L-97-102, Special Rept:On 970401,Overpressure Mitigating Sys High Pressure Alert Annunciated at 400 Psig During Discussion Between Nuclear Plant Supervisor & Reactor Control Operator. Pressure Control Was Reduced & Individuals Were Counseled
| ML17354A480 | |
| Person / Time | |
|---|---|
| Site: | Turkey Point  |
| Issue date: | 04/24/1997 |
| From: | Hovey R FLORIDA POWER & LIGHT CO. |
| To: | Reyes L NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| L-97-102, NUDOCS 9705050079 | |
| Download: ML17354A480 (15) | |
Text
CATEGORY REGULATORY INFORMATION DISTRIBUTION "SYSTEM (RIDS)
ACCES'ION NBR:9705050079 DOC.DATE: 97/04/24 NOTARIZED:
NO FACIL:50-250 Turkey Point Plant, Unit 3, Florida Power and Light C AUTH.NAME AUTHOR AFFILIATION
'OVEY,R.J.
Florida Power
& Light Co.
RECIP.NAME RECIPIENT AFFILIATION REYES,L.A.
Region 2 (Post 820201)
SUBJECT:
Special rept:on 970401,"OMS PORV Actuation," was caused by
, Nuclear Plant Supervisor discussion in area of'dedica'ted RCS'ressure control Reactor Control Officer,distraction during critical evolution.NPS counseled.W/970424 ltr.
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DOCKET 05000250 INTERNAL:
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1 EXTERNAL: L ST LOBBY WARD NOAC POORE,W.
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APR 2C ]881 L-97-102 10 CFR 50.36 Luis A. Reyes USNRC Region II Atlanta Federal Center 61 Forsyth St., SW, Suite 23T85 Atlanta, GA 30323
Dear Mr. Reyes:
Re:
Turkey Point Unit 3 Docket No. 50-250 Special Report - Overpressure Miti atin S stems - PORV Actuation In accordance with Technical Specification 6.9.2, the attached Special Report is provided for your information.
Should there be any questions on this information, please contact us.
Very truly yours, R. J. Hovey Vice President Turkey Point Plant Attachment CLiiI cc:
Document Control Desk, USNRC, Washington, D.C.
T. P. Johnson, Senior Resident Inspector, USNRC, Turkey Point Plant 9'705050079 970424 PDR ADQCK 05000250 S
PDR an FPL Group company lllllllllllllllllllillllllllllllllllllll
L-97-102 Page 2 of4 SPECIAL REPORT
~Par osei This Special Report is submitted in accordance with the requirements ofTechnical Specification (T.S.) 3.4.9.3, Action e, which requires the submission ofa Special Report pursuant to T.S. 6.9.2 in the event either the Power Operated Relief Valves (PORVs) or a 2.20 square inch vent is used to mitigate a Reactor Coolant System (RCS) pressure transient.
Event and Action Taken:
On April 1, 1997, Turkey Point Unit 3 was in Mode 4 with Reactor Coolant System (RCS) pressure at approximately 300 psig, RCS average temperature at 96'F, and the Overpressure Mitigation System (OMS) operational.
Operations was performing procedure 3-OP-041.8, "Fillingand Venting the Reactor Coolant System," which requires several RCS pressure changes while the system is water solid. Evolution briefings were conducted with personnel involved, and a Reactor Control Operator (RCO) was assigned as the dedicated watchstander responsible for solid water pressure control. RCS pressure had been increased twice to about 350 psig for the one minute runs ofthe 3C and 3B Reactor Coolant Pumps (RCPs), then decreased to about 150 psig for venting.
During the pressure increase in preparation for the one minute run ofthe 3A RCP, the dedicated RCO was distracted from his primary function ofRCS pressure control by the Nuclear Plant Supervisor's (NPS's) discussion with other control room personnel concerning the ongoing evolutions. At 1:50 a.m, during this discussion, the Overpressure Mitigating System (OMS) High Pressure Alert annunciated at 400 psig. The dedicated RCO immediately stopped the running charging pump. Although no Operations personnel saw the position indication for either ofthe PORVs change or saw the PORV Open annunciator, they did hear the relays changing state, indicating an OMS actuation.
The OMS system operated as designed, with PORV (or PORVs) liAingat about 415 psig.
Reducing RCS piessure from the ope'ning setpoint to the reset pressure takes a momentary actuation ofthe PORV. One or both ofthe PORVs lifted momentarily and properly reseated as verified by an increase in the pressure and level in the Pressurizer Relief Tank at the time the RCS pressure started to decrease.
