ML20245J802
| ML20245J802 | |
| Person / Time | |
|---|---|
| Site: | South Texas  |
| Issue date: | 08/03/1989 |
| From: | Vaughn G HOUSTON LIGHTING & POWER CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| GL-88-17, ST-HL-AE-3097, NUDOCS 8908180191 | |
| Download: ML20245J802 (20) | |
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ERRATA Issued 08/04/89 Houston Lighting & Power correspondence ST-HL-AE-3097 was inadvertently distributed without the date of signature indicated. This document is being' redistributed in its entirety. l 1
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The Light company -
P.O. Box 1700 liouston, Texas 77001 (715) 228 9211 Ilouston lighting ae Power August 03, 1989 ST-HL-AE-3097 File No.: G3.8 10CFR50 U. S. Nuclear Regulatory Commission Attention: Document' Control Desk Washington, DC 20555 South Texas Project Electric Generating Station Units 1 & 2 Docket Nos. STN 50-498, STN 50-499 Revised Response to NRC Generic Letter 88-017: " Loss of Decay Heat Removal" Houston Lighting & Power Company (HL&P) has completed its evaluation of the subject Generic Letter received on October 20, 1988, and submits the attached revised response for Units 1 & 2 of the South Texas Project Electric Generating Station (STPEGS.) An initial response to Generic Letter 88-017 was submitted by letters dated December 9, 1988 ST-HL-AE-2877.
and January 17, 1989 (ST-HL-AE-2936.) Change bars have been added to highlight the revision to'the initial response.
p HL&P is planning to conduct reduced Reactor Coolant System (RCS) inventory operations during the upcoming refueling outage for Unit 1. The expeditious actions sud snhancenents as described in Atcachmente 2 and 3 will be completed as described Jr. Attachment 4, The attached response details nur commitments and actions to resolve t he concerns of the Generic Letter.
If you should. have any quest. ions on this matter, please contact l
g Mr. M. A. McBurnett at (512) 972-8530.
G. E. Vaughn
/
Vice President Nuclear Operatiors
[ GEV/GCS/n1
Attachment:
1 Backgrcund Figure 1: Reduced RCS 2 Expeditious Actio,s and Inventory I evel Responses In'iicatior 3 Enhancements and Responses 4 Generic Letter 88-17 Hardware Changes A Subsidiary of Houston Industries Incorporated NL.89.009.02
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- l. 11ouston 1.ighting & Power Compan)
L ST-HL-AE-3097
^ Pile No.s G3.8
. Page 2 cc Regional Administrator, Region IV Rufus S. Scott-Nuclear Regulatory Commission Associate General Counsel 611 Ryan Plaza. Drive, Suite 1000 Houston Lighting 6. Power Company Arlington,~TX 76011 P. 0. Box 1700 Houston, TX 77001 George Dick, Project Manager U. S. Nuclear Regulatory Commission INPO Vashington, DC 20555. Records Center.
1100 Circle 75 Parkway
. Jack E. Iess Atlanta, GA. 30339-3064' Senior Resident Inspector-Unit 1-c/o U. S.' Nuclear Regulatory Commission - Dr. Joseph M. Hendrie P. O. Bom. 910 _
50 Be11 port Lane Bay City, TX 77414 Be11 port, NY 11713 J. I. Tapia D. R. Lacker Senior Resident Inspector-Unit 2 Bureau of Radiation Control c/o U. S. Nuclear Regulatory Commission Texas Department of Health P. O. Box 910 1199 West 89th Street Bay City, TX 77414 Austin, TX 78756-3189 J. R. 'Newman, Esquire .
Newman & Maltzinger, P.C.,
1625 L Street, N.W.
Washin2 ton, DC '20036 R. L. Range /R, P. Verret Central Power & Light Compar.y P. O. Box 2121 Corpus Christi,.TX 78403 R. John Miner (2 copies)
Chief Operating Officer City of Austin Electric Utility'
.721.Barton .9prings Road Austin, TX 78704 R. J. Costello/M. T. Hardt City Publje Service Board ,
P. O. Box 1771 San Antonio, T*/ 79296 Revised 06/16/89 NL.DISR4
a UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION In the. Matter )
)
. Houston Lighting & Power ) Docket No. 50-498 Company, et al., ) Docket No. 50-499
)
South Texas Project )
Units 1 & 2 )
l' AFFIDAVIT G. E. Vaughn being duly sworn, hereby deposes and says that he im Vice President, Nuclear Operations of Houston Lighting & Power Company; that he is duly authorized to sign and file with the Nuclear Regulatory Commission the attached response to NRC Generic Letter 88-017; is familiar with the content thereof; and that.the matters set forth therein are true and correct to the best of his knowledge and belief.
