ML18153B574
| ML18153B574 | |
| Person / Time | |
|---|---|
| Site: | Surry, North Anna, 05000000 |
| Issue date: | 01/06/1989 |
| From: | Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| 88-737, GL-88-17, NUDOCS 8901200417 | |
| Download: ML18153B574 (13) | |
Text
...
e e
VIRGINIA ELECTRIC AND POWER COMPANY RICHMOND, VIRGINIA 23261 W. R. CARTWRIGHT VxcE PRESXDENT NUCLEAR January 6, 1989 U. S. Nuclear Regulatory Commission Attn:
Document Control Desk Washington, D.C.
20555 Gentlemen:
VIRGINIA ELECTRIC AND POWER COMPANY SURRY POWER STATION UNITS I AND 2 NORTH ANNA POWER STATION UNITS I AND 2 RESPONSE TO GENERIC LETTER 88-17 LOSS OF DECAY HEAT REMOVAL Serial No.88-737 NO/SEC-LIC:jmj Docket Nos.
50-280 50-281 50-338 50-339 License Nos. DPR-32 DPR-37 NPF-4
- NPF-7 Virginia Electric and Power Company has received and reviewed Generic Letter 88-17, Loss of Dec av Heat Removal, dated October 17, 1988 which i dent i fi ed eight recommended expeditious actions and six recommended programmed enhancements to reduce the incidences of loss of decay heat removal during non-power operation.
Licensees were requested to provide, within 60 days of receipt, plans for implementing the eight expeditious recommendations.
We have also received and reviewed the Thomas E. Murley letter dated December 2,
. 1988 on the Loss of Decay Heat Removal.
We recognize the consequences of these events and have been taking timely actions to enhance the reliability of the Residual Heat Removal Systems (RHR) and thereby reduce the likelihood of a loss of decay heat removal event from occurring at the North Anna and Surry Power Stations.
To facilitate these efforts, Virginia Electric and Power Company is participating in the Westinghouse Owners Group's efforts to develop a generic action plan to enhance RHR reliability and to mitigate the effects of a loss of RHR function.
The knowledge obtained from these efforts is reflected in our plant specific action plans.
Descriptions of the specific actions being taken to implement each of the eight expeditious recommendations at North Anna and Surry Power Stations are provided in the Attachment.
These will be fully implemented at the appropriate stations prior to the next refue 1 i ng outage or the next outage requiring reduced inventory conditions, which ever occurs first.
The schedule for implementation of the six programmed enhancements for both North Anna and Surry will be submitted by February 3, 1989.
If you have any questions or require additional information, please contact us.
Attachment:
cc:
U. S. Nuclear Regulatory Commission 101 Marietta Street, N.W.
Suite 2900 Atlanta, GA 30323 Mr. W. E. Holland NRC Senior Resident Inspector Surry Power Station Mr. J. L. Caldwell NRC Senior Resident Inspector North Anna Power Station
COMMONWEALTH OF VIRGINIA)
)
COUNTY OF HENRICO
)
The foregoing document was acknowledged before me, in and for the County and Commonwealth aforesaid, today by W. R. Cartwright who is Vice President -
Nuclear, of Virginia Electric and Power Company.
He is duly authorized to
- execute and file the foregoing document in behalf of that Company, and the statements in the document are true to the best of his knowledge and belief.
Acknowl~dg~d befo~e me this &J.7! day of ~/lAt~
, 19 ~-
My Com1mss1on expires:
i!+/-i, b&.... 0 "".j ZS., 19.5JL..
Notary Public
,."'"~
\\,
c (SEAL)
RESPONSE TO GENERIC LETTER 88-17 EXPEDITIOUS ACTIONS Generic Letter 88-17 Expeditious Actions The following expeditious actions should be implemented prior to operating in a reduced inventory condition:
- 1.
Training Discuss the Di ab lo Canyon event, related events, lessons learned, and implications with appropriate plant personnel.
Provide training shortly before entering a reduced inventory condition.
Response
The Diablo Canyon event has been discussed in detail with operations personnel during Licensed Operator Requa l i fi cation Program
( LORP) training.
The LORP training included the initial plant status, system indications, actions taken, and lessons learned from the loss of decay heat removal event.
