ifa reactor scram has occurred when control rod indication is lost due to loss of UFS1A. Furthermore, we are providing additional detail regarding our efforts to develop an alternate method to verify control rod position when indication is lost.

The steps an operator could take to verify a reactor scram without control rod position indication are detailed below, The expected response to a reactor scram included in each of these steps is discussed thoroughly during licensed operator training. The steps are listed in order of thc availability and accessibility of the information to the operator.

I. Check nuclear instrumentation response including a, AFRM's indicate less than 4% power and lowering (EOP entry condition)

b. IRM's (after driven into the core) indicate on-scale less than or equal to range 6 or 7 and lowering

c. SRM's (after driven into thc core) indicate on-scale

2. Check scram pilot valve solenoid lights are extinguished on panel 2CECWNL603

3. Check indications that steam production is at post shutdown decay heat levels (less than or equal to one turbine bypass valve or safety relief valve open, or by any available feed or steam flow indications)

I Mr. Steven A. Varga September ll, 1991 Page 4. Check main steam line radiation monitors indicate downscale (ie. normal shutdown levels) on panels 2CEC"PNL606 and 2CEC'PNL633

5. Check scram discharge volume level indication on panels 2CEC'PNL609 and 2CEC'PNL611 (Rosemount indicating trip units) for upscale or rising level 6, Check both air operated scram inlet and outlet valves at each Hydraulic Control Unit (locally) for open indication

7. Check 2RPS-PI133 locally at instrument rack 2CGS-RAK102 to verify that the scram air header has been depressurized as shown by a downscale or zero psig indication on the gauge Niagara Mohawk is actively pursuing development of an alternate method to verify control rod position by means of measurements to be taken in control room back panels for each of the one hundred eighty five control rods, It is our intent to address this issue with caution and deliberation to ensure that the activities to be included in procedures are well founded and do not create unanticipated complications for the operators. Niagara Mohawk believes this process is necessary to minimize risks associated with any activity in the control room panels.

Consequently, the procedure will be completed after plant restart.

If there are any questions on this material, please contact me at (315) 349-2447.

Sincerely, Joseph F. Firlit Yice President - Nuclear Generation

/lac

I SEP 12 '91 14:57 NNPC BADGING pc: Regional Adminis&tor, Region I Mr. W. L. Schmidt, Senior Resident Inspector Mr. R. A. Capra, Project Directorate No. I-l, NRR Mr. D. S. Brink', Project Manager, NRR Mr. C. %. Hehl, Director, Reactor Projects Mr. D. R, Haverkamp, Chief Reactor Projects, Section 1B Records Management

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WORK REQUEST DATE: DATE REQUIRED:

NAME OF REQUESTOR:

SPECIAL INSTRUCTIONS: Ig ~ + F i'le ) ~ 6 b) )

Q UK KM7'OMPLETED BY:

DATE COMPLETED:

COMMENTS:

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DCl 1C gJ i ~ '4 Ill II i phuVJIlV T NlAOARA 4 MOHAWK klNE MILE IVIkT kuCLRAN ITATIOk /P.Q. IOX 32 LYCOMIHQ, HBY YORK 13093/TELEPHONE (315) 3i3 2110

,aleph F. Firelit

., Ice President tucteor Genera tion NMP 81983 September 11, 1991 Mr. Steven A. Varga Director, Division of Reactor Projects-l,ll U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D, C. 20555

Dear Mr. Varga:

Niagara Mohawk responded to your request for additional information on Uninterruptible Power Supply (UPS) issues in letter NMP2L 1315 dated September 10, 1991. A number of follow-up discussions have taken place with the NRC staff on Item 4 (Procedures and Training) of that response. The purpose of this letter is to provide additional information on Item 4 regarding means available to the operators to determine if a reactor scram has occurred when control rod indication is lost due to loss of UPS1A. Furthermore, we are providing additional detail regarding our efforts to develop an alternate method to verify control rod position when indication is lost.

The steps an operator could take to verify a reactor scram without control rod position indication are detailed below, The expected response to a reactor scram included in each of these steps is discussed thoroughly during licensed operator training. The steps are listed in order of the availability and accessibility of the information to thc operator.