G. E. ' Vaughn /
Vice President Nuclear Operations Subscribedunds7orntob,eforeme,aNotaryPublicinandforThe' State ' of Texas this JC day of /ha,z/Af _ _ ,1989.
SHARON DONAHY r Q d ,t # & M M.I u.
, gya p E #3 k U tary Publje in and for'tha #
State of Texas My Comm. Eo. Apr. 8.1991 l a ene:m e-d'"I i
NL.89.009.02 c_________-.. I
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Attachment 1 S7-HL-AE-3097 Page:1 of i South Texas Project Electric Generating Station Units 1 &.2 Docket Nos. STN 50-498, STN 50 499
-Response to F NRC Generic Letter 88-017: - " Loss of Decay Heat ' Removal"
Background
NRC Generic Letter 88-017 consolidates the industry.e.cperiance on the hazards
- of loss of ' Residual Heat Removal- (RHR), and stresses he nocess ity for-
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immediate. action in order to prevent loss of core coo: ling durir.g reduced RCS inventory operations. 'The conditions.under which the " expeditious. actions"
~ identified in the Generic Letter could apply at STPEG11 during the .first.
refueling outage (Reduced Reactor Coolant System (RCS} Opesations) consist of the followings a)~ irradiated fuel.is in the reactor vessel, and b) the reactor vessel water level is lower than 4.5 feet below the vessel flange. (A discussion on the selection of'this water level is provided in the response to expeditious action 4.)
For the Unit' 1 first refueling, Couth Texas Project plans to enter reduced RCS inventory operations for installation and reuoval of nozzla dams in all f our Steam Generators. The hardware and procedural changen required to support this effort will be in effect prior to entering reducno RC!: inventory operations. In addition, hardware changes associated with the programmed 1 enhancements and their associated procedural changes <thich are not completed for the first refueling will be iruplemented by the en:1 of the second refueling. Attachment 4 provides a summary of the ha rdwaro changes rsquired to support the response to this generic letter. If the plats to enter reduced RCS ir4ventory operations change, the schedule for implemen:Ing the respenres co NRC Generic Letter 88-017 will be changed accordingly.
Prior to redvaced RCS inventory operations on Unit 2, the hard'4are and procedural changes which are specified as expeditious action responses will be implemented. All hardware changes (both for expedit!.ots 44tions and
- programmed echarcements) will be implemented on Unit 2 prior to the end of the i first refueling outage.
Responses on each of the eight expeditious actions and six enhancements identified in the Generic Letter are provided as a final respor.se as follows:
Attachment 2 - Expeditious Actions and Respor ses Attachment 3 - Enhancements and Responses Attachment 4 - Generic Letter 88-17 Hardware Changes Figure 1 - Reduced RCS Inventory Level Indication NL.89.009.02
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.i Attachment 2. {
ST-ML-AE-3097 Page 1 of 7 Expeditious Actions and Responses Actions and Responses are provided as follows:
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.
Eesponse: To refresh personnel on the potential hazards and difficulties of reduced RCS inventory operations, Plant Operations shift personnel in the affected unit will be trained prior to entry into a reduced RCS inventory condition. A prerequisite has been added to the reduced RCS inventory operations procedure to complete this training prior to assuming the first shift assignment during reduced RCS inventory operations. As a minimum, the training will consist of a lesson plan with the following elements:
a) a discussion of the Diablo Canyon loss of RHR event, related events, lessons learned, and implications for the operator; b) a discussion of the South Texas Project Electric Generating Station modifications for enhanced temperature and level indication, including operational considerations; c) a review of the " Loss of RHR" (OPOPO4-RH-0301) off-normal procedure with specific emphasis on procedure changes since the last revision; d) the training conducted prior to commencing reduced RCS Inventory Operations will also include a discussioa of the necessity for auelyzing the expepted system respcats for a pisnned RCS perturbation, so th.t quick and effective counter measures can be taken if decay heat removal ability is L affected.