This information was obtained from the Emergency Response Data Acquisition and Display System (ERDADS).
After the event, RCS pressure was stabilized, then decreased to 300 psig and held there while the event was investigated.
L-97-102 Page 3 of4 Causes:
The primary cause ofthis event was the NPS's discussion in the area ofthe dedicated RCS pressure control RCO, distracting him during a critical evolution.
Other causal factors are as follows:
Management oversight was ineffective. The Management On Shift (MOS) is a temporary position established at the discretion ofplant management to observe on-shift activities and report concerns or unsafe acts to the NPS. The MOS designee when the PORV actuated was not in direct oversight ofa critical evolution.
2.
A slower rate ofpressure increase would have provided time for the operator to react when the OMS High Pressure Alert annunciated, without resulting in a PORV actuation, but the procedure did not specify a rate ofpressure increase.
The OMS High Pressure Alert setpoint of400 psig does not provide sufficient warning prior to the PORV actuation pressure of415 psig.
Note: Special Report L-93-28 reported the previous PORV actuation in January, 1993. Corrective Action P3 stated that, "An evaluation willbe performed to determine ifa change in the OMS alarm annunciator setpoint is necessary to allow more time for the operator to respond to an increase in RCS pressure during evolutions with the RCS in a water solid condition. The existing, alarm annunciator setpoint is 400 psig, and the PORV liftsetpoint is 415 psig."
The evaluation was completed, indicating that a lower alarm setpoint was possible, but would require additional hardware (a dual comparator).
Rather than modif~"-
'ardware, more stringent administrative controls were placed on RCS pressure limits during solid water operations.
This incident showed that, although the procedural controls were more stringent, they were not explicit, in that they did not specify a rate ofpressure increase.
Corrective Actions:
1.
The NPS was counseled concerning distracting personnel during critical evolutions.
2.
The MOS designee was counseled concerning his primary function: oversight ofcontrol room restart evolutions.
L-97-102 Page 4 of4 3.
The operator assigned as the dedicated RCS pressure control RCO was counseled on letting himself be distracted from his specific assigned responsibility.
4.
The factors leading to the PORV actuation were discussed with all personnel involved, emphasizing the importance ofmonitoring RCS pressure during solid water operations.
5.
Operations has scheduled a self-assessment, which will include this event.
6.
Procedure 3/4-OP-041.8 willbe revised to include:
a standard shift briefing emphasizing solid water operations, and that care must be taken not to distract personnel.
This briefing willalso be included in 3/4-OP-041.2, "Pressurizer Operation."
Management's expectations on the rate ofpressure increase, on use ofthe automatic mode for the pressure control valve ifavailable, on stopping at specified pressure plateaus, and a caution to monitor the rate ofchange as pressure increases.
7.
This event, and the resultant procedure changes, willbe presented to licensed operators during the pre-outage training segment ofLicensed Operator Continuing Training.
8.
The OMS High Pressure Alert setpoint willbe reduced to a lower value, as determined by Operations and Engineering.
The setpoint willbe changed prior to the Unit 4 refueling outage presently scheduled for October, 1997.
AP R 24 t997
,, L-97-102
,10 CFR 50.36 Luis A. Reyes USNRC Region II Atlanta Federal Center 61 Forsyth St., SW, Suite 23T85 Atlanta, GA 30323
'97 t1AY -2 A9:20
Dear Mr. Reyes:
Re:
Turkey Point Unit 3 Docket No. 50-250 Special Report - Overpressure Miti atin S stems - PORV Actuation In accordance with Technical Specification 6.9.2, the attached Special Report is provided for your information.
Should there be any questions on this information, please contact us.
Very truly yours, R. J. Hovey Vice President Turkey Point Plant Attachment CLM cc:
Document Control Desk, USNRC, Washington, D.C.
T. P. Johnson, Senior Resident Inspector, USNRC, Turkey Point Plant OA~qg S I
<8>
an FPL Group company
lj 1l v
L-97-102 Page 2 of4 SPECIAL REPORT
~Pur oso:
This Special Report is submitted in accordance with the requirements ofTechnical Specification (T.S.) 3.4.9.3, Action e, which requires the submission ofa Special Report pursuant to T.S. 6.9.2 in the event either the Power Operated Relief Valves (PORVs) or a 2.20 square inch vent is used to mitigate a Reactor Coolant System (RCS) pressure transient.
Event and Action Taken:
On April 1, 1997, Turkey Point Unit 3 was in Mode 4 with Reactor Coolant System (RCS) pressure at approximately 300 psig, RCS average temperature at 96'F, and the Overpressure Mitigation System (OMS) operational.
