ML20086P211

Proposed Tech Spec 4.5.2.h Re ECCS

ML20086P211
Person / Time
Site:	Callaway
Issue date:	12/18/1991
From:	UNION ELECTRIC CO.
To:
Shared Package
ML20086P210	List: ML20086P207 ML20086P211
References
NUDOCS 9112260259
Download: ML20086P211 (13)

Text

. .

Attachment 1 ULilRC-2535 Marked-un Technical 'pocification Pace.g Pago 3/4 5-6 Insert A Page B 3/4 5-2 Insert B (2 of 2) .

-9112260259 91121e

PDR ADOCK 05000483 P PDR

REVISlay y CHERGENCY CORE C00llNG SYST[MS .

SURVLILLANCl REQUIREMENTS (Continued) ,

By performing a flow balance test, during shutdown, following ompletion of modifications to the ECCS. subsystems that alter th su stem flow characteristics and verifying that:

For c rifugal charging pump lines, with a sin pump running:

Myt,g g 1)

1. N 2 a) The sum the injection line flow es, excluding the highest flo te, is greater t or equal to 346 gpm, and b) The total pump flow less than or equal to 550 ppm. .

2) For Safety injec pump lines, wit single pump running:

a) The of the injection line flow rate excluding the est flow rate, is greater than or equa 462 gpm, and b) Tne total pump flow rate is less than or equal to 655 g ,

j -4. By performing a flow test, during shutdown, following completion of modifications to the RHR subsystems that alter the subsystem flow

)

characteristics and verifying that for RHR pump lines, with a single pump running: )

~

1) The sum of the injection line flow rates is greater than or equal to 3800 gpm, and

2) The total pump flow rate is less than or equal to 5500 gpm.

,,).,

f CALLAWAY - UNll 1 3/4 5-6

. TH5dnT* & 0 66 l of l

h. By performing a flow balance test of the affected centrifugal charging pump portions of the ECCS subsystem, during shutdown, following completion of modifications to that contrifugal charging pump subsystem that alters the subsystem flow characteristics. The test shall be performed with a single pump running and the throttle valves set within setting tolerance to provide balanced branch line flow. Under these conditions there is zero mini-flow and 79 plus 2 or minus 4 gpm simulated reactor coolant pump seal injection line flow. This test shall verify:

1) the total flow to the four branch lines is less than or equal to 469 gpm, and

2) the total flow to the four branch lines is greater than or equal to 406.2 gpm (This corresponds to an analyzed flow rate of 301.8 gpm through the three lowest flow branch lines).

i. By performing a flow balance test of the affected safety injection pump portions of the ECCS subsystem, during shutdown, following completion of modifications to that safety injection pump subsystem that alters the subsystem flow characteristics. The test shall be performed with a single pump running and the throttle valves set within setting tolerance to provide balanced branch line flow. This test shall verify:

1) the total pump flow rate is less than or equal to 675 gpm, and

2) the total flow to the four branch lines is greater than or equal to 611.3 gpm (This corresponds to an analyzed flow rate of 455.6 gpm through the three lowest flow branch lines).

l

i EMERGENCY CORE COOLING SYSTEMS BASES ECCS SUBSYSTEMS (Continued)

The limitation for a maximum of one centrifugal charging pump to be I OPERABLE and the Surveillance Requirement to verify all charging pumps except the required OPERABLE charging pump to be inoperable in MODES 4 and 5 and in i

MODE 6 with the reactor vessel head on, provides assurance that a mass addi-tion pressure transient can be relieved by the operation of a single POR1 or RHR suction relief valve. In addition, the requirement to verify all Safety Injection pumps to be inoperable in MODE 4 in MODE 5 with the water level above the top of the reactor vessel flange, and in MODE 6 with the reactor i vessel head on and with the water level above the top of the reactor vessel flange, provides assurance that the mass addition can be relieved by a single

. PORY or RHR suction relief valve.

With the water level not above the top of the reactor vessel flange and With the vessel head on Safety Injection pumps may be available to mitigate the effects of a loss of decay heat removil during pertially drained conditions.

