ML18052B323

Forwards Response to Request for Info Re Generic Ltr 87-12, Loss of RHR While RCS Partially Filled. Two Plant Mods Being Planned for 1988 Refueling Outage,Including Addition of Reactor Water Low Level Alarm,When in Shutdown Condition

ML18052B323
Person / Time
Site:	Palisades
Issue date:	09/18/1987
From:	Berry K CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
GL-87-12, NUDOCS 8709220503
Download: ML18052B323 (19)

Text

consumers Power Kenneth W Berry PllWERINli Director lllllClllliAN'S PROGRESS Nuclear licensing Genera.I Offices: 1945 West Parnall Road, Jackson, Ml 49201 * (517) 788-1636 September 18, 1"987 Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 DOCKET 50-255 - LICENSE DPR PALISADES PLANT -

RESPONSE TO 10CFRS0.54(f) INFORMATION REQUEST -

LOSS OF-RESIDUAL HEAT REMOVAL WHILE REACTOR COOLANT SYSTEM IS PARTIALLY FILLED - GENERIC LETTER 87-12 Enclosed are t.he responses to the information requested in Generic Letter 87-12. The Palisades procedures and practices with respect to shutdown cooling and mid-loop operations have been reviewed both with respect to the Generic Letter and previous INPO and NRC documents (SOER 85-04, SER 15-87, and IEN 87-023). Several procedural changes have been recommended as enhancements and will be in place prior to draining the Primary Coolant System during the upcoming October Maintenance Outage. We have found that the current practices at Palisades are sufficient to prevent a loss of shutdown cooling event of the type experienced at Diablo Canyon.

Two plant modifications are also being planned for the 1988 refueling outage.

The first is to add a reactor water low level alarm, when in shutdown condition, in the control room. The second modification would provide an alternative method to operate three control valves in the shutdown cooling system.

Kenneth W Berry Director, Nuclear Licensing CC Administrator, Region III, NRC NRC Resident Inspector - Palisades Attachment a709220 5 0C?,

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• OC0987-0156-NL02

-~I CONSUMERS POWER COMPANY Palisades Plant Docket 50-54 License DPR-20 Response to Generic Letter No 87-12 dated July 9, 1987 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 July 9, 1987, entitled,"Loss of Residual Heat Removal While Reactor Coolant System is Partially Filled." Consumers Power Company's response is dated September 18, 1987.

CONSUMERS POWER COMPANY By ---~~~~~~~::::---:--::--

F W Buckman, Nuclear Operations Sworn and subscribed to before me this 18th day of September 1987.

~i~M£~

Elaine E Buehrer, Notary Public Jackson County, Michigan My commission expires Octobe~ 31, 1989 OC0987-0156-NL02

v ATTACHMENT Consumers Power Company Palisades Plant Docket 50-255 LOSS OF RESIDUAL HEAT REMOVAL WHILE REACTOR COOLANT SYSTEM IS PARTIALLY FILLED September 18, 1987 16 Pages IC0887-0001C-NL02

1 LOSS OF RESIDUAL HEAT REMOVAL WHILE REACTOR COOLANT SYSTEM IS PARTIALLY FILLED

1. NRC CONCERN:

A detailed description of the circumstances and conditions under which your pl~nt would be entered into and brought through a draindown process and operated with the RCS partially filled, including any interlocks that could cause a disturbance to the system. Examples of the type of information required are the time between full-power operation and reaching a partially filled condition (used to determine decay heat loads); requirements for minimum steam generator (SG) levels; changes in the status of equipment for maintenance and testing and coordination of such operations while the RCS is partially filled; restrictions regarding testing, operations, and maintenance that could perturb the nuclear steam supply system (NSSS); ability of the RCS to withstand pressurization if the reactor vessel head and steam generator manway are in place; requirements pertaining to isolation of containment; the time required to replace the equipment hatch should replacement be necessary; and requirements pertinent to reestablishing the integrity of the RCS pressure boundary.

RESPONSE

The Palisades Shutdown Cooling System (SDCS) is composed of redundant components (2 pumps, 2 heat exchangers, 4 return lines) and common piping (common suction line, common heat exchanger inlet *and outlet lines). Like all plants, Palisades is also susceptible to a loss of SDC due to pump cavitation induced by air entrainment during periods of low reactor water level operation (mid-loop operations).

