ML20215N786

Proposed Tech Specs Re Standby Liquid Control Sys

ML20215N786
Person / Time
Site:	Quad Cities
Issue date:	10/28/1986
From:	COMMONWEALTH EDISON CO.
To:
Shared Package
ML20215N780	List: ML20215N779 ML20215N786
References
NUDOCS 8611070271
Download: ML20215N786 (8)

Text

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QUAD-CITIES DPR-30

, 3.4/4.4 STANDBY LIQUID CONTROL SYSTEM LIMITING CONDITIONS FOR OPERATION SURVEILLANCE REQUIREMENTS Applicability: Applicability:

Applies to the operating status of the Applies to the periodic testing require-ctendby liquid control system. monts for the standby liquid control system.

Objective: Objective:

To assure the availability of an indepen- To verify the operability of the standby

'dtnt reactivity control mechanism. liquid control system.

SPECIFICATIONS A. Normal Operation A. Normal Operation During periods when fuel is in the The operability of the standby liquid reactor and prior to startup from a control system shall be verified by cold condition, the standby liquid performance of the following tests:

control system shall be operable except as specified in Specification 1. At least once per month 3.4.B. This system need not be oper-able when the reactor is in the cold Demineralized water shall be shutdown condition, all contro1~ rods recycled to the test tank. Pump are fully inserted, and Specification minimum flow rate of 40 spm l 3.3.A is met. shall be verified against a

system head of 1275 psig.

2. At least once during each opera-ting cycle Manually initiate the system, except the explosion valves and pump solution in the recircula-tion path to demonstrate that the pump s ction line from the storage taak is not plugged.

Explode two of six charges or two of four charges manufactured in the same batch using the per-manent system wiring to verify proper function. Then instal?,

the untested charges in the 8611070271 861028 explosion valves.

PDR ADOCK 05000265 P PDR Domineralized water shall be injected via a test connection into the reactor vessel to test

,that valves (except explosion valves) not checked by the recirculation test are not clogged.

0624H 3.4/4.4-1 Amendment No.

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QUAD-CITIES DPR-30 Test that the setting of the system pressure relief valves is between 1455 and 1545 psig.

3. Disassemble and inspect one explosion valve so that it can be established that the valve is not clogged. Both valves shall be inspected in the course of two operating cycles.

B. Operation with Inoperable Conditions B. Operation with Inoperable Components From and after the date that.a redun- When a component becomes inoperable, i its redundant component shall be dant component is made or found to be inoperable, Specification 3.4.A shall demonstrated to be operable immedi-

be considered fulfilled and continued ately and daily thereafter.

operation permitted provided that the

component is returned to an operable condition within 7 days.

C. . Liquid Poison Tank-Boron Concentration C. Liquid Poison Tank-Boron Concentration The liquid poison tank shall contain The availability of the proper a boron-bearing solution of at least boron-bearing solution shall be veri-3321 gallons of at least 14 WT fled by performance of the following

. percent sodium pentaborate tests:

Decahydrate (Na2 B10 016 -

10H2 0) at all times when the 1. At least once per month standby liquid control system is

, required to.be operable and the Boron concentration shall be solution temperature shall not be determined. In addition, the less than the temperature presented boron concentration shall be in Figure 3.4-2. determined any time water or boron are added or if the D. If Specifications 3.4.A through C are solution temperature drops below not met, an. orderly shutdown shall be the limits specified by Figure initiated and the reactor shall be in 3.4-2.

the cold shutdown condition within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. 2. At least one per day Solution volume shall be checked.

j' 3. At least once per day The solution temperature shall be checked.

t 0624H 3.4/4.4-2 Amendment No.

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QUAD-CITIES OPR-29 3.4 LIMITING CONDITIONS FOR OPERATION BASES A. The design objective of the standby liquid control system is to provide the capability of bringing the reactor from full power to a cold, xenon-free shutdown assuming that none of the withdrawn control rods can be inserted. To meet'this objective, the liquid control system is designed to inject a quantity of boron which produces a concentration of no less than 600 ppm of boron in the reactor core in approximately 83 minutes with imperfect. mixing. A boron concentration of.600 ppm in the reactor core is required to bring the reactor from full power to 3%

ak or more subcritical condition considering the hot to cold reactivity swing, xenon poisoning and an additional margin in the reactor core for imperfect mixing of the chemical solution in the reactor water. A normal quantity of 3,321 gallons of solution.having a 14% sodium pentaborate concentration is required to meet this shutdown requirement.

For a required pumping rate of 40 gpm, 3321 gallons of at least 14 WT  !

percent solution will be inserted in approximately 83 minutes. This insertion rate of boron solution will override the rate of reactivity insertion due to cool down of the reactor following the zenon peak.

Two pump operation will enable faster reactor shutdown for ATHS events. The monthly pump minimum flowrate test shall require a minimum flowrate of 40 gpm. This requirement, combined with the solution concentration requirement of at least 14 WT percent, will demonstrate that the Standby Liquid Control System meets the requirements of 10CFR50.62.

Boron concentration, solution temperature,,-and volume are checked on a frequency to assure a high reliability of operation of the system should it ever be required. Experience with pump operability indicates that monthly testing is adequate to detect if failures have occurred.

