ML20215K240

Proposed Tech Specs,Clarifying RCS Boron Dilution Requirements

ML20215K240
Person / Time
Site:	Beaver Valley
Issue date:	04/30/1987
From:	DUQUESNE LIGHT CO.
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ML20215K224	List: ML20215K222 ML20215K226 ML20215K240
References
NUDOCS 8705110126
Download: ML20215K240 (9)

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ATTACHMENT A

i Revise the Technical Specifications as follows:

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REACTIVITY CONTROL SYSTEMS BORON DILUTION i

LIMITING CONDITION FOR OPERATION l

3.1.1.3 The flow rate of reactor coolant through the core shall be 1

3000 gpm whenever a

reduction

• in Reactor Coolant System boron l

i concentration is being made.

APPLICABILITY:

All MODES.

ACTION:

With the flow rate of reactor coolant through the core < 3000 gpm, immediately suspend all operations involving a reduction

• in boron l

concentration of the Reactor Coolant System.

SURVEILLANCE REQUIREMENTS l

1 4.1.1.3 The flow rate of reactor coolant through the core shall be determined to be 1 3000 gpm prior to the start of and at least once per hour during a

reduction

• in the Reactor Coolant System boron l

concentration by either:

a.

Verifying at least one reactor coolant pump is in operation, or b.

Verifying that at least one RHR pump is in operation and supplying 1 3000 gpm through the core.

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Reduction involves the addition of water to the RCS with a boron concentration less than that RCS boron concentration required to 1

satisfy the minimum shutdown margin.

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i BEAVER VALLEY - UNIT 1 3/4 1-4

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PROPOSED WORDING i

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REACTOR COOLANT SYSTEM ISOLATED LOOP i

LIMITING CONDITION FOR OPERATION 3.4.1.4 The boron concentration of an isolated loop shall be greater than or equal to the boron concentration required in accordance with Technical Specifications 3.1.1.2 and 3.9.1 as applicable to satisfy the minimum shutdown boron concentration of the RCS and unisolated loop (s) prior to opening the isolated loop (s) stop valves.

APPLICABILITY MODES 5 and 6.

ACTION:

J With the requirements of the above specification not satisfied, do 1

not open the isolated loop's stop valves.

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l SURVEILLANCE REQUIREMENTS i,

4.4.1.4 The boron concentration of an isolated loop shall be determined to be greater than or equal to the baron concentration required to satisfy the minimum shutdown boron concentration of the RCS and unisolated loop (s) within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> and again within 30 minutes prior to opening either the hot leg or cold leg stop valves of an isolated loop.

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DEAVER VALLEY - UNIT 1 3/4 4-3 PROPOSED WORDING s

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3/4.4 REACTOR COOLANT SYSTEM BASES

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3/4.4.1 REACTOR COOLANT LOOPS, (continued) of Appendix G

by either (1) restricting the water level in the pressurizer and thereby providing a volume for the primary coolant to expand into or (2) by restricting starting of the RCPs to when the secondary water temperature of each steam generator is less than 25"F above each of the RCS cold leg temperatures.

The requirement to maintain the boron concentration of an isolated loop greater than or equal to the boron concentration required to satisfy the applicable minimum shutdown boron concentration of the RCS and unisolated loop (s) prior to opening the loop stop valves ensures that no reactivity addition to the core could occur during startup of an isolated loop.

Verification of the boron concentration in an idle loop immediately prior to opening the stop valves provides a

reassurance of the adequacy of the boron concentration in the isolated loop.

Operating the isolated loop on recirculating flow for at least 90 minutes prior to opening its stop valves ensures adequate mixing of the coolant in this loop and prevents any reactivity effects due to boron concentration stratifications.

Startup of an idle loop will inject cool water from the loop into the core.

The reactivity transient resulting from this cool water injection is minimized by delaying isolated loop startup until its temperature is within 20*F of the operating loops.

Making the reactor subcritical prior to loop startup prevents any power spike which could result from this cool water induced reactivity transient.

3/4.4.2 and 3/4.4.3 SAFETY VALVES The pressurizer code safety valves operate to prevent the RCS from being pressurized above a

Safety Limit of 2735 psig.

Each safety valve is designed to relieve 345,000 lbs. per hour of saturated steam at the valve set point.

The relief capacity of a single safety valve is adequate to BEAVER VALLEY - UNIT 1 B 3/4 4-la PROPOSED WORDING

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REFUELING OPERATION 3/4.9.8 RESIDUAL HEAT REMOVAL AND COOLANT CIRCULATION LIMITING CONDITION FOR OPERATION 3.9.8.1 At least one residual heat removal (RHR) loop shall be in operation.

APPLICABILITY:

MODE 6 ACTION a.

With less than one residual heat removal loop in operation, except as provided in b below, suspend all operations involving in increase in the reactor decay heat load or a reduction in boron concentration of the Reactor Coolant System.