• The Primary Coolant System (PCS) can be drained. from each of the cold legs

• ,and from the loop 1 hot leg. The . SDC suction line is attached to the loop 2 .hot leg. The centerline of the hot leg is at elevation 618' 2.5". It is important to note that due to-the construction of ~he Primary Coolant Pumps, the PCS cannot be drained below 617' 8 11 (-6.5" from hot leg centerline) using the cold leg drains. It is also important to note that, LPSI pump cavitation due to vortexing has not been experienced at.this level. rast operation indicates pump cavitation starts below 617' 6" or

-8.5" from the centerline. A step in the procedure controls PCS draindown to prevent draining from the hot leg drain unless the action is approved by the Operations Superintendent *. Loss of shutdown cooling due.to overdraining is t~erefore unlikely.

The PCS can be placed and operated in a partially-filled condition for several reasons; these include:

S/G Nozzle Dam Installation (for S/G Eddy Current Testing).

Maintenance on or inspection of PCS components.

Modifications to PCS components.

During these evolutions, the PCS will normally be tagged out for workmens' protection. This would result in only the following pumps being available (ie, not tagged as part of PCS tagout):

2 LPSI Puinps 1 Charging pump IC0887-0001C-NL02

2 In addition, the suction valves from the SIRWT to the LPSI, HPSI, and Containment Spray Pumps are tagged closed as part of the PCS tagout. In the event of an emergency, any of these tags could be cleared. An initial condition for draining the PCS is that it be at atmospheric pressure, ie, vented. Per Technical Specification 3.1.8, the PCS can be protected from overpressurization in two ways:

1) Via the LTOP system which uses the PORVs (actual setpoint = 375 psia)

2) Establishing a vent path ~1.3 in 2 Therefore, it is possible to vent the PCS to atmospheric pressure while still taking credit for the LTOP system as the primary overpressure protection mechanism.

Interlocks which could cause a disturbance of the Shutdown Cooling System include the pressure interlock to the Shutdown Cooling Suction Valves (M0-3015 and 3016). This interlock allows opening of these valves when PCS pressure is sufficiently low (ie, <275 psia) to avoid overpressurizing the Shutdo~ Cooling System. This interlock does not automatically close these valves if pressure increases above the setpoint; it simply serves as a permissive to initially op~n these valves.

The standby feature in the LPSI pumps is also an interlock which could cause a system disturbance. This feature automatically starts the LPSI pump which is placed in. "STANDBY" when LPSI discharge pressure is sufficiently reduced (setpoint = 75 psig). This feature is not normally used at Palisades. Palisades Procedure SOP 3, "Safety Injection and Shutdown Cooling System", contains the following instruction "With PCS drained below centerline of hotleg the LP pump not in service shall not be placed in standby." This precaution will prevent automatic starting of the second LPSI pump when the operating pump trips. The intent is to reduce the probability of simultaneous common failures (ie, due to cavitation) of both LPSI pumps.

Palisades procedures do not require a minimum time to elapse between full power operation and establishing mid loop operation. Specific requirements to determine the PCS heatup rate are provided if PCS level is drained below the centerline of the hotleg, or shutdown cooling needs to be secured for maintenance. At a minimum,* it is estimated that approximately 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> would elapse between full power operation and establishing partial fill condition. There are no specific procedural requirements for steam generator level during partial fill evolu~ions~ but*

the standard practice is to always maintain the tubes covered to prevent any erosion/corrosion of the tubes by direct oxygen contact with a wetted tube on the secondary side. The only acceptable reason for draining the

• S/G below ~he top ef the tube bundle is to perform tube removals, tube support repairs or installing instrument connections.

Changing of equipment status/coordination and testing for maintenance while the PCS is partially filled is controlled by the Operations Scheduling Group. Since the Technical Specification and procedural restrictions are fairly broad, this group uses Technical Specification and

• procedure requirements in conjunction with good engineering experience in coordinating these activities.

