ML20214T425

Proposed Tech Specs to Allow Simultaneous Charging Pump Operation During Pump Realignment & to Reduce Allowable Time Period for Depressurization Following Failure of PORV

ML20214T425
Person / Time
Site:	Zion  File:ZionSolutions icon.png
Issue date:	05/29/1987
From:	COMMONWEALTH EDISON CO.
To:
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ML20214T414	List: ML20214T410 ML20214T425
References
NUDOCS 8706100260
Download: ML20214T425 (12)

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ATTACISWff 1 PROPOSED CHANGES TO APPENDIX A TECHNICAL SPECIFICATION SECTIONS 3.3.2.0 and 4.3.2.G LOW TEMPERATURE OVERPRESSURE PROTECTION Pages Modified: 82 83 93 94 Pages Added: 83a 83b 3106K 0706100260 070529

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DR ADOCK 05000295 PDR

LIMITING CON 01110N FOR OPERAT10N SURVEILLANCE REQUIREMENT 3.3.2.G. Low Temperature Overpressure Protection 4.3.2.G. Low Temperature Overpressure Protection t

1.

At least one of the following low 1.

Surveillance and testing of the low temperature protection methods shall be temperature overpressure protection available:

methods shall be performed as follows:

a.

Two power operated relief valves a.

Each PORV shall be demonstrated as (PORVs) with a lift setting of 435 OPERABLE by:

i psig shall be OPERABLE, or 1.

Performance of a CHANNEL FUNC110NAL 1EST on the PORV actuation channel within 31

[

days prior to entering a t

condition in which the PORV is required OPERABLE, and at least once per 31 days thereafter when the PORV is required OPERABLE.

2.

Verifying the PORV backup air l

supply is charged, within 31 days prior to entering a condition in which the PORY is required OPERABLE, and at least i

l once per 31 days thereafter when the PORV is required OPERABLE.

3.

Performance of a CHANNEL CALIBRATION on the PORV actuation channel at least once

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per refueling outage.

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l 09200/09210 82 L

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I LIMITING CONDITION FOR OPERATION SURVEILLANCE REQUIREMENT I

3.3.2.G. Low Temperature Overpressure Protection 4.3.2.G. Low Temperature Overpressure Protection (Continued)

(Continued)

I 4.

Verifying each PORV's isolation valve is open at least once per j

shift when this method is being j

used for low temperature overpressure protection.

b.

The Reactor Coolant System (RCS) b.

The RCS pressure shall be verified pressure shall be less than 100 to be less than 100 psig, and psig, and the pressurizer level less pressurizer level shall be verified than 25%, or to be less than 25% a least once per shift, when this method is being i

used for low temperature overpressure protection.

l c.

The RCS is depressurized and one c.

Verifying one PORY and it's PORV and it's isolation valve are isolation valve are open at least i

open.

once per shift, when this method is being used for low temperature overpressure protection.

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i 2.

A maximum of one* charging pump or safety 2.

At least four of the five pumps (charging injection pump, aligned for injection pumps and safety injection pumps), and I

into the RCS, and no accumulators shall all accumulators, shall be verified to be i

.be OPERABLE.

incapable of injecting into the RCS prior j

to entering a condition in which they are required to be inoperable, and at least once per shif t thereaf ter while they are i

j required to'be inoperable.

For short durations of time during pump switchover, i

two charging pumps may be OPERABLE for the purpose j

of maintaining seal injection flow to the reactor coolant pumps.

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09200/09210 83

LIMITING CONDITION FOR OPERATION SURVEILLANCE REQUIREMENT 3.3.2.G. Low Temperature Overpressure Protection 4.3.2.G. Low Temperature Overpressure Protection (Continued)

(Continued) 3.

When starting a reactor coolant pump, 3.

Not applicable.

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when no reactor coolant pumps are l

running, the temperature in the secondary side of the steam generator in the loop in which the reactor coolant pump is to be started shall be less than 50*F higher than the RCS temperature.

APPLICABILITY:

Mode 4 when the temperature of any RCS cold leg is less than or equal to 250*F, MODE 5 and MODE.6 with the reactor vessel head on.

ACTION:

a.

With one PORV inoperable, restore the inoperable PORY to OPERABLE status within 7 days, or within the next 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> either; Depressurize the RCS to less than 100 psig and lower pressurizer level to less than 25%, or Depressurize the RCS and open at least one PORV and it's block valve.

09200/09210 83a

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LIMITING CONDITION FOR OPERATION SURVEILLANCE REQUIREMENT

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3.3.2.G. Low Temperature Overpressure Protection 4.3.2.G. Low Temperature Overpressure Protection (Continued)

(Continued) b.

With both PORV's inoperable, within l

the next 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> either; Depressu*i e the RCS to less than 10m psig and lower pressurizer level to less than 25%, or Depressurize the RCS and open at least one PORY and it's block valve.

c.

