ML20065T513

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Application for Amends to Licenses NPF-76 & NPF-80,changing Tech Specs 3/4.4.4 & 3/4.4.9.3 Per Generic Ltr 90-06 & Generic Issues 70 & 94 Re PORV & Block Valve Reliability
ML20065T513
Person / Time
Site: South Texas  STP Nuclear Operating Company icon.png
Issue date: 12/21/1990
From: Rosen S
HOUSTON LIGHTING & POWER CO.
To:
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20065T515 List:
References
REF-GTECI-070, REF-GTECI-094, REF-GTECI-NI, RTR-NUREG-1326, TASK-070, TASK-094, TASK-70, TASK-94, TASK-OR GL-90-06, GL-90-6, ST-HL-AE-3642, NUDOCS 9012280165
Download: ML20065T513 (15)
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Text

{{#Wiki_filter:, .. s , The Light company "" """*'""' "* O II lloui. ton Lighting & Power December 21, 19 s ST HL AE 3642 File N..: C9.06, G20.01 10CFR50.90 10CFR50.92 100FR50.54(f) U. S. Nucl ar Regulatory Commission Attention: Document Control Desk Washingt..., DC 20555 South Texas Project Electric Generating Station Units 1 6 2 Docket Nos. STN 50 498, STN 50 499 Proposed Amendment to the Unit 1 and Unit 2 Technical Specifications 3/4.4.4 and 3/4.4.9.3 Pursuant to 10CFR50.90, llouston Lighting & Power Company (Ill4P) hereby proposes to amend its Operating Licenses NPF 76 and NPF-80 by incorporating the attached proposed change to the Technical Specifications for the South Texas Project Electric Generating Station (STPEGS) Units 1 and 2. Based on technical studies for GI 70 (NUREG 1316) and GI 94 (NUREG 1326), pursuant to 10CFR50.54(f) the staff requested that actions identified in Generic Letter 90 06, Enclosure (s) A and B of Section 3, be taken by licensees in order to increase plant safety and reliability. Implementation of the 10CFR50.54(f) request requires lilAP to modify Technical Specifications 3/4.4.4 and 3/4.4.9.3. Attached 19 the proposed change to the STPEGS Technical Specifications. In addition, changes to allow verification of PORV operability during MODES S 

       & 6 are included, llIAP has reviewed the proposed amendment pursuant to 10CFR50.92 and determined that it does not involve a significant hazards consideration. The basis for this determination is provided in the attachments.                    In addition, based on the information contained in this submittal and in the NRC Final Environmental Statement related to the operation of STPECS Units 1 and 2, llL&P has concluded that, pursuant to 10CFR51, there are no significant radiological or non radiological impacts associated with the proposed action and the proposed license amendment will not have a significant effect on the quality of the environment.

The STPEGS Nucicar Safety Review Board has reviewed and approved the proposed changes, n/cas.no A Subsidiary of Ilouston Industries incorporated 0 9012280165 901221 ' PDR ADOCK 0500 P

l Ilouston Lighting & Power Company South Texas Project Electric Generating Station ST llL AE 3642 File No.: C9.06, C20.01 Page 2 In accordance with 10CFR50.91(b), lil4P is providing the State of Texas with a co of this proposed amendment. 1 If you should have any questions concerning this matter, please contact i Mr. A. W liarrison at (512) 972 7298 or myself at (512) 972 7138. ) c S. L. Rosen Vice President, Nuclear Engineering SDP/sgs Attachments: 1. Proposed Technical Specification Changes

2. Significant llazards Evaluation c

A1/038.N19 

        *   '                                                                                                                                                                             ST-HL AE 3642 liouston Lighting & Power Company              ,                                                                                                         rile No.: G9.06, C20.01 South Texas Project Electric Generating Staaon p,gg 3 cc:

