ML19325D554

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Proposed Tech Specs,Clarifying RCS Boron Dilution Requirements
ML19325D554
Person / Time
Site: Beaver Valley
Issue date: 10/16/1989
From:
DUQUESNE LIGHT CO.
To:
Shared Package
ML19325D552 List:
References
NUDOCS 8910250026
Download: ML19325D554 (27)
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Text

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.  ? .- ATTACHMENT A L. . -

Revise-the BV-1 Technical Specifications as follows:  !

i Remove Pages Insert Paaes 3 3/4 1-4 3/4 1-4 l

3/4 4-2c 3/4 4-2c l L3/4 4-3 3/4 4-3  ;

.3/4 4-4 3/4'4-4 3/4 9-8 3/4 9-8 3 l

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1 E4910250026 891016 {C PDR ADOCK 05000334 ,-

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REACTIVITY CONTROL SYSTEMS

, BORON DILUTION [

r LIMITING CONDITION FOR OPERATION 3.1.1.3 LThe flow rate of reactor coolant through the core shall be 2 3000 gpm whenever a. reduction

concentration is being made.  ;

APPLICABILITY: All MODES.# -l ACTION:

With .the flow rate of reactor coolant through the core < 3000 gpm,  !

-immediately suspend all operations involving a reduction

concentration of the Reactor Coolant System. .

i SURVEILLANCE REQUIREMENTS .

4 .1.1. 3 - The flow rate of reacter coolant through the core shall be determined to be 2 3000 gpm prior to the start of and at least once ,

per hour during a reduction

concentration by either:

l

a. Verifying at least one reactor coolant pump is in operation, or  ;
b. Verifying that at least one RHR pump is in operation and b supplying 2 3000 gpm through the core.

L 5

r

  • For purposes of this specification, the addition of borated water to the RCS does not constitute a reduction in RCS boron .

concentration provided the boron concentration of the borated ,

water being added is greater than the minimum required to satisfy  !

the requirements of one of the following applicable specifications: 3.1.1.1 for Modes 1 3 2,3 and 4; or 3.1.1.2 for Mode 5; or 3.9.1 for Mode 6.

  1. With fuel in the vessel.

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

f' 8

^.

3 .

REAC, TOR COQLANT SYSTEM

. SHUTDOWN j LIMITING CONDITION FOR OPERATION I i

3.4.1.3 a. At least two of the coolant' loops listed below shall be. .

' OPERABLE:

t l '. Reactor. Coolant Loop- (A) and its associated steam generator and. reactor coolant pump, .

t

2. Reactor Coolant Loop (B) and'its associated steam i generator and reactor coolant pump,  ;
3. Reactor Coolant Loop (C) and its associated steam generator and reactor coolant pump, s
4. Residual Heat Removal Pump (A) and a' heat "

exchanger,**

1

5. Residual Heat Removal Pump (B) and a second heat exchanger.**
b. At least one of the above coolant loops shall be in '

operation.***

APPLICABILITY: Modes 4 AND 5 4' ACTION: '

u a. With less than the above required loops OPERABLE,  ;

L immediately initiate corrective action to return the required loops to OPERABLE status as soon as.possible; be in COLD SHUTDOWN within 20 hours2.314815e-4 days <br />0.00556 hours <br />3.306878e-5 weeks <br />7.61e-6 months <br />. 1 b.- With no coolant loop in operation, suspend all operation ,

involving a reduction in boron concentration of the Reactor .

Coolant system and immediately' initiate corrective action to '

return the required coolant loop to operation. Refer to Specification 3.4.1.6 for additional limitations.

p.

p ** The normal or emergency power source may be inoperable in MODE 5.

l L *** All reactor coolant pumps and Residual Heat Removal pumps may be de-energized for up to 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> provided: 1) no operations are permitted that would cause dilution of the reacter coolant system E boron concentration and 2) core outlet temperature is maintained -

at least 10*F below saturation temperature. For purposes of this -

L specification, the addition of borated water to the RCS does not constituto dilution of the RCS boron concentration provided the boron concentration of the borated water being added is greater than the minimum required to satisfy the requirements of L specification 3.1.1.1 for Mode 4; or 3.1.1.2 for Mode S.

L BEAVER VALLEY - UNIT 1 3/4 4-2C PROPOSED

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,_ * ' ' REACTOR COOLANT SYSTEM ,

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ISOLATED. LOOP Y: r

. LIMITING CONDITION FOR OPERATION ,

t J 3.4.1.4. The RCS isolated loop stop valves shall have power removed

- from the associated valve operators *.

H

. APPLICABILITY: l Whenever an RCS loop has been isolated, Modes 5 and 6f. l.