IC0887-0001C-NL02

3 Isolation of containment is not required prior to entering partial-fill operations; however, the Off Normal procedure for Loss of Shutdown Cooling does contain containment integrity guidance (see response 4).

Closure of the equipment hatch is estimated to require less than one hour.

This may require removal of cables/hoses and the walkway grating (secured by 2 bolts). Closure in the event of boiling in the core, however, is not particularly important to prevent a significant offsite release. *At Palisades, the equipment hatch opens into the Spent Fuel Pool area. This area is served by ventilation fans which exhaust the area through charcoal filters. These filters are currently required by Technical Specifications to be in service when fuel is being moved in the Spent Fuel Pool or ~n the reactor. They could, however, be immediately placed in service in the event core boiling or another event made containment integrity desirable.

With these fans operating, air flow enters containment through various openings (ie, the personnel airlock) and out through.the equipment hatch into the Spent Fuel Pool area~ Consumer Power Company intends to maintain the availability of the spent fuel pool ventilation exhaust system .when the PCS is drained and the hatch equipment is open. Additionally, Off-Normal Procedure, ONP-17, will be revised to instruct operators to shift t~e SFP exhaust through the charcoal filters if SDC is lost and the equipment hatch is open.

• IC0887-0001C-NL02

4

2. NRC CONCERN:

A detailed description of the instrumentation and alarms provided to the operators for controlling thermal and hydraulic aspects of the NSSS during operation with the RCS partially filled. You should describe temporary connections, *piping, and instrumentation used for this RCS condition and the quality control process to ensure proper functioning of such connections, piping, and instrumentation, including assurance that they do not contribute to loss of RCS inventory or otherwise lead to perturbation of the NSSS while the RCS is partially filled. You should also provide a description of your ability to monitor RCS pressure, temperature, and level after the RHR function may be lost.

RESPONSE

Listed on Table 1 are the instrumentation and alarms for controlling thermal and hydraulic aspects of the NSSS during partial fill operations.

All instrumentation is permanently installed; a "yes" in the Q-listed column indicates that equipment is subject to the Quality Assurance

.Program.

PCS inventory is monitored by a daily Technical Specification surveillance to check the PCS for leakage. This surveillance is accomplished when the plant is in a partial fill condition by visually checking the PCS (ie, containment walkdown). In addition, FSAR Section 4.7.1 states that the Containment Sump level alarm is set *at 3" which would equal 1,500 gallons of water. This is an additional indication to operators to show a loss of inventory.

The ability to monitor PCS pressure, temperature, and level following a loss of the RHR function is dependent upon the initial plant conditions and the cause of the loss of RHR_. As a minimum, it can be seen that at least one level, pressure, and temperature instrument should remain available since there are redundant indications available. There are no Technical Specifications or procedural restrictions regarding the availability/operability for any of this equipment during partial fill operations .*

Palisades level instrumentation consists of a level indicator and a sight glass. The level indicator, LI-0105, is located in the Control Room on Panel Cl2 and is fed by LT-0105. The transmitter has connections to the pressurizer and the bottom of the loop 1 hot leg. LI-0105 begins to read less than 100% level when the reactor water level drops below the 628' 5 11 elevation *. Thus, LI-0105 is designed to and will provide remote indication of reactor water level during mid-loop operations. Because of the connec"tion to the pressurizer, LI-0105 will not be affected by a vacuum in the pressurizer (caused by draining too f~st in conjunction with a small pressurizer vent) unless a* separate gas bubble also exists in the reactor head. In the region of interest, when level is below the top of the hot-leg piping pressure in the PCS will not affect instrumen.t

• accuracy.

IC0887-0001C-NL02

5 A backup level indicator LG-0105 is a sight glass that taps off the bottom of the loop 1 hot leg and is vented to containment atmosphere. The lower part of the sight glass *(below elevation 628'5") which spans the reactor vessel level is composed of glass; the upper part is a Tygon tube. The Tygon tube is filled when refueling cavity water level is above the reactor vessel. LG-0105 provides a reliable method for local monitoring of the reactor water level during mid-loop operations. During draining of the PCS, the level gage may indicate conservatively lower than actual level if a vacuum occurs in the pressurizer.

