ML18054A477
| ML18054A477 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 01/03/1989 |
| From: | Berry K CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| GL-88-17, NUDOCS 8901120372 | |
| Download: ML18054A477 (15) | |
Text
consumers Power l'OWERIN&
MICHlliAN'S l'ROliRESS General Offices:
1945 West Parnall Road, Jackson, Ml 49201 * (517) 788-1636 January 3, 1989 Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 DOCKET 50-255 - LICENSE DPR PALISADES PLANT -
Kenneth W Berry Director Nuclear licensing RESPONSE TO GENERIC LETTER 88-17, LOSS OF DECAY HEAT REMOVAL (60 DAY RESPONSE)
Nuclear Regulatory Commission letter dated October 17, 1988 (Generic Letter 88-17, Loss of Decay Heat Removal) discussed loss of decay heat removal events during non power operation and provided recommended expeditious actions and longer term programmed enhancements.
The letter requires submittal of a description of the actions taken to implement the recommended expeditious actions within 60 days of receipt of the letter and a submittal of a descrip-tion of enhancements, specific plans and a schedule for implementation of each of the six recommended programmed enhancements within 90 days of receipt of the letter. Attached is Consumers Power Company's response to the recommended expeditious actions for Palisades Plant.
We have actively participated in CE Owners Group reviews and have considered their corrective action recommendations.
Our response to the recommended programmed enhancements will be submitted by February 2, 1989.
Kenneth W Berry Director, Nuclear Licensing CC Administrator, Region III, NRC NRC Resident Inspector - Palisades Plant Attachment 8901120372 890103 PDR ADOCK 05000255 P
PNU OC1288-0243-NL02
CONSUMERS POWER COMPANY Palisades Plant Docket 50-255 License DPR-20 Response to Generic Letter No 88-17 dated October 17, 1988 At the request of the Commission and pursuant to the Atomic Energy Act of 1954 and the Energy Reorganization Act of 1974, as amended, and the Commission's Rules and Regulations thereunder, Consumers Power Company submits our response to NRC letter dated October 17, 1988, entitled, "Loss of Decay Heat Removal (Generic Letter No. 88-17).
Consumers Power Company's response is dated January 3, 1989.
CONSUMERS POWER COMPANY P Hoffman, Vice e
Nuclear Operations Sworn and subscribed to before me this 3rd day of January, 1989.
~
,) *i /jtu1y~
Elaine E Buehrer, Notary Public Jackson County, Michigan My commission expires October 31, 1989 OC1288-0243-NL02
Commitments Made
- 1)
Submit response to recommended programmed enhancements by February 2, 1989.
(DGMalone)
- 2)
Include final determination on second RCS level instrument usage in submittal for recommended programmed enhancement (1) (February 2, 1989)
(DGMalone).
Resident Commitments
- 1)
Train operators annually on reduced inventory operation - Resident Commitment (DWRodgers)
- 2)
Verify all operators have been trained in reduced inventory operation prior to their assumption of shift duties at the onset of reduced inventory operation - Resident Commitment (RAFenech)
- 3)
Maintain procedural requirements which include containment closure time curves - Resident Commitment (RAFenech)
- 4)
Train operators in closure of the equipment hatch - Resident Commitment (DWRogers)
- 5)
Maintain procedural requirements which ensure sufficient trained personnel are available at all times to close equipment hatch - Resident Commitment (RAFenech)
- 6)
Maintain two core exit thermocouples available for temperature monitoring during reduced inventory operation with the head installed -
Resident Commitment (RAFenech)
- 7)
Maintain procedural requirements which direct when narrow range RCS water level is to be selected and which requires level to be logged hourly - Resident Commitment (RAFenech)
- 8)
Maintain procedural requirements for operations schedulers and on-shift supervisory personnel regarding authorization of activities which could cause system upset when in reduced inventory operation - Resident Commitment (RAFenech)
- 9)
Maintain procedural requirement to have operable or readily available (within 30 minutes) two flow paths, one of which includes a high pressure safety injection pump, for addition of borated water into an intact cold leg or hot leg during reduced inventory operation - Resident Commitment (RAFenech)
- 10)
Maintain procedural requirement to keep SIRW tank greater than 50% level (125,000 gallons) for reduced inventory operation - Resident Commitment (RAFenech)
- 11)
Maintain procedural requirement to keep pressurizer manway open whenever both hot legs are simultaneously blocked by the nozzle dams - Resident Commitment (RAFenech)
IC1288-0243-NL02
- 12)
Maintain procedural requirement to install cold leg dams prior to hot leg dams and remove hot leg dams prior to cold leg dams - Resident Commitment (RAFenech)
IC1288-0243-NL02 2
i
OC1288-0243-NL02 ATTACHMENT Consumers Power Company Palisades Plant Docket 50-255 RESPONSE TO GENERIC LETTER 88-17 RECOMMENDED EXPEDITIOUS ACTIONS January 3, 1989 10 Pages
RESPONSE TO GENERIC LETTER 88-17 RECOMMENDED EXPEDITIOUS ACTIONS Recommended Expeditious Action (1)
Discuss the Diablo 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 and related loss of shutdown cooling events were previously incorporated into the continuing operator training program for operators at the Palisades Plant.