ACTION:  ;

With the requirements of the above specification not satisfied, i remove power from the isolated loop stop valve operators

  • within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />.  !,

SURVEILLP.NCE REQUIREMENTS e

4.4.1.4 Verify at least once per 7 days that power is removed from the RCS isolated loop stop valve operators *.

  1. With fuel in the vessel.

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

i-l REACTOR COOLANT SYSTEM JSOLATED LOOP STARTUP  ;

i LIMITING CONDITION FOR OPERATION 3.4.1.5 The'RCS cold leg stop valve shall remain closed until: .

E a. The isolated loop har been operating on a recirculation flow of 2 125 gpm for at least 90 minutes and the temperature at the cold leg of the isolated loop is within 20*F of the highest cold leg temperature of the operating loops.

b. The reactor.is subcritical by at lear.t 1 percent k/k.

, <. c. The isolated loop boron concentration is greater than or equal to minimum required to satisfy the ' applicable  ;

requirements of Specification 3.1.1.2 for Mode 5' or Specification 3.9.1 for Mode. 6.

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APPLICABILITY: Modes 5 and 6*.

ACTION:

With the requirements of the above specification not satisfied, suspend startup of the isolated loop.

SURVEILLANCE REQUIREMENTS 4.4.1.5.1 The isolated loop cold leg temperature shall be determined to be within 20*F of the highest cold leg temperature of the operating- loops within 30 minutes prior to opening the cold leg stop ~

valve.

'4.4.1.5.2 The reactor shall be determined to be subcritical by at least 1 percent k/k within 30 minutes prior to opening the cold leg ,

stop valve.

i 4.4.1.5.3 The isolated loop boron concentration shall be determined to be greater than or equal to the minimum required to satisfy the

- applicable requirements of Specification 3.1.1.2 for Mode 5 or

, Specification 3.9.1 for Mode 6 within 30 minutes prior to opening the hot leg stop valve and again within 30 minutes prior to opening the cold leg stop valve.

  • With fuel in the vessel.

'E BEAVER VALLEY - UNIT 1 3/4 4-4 PROPOSED WORDING

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REFUELING OPERATION 1374 9.8 RESIDUAL HEAT REMOVAL AND COOLANT CIRCULATION I 1

LIMITING CONDITION FOR OPERATION i 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 below, suspend all operations involving -

an increase in the reactor decay heat load or a reduction

  • l .

in boron concentration of the Reactor Coolant System.~ ,

Closes 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 i for up to 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> 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.  :

I

c. The- residual heat removal loop may be removed from operation for up- to 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> 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 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 i l

l 4.9.8.1 At least one residual heat removal loop shall be verified to l' be in operation and circulating reactor coolant at a flow rate of i

1. > 3000 gpm at least once per 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
l. changes and 2 1000 gpm for decay heat removal when the Reactor i L

I Coolant System is in the drained down condition within the loops.

  • For purposes of this specification, the addition of borated water H to the RCS does not constitute a reduction or dilution in RCS 1 boron concentration provided the boron concentration of the '

borated water being added is greater than the minimum required to satisfy the requirements of specification 3.9.1 for Mode 6.

i

  1. With fuel in the vessel.

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

{.

i 3/4.4 REACTOR COOLANT SYSTEM 9

, BASES

=

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.

Power is removed from the isolated loop stop valves (hot leg and cold leg) to ensure that no reactivity addition to the core can occur while the loop is isolated due to inadvertent opening of the isolated loop stop valves. Isolated loop startup is limited to Modes 5 and 6 in accordance with the NRC SER on N-1 loop operation. Verification of the isolated loop boron concentration prior to opening the isolated loop stop valves provides a reassurance of the adequacy of l the shutdown margin in the rem.ainder of the system. Restoration of 1 power to the hot leg stop valve allows opening this valve to complete the recirculation flowpath in conjunction with the relief line bypaseing the cold leg stop valve and ensures adequate mixing in the  !

isolated loop. This enables the temperature and boron concentration of the isolated loop to be brought to equilibrium with the remainder j of the system. Limiting the temperature differential between the i isolated loop and the remainder of the system prior to opening the i cold leg stop valve prevents any significant reactivity offects due to cool water addition to the core.  !

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

, the core. The reactivity transient resulting from this cool water ,

I injection is minimized by delaying isolated loop startup until its  !

temperature is within 20*F of the operating loops. Making the .

reactor suberitical prior to loop startup prevents any pcwer spike l which could result from this cool water induced reactivity transient, j 3/4.4.2 and 3/4.4.3 SAFETY VALVES 1 e The pressurizer code safety valves operate to prevent the RCS from being pressurized above its Safety Limit of 2735 psig. Each safety' valve is designed to relieve 345,000 lbs. per hour of l saturated steam at the valve set point. The relief capacity of a l single safety valve is adequate to l

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l BEAVER VALLEY - UNIT 1 B 3/4 4-la PROPOSED WORDING l

.- ATTACHMENT B

. Safety Analysis .