Action 2) Impisment proceduras and administrative controls that reasonably assure chet containmer.t closure will be achieved prier to the time at which a core uncoserf could result icom a lots cf RER, coupled with an inability te initiate siternate cooling or addition of water to the RCS Jeventory. Containment closure procedures shoald itelude consideration of pctertial steam and radioactive material release Tron the RCS should closure activities eFtend into the tim 0 boiling takes place within the RCS, Th2se ptacedures and administrative controls should be active and in use:
l a) prior to entering a reduced RCS inventory condition for Nuclear Steam Supply *=ystem (NSSS) supplied by Combustion Engineering or Westinghouse, and NL.89.009.02
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' Attachment 2 g o ST-HL-AE-3097 N Page 2 of 7 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 NSSS 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 applicable condition or maintain a closed containment.
Responses Prior to authorizing work start for an activity which involves a containment penetration, the following approval steps must be i- performed (as specified in OPGP03-ZO-0035 " Reduced RCS Inventory Operations"):
- 1) A written plan must be developed which specifies both the method of restoration and the individual responsible for the proposed breach.
- 2) 'The work scope must be reviewed by the Mid-Loop Coordinator (a dedicated licensed operator available on site 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> a day), who tracks each proposed breach in a manual log. As part of the review, the Mid-Loop Coordinator will verify that the time required for restoration is less than the time required to reach the boiling point in the RCS. (Time to boiling will be based on South Texas Project specific data contained in the Westinghouse Owner's Group study.)
- 3) The Shift Supervisor must concur with the Mid-Loop Coordinator's recommendation, and then approve the work to start.
In the event that the Shif t Supervisor decider that contaitraent closure is required, the responsible individual specified for each actite containment breach will be contacted. Where a containment {
brea:h will be more than oce shift, a responsible individual is identified for each day and each time period to close the breach.
All containment breaches will be restored as specified in their respective written plans, and progrees of restoration sill be tracked by the Mid-Loop Coordinator.
l The administrative controls described above will be in effect prior 1 to entering Reduced RCS Inventory Operations.
The " Loss of RHR" (OPOPO4-RH-0001) off normal procedure includes actions to be taken in the event that boilinF in the core starts prior to completing containment closure activities. )
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NL.89.009.02
. 1 Attachment 2 ST-KL-AE-3097 Page 3 of 7 Action 3)- Provide at least two independent, continuous temperature indications that are representative of the core exit conditions whenever the RCS in in a mid-loop condition and the reactor vessel head is in place. 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 locaticin outside of the containment building with prevision for providing immediate temperature values to en operator in the.CR if significant changes, occur. Observations should be recorded at an interval no greater than'15 minutes during normal conditions.
Response . Core exit temperature instrumentation is provided in the STPEGS design to meet the requirements of NUREG-0737, Item 11.F.2, and RG 1.97. This pa.rameter is displayed in the Control Room on the l Qualified Display Processing System (QDPS) and on Control Room analog recorders. The core exit temperature instrumentation is accurate over the range of concern-for Reduced RCS Inventory Operation. This system is described in detail in the STPEGS FSAR, Sections 7.5.6 and 7A.11.Y.2. Display of core exit temperature is also available in the Control Room on the Emergency Response Facilities Data Acquisition and Display System (ERFDADS) which la described in detail in FSAR Section 7.5.7.
The presently installed core exit temperature instrumentation vill be used to comply with the requirement of two independent, contsuucusly displayed temperature indications. The OPPS or ERFDADS dispinyt of core exit temperature will be continuously rivailaole whenever the RCS is in a mid-loop condition and the reactor vessel head is in place. A mf.nisaum of fiv2 cerc exit tLermecouples per train will be available as input to the CDPS or ERFDADS computer systems whenever the RCS is in a reduced RCS inventory operation and the reactor vessel head is in place. A permanent temperature recorder shewing representative high 7; temperature wii! provide an alarm af the core exit temperature
[g exacede a prascribel setpoint. Plant procedures will require core l exit temperature display, thermocouple, and alarm availability as 7-r prerequisite condition to enter reducen RCS inventory operation. l NL 89.009.02
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Attachment 2.