In the event that a PORV is used to mitigate an RCS pressure transient, a SPECIAL REPORT shall be prepared and submitted to the Commission pursuant to Specification 6.6.3.B.

The report shall include the following information:

1.

A description of the circumstances initiating the transient, and 2.

The effect of the PORV's on the transient, and 3.

The corrective action necessary to prevent reoccurrence.

d.

The provisions of Specification 3.0.4 are not applicable.

09200/09210 l83b i

Increase with increasing cooldown rates.

Allowable pressure-temperatur e relat ions ar e gener aleil f or hat h steady-state and Iinite cooldown rate situations.

f rom these relations, composite limit curves are runstructed, for each cooldown rate of interest.

The use of the composite curve in the cooldown analysis is necessary because control of the couldown procedure is based on measurement of reactor coolant temperature, whereas the limiting pressure is actually dependent on the material temperature at the tip of the assumed flaw.

During cooldown, the 1/4I vessel location is at a higher temperature than the fluid adjacent to the vessel ID.

Ihis condition, of course, is not true for the steady-state situation.

It follows that at any given reactor coolant temperature, the Al elevelopeil during cooidown results in a higher value of KIR at the 1/41 location for finite cooldown rates than for steady-state operation, furthermore, if -conditions exist such that the increase in KIR exceeds Kgt, the calculated allowable pressure during cooldown will be greater than the steady-state value.

i lhe above procedures are needed because there is no direct control on temperature at the 1/41 location; therefore, allowable pressures may unknowingly be violated if the rate of cooling is decreased at various intervals along a cooldown ramp.

The use of the composite curve eliminates this problem and assures conservative operation of the system f or the entire cooldown period.

PRESSURIZER LIMIIS Although the pressurizer operates in temperature ranges above those for which there is reason for concern of nonductile failure, operating limits are provided to assure compatibility of operation with the fatigue analysis performed in accordance with the ASME Code requirements.

IlYDROSIATIC IESTING LIMIT CURVE Allowable pressure-temperature relationships for leak and hydrostatic testing are also calculated using methods derived f rom Non-Mandatory Appendix G2000 in Section III of the ASME Doller and Pressure Vessel Code.

Ihe approach specified is the same as described for heatup and cooldown limits except that the safety f actor on Kgg is reduced to 1.5 and there are no significant thernal transients or gradlents.

Thus the governing equation for the leak and hydrostatic testing analysis is:

1.5 Kgg < KIR INADVERTANT SAFETY INJECfl0N

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l In the event of an inadvertant safety injection actuation, the affected reactor will trip immediately, placing the reactor in the hot shutdown condition.

After 60 seconds safety injection may be reset and injection terminated as required. An inspection of the primary system while at hot shutdown will prevent possible degradations in the primary system f rom undergoing f urther inanediate thermal shock Imposed during a cooldown.

If degradations in the primary system are discovered, an orderly controlled cooldown will be planned to minimlie the ef f ec ts of t he r nu l shock on these degradations on the affected unit.

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1 Bases:

Low Temperature Overpressure Protection i

3.2.2.G There are 3 means of protecting the RCS f rom overpressurization by a pressure transient at' low temperatures I

(below 250*F). The first type of protection is ensured by the operation and surveillance of the power 4.2.2.G operated relief valves with a lif t setting of 435 psig. A single power operated relief valve (PORV) will.

i relieve a pressure transient caused by 1) a mass addition into a solid RCS from a charging pump or 2) a heat i

I input based on a reactor coolant pump being started in an idle RCS and circulating water into a steam generator whose temperature is 50*F greater than the RCS temperature.

(1)

The second means of protection is ensured by a PORV being open.

It will have the same relieving capabilities j

as mentioned above.

i The third means of protection limits the pressurizer level to 25% and the pressurizer pressure to 100 psig.

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A pressure transient caused by the inadvertent mass addition from a charging pump running for 10 minutes will be relieved by the large gas volume and low pressure present in the pressurizer as' mentioned above.

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Maintaining the pressurizer level below 25% will als.o make the hi pressurizer level deviation alarm available j

to the operator during a mass addition accident.

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In the event that a single PORV becomes inoperable, the repair period of 7 days is based on allowing 4

I sufficient time to effect repairs using safe and proper procedures and upon the operability of the redundant

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PORV.

The 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> time period to reach the restrictive conditions in the pressurizer provides sufficient i

time to meet these conditions.

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a i

In the event that both PORV's become inoperable, the condition is more serious than for a single inoperable PORV, therefore every attempt should be made to depressurize the RCS in a controlled manner as rapidly as j

possible. The 16 hour1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> time period to reach the restrictive conditions in the pressurizer represents a l

reasonable amount of time to meet these conditions under an expedited circumstance.