Close all containment penetrations providing direct access from the containment atmosphere to the outside atmosphere within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.

b.

The residual heat removal loop may be removed from operation for up to 1

hour per 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> period during the performance of CORE ALTERATIONS in the vicinity of the reactor pressure vessel (hot)

legs, c.

The residual heat removal loop may be removed from operation for up to 4

hours per 8

hour period during the performance of Ultrasonic In-service Inspection inside the reactor vessel nozzles provided there is at least 23 feet of water above the top of the reactor vessel flange.

d.

The provisions of Specification 3.0.3 are not applicable.

SURVEILLANCE REQUIREMENTS 4.9.8.1 At least one residual heat removal loop shall be verified to be in operation and circulating reactor coolant at a flow rate of 1

3000 gpm at least once por 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> when making boron dilution

• l changes and 1 1000 gpm for decay heat removal when the Reactor Coolant System is in the drained down condition within the loops.

Dilution involves the addition of water to the RCS with a baron concentration less than that RCS boron concentration required to satisfy the minimum shutdown margin.

BEAVER VALLEY - UNIT 1 3/4 9-8 PROPOSED WORDING

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ATTACHMENT B

Proposed Technical Specification Change No. 131 No Significant Hazard Consideration Description of amendment request:

The proposed amendment would revise applicable specifications to clarify RCS dilution requirements.

1.

Page 3/4 1-4, Section 3.1.1.3 Boron Dilution has been revised by applicable to the word reduction in the LCO, adding a

note Action statement and surveillance requirement.

A reduction in RCS boron concentration is described as the addition of water to the RCS containing a boron concentration that is less than that RCS boron concentration required to satisfy the minimum shutdown margin.

2.

Page 3/4 4-3, Section 3.4.1.4 Isolated Loop has been revised so that the isolated loop boron concentration must be greater than or equal to that required prior to opening the isolated loops stop valves.

The applicability statement has been revised from Modes 1, 2, 3, 4 and 5 to apply in Modes 5 and 6 only.

The plant is not permitted to operate with one loop isolated in Modes 1-4 in accordance with License Condition 2.C(3).

A specification to address plant operation in Modes 1-4 will be required only for N-1 loop operation, therefore, the N-1 technical specification change submittal will include a specification applicable in Modes l

l-4.

This reflects the NRC SER for N-1 loop operation which requires the plant to be in at least Mode 5 prior to unisolating a

loop.

The action statement has been revised to reflect the change in applicability.

Surveillance requirement 4.4.1.4 has been revised to clarify the minimum shutdown boron concentration and by replacing the phrase at least once per 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> and with within 4

hours and

again, this will remove the requirement to sample the isolated loops every 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> when the plant is shutdown since the plant may be in this condition for an extended period of time.

Sampling this often would remove a large volume of water from the loop and it is physically very difficult to add makeup water to the isolated loop.

The additional requirement to sample within 4

hours and again within 30 minutes prior to opening the loop stop valves will ensure at least two samples are taken for redundant verification of isolated loop boron concentration.

3.

Page 3/4 9-8, Section 3.9.8 Residual Heat Removal and Coolant Circulation has been revised by adding a note

• applicable to the word dilution in the surveillance requirement.

An RCS boron dilution is described as the addition of water to the RCS containing a boron concentration that is less than that RCS boron concentration required to satisfy the minimum shutdown margin.

4.

Bases Section 3/4.4.1 Reactor Coolant Loops has been revised to reflect the change to section 3.4.1.4 concerning isolated loop startup requirements.

ATTACHMENT B (cont.)

Pcg3 2 Basis for no significant hazards determination:

The proposed changes do not involve a significant hazards consideration because operation of the plant in accordance with these changes would not:

1)

Involve a

significant increase in the probability of occurrence or the consequence of an accident or malfunction of equipment important to safety previously evaluated because:

A.

Section 3.1.1.3:

Clarification of boron reduction is required to alleviate delays associated with returning an isolated loop to service.

Delays have been encountered during RHR

tests, RHR startup and in returning an isolated loop to service.

The RCS baron concentration was high and in accordance with technical specifications the isolated loop could not be returned to servico until the boron concentration of the isolated loop was at a concentration greater than or equal to that of the RCS.

Therefore, in order to satisfy the technical specification requirements, the RCS baron concentration had to be reduced to loss than that of the isolated loop.

The proposed change would climinato future problems of this type by clarification of reduction, such

that, RCS boron concentration reduction would be interpreted to be involved only if the baron concentration of the water being added to the RCS is less than that concentration required to satisfy the minimum shutdown margin.

The minimum shutdown margin is required to ensure:

1) the reactor can be made subcritical from all operating conditions, 2) the reactivity transients associated with postulated accident conditions are controllable within acceptable limits, and 3) the reactor will be maintained sufficiently subcritical to preclude inadvertent criticality in the shutdown condition.