Beaver Valley Power Station, Unit No. 1  !

Proposed Technical Soecification Chanae No. 166 -

t Description of amendment request: The proposed amendment would incorporate the pertinent aspects of applicable D.C. Cook and Millstone 3 technical specifications for clarification of RCS boron i dilution requirements. The following changes have been incorporated:

i

'1. Page 3/4 1-4 Section 3.1.1.3 Boron Dilution, has been revised by [

adding a note

  • applicable to the word reduction in the LCo,

' Action Statement and Surveillance Requirements. 'This note reflects the convention provided for D.C. Cook specification 3.1.2.7 by reference to specific shutdown margin specifications.

This note proposes to clarify the meaning of a boron reduction; I such that, for purposes of this specification, water added to the RCS- will not constitute a reduction in RCS boron concentration.as long as the boron concentration of the water added-is greater ,

than that minimum boron concentration that would satisfy the mode dependent minimum shutdown margin requirements. The minimum ,

shutdown . margin required for modes 1, 2, 3 and 4 is 1.77%4 K/K.

per specification 3.1.1.1, for mode 5, it is 1.0% A K/K per specification 3.1.1.2 and for mode 6, it is either a Keff of 0.95 or less or a minimum boron concentration of 2000 ppm per-specification 3.9.1. In addition, a note # "With fuel in the vessel" has been added to the Applicability statement. This is L

similar to the note applied to the Applicability statement of L specification 3.4.1.5.

l L 2. Page 3/4 4-2c Section 3.4.1.3 Reactor Coolant System Shutdown, I has been revised to clarify the word " dilution" in the note ***.

i This clarification is similar to the note applied to the word I dilution in surveillance requirement 4.9.8.1. For purposes of l this specification, water added to the RCS will not constitute dilution of the' RCS boron concentration provided the boron concentration of the borated water being added is greater than the minimum required to satisfy the requirements of specification l 3.1.1.1 for Mode 4; or 3.1.1.2 for Mode 5. ,

3. Page 3/4 4-3 section 3.4.1.4 Isolated Loop, this specification has been revised to address minimum shutdown margin requirements .

for the isolated loop. This specification now incorporates the  !

intent of Millstone 3 specification 3.4.1.5 to address the isolated loop stop valves. The LCO requires removal of power from the associated valve operators to ensure the valves cannot be inadvertently opened to cause a boron dilution event. The NRC recommends this as a compensatory measure in lieu of verifying the boron concentration once per 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> for the isolated loop.

To allow startup of an isolated loop, a note

  • allows power to be restored to the valve operators if surveillance requirement 4.4.1.5.3 is satisfied. This surveillance requirement, applicable to specification 3.4.1.5 Isolated Loop Startup, requires verification of the isolated loop boron concentration

[';' ' s c Att:ch2Ont B (Cont'd)

L ,Page 2.

i within 30 minutes of the time the hot leg stop valvec are opened and again within 30 minutes of the time the cold leg stop valves  ;

are opened to ensure the minimum shutdown margin requirements are met. The Applicability Statement has also been changed to apply }

this specification when a loop has been isolated in mode 5 and 6 only. This places additional limitations on N-1 loop operation, which will allow isolated loop operation only in modes 5 and 6.

The Action Statement has been written for consistency with the LCO to require removal of power from the isolated valve operators  ;

if aus operator finds that power had been restored. The above note * ' applied to the LCO is also applied here for the same '

reason, to allow isolated loop startup. Surveillance requirement 4.4.1.4 has been written for consistency with the LCO to verify at least once per 7 days that power is removed from the isolated loops. stop valves. In addition, a note # "With fuel in the vessel" has been added'to the Applicability statement. This is similar to the note applied to the Applicability statement of

, specification 3.4.1.5.

3. Page 3/4 4-4 Section 3.4.1.5 Isolated Loop Startup, has been revised to reflect the requirements of Millstone 3 specification 3.4.1.6 to maintain the isolated loop cold leg stop valve closed until the valve interlock requirements have been met for-(a) temperature and flow, (b) the reactor is subcritical by at least i 1%' A K/K, and (c) the isolated loop boron concentration is greater than or equal to the minimum required by specification 3.1.1.2  ;

for Mode 5 or specification 1.9.1 for Mode 6. Thesa requirements I.

ensure no reactivity transient will occur when an isolated loop E is being returned to service. The Applicability Statement has been changed to apply the requirements of this specification during startup of an isolated loop only during shutdown conditions. This is consistent with the NRC SER on'N-1 operation which requires the plant to be shutdown to return an isolated loop to service. The Action Statement provides adequate L direction for the above LCo, therefore, no change is required.

l Surveillance requirement 4.4.1.5.1 requires verification of LCO l item a. differential temperature, this is consistent with the valve interlock requirements, therefore, no change is required.