The only practical time to test the standby liquid control system is during a refueling outage and by initiation from local stations.

Components of the system are checked periodically as described above and make a functional test of the entire system on a frequency of less tha.n once each refueling outage unnecessary. A test of explosive charges from one manufacturing batch is made to assure that the charges are satisfactory. A continual check of the firing circuit continuity is provided by pliot lights in the control room.

B. Only one of two standby liquid control pumping circuits is needed for proper operation of the system. If one pumping circuit is found to be inoperable, there is no immediate threat to shutdown capability, and reactor operation may continue while repairs are being made. Assurance that the remaining system will perform its intended function and that the reliability of the system is good is obtained by demonstrating operation of the pump in the operable circuit at least once daily. A reliability analysis indicates that the plant can be operated safely in this manner for 7 days.

0624H 3.4/4.4-3 Amendment No.

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QUAD-CITIES DPR-30 C. The solution saturation temperature of 13% sodium pentaborate, by weight, is 59 0F. The solution shall be kept at least 10 F 0above the saturation temperature to guard against boron precipitation. The 100 F margin'is included in Figure 3.3-1. Temperature and liquid level alarms for the system are annuciated in the control room.

Pump operability is checked on a frequency to assure a high reliability ,

of operation of the system should it ever be required.

Once the solution has been made up, boron concentration will not vary unless more boron or more water is added. Level indication and alarm indicate Whether the solution volume has changed, vhich might indicate a possible solution concentration change. Considering these factors, the test interval has been established.

D. periodic tests to demonstrate two-pump flow capability are not feasible in the present system configuration and are unnecessary because the flow path integrity can be determined from the test of a single pump.

Comparison of single-pump test pressures with previous results and correlation of these data with initial two-pump tests are used to verify the capability of the piping.

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l 0624H 3.4/4.4-3a Amendment No.

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QUAD-CITIES DPR-30

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E VOLUME CONCENTRATION REQUIREMENT 13 -

3470 gal em 16 3000 3500 4000 4500 5000 5500 VOLUME OF SOLUTION (gal)

FIGURE 3.4-1 STANOBY LIQUID CONTROL SOLUTION REQUIREMENTS

. AMENDMENT NO.

DPR-30

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• ATTACIGENT 2 NO SIGNIFICANT HAZARDS CONSIDERATION EVALUATION

! DESCRIPTION OF PROPOSED CHANGE c--nwealth Edison '(Ceco) proposes to modify the Quad Cities Unit 2 Technical Specifications to support a planned modification to the Standby Liquid control System (SBLC) to meet the requirements of 10 CPR 50.62. The specific changes to the' Technical Specifications involve replacing the boron concentration versus solution volume curve (Figure 3.4-1) with a minimum allowable volume of 3321 gallons of solution at a minimum concentration of 14 weight percent. The required SBLC pump flow rate is increased from 39 to 40 gpm. Also the allowable setpoint band for the system pressure relief valves has been increased from the current 1400 to 1490 psig to a band of

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1455 to 1545 psig to reflect the increased pump discharge pressure during

two pump operation. Finally, the Technical Specification bases have been revised to reflect the above changes.

DISCUSSION 10 CFR 50.62(c)(4) requires a SBLC system with a minimum flow capacity and boron content equivalent to 86 gpm of 13 weight percent sodium pentaborate solution. For Quad Cities Unit 2, this is being accomplished by modifying the SBLC system to allow dual pump operation (80 gym combined flow rate) and revising the_ Technical Specifications to require a 14% minimum concentration. The minimum required volume of solution in the Technical Specifications is revised from the previous 3,470 gallons of 13.4% solution I (from Figure 3.4-1) to 3,321 gallons of 14% solution. This preserves the original amount of boron injection.

As a result of two pump SBLC system operation discharge pressures will be higher. Accordingly, the allowable system pressure relief valve setpoints have been increased by approximately 55 psig.

BASIS FOR NO SIGNIFICANT HAZARDS CONSIDERATION commonwealth Edison has evaluated the proposed Technical Specification changes and determined they do not represent a significant hazards consideration. Based on the criteria for defining a significant hazards consideration established in 10 CFR 50.92(c), operation of Quad Cities in accordance with the proposed amendment will not:

1. Involve a significant increase in the probability or_ consequences of an accident previously evaluated because the proposed changes maintain the total amount of boron injection previously required by the Technical Specifications thereby maintaining the previous shutdown reactivity capability. The proposed changes are needed to implement the requirements of 10 CFR 50.62 and have no impact on systems or equipment that could potentially initiate or impact the probability of an accident.

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2. Create the possibility of a new or different kind of accident from any accident previously evaluated because the changes involve a system whose

-only function is to provide a backup shutdown capability. The changes do not affect any systems or equipment which could initiate an accident.

3. Involve a significant reduction in the margin of safety because the overall shutdown reactivity capability (i.e. total boron injection) of the SBLC system is not reduced by these changes. The proposed amendment supports required modifications which will increase the SBLC system injection rate, thereby increasing the margin of safety for Anticipated Transient without Scram events.

Based on the above discussion, commonwealth Edison concludes the proposed Technical Specification changes do not represent a Significant Hazards Consideration.

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