Installation of a low water level alarm, derived from LI-0105, is currently being investigated for Palisades. The alarm will to be installed in the 1988 refueling outage.

A low shutdown cooling flow alarm does exist at the plant. The alarm appears on the Critical Functions Monitor System. There are SDC flow indicators available in the control room, but they are not included on the regular shift logsheets. Since there are no audible alarms, a loss of SDC flow condition might not be noticed immediately.

There are other indications that would alert the op~rators to loss of SDC flow. These would include rising PCS temperature (checked hourly), pump trip alarms, and valve position indicator lights. These indications are judged to be acceptable substitutes for the low flow alarm.

At Palisades, the reactor water level indicator in the control room, LI-0105, is typically monitored at least once per shift. For the upcoming Maintenance outage, we intend to perform at least hourly checks of LI-0105 and other shutdown cooling instrumentation while the PCS is drained to mid-loop. The level gauge in the containment, LG-0105, is checked once per day while on shutdown cooling.

Specific requirements on reactor water level are laid.out in Standard Operating Procedures SOP 1 and SOP 3. Essentially, the procedures provide for enhanced awareness of the importance of maintaining PCS level above 617'6" (8.5" below centerline). Operations Superintendent review/approval is required, per SOP 3, prior to draining below 617'6".

IC0887-0001C-NL02

y 6

TABLE l READOUT ITEM DESCRIPTION LOCAIION Q-LISIED

1) FIC-0306 Shutdown Cooling Flow (0-8000 GPM) Control Room - C02 Panel Yes

2) TR-0351 Shutdown Cooling Iemps - Io and Control Room - C02 Panel Yes from PCS (0-400 °F)

3) Motor Operated a) M0-3015 & 3016 (Shµtdown Cooling Control Room - C02 Panel Yes Valve Controls Isolation Valves) b) M0-3008, 3010, 3012*, 3014 (LPSI Control Room - C03 Panel Yes injection Valves) c) M0-3190, 3199 (LPSI Pump Suction Control Room - C03 Panel Yes Valves from SDC)

4) Air Operated CV-3055 (Shutdown Cooling Hx Control Room - C02 Panel Yes Valve Control Inlet Isol) *

5) a) HIC-3025A a/b) Shutdown Cooling Hx Outlet a) Control Room - C02 Panel No b) HIC-3025B -Valve Control b) C-33 Panel Yes 6)° P-67 A and B -LPSI Pump Breaker Open/Closed Control Room - C03 Panel Yes Indication Indication

7) a) LI-0105 Rx Vessel Level Control Room - Cl2 Panel No (Note 1) b) LG-0105 Rx Vessel Level Locally in Containment No (Note °!)

8) PTR-0115 Loop 1 Cold Leg Iemp (0-600 °F) Control Room - Cl2 Panel Yes and PZR Pressure (0-3000 psig)

9) PTR.-0125 Loop 2 Cold Leg Iemp (0-600 °F) Control Room - Cl2 Panel No (Note 1) and PZR Pressure (0-600 psig)

10) Alarms

• a) EK-1155 a) West ESS Room Pumps CCW Low Flow Control Room Alarm Panels See Note 2 b) EK-1156 b) East ESS Room.Pumps CCW Low Flow Control Room Alarm Panels See Note 2 c) EK-1157 c) LPSI Pump Tripped Control Room Alarm Panels No d) EK-1158 d) LPSI Standby Pump Running Control Room Alarm Panels No e) EK-1306 e) LPSI HOV Overload Control Room Alarm PanelS No f) EK-0712 f) Shutdown Cooling HOV Overload Control Room Alarm Panels No

11) Core Exit Core Exit Thermocouples (CETS) Control Room Yes/No Thermocouples (See Note 3)

Notes: 1) Primary isolation valves for applicable transmitters/indicators "are Q-listed

2) Q listin$ has not been determined - i.e. treated as Q-listed

3) 16 CEIS are Q-listed (there are 45 total). Ability to use CEIS is dependant upon Rx Vessel Head being installed and CEIS being in service.