The Low Temperature Overpressure Protection System must be tested on a periodic bases consistent with the need for its use. A CHANNEL FUNCTIONAL TEST shall be performed prior to enabling the overpressure protection system during cooldown and startup.

i The limitations and surveillance requirements on the ECCS equipment provides assurance that a mass addition pressure transient can be relieved by the operation of a single PORV or the limiting conditions placed on the i

2 pressurizer.

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The restrictions for startup of a RCP limits the heat input accident to within the relieving capabilities of j

a single PORV.

(1)

Pressure Mitigating Systems Transient Analysis Results July 1977 Westinghouse Owners Group on RCS

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Overpressurization.

j 09200/09210 94

ATTACHMENT 2 COMPARISON WITH THE STANDARDIZED TECHNICAL SPECIPICATIONS (STS),

The purpose of this proposed change is threefold:

1.

This change is intended to reflect the STS Format.

2.

This proposed amendment will allow increased flexibility during low temperature operations to permit simultaneous charging pump operation for a short time duration during pump switchover operations.

3.

The allowable time period for depressurizing the reactor coolant system (RCS) following the failure of two PORVs will be reduced.

The major differences between proposed amendment and the STS are discussed below.

ITEM 1.

Section 3.4.9.3 of the STS identifies two methods for low temperature over pressure protection.

A.

Two power operated release valves (pORV) must be operable, or B.

The RCS is to be depressurized with an open vent path Both the current Zion technical specifications and the proposed amendment include the above two options, with the substitution of an open PORV for the specified RCS vent.

In addition, the proposed amendment includes the option to permit RCS pressure to be reduced to less than 100 psig concurrent with pressurizer level less than 25%.

All three methods discussed above currently exist in the Zion Technical Specifications. The basis for these methods are contained on page 94 of the existing Technical Specifications. Thus, this proposed amendment does not explicitly involve the approval of new low temperature over pressure protection methods.

ITEM 2.

The proposed amendment has included the restrictions on charging pump, safety injection pump, and accumulator operation. These restrictions are unchanged from the existing Zion Technical Specification.

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' However, the flexibility to allow two charging pumps to operate for short periods of time for the purpose of maintaining seal injection flow to the reactor coolant pumps has been added. The purpose of this clause is to maintain the cleaner seal injection flow to the RCP seals during charging pump realignment. This will prevent the backflow of RCS water through the RCP seals when the seal injection flow has been interrupted which will help prevent RCP seal failure.

ITEM 3.

The action statement for STS section 3.4.9.3 requires that the RCS be vented within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> following the inoperability of one PORV for greater than 7 days or the ineperability of two PORV's.

The proposed amendment incorporates 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> and 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br />, respectively, for venting the RCS subsequent to the above conditions.

These time periods reflect Zion Stations belief that it is difficult to depressurize the RCS in a controlled manner in 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />. The initial conditions for such an operation would include a steam bubble within the pressurizer. Thus the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> limit, which exists within the current Zion technical specifications, represents a reasonable time frame in which to 4

depressurize the RCS event the failure of only one PORV.

However, Zion Station recognizes that the inoperability of two PORV's is a more serious situation and that every attempt should be made to depressurize the RCS in a controlled manner as rapidly as possible.

Therefore, a 16 hour1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> time period is proposed as the minimum amount of time in which the depressurization could proceed in a controlled manner. This 16 hour1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> time period is more restrictive than the 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> allowed by the existing Zion Technical Specifications.

ITEM 4.

The STS incorporates the requirement for the performance of I

ASME boiler and pressure code surveillances in the pORV technical specification section. The existing Zion specifications address these test requirements in specification 3.3.2.E.

Therefore, they are not repeated in I

this proposed amendment.

In summary this proposed change incorporates the following major elements:

1.

Reformating Zion Technical Specification sections 3.3.2.G and 4.3.2.0 to the STS format.

2.

Incorporating flexibility to allow the operation of two centrifugal charging pumps for short periods of time during the realignment of operating charging pumps.

3.

Clarifying the allowable time period for depressurizing the RCS following the failure of PORVs.

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ATTAQ9ENT 3 4

EVALUATION OF SIGNIFICANT HAZARDS CONSIDERATION PROPOSED CHANGES TO ZION TECHNICAL SPECIFICATION APPENDIX A - SECTIONS 3.3.2.0 and 4.3.2.0

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LOW TEMPERATURE OVERPRESSURE PROTECTION 1

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DESCRIPTION OF AMENDMENT REQUEST l

I An amendment to the Zion Facility Operating License is proposed to; a)

Incorporate the format and guidance of NURBG-0452, Rev. 4.

b)

Allow simultaneous charging pump operation for a short time duration s

while low temperature conditions exist and pump switchover operations are in progress.

j c)

Reduce the allowable time period for depressurizing the RCS following the failure of two PORVs.

l BACKGROUND l

i 10 CPR 50.92 states that a proposed amendment will involve a no significant hazards consideration if the proposed amendment does not:

1 (1) Involve a significant increase in the probability or consequences of an accident previously evaluated; or I

(2) Create the possibility of a new or different kind of accident from l

any accident previously evaluated; or I

i (3) Involve a significant reduction in a margin of safety.