Regional Administrator, Region IV Rufus S. Scott Nuclear Regulatory Commission Associate General Counsel 611 Ryan Plaza Drive, Suite 1000 Houston Lighting & Power Company Arlington, TX 76011 P. O. Box 61867 Houston, TX 77208 Coorge Dick, Project Manager U.S. Nuclear Regulatory Commission INPO Washington, DC 20555 Records Center 1100 Circle 75 Parkway J. 1. Tapia Atlanta, CA 30339-3064 Genior Resident inspector c/o U. S. Nuclear Regulatory Dr. Joseph M. Hendrie Commission 50 Be11 port lene P. O. Box 910 Be11 port, NY 117'53 Bay City, TX 77414 D. K. Lacker J. R. Newman, Esquire Bureau of Radiation Control Nnwman & Holtzinger, P.C. Texas Department of Health 111F L Street, N.W. 1100 West 49th Street Washingcon, DC 20036 Austin, TX 78756-3189 R. P. Verret/D. E. Ward Central Power & Light Company P. O. Box 2121 Corpus Christi, TX 78403 J. C. Lanier/M B. Lee City of Austin Electric Utility Department P.O. Box 1088 Austin, TX 78767 R. J. Costello/M T. Hardt City Public Service Board 1 P. O. Box 1771 San Antonio,-TX 78296 Revised 10/08/90 L4/NRC/

t . ( , UNITED STATES OF AMERICA 

                                                            ' NUCLEAR RECULATORY COMMISSION In the matter                                                         )
                                                                                      )
               ; Houston Lighting & Power                                            .)          ~ Dock Nos. 50 498 Company,-et al.,         .                                            )                           50 499
                                                                                      )

South Texas Project ) Units 1 and 2 ) AFFIDAVIT S.'L'. Rosen-being duly sworn, hereby deposes and says that he is 

              -Vice President,- Nuclear Engineeri ng of :louston L ihi                       g t ng & Power Coepany; t hat    .
             ' he is-duly authorized to sign and file-with the Nuclear Regulatory Commission-
the Proposed Amendment-to the Unit 1 and. Unit 2 Technical-Specifications 3/4.4.4 and 3/4.4~.9.3; is familiar with the content'thereof; and.that the matters see . forth therein 'are true and correct to the best of his knowledge
               -and belief.
                                                                                               <         3' S7L. Rosen                                          i
                                                                                           -Vice President, Nuclear Engineering
              , STATE OP TEXAS )
                                           ).
                                           -)

l Subscribed a d sworn to before me, s Notary Public-in-and'for: - The. State of: Texas thiso7$yday of /)Ecor/M/uf' , 1990, 1 

                                            - _ :mn Ay            .su my heim hans 1.In1 14us-                            M//[e5                  46[k
                           .,, ,, f                                                         Notary Public in and for the-
                                                          - - =                              State-of Texas Y

A1/038 N19

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     ;r      i' s

Attachment 1 ST HL-AE 3642 Page 1-of 11 PROPOSED TECHNICAL SPECIFICATION CHANGES 

                      . The proposed changes made-to the current STPEGS Technical Specifications incorporate the recommendations provided in Enclosure A and Enclosure B of Generic Letter 90 06. Changes to improve clarity-and accuracy of the                                             1 1 Technical Specifications are also included'. Additional changes are included to' allow verification of PORV operability during MODES 5 & 6.

CHANGES IN RESPONSE TO GL 90-06 RESCRIPTION OF CRANGES AND JUSTIFICATION Technical Specification 3/4.4.4 

                                   .LCO-3.4.4:

The Limiting Condition for Operation statement is clarified by replacing  ; 

                                    -"All" with "Both" since the STPEGS COMS system consists of tso I                   "is .

Justification: This change .is in accordance with Attachment A-1 of Generic Letter 90-06 ' and the STPEGS plant deaign. 

                                   . Action (a.):
                                  'The action statement is clarified by changing "more" to "both" since only.                            j two PORVs;are provided in the design. . The statement "with power                                   :-!

g -maintained to the-block-valve (s)" is added. .The requirement to reach 

                                     " COLD. SHUTDOWN within the following 30 hours"'is changed to " HOT SHUTDOWN

'~ i within.the following 6 hours". 

                                  ' Justification:                                                                                        -1 Changes to Action _(a.)'are consistent with the guidance provided in:

E ' -Generic Lettet'90-06 , t 

                                  ' Action (b.):

Thc requirement to reach " COLD SHUTDOWN within 30-hours" is changed to L B " HOT SHUTDOWN.within 6 hours" in accordance with Generic'Lett r 90 06, l-Justification: This change is consistent with the guidance provided in ceneric K[ Letter-90 06. Action-(c.): line requirement to r' ach " COLD SHUTDOWN within 30 hours". is changed to. 