Ibn Survallhee "cNiremera provided " enwe OPERA &ftiTV vf eath compqnent ensure, t .a a minimum, the a um tions used in the safety ana ses are m t and that bsyst OPERABILITY < maint ned. Surveillance Requ ments g for th ttle va e position stops and ow balan testing provide ass ance

-J that pr er E S flows will e main ined in the e ent of a LOCA. M ntenance of prope f w resistance an pr .ure drop in the iping system t each injec-tion poin is necessary to: , prevent total pump low from ex eding runout conditio ben the system i 1 its minimum resistan e confi ation,(2) provid the _ oper flow s tb ween injection points in ac rdance with the assum tions us in the CCS-LOC analyses, and (3) pro d an acceptable level

.n/re;er offiol CCC fiq pell injection poi 1nts entrel te er et ue that-esn cd jn

@ th ECCS LOCA cna mes.M The Surveillance Requirements for leakage testing of ECCS check valves ensure that a failure of one valve will not cause an inter-system LOCA. The Surveillance Requirement to vent the ECCS pump casings and accessible, i.e., can be reached without personnel hazard or high radiation dose, discharge piping ensures against inoperable pumps caused by gas binding or water hammer in ECCS piping.

3/4.5.5 REFUELING WATER STORAGE TANK The OPERABILITY of the refueling water storage tank (RWST) as part of the ECCS ensures that a sufficient supply of borated water is available for injec-tion by the ECCS in the event of a LOCA. The limits on RWST minimum volume and boron concentration ensure that: (1) sufficient water is available within containment to permit recirculation cooling flow to the core, and (2) the reactor will remain subcritical in the cold condition followin; mixing of the RWST and the RCS water volumes assuming all the control rods are out of the core. These assumptions are consistent with the LOCA analyses.

1 CALLAWAY - UNIT 1 B 3/4 5-2 Amendment No. /,2, 44

.TAlJca.r & l'%d I o F 2. l The Surveillance Requirements, which are provided to ensure the OPERABILITY of each component, ensure that, at a l minimum, the assumptions used in the safety analyses are met  !

and that subsystem OPERADILITY is maintained. The safety analyses make assumptions with respect to: (1) both the maximum and minimum total cystem resistance, (2) both the maximum and minimum branch injection line resistance, and (3) the maximum and minimum ranges of potential pump performance. These resistances and ranges of pump performance are used to calculate the maximum and minimum ECCS flows assumed in the safety analyses, j The contrifugal charging pump minimum flow Surveillance Requirement provides the absolute minimum injected flow  !

assumed in the safety analyses. The maximum total system resistance defines the range of minimum flows (including the minimum flow Surveillance Requirement), with respect to pump head, that is assumed in the safety analyses. Therefore, the centrifuggi charging pump total system reaistance ,

((P -P must not be greater than 1.004E-02 ft/gpm',

wheNe pCS)s/Q i hum)pdischargepressureinfeet, P 8 pressurNinfeet, and Qd is the total pump flo0CEate in gpm.

The safety injection pump minimum flow Surveillance Requirement provides the absolute minimum injected flow assumed in the safety analyses. The maximum total system resistance defines the range of minimum flows (including the minimum flow Surveillance Requirement), with respect to pump head, that is assumed in the safety analyses. Therefore, the safety injection pump total system resistance

((P -P gCS)/Q *) must not be greater than 0.423E-02 ft/gpm2 ,

wheNe ishumpdischargepressurei- feet, P is RCS 1

pressurNinfeet, and Od is the total pump flo6CEate in gpm.

The centrifugal charging pump maximum total pump flow Surveillance Requirement ensures the maximum injection flow limit of 550 gpm is not exceeded. This value of flow is comprised of the total flow to the four branch lines of 469 gpm and a seal injection flow of 79 gpm plus 2 gpm for instr'ement uncertainties.

The safety injection pump maximum total pump flow surveillance Requirement ensures the maximum injection ficw limit of 675 gpm is not exceeded. This value of flow includes a nominal 30 gpm of mini-flow.

The test procedure places requirements on instrument accuracy (20 inches of water column for the charging branch lines and 10 inches of water column for the safety injection branct lines) and setting tolerance (30 inches of water I

column for both the charging and safety injection branch lines) such that branch line flow imbalance remains within the assumptions of the safety analyses.

f

.2W~< h #

/4s 2. o f 2, The maximum and minimum potential pump performance curves, in conjunction with the maximum and minimum flow surveillance Requirements, the maximum total system -

resistance, and the test procedure requirements, ensure that the assumptions of the safety analyses remain valid.