Surveillance requirement 4.4.1.5.2 requires verification of LCO item b. 1% shutdown margin, this is consistent with the FSAR accident analyses, therefore, no change is required. Surveillance requirement 4.4.1.5.3 has been added to require verification of LCO item c. isolated loop boron concentration within 30 minutes before the hot leg stop valve may be opened and again within 30 l minutes before the cold leg stop valve is opened. This will L ensure the 1% shutdown margin is maintained in accordance with l the accident analysis. Therefore, all of the prerequisites are l consolidated into one specification and are verified prior to l

returning an isolated loop to service.

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, AttcchnOnt B (C:nt'd)  !

Page 3  !
5. Page 3/4 9-8 Section 3.9.8.1 Residual Heat Removal and Coolant
  • Circulation, has been - revised by adding a note
  • similar to the note applied to section 3.1.1.3. This note has been applied to the word dilution in surveillance requirement 4.9.8.1 and also to i the word reduction in Action a. For purposes of this specification, water added to the RCS will not constitute a-reduction or dilution in boron concentration as long as the boron ,

concentration of the water being added is greater than that minimum boron concentration required to satisfy the minimum requirements of specification 3.9.1 for mode 6. In addition, a note. -# "With fuel in the vessel" has been added to- the Applicability statement. This is similar to the note applied to the Applicability statement of specification 3.4.1.5.

6. Page B3/4 4-la bases Section 3/4.4.1 Reactor Coolant Loops, has been revised to reflect the changes to Sections 3.4.1.4 and 3.4.1.5. Power is removed from the isolated loop stop valves in accordance with 3.4.1.4 to ensure the valves will not be inadvertently opened. Opening the valves could cause a reactivity transient resulting from cool water injection or by adding water with a low boron concentration. The boron concentration, temperature differential and shutdown margin are verified in accordance with 3.4.1.5 before an isolated loop can be returned to service to minimize the reactivity effects due to ,

this transient.

The technical- specification requirements that will be in effect to preclude a reactivity transient during isolated loop startup can

'be. summarized as follows:

1. Power is removed from the isolated loop stop valve operators and is verified periodically. This ensures the valves cannot be inadvertently opened. (Specification 3.4.1.4)
2. Power can be restored to the hot leg isolated loop stop valve operator following verification of adequate shutdown margin in the isolated loop. (* note applied to valve operators in ,

specification 3.4.1.4.)

l 3. The hot leg isolated loop stop valve can then be opened to l complete the recirculation flowpath for the 2" relief line flow which bypasses the cold leg stop valve. (Surveillance requirement 4.4.1.5.3.)

l 4. Recirculation flow is provided for at least 90 minutes to achieve L adequate mixing in the isolated loop and enable the temperature i and boron concentration of the isolated loop to be brought to l equilibrium with the remainder of the system at a relatively slow L rate. (Specification 3.4.1.5.a) l 1

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L k a .,, 1 Atticchm:nt B (C:nt'd) 4 Sa( ,Page 4 '

5. Power can be restored to the cold leg isolated loop stop valve operator following verification of:
a. Adoquate shutdown margin in the isolated loop, and (Surveillance requirement 4.4.1.5.3) 1 L
b. The reactor is subcritical by at least 1% 6 K/K, and ,

(Surveillance requirement 4.4.1.5.2) -

c. The isolated loop cold leg temperature is within 20'F of the highest cold leg temperature of the operating loops.

(Surveillance requirement 4.4.1.5.1) t

6. The cold leg isolation valvo can then be opened to return the loop to operable status. (Surveillance requirement 4.4.1.5.3)

Along with the technical specification requirements, interlocks i .that are a part of the Reactor Protection System are provided to l ensure that an accidental startup of an isolated loop with a lower

! temperature or lower boron concentration than the core and active

. loops will be a .relatively slow event. The interlocks ensure 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 at  ;

least 90 minutes before the cold leg stop valve can be opened. As stated in the FSAR, the interlocks meet the IEEE Standard 279-1971 .

criteria and, therefore, cannot be negated by a single failure. The interlock on hot leg temperature is a backup for the interlock on' cold leg temperature., Thus, the single failure criterion applies to s the combination and- not to each separately. These interlocks function to:

1. Prevent opening a hot leg stop valve unless the cold leg stop  :

valve in the same loop is closed.

2. Prevent starting a reactor coolant pump unless:
a. The cold leg stop valve in the same loop is fully closed, or
b. The hot leg stop valve and the cold leg stop valve are fully closed.
3. Prevent opening a cold leg stop valve unless:
a. The hot leg stop valve in the same loop has been fully opened for at least 90 minutes,
b. The bypass valve in the loop has been opened for at least 90 minutes,

l l

, Att chm:nt D (C:n't)

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,Page 5 b

c. Relief line flow has existed for at least 90 minutes, and
d. The cold leg temperature is within 20'F of the highest cold ,

leg temperature in the other loops and the hot leg  !

temperature is within 20*F- of the highest hot leg ,

temperature in the other loops.