IC0887-0001C-NL02

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3. NRC CONCERN Identification of all pumps that can be used to control NSSS inventory include: (a) PUJJlPS you require be operable or capable of operation (include information about such pumps that may be temporarily removed from service for testing or maintenance); (b) other pumps not included in item a (abpve); and (c) an evaluation of items a and b (above) with respect to applicable TS requirements.

RESPONSE

Item 3 (a) .- Palisades Technical Specification 3. 2 .1 contains the operability requirements for NSSS inventory control when the plant is in cold shutdown. This requires maintaining at least one flow path to the co.re for boric acid injection whenever fuel is in the reactor. Tpis would require at least one of* the following pumps operable:

Charging Pumps - (total of 3 available)

Boric.Acid Pumps - (total of 2 available - can only take credit for if RCS is vented or Rx Head is removed)

Normally, the PCS would be tagged out for maiµtenance when the plant is in cold ~hutdown. This would result in only one Charging Pump being

.operable. Other Charging Pumps which are tagged may or may not be available -for prompt restoration, ~ince they might be undergoing

~intenance. Boric Acid Pumps are not tagged as part of the PCS tagout bu~ may or may not be available since they might be undergoing maintenance.

Item 3(b) - Other pumps which could be used for ,NSSS inventory control include:

HPSI Pump~ (total of 2 available)

LPSI Pumps - (total of _2 available)

Containment Spray Pumps - (total of 3 available)

The LPSI pumps serve the primary RHR (ie, Shutdown Cooling) circulating 0

function; LPSI pump operabi+ity is not specifically'required by Palisades Technical Specifications. The availability/oper~bility of at least one pump is implicitly required, since uncontrolled loss of this primary function would result in activation of the Off Normal Procedure for Loss of Shutdown Cooling.

The Containment Spray Pumps and HPSI pumps are normally not available when the plant is in cold shutdown since these pumps.are tagged as part of the PC~ tagout.

Inventory control can also be available via gravity feed from the SIRW tank.

Item 3(c) - As.stated above, Palisades Technical Specification requirements for NSSS inventory control can be maintained in several ways. Specific requirements for operability do not exist in Palisades Technical Specifications, so the degree of redundancy to support NSSS inventory control can be zero.

IC0887-0001C-NL02

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4. NRC CONCERN A description of the containment closure condition you require for the conduct of operations while the RCS is partially filled. Examples of areas of consideration are the equipment hatch, personnel hatches, containment purge valves, SG secondary-side condition upstream of the isolation valves (including the valves), piping penetrations, and electrical penetrations.

RESPONSE

Containment Integrity requirements are detailed in Palisades Technical Specification 3.6.1 and 3.8.1. When the plant is in cold shutdown, the only Technical Specification that would be appl*icable is T. S. 3. 8 .1.

Since this specification deals with Refueling Operations, it would not apply for conditions when the PCS is partially filled. Therefore, there are no Technical Specifications which govern containment closure during operations with the PCS partially filled.

Palisades' procedures do not include any special provisions for

• containment closure during PCS partial fill activities. If a loss of Shutdown Cooling were to occur, the Off Normal P~ocedure for Loss of Shutdown Cooling instructs operators to establish containment integrity prior to the PCS exceeding 210°F. (per T.S. 3.6.1). Establishing containment integrity under these conditions may require actions which

• include closing the equipment hatch, personnel hatches, and containment purge valves, etc.

As discussed in the response to item 1. above, the Spent Fuel Pool area ventilation exhaust fans can maintain positive control over potential releases without establishing containment integrity. These fans can maintain airflow into various containment openings and out of the equipment hatch. The HEPA and charcoal filters in the ventilation exhaust line should provide adequate control over the release of airborne activity~

IC0887-0001C-NL02

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5. NRC CONCERN Reference to and a summary description of procedures in the control room of your plant which describe operation while the RCS is partially filled*.

Your response should include the analytic basis you used for procedures

• development. We are particularly interested in your treatment of draindown to the condition where the RCS is partially filled, treatment of minor variations from expected behavior such as caused by air entrainment and de-entrainment, treatment of boiling in the core with and without RCS pressure boundary integrity, calculations of approximate time from loss of RHR to core damage, level differences in the RCS and the effect upon instrumentation indications, treatment of air in the RCS/RHR system, including the impact of air upon NSSS and instrumentation resp'onse, and treatment of vortexing at the connection of the R,HR suction line(s) to the RCS.

