ML20085G155

Rev 1 to Proposed Amend to License NPF-29 (PCOL-91/03), Deleting Surveillance Requirements in TS Table 4.3.1.1-1 to Perform Average power-range Monitor Flow Biased Simulated Thermal power-high Functional Unit

ML20085G155
Person / Time
Site:	Grand Gulf
Issue date:	10/18/1991
From:	Cottle W ENTERGY OPERATIONS, INC.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20085G158	List: ML20085G155 ML20085G159
References
GNRO-91-00176, GNRO-91-176, NUDOCS 9110240165
Download: ML20085G155 (11)

Text

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W. T. Cottio

. , n F l October 18. 1991 '

U.S. Nuc1 car Rngulatory Commission Mail Station P1-137 Washington, D.C. 20555 Attention: Document Control Desk

SUBJECT:

Grand Gulf Nuclear Stacion Unit 1 Docket No. 50-416 License No. NPF-29 Reactor Protection System Instrumentation Surveillance Requirements (Table 4.3.1.1-1)

Proposed Amendment to thn Operating License (PCOL-91/03, Revision 1)

GNRO-91/00176 Gentlemen:

Futergy Operations, Inc. submitted by letter dated April 26, 1991, a pwposed ameadment to the Grand Gulf Nuclear Station (UGNS) Operating

, hiconso. The proposed GGNS Technical Specif.ication (TS) amendment would have deleted the requirement to perform Note (h) daily for the Average Power Range Monitor Flow Piased Simulated Thermal Power-liigh Tunctional Unit identified as Item 2.b in TS Table 4.3.1.1-1.

By letten dated July 10, 1991, t.hn NRC denici this proposnd amendment.

AddJtional information supporting thn proposort change was provided to the NRC in letter dated August 15, 1991. After further discussion with the NRC staff, Entergy Operations is resubmitting thin proposnd amendment which combines the initial proponal and the additional information. No technical changes have been made to the information previously submitted; therefore, the determine tion of no significant hazards considerations remains valid.

In accordr.nce with the provisions of 10CFR50.4, the signed original of the requested amendment is enclosed. At.tachmnnts 2 and 3 provide the cochnical justification and discussion to support the requested nmendment.

G9110162/SNI,1CFLR - 1 l g 9110240165 911018 PDR ADOCK 05000416 P FLA

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October:18. 1991

-GNRO-91/00176 Page 2 of 3 This amendment request has been reviewed and accepted by the Plant Safety Review Committee. 1hc Safety Review Lammittee reviewed and approved the initial application.

- Yours truly, M 7"""* C M  :

WTC/SBM/ams.

attachments: 1. Affirmation per 10CFR50.30

2. GGNS PCOL-91/03

3. Loss of Feedwater lleating (LFWil) Analyses cc: Mr. D. C. Ilintz (w/a)

Mr. J. Mathis (w/a)

Mr. R. B. McGehee (w/a).

Mr. N. S. Reynolds (w/a)

Mr. II. L. Thomas (w/c)

Mr. Slowart D. Ebnnter (w/a)

Regional Administrator-U.S. Nuclear Regulatory Cormission Region II 101 Marietta St., N.W., Suite 2900 .

Atlanta, Georgia 30323 Mr. P. W. O'Connor, Project Mannger (w/a)

Office of Nuclear Reactor Regulation U.S.1 Nuclear Rehulatory Commission Mail Stop 13113 Washington, D.C. 20555 Dr. Alton B. Cobb (w/a)

State lloalth Officer State Board of Ilealth P.O. Box 1700

. Jackson, Mississippi 39?05 G9110162/SNLICFI.R - 2

~

, BEFORE Tile UNITED STATES NUCLEAR REGULATORY COMMISSION LICENSE NO. NPF-29 DOCKET NO. 50-416 IN Tile MATTER OF MISSISSTPPI POWER & LIGilT COMPANY and SYSTEM ENERGY RESOURCES, INC.

and SOUTil MISSISSIPPI ELECTRIC POWER ASSOCI ATION and l'URGY OPERATIONS. INC.