                                    '" HOT SHUTDOWN =within 6 hours" in accordance with-Generic Letter.90-06.
                                    .In addition,cthe reference to "PORV(s)" and " valve (s)" is changed'to
                                    ."PORVs" and " valves" since this action only applies.when both PORVs are
                                    -inoperable. The statement'"within i hour either restore each of'the PORVs" is unchanaed. Fenm the current STPECS Technical Specifications.

l . Justification: This change is consistent with the guidance provided in R Generic Letter 90 06. The use of "PORVs and valves" instead of "PORV(s) 1. A1/d38N19

Attachment 1 ST-HL AE-3642 Page 2 of 11 and valve (s)" improves clarity since this action is applicable only to the case when both PORVs are inoperable, The recommended Technical Specification changes provided in Attachment A 1 to the Generic Letter states that "within 1 hour restore at least one PORV", The intent of this action is to provide for the removal of power from a closed block valve as additional assurance to preclude any inadvertent opening of a block valve at a time when the PORV may not be closed due to maintenance to restore it to operable condition. Since the entry condition for this action statement is both PORVs inoperable, it follows that each should be restored within 1 hour or their block valves closed, Action (d.): This action applies to the case when one block valve is inoperable and is the result of splitting the previous Technical Specification action (d.) into two action statements for clarity. The PORVs are to be placed in 

            " closed position" rather than " manual control" as recommended in the Generic Letter, Justification:

This change is made to provide an action statement applicabic to one block valve inoperable and an action statement applicable to two block valves inoperable. This improves clarity and is consistent with the guidance provided in Generic Letter 90 06, Placing the valves in " closed position" rather than " manual control" is appropriate since this action is required to prevent the automatic opening of the PORVs which is the intent of the step in the recommended Technical Specification change. Action (e.): This action applies to the ecse when both block valves are inoperable and incorporates the guidance provided in the Generic Letter. Justification: This change-is made to provide an action statement applicable to one block valve inoperable and an action statement applicable to two block valves inoperable. This improves clarity and is consistent with the guidance provided in Generic letter 90 06. Surveillance Requirement 4,4,4,1 a: The statement "on the PORV actuation channel" is added to address the Generic Letter requirement. Justification: This change is consistent with the guidance provided in Generic Letter 90-06 and provides consistency with Surveillance Requirement 4.4,9,3,1.b.. A1/038.H10 

                                                                                                                              ]

l 

                                                                                            . Attachment 1 ST HL-AE 3642                 ..

Page 3.of 11 l 

                                                                              ~

Surveillance. Requirement 4.4.4.1.b: The statement "during MODES 3, 4, or 5" is incorporated. Just1fication: This change.is consistent with the guidance provided in Generic Letter 90 06 in that testing is performed prior to establishing conditions where- j the PORVs are used for. low temperature. overpressure protection but-not' during power operations. The addition of MODE 5 to this surveillance requirement;provides additional operational flexibility in the .! performance of the. required test. l Surveillance. Requirement ' 4.4,4. 2 : The statement "with' power removed" is.-deleted. Jus'tification: This' statement is not required since=it.is incorporated into the

requirements of ACTION b. and c. 'of specification 3.4.4. .This change.is consistent with the guidance provided in Generic Letter 90-06.

4 Generic Letter Surveillance Requirement 4.4.4.3: Surveillance. Requirement 4- 4.4.3, provided in_ the Generic Letter,--is not incorporated.  ! 