1, Check nuclear instrumentation response including

a. APRM's indicate less than 4% power and lowering (BOP entry condition)

b. IRM's (after driven into the core) indicate on-scale less than or equal to range 6 or 7 and lowering

c. SRM's (after driven into the core) indicate on-scale

2. Check scram pilot valve solenoid lights are extinguished on panel 2CECWNL603 3, Check indications that steam production is at post shutdown decay heat levels (less than or equal to one turbine bypass valve or safety relief valve open, or by any available feed or stcam flow indications)

r Mr. Steven A. Varga September 11, 1991

! Page 4. Check main steam line radiation monitors indicate downscale (ie. normal shutdown levels) on panels 2CEC~PNL606 and 2CEC~PNL633

5. Check scram discharge volume level indication on panels 2CEC'PNL609 and 2CEC'PNL611 (Rosemount indicating trip units} for upscale or rising level

6. Check both air operated scram inlet and outlet valves at each Hydraulic Control Unit (locally) for open indication

7. Check 2RPS-PI133 locally at instrument rack 2CGS-RAK102 to verify that the scram air header has bccn depressurized as shown by a downscale or zero psig indication on thc gauge Niagara Mohawk is actively pursuing development of an alternate method to verify control rod position by means of measurements to be taken in control room back panels for each of the one hundred eighty five control rods, It is our intent to address this issue with caution and deliberation to ensure that thc activities to be included in procedures are well founded and do not create unanticipated complications for the operators. Niagara Mohawk believes this process is necessary to minimize risks associated with any activity in the control room panels.

Consequently, the procedure will be completed aher plant restart, If there are any questions on this material, please contact mc at (315) 349-2447.

Sinccrciy,

?oseph F. Firlit Vice President - Nuclear Generation

/lac

'91 14:57 NNPC BADGING P 4

~

SEP 12 pc: Regional Administrator, Region I Mr. %. L. Schmidt, Senior Resident Inspector Mt. R. A, Capra, Project Directorate No, I-l, NRR Mr. D. S. Brltdanan, Project Manager, NRR Mr. C. %. Hehl, Director, Reactor Projects Mr. D. R. Haverkamp, Chief Reactor Projects, Section 1B Records Management

WORK REQUEST DATE: Q 15 'l j DATE REQUIRED'AME OF REQUESTOR:

SPECIAL INSTRUCTIONS: t3 ~ + t, 4 ) w 6, b ) >

p ug. KM7'.

COMPLETED BY:

DATE COMPLETED:

COMMENTS:

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~ NIASARA U MOHAWK NINE MILE IrOINT NUCLEAR STlTION/P.Q. 6QX 32 LYCOMINQ, NBV YORK 13II93/TELEPMONE I3IS) 343 ~ 2t to aleph F,firlit Ice 'Fr enid ent (ucleor Generation NMP819S3 September 1 l, 1991 Mr. Steven A. Varga Director, Division of Reactor Projects-l,ll U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D. C. 20555

Dear Mr,

Varga:

Niagara Mohawk responded to your request for additional information on Uninterruptible Power Supply (UPS) issues in letter NMP2L 1315 dated September 10, 1991. A number of follow-up discussions have taken place with the NRC staff on Item 4 (Procedures and Training) of that response. The purpose of this letter is to provide additional information on Item 4 regarding means available to the operators to determine ifa reactor scram has occurred when control rod indication is lost due to loss of UPS1A. Furthermore, we are providing additional detail regarding our efforts to develop an alternate method to verify control rod position when indication is lost, The steps an operator could take to verify a reactor scram without control rod position indication are detailed below. The expected response to a reactor scram included in each of these steps is discussed thoroughly during licensed operator training. The steps are listed in order of the availability and accessibility of the information to the operator,

1. Check nuclear instrumentation response including

a. APRM's indicate less than 4% power and lowering (BOP entry condition)

b. IRM's (after driven into the core) indicate on-scale less than or equal to range 6 or 7 and lowering

c. SRM's (after driven into the core) indicate on-scale

2. Check scram pilot valve solenoid lights are extinguished on panel 2CECKNL603

3. Check indications that steam production is at post shutdown decay heat levels (less than or equal to one turbine bypass valve or safety relief valve open, or by any available feed or steam flow indications)

Mr. Steven A. Varga September 11, 1991 Page 4. Check main steam line radiation monitors indicate downscale (ie. normal shutdown levels) on panels 2CEC~PNL606 and 2CEC~PNL633

5. Check scram discharge volume level indication on panels 2CEC'PNL609 and 2CEC PNL611 (Rosemount indicating trip units) for upscale or rising level

6. Check both air operated scram inlet and outlet valves at each Hydraulic Control Unit (locally) for open indication

7. Check 2RPS-PI133 locally at instrument rack 2CGS-RAK102 to verify that the scram air header has been depressurized as shown by a downscale or zero psig indication on the gauge Niagara Mohawk is actively pursuing development of an alternate method to verif'y control rod position by means of measurements to be taken in control room back panels for each of the one hundred eighty five control rods. It is our intent to address this issue with caution and deliberation to ensure that the activities to be included in procedures are weH founded and do not create unanticipated complications for the operators. Niagara Mohawk believes this process is necessary to minimize risks associated with any activity in the control room panels, Consequently, the procedure will be completed after plant restart, If there are any questions on this matenal, please contact me at (315) 349-2447.

