ML20012E800
| ML20012E800 | |
| Person / Time | |
|---|---|
| Site: | Trojan File:Portland General Electric icon.png |
| Issue date: | 03/30/1990 |
| From: | Walt T PORTLAND GENERAL ELECTRIC CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| GL-88-17, NUDOCS 9004060328 | |
| Download: ML20012E800 (24) | |
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March 30, 1990 i
l Trojan Nuclear Plant l
Docket 50-344 License WPF-1 U.S. Nuclear Regulatory Commission ATTN Document Control Desk Washington DC 20555
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Dear Sir:
Status Update for Response to Generic Letter 88-17, Loss of Decay Heat Removal l
1 Information is provided in the attachments to this letter to update the status of actions taken by Portland General Electric (PCE) to implement the recommended expeditious actions and recommended programed enhancements identified in Generic Letter 88-17.
PCE's initial responses to the recommended expeditious actions and recommended programmed enhancements were provided pursuant to your request under Title 10, code of Federal Reguistions, Part 50, Section 54(f) [10 CFR 50.54(f)), in letters dated January 16, 1989 and February 6,1989, respectively. The status update indicates the efforts completed, the tasks redefined, and new completion dates for remaining work.
Sincerely.
l T. D. Walt p
Acting Vice President, Nuclear Attachments
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Mr. John B. Martin M ou.
Regional Administrator, Region V
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U.S. Nuclear Regulatory Commission Mr. David Stewart-Smith
.g mu State of Oregon 1
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'jG at Mr. R. C. Barr NRC Resident Inspector
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Trojan Nuclear Plant 9Subscribedands I
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Votary Pu ic/of Oregon
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121 S.W Salmon Street. Pod;and. Oregon 97204 e
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Trojtn Nuc10;r Plcnt Document Contral Deck Docket 50-344 Attachment A License NPF-1 March 30, 1990 Page 1 of 8 PORTLAND CENERAL ELECTRIC COMPANY (PGE)
RESPONSE TO EXPEDITIOUS ACTIONS IDENTIFIED IN CENERIC LETTER 88-17 t
WRC RECOMMENDATION NO. 1 l
Discuss the Diablo Canyon event, related events, lessons learned, and implications with appropriate Plant personnel.
Provide training shortly l
before entering reduced inventory condition.*
Response
PCE will comply with the above recommendations by including addi-tional training in the 1989 design change /preoutage training sessions provided for all licensed and non-licensed operators.
Status Update This task was completed prior to conducting reduced inventory operations during the 1989 Refueling Outage.
NRC RECOMMENDATION NO. 2 Implement procedures and administrative controls that reasonably assure that Containment closure ** will be achieved prior to the time at which a core uncovery could result from a loss of DHR coupled with an inability to initiate alternate cooling or addition of water to the Reactor Coolant System (RCS) inventory. Containment closure procedures should include consideration of potential steam and radioactive material release from the RCS should closure activities extend into the time boiling takes place within the RCS. These procedures and administrative controls should be active and in use:
1.
Prior to entering a reduced RCS inventory condition for Nuclear Steam Supply Systems (NSSS) supplied by Combustion Engineering or Westinghouse, and 2.
Prior to entering an RCS condition Wherein the water level in lower than 4 inches below the top of the flow area of the hot lega at the junction of the hot legs to the reactor vessel (RV) for NSSSs sup-plied by Babcock & Wilcox, and should apply Whenever operating in
- A reduced inventory condition exists whenever reactor vessel (RV) water level is lower than 3 feet below the RV flange.
- Containment closure is defined as a Containment condition whero at least one integral barrier to the release of radioactive material is provided.
Further discussion and qualifications which the integral barrier must meet are provided in Enclosure 2 and in the definitions provided in Enclosure 3.
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i Trojan Nuclear plant Document Control Desk j
Docket 50-344 Attachment A License NpF-1 March 30, 1990 l
page 2 of 8 those conditione.
If such procedures and administrative controls are not operational, then either do not enter the applicable condition or
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maintain a closed Containment.
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Response
Guidance for Containment isolation to establish integrity in the event of a prolonged loss of DHR while drained down to loop centerline (Elevation 60 feet 2 inches) in Mode 5 is provided by Administrative Order (AO)-3-11. " Containment Access and Evacuation". The rrc^edure will be revised prior to the next drain down to specify er 9'cability any time the vessel level is lowered bolow 3 feet below the RV flange elevation (64 feet 1-3/4 inch) and irradiated fuel is in the rector.
The procedure provides for prompt restoration of modified containment integrity following loss of residual heat removal (RHR) forced cool-ing. Modified Containment integrity is currently defined as meeting the integrity requirements specified in Trojan Technical Specifi-cation 3.9.4.
However, this is a refueling section Technical Specification with a basis related to a fuel-handling accident, not a Containment pressurizatloa event.
PGE recognizes NRC concerns related to events that result in Contain-ment pressurization. Therefore Administrative Order (AO)-3-11 will be revised to require that all open Containment penetrations not capable of being isolated by a closed valve be provided with a blank flange or cover that can be bolted or clamped over the opening, if required.
The status of each penetration that could provide direct access between the Containment and outside atmosphere, if open, is main-tained on a Containment penetration integrity restoration plan work sheet required by A0-3-11.
Each plan provides for closing the penetration within 2-1/2 hours of losing DHR capability.
j The 2-1/2 hour time is the time to core uncovery calculated using l
control room operating curves based on the maximum core decay heat l
condition, assuming a minimum reactor shutdown time interval of l
10 days.
This time is conservative, as it is based on 255 days of I
full-power operation and a vessel level of 60 feet 2 inches.