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In addition, the Commission has provided guidance in the practical i

application of these criteria by publishing eight examples in 48 FR 14870.

The discussion below addresses each of these three criteria and demonstrates that the proposed amendment involves a no significant hazards j

consideration.

i BASIS FOR NO SIGNIFICANT HAZARDS CONSIDERATION DETERMINATION I

Does the proposed amendment (1) Involve a significant increase in the probability or consequences of an accident previously evaluated; or 1

(2) Create the possibility of a new or different kind of accident from

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any accident previously evaluated; or j

(3)

Involve a significant reduction in a margin of safety?

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. DISCUSSION - ITEM #1 An amendment to the Zion Facility Operating License is proposed to; a)

Incorporate the format and guidance of NUREG-0452, Rev. 4.

b)

Allow simultaneous charging pump operation for a short time duration while low temperature conditions exist and pump switchover operations are in progress.

c)

Reduce the allowable time period for depressurizing the RCS following the failure of two PORVs.

The incorporation of the guidance contained in the Standard Technical Specification MUREG-0452, Rev. 4, provides needed clarification and guidance to Sections 3.3.2.0 and 4.3.2.0 of the Zion Technical Specifications. The incorporation of the STS's guidance constitute expanded and clarified constraints on the operation of Zion Station. The reduction of the allowed time period for RCS depressurization following the failure of two PORV's constitutes a more conservative restriction on Zion's operation.

The inclusion of the flexibility to allow two operating charging pumps during pump switchover operations will increase the reliability of Zion's RCPs.

If the injection of filtered water is interupted, then RCS water backs up into the seal region of the RCP. Minute amounts of debris in this water can cause damage to the seals on an operating RCP. This would result in the need for an RCS depressurization for RCP seal repair. Thus, the maintenance of active seal injection eliminates the introduction of the debris-laden RCS water and promotes more reliable operation of the RCPs.

The charging pump switchover operation occurs quickly. The simultaneous operation of two charging pumps is not expected to last more than approximately five minutes. Thus, the total time of dual pump operation is negligible and is consistent with the pre-existing intent of the limitations on pump operations.

In addition, this operation is required to be performed by a licensed reactor operator, i

Since changes (a) and (c) above both represent more conservative I

and clarified requirements on the operation of Zion Station, there can be no i

adverse effect on the performance of any Zion system or structure.

In addition, change (b) will provide for more reliable RCP operation while involving a negligible amount of dual pump operation.

Based upon the above information, the proposed amendment will not adversely affect the safety performance of any Zion system or structure and will have no effect on any previously evaluated accident.

Therefore this proposed amendment does not involve a significant increase in the probability of or consequences of any accident previously evaluated.

o DISCUSSION #2 The incorporation of the three changes discussed above will have no adverse effect on any of Zion's systems or structures. There will be no change in the normal operation of Zion's low temperature overpressure protection system. Thus, there can be no potential for any previously unanalyzed malfunction or component failure.

The low temperature overpressure protection system is intended to protect the RCS from pressure transients below 250*F.

These transients include the effects of inappropriate operation of charging pumps and RCPs.

These accident sequences have been reviewed and based on the lack of system interaction discussed above, the proposed amendment of the Zion Technical Specifications will not affect any of these preexisting accident sequences.

l Thus this proposed amendment does not create the possibility of a j

new or different kind of accident from those previously evaluated.

DISCUSSION #3 l

The three changes discussed above will not affect the safety function of the low temperature overpressurization system. The low temperature overpressurization system will remain available to perform the intended safety function.

Since the low temperature overpressurization systen's ability to effectively protect the RCS from pressure transients below 250*P will be i

l unaltered by this proposed change, there will be no change in the margin of l

safety.

This proposed change involves the expansion and clarification of l

the affected sections, the reduction of allowed action time periods, and a l

clarification of a pre-existing requirement. Thus, examples (i) and (ii) are applicable in this instance. Examples (1) and (ii) read as follows:

(1) A purely administrative change to Technical Specifications:

for example, a change to achieve consistency throughout the Technical Specification, correction of an error, or a change in nomenclature, (ii) A change that constitutes an additional limitation, restriction, or control not presently included in the Technical Specifications for example, a more stringent surveillance requirement.

l Therefore, since the application for amendment satisfies the criteria specified in 10 CFR 50.92 and is similar to examples for which no significant hazards consideration exists, Commonwealth Edison Company has made a determination that the application involves no significant hazards I

consideration.

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