AFFIPMATION I.-W. T. Cottle, being duly sworn, state that I am f/ ice President, Operations GGNS cf'Entergy Operations, Inc.; that on behalf of Entergy

-Operations, Inc., System Energy Resources, Inc., and South Mississippi Electric Power Association I am authorized by Entergy Operations, Inc. to sign and file with the Nucinar Regulatory Commission, this application for amendment of.the Operating License of tl.a Orand Gulf Nuclear Station; that I signed this application as Vice President, Operations GGNS of-Entergy Operations, Inc. ; and that tl:s statements made and the matters set forth therein are true and. correct to the best of my knowledge, information and belief.

wrW W. T. Cottle STATE OF MISSISSIPPI COUNTY OF CLAIBORNE SUBSCRIBED AND SWORN TO before me, a Notary Public, in and for the County and State above named, this G day of Gdch1M , 1991.

(SEAL)

%dsYL DkWh ch Notary @ lic}

My commission expires:

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Attachment 2 to GNRO-91/00176 Page 1 of 7

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e A. SUBJECT

1. NL-91/03 Deletion of Daily Requirement to Perform Note (h) for-the APRM Flow Blased Simulated Thermal Power-liigh Functional Unit 2.- Affected Technical ~ Specification:

Table 4.3.1.1-1, " Reactor Protection System Instrumentation Surveillance Requirements", Item 2.b and Note (h) pages 3/4 >

3-7 and 3/4 3-8 B.- DISCUSSION-

1. This proposed change to the GGNS Technical Specifications (TS)

-would delete the requirement to perform Note (h) daily for the Average- Power Range Monitor ( APRM) Flow Biased Simulated Thermal Power-liigh scram function identified as item 2.b in Table 4.3.1.1-1.

2.- The daily surveillance provides information and protection

-redundant to other surveillance-requirements. GGNS identified the deletion of this surveillance as a TS change beneficial to safety through reduction of operator burden. While the proposed change, in and of.itself, may not provide a major reduction in operator -burden, we believe that the cumulative effect of this and similar changes planned for.the future will be a positive safety improvement. i

3. Through our_ evaluation of the historical basis for the Daily

-Channel Check requirement, we have found that the note was incorporated into the draft BWR-6 Standard Technical Specification (STS) (the last official version of the BWR STS s for the BWR-5 does not contain the foctnote at all) with the following' wording:

" Verify measuredLcore flow to be greater than.or equal to established core flow at the existing flow control valve position."

4. The wording of the note varies from plant _to plant. A review of selected samples of different plant TS has shown how the _

original intent of the note has been obscured an each of these plants have negotiated their own wording. We believe that the differences in the wording are due to each plant's attempt to

, rationalize the note or to minimize its effect having determined-that the note does not reflect a serious concern or has no basis for being~1n the Reactor Protection System (RPS) instrumentation TS.

5. GGNS proposes'the following TS changes:

-a. Delete the daily surveillance specified in Table 4.3.1.1-1 for item 2.b, " Average Power Range Monitor Flow Biased Simulated Thermal Power-liigh."

-09110162/SNLICFLR - 6

Attachment 2 to GNRO-91/00176 Page 2 of 7 i

b. Delets the Note (h) in Table 4.3.1.1-1 associated with the daily surveillance which is also being deleted.

Marked up TS pages reflecting the propcsod TS changes described above are included.

6. The proposed changes and basis are similar to those granted by the NRC for Fermi-2 in Amendment No. 19 and Clinton Power Station in Amendment No. 30.