Subsequent to the issuance of Generic,
Letter 88-17, a review of the informational content of our lesson plans which incorporate this topic was completed.
As a result of this review, we have determined that our lesson plans will require only minor enhancement in order to sufficiently address the recently developed insight and corresponding implications from these scenarios as they relate to the Palisades Plant.
While this training will be provided through continuing operator training, we have also found it desirable to extract the appropriate material regarding this topic from our broader scoped lesson plans in order to provide the information in a more condensed format.
We have already utilized this condensed format to provide training to our operators prior to entering a reduced inventory condition in December 1988.
Subsequently, our training curriculum committee utilizing an INPO accredited process for determining the frequency of operator training, has determined that this training needs to be provided on an annual frequency to maintain operator prpf iciency with the material.
Therefore, we will insure that all operators have been trained in accordance with this frequency prior to their assumption of shift duties at the onset of reduced inventory operation.
For periods of reduced inventory operation which occur toward the latter half of the annual training frequency, we intend to provide the condensed foI\\Ilat for operator self study, as a means of supplementing the formal annual training.
Consumers Power Company recognizes that reduced inventory operation requires a special cognizance on behalf of plant operators.
Accordingly, we believe the above measures provide assurance that we will be prepared to deal with any operating condition which may occur during reduced inventory situations.
OC1288-0243-NL02
2 Recommended Expeditious Action (2)
Implement procedures and administration controls that reasonably assure that c.ontainment 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 RCS inventory. Containment closure procedures should include consideration of potential steam and radio-active 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 for NSSSs supplied by Combustion Engineering or Westinghouse, and (b) prior to entering an RCS condition wherein the water level is lower than
'four inches below the top of the flow area of the hot legs at the junction of the hot legs to the RV for NSSSs supplied by Babcock and Wilcox, and should apply whenever operating in those conditions.
If such procedures and administrative controls are not operational, then either do not enter the appiicable condition or maintain a closed containment.
Response
To address the containment closure issue, we have performed an analysis of the time available before Primary Coolant System (PCS) boiling will occur.
Varying values for initial PCS temperatures, PCS level and time after shutdown have all been factored into a family of curves which provide an estimate of the time between loss of shutdown cooling and core boiling.
For this analysis, no credit was taken for addition of borated water to the PCS, or for initiation of alternate cooling methods.
We will be updating our procedures with this information for use in determining the appropriate containment closure time, following loss of shutdown cooling, which will assure that the containment is closed prior to the PCS attaining a temperature of 200°F.
To facilitate closure of the containment building within the specified time frame, we employ strict administrative controls regarding temporary service lines passing.through containment penetrations (including the equipment hatch), and otherwise degraded containment penetrations.
Our procedures insure that the condition of each containment penetration may be readily ascertained for use in establishing a closed containment condition.
We require Senior Reactor Operator approval, and designation of isolation and termination methods at, or very near the penetration itself, for each OC1288-0243-NL02
temporary service line which penetrates a containment opening.
We also perform shif tly checks of the temporary service lines to both verify that no unauthorized lines are present, as well as to familiarize our operations personnel with the termination and isolation points.
A final benefit to listing the containment penetration abnormalities is that we are afforded the opportunity to restrict subsequent requests for additional service lines or other penetration degradation, as necessary, such that they may be managed in the requisite time frame for containment closure.
3 Our operators have not previously been trained in the closure of our equipment hatch.
In the future our operators will be trained in this task so that they, in addition to our mechanical maintenance personnel, may be relied upon for timely equipment hatch closure.