ST-HL-AE-3097
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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: Reactor vessel water level indication is provided in the STPEGS design to meet the requirements of NUREG-0737, Item 11.F.2, and RG 1.97. This parameter is displayed in the Control Room on QDPS and on analog recorders. This system is described in detail in the STPEGS FSAR, Sections 7.5.6 and 7A.11.F.2. Display of reactor vessel water level is also available in the Control Room on ERFDADS which is described in detail in FSAR Section 7.5.7.
As described in the FSAR, the redundantfreactor vessel water level (RVWL) sensors are discrete point sensors. Figure 1 provides a drawing of the vessel level indication for reduced RCS inventory operation. Reactor vessel plenum sensors are of particular importance in reduced RCS inventory operation. Point #2 is located 2 inches above the vessel flange. Point #3 is located at an elevation which is 4 1/2 feet below the reactor vessel flange and 1 1/2 feet above the top of the hot leg piping. Point #4 is loc ated at the elevation of the top of the hot leF piping. Toint (5 is located tt the elevation of the hot leg piping cerster line. Point i 44 corresponds to the top of the het leg narrow rar.ge instrument ,
I described talov.
i During the drasndoun operation for the first Unit I refueling outage when the reactor vessel level reaches the discrete point 4 1/2 ft below the flange, STPEGS procedures will require that prerequisites are tiet for entry into reduced RCS inventory operation. The RVFL System is a tellaole system for indication of entry into reduced RCS inventory operation. The RVWL eystem is not affected by pressure differences in the RCS system. A sight-glass or tygon hose level indication is affected by pressure differences in the RCS. Therefore, the RVWL discrete poir.t of 4 1/2 ft below the flange was chosen over a sight-glass or tygon level indication point.
NL.89.009.02
Attachment 2 ST-HL-AE-3097 Page 5 of 7 For the first refueling outage a tygon hose will be used as a:
backup level indication during drain-down. Prior to the second refueling outage for Unit 1 and the first refueling outage for Unit 2 the.tygon hose will be replaced with a sight-glass backup level indication for drain-down-of the RCS. The tygon hose (and permanent sight-glass) will-be located in a stairwell outside of the biological shield wall. The stairwell will be permanently marked with appropriate levels. (This is already complete in Unit 2.) Additionally, it should be noted that the STPEGS design of the hot leg location relative to the steam generator nozzles allows reduced RCS inventory operation at levels 8 to 11 inches above the middle of the hot legs. This allows the necessary evolutions to be performed at higher water levels when compared to other plant designs without spilling water into an open steam generator nozzle.
Promptly after shutdown, for the first refueling and prior to reduced RCS inventory operations, the following modification will be installed and tested. Narrow range leve1' instruments will be added to the RCS hot leg loops A and C. These loops have existing top entry primary sample connections which are available for the upper level taps. These loops also have 8" Safety Injection (SI/ hot leg) lines which connect to the 29" RCS hot' legs at a 90 degree angle to the hot leg vertical. This places the SI hot leg nozzles 14 1/2 inches above the bottom of the RCS hot leg. The SI lines have drain connections which are available for the lower level tap.
The 12" Residual Heat Removal (RHR) suction lines are on the opposite side of the RCS pipa in proximicy to the hot leg SI injection nozzle and connect to the RCS piping at 45 degrees below the horizos,tal. This arrangement wilJ ptovide an 18" level range from the top of the RCS hot leg pipe (+14-1/2") to 3-1/2" below the centerline of the RCS hot leg piping. This measurement location is in that portion of the hot leg piping of most concern for level control (see Figure 1.)
The topo dateribed above on the RCS hot lege A and C will be used to connect two local sight-glasses (1 per loop) and differentici pressure levol transmitters (1 per Joop) for remote indications and an alarra in the Cootrol 2oo.n.
I TV Cameras will ba provided for monitorirg LCS level as indicated by sight-glass and/or Tygon tube levels as ALARA considerations require.
NL.89.009.02
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Attachment 2 ST-HL-AE-3097 Page 6 of 7 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 RHR should such a loss occur.
Response: RCS perturbations will be controlled and limited by the Plant Operating Procedure controlling reduced RCS inventory operations. l Examples of the type of controls which are in this procedure are:
limitations on surveillance, maintenance work, and lineups on the RHR system and its supporting systems. The Mid Loop Coordinator and the Shift Supervisor will review maintenance work activities and surveillance to ensure RCS perturbations are avoided.