Operations was performing procedure 3-OP-041.8, "Fillingand Venting the Reactor Coolant System," which requires several RCS pressure changes while the system is water solid. Evolution briefings were conducted with personnel involved, and a Reactor Control Operator (RCO) was assigned as the dedicated watchstander responsible for solid water pressure control. RCS pressure had been increased twice to about 350 psig for the one minute runs ofthe 3C and 3B Reactor Coolant Pumps (RCPs), then decreased to about 150 psig for venting.
During the pressure increase in preparation for the one minute run ofthe 3A RCP, the dedicated RCO was distracted from his primary function ofRCS pressure control by the Nuclear Plant Supervisor's (NPS's) discussion with other control room personnel concerning the ongoing P
evolutions. At 1:50 a.m, during this discussion, the Overpressure Mitigating System (OMS) Hi h ressure Alert annunciated at 400 psig. The dedicated RCO immediately stopped the running g
charging pump. Although no Operations personnel saw the position indication for either ofthe PORVs change or saw the PORV Open annunciator, they did hear the relays changing state, indicating an OMS actuation.
The OMS system operated as designed, with PORV (or PORVs) liftingat about 415 psig.
Reducing RCS pressure from the opening setpoint to the reset pressure takes a momentary actuation ofthe PORV. One or both ofthe PORVs liAed momentarily and properly reseated as verified by an increase in the pressure and level in the Pressurizer Relief Tank at the time the RCS pressure started to decrease.
This information was obtained from the Emergency Response Data Acquisition and Display System (ERDADS).
After the event, RCS pressure was stabilized, then decreased to 300 psig and held there while the event was investigated.
L-97-102 Page 3 of4 Causes:
The primary cause ofthis event was the NPS's discussion in the area ofthe dedicated RCS pressure control RCO, distracting him during a critical evolution.
Other causal factors are as follows:
Management oversight was ineffective. The Management On Shift (MOS) is a temporary position established at the discretion ofplant management to observe on-shift activities and report concerns or unsafe acts to the NPS.
The MOS designee when the PORV actuated was not in direct oversight ofa critical evolution.
2.
A slower rate ofpressure increase would have provided time for the operator to react when the OMS High Pressure Alert annunciated, without resulting in a PORV actuation, but the procedure did not specify a rate ofpressure increase.
3.
The OMS High Pressure Alert setpoint of400 psig does not provide suAicient warning prior to the PORV actuation pressure of415 psig.
Note: Special Report L-93-28 reported the previous PORV actuation in January, 1993. Corrective Action ¹3 stated that, "An evaluation willbe performed to determine ifa change in the OMS alarm annunciator setpoint is necessary to allow more time for the operator to respond to an increase in RCS pressure during evolutions with the RCS in a water solid condition. The existing alarm annunciator setpoint is 400 psig, and the PORV liftsetpoint is 415 psig."
The evaluation was completed, indicating that a lower alarm setpoint was possible, but would require additional hardware (a dual comparator).
Rather than modify hardware, more stringent administrative controls were placed on RCS pressure limits during solid water operations.
This incident showed that, although the procedural controls were more stringent, they were not explicit, in that they did not specify a rate ofpressure increase.
Corrective Actions:
1.
The NPS was counseled concerning distracting personnel during critical evolutions.
2.
The MOS designee was counseled concerning his primary function: oversight ofcontrol room restart evolutions.
L-97-102 Page 4 of4 3.
The operator assigned as the dedicated RCS pressure control RCO was counseled on letting himself be distracted from his specific assigned responsibility.
4.
The factors leading to the PORV actuation were discussed with all personnel involved, emphasizing the importance ofmonitoring RCS pressure during solid water operations.
Operations has scheduled a self-assessment, which willinclude this event.
6.
Procedure 3/4-OP-041.8 willbe revised to include:
a standard shift briefing emphasizing solid water operations, and that care must be taken not to distract personnel.
This briefing willalso be included in 3/4-OP-041.2, "Pressurizer Operation."
Management's expectations on the rate ofpressure increase, on use ofthe automatic mode for the pressure control valve ifavailable, on stopping at specified pressure plateaus, and a caution to monitor the rate ofchange as pressure increases.
7.
This event, and the resultant procedure changes, willbe presented to licensed operators during the pre-outage training segment ofLicensed Operator Continuing Training.
8.
The OMS High Pressure Alert setpoint willbe reduced to a lower value, as determined by Operations and Engineering.
The setpoint willbe changed prior to the Unit 4 refueling outage presently scheduled for October, 1997.
~
5 ~