                          ' Justification:                                                                                     j This Surveillance Requirement is provided in the Generic Letter to require . testing of emergency (backup) power supplies for plants -with non-                      3' Esafety. grade power. This surveillance requirement is not included in the STPEGS: Technical Specifications since the STPEGS PORVs:are-normally~                              ,
                           . powered from class 1E buses.                                                                      i s
                          . Generic Letter Surveillance Requirement 4.:4.4.1.b:
                                                                                                                               )

Surveillance Requirement. 4,4. 4.1.b. as provided. in; the Technical = 

                           ; Specification changes recommended-by Generic Letter 90-06 is-not-incorporated .    .
                           -Justification:

This. Surveillance ~ Requirement applies;to plants with air operated PORVs. - This!isinot applicable'to'STPEGS since solenoid operated-PORV are 

                          . installed.

f Technical. Specification 3/4.4.9-Surveillance Requirement 4.4.9'.1. 2 : j; ' Technical Specification figure.3.4-4'is added to the listing of.. figures - L to be updated based on the results of the RPV irradiation surveillance' !. . program. V 4 A1/038.N19 m . . _ . . . , _ _ . . . - . - - _ - . - . . _ _ - . . - ._- - . - i 

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                                                                                                                                  \

Attachment 1 

                                                                                        'ST-HL AE-3642 Page 4 of 11 Justification:
                          .The change is made to. emphasize the need to update.the figure and the allowable'PORV setpoint based on results of the RPV irradiation surveillance program.

LTechnical Specification-3.4.9.3 Limiting Condition for Operation 3.4.9.3: . This LCO is unchanged from the current STPEGS Technical Specification. The Generic Letter recommendation to include the~PORV setpoint in the LCO is not incorporated. i Justification: . . . This; format provides'the same information as-the LCO provided in the 

                         ' Generic Letter while enhancing clarity.       In addition the specification of thoLPORV lift setting within the-LCO, as in the Generic' Letter, could require future; revision to-accommodate changes in the.PORV setpoint1 resulting: from- the RPV irradiation- surveillance program.-

Instead of specifying the = specific setpoint in the LCO as in~ the -Generic Letter, the iSTPEGS-LC0iprovides a refcrence to. figure'3.4-4.: This: complies ~with the r 

                         . intent of the Generic L'cter.

LApplicability: [ The MODE 6 applicability of.this Technical Specification'is changed.to 4 "when the head'is on the. reactor vessel" to improv- -larity. 'The MODE 4  ! applicability provided in the Generic Letter, "wher le temperature of 7 

                         .any: RCS cold leg islless than or equal to (275*F]", is' not incorporated.                            !

The additional MODE'6 applicability restriction provided in the Generic 

                          -Letter, "and:the RCS is not vented through a                 square inch or larger                'i
                       . vent",'iscnot; incorporated.

1 Justification: The'HODE 4' applicability restriction to RCS temperatures less'than-or equal to. 275"E is omitted because MODE 4 is defined to be. an average. RCS temperature of 350"F 'or less which is the temperature at which the PORVs L are' manually armed.- The MODE 6 applicability restriction'is not incorporated because this . restriction :is <provided in the LCO. 

                        .Act' ion (a.):

The clarification, "in MODE 4",-is:added-in accordance with the Generic Letter to: clarify that this ACTION is applicable only to MODE 4 operations. 

                        ' Justification:

JThis change is consistent with the guidance provided in Generic Letter. 90 06. i At/036.N10

W

  • Attachment 1 ST HL AE 3642 Page 5 of 11 Action (b.):

A new action (b.) is added to the STPECS Technical Specifications. The action (b.) provided in the Ceneric Letter for MODES 5-6 6 is incorporated directly into the STPEGS Technical Specifications. The only changes from the recommended action-are the deletion of step numbers, the inclusion of the plant specific vent sire, and the use of "the next 8 hours" instead of "a total of 32-hours", 

                            . Justification:                                       ..

These changes improve clarity and increese the accuracy = of the Technical Specification.. These changes are consistent with the guidance provided 

                             'in Generic Letter 90 06, Action (c.):
                            .This action was previously action (b.) and has been renumbered only.
                             . Action.(d.):                                      .                    _

This action was previously action (c').and has been renumbered only, 

                             . Action (e,):                                                                                l
                            . This ' action wa's not previously included in this Technical Specification                   l land is being incorporated now to comply with the recommendations of the-l Generic Letter.                                                                              ,

Justification: LThis change'is consistent with the' guidance provided in Generic Letter 90 06. Note:' ' 

                             .A note-concerning the._ application of actions-(b.)-and (c.) has been added
                              .to allow; functional testing _-to' verify'PORV operability.