The surveillance flow and differential pressure requirements are the Safety Analysis Limits and do not include instrument uncertainties. These instrument uncertainties will be accounted for in the surveillance test procedure to assure that the Safety Analysis Linits are met.

l l

I

Attachment 2 Page 1 of 5 ,

U111RC- 2 5 3 5 l

SAFETY EVALUATIDH Backaround The ECCS serves to provide core cooling in respo.e- to a design ,

-basis accident. The system consists of two trai.3 of three pumps l with each train capable of injecting to the core from the i setpoint of the Pressurizer Safety Valves down to ambient  :

pressure conditions. Both trains start automatically upon receipt of a safety Injection Signal (SIS). One to three pumps inject depending on Reactor Coolant System (RCS) pressure, with  ;

all three pumps injecting at ambient RCS pressure. Tha function

'of the_ECCS pumps, along with the associated valves and piping, includes providing core cooling to ensure that the Peak Cladding Temperature (PCT) of the fuel does not exceed 2,200'F. The i Centrifugal Charging Pumps (CCPs) and Safety Injection Pumps

~

(SIPS) are an integral-part of the ECCS system.

Throttle valves and flow restricting orifices are installed in the ECCS branch injection legs. These flow restricting devices induce a backpressure on the ECCS pumps to ensure that pump

~ runout does not exist in the event of ambient RCS pressure. The throttle valves are adjusted to provide balanced branch line flows and ensure adequate bac.: pressure for the high head (CC) and intermediate head (SI) pumps. These throttle valves are adjusted during the Technical Specification required flow balance test.

This amendment request is Jubmitted to address Westinghouse Potential. Issues (PIs) which may impact the Callaway ECCS. The PIs which have been evaluated and addressed in support of this amendment request are discussed herein.

Potential Issues for ECCS flow imbalance and RCP seal injection were both considered in the analysis which was performed to

-support this amendment request. The PI which addresses ECCS flow measurement uncertainties was considered when calculating branch .

line imbalance. The header flow uncertainties will be accounted I for in the-flow balance procedure. The PI which discusses pump runout maximum safeguards flow rate no longer applies to Callaway since *.he analysis which supports this amendment request uses the same niaximum runout flow rate as the callaway LOCA analysis. The PI which discusses SCCS pump runout issues was addressed during

-the CCP flow test, as discustied below.

The evaluatione associated w.th these PIs indicate that the CCPs '

and SIPS.may develop greater flow at pump runout conditions than was previously considered in the Callaway accident analysis.

This condition could cause & Technical Specification compliance situation during Callaway Retuel 5 due to a potential inability to meet Technical Specificati on 4.5.2.h. Union Electric may be required to perform an ECCS f.ow balance test during Refuel 5, as required by Technical Specifiestion 4.5.2.h.

t Attachment 2 Page 2 of 5 U LNRC- 2 5 3 5 Proposed Chance This amendment application requests a revision to Technical 4 Specification 4.5.2.h to change the total pump flow for the CCPs to a value that is greater than or equal to 406.2 gpm but less than or equal to 469 gpm and the SIPS to a value greater than or equal to 611.3 gpm but'less than or equal to 675 gpm. This amendment also revises the requirements for performing a flow br. lance test on an ECCS subsystem and provides additional infornation on system conditions needed to assure the flow balance test is valid. This ECCS LCO ensures that total pump flow will not exceed runout conditions and proper flow exists in each ECCS subsystem. The Bases 3/4.5.2, 3/4.5.3, and 3/4.5.4 discussion on Subsystem OPERABILITY is revised to describe the limits and conditions for CCP and SIP operation.

The second portion of this amendment application provides clarification of when flow balance testing of the ECCS subsystem is required. The CCPs and SI pumps inject to the cold legs of the reactor coolant system (RCS) through two separate flow paths. The CCPs inject through the Boron Injection Tank and the SI pumps inject through the accumulator injection piping.

Therefore, there is no need to perform a flow balance test to both subsystems since any modification to one injection flow path will not affect the system characteristics of the ether flow ,

path.

The proposed change to Bases 3/4.5.2, 3/4.5.3, and 3/4.5.4 provides information concerning the ECCS pump flow limits. This information is provided for completeness.

Safety Analysis

A review of Callaway FSAR Chapter 15 indicated .that the accident analysis'would not be adversely impacted by this change. This conclusion is based on a review of the accidents which are  :

impacted-by ECCS fitas; Low Temperature Overpressure Protection System (LTOPS) analysis, Steam Generator Tube Rupture (SGTR)

Margin to Overfill, Containment Integrity analysis, Loss of Coolant Acc.' dents (LOCAs), Main Steamline and Main Feedline Breaks.