The training was performed during LORP cycles in 1988 and was completed by May 20, 1988 at both stations.
In addition to the Diablo Canyon event training, plant specific detailed mid-loop operation training will be sch~uled and presented during LORP cycles prior to future refueling outages. Station management will have direct involvement in the initial mid-loop training to ensure staff sensitivity is elevated when operating in a reduced inventory condition.
Training for cooldown/draindown operations will include the following:
- 1) RCS cooldown
- 2) RCS draindown
- 3) RHR System Operation and Malfunctions
- 4) Plant operations with reduced RCS inventory
- 5) NRC Generic Letter 88-17 requirements
- 6) Diablo Canyon event
- 7) Related utility events
- 8) NAPS Loss of Inventory event (June 1987)
- 10) Surry RHR System Event (Sept. 1988)
- 11) Review of abnormal procedures
- 12) Simulator training Prior to performing any reduction in reactor vessel
- level, the controlling procedure for draining the Reactor Coolant System will require a pre-job briefing with involved shift personnel.
- Prior to the current refueling outage at Surry Unit 2, personnel involved in plant o_perations were provided detailed plant specific training based on WOG recommendations and information available on the then forthcoming Generic Letter 88-17 requirements.
This training included classroom and simulator instructions which covered most of the items listed above.
Station management was involved in this initial training as described.
- l -
~I
- 2.
Containment Closure Implement procedures and administrative controls that reasonably assure that containment closure will be achieved prior to the time at which core uncovery could result from a loss of DHR coupled with the inability to initiate al tern ate cool i ng or addition of water to the, 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:
(a) prior to entering a reduced RCS inventory condition...
and should apply whenever operating in those conditions.
If such procedures and administrative controls are not operational, then either do not enter into the applicable condition or maintain a closed containment.
Response
Our emphasis is to maintain intact at least one boundary on containment penetrations during reduced inventory operations (water level lower than 3 feet below the vessel flange).
The controlling procedure for draining the reactor coolant system requires the status of the containment configuration to be established and verified procedurally, prior to entering a
reduced inventory condition.
Specific containment penetrations (i.e., equipment hatch, personnel hatch) may remain open to support outage activities during reduced inventory operation.
If specific penetrations are opened, a containment closure team will be established to take the necessary actions to reclose the containment in the event of a loss of decay heat removal.
The abnormal procedure for loss of RHR capability, directs containment closure action to be initiated and continued until the Residual Heat Removal (RHR) system is returned to service and core conditions are verified normal.
The closure team includes necessary maintenance and operations personnel and will be responsible for closing the equipment hatch, personnel hatch, and any other piping penetrations that were opened for maintenance.
The containment closure team members will be designated each shift and recorded in the Senior Reactor Operator Log in the control room.
Any equipment or tools required by the team to reclose the containment will be pre-staged and designated as containment closure material.
The closure team will be on site whenever the unit is in a reduced inventory condition and open containment penetrations are necessary.
(On Dec. 14, 1988, an abnormal condition occurred at Surry during the indexing procedure for the manipulator crane.
When the refueling SRO notified the Shift Supervisor, the closure team was called out.
Within 15 minutes of that notification, operators had the personnel access hatch closed and within 34 minutes, final containment closure was achieved with the closing of the equipment hatch.)
- 3.
RCS Temperature 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.
Temperature indication should be periodically checked and recorded by an operator or automatically and continuously monitored and alarmed.
Temperature monitoring should be performed either:
a) by an operator in the control room (CR), or b) from a location outside the containment building with prov1s1on for providing immediate temperature values to an operator in the CR if significant changes occur.
Observations should be recorded at an interval no greater than 15 minute during normal conditions.
Response
The controlling procedures for draining the reactor coolant system will be revised to ensure at 1 east two i ncore temperature indicators are operable prior to draining the RCS to a reduced inventory condition.
The incore temperature will continuously indicate in the control room and wi 11 be periodically monitored by the control room staff.
The temperature readings are periodically recorded on the control room shutdown logs by the control room operators.
When the RHR system is in operation, system temperature is also available and recorded via a strip chart on the main contra 1 board.
RCS temperature curves for heatup subsequent to a loss of RHR have been developed and incorporated into the abnormal procedure for loss of RHR capability.