The FSAR uses a value of 250 gpm and is conservative since actual bypass relief line flow is approximately 140 gpm, which if used in the accident analysis, would provide substantially more time for the operator to respond before the shutdown margin is lost.

In accordance with the proposed changes, the isolated loop boron concentration is verified twice to ensure the minimum shutdown margin is satisfied, once within 30 minutes before the hot leg stop valve is opened and again within 30 minutes before the cold leg stop valve is opened. In addition, the shutdown margin in the remainder of the RCS ,

is determined within 30 minutes befora the cold leg stop. valve is opened. These verifications provide adequate assurance that the required shutdown margin is .available prior to isolated loop startup. The other requirements addressed by specification 3.4.1.5.a, operation of the isolated. loop on recirculation flow for ,

at least 90 minutes and differential temperature within 20*F, ensure ,

that the isolated loop is homogeneous with respect to boron concentration and temperature. Specification 3.4.1.5.b provides the shutdown margin requirements for the operating RCS and is consistent with the shutdown margin requirements of specification 3.1.1.2 for Mode 5. Specification 3.4.1.5.c provides the shutdown margin ,

requirements for the isolated loop which is also consistent with the shutdown margin requirements of specification 3.1.1.2 for Mode 5. '

l Since the isolated loop shutdown margin requirements are equivalent to the operating loop requirements, startup of an isolated loop in accordance with the proposed specifications ensures that a reactivity L transient will not occur.

Periodic verification that power has been removed from the isolated loop stop valves provides reassurance that the valves are l

maintained closed and can not be inadvertently opened.

l Based on the above, the proposed changes provide sufficient l administrative controls to ensure a safe isolated loop startup.

l These changes are also consistent with the NRC SER on N-1 operation which requires isolated loop startup only with the plant shutdown.

In the event these administrative controls are ignored, the transient l will happen at a slow enough rate (at least 31 minutes are available before the 1% shutdown margin is lost) for the operator to recognize a dilution event and act to maintain the reactor under control.

Therefore, the proposed changes are safe and do not involve an unreviewed safety question.

, i ATTACHMENT C No Significant Hazards Evaluation Beaver Valley Power Station, Unit No. 1 Proposed Technical Specification Change 166 Basis for proposed no significant hazards consideration determination: The Commission has provided standards for determining whether a significant hazards consideration exists in accordance with 10 CFR 50.92(c). A proposed amendment to an operating license for a facility involves no significant hazards consideration if operation of the facility in accordance with the proposed amendment would not (1) involve a significant increase in the probability or consequence ,

of an accident previously evaluated, (2) create the possibility of a new or different kind of accident from any accident previously evaluated, or (3) involve a significant reduction in a margin of safety.

The proposed changes do not involve a significant hazard consideration becauser

1. Clarification of boron reduction described in specification 3.1.1.3 will reduce the delays encountered during RHR testing, i

RHR startup and in returning an isolated loop to service. RCS boron concentration reduction would be involved only if the boron concentration of water added to the RCS is less than that concentration required to satisfy the minimum shutdown margin for >

the specific mode of operation. Applicable specifications are l referenced to provide the mode dependent shutdown margin requirements which are consistent with the accident analysis assumptions. Therefore, this change will not affect the probability of occurrence or the consequence of an accident previously evaluated.

Currently, the Isolated Loop operating requirements of l specification 3.4.1.4 states that the boron concentration of the isolated loop shall be maintained greater than or equal to that i

of the operating loops. This specification has been revised to i require removal of power from the associated loop isolation valve '

This provides an equivalent effective means of operators.

ensuring that the boron concentration in the reactor will not be subjected to dilution by mixing with potentially low concentration borated water from an isolated loop. Provisions have been incorporated to restore power to the valve operators when the isolated loop startup requirements have been satisfied.

These changes will eliminate the need for periodic isolated loop boron concentration sampling and reduce the doses received when sampling and counting to aid in achieving the ALARA goals.

Therefore, an equivalent means of preventing a boron dilution event is provided so these changes will not increase the probability of occurrence or the consequences of an accident previously evaluated.

b"

, 'Att chm:nt c (c:nt'd)

Page 2 Specification 3.4.1.5 has been revised to specifically address the RCS cold leg stop valves. This specification provides the prerequisites to be satisfied prior to returning an isolated loop to service including an added requirement that the boron concentration of the isolated loop satisfies the applicable shutdown margin requirements. The Applicability Statement has been changed to limit startup of an isolated loop to shutdown conditions, consistent with the NRC SER on N-1 loop operation, i where the plant must be in at least mode 5 to unisolate a loop.