The LTOPS-analysis assumes that 1 PORV or RHR suction relief valve has adequate capacity to relieve the mass input from the operation of a single charging pump at maximum flow with inadvertent isolation of letdown flow. Inadvertent actuation of a safety injection pump was not explicitly analyzed since its operation is prevented by the Technical Specifications. A review of this analysis confirmed that adequate relief capacity exists for both the-PORVs and RHR suction relief valves for a CCP flow of 550 gpm.

l V .. -- -

Attachment 2 Page 3 of 5 ULNRC- 2 5 35

'All tho-SGTR analyses _ assume injection of the Sips and CCPs if the RCS pressure drops below their shutoff head. Review of these cases showed little potential for additional injected flow, assuming grcator SIP unout flow. No reanalysis is required since a forced overfill case was analyzed (see ULNRC-1518) in response to an NRC question. To force overfill, many assumptions af the original ovt 11.11 analyses were conrervatively altered, includin!j adding 165 - > the charging pump f3aw rate. This change is more than sufficient to offset any additional injected flow due to the increased. SIP runout flow. Since this forced overfill analysis resulted in an offsite dose less than that of the case presented in the Callaway FSAR, the impact of increased SIP runout flow will not increase offsite dose in excess of that previously analyzed.

The Containment' Integrity analysis is not affected because the small amount of mass addition is insignificant when compared to the total ECCS pump flows.

The increase in the maximum ECCS flowrate is_due to the potential for lower system friction resistance. The lower system friction resistance could-result in increased spilled flow and decreased delivered core ' low for large or small break LOCAs. In addition, exceeding this requiremrat could result in a higher pump runout which could result in damage to a pump and a loss of safety

. injection function. To address this concern, a model of the ECCS was-constructed using the Westinghouse computer code PEGISYS.

This code uses piping data and component specifications to calculate flow rates throughout a piping network. The model was constructed according to Callaway Piping and Instrumentation

-Diagrams and the vendor _ pump curves for the CCPs.and SIPS. This model has shown that CCP and SI pump _ flows allowed by this change produce acceptable LOCA~ flows. Therefore, there is no impact on large cr small break LCCA because of this change, and no PCT penalty is assessed against the LOCA analyses.

Main steamline breaks were reviewed as a result of the changes in ECCS flow. Mass and energy-releases both inside and outside

-containment'were evaluated as well as_the core response to a hypothetical main steamline break. The results and conclusions of the FSAR remain valid for the revised allowed flow rates. In addition, the main feedwater line break was also reviewed. The results and conclusions of the FSAR remain valid.

The CVCS Malfunction Analysis is not affected because the change in system characteristics is insignificant when compared to the original Callaway analysis.

Based on evaluations performed for the revised ECCS flows, the results and conclusions of the FSAR safety analysis remain valid.

l i

l

Attachment 2 Page 4 of 5 ULNRC- 2 5 3 5 Pumo Performance An evaluation of the Westinghouse PIs was performed for Callaway Plant. The evaluation determined that both the CCPs and SI pumps could produce flowrates greater than originally calculated.

However, the evaluation also determined that the pumps had been tested to the higher capacities, the pumps have adequate not positive suction head (NPSH) for the higher capacities and the ECCS system piping and valves are capable of functioning with the increased flow.

The Westinghouse model predicted that the CCP and SIP could experience a 17 anu 16 gpm boost, respectively, in flow when aligned in the recirculation phase of ECCS operation. This portion of the model was performed as a best estimate of the maximum flowrates during any phase of ECCS operation. Based upon 5

the limit of 550 gpm for the CCP and 675 gpm for the SIP as discussed in this submittal, the tota. flowrate expected for the pumps then becomes 567 gpm for the CCP and 691 gpm for the SIP.

Union Electric, with the assistance of Pacific / Dresser Pump, conducted a performance test of a replacement CCP to determine hydraulic characteristics at higher flowrates. The pump was operated at 574 gpm to ensure pump integrity would not be compromised at the higher recirculation flows. At this flowrate the CCP required a net positive suction head (NPSH) of 43 feet of water. The current performance curve for the SIP provides a data point at 695 gpm on the NPSH curve that demonstrates that 17 feet of water is required to support this flowrate. Additionally, the SIPS have delivered 706 gpm under field conditions and shown no signs of degradation. The RHR pumps supply suction pressure to the CCP and SIP when in the recirculation phase of ECCS -

operation. Even when considering that the RHR pump is operating at a maximum runout flow, a minimum of 275 feet of water is available, which is well above that required to support operation of the CCP and SIP.