C. JUSTIFICATION

1. The APRM Flow-Blased Simuloted Thermal Power (APRM-FBSTP) scram function monitors parameters to approximate che thermal power being transferred to the reactor coolant. The APRM neutron flux is electronically filtered with a time constant representative of the inel heat transfer dynamics to generate a signal proportional to the thermal power in the reactor. The trip setpoint is varied as a function of recirculation drive flow (i.e., at lower core flows, the setpoint is reduced proportional tc the reduction in power experienced as core flow is reduced with a fixed control rod pattern) but is clamped at an upper limit. The APRM-FBSTP scram function can provide an added level of protaction against-transients where thermal power increases slowly. During these type of events, the thermal power increase does not significantly lag the neutron flux response and, because of a lower trip setpoint, the APRM-FBSTP function can initiate a scram before the high neutron flux scram. For rapid neutron flux increase events, the thermal power lags the neutron flux and the APRM Neutron Flex - liigh scram function provides a scram signal before the APRM-FBSTP scram function setpoint is exceeded.

2. The GGNS reload safety analysis does tiot take credit for the APRM-FBSTP scram function in ensuring the safety limit minimum critical power ratio is not exceeded. An evaluation of the historien1 significance of the APRM-FBSTP scram function with regard to each GGNS reload safety analysis !s included in Attachment 3. The evaluation demonstrates that any incraase in the simulated thermal power scram setpoint is well analyzed for the loss of feedwater heating ("nnt (i.e. , no scram is assumed).

3. The daily surveillance performed to safisty Note (h) is somewhat in disagreement with the jetpump surveillance contained in TS 4.4.1.2.1.a. The Note (h) surveillance requires the measured drive flow to be less than or equal to the established drive flow while the jetpump surveillance requires the measured drive flow to be within 10% of the established. Thus, in order to ensure compliance to Note (h), the jetpump surveillance is forced to be less than or equal to minus 10% of the establi=hed as the instrumentation is the same. This requiremnnt places undue restrictions on the jetpump surveillance. In addition, at measured drive flows greater than approximately 69%, the G9110162/SNLICFLR - 7

Attachment 2 to GNRO-91/00176 Page 3 of 7 APRM-FBSTP scram function is clamped; therefore, the surveillance provides no useful indication except at reduced flows.

4. A' review of the various versions of the note shows that, with minor variations, there are two general versions, neither of which exactly matches the wording appearing in the draf t BWR-6 STS:

(a) One version of the note requires verifying that indicated or measured reactor recirculation loop drive flow for a given flow control valvo position is less than or equal to a previoualy established reactor recirculation loop drive flow for that flow control valve position. (This is the version that appears in the GGNS and River Bend TS.)

(b) The other version requires verifying that measured total core flow (total jet pump flow) for a given indicated reactor recirculation loop drive flow (as sensed by the APRMs) is greater than or equal to a previously established tctal core flow for that particular reactor recirculation loop drive flow. (This is the version that appears in the Perry TS and was in the Clinton TS as well as the Nine Mile Point TS except that the latter replaces the " greater than or equal to" with the words "in the range of." LaSalle has a similar note, i.e., the words " greater than or equal to" are not included.)

5. Based on our-evaluation, we believe that the following concerns and/or ever.ts may have been considered when the note was incorporated in the TS:

(a) Flow control valve crudding; (b) Jet pump beam cracking; (c) Jet pump blockage; (d) Core crudding; and (e) Jet pump instrumentation problems.

An evaluation of these concerns is discussed as follows:

Flow Control _ Valve _(FCV) Cruddina - Crudding of thn flow control valve would result in a trend where recirculation loop drive flew would decrease over time for a given FCV position. Because core flow would also decrease (the core-flow / drive-flow relationship is roughly proportional except at low flow conditions where natural circulation dominates), this situation would not result in a non-conservative condition with raspect to the APRM-FBSTP scram function.

Version (a) of the note addresses the drive-flow /FCV-position relationship, but, for the reason discussed above, should not be associated with APRM-FbSTP TS since it would be of limited value from that standpoint. (A check performed in accordance with Version (a) will l

G9110162/SNLICPLR - 8

i 1

• Attachment!2:to GNRO-91/00176 :

Page 4 of 7 l always be satisfied because the tbove-noted trend ensures

-it. The requirement for ensuring that the APRM-FBSTP

' instrumentation is sensing the' correct drive flow is . fully met by-performing the required Channel Check, Channel Functional Test and Channel Calibration requirements for this instrumentation.) Version (b) is not applicable to thsl drive-flow /FCV-position relationship since -it only considers changes in the core-flow / drive-flow relationship.