Electrical power to RHR and its support systems will be maintained by careful selection of outage times and implementation method.
Instrument air work activities will be minimized to ensure instrument air availability will be maintained. Calibration work on all associated instrumentation will be minimized to ensure that the operator is constantly updated on system parameters. The computer support systems (ERFDADS/QDPS) will be maintained as necessary to provide the temperature and level indications as listed above.
For the first refueling outage on Unit 1, current plans include a temporary modification to provide RHR pump motor current indication for the Control Room operator and a permanent modification to provide motor current at a later date. Also a temporary modification to remove the RHR Auto Closure Interlock is plar.ned on Unit I for refueling outage one. (See Attachment 4.)
NL.89.009.02
Attachment 2 ST-HL-AE-3097 Page 7 of 7 Action 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 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: The STPEGS design utilizes only dedicated RHR pumps for decay heat removal. Separate pumps are utilized for low head injection and high head injection. At least two separate means of water inventory addition will be available at all times. Inventory addition instructions have been developed to specify the addition methods which are prerequisite to reduced RCS inventory operations.
Instructions for the use of either two Low Head Safety Injection i pumps or a Low Head Safety Injection Pump and a Centrifugal Charging pump have been developed to provide controlled level recovery. Additional instructions have been added to ensure that the flow path will not bypass the reactor vessel. Administrative Controls have been established to ensure that the necessary pumps are operable during reduced RCS inventory operations.
Action 7) 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 Reactor Vessel (RV).
Response Steam Generator nozzle dam and primary manway installation and removal sequence will oe controlled to provide adequate vent capability of the RCS hot leg by use of a Maintenance Department procedure.
Action 8) (Applicable co NSSSs with loop Ltop valves) Implement procedures and administrative controls that reasonably assure that n11 hot legs are not blocked almultaneously by closed stop valves unless a vent path ic provided that is large enough to prevent pressurization of the RV upper plenum or unless the RCS configuration prevents RV water lows if RV pressurization should occur. Closing cold legs by nozzle dams dces not meet this condition.
Response: Since the South Texas Project Reactor Coolant System has no loop stop valves, no action will be required on this expeditious action.
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Attachment 3 ST-HL-AE-3097 Page 1 of 5 Enhancements and Responses The following responses to each of the six programmed enhancements identified in the Generic Letter are provided:
Enhancement 1) Instrumentation Provide reliable indication of parameters that describe the state of the RCS and the performance of systems normally used to cool the RCS for both normal and accident conditions. At a minimum, provide the following in the CR:
(a) two independent RCS level indications (b) at least two independent temperature measurements representative of the core exit whenever the 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 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 DHR system performance Response: The existing core exit temperature indications described in the expeditious action response for RCS temperature are considered adequate for this mode of operation.
Additionally, RV plenum outlet temperature indication is l available via the ERFDADS from the RVWL system parameters.
The ERFDADS computer displays the unheated junction l thermocouple at the discrete sensor points used for RV level indication.
Long term plans for reduced RCS inventory operation level {
indication are as described in expeditious action 4 of Attachment 2 with the exception that the tygon tubing will be replaced by a permanent sight-glass. (see Figure 1.)
The two narrow ranfe hot leg level instruments described in the expeditious action response will be permanently wired to display and alarm instrumentation in the control room. The level transmitters and sight-glasses will be connected to the hot leg taps and calibrated prior to entering reduced inventory operation. When not in use for level indication, I these instrument sensing lines will be isolated from the RCS loops.
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E u Attachment'3 ST-HL-AE-3097 Page 2 of 5 l
- The existing RHR instrumentation includes:. heat exchanger inlet and outlet temperature, RHR pump discharge pressure-and pump discharge flow.- RHR pump motor current indication does not exist in.the present: design. RHR pump motor current Indication will.be -l added on control room displays to provide the control room 1 i operators with indication and alarm of the approach to inadequate-pump suction conditions. For the'first refueling for Unit One, a-
' temporary modification will be installed to provide current-indication to the operator.