If the time since reactor shutdown is less than 10 days, as assumed in Operating Instruction (0I)-3-2, Draining the Reactor Coolant System, and 2-1/2 hours is considered insufficient time to restore Contain-(
ment integrity, then the curves are consulted to establish actual time l
to core uncovery.
If necessary, the Supervising Engineer, Reactor Engineering, it consulted to provide an estimation of time until core uncovery based on actual reactor shutdown time and power history.
procedure changes will be made to implement the more stringent time limitations (discussed in Section 2.2.2 of Enclosure 2 to Generic Letter 88-17) related to openings totaling greater than 1
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e Trojan Nuclear plant Document Control Desk Docket 50-344 Attachment A License NpF-1 March 30, 1990 page 3 of 8 one square inch in the cold legs, reactor coolant pumps (RCps) and crossover piping of the RCS.
In the event closure ectivities extend into the time boiling takes place within the RCS, control of effluent from the Containment would be through condensation of steam at the Containment air coolers, with subsequent Containment sump transfer to the Dirty Waste Drain Systam.
t Caseous releases would be monitored via Reactor and Auxiliary Building process radiation monitors.
Status Update This task was completed prior to conducting reduced inventory operations during the 1989 Refueling Outage.
NRC RECOMMENDATION No. 3 provide at least two independent, continuous temperature indications that are representative of the core exit conditions whenever the RCS is in a mid-loop condition
- and the reactor vessel head is located on top of the RV.
Temperature indications should be periodically checked and recorded by an operator or automatically and continuously monitored and alarmed.
Temperature monitoring should be performed either:
1.
By an operator in the control room, or 2.
From a location outside the Containment Building with provision for providing immediate temperature values to an operator in the control room if significant changes occur. Observations should be recorded at an interval no greater than 15 minutes during normal conditions.**
Response
The temperature of the RCS when drained and vented is monitored with the temperature indicators in the RHR System and the core exit thermocouple system. The RHR System temperature indication is the principle means for monitoring temperature under drained and vented system conditions. However, should the RHR System fall to function, the in-core exit thermocouples remain functional and are a valid indication of the RV/ core temperature. A minimum of two in-core exit thermocouples are kept in service and can be monitored from the control room whenever the RCS is drained 3 feet below the RV flange.
- A mid-loop condition exists Whenever RCS water level is below the top of the flow area of the hot legs at the junction with the RV.
- Cuidance should be developed and provided to operators that covers evacuation of the monitoring post. The guidance should properly balance reactor and personnel safety
Trojan Nuclear plant Document Control Desk
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Docket 50-344 Attachment A License NpF-1 March 30, 1990 page 4 of 8
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The RHR system temperature is continuously recorded in the control room and is normally displayed on the plant computer for continuous operational information.
In the event RHR flow is lost, the operator will monitor core exit conditions by use of the in-core thermo-l couples. Thermocouple temperatures can be read on a local indicator or the plant computer, both of which are located in the control room, plant procedures will be revised to require the control room oper-ator to set the RHR heat exchanger inlet tamparature and in-core exit i
thermocouple computer signals to provide alarms on the in-plant computer when RCS temperatures exceed specified values.
Status Update This task was completed prior to conducting reduced inventory operations during the 1989 Refueling Dutage.
Temporary disconnection of the in-core exit thermocouples is minimized in duration and limited to conditions in which preparatioh for reactor vessel head movement during reduced inventory conditions requires temporary disconnection.
.NRC RECOMMENDATION NO 4 provide at least two independent, continuous RCS water level indications whenever the RCS is in a reduced-inventary condition. Water-level indi-cations should be periodically checked and recorded by an operator or automatically and continuously monitored and alarmed. Water-level moni-toring should be capable of being performed either:
1.
By an operator in the control room.
2.
From a location other than the control room with provision for providing immediate water level values to an oporator in the control room if significant changes occur. Observations should be recorded at an interval no greater than 15 minutes during normal conditions.**
Response
The shutdown reactor vessel level indication system provides the operators in the control room with indication of vessel level during plant operating Modes 5 and 6.
The system consists of two separate tubing / standpipe designs Which include RCS taps at RCS Flow Trans-mitters FT-425 and FT-435, and two 25-foot-long tempered glass standpipes, with vent paths to the pressurizer spray vont line and I
pressurizer sampling system vont line.
The system consists of the l
following:
- Cuidance should be developed and provided to operators that covers evacuation of the monitoring post. The guidance should properly balance reactor and personnel safety.
l Trojan Nuclear plant Document Control Desk Docket 50-344 Attachment A
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License NpF-1 March 30, 1990 page 5 of 8 1.
Remote (inside Containment) visual indication of RV level from the SS-foot elevation to 80-foot elevation.
2.
A camera mounted inside containment is focused on the standpipes (LO-040B and -1040C) at RCS loop centerline (60 feet j
1-3/4 inch).
The signal from the camera is transmitted to a 1
9-inch TV monitor in the control room. The current range of visual indication provided by the camera system is limited to 16 inches from the camera's center of focus.
The camera system is to be modified to provide visual indication in the control room over a range of at least 64 feet 1-3/4' inches to J
-59 feet 6 inches.
The modification is to be completed during the 1989 Refueling Outage.
3.
In addition to the local standpipes and the TV monitoring system, an electronic level transmitter is connected to the RCS Flow Transmitter FT-435 tubing run.
The signal is recorded on a chart recorder and reads out on a level indicator (LIS-1040) that is provided with adjustable setpoint alarms that the operator sets to ensure RV level is maintained within the desired range.