A check of the drive-flow /FCV-position relationship is only appropriate for TS 3/4.4.1.2 (Jet Pump Operability) where a number of daily surveillances are required for the reactor recirculation system. These surveillances are lirted

.belowi

-(a) Verify the indicated recirculation loop flow does not differ by more than 10% from the established FCV-position-loop flow characteristics.

(b) Verify the indicated total core flow does not differ by more than 10% from the established total core flow value derived from recirculation loop flow measurements.

(c) Verify the indicated dif fuser-to-lower plenum differential pressure of any individual jet pump does not dif fer from established patterns by. more than 10%.

It should be noted that relationships addressed by either version of the note are both addressed in these su cve ill ances . Changes in the drive-flow /FCV-position relationship would be revealed by performance of item (a) above.-

, -Jet Pump _ Beam _ Cracking - This phenomenon was addressed in

.GE Service Information Letter (SIL) Nc. 330. GGNS has

. evaluated the SIL and a discunnion of the GGNS response is found in Supplement 6 to the GGNS Safety Evaluation LReport (NUREG-0831). The individual ' jet pump dif fuser-to-lower-plenum differential pressure check, as required per GGNS TS-4.4.1.2.1.c (i.e., the. third item on the list presented previously), was identified in the Slb as an acceptable method for identifying this. phenomenon. If this event was to occur, this daily surveillance check would recognize it.

Failure to meet the acceptance criteria would then require a' plant shutdown because the corresponding ACTION under TS 3.4.1.2 states, "With one or more jet pumps inoperable,- be in at least IIOT SilUTDOWN within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />." Additional-ACTION-under the RPS instrumentation TS is redundant and unnecessary.

G9110162/SNLICFLR - 9

Attachment 2 to-GNRO-91/00176 Page 5 of 7 Jet Pump _ Blockage - In the unlikely event a jet pump becomes blocked or obstructed, the daily jet pump performance surveillances discussed above would reveal this condition as well.

Core Crudding - Th1 change in m-ratio (recirculation loop flow minus recirculation loop drive flow divided by recirculation loop drive flow); 1.e., core flow / drive flow relationship that might occur from beginning-of-cycle to end-of-cycle due to core crudding; is so slight that this phenomenon is not a significant concern. The resultant change in the m-ratio would have negligible impact on the APRM-FDSTP trip setpoint. A core flow calibration is performed at least once per cycle using Reactor Engineering procedures to ensure that accuracy is being maintained in the core flow and recirculation flow measurement systems.

The recirculation flow units and APRM flow hiased scram circuitry is checked periodically per required surveillances. These activities ensure that W (percent of rated recirculation drive flow) as required for RPS e-

-instrumentation is accurate. A significant change in core flow or drive flow is more likely to be the result of the phenomena [(b) and (c)] discussed'previously.

Jet pump Instrumentation Problems - A jet pump

-instrumentation problem in always a possibility; and, if any of the surveillances under TS 3/4.4.1.2 yicided unacceptable results, a jet pump instrumentation problem would be suspected. Cross checks against other related

' instruments associated with the required jet pump would be '

performed to determine-if it is indeed just an instrument

-problem. If an instrument problem is identified, then necessary actions would be performed to restore the instrumentation to operable status. No concern with respect to the APRM-FBSTP trip exists-(assuming the J APRM-FDSTP instrumentation' is operable as verified by the performance of its associated surveillances) because=the jet pump instrument problem does not involve an actual changc~in jet pump flow.