This proposed change is consistent with and continues to satisfy the shutdown margin requirements assumed in the accident analysis.

Thorofore, this change will not affect the probability of occurrence or the consequence of an accident previously evaluated.

B.

Section 3.4.1.4:

This chango providos additional clarification of the isolated loop boron concentration requirements and is consistent with the previous discussion.

The Applicability and Action statements have been revised to apply to Modos 5 and 6.

This is consistent with the NRC SER on N-1 loop operation and since the plant must be in at least Mode 5

to unisolate a loop, applicability in Modos 1 through 4 is not required.

Section 4.4.1.4 has been revised to remove the requirement to sample the isolated loops ovary 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> when the plant is shutdown sinco the plant may bo in this condition for an extended period of time.

Sampling this often would remove a

largo votame of water from the loop and it is physically very difficult to add makeup water to the isolated loop without exceeding differential pressure limitations on the steam generators.

The additional requirement to sample within 4

hours and-again within 30 minutes prior to opening the loop stop valves will ensure at least two samples are taken for redundant verification of the isolated loop baron concontration.

T

' ATTACHMENT B Pcga 3 C.

Section 3.9.8.1:

This change provides additional clarification of dilution for addition of water to the RCS and is consistent with the previous discussion for boron reduction.

D.

Pasos Section 3/4.4.1:

The bases have boon revised to clarify the isolated loop startup requirements.

In accordance with UFSAR Section 7.6.2 Reactor Coolant System Loop Isolation Valve Interlocks and UFSAR Section 14.1.6 Startup of an Inactive Reactor Coolant

Loop, the RCS loop stop valve interlocks are provided to ensure that an accidental startup of an isolated loop which has a lower temperature or lower baron concentration than the core and active loops will be a relatively slow event.

The interlocks insure that flow from the isolated loop to the remainder of the RCS takes place through the relief line bypassing the cold leg stop valve for a

period of approximately one hour before the cold leg stop valvo can be opened.

The flow through the relief line is made low (no more than 300 gpm) so that the temperature and baron concentration in the isolated loop are brought to equilibrium with the remainder of the system at a relatively slow rato should the administrative procedurcs be violated and an attempt made to open the stop valves when the isolated loop temperatures or boron concentration is lower than that in the core and the active loops.

The proposed changos do not affect the RCS loop isolation valvo interlocks.

In

additien, technical specification 3.4.1.5 Isolated Loop

Startup, requires thats a) the isolated loop is recirculated for at least 90 minutos at 125 gpm and the

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temperature the isolated loop cold log is within 20*F of the highest cold log temperature of the operating loops and b) the reactor is subcritical at least 1%

AK/K.

Temperature and coolant circulation requirements are then available to preclude a positive reactivity addition due to startup of an isolated loop.

Therefore, these changes will not affect the probability of occurrence or the consequences of an accident previously evaluated.

2)

Create the possibility of a

now or different kind of accident from any accident previously evaluated because:

The proposed change will clarify the meaning of diluting the RCS.

A reduction in boron concentration or dilution would be indicated, by definition, only if the water to be added to the RCS contained baron at a

concentration less than that required to satisfy the minimum shutdown margin.

Since the accident analysis is based on a

minimum shutdown margin being availabic and those changes are consistent with that requirement, the safe operation of the plant will not be affected.

Thorofore, those changes will not create the possibility of a now or different kind of accident from those described in the UFSAR.

r ATTACHMENT B Pcg3 4 3)

Involve a

significant reduction in the margin of safety because:

Shutdown margin requirements vary throughout core life as a function of fuel depletion, RCS boron concentration, and RCS Tavg.

Since shutdown margin is a standard method for calculating core reactivity the addition of borated water to the RCS can be determined and based on shutdown margin without introducing any new or different calculations into the operating requirements.

Therefore, these changes do not significantly affect the bases for any technical specification, do not affect the safe operation of the plant and are consistent with the Boration Control bases concerning minimum shutdown margin.

Conclusion The proposed changes do not involvo a significant increase in the probability or consequences of a previously evaluated accident, do not create the possibility of a new or different kind of accident and do not involve a

significant reduction in a margin of safety.

A reduction in RCS boron concentration or an RCS dilution would be described only if the water to be added to the RCS contained boron at a

concentration less than that required to satisfy the minimum shutdown margin.

The accident analysis is based on the availability of a

minimum shutdown margin and the proposed changes are consistent with that requiremont, thorofore, the proposed changes will not affect the safe operation of the plant.

Boron dilution accidents are analyzed in UFSAR Section 14.1.4 Uncontrolled Boron Dilution and the potential affects of opening loop stop valvos is described in UFSAR Section 14.1.6 startup of an Inactivo reactor Coolant Loop.

Thorofore, based on the above, it is proposed to characterize the change as involving no significant hazards consideration.

a