Explain how your analytic basis supports the following as pertaining to your facility: (a) procedural guidance pertinent to timing of operations, required instrumentation, cautions, and critical pa*rameters; (b) op.erations control and communications requirements regarding operations*

that may perturb the NSSS, including restrictions upon testing, maintenance, and coordination of. operations that could upset the condition of the NSSS; and (c) response to loss of RHR, including regaining control of RCS heat removal, operations involving the NSSS if RHR cannot be restored, control of effluent from the containment if containment was not in an isolated condition at the time of loss of RHR, and operations to

• provide containment isolation if containment was not isolated at the time of loss of RHR (guidance pertinent to timing of operations, cautions and warnings, critical parameters, and notifications is to be clearly described) * *

RESPONSE

(a) Palisades procedures which describe operation while the PCS is partially filled are SOP 1 and SOP 3. SOP 1 contains procedural steps for draining the PCS, while SOP 3 contains procedural steps for control of the Shutdown Cooling system at lower PCS levels (see response 8).

There is no formal analytic basis for these procedures development.

Specific actions (eg, "Op.en MV-1167") are based on system design and logical progression of system manipulations to achieve the desired result.

Specific cautions are based on previous.operating experience or good engineering practice.

Prior to the 1987 Maintenance Outage it is the intent of Consumers Power to complete analyses of core heatup rates and time to core uncovery under conservative initial conditions.

Currently, a precise water level/pump flow correlation does not exist to predict the onset of vortexing or cavitation. Historical information indicates that LPSI pump cavitation, begins at water levels between 8" and 9" below the centerline of the hot legs. Plant operators receive training IC0887-0001C-NL02

10 on the contents of SOP 1, SOP 3, and ONP 17.* These procedures contain guidance on minimum water levels and precautions to take when throttling shutdown cooling flow.

(b) At Palisades, only the operators perform valve manipulations for system lineups and tests. This practice leads to a greater knowledge of plant activities and more positive control from the control room operators. Additionally, all maintenance activities must be approved by the Control Room prior to performance. At other plants, personnel other than operators (e.g., engineers) can manipulate valves to perform tests. In such situations, *personnel can be conducting tests without specific awareness by the operators. Consumers Power believes that the practices used at Palisades provide adequate barriers to the performance of actions without control room authorization.

(c) Palisades Off Normal Procedure ONP 17, "Loss of Shutdown Cooling,"*

contains two alternative methods of cooling the core should shutdown cooling flow be lost. The two methods are: 1) use of a HPSI pump and, 2) use of the Spent Fuel Pool Cooling system. If shutdown cooling is lost due to a loss of cooling water to the shutdown cooling heat exchangers, ONP 17 has instructions on use of alternate cooling water supplies. Not listed in ONP 17 are other methods of providing core cooling during a loss of shutdown cooling.

Some alternate methods of core cooling not listed in ONP 17 include use of a spray pump and gravity feed from the SIRWT to the loop 1 hot leg. The actual choice of the method used depends on how SDC has failed. For example, if the trouble is in the SDC suction line (eg, M0-3015 or M0-3016), recirculation cooling with a HPSI or spray pump is not possible

- only injection via the Boric Acid flow path can be used. Because the list of possible alternatives is dependent on the SDCS failure mode, it does not seem appropriate to place such a list in ONP 17. ONP 17 would become unwieldy and.hard to read.

Another *f~ctor complicating the selection of an alternate core cooling method is the fact that when the plant is in mid-loop conditions, the PCS will be tagged out. The PCS tagout includes the HPSl pumps, the containment spray pumps, and two of the three charging pumps. Thus, given a loss of shutdown cooling, a preferred alternate method of cooling may be unavailable due to maintenance work being performed at the time. The added uncertainty of unplanned maintenance, which cannot be accurately predicted in advance, also argues against putting a list of alternative core cooling methods in ONP 17. Consumer Power believes the selection of the alternative core cooling method used during a loss of SDC should continue to be made by the Shift Supervisor, based on the condition of the plant at the time. -

IC0887-0001C-NL02

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6. NRC CONCERN A brief description of training provided to operators and other affected personnel that is specific to the issue of operation while the RCS is partially filled. We are particularly interested in such areas as maintenance personnel training regarding avoidance of perturbing the NSSS and response to loss of decay heat removal while the RCS is partially filled.