- 4.
RCS Water Level Provide at least two independent, continuous RCS water level indications whenever the RCS is in a reduced inventory condition.
Water level indications should be periodically checked and recorded by an operator or automatically and continuously monitored and alarmed.
Water level monitoring should be capable of being performed either:
a) by an operator in the CR or, b) from a location other than the CR with prov1s1on for providing immediate water 1 eve 1 va 1 ues to an operator in the CR if significant changes occur.
Observations should be recorded at an interval no greater than 15 minutes during normal conditions.
Response
Surry and North Anna have one continuous means of level indication as allowed by the generic letter for expeditious actions.
The requirement for a second means of level indication is still under review.
Schedules and plans for implementation of engineering recommendations will be included in the responses to programmed enhancements.
SURRY Remote continuous level indication has been installed and placed in operation on Surry Unit 1 and is being installed on Surry Unit 2 during the current outage.
The design change consists of the installation of a magnetic flag indicator, hardpipe connected to the 'C' RCS loop. This will pro vi de a local means of indication in the containment.
A remote level indicator has been provided in the control room which continuously displays level to the operator and provides an alarm of loss of shutdown cooling level at an elevation of 12' 4".
To ensure reliable operation of the installed vessel level indication system, the standpipe isolation valves and vent valve will be administratively controlled open when the standpipe is placed inservice.
At present for Surry Unit 2, level indication is provided by a Tygon type standpipe installation with a television camera monitor to provide continuous standpipe indication in the control room.
No alarms are provided by this installation.
The standpipe level is periodically monitored by the control room operator and recorded every four hours.
NORTH ANNA North Anna will use a level hose with TV camera indication available in the control room during the 1989 refueling outages for remote RCS level indication.
The standpipe level will be periodically monitored by the control room operator and recorded every four hours.
e A design change will be implemented during the 1989 refueling outages to permanently install an RCS standpipe in containment to eliminate the need for the temporary level hose arrangement.
The permanent standpipe will be connected via spool pieces to the RCS piping prior to RCS drain down and removed before system pressurization.
Local level indication will be provided by a magnetic flag indicator mounted on the standpipe.
The present method of measuring the RCS level ( temporary tubing) wil 1 be available during the installation of the design change.
To ensure reliable operation, the standpipe isolation valves and vent valve will be administratively controlled open when the standpipe is placed in service.
A transmitter will be installed during the subsequent refueling outage to remotely provide RCS level indication in the control room.
e
- 5.
RCS Perturbation Implement procedures and administrative controls that generally avoid 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.
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 RCS will remain in a stable and controlled condition.
Such additional measures include both prevention of loss of DHR and enhanced monitoring requirements to ensure timely response to a loss of DHR, should such a loss occur.
Response
An operations procedure for assessing maintenance activities for potent i a 1 to cause a 1 oss of RCS inventory, has been deve 1 oped and implemented at North Anna and is being developed at Surry.
The procedure will increase the sensitivity of the operations and maintenance staff to events that may affect RCS inventory.
The shift supervisor will evaluate work to be performed against the assessment procedure.
If the work affects the reactor coolant, safety injection, residual heat removal, refue 1 i ng puri fi cation, or charging systems, the assessment procedure must be completed.
The procedure requirements are:
- 1.
If maintenance requires an opening on the co 1 d 1 eg during mid-1 oop operation, establish and verify a hot 1 eg vent path.
Ensure proper administrative controls are established to maintain the hot leg vent path until system integrity is restored.
- 2.
Conduct a pre-job briefing with maintenance personnel.
Discuss loss of inventory potential and contingency actions.
- 3.
Have an operator accompany maintenance personnel to positively identify the component and establish communications.
- 4.
Ensure makeup capability to the RCS is readily available.
- 5.
Establish communications between work site and control room.
- 6.
Notify the control room at the time work is started and when work is suspended.
- 7.
Monitor RCS level (standpipe, pressurizer level, cavity level, reactor vessel level) and containment sump level frequently during the process.
- 8.
Notify the control room when the component is closed and system integrity is restored.
The RCS draindown procedure requires an operator to remain in the containment to monitor RCS standpipe level and RHR pump operation during any planned reduction in the vessel water level.