An added surveillance requirement 4.4.1.5.3 verifies the boron concentration of the isolated loop satisfies the required shutdown margin prior to opening the cold leg isolation valves. ,

This specification now consolidates into one specification the administrative controls available to ensure a boron dilution event will not occur during startup of an isolated loop. The l FSAR concerns are satisfied by the requirements of this i

specification, therefore, these changes will not increase the probability of occurrence or the consequences of an accident previously evaluated.  :

The note

  • previously applied to the word dilution in specification 3.9.8.1 has been revised to reflect the note in specification 3.1.1.3 and is also applied to the word reduction.

Borated water added to the RCS will not result in a reduction or dilution in RCS boron concentration as long as the boron i concentration of the water added is greater than that required to  !

! satisfy the shutdown margin requirements for mode 6 identified in l specification 3.9.1. This change is consistent with the 1 provisions of specifications 3.4.1.4 and 3.4.1.5 concerning the addition of borated water to the RCS and in returning an isolated loop to service. Therefore, this change will not increase the  ;

probability of occurrence or the consequence of an accident previously evaluated.

L The bases of specification 3/4.4.1 Reactor Coolant Loops has been l revised to identify the sequence of events and reasons for the changes to specifications 3.4.1.4 and 3.4.1.5.

2. The proposed changes properly define a dilution when adding water ,

i to the RCS and clarify the isolated loop operating and startup i requirements consistent with the FSAR accident analyses. A l

reduction or dilution in RCS boron concentration will exist if water added to the RCS contains boron at a concentration less L than that required to satisfy the minimum shutdown margin. Since ,

i the accident analysis is based on a minimum shutdown margin being I available and these changes require verification of that L requirement, the safety of the plant will not be reduced and

! these changes will not create the possibility of a new or different kind of accident from any accident previously evaluated.

L l

' 'Att:chucnt C (C:nt'd)

.Page 3

3. Shutdown margin requirements vary throughout core life as a function of fuel depletion, RCS boron concentration and RCS Tavg. Administrative procedures are in effect to require higher shutdown margins when the reactor coolant system volume is reduced due to isolated loops or in a drained down (mid-loop) condition. Shutdown margin is a standard method for calculating core reactivity, therefore, the effects of adding borated water to the RCS can be determined and based on shutdown margin without introducing any new or different calculations into the operating requirements. The proposed changes provide clarification of the boron dilution requirements based on satisfying minimum shutdown margin requirements. The minimum shutdown margin satisfies the

. accident analysis assumptions related to boron dilution events and surveillance requirements provide verification of the available shutdown margin, therefore, these changes will not involve a significant reduction in the margin of safety of the plant.

Therefore, based on the above, it is proposed to determine that these. changes do not involve any significant hazard considerations.

i

W ATTACHMENT D UFSAR CHANGES BEAVER VALLEY POWER STATION, UNIT 1 PROPOSED TECHNICAL SPECIFICATION CHANGE NO. 166 These UFSAR changes were previously provided to the NRC as Appendix B to the VANTAGE SH Fuel Upgrade Report in support of Technical Specification Change No. 162 dated 05/09/89.

p, -

, i BVPS-1-UPDATED FSAR Rev. 0 (1/82) momentum balance and the pump characteristics and is based on high estimates of system pressure losses.

Results The calculated sequence of events is shown on Table 14.1-2 for  ;

the three cases analyzed. Figure 14.1-13 through 14.1-21 show the loop coastdowns, the core coastdowns, the nuclear power '

coastdowns, and the average and hot channel heat flux coastdowns for each of the three cases. The minimum DNBR for each of' the  :

three cases is not less than 1.3. ,

conclusions

.The analysis shows that the DNBR will not decrease below the limiting value of 1.30 at any time during the transient. Thus, there will be no cladding damage and no release of fission products.to the Reactor Coolant System. -

14.1.6 Startup of an Inactive Reactor Coolant Loop 14.1.6.1 Identification of Causes and Accident Description 14.1.6.1.1 With Loop Stop Valvet open If the plant is operating with one pump out of service, there is .

reverse flow through the loop due to the pressure difference across the reactor vessel. The cold leg temperature in an inactive loop is identical to the cold leg temperature of the active loops (the reactor core inlet temperature). If the reactor is operated at power, there is a temperature drop across .

the steam generator in the inactive loop and, with the reverse t l flow, the hot leg temperature of the inactive loop is lower than

i. the reactor core inlet temperature.

l Administrative procedures require that the unit be brought to a load of less than 25 percent of full power prior to starting a pump in an inactive loop in order to bring inactive loop hot leg l temperature closer to the core inlet temperature. Starting an L idle reactor coolant pump without bringing the inactive loop hot

) leg temperature close to the core inlet temperature would result in the injection of cold water into the core which causes c rapid reactivity insertion and subsequent power increase.

l:

l' 14.1.6.1.2 With Loop Stop Valves Closed 5

In the case of the plant operated at reduced power with a reactor coolant loop out of service and with the loop stop valves of one of its loops closed there is no flow from the reactor vessel and active loops to the inactive loop and the plant operates much as if it were a unit lacking one loop.