RESPONSE

Training in Shutdown Cooling issues has been provided to operators as part of ongoing training (Industry Experience and Plant Modifications) and will be provided in future operator training.

Licensed Operator Requalification Training includes discussions on Operating Procedures (eg, SOPs) and Emergency/Off-Normal Procedures.

Also, SOERs are discussed for their applicability to Palisades. These discussions would include the applicable procedure requirements for partial fill operations.

Information on shutdown cooling reliability has also been incorporated permanently into the following lesson plants:

PDED Shutdown Cooling (AO initial systems)

PNOB Shutdown Cooling (RO/SRO)

Maintenance personnel, as well as all contractors, etc., receive training which stresses adherence to procedures as part of required General Employee Training. Additionally, as part of the plant preoutage preparations meeting (prior to the October Maintenance Outage),

maintenance personnel will be reminded to keep the control room informed of their activities in the plant. All personnel will be reminded to contact the control room if they observe anything out-of-the-ordinary in the plant, including the possibility of a loss of shutdown cooling.

Again we emphasize that only operations personnel operate valves and while doing so are in communication with the control room operators.

IC0887-0001C-NL02

v 12 7* NRC CONCERN Identification of additional resources provided to the operators while the RCS is partially filled, such as assignment of additional personnel with specialized knowledge involving the phenomena and

.instrumentation.

RESPONSE

. Partial fill operations of the PCS do not require any additional personnel staffing requirements. The operations licensed shift personnel are qualified and trained in the proper procedures, ihstrumentation available, and Off Normal Procedures (see response 6).

Historical information indicates that LPSI pump cavitation begins at water levels between 8" and 9" below the centerline of the hot legs. Plant operators receive training on the contents of SOP 1, SOP 3, and ONP 17 which contain adequate guidance on minimum water leveis and on_ precautions to take when throttling shutdown cooling flow.

IC0887-0001C-NL02

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8. NRC CONCERN Comparison of the requirements implemented while the RCS is partially filled and requirements used in other Mode 5 operations. Some requirements and procedures followed while the RCS is partially filled may not appear in the other modes. An example of such differences is operation with a reduced RHR flow rate to minimize the likelihood of vortexing and air ingestion.

RESPONSE

Th~ only specific proce~ural difference which appears for partial fill operations is contained in SOP 3, Section 7.3.3.h. It specifies the following:

" I f PCS is to be drained below centerline of hotleg, shutdown cooling flow may be throttled (minimum of 750 gpm) as long as all of the following are met: a) PCS heatup rate determined, b)

Auxiliary Operator stationed at operating LPSI pump to check for cavitation, c) Auxiliary Operator stationed at **LG-0105. With PCS drained below centerline of hot leg the LP pump not in service shall not be placed in standby.

• NOTE: Do not drain PCS below 617'6" without Operations

• superintendent review/approval.

NOTE: If LPSI pump cavitation occurs, secure drai~ing, refill PCS as necessary."

The above pro.cedure steps were based upon actual plant evolutions. during the 1985 refueling outage.

Also, procedural guidance for secur~ng shutdown cooling for maintenance is contained in SOP-3, section 7 .8 which reads.:

"To* ~ECURE.SHUTDOWN COOLING FOR MAINTENANCE The followipg are general guidelines for securing shutdown cooling.

If possible, securing shutdown cooling sh9uld be done when Reactor Head is removed and cavity and fuel pool are tied together.

The securing of shutdown cooling should be scheduled as late as possible after shutdown to allow for more heat decay.

A shutdowo heat up rate shall be determined by se~uring shutdown cooling for approximately 1 to 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br />. Then restart shutdown cooling and determine what the heat up rate has been for this time period.

After heat-up rate is determined, a time restriction for out of service of the shutdown cooling shall be made. This restriction shall ensure that shutdown is returned to service before a PC system temperature of 180°F is exceeded.