Sincerely, Joseph F. Firlit Vice President - Nuclear Generation

/lac

SEP i2 '9l 14:57 N1PC BADGING pc: Regional Administrator, Region I Mr. W. L. Schmidt, Senior Resident Inspector Mr. R. A, Capra, Project Directorate No, I-l, NRR Mr. D. S. BrinknuLn, Project Manager, NRR Mr, C. W, Hehl, Director, Reactor Projects Mr. D. R, Haverhunp, Chief Reactor Projects, Section 18 Records Management

WORK REQUEST DATE: DATE REQUIRED:

NAME OF REQUESTOR:

SPECIAL INSTRUCTIONS: ~2 ~ ))' ) l4 1 6, )3 ) )

<T r Wm4~~

COMPLETED BY:

DATE COMPLETED:

COMMENTS:

A

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SEP 12 '91 14:56 MAC BADGIMG P.2 M U MOHAWK NINII lllLE )OINT KUCLIAll STATION/P.O. box 32 LYCOMIHQ, HEW YORK 13093/TEL%PHONE I315) 343 2t IO esephF.Firlit I resident

'ce lucIeer Genrrratian NMP8 1983 September 11, 1991 Mr. Steven A. Uarga Director, Division of Reactor Projects-l,ll U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D. C. 20555

Dear Mr,

Varga:

Niagara Mohawk responded to your request for additional information on Uninterruptible Power Supply (UPS) issues in letter NMP2L 1315 dated September 10, 1991. A number of follow-up discussions have taken place with the NRC staff on Item 4 (Prootxlures and Training) of that response. The purpose of this letter is to provide additional information on Item 4 regarding means available to the operators to determine ifa reactor scram has occurred when control rod indication is lost due to loss of UPS1A. Furthermore, we are providing additional detail regarding our efforts to develop an alternate method to verify control rod position when indication is lost.

The steps an operator could take to verify a reactor scram without control rod position indication are detailed below, The expected response to a reactor scram included in each of these steps is discussed thoroughly during licensed operator training. The steps are listed in order of the availability and accessibility of the information to the operator.

I. Check nuclear instrumentation response including

a. APRM's indicate less than 4% power and lowering (BOP entry condition)

b. IRM's (after driven into the core) indicate on-scale less than or equal to range 6 or 7 and lowering

c. SRM's (after driven into thc core) indicate on-scale 2, Check scram pilot valve solenoid lights are extinguished on panel 2CEC PNL603

3. Check indications that steam production is at post shutdown decay heat levels (less than or equal to one turbine bypass valve or safety relief valve open, or by any available feed or steam flow indications)

09. 12. 9I 03r59 PM F02

I i

f"', 3 4CP'C 2g C w 1 i )i iC4 DtlJJV s11V Mr. Steven A. Varga September 11, 1991 Page 4. Check main steam line radiation monitors indicate downscale (ie. normal shutdown levels) on panels 2CEC~PNL606 and 2CEC~PNL633 S. Check scram discharge volume level indication on panels 2CEC PNL609 and 2CEC'PNL611 {Rosemount indicating trip units) for upscale or rising level

6. Check both air operated scram inlet and outlet valves at each Hydraulic Control Unit

{locally) for open indication

7. Check 2RPS-PI133 locally at instrument rack 2CGS-RAK102 to verify that thc scram air header has been depressurizcd as shown by a downscale or zero psig indication on thc gauge Niagara Mohawk is actively pursuing development of an alternate method to verify control rod position by means of measurements to be taken in control room back panels for each of the one hundred eighty five control rods, It is our intent to address this issue with caution and deliberation to ensure that the activities to be included in procedures are well founded and do not create unanticipated complications for the operators. Niagara Mohawk believes this process is accessary to minimize risks associated with any activity in the control room panels.

Consequently, the procedure will be completed after plant restart, If there are any questions on this material, please contact me at {31S) 349-2447.