Presently, we have employed procedural controls which will ensure that sufficient trained personnel are available to complete this task at all times while operating at reduced inventory conditions.
With the above described measures, we are confident that we will be able to complete closure of the containment building prior to the PCS reaching 200°F.
Accordingly, we will not find it necessary to address containment closure activities under the adverse environmental conditions of steam and radioactive material release.
OC1288-0243-NL02
4 Recommended Expeditious Action (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 Reactor Vessel.
Temperature indications 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 of the Containment Building with provision 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 minutes during normal conditions.
Response
Whenever the Primary Coolant System (PCS) is being operated in a reduced inventory condition and the Reactor Vessel Head is installed, temperature indication is provided via core exit thermocouples (CETs) which have readout capability in the Control Room.
The CETs are located atop the nuclear incore instrument strings which are installed in the reactor core at selected radial locations.
The CETs, themselves, are physically located immediately above the top of the fuel elements, and, therefore, provide an accurate measure of bulk reactor water t~mperature.
Readout of the CETs is provided by the plant information processor (PIP) by simply selecting the desired CET and reading the displayed value.
The PIP however, does not have simultaneous continual display capability.
In addition, the CET readouts may also be obtained from the ptant critical function_ monitor-ing system (CFMS) which is also available in the Control Room.
On the CFMS, the desired CETs may be continually graphically trended and simultaneously displayed.
Prior to GL 88-17, our procedures specified that one CET be provided for temperature monitoring.
Subsequently, our procedures have been revised to require that two CETs be available for temperature monitoring.
Furthermore, Control Room operators are procedurally required to log the temperature readouts from two specified CETs on an hourly basis.
We believe that with the availability of two CETs as described above, we will remain adequately apprised of Reactor Vessel water temperature under all conditions where the thermocouples remain covered with water.
OC1288-0243-NL02
5 Recommended Expeditious Action (4)
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 provision for providing immediate water level values 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
For the short term, the Palisades Plant has one PCS water level indication which fully complies with GL 88-17 recommendations.
This level indication is derived from a differential pressure type level transmitter which taps off_the Loop 1 Hot Leg, with the reference side vented back to the pressurizer.
Wide range level indication is available from approximately four feet above the reactor vessel flange down to approximately 6.5 inches above the bottom of the hot leg.
Narrow range indication may be obtained by use of a selector switch which is provided in the Control Room.
In the narrow range position, the signal passes through an amplifier in order to produce full scale indication which corresponds to the lower 33% of the wide range indication.
Consequently, narrow range indication is available from slightly above the top of the hot leg down to approximately 6.5 inches above the bottom of the hot leg.
The available range includes the critical area where shutdown cooling pump vortexing would be experienced.
The level transmitter's signal is displayed by an indicator in the Control Room, and is also alarmed in the Control Room when a low level condition is sensed.
Procedure steps direct when the narrow range indication is to be selected with its corresponding alarm setpoint.
Our procedure also requires that the level reading be logged on an hourly basis.
Other available means of determining water level include a permanently installed level glass which covers approximately the same elevation as the above described indication.
The level glass is a commercial gauge glass not subject to collapsing under a vacuum and also taps off the Loop 1 Hot Leg at a tap which is independent from that described above.
The level glass is hard piped from the hot leg tap and has an attached tygon tube, vented to the containment building atmosphere, for higher elevation leyel indication during refueling water level conditions.
OC1288-0243-NL02
6 An additional supplementary means of level indication is provided by a heated junction thermocouple system.
While this indication is somewhat useful in determining step changes in level, particularly in the area below the bottom of the hot leg to the top of the fuel, the thermocouples are not strategically located near the center of the hot leg where they could be of any use in establishing PCS water level in the critical area where shutdown cooling pump vortexing could occur, but would be very useful in determining inventory remaining before core recovery.
Currently we ut.ilize all of the above methods as cross checks in determining actual PCS level.
At this time, we have not determined what means we will employ as our secqnd level indication which will fully comply with the GL 88-17 recommendation.
We plan' to further review our options and make a final determination with respect to this topic under Progra~ed Enhancement (1), which addresses instrument availability during reduced level conditions.
\\
OC1288-0243-NL02
7 Recommended Expeditious Action (5)
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 the RCS will remain in a stable and controlled condition.