With the stop valves in one loop closed, the isolated section of the loop would be cooler than the temperature of the active i

14.1-17

n i a

BVPS-1-UPDATED FSAR Rev. 0 (1/82) loops. Administrative procedures require that the plant be brought to zero load, the temperature of the isolated loop  ;

brought to within 20 F of the active loops, and the boron

. concentration of the isolated loop verified prior to opening the loop stop valves and returning the loop to service, s

Interlocks are provided to ensure that an accidental startup of l an isolated loop which has a lower temperature or lower boron '

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 Reactor Coolant System takes place ,

through the relief line bypassing the cold leg stop valve for a period of approximately one hour before the cold leg stop valve can be opened. The flow through the relief line is made low (no g 'more than' OOP gpm) so that the temperature and boron g concentration in the isolated loop are brought to equilibrium with the remainder of the system at a relatively slow rate should the administrative procedures be violated and an attempt made to open stop valves when the isolated loop temperatures or boron concentration is lower than that in the core and active loops.  ;

Interlocks are provided to:

1. Prevent opening of a hot leg loop stop valve unless the cold. leg stop valve in the same loop is fully closed.
2. Prevent starting a reactor coolant pump unless:
a. The cold leg loop stop valve in the same loop is fully closed, or i
b. Both the hot leg loop stop valve and cold leg locp stop valve are fully open.

l- 3. Prevent opening of a cold leg stop valve unless:

L a. The hot leg loop stop valve in the same loop has L been fully opened for 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />.

b. The bypass valve in the loop has been opened for 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />.
c. Flow has existed through the relief line for 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />.
d. The cold leg temperature is within 20 F of the highest cold leg temperature in the other loops l- and the hot leg temperature is within 20 F of the j highest hot leg temperature in the other loops.

1 The interlocks are a part of the Reactor Protection System and include the following redundancy:

l l

14.1-18 L

J r BVPS-1-UPDATED FSAR Rev. 0 (1/82) 1

1. Two independent limit switches to indicate that a valve is fully open.
2. Two independent limit switches to indicate [that a  :

valve is fully closed. /

3. Two' differential pressure switches in each line which i bypasses a cold leg loop stop valve to determine 'that  !

flow . exists in the line. ' Flow through the line indicates:

a. The valves in the line are open. i
b. The pump in the isolated loop is running.

The interlocks meet the IEEE 279-1971 criteria and, therefore, y cannot be negated by a single failure. The interlock on hot leg l"

temperatures is a backup for the interlock on cold leg temperatures. Thus, the single failure criterion applies to the combination and not to each separately.

With the above protection system interlocks, the following' l procedure is necessary in order to reopen loop stop valves once '

either stop valve in a loop has left the fully open position.

1. The cold leg loop stop valve must be fully closed before the hot leg stop valve can be returned to its -

fully open position.

i L l 2. Flow must have existed from the isolated portion of the i system to the remainder of the system (maximum rate is 250 ,' approximateMN444- gpm) for at least 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> through the REN line bypasshing the cold leg stop valve and the isolated loop and active loop temperatures must agree within 20 F before the cold leg loop stop valve can be opened.

14.1.6.2 Analysis of Effects and Consequences 14.1.6.2.1 Method of Analysis A detailed digital simulation of the plant, including heat transfer to the steam generators of the active and inactive loops and Reactor Coolant System flow transit times, is used to study the transient following the startup of an idle pump.

Loop Stop Valves Open Assumptions are:

1. Initial conditions of maximum core power and reactor coolant avcrage temperatures and minimum reactor -

coolant pressure resulting in minimum initial margin to DNB. These values are to be consistent with maximum steady state power level allowed with all but 14.1-19 l . ., - - . - . _ . .. . _ _ . . . . - . - - . . . . . . . .'

__ -, as. . . ,

p -

.j p n .;

+ -

L .

'- '6 BVPS-1-UPDATED FSAR Rev. 0 (1/82) one loop in operation including appropriate allowances- _

for calibration and instrument errors. The high  !

initial power gives the greatest temperature difference between the core inlet temperature and the inactive loop hot leg temperature.  ;

i 2.. Following the start of the idle pump, the inactive loop i flow reverses and accelerates to its nominal full flow value.