Due to the fact that this system is only in service during plant operating Modes 5 and 6, a portable cabinet, designated CO2A, has been designed to house the monitor and icvel indicator.
CO2A sets on control panel CO2 when in use. This design places the level indicating equipment in one centralized location on the control operators console.
l The level indicating system is designed for operation in a borated water system with the maximum pressure being 100 psia and maximum temperature of 400*F.
By procedure, the system is calibrated and
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inspected for leakage when being placed into service prior to draining t
the RCS in Modes 5 and 6.
5 Status Update This task was completed prior to conducting reduced inventory operations during the 1989 Refueling Outage.
The upgraded Shutdown Reactor Vessel Level Indication System performed well during the 1989 Refueling Outage.
WRC RECOMMENDATION NO. 5 Implement procedures and administrative controls that generally avoid operations that deliberately or knowingly lead to porturbations to the RCS and/or to systems that are necessary to maintain the RCS in a stable and controlled condition while the RCS is in a reduced-inventory condition.
If operations that could perturb the RCS or systems supporting the RCS must be conducted while in a reduced-inventory condition, then additional measures should be taken to assure that the RCS will remain in a stable
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I Document Control Desk f
l Trojan Nuclear Plant Docket 50-344 Attachment A License NPF-1 March 30, 1990 i
page 6 of 8 i
Response
and controlled condition.
Such additional measures include both preven-tion of a loss of DHR and enhanced monitoring requirements to ensure timely response to a loss of DHR should such a loss occur.
In May 1984 Trojan experienced a loss of RHR cooling due to vortexing at the pump suction [ Licensee Event Report (LER) 84-10. Revision 11 The analysis of the root causes of this event prompted PCE to review carefully the drain-down process, instrumentation required, and previous knowledge gained through operating experience.
This review resulted in both system modifications and procedure revisions that were fully implemented during the 1986 Refueling Outage.
The following is a list of procedural and administrative controls that have or will be implemented by PCE to both prevent a loss of DHR and enhance monitoring requirements.
1.
The approval of a Senior Reactor Operator is required prior to beginning any work during maintenance outages. The purpose of this review is to ensure that equipment required in Modes 5 an3 6 is operable.
2.
Shif t Supervisor approval is required for evolutions, such as operating tests or instrunent calibrations, that may result in the unavailability of the RHR System until the reactor has been shut down greater than 10 days. By procedure, the Shift Supervisor must consider the decay heat load, the duration of the evolution, and the available backup decay heat removal methods prior to granting permission for such testing.
3.
Plant procedures will be revised to generally prohibit operations that deliberately or knowingly lead to perturbations to the RCS and/or to systems that are necessary to maintain the RCS in a stable and controlled condition while the RCS is in a reduced inventory condition.
Any evolutions that porturb the RCS will be preplanned, with operator actions for enhancud monitoring and timely renponse clearly stated.
Status Update This task was completed prior to conducting reduced inventory operations during the 1989 Refueling Outage.
NRC RECOMMENDATION No. 6 Provide at least two available* or operable means of adding inventory to the RCS that are in addition to pumps that are a part of the normal DHR
- Available means ready for uso quickly enough to meet the intended functional necd.
l Trojan Nuclear plant Document Control Desk Docket 50-344 Attachment A License NPF-1 March 30, 1990 page 7 of 8 systems.
These should include at least one high-pressure injection pump. The water addition rate capable of being provided by each of the i
means should be at least sufficient to keep the core covered, procedures for use of these systems during loss of DMR events should be provided.
The path of water addition must be specified to assure the flow does not bypass the RV before exiting any opening in the RCS.
Response
The instructions for draining the RCS and responding to a love of RHR are currently contained in several plant Operating Manual procedures.
All applicable instructions will be incorporated into a single proco-dure prior to April 1, 1989. The procedure will include the following:
y 1.
A requirement to provide at least two available* or operational means of adding inventory to the RCS that are in addition to pumps that are a part of the normal DHR systems. At least one source will be a high-pressure injection system pump.
The procedure will provide guidance on how to determine and specify a path of water addition that assures the flow does not bypass the RV before exiting any opening in the RCS.
r 2.
Specific instructions on when and how to initiate flow and maintain RV level.
3.
A weekly surveillance requirement to verify acceptable water addition flow paths that ensure the rates for each source are sufficient to remove decay heat and keep the core covered. The surveillance requirements will verify that the flow paths selected do not bypass the reactor vessel before exiting any opening in the RCS.
ptatus Update Rather than incorporate all instructions into a single procedure, PCE developed a governing procedure [ General Operating Instruction (GOI)-12. " plant Operations-Reactor Coolant System Reduced Inventory and Recovery from Refueling") to coordinate use of the existing procedures used for draining the RCS, and responding to a loss of RHR.
This approach is more consistent with the general format of the Plant Operating Manual. GOI-12 was implemented prior to conducting reduced inventory operations during the 1989 Refueling Outage.
NRC RECOMMENDATION NO. 7 Applicable to Westinghouse and Combustion Engineering NSSS designs.
Implement procedures and administrative controls that reasonably assure
- Available means ready for use quickly enough to meet tho intended functional need.
Trojan Nuclear plant Document Control Desk
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Docket 50-344 Attachment A License NPF-1 March 30, 1990 page 8 of 8 that all hot less are not blocked simultaneously by nozzle dams unless a vent path is provided that is large enough to prevent pressurization of the upper plenum of the RV.
Response
PGE will include precautions and controls in the RCS drain down procedure to ensure the recommendations listed above are complied with prior to the next scheduled drain-down during the 1989 Refueling Outage.