A Senior Reactor Operator (SRO) assists the Planning Department in scheduling outage activities. Operations provides direct input into the schedule minimizing work on systems that could have an adverse effect on RCS inventory during reduced inventory operation.
Procedures for draining the Reactor Coolant System have been revised to perform the reactor vessel head purge before draining the RCS to a reduced inventory condition.
RCS inventory will be maintained at reactor vessel flange level during purge operations.
Prior to entering a reduced inventory condition, the controlling procedure ensures the primary system is vented with the pressurizer PORVs open to prevent overpressuri zat ion of the RCS.
Then the RHR suet ion valves are de-energized after they have been
- opened, to prevent inadvertent closure and subsequent loss of RHR capability.
A Shift Technical Advisor (STA) is required on each shift during all pl ant conditions including reduced RCS inventory operation.
The administrative procedure defining the STA responsibilities, will require RCS inventory to be monitored and documented once per shift by the STA.
The STA will immediately notify the Shift Supervisor of any significant loss of RCS inventory or unexpected changes in status.
The abnormal procedures for the loss of RHR functions have been reviewed and revisions made to improve its effectiveness.
The procedures address malfunctions of the RHR system and loss of RHR capability.
e
- 6.
RCS Inventory Addition Provide at least two available or operable means of adding inventory to the RCS that are in addition to pumps that are part of the DHR systems.
These should include at least one high pressure injection pump.
The water addition rate capable of being provided by each of the means should be at least sufficient to keep the core covered.
Procedures for use of these systems during loss of DHR events should be provided.
The path of water addition must be specified to ensure the flow does not bypass the reactor vessel before exiting any opening in the RCS.
Response
NORTH ANNA The procedure for draining the Reactor Coolant System has been revised to require one high head and one low head safety injection pump to be available prior to RCS draindown into a reduced inventory condition. The flow path and pump status will be verified by the shift turnover checklist.
The checklist specifies that the hot leg injection flow path is preferred, with cold leg injection available as an alternate.
The abnormal procedure for loss of Residual Heat Removal capability will direct use of these pumps when necessary to maintain core cooling if the RHR system is rendered inoperable.
SURRY Operations checklists for designating boric acid flow paths to the core were revised prior to the current Unit 2 refueling outage.
The revision requires one low head safety injection pump available prior to RCS dra i ndown into a reduced inventory condition.
The fl ow path and pump status will be verified by the shift turnover checklist.
The flow path checklist specifies that hot leg injection flow path is preferred, with cold leg injection available as an alternate. The abnormal procedure for loss of RHR will direct use of these pumps when necessary to maintain core coo 1 i ng if the RHR system is rendered i noperab 1 e.
The fl ow path checklists will be revised to meet the requirement for providing a second means of adding inventory and will require the availability of one (I)
Charging/HHS! pump through an available flowpath.
e
- 7.
Nozzle Dams Implement procedures and administrative controls that reasonably assure that all hot legs 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
Surry and North Anna provide RCS loop isolation by use of Reactor Coolant Isolation Valves and do not utilize Steam Generator nozzle dams.
- 8.
Loop Stop Valves Implement procedures and administrative controls that reasonably assure that all hot legs are not blocked simultaneously by closed loop stop valves unless a vent path is provided that is large enough to prevent pressurization of the RV upper plenum or unless the RCS configuration prevents RV water loss if RV pressurization should occur.
Closing cold legs by nozzle dams does not meet this condition.
Response
If maintenance requires an opening on the cold leg, procedures are being revised to require that a hot leg vent path is provided first. Also the procedures require that the cold leg isolation valve will be closed first when a loop is being isolated and the hot leg isolation valve will be opened first when returning it to service.
Standing Order #7 was issued on September 6, 1988 at Surry, specifically prohibiting placing the RCS in this adverse configuration.
Adverse configuration is defined as:
all reactor coolant loops isolated in conjunction with the opening of any RCS boundaries directly connected to the reactor vessel cold legs.
The order requires that whenever any RCS boundary connected to the cold legs is opened for maintenance, at least one loop shall remain unisolated with the respective loop bypass valve opened.
The applicable operating procedures controlling draindown and refueling operations will be modified to incorporate the provisions of the Standing Order.