i 

                             " Jus tification: -
                            - Detailed justification for the proposed verification- of. PORV operability
is provided~in Enclosure 1.
                      -Bases 3/4,4.94 Low Temperature Overoressure Protection iTho'Lpw Temocrature Overoressure Protection Bases is' revised to add "u * .

details concerning-the-use of RHR relief valves to provide COMS during 

                              -the stroke-testing-of-inoperable PORV(s).

s 

                            -Justification:

Detailed justification for the proposed verification-of PORV operability. is provided in Enclosure 1, i 

                     . A1/038.N19

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       .         E
                                                                                                              ' Attachment 1-ST HL.AE 3642 Page 6 of 11 ENCLOSURE 1 VERIFICATION OF PORV OPERABILITY
                     ' BACKGROUND:

Technical' Specification 3/4.4.9, Pressure / Temperature Limits Reactor Coolant System, establishes the limiting Reactor Coolant System-(RCS) pressure and temperature-for all operating modes. The requirements for the overpressure 

                     -protection systems are Biven in Limiting Condition for. Operation (LCO) 3.4.9.3. This LCO stetes that two power-operated relief valves (PORVs) are to
                      ~be operable during modes 4 & 5, and mode 6 with the head on the reactor vessel, or the RCS be depressurized with an RCS vent of greater than or equal

, to 2.0 square inches. Action a. of this LCO states that with one PORV i inoperable, the inoperable PORV is to be restored to OPERABLE status.within 7 days _'or the Reactor Pressure Vessel _-(RPV) is to be_depressurized and vented-through a 2.0 square inch vent within the next-8 hours. Action b, of this LCO states that with both PORVs inoperable, depressurization and venting of the RCS through a 2.0 square inch vent is required within 8 hours. E Pressurizing;the RCS to stroke test a Pressurizer PORV following the L performance .of required ' maintenance or repairs as required by Technical Specification _4.0i5 createsia conflict with Technical Specification 3.4.9.3-requirements since a nominal test pressure'is required to overcome the- 

                      ' internal spring. pressure 'of the solenoid operated PORVs. The conflicting H                        requirements were identified and reported to'the NRC following'a Unit 1-
                                               ~

a L refueling outage (ref. 1). The required test provides verification'of valve operability in accordance l' with the1ASME code requirements. This proposed' test complies with the 

                     ; requirements ofotechnical-Specification 4.0.5.and the-intent of Generic ~ Letter-90-06 L(ref. :2) . Prior to this -test the ANALOG CHANNEL OPERATIONAL TEST :
                                                                                  ~

tL specified. in. surveillance requirement 4.4.9.3.1.a would be ' performed to-L cprovide reasonable assurance that-the adminirtratively' declared-inoperable s PORV will function-if required. _The ASME operability test cannot be performed-Lwithout suspending the requirement to depressurize and vent the RPV if one or both;PORVs are inoperable since--a. nominal reactor coolant system pressure is 

          =

Lnecessary to: perform the test. To resolve this conflict, HL&P requests that the requirement to depressurize and v'ent the RCS if one PORV is inoperable 

                      '(LCO 3.4;9.3.a).be waived for the-duration'of the-required test (not to exceed 7-days). ;A.similar change to LC0~ Action 3.4.9.3.b is requested for-the case
                     .when two PORVs are inoperable.

During-the-test interval, the possibility of a= cold-overpressure event will b_e minimized by administrative' controls and the i l consequences-of an overpressure transient will be mitigated by use of twozRHR-discharge relief valves or one.RHR discharge relief valve and one operable PORV. 

                                 ~

A1/038,N19 ,

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Attachment 1 ST-HL AE-3642 Page 7 of 11 TECHNICAL SPECIFICATION REOUIREMENTS: , Technical Specification 3/4.4.9, Pressure / Temperature Limits Reactor Coolant System, provides within LCO 3.4.9.3 the basic operability requirements for mitigating the effects of cold overpressure events. LCO 3.4.9.3 action statements. a. and b. require that if either or both of the PORVs are inoperable for longer than the allowable outage time, then the RCS must be depressurized and vented through a vent of at least 2.0 square inches. Surveillance Requirement (SR) 4.4.9.3.1.a requires the performance of an ANALOG CHANNEL OPERATIONAL TEST on the PORV actuation channel, but excluding valve operation, prior to entering an operating regime in which cold overpressure protection may be required and every 31 days thereafter. JUSTIFICATION FOR PROPOSED TEST METHOD: Branch Technical Position RSB 5 2 requires that the cold overpressure mitigation (COM) system operational readiness be demonstrated by the performance of testing as follows:

a. Testing of the system electronics to assure opetability prior to each shutdown,
b. Valve operability testing in accordance with ASME Code Section XI,
c. Subsequent to system, valve, or electronics maintenance, a test on that portion (s) of the system must be performed prior to declaring the system operational.