Status Update This task was completed prior to conducting reduced inventory operations during the 1989 Refueling Outage.
NRC RECOMMENDATION NO. 8 Applicable to NSSSs with loop stop valves. Implement procedures and administrative controls that reasonably assure that all hot legs are not blocked simultaneously by closed stop valves unless a vent path is provided that is large enough to prevent pressurization of the RV upper plenum og unless the RCS confi&uration prevents RV water loss if RV pressurization should occur. Closing cold legs by nozzle dams does not meet this condition.
Response
Not applicable; Trojan does not have loop stop valves.
Status Update No change.
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Trojan Nuclear plant Document Control Desk Decket 50-344 Attachment B License WpF-1 March 30, 1990 page 1 of 15 f
PORTLAND CENERAL ELECTRIC COMPANY (pCE)
RESPONSE TO pkOGRAMMED ENHAWCEMENTS IDENTIFIED IN CENERIC LETTER 88-17 NRC RECONNENDATION No. 1 Instrument ation Provide reliable indication of parameters that describe the state of the Reactor Coolant System (RCS) and the performance of systems normally used to cool the RCS for both normal and accident condi-tions. At a mininum, provide the following in the control rooms a
(a) Two independent RCS level indications.
(b) At least two independent temperature measurements representative of the core exit whenever the reactor vessel (RV) head is located on top of the RV (we suggest that temperature indications be provided at all times).
(c) The capability of continuously monitoring decay heat removal (DHR) system performance whenever a DHR system is being used for cooling the RCS.
(d) Visible and audible indications of abnormal conditions in temperature, level, and D:R system performance.
Response
(a) RCS Level.
The Shutdown Reactor Vessel Level Indication System provides indication of vessel level during Plant Operating Modes 5 and 6 to the operators in the control room.
The level indicating system meets NRC criteria by providing two independent level indications in the control room. The system consists of two l
separate tubing / standpipe designs which include RCS taps at RCS Flow Transmitters FT-425 (Crossover Leg Loop B) and FT-435 (Crossover Leg Loop C), and two 25-foot-long tempered glass t
I standpipes, with vent paths to the pressurizer spray vent line and pressurizer sampling system vent line, respectively. The reliability of each level gauge is enhanced by opening the equalizing valves for FT-425 and FT-435 so that each level gauge has two taps into the RCS crossover leg at the loop flow elbow.
This reduces the likelihood of flow blockages. The system l
provides the following means for monitoring RCS level:
1.
Remote (inside Containment) visual indication of RV level from the 55-foot elevation to 80-foot elevation.
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Trojan Nuclear plant Document Control Du1k Docket 50-344 Attachnent B License NpF-1 March 30, 1990 page 2 of 15 2.
A camera mounted inside containment can be focused on the standpipes (LG-1040B and.4040C) at RCS loop centerline (60 feet 1-3/4 inch).
The signal from the camera is transmitted to a 9-inch TV monitor in the control room. The current range of visual indication provided by the camera system is limited to 16 inches from the camera's conter of focus. The camera cystem will be modified to provide visual i
indication in the control room over a range of at least 64 feet 1-3/4 inches to 59 feet 6 inches and to allow in-Containment adjustment of the camera's mounting elevation so that the indicated level can be viewed from at or near 90 degrees to reduce parallax distortion in the video image.
This modification will be completed during the t
1989 E.; fueling Outage.
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3.
In addition to the local standpipes and the TV monitoring system, an electronic level transmitter is connected to the RCS Flow Transmitter FT A35 tubing run.
The transmitter output is recorded on a chart recorder and reads out on a level indicator (LIS-1040) that is provided with adjustable setpoint alarms that the operator sets to ensure RV level is maintained within the desired range.
This level instrumentation system was developed in rt sponse to an event that occurred at Trojan in May 1984, when a 3.oss of Residual Heat Removal (RHR) cooling was experienced di e to vortexing at the pump suction (Licensee Event Report (LER) 84-10 Revision 1).
The analysis of the root causes of this event prompted PCE to conduct a thorough review of the drain-down process, the instrumentation required, and previous knowledge gained through operating experience.
The following procedural guidance has also been provided to ensure the operator is fully aware of the actual RV levels 1.
Procedures contain a table of critical levels associated with draining the RCS.
2.
Guidance is provided to alert the operator of RV water levels and RHR system flows at which vortexing is likely to occur.
3.
Procedural requirements provide for both the pressurizer and RV head vent to be open for maximum vent capability.
4 pGE recognizes that the drainage rate may exceed the vont capacity; therefore, several holdpoints have been estab-lished to ensure level indication is not significantly affected by differing pressures in the RCS vent spaces (reactor head and pressurizer vapor space).
The use of a pressurizer vent filter will be discontinued, promoting
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Trojan Wuclear plant Docur..ent Control Desk i
Docket 50-344 Attachment B License NpF-1 March 30, 1990 page 3 of 15 equalised RCS venting between the reactor head and pressur-l izer vapor space, and thus reduce level differences due to
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pressure differe;.cos.
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Level indications are closely monitored during draining operations. Under twisting procedures, if Loops B and C gaute glass indications disagree by greatsr than 2 inches, or gauge glass indication to level transmitter indications disagrees by greater than 3 inches, the draining is stopped until the cause of the disagreement has been resolved.
6.
The level instrumentation is initially placed in service i
when the RCS is in a cold shutdown, vented condition.
The level transmitter is calibeated while a stable pressuriser level of 10 to 15 percent exists.
This allows verification that the drain-down level transmitter in the control room is properly tracking level decreases when they are resumed.
7.
The gauge glasses are rhocked once per shift for air bubbles or leaks which could indicate a faulty indicating system.