Based upon the above, the ECCS has the hydraulic capacity necessary to support the flowrates that are predicted to be occurring during any phase of operation.

Evaluatics The proposed change to Technical Specification 4.5.2.h does not involve an unreviewed Safety question because operation of Callaway plant with this change would not:

P

1. Increase the probability of occurrence or the consequences of an accident or malfunction of equipment important to safety previously evaluated in the safety analysis report.

There is no increase in the probability of occurrence or the consequences of an accident. The design of the ECCS piping, valves, and pumps has been reviewed and found adequate to

~

Attachment 2 Page 5 of-5 ULNRC- 2 5 3 5 support opera tion with increased flow. -The Callaway Safety Analysis has-been evaluated based on the proposed changes to the7 ECCS flow criteria. The consequences of-any accident or malfunction of equipment has not increased. Performing a flow balance test on just the affected ECCS subsystem has no effect on any accident as the intent of the Technical Specifications is being met.

2. Create a possibility for an accident or malfunction of a different type than any~previously evaluated in the safety analysis report. There-is no new type of accident or malfunction created and the method and manner of plant operation remains unchanged.

3. Reduce the margin of safety as defined in the basis for any technical-specification. This is based on the fact that no plant design' changes are involved and the current practicac and procedures for operating the ECCS system will not change.

Given the above discussions as well as those presented in the Significant Hazards Evaluation,-the proposed change does not adversely affect or endanger the health or safety of the general public or involve a significant safety hazard.

l l

- . - . - -- . - . ~ . .- , .-_

Attachment 3 Page 1 of 1 1 ULNRC- 2 53 5 SIGNIFICANT HAZARDS EVALUATION This amendment application requests a revision to Technical Specification 4.5.2.h to revise the total pump flow for the CCPs and SI Pumps, to modify the requirements for performing a flow

-balance test on an ECCS subsystem, and to add additional information into the Bases.

A review of the CCP and SIP hydraulic requirements and the Callaway Safety Analysis indicates that the CCPs and SIPS are capable of operation at 550 and 675 gpm, respectively, with no effect on pump operability.or plant safety.

The proposed change does not involve a significant hazards consideration because operation of Callaway Plant with this change _would not:

1. _ Involve a significant' increase in the probability or consequences-of an accident previously evaluated. The callaway' Safety Analysis has been reviewed and been found to be unaffected by.this proposed change. The design of the ECCS piping, valves, and pumps has been reviewed and found adequate to support operation with increased flow. The callaway Safety Analysis has been evaluated based on the proposed changes to the ECCS flow criteria. The consequences of any accident or malfunction of equipment has not increased. Performing a flow balance test on just the affected ECCS Subsystem has no effect on any accident as the intent of the Technical Specifications is being met.

-2. Create the possibility of a new or different kind of accident from_any previously evaluated. There is no new type of accident or malfunction created and the method and manner of plant-operation remains unchanged.

3. Involve.a significant reduction in a margin of safety. The margin of safety remains unaffected since no design change is_made and ECCS operation remains the same.

As discussed above, the proposed change does not involvo a significant increase in the probability or consequences of an accident previously evaluated or create the possibility of a new or different-kind of accident from any previously evaluated. This change does not result in a significant reduction in a margin of safety. Therefore, it has been determined that the proposed change does not involve a significant hazards consideration.

Attachment 4 Page 1 of 1 U LNRC-2 5 3 5 ENVIRONI'tENTAL CONSIDERATION This amendment application requests a revision to Technical Specification 4.5.2.h to revise the total pump floM for the CCPs and SI Pumps, to modify the requirements for performing a flow balance test on an ECCS subsystem,. and to add additional information into the Bases.

A review of the CCP and SIP hydraulic requirements and the Callaway Safety Analysis indicates that the CCPs and SIPS are capable of operation at 550 and 675 gpm, respectively, with no effect on pump operability or plant safety.

The proposed amendment involves changes with respect to the use of facility components located within the restricted area as defined in 10 CFR Part 20, and changes a surveillance requirement. Union Electric has determined that the proposed amendment involves no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite and that there is no significant increase in individual or cumulative occupational radiation exposure.

Accordingly, the proposed amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22 (c)(9). Pursuant to 10 CFR 51.22 (b) no environmental impact statement or environmental assessment need be prepared in connection with the issuance of this amendment.