9

3. A conservatively large (absolute value) negative moderator coefficient associated with the end of life.
4. A conservatively low (absolute value) negative Doppler power' coefficient is used. -
5. The initial reactor coolant loop flows are at the appropriate values for one pump out of service.

g- analysis reactor trip is conservatively assumed to

- actuate he high neutron flux reactor tri trip A setpoint was assi +a be 118 percent of n ull power. In

% practice, however, reac power range-neutron flux w expected to . occur on Permissive P-8 setpoint 3 (set at approxi==* _ percent . of n 1 power). The-p., -

w Permissi setpoint will remain active unti in the e loop reaches 90 percent of its nominal value.

I Loop Stop Valves Closed ,

. The start-up of an inactive reactor coolant loop with the loop stop valves initially closed has been analyzed assuming the inactive loop to be at a boron concentration of 0 ppm while the m active portion of the system is at 1,500' ppm, a conservatively ' igoo high value for beginning of life. The flow through the relief  :

line is assumed at its maximum value of approximatley -!HH) gpm.

REV 2.50 14.1.6.2.2 Results With Loop Stop Valves Open '

The results following the startup of the idle pump, with the loop stop valves initially open are shown in Figure 14.1-22. The minimum DNBR during the transient is never less than=1.30 The sequence of events for the accident is sho on l calculated Table 14.1-2.

With Loop Stop Valves closed hu%=W5 INI E.

Even with the assumption that administrative procedures are violated to the extent that an attempt is made to open the loop stop valves with 0 ppm in the inactive loop _while the remaining,1800 portion of the system is at 1,500' ppm, the dilution of the boron gg,y in the core is slow. The initial reactivity insertion rate is 14.1-20

, DVPS-1-UPDATED FSAR Rev. 0 (1/82) )

pg 3/

calculated to be 3.1 x 10'fak/second to 1.7 x 10~5ak/;econd 7 i considerably less than the rq

.in Section 14.1.2. It takes >getivity insertion rates to 10 minutes'after theconsidered beginning )

l of the dilution before the total shutdown margin is lost assuming i one percent shutdown margin at the beginning of the accident. j This is ample time for the operator to recognize a high count  !

rate signal and terminate the dilution by turning off the pump in the inactive loop or by borating to counteract the dilution. -it- I

- shculd

' ' " 'be

- f urther-poin ted-out--t-hat--the capcsted chutdeva =rgin-

"ginn-ing-ofM-i-fe-i1e af ths crder of 3 perccat-

-rath:: than the i pereent :: u= d ab;ve.

The reactivity addition at end of life due to an attempt to open stop valves when the inactive loop temperature is less than the  ;

core temperature is smaller than the reactivity addition considered in the above beginning of life casa.

14.1.6.2.3 Conclusions -

With Loop Stop Valves Open The transient results show that the core is not adversely affected, i.e. , there is considerable margin to  : limiting 0"On af 1.30. fke Saft $y oul sis y h A N.

With Loop Stop Valves Closed The redundant interlocks provided in the Reactor Protection System insure that the temperature and boron concentration in an isolated loop are brought to equilibrium with the remainder of the system at a slow rate. Should administrative procedures be violated and an attempt made to open stop valves when the isolated loop temperature or boron concentration is lower than that in the core, the reactivity addition rate is slow enough to allow the operator to take corrective action before chutdown margin is lost.

14.1.7 Loss of External Electrical Load and/or Turbine Trip 14.1.7.1 Identification of Causes and Accident Description Major load loss on the plant can result from loss of external electrical load or from a turbine trip. For either case offsite power is available for the continued operation of the plant components such as the reactor coolant pumps. The case of loss of all AC power (station blackout) is analyzed in Section 14.1.11.

For a turbine trip, the reactor would be tripped directly (unless below approximately 10 percent power) from a signal derived frcm the turbine autostop oil pressure (Westinghouse Turbine) and turbine stop valves. The automatic steam dump system would accommodate the excess steam generation. Reactor coolant temperatures and pressure do not significantly increase if the 14.1-21

.7 r,

c.

3 .

L BVPS-1 UPDATED FSAR

14.1.6 Startup of an inactive Reactor Coolant Loop L

L Inserts for Zirc Grids and increased Peaking Factors v.

Insert 1:

The reactor trip is assumed to occur on low coolant loop flow when ,

the power range neutron flux exceeds the P-8 setpoint. The P-8 setpoint is conservatively assumed to be 79 percent of rated power, L

. which corresponds to the nominal setpoint plus 9 percent for nuclear instrumentation errors. ,

y insert 2:

TABLE 14.1-2 (CONT'D)  ;

TIME SE0VENCE OF EVENTS FOR CONDITION II EVENTS Accident Event Time (sec)

Startup of an inactive Reactor Coolant Loop (Loop Stop Valves Open)-

Initiation of RCP 0.0 Power Reached P-8 Trip Setpoint 2.7 Rods Begin to Drop 3.2 Minimum DNBR Occurs 4.4 i

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