The design of the STPEGS COM system complies with all requirements of the Branch Technical Position except for the ability to perform a complete operational test following maintenance. If one or both PORVs are removed from service for the performance of required maintenance or repairs, a conflict - with the Technical Specification requirements is created since a nominal test pressure (i.e...RCS pressure) is required to overcome the internal spring-pressure of the solenoid operated PORVs. The proposed changes to the requirements of Technical Specification Actions 3.4.9.3 (a) and 3.4.9.3 (b.) would allow suspending the requirement to depressurize and vent the RPV if one or both PORVs are inoperable for the period necessary.to perform the required operability verification test. Prior to the performance of the operability test, the ANALOG CHANNEL OPERATIONAL TEST for the inoperable PORV(s) would be performed in ancordance with surveillance requirement 4.4.9.3.1.a to provide reasonable assurance that the PORV(s) would operate, if required, to mitigate an overpressure transient during the test period. In addition to this. precaution, two RHR discharge relief valves associated with two OPERABLE and operating RHR loops would be utilized to mitigate the effects of a cold overpressure event'if both PORVs are inoperable. In the event that only-one PORV is inoperable, the remaining OPERABLE PORV would be available to mitigate the effects of a cold overpressure event in addition to one RHR relief valve. As a result, cold overpressure protection is provided during the testing of A1/038.N19

1 t m. i e Attachment 1 ST HL AE 3642 Page 8 of 11 the inoperable PORV(s). .The ANALOG CHANNEL OPERATIONAL TEST would be followed by-the ASME operability test at the minimum pressure required to-overcome the PORV(s) spring pressure (325-400 psig). Based ^ on'a review of the literature on cold overpressure events, most of the past low temperature overpressure -(LTOP) events were attributable to one of 

               'the following initiators:

Freauency

1. Charging / Letdown Mismatch 0.035/yr
2. Spurious SI Actuation 0.016
3. RHR Isolation 0.004 i
4. RCP Initiation 0.035 i The first category, charging / letdown flow mismatch, consists of those events
               -in which a flow imbalance exists between the letdown flow via the RHR and the CVCS charging.-flow. This event results in a not mass increase into the RCS and a corresponding pressure increase. A flow imbalance could be created'by a decrease in the letdown flow (closure of the CVCS letdown pressure control valve) or an increase in the charging flow due to operator or instrument error.         This type of event is not considered -to be a significant hazard during    y the proposed' testing interval since the RCS pressure will be monitored to maintain the pressure below the Technical Specification pressure limit for the Egiven-temperature. . If.a charging / letdown flow mismatch occurs it would be terminated by' operator action, actuation _ of the - RdR discharge relief- valve (s),

actuation of the administratively declared inoperable PORV(s), or actuation of 

               ?theLOPERABLE PORV before reaching-the'STPECS. administrative limits on RCS                 L pressure.

L The second event category, spurious SI initiation results in a sudden increase in'the mass input into.the RCS and a corresponding sudden' pressure rise. This event is prevented by the implementation of administrative _ controls during the PORV: testing to' allow only one centrifuga1' charging pump-(CCP) to be operable Eto minimize the. potential for mass input overpressure _ transients. In Laddition, .the High Head Safety Injection System (HHSI) pumps will be inoperable during water solid operations with one or both COMS PORVs L inoperable'. In accordance with STPECS_ Technical Specification LCO 3.5.3.2, all JWSI pumps are to be inoperable in MODES 5 & 6 with the. head on the reactor vessel. As stated-in this LCO, the HHSI pumps may be energized for-testing'or for fillingLthe accumulators in MODES 5 &-6 with the head:on the reactor vessel only if the pump discharge is isolated from the RCS by a closed L isolation valve _with the power removed from the valve operator or by a manual l isolation valve secured in position. In addition 1the these requirements, administrative controls will be provided to prevent operation of the HHSI pumps during the PORV test. These requirements minimize the potential for creating a mee. input overpressure transient. 