A new integrated RHR performance display will be developed for the reduced inventory mode of operation. This ERFDADS display will contain the RHR parameters described ~above as well as RV level,; hot
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leg levels and core exit temperatures. The RHR pump motor current will not be displayed on this display since the computer scan rate is not. sufficient to allow detection of rapidIy changing motor current.
The new displays.and control board modifications will be accomplished within the Control Room Design Review Program.
Enhancement 2)- Procedures Develop and implement procedures that cover reduced inventory operation and that provide an adequate basis for entry into a reduced inventory condition. These includes (a) procedures that cover normal operation of the NSSS, the containment, and supporting systems under conditions for which cooling would normally be provided by DHR systersu. R (b) procedures that cover emergency, abnormal, off-normal, or the equivalent operation of the NSSS, the containment, and supporting systems if an off-normal conditios occurs while operating under conditions for which cooling would norna11y be provided by DHR systems.
(c) administrative controls that support and supplement the procedures in items (a), (b), and all other actions ideratified in this communication, as appropriate.
NL.89.009.02
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f Attachment 3
.ST-HL-AE-3097 Page 3 of 5 t
Response: Procedural control will be established as follows:
As described in the expeditious action response, a Plant Operating Procedure has been developed.which will provide overall guidance on the prerequisites for entry, operation, and' exit from reduced RCS inventory conditions. Required-actions and precautions are also delineated in this procedure. Procedures which cover normal operations during decay heat removal by RHR have.been reviewed to ensure compatibility with.the above procedure and proper sequencing such that a smooth transition to reduced inventory operations can be accomplished.
The " Loss of RHR" off-normal procedure provides instructions and actions for the recovery from.a loss of decay heat removal, including back up sources and their priority.
A closed containment will be verified prior to entry into
. reduced RCS inventory operations. During reduced RCS inventory operation containment breaches will be tracked as, described in the expeditious action response.
In addition, administrative controls that support the procedures listed toove have been reviewed to provide a smooth transition to reduced RCS inventory operations.
Enhancement 3) Equipment
.(a) Assure that adequate operating, operable, ard/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 includo at least one high pressure injection pump and one other system. The water addition rate capable of beirg provided by each equipment item should be at least sufficient to keep the core covered.
(c) Provide adequate equipment for personnel communications that involve activities related to the-RCS or systems necessary to maintain the RCS in a stable and controlled condition.
NL.89.009.02
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Attachment 3 ll ST-HL-AE-3097
- Page 4 of 5 Response: Since the RHR cystem, Low Head Safety Injection _ (LHSI) system, and the Centrifugal Charging Pumps are all safety ,
related and powered by-1E power sources, these systems provide a very high degree of reliability already.- Technical Specifications do not require that the RHR' Auto Closure Interlock be operable during reduced RCS inventory operation.
'A temporarf ecGification will be installed to inhibit the Auto Closure Interlock during reduced inventory operation.
Permanent deletion of the RHR Auto' Closure Interlock is being evaluated. Present Technical Specification requirements'for' the availability of RHR and Chemical and Volume Control System (CVCS) pumps combined with administrative requirements for the availability of LHSI pumps will ensure.that an adequate and reliable inventory addition and decay heat' removal capacity remains continuously available during reduced RCS inventory operations.
Communications via the plant public address system.. hand held' radio, and sound powered phone circuits are available for control of evolutions. Appropriate use of.these means of co:nmunications will ensure Control Room personnel are fully-appraised of the status of the RCS.
Enhancement 4) Analyser Conduct antlyses to suppleme;st existing information and devalop a basis fer procedures, instrumentation installation and response, and equipment /NSFS interactions and response.
The analyses should encompass thermodynamic ar.d physical q' (configuration) states to which the hardware can be subjected and should provide sufficient depth that the basic is developed. Emphasis should be placed upon obtaining a complete understanding of NSSS behavior under nonpower operation.