Such additional measures include both prevention of a loss of DHR and enhanced monitoring requirements to ensure timely response to a loss of DHR should such a loss occur.
Response
Several years ago, the Palisades Plant Operations Department was reorganized, creating an off-shift scheduling group which functions to coordinate the scheduling of activities between the Operations, Engineering and Maintenance Departments.
~outine responsibilities of this group include the administration, prioritization and daily scheduling of operational shift activities, and providing Operations Department input to Plant Work (activity) schedules.
In essence, this group maintains a significant degree of r~sponsibility for ensuring that scheduled.work activities will be in harmony with the specific operational condition of the plant.
The Operations Scheduling Supervisor, who heads this work group, is required by our administrative procedures to hold a Senior Reactor Operators license.
We believe that through the normal course of their duties, the Operations
- Scheduling Group provides an excellent control point for ensuring that pro-posed activities which could.result in undesirable effects upon either the Primary Coolant System or our ability to maintain stable shutdown cooling system operation, when at a reduced inventory condition, are avoided.
Accordingly, we have included in our procedural requirements for reduced inventory conditions, a precautionary statement for both operations schedulers and on-shift supervisory personnel regarding the authorization of activities which could cause a system upset.
Since virtually every activity undertaken is done under this level of Operations Department cognizance, we believe that deliberate evolutions which would lead to such perturbations are effectively precluded.
Additionally, in the event that an activity which could potentially result in a system perturbation must be performed during reduced inventory conditions, we believe that the level of cognizance associated with this decision will also ensure that a heightened awareness and appropriate compensatory measures are established for both prevention and detection of adverse system conditions.
OC1288-0243-NL02
Recommended Expeditious Action (6)
Provide at least two available or operable means of adding inventory to the RCS th.at are in addition to pumps that are a part of the normal 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 assure the flow does not bypass the Reactor Vessel before exiting any opening in the RCS.
Response
When at reduced inventory conditions, we are assured of our ability to add inventory to the Primary Coolant System (PCS) through a procedural-change 8
which we have implemented.
Our procedure now requires that two flow paths remain operable or readily available (within 30 minutes) for addition of borated water to the PCS.
In accordance with GL 88-17, at least one of the specified flow paths will include a high pressure safety injection pump.
The remaining path will utilize either a charging pump, containment spray pump or the second high pressure safety irijection pump.
In this manner, potential pressure buildup following a loss of shutdown cooling event will not reasonably interfere with our ability to refill the PCS.
We have also specified that our safety injection and refueling water tank (SIRWT) be maintained at greater than 50% level (125,000 gallons) to provide an adequate suction supply for the above specified pumps.
We specify the inventory addition pathway such that the flow rate available from each of the respective inventory addition paths is sufficient to keep the core covered, based upon our analysis of water boil-off rates.
We are also sensitive to the fact that certain conditions could exist, depending upon the injection pathway, which could preclude sufficient water from actually entering the reactor vessel before exiting out a postulated opening in the PCS.
Therefore, our procedure will be revised with precautionary information to ensure that the flow path is injecting into either an intact cold leg loop or through a hot leg injection pathway.
OC1288-0243-NL02
Recommended Expeditious Action (7)
(Applicable to Westinghouse and Combustion Engineering nuclear steam supply system (NSSS] designs)
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 pressuri-zation of the upper plenum of the RV.
Response
9 An analysis has been performed which confirms that the pressurizer manway is a sufficiently sized vent path to prevent unacceptable pressurization of the reactor vessel's upper plenum area.
Our procedures will be revised prior to entry into reduced inventory operation with both hot legs blocked to ensure that this vent path is established and remains in effect whenever both hot legs are simultaneously blocked by the nozzle dams.
Additional restrictions on time after shutdown and high pressure
_safety injection pump (HPSI) availability which are necessary to support the use of the pressurizer manway as an acceptable vent path will also be proceduralized.
Our procedures on nozzle dam installation have previously been revised to address the correct sequencing of dam installation.
Accordingly, we are assured that the cold leg dams will be installed first, prior to hot leg dam installation.
Upon removal, the hot leg dam will be removed first, followed by the cold leg dams.
OC1288-0243-NL02
~
10 Recommended Expeditious Action (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 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
This expeditious action is not applicable to the Palisades Plant.
OC1288-0243-NL02