I f securing shutdown cooling is required with Reactor Head in place the same guidelines as given in Steps 7.8.3 and 7.8.4.shall be used.

IC0887-0001C-NL02

y 14 If the time restriction can not be met partial, or full off loading of the core may need to be done."

Therefore, procedural requirements are in place which control partial fill operations within equipment operation limits and also establish guidelines for removing the shutdown system from operation *.

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9. NRC CONCERN As a result of your consideration of the_se issues, you may have made changes to your current program related to these issues. If such changes have strengthened your ability to operate safely during a partially filled situation, describe those changes and tell when they *were made or are scheduled to be made.

RESPONSE

Actions taken at Palisades relating to mid-loop operations have primarily been in response to three industry/NRG documents: SOER 85-04, SER 15-87, and IEN 87-023. The actions initiated from each document are de~ailed below.

In response to SOER 85-04, Palisades has made, or is making, the following changes:

1) System Operating Procedure, SOP 3, "Safety injection-and Shutdown Cooling System" was changed to include the following statement in

• 1 section 7.3.h: "With PCS drained below centerline of hotleg, the LPSI pump not in-service shall not be placed in standby." This precaution is intended to prevent the automatic starting of the second LPSI pump when the first pump trips. This will reduce the probability of simultaneous common failures (ie, due to cavitation) of both LPSI pumps. *This action was completed prior to April 1, 1986.

2) Addition of a backup*method of operating CV-3006, CV-3025, and CV-3055 is scheduled for the 1988 refueling outage. This modification is designed to provide a backup method of operati~g these critical shutdown cooling valves.

3) Installation of a low level alarm on the control room RV level indicator LI-0105 is being investigated. If feasible, this modification will provide the control room operators with an audible.

indication of low reactor water level. This alarm can be useful during mid-loop operations when the water level in the hot legs is only a few inches above the levei at which LPSI.pump vortexing can occur.

Because an alarm could not be !~stalled prior to the 1987 Maintenance outage, it is planned to have at least hourly checks of shutdown cooling flow and reactor vessel level made by the operators during mid-loop operations.

4) In response to INPO SOER 85-04, specific training has been provided to operators on prevention of and responses to a loss of shutdown cooling. The information contained in the SOER was incorporated _in the following lesson plans.

PDED Shutdown Cooling (AO's Initial Systems)

PNOB Shutdown Cooling (RO's and SRO's) .

Industry Experience and Plant Modifications IC0887-0001C-NL02

y 16 Additional operator training on shutdown cooling reliability and special controls for mid-loop operation is planned prior rto the upcoming maintenance outage. --

In response to IEN 87-023 and SER 15-87, Palisades has made the following procedural changes:

5) Changed SOP 3, "Safety Injection and Shutdown Cooling System", and ONP 17, "Loss of Shutdown Cooling", to include a provision for evacuating personnel from the steam generator heads (if the manways are open) prior to refilling the PCS. These changes were effective on August 5,_1987.

6) Changed ONP 17, "Loss -of Shutdown Cooling", to direct the operator to either ref ill the PCS or throttle SDC flow prior to starting the second LPSI pump i f the first pump _tripping is the cause of the loss of SDC.

This change was effective on August 5, 1987.

7) As discust;;ed in the response in Concern 1, normal practice is to reduc~

reactor vessel level using the cold *1eg drains only to preclude potential

_loss of shutdown cooiing by inadvertent overdraining. This practice has been formalized in SOP 1.

In addition to the above actions taken, or being taken, Palisades has increcised the reliability of the shutdown cooling system in general by _

addressing the causes of each loss* of shutdoWn cooling event that has occurred at- Palisades.-_

The main-. cause of. previous loss of shutdown cooling events at Palisaqes has been water. in the air line to CV-3025. To correct this problem, an in-line filter was in~talled for this valve. Additionally, the plant instrument air dryer has recently been replaced, additional header blowdown connections were added, _and a_J>M was instituted for periodic blowdowns to ensure water and other impurities do not accumulate in the air lines. This helps insure the existence of a dry air supply to shutdown cooling system valves as weil as all plant ~ir-operated valves.

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