 -               A1/036 N19
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_ _ . - .._ - . _ . . . = __ B Attachmenc 1 ST-HL AE 3642 Page 9 of 11 The third event category, RHR isolation results in a sudden loss of letdown with continuation of charging flow which creates a mass input transient. The probability of a sudden loss of letdown is minimized since the RHR auto closure interlock is bypassed [or deleted) during this test. This type of event would be terminated by the isolation of charging flow by the operator, by actuation of the RHR relief valve (s), actuation of the administrative 1y declared inoperable PORV(s), or by actuation of the OPERABLE PORV. The final event category, RCP initiation, creates a heat input transient because of the temperature difference between the RCS and the steam generator secondary side. This event is prevented by administrative controls which will not allow starting or restarting a Reactor Coolant Pump with the RCS water solid unless this action does not result in a heat input injection transient. These controls will minimize the potential for pressure transients resulting from RCP initiation. The following administrative controls and Technical Specification requirements assure that the potential for a low temperature overpressure event is minimized during plant heatup and PORV testing:

a. When RCS pressure is being maintained by the low pressure letdown control valve, the normal letdown orifices are bypassed but not isolated.
b. Only one centrifugal charging pump (CCP) will be allowed to be operable; this minimizes the potential for a mass input overpressure transient,
c. Administrative controls will be in place to insure that the High Heau Safety Injection (HHSI) pumps will not operate during water solid operations with the PORV(s) inoperable to minimize the potential for creating a cold overpressure transient,
d. The RPV pressure will be controlled at the minimum value necessary to perform the required testing of the inoperable PORV(s) (325-400 psig).
c. A Reactor Coolant Pump shall not be started with one or more of the RCS cold leg temperatures less that or equal to 350 F unless the secondary side water temperature of each steam generator is less than 50 F above the RCS cold leg tempetature (ref. Technical Specification 3.4.1.4.1.a),
f. The positi:: displacement pump will be demonstrated inoperable during the water solid operations to minimize the potential for a mass input overpressure event.

A1/038.N10 

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.f       e       - -,o  ,

s Attachment 1 ST-HL AE 3642 Page 10 of 11

g. The1RHR auto-closure interlock will be bypassed [or deleted) durin6 water solid operations to prevent-the loss of letdown capability which could produce a mass input overpressure transient.
                                ; h.    :The Pressurizer Heaters will be. inoperable during water solid
                                         -operations to minimize the potential for a heat input overpressure                    -{
                                       -transient.                                                                               i i

Based on the above administrative controls, the possibility of a cold overpressure event during testing of the inoperable PORV(s) is considered 

                                                   ~

remote.- ' Prompt operator action, actuation of-the RHR relief valve (s), actuation of-the PORV(s) being tested, or actuation-of the OPERABLE PORV will ensure that the ASME III, Appendix C limits are not-exceeded. / Therefore-the-intent of,the current Technical Specification is. addressed cthrough an engineering evaluation which demonstrates that. adequate precautions or messures'that minimize the severity of, or the potential for, a cold overpressure' transient-are maintained during the operability test. HL&P

believes that eliminating-the requirement to maintain the RCS-depressurized does.not involve:a significant hazards consideration and results-in more reliable and safer operations.
 ?
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i I A1/036 N19 

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Attachment 1 ST-HL AE 3642 Page 11 of 11

REFERENCES:

1. STPEGS LER 90 008, dated June 4,1990
2. Generic Letter 90-06, " RESOLUTION OF GENERIC ISSUE 70, " POWER-OPERATED RELIEF VALVE AND BLOCK VALVE . RELIABILITY," AND GENERIC ISSUE 94, " ADDITIONAL LOW-TEMPERATURE OVERPRESSURE PROTECTION FOR LIGHT- WATER REACTORS," PURSUANT TO 10 CFR 50.54(f)", Dated June 25, 1990, i

l l l l A1/030.N10}}

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