Sincerely,

'oseph F. Firlit Vice President - Nuclear Generation

/lac

09. 12. 9 I 03: 59 PM P03

'91 14: 57 NNPC BADGING P~4 SEP 12 Pi',

pc: Regional Administrator, Region I Mr. W. L, Schmidt, Senior Resident Inspector Mr. R. A, Capra, Project Directorate No, I-l, NRR Mr. D. S, Brinkman, Project Manager, NRR Mr. C. W, Hehl, Director, Reactor Projects Mr. D. R, Haverhunp, Chief Reactor Projects, Section 1B Records Management Og l2. gl Pg:gg PM PO

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NRC RESPONSE INSPECTOR: Jose Ibarra/NRC Question/Request What rad monitors were available to monitor radiation release out of the stack? Other effluents? (gaseous and liquid, concentrations, concentrate on SR and T.S. monitors)

NHPC Response The following release pathways with a description of effluent monitoring operability is discussed below. In addition, other steps were taken to help conclude that no releases of radioactive material on site or to the environment occurred.

Stack S stems 0 rable:

The Stack Gaseous Effluent Monitoring System, GEMS was operable prior to and during the event. At the time of the event the stack GEMS lost communication with the chart recorder in the main control room after the computer experienced an apparent power interruption. However, local indication was available on Turbine Building 306 and was monitored by a chem tech by approximately 0700. A computer reboot was initiated at 0805 to resolve the communication problem with the control room chart recorder.

Communication between stack GEMS and the control room recorder was restored at 0825.

S stems no rable:

None te ate Sam lin Ca 'ties:

~ GTS-105, Standby Gas Treatment System Gas Monitor, however at the time of the power loss, this monitor was not being polled by the mini computer.

~ Inplant AMS-3s with continuous readout, chart recorders and local alarm located in the Turbine Building.

~ Low volume'air samples were available and running during the event providing the capability of obtaining grab samples of Turbine Building atmosphere.

'I Vent S stems Ino rable:

The vent GENS was inoperable for scheduled calibration. The vent GEMS was inop on 8/12/91 under equipment status log entry 91-458A and returned to operable on 8/14/91.

Add'tional Information Sources:

~ Chemistry grab samples

~ Above and Below Refuel Floor gas and particulate monitors.

~ Drywell atmosphere gas and particulate continuous air monitors.

~ Inplant AMS-3s with continuous readout, chart recorders and local alarm located at various locations in the Reactor Building and Rad Waste Buildings.

~ Low volume air samples were available and running during the event providing the capability of obtaining grab samples of Reactor Building and Rad Waste Building atmosphere.

Service Water Effluent Monitoring S stem 0 rabble:

Service Water monitor SWP*146B was administratively inoperable due to repeated pump trips caused by flow switch failures. LCO grab samples were being taken. The monitor was running normally and providing information during the event.

RHR service water monitor SWP*23B was operable and available for service should operations require RHR heat exchangers to be used.

S stem Ino rable:

Service Water monitor SWP*146A was inoperable during the event.

ESL 91-456 was entered on 9/11/91 due to flow switch problems and returned to service on 8/16/91.

SWP*CAB23A was inoperable due to flow switch problems. It declared inoperable on 8/9/91 under ESL entry 91-455 and returned was to service on 8/23/91. However, this monitor was not needed since operations elected to run the B RHR loop.

Liquid Radioactive Waste Monitoring S stems 0 raMe:

The liquid rad waste monitor LWS-206 was operable but no waste releases were in progress. However, at the time of the power loss the mini computer stopped polling for information.

Cooling Tower Blowdown Monitor S stems 0 rable:

The cooling tower blowdown monitor CWS-157 was operable however, at the time of the power loss the mini computer stopped polling this non 1E monitor.

The initial response by radiation protection was in accordance with S-RPIP-10.1, "Radiation Protection Startup and Shutdown Activities".

Actions included notifying supervisions, reporting to the control room, verifying operability of control room monitors, and assigning technicians to perform plant walkdowns to report results back to the SSS an RP supervision. Radiation Monitors on Panel 880 in the control room were noted to be operating as expected with no abnormal radiation readings.

The following were utilized to gather information to assure the Emergency Director of no release of radioactive material.

~ Above and below refuel floor monitors

~ Containment atmosphere monitors

~ Drywell high range monitors Scram walkdown surveys of reactor building

~ AMS-3 portable continuous air monitors

~ Control Room air intake monitors

~ Post Accident Samples of reactor coolant

~ Down wind survey sample teams continuously obtaining air, soil and water samples.

/mak

/ I