8.
The operators are cautioned that RCS gauge glasses may not accurately reflect the level in all portions of the RCS.
Level differences may exist due to fluid momentum and density variations or gas-exerted pressures in portions of the RCS.
The level instrumentation will remain functional during RHR nystem upsets that may occur during cold shutdown RHR operation.
(b) RCS Temperature.
Two independent, continuous temperatu:le indications are utilized that are representative of the core exit conditions. The Rt!H system temperature indication is the principal means for moni-toring temperature under drained and vented system conditions.
However, should the RHR system fail to function, the in-core exit thermocouples remain functional and are a valid indication of the RV/ core temperature. A minimum of two in-core exit thermocouples are kept in service and can be monitored from the cuntrol room whenever the RCS is drained 3 feet below the RV flunge.
The in-core exit thermocouples are battery-backed nources of temperature indication. At least two in-core thermocouples are connected in a drained-down condition. The thermocouples are only disconnected immediately prior to lif ting the RV head and are reconnected as soon as possible after ressating the RV head during refueling operations. Administratively controlling the 1
1 Trojan Nuclear plant Document Control Desk i
Docket 50-344 Attachment B License NFF-1 March 30, 1990 page 4 of 15 operability of the in-core exit thermocouples reduces the time frame to an absolute minimum in Which RHR temperature indication is the solo source of temperature information.
A situation involving both the removal of the RV head and oper-sting at a reduced RV level is unlikely because radiation expo-sure due to this mode of operation would preclude access to a major portion of Containment.
The only time the core exit temperature indication would be unavailable is When the RV head is removed. When the head is removed, the refueling cavity is being filled (or drained), or is filled with 23 feet of water available above the core. This large amount of water acts as a sufficient heat sink to provide cooling to the core and lessens the need for independent temperature measurement.
(c) RHR System performance.
The following RHR System information is available to the oper-ator in the control room:
- RHR Flow (Indication)
- RHR Pump Amperage (Indication)
- RHR Pump Discharge pressure (Indication)
- RHR Pump Suction Pressure (Indication)
- RHR Heat Rxchanger Inlet / Outlet Temperature (Indicated and Recorded)
The RHR pump suction and discharge pressure transmitters and RHR heat exchanger inlet and outlet temperature indicators have inputs to the plant computer from which alarms could be gene-rated.
RHR pump amperage could also be easily connected to a recorder with alarm capability. PGE will develop and implement the methods for integrating the use of these alarms to aid in early identification of RHR pump vortexing.
These a$ditional means of monitoring RHR system performance will be etaluated during the 1989 Refueling Outage, with any permanent means implemented prior to the 1990 Refueling Outage.
(d) Visible and Audible Abnormal Condition Indication.
I As previously stated in Items (a), (b), and (c) above, pGu provides or will provide the operator with visual indication and alarm capabilities for RCS level and temperature, as well as RHR L
pump suction and discharge pressure and pump amperage. This combination of alarms, indications, and procedural guidance provides the operator with sufficient information to ensure reliable operation of the DHR system.
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i Trojan Nuclear Plant Document Control Desk Docket 50-344 Attachment B Liewn=e NPF-1 March 30, 1990 Page 5 of 15 Status Update (a) RCS Level.
The tasks to upgrade the camera system and venting for the Shutdown Reactor Vessel Level Indication System were completed during the 1989 Refueling Outage.
(b) RCS Temperature.
This task was completed prior to conducting reduced inventory operations during the 1989 Refueling Outage.
Temporary disconnection of the in-core exit thermocouples is minimized in duration and limited to conditions in which preparation for reactor vessel head movement during reduced inventory conditions requires temporary disconnection.
(c) RHR System Performanco.
An evaluation was initiated during the 1989 Refueling Outage of generating alarms from signals of RHR pump suction and discharge pressure, RHR heat exchanger inlet and outlet temperature, and RHR pump amperage, that along with existing alarms will aid in early identification of RHR pump vortexing. As a result of this evaluation, actions are being implemented to supplement existing control room indications. Provisions f or visible and audible indication of an abnormal condition as well as trending capabilities will be available prior to reduced inventory operations during the 1990 Refueling Outage for the following parameters:
1.
A and B RHR pump motor current.
2.
A and B RHR pump suction and discharge pressure.
1 3.
A and B RHR heat exchanger inlet and outlet temperature.
I (d) Visible and Audible Abnormal Condition Indication.
As stated in (a), (b), and (c) above, visible and audible abnormal condition indications have been provided for RCS level i
and RCS temperature and will be provided for RHR system performance prior to reduced inventory operations during the 1990 Refueling Outage.
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Procedure changes will be completed to set appropriate computer alarm values for each of these parameters prior to reduced inventory operations during the 1990 Refueling Outage.
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Trojan Nuclear plant Document Control Desk I
Docket 50-344 Attachment B License NpF-1 March 30, 1990 Page 6 of 15 NRC RECOMNgNDATTON NO. 2 procedures l
Develop and implement procedures that cover reduced inventory oper-ation and that provide an adequate basis for entry into a reduced inventory condition.
These includes (a) procedures that cover normal operation of tt.) Nuclear Steam Supply System (NSSS), the Containment, and supporting systems under conditions for Which cooling would normally be provided by DHR systems.
(b) procedures that cover emergency, abnormal, off-normel, or the equivalent operation of the NSSS, the Containment, and support-ins systems if an off-normal condition occurs While operating under conditions for which cooling would normally be provided by DHR systems, t
(c) Administrative controls that support and supplement the proco-dures in Items (a), (b), and all other actions identified in this communication as appropriate.