In summary, the above five concerna are adequately addressed by-the RPS instrumentation surveillances, the daily jet pump surveillances:and the cycle core-flow calibration. Jet pump beam cracking or jet pump blockage which could cause a gross change in core flow and recirculation-flow relationships are adequately addressed

.by specific surveillance requirements. Changes to the core flow due to core crudding would be expected to be minimal over the course of the cycle.- The core flow calibration at least once per cycle and the surveillance requirements for RPS and jet pump instrumentation provide assurance that the concerns associated with core crudding are adequately

'G9110162/SNLICFLR - 10

At.tachment 2 to GNRO-91/00176 pago 6 of 7 nddressed. On the cthor hand, the multiple burdons placed upon operators in the control room are a continuous concern, particularly unnecessary requirements which serve no sr.fety function. The daily performance of Noto (h),

therefore, should not be included in the RPS instrumentat.fon TS.

D. NO SIGNIFICANT llAZARDS CONSIDERATIONS

1. Entergy Operations, luc. is proposing that the TS Surveillanco Requirement of Tabic 4.3.1.1-1 to parform Note (h) daily for the Average Power Range Monitor Flow Diased Simulated Thormal Power-liigh scram function bo deleted. Adoquate stepn are taken without the Survol11ance Roquirement and Noto (h) to detect and take appropriato action for degradation in the amount of corn flow resulting from a given recirculation loop flow.

2. The Commission has provided standards for determining whether a no significant hnzards consideration exists as stated in 10CFR50.92(c). A proposed amendment to an operating license involves no significant hazards if operation of the facility in accordance with the proposed amendment would not: (1) involvo a significant increaso fu the probability or consequences of an accident previously evaluated; or (2) create the pcssibility of a now or different kind of accident from any accident previously evaluatod; or (3) . involve a significant reduction in a margin of safety.

3. GGNS has evaluated the no significant hazards considerations in its request for a license amendment., in accordanco with 10CFR50.91(a), GGNS is providing the following analysis of the proposed amendment against the three standards in 10CFR50.92:

a. No significant increnso in the probability or consequences of an accident previously evaluated results from this chango The proposed change to the GGNS TS does not involve an increaso in the probability or consequences of an accident previously evaluated because the proposed change only removes a requirement determined to be redundant to existing requirements and has no meaningful value from a safety point of view. With operablo RPS instrument.ation and periodic core flow calibrations, the accuracy of the APRM-FBSTP t.rlp is assured. Deviations or trends away f rom established core-floe and drivo-flow conditions will continue-to be indicatnd by performar.co ot the surveillances required uder TS 3/4.4.1.2. in addition, the proposed change is expected to result. In an unquantifiable decrease in the probability of previously evaluated accidents through the resulting reduction in control room operator burden.

G9110162/SNLICFLR - 11

Attachment 2 to GNRO-91/00176 Page 7 of 7 a

b. This change would not create the possibility of a new or different kind of accident from any previously analyzed.

The proposed chango does not create the possibility of a .

new or different kind of accident from any previously evaluated becauso no new modes of operation or changes to plant design are involved. Thn scope of the proposed chants is strictly limited to the deletion of tha daily survoillance requirement specified by Noto (h) which has been determined to involve no significant change to the protection afforded by existing surveillances,

c. This change would not involve a significant reduction in the margin of safety.

The proposed change docs not involve a reduction in a margin of safety because t.he rotationships (under TS 3.2.2) used to establir,h the APR!f Flow-Blased Simulated Thermal Power-liigh scram and Flow-Biased Neutron Flux-Upscale control rod block trip setpoints will remain unchanged.

The APRM indicated recirculation loop drive flows will continue to be appropriately checked to ensure that their established relationship to total core flow is preset en or accounted for under other TS. All other OPERA 3ILITY and Siirveillanco Requirements associated with the affected instrumentation remain unchanged. It should also be noted that the current redundancy of surveillance requirements does not reflect a margin of safety but rather a situation which, if carried to extremos, would constitute a serious safoty concern.

4. Based on the above evaluation, Entergy Operations, Inc. has

( concluded that operation in accordance with the proposed amendment involves no significant hazards considerations.

G9110162/SNLICFLR - 12

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