NL.89.009.02
Attachment 3 ST-HL-AE-3097 Page 5 of 5 Response: WCAP 11916 (developed by the Westinghouse Owner's Group) provides the analysis which was used to develop procedures l and an understanding of RCS behavior under loss of RHR during reduced inventory conditions. In addition, Westinghouse has performed a plant specific analysis for operation at reduced RHR pump flowrates to increase the margin to vortex formation during reduced inventory operations. The South Texas Project design allows draining of the primary side of the Steam Generator to a level below the top of the RCS hot leg piping for manway removal and nozzle dam installation. The steam generator tubes can be drained without draining the hot legs to the middle of the hot leg piping. This will allow operation with sufficient margin prior to air entrainment and provide a longer period of time for operator recovery from inadvertent inventory losses before vortexing occurs. The Westinghouse Owner's Group report WCAP-12111 (RCS Level Gradients) has also been reviewed to gain an understanding of potential level variations between the RCS hot leg at the RHR pump suction piping and other points in the RCS. This data-was used to establish a minimum requirement for various flowrates, and to establish procedural action levels and alarm setpoints.
Enhancement 5) Technical Specifications Technical specifications that restrict or limit the safety benefit of the actions identified la this letter should be identified and appropriate changes should be submitted-Response: As indicated in the above responses, a Technical Specification change is being evaluated to delete the Auto Clocure Int erlock.
Enhancement 6) RCS perturbations i
Item (5) of the expeditious actions should be reexamined and 1 operations refined as necessary to reasonably minimize the likelihood of loss of DHR. .
Response As part of the continuing review of industry and plant problems with reduced RCS inventory operations, and as a result of procedural reviews and upgrades, further '
instructions will be provided to operations to limit the frequency and severity of RCS perturbations.
NL.89.009.02 L _ -_ . - -_ a
. m-L Attachment 4 ST-HL-AE-3097 Page 1 of 2 Generic Letter 88-17 Hardware Changes C Expeditious- Description of Hardware Change Unit 1 Unit 2
-Action Schedule Schedule l' None NA NA' 2 None NA NA 3 Core exit temperature recorder. Note 1- Note 1 and alarm 4 a. ' Hot leg narrow range level Note 1- . Note 1 Indication, level transmitter tubing, alarm window and level recorder.
- b. Hot leg narrow range Note 1 Note 1
-sight-glass, tubing and valves
- c. Tygon hose, level indication ~ Note 1 Note'l markings for drain-down level indication
,. d. Perar.nert vir,ht-glass (in lieu if RFQ2* RF01 1
tygen) for drain-down level irdication 5 a. RHR pump motor current Note 1 N/A Jndication, temporr.ry modification
- b. RHR Auto Closure Interlock, Note 1 Note I temporary Modification 6 None NA NA 7 Pone NA NA 8 NA NA NA Note la Prior to the first reduced RCS inventory operatica.
- Refueling Outage 2 NL.89.009.02
-i - , .,.
1 \ -. ;n Attachment 4~
ST-HL-AE-3097-Page 2 of 2' Enhancements Description of Hardware Change Unit 1 Unit 2 Schedule Schedule 1 .a. ' Narrow Range Hot Leg Level- Note 1 Note 1 Instruments
^
- b. Permanent RHR Eump Motor .RF02 RF01
' Current Indication
- c. Integrated RHR Performance RF02 RF01'-
Display 2 None NA NA-i 3 None NA NA 4 None NA NA 5 None NA NA 6 None NA NA Note Is Prict to the first reduced RCS Inventory operation.
O i
t 1
i l
l NL.89.009.02
7
(. ; } > . P
'Rsditced RCS Inventory Level ~ Indication
['
~
.' Figure 1 e
' Lr k . To The' Pressurizer-
',+ - Vent-RVWLS-if/ . Heated Junction jk-Thermocouple '
(Typical.of 2)
+. 2 Gloss:
7 Pt20 - 2" .-
.(Tygon for' RF91) 4 4.5 *
. .k
,Pt3oJ 1.5
- Pt4 o____ ' *^
- See Crossectional-Pt 5 0- - - - - - - View A-A Below Hot 4 A leg Cross
@ Under p w
(C s Y
h I X Reactor
.+ Coc.lont .
Drain Tonk j
Crossectional View A-A (Hot . Leg Narrow Range Level Indication)
To Primary (Typico! of 2)
Sampling Ak 1
s ~_~C injhbborL ^^^^^'* : InsY j m A
(-) Hot > - -- --> CRFDADS Computer v=3=
+,
Leg
's RHf3 ~k r Suction Recorder LT > Annuciotor Level Transmitter
_ _ - - _ _ _ _ _ _ _ _ _ _ - _ _ _ _ _ _ _ - _ - - - - - - . _ _ _ _ _ - - - _ _ _ - _ _