Response
(a) Normal Operation.
Operating Instruction (01)-3-2, Draining the RCS, provides the guidance and basis for entering into a reduced inventory condi-tion.
This procedure. When utilized with other system operating instructions, assures operability of the RHR function.
It is recognized that using more than one procedure to accomplish a single task could contribute to operator confusion and over-sight.
Therefore, all instructions for operating the RCS in a reduced inventory condition will be incorporated into a single procedure. This procedure will also provide specific instruc-tions for identifying system conditions that require entry into off-normal instructions.
This procedure change will be completed prior to mid-loop operation during the 1989 Refueling Outage. Also, the administrative controls for maintaining and restoring Containment closure during RCS reduced inventory operetion will be reviewed and enhanced prior to reduced inven-Lory operation during the 1389 Refueling Outage.
(b) Off-Normal Instructions (ONIs) and Emergency procedures.
ONI-13, Malfunction of Residual Heat Removal Loop, and ONI-47, Backup Core Heat Removal With Open RCS, provide instructions for the actions to be taken in the event of a failure of the oper-ating RHR loop, and for core heat removal with the RCS open and both RHR pumps unavailable, respectively. These proceduren will
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Trojan Nuclear plant Document Control Desk Docket 50-344 Attachment B License NpF-1 March 30, 1990 l
page 7 of 15 be combined into a single procedure.
This procedure will f
provide specific instructions for identifying system conditions l
that require entry into Emergency Procedures. This procedure change will be completed prior to the 1990 Refueling Outage, i
Additionally, rapid Containment closure prior to or during core boiling after a loss of RHR cooling will be addressed as part of the containment closure administrative controls that will be implemented prior to reduced inventory operation during the 1989 Refueling Outage.
PGE is participating in Westinghouse Owners Group (WOG) activi-ties for the development of guidance and background documents for the preparation of plant-specific procedures for dealing with a loss of RHR cooling flow (completion scheduled for f
October 10, 1989).
pGE will implement emergency procedures which incorporate the WOG guidance and background documents during the 1990 Refueling Outage.
(c) Administrative Controls.
e The following administrative controls support and supplement the procedures in Items (a), (b), and all other actions identified in this letter as appropriate:
- Administrative Order (AO)-3-11, Containment Access and Evacuation, provides the administrative control to ensure modified Containment integrity can be established prior to core uncovery in the event forced RCS cooling is lost While in a condition with reduced RCS inventory. As mentioned above, this administrative control will be enhanced to address Containment closure prior to or during core boiling conditions after RHR cooling has been lost prior to reduced inventory i
operation in the 1989 Refueling Outage.
- A0-3-9 Maintenance Request, requires approval of a senior 3
reactor operator prior to beginning any work during mainten-ance outages. This approval helps ensure that equipment required in Modes 5 and 6 is operable.
- A0-3-14, Safety-Related Outages, assures the availability of mode-related components required by Technical Specifications.
This procedure providos the operator with the controle needed to assure essential safety-related equipment is operational.
With the RCS drained to a reduced inventory condition, this procedure would preclude the removal from service of train-related equipment necescary for supporting the RHR function.
- Operating Instruction (01)-3-2, Draining the RCS, requires shift supervisor's approval for evolutions such as operating tests or instrument enlibrations that may result in the unavailability of the RHR system until the reactor has been
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c Trojan Nuclear plant Document Control Desk Docket 50-344 Attachment B License NpF-1 March 30, 1990 page 8 of 15 i
shutdown longer than 10 days. By procedure, the shift super-visor must consider the decay heat load, the duration of the evolution, and the available backup decay heat removal methods.
l In addition, plant testing and maintenance procedures will be revised to generally prohibit operations that deliberately or knowingly lead to perturbations to the RCS and/or to systems that are necessary to maintain the RCS in a stable and con-trolled condition. Any evolutions with the potential to perturb the RCS will be proplanned with operator actions for enhanced monitoring and timely response clearly stated. Necessary procedure changes will be completed prior to reduced inventory conditions during the 1989 Refueling Outage.
Status Update (a) Normal Operation.
These tasks were completed prior to conducting reduced inventory operations during the 1989 Refueling Dutage with the following clarification:
Rather than incorporate all instructions into a single procedure, PGE developed a governing procedure [ General Operating Instruction (GOI)-12, " Plant Operations-Reactor Coolant System Reduced Inventory and Recovery from Refueling")
to coordinate use of the existing procedures used for draining the RCS, and responding to a loss of RHR.
This approach in more consistent with the general format of the plant Operating Manual.
(b) Off-Normal Instructions (ONIs) and Emergency procedures.
The procedure for Containment closure was implemented prior to conducting reduced inventory operations during the 1989 Refueling Outage. The procedure combining ONI-13 and ONI-47 into a single procedure is written and currently in routing for approval. This procedure will be implemented prior to conducting reduced inventory operations during the 1990 Refueling Outage. Emergency procedures Which incorporate WOG guidance have not been developed.
The WOG effort supporting these emergency procedure changes is scheduled to be completed on March 30, 1990. Pending completion of this WOG effort, PCE will incorporate appropriate information from the guidance in applicable procedures prior to the 1991 Refueling Outage.
(c) Administrative Controls.
These tasks were completed prior to conducting reduced inventory operations during the 1989 Refueling Outage.
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Trojan Nuclear plant Document Control Desk Docket 50-344 Attachment B License NPF-1 March 30, 1990 page 9 of 15 NRC RECONNENDATION No. 3 t
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[gulpment (a) Assure that adequate operating, operable, and/or available equipment of high reliability is provided for cooling the RCS and for avoiding a loss of RCS cooling.
(b) Maintain sufficient existing equipment in an operable or available status so as to mitigate loss of DHR or loss of RCS inventory should they occur. This should include at least one highpressure injection pump and one other system. The water addition rate capable of being provided by each equipment item i
should be at least sufficient to keep the core covered.
(c) provide adequate equipment for personnel communications that involve activities reisted to the RCS or systems necessary to c.
maintain the RCS in a stable and controlled condition.
Response
(a) Equipment Reliability.
The equipment utilized for cooling the RCS and avoiding a loss of cooling is highly reliable. The pungs, valves, and instru-mentation are predominantly engineered safety features (ESF) equipment that is emergency-diesel-generator-backed. The likelihood of inadvertent loss of RHR capability is further reduced by system level and temperature alarms that alert the operator to unexpected changos.
Spurious operation of the RHR suction valves is prevented by placing the valve controls in
" lockout". This switch configuration prevants autoclosure of the valves, but maintains the operator's ability to close the valves if required.
Offsite Power Sources, Emergency Diesel Generators, Electrical Distribution systens, Component Cooling Water, Service Water, and Residual Heat Removal are the major systems whose oper-ability is required to provide decay heat removal. All these systems have Technical Specifications requiring operability in all modes. In addition, pCE requires equipment in the same ESF train to be considered operable for a system to be operable.
pGE will investigate several options for enhancing equipment reliability. They include (a) omitting the RHR suction valve interlock, (b) Technical Specification changes to reduce RHR flow rates when core cooling requirements can be met at a lower rate, and (c) procedural flexibility that links heat-up rate and RCS configuration to both the RHR operational requirements and the operability and availability of backup cooling equipment.
Theco items will be added to the "RCS Mid-Loop Action plan",
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Trojan Nuclear plant Document Control Desk Docket 50-344 Attachment B l
License NPF-1 March 30, 1990
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page 10 of 15 q
l which has been developed to track actions required by this letter, and be resolved prior to the 1990 Refueling Outage.
(b) Equipment Operability.
PCE has agreed to ensure sufficient equipment is maintained in an operable or available status so as to mitigate the loss of l
RHR or loss of inventory should they occur by committing to the following procedure changes in PGE to NRC letter dated January 16, 1989, " Response to Generic Letter 88-17, I.oss of Decay Heat Removal (DHR)":
1 1.
A requirement to provide at least two available or opera-
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tional means of adding inventory to the RCS that are in i
addition to pumps that are a part of the normal RHR systems. At least one source will be a high-pressure safety injection pump. The procedure will provide guidance on how to determine and specify a path of water addition that assures the flow does not bypass the RV before exiting any opening in the RCS.
2.
Specific instructions on when and how to initiate flow and maintain RV level.
3.
A weekly surveillance requirement to verify acceptable water addition flow paths that ensure the rates for each source are sufficient to remove decay heat and keep the core covered. The surveillance requirements will verify that the flow paths selected do not bypass the reactor vessel before exiting any opening in the RCS.
In addition PGE will evaluate the measures necessary to use the steam generators for cooling following a loss of RHR.
These i
measures will be evaluated in the "RCS Mid-Loop Action Plan".
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Gravity makeup from storage tanks is already included in Plant procedures. However, guidance on RCS pressure limitations will be provided as a program enhancement.
All evaluations and procedure changes will be completed prior to the 1990 Refueling Outage.
(c) Communications.
All operations necessary to maintain the RCS in a stable and controlled condition can be accomplished from the control room.
In the event in-plant operation of equipment becomes necessary, the operators have the in-Plant phone system and radios, t
Trojan Nuclear Plant Document Control Desk Docket 50-344 Attachment D n
License NpF-1 March 30, 1990 Page 11 of 15 i
Status Update (a) Equipment Rollability.
I T
The tesk to specify procedural flexibility for using available backup cooling equipment, in responso to a loss of RHR for various RCS configurttions during RCS reduced inventory, was completed prior to conducting reduced inventory operations f
during the 1989 Refueling Outage. Periodic Operating Tout (POT) 2-8, "ECCS Equipment Availability for Reduced RCS Inventory", is the procedure that accomplishes this task.
The Safety Evaluation by the Office of Nuclose Reactor Regulation relating to Removal of Auto Closure Interlock Punction, Westinghouso Owners Group WCAP-11736. Volumes I and II, stated in Section 2.6, that licensees should do sufficient Probabilistic Risk Assessment (PRA) and safety
(
analyses to ensure that its plant will not show results that will invalidate the conclusions of WCAP-11736.
PCE received WCAP-11736 in November 1989 and has not performed PRA and safety analyses work to assess if its results are valid for Trojan.
PCE is performing a PRA for Trojan in responso to NRC Generic Letter 88-20. " Individual Plant Examination for Severo Accident vulnerabilities".
The results from this effort are due to be submitted to the NRC by September 1, 1992.
PGE will assess deletion of the RHR suction valvo autoclosure interlock as part of the Trojan PRA offort. This assessment will determine if the the WCAp-11736 results are valid for Trojan.
If it is shown that deletion of the RHR suction valvo autoclosuro interlock is appropriate for Trojan, this change will be implomonted using the WCAP-11736 guidance prior to conducting reduced inventory operations during the 1994 Refueling Outage.
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The task to apply for a Technien1 Specification change to allow reduced RHR flow ratos when core cooling requirements can be mot at a lower flow rate will not be performed.
Technical Specifications already allow reducing RHR flow rates in Modo 5 (cold shutdown).
RHR flow rate of at least 3,000 gpm is required in Mode 6 (refueling) to minimiro the offect of a boron dilution incident and prevent boron stratification. Most RCS reduced inventory conditions occur in Mode 5.
Evolutions that involvo substantial reductions in RCS inventory, such as mid-loop, are most likely to occur in Modo 5 or when defuelod; therefore, a Technical Specification change to allow reduced RHR flow rates will not be submitted.
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Trojan Duclear plant Document Control Desk Docket 30-344 Attactment B License Wyr-1 March 30, 1990 page 12 of 15 (b) Equipment Operability.
Eve 14ation of measures for using steam generators for cooling after a loss of RHR will be performed pending receipt of the final WOG guidance for emergency procedures prior to the 1991 Refueling Outage. RCS pressure limitations for gravity makeup from storage tanks has been specified in POT 2-0.
The remainder of these tasks were completed prior to conducting reduced inventory operations during the 1989 Refueling Outage.
(c) Communleations.
This task was completed prior to conducting reduced inventory operations during the 1989 Refueling Outage.
WPC RgColgtENDATION WO 4 Analytig Conduct analyses to supplement existing information and develop a basis for procedures, instrumentation installation and response, and equipment /NSSS interactions and response.
The analyses should encompass thermodynamic and physical (configuration) states to which the hardware can be subjected and should provide sufficient depth that the basis is developed.
Emphasis should be placed upon obtain-ing a conglete understanding of NSSS behavior under nonpower operation.
Response
PGE has developed curves to provide the operator with heat-up rate information and time nergins for core boiling and core uncovery when operating in the drained-to-the-hot-leg centerline condition. proco-dures also contain guidance to alert the operator to reactor vessel water levels and RHR flows at which vortexing is likely to occur.
Safe indicated RCS level, combined with safe RHR flow rate under typical refueling conditions, have been established by operating experience. Any nonconservative changes to these established " safe" conditions will be thoroughly evaluated and incorporated into the appropriate plant procedure prior to operating in thoso conditions.
PGE will include the review of the Westinghouse Owners Croup analysis in the "RCS Mid-Loop Action plan".
This review will be focused on improving the basis for operator training and procedural guidance in the following areas:
I Trojan Nuclear plant Document Control Desk Docket S0-344 Attactment B License NPF-1 March 30, 1990 page 13 of 1S
- 1) Heat-up rate, time to saturation, mawinum pressurisation, effect of water in steam generators, vapor venting, liquid venting, and time to core uncovery.
(b) Influence of steam generator nor:1e dams.
(c) Mitigation actions, including gravity makeup to the RCS, use of steam generators, saf ety injection, and feed and bleed.
(d) Understanding of behavior during nonpower operation involves level instrusentation. Areas that will be considered include response times, RRR air entrainnent, RHR flow rate, draining location and rate, range (RCS connection location and inpact upon instrunentation indication), and RCS level (such as poten-tial for error due to a hot-les level high enough to block the pressuriser surge line connection to the RCS, or the influence of a full hot-leg due to inability of air spaces to conmunicate).
These actions will be incorporated into plant training and operating procedures prior to reduced inventory operation during the 1990 Refueling Outage.
Status Update These tasks were congleted prior to conducting reduced inventory operations during the 1989 Refueling Outags, using information available at that time, pending receipt of additional WOG information, such as emergency procedure guidance, additional operator training and procedural guidance will be provided as appropriate.
NRC RECOMMENDATION Wo. 5 Technical Specifications Technical Specifications that restrict or limit the safety benefit of the actions identified in this letter should be identified and appropriate changes should be submitted.
Rt.gponse pct will address Technical Specification changes while completing the consnitments made in the preceding sections of this letter.
Technical Specification changes will be made with the intent of enhancing the reliability of the decay heat removal function, while striving to simplify the Technical Specifications in general.
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Trojan Nuclear plant Document Control Desk Docket 50-344 Attachment t License NFF-1 March 30,1990 page 14 of 15 A License Change Application will be submitted for those changes considered to enhance safety prior to the 1990 Refueling Outage.
[17tus Update Technical specification changes necessary to enhance reliability of the decay heat removal function have not been identified.
If any such introvements are identified, then Technical specification changes will be submitted as appropriate.
NBC.RgCOMMENDATION WO. 6 BCS perturbations Item 2.5 of the expeditious actions should be reexamined and opera-tions refined as necessary to reasonably minimise the likelihood of loss of DHR.
Effronpt p0E will review plant testing and maintenance activities to identify those evolutions which pose a threat to reliable operation of the systems required for decay heat removal. When feasible, testing and maintenance procedures will be changed to reduce the likelihood of affecting RHR operation or will be revised to require completion during periods when decay heat is low. When naintenance or testing activities must be conducted during periods of high decay heat, procedures will be revised to require preplanning of the evolution with operator actions for enhanced monitoring and tinely response clearly stated. Necessary procedure revisions will be inglemented prior to the 1990 Refueling Outage.
Status Update This twsk was completed prior to conducting reduced inventory operations during the 1989 Refueling Dutage. Additionally, pCE has established a work control group with responsibilities for coordinating and prioritizing work activities, including preparation of clearances and tags and reviewing work constraints.
In preparation for reduced inventory operations, particular attention is given tot (a) Containment closure requirements.
(b) Boration flow path.
(c) RCS cooling and makeup capability.
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t Trojen Nuclear Plant Document Control Desk Decket 50-344 Attachment B License WPF-1 March 30, 1990 Page 15 of 15 l
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(d) 1horough planning to avoid RCS and RMR system perturbations.
i This work control group is in piece for the 1990 Refueling Outage.
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