ML18153D072

Proposed TS 3.7 Re Instrumentation Sys,Table 3.7-5(a) Re Explosive Gas Monitoring Instrumentation & 3.11 Re Radioactive Gas Storage

ML18153D072
Person / Time
Site:	Surry
Issue date:	07/28/1992
From:	VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:
Shared Package
ML18153D071	List: ML18153D070 ML18153D072
References
NUDOCS 9208050027
Download: ML18153D072 (15)

Text

ATTACHMENT 1 SURRY POWER STATION PROPOSED TECHNICAL SPECIFICATION CHANGES

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e 3.7 INSTRUMENTATION SYSTEMS Operational Safety Instrumentation Applicability Applies to reactor and safety features instrumentation systems.

Objectives TS 3.7-1 To ensure the automatic initiation of the Reactor Protection System and the Engineered Safety Features in the event that a principal process variable limit is exceeded, and to define the limiting conditions for operation of the plant instrumentation and safety circuits necessary to ensure reactor and plant safety.

Specification A.

During on-line testing or in the event of a subsystem instrumentation channel failure, plant operation at RATED POWER shall be permitted to continue in accordance with Tables 3.7-1 through 3.7-3.

B.

The Reactor Protection System instrumentation channels and interlocks shall be OPERABLE as specified in Table 3.7-1.

C.

The Engineered Safeguards Actions and Isolation Function Instrumentation channels and interlocks shall be OPERABLE as specified in Tables 3.7-2 and 3.7-3, respectively.

D.

The Engineered Safety Features initiation instrumentation setting limits shall be as stated in Table 3.7-4.

E.

The explosive gas monitoring instrumentation channel shown in Table 3.7-5(a) shall be OPERABLE with its alarm setpoint set to ensure that the limits of Specification 3.11.A.1 are not exceeded.

1.

With an explosive gas monitoring instrumentation channel alarm setpoint less conservative than required by the above specification, declare the channel inoperable and take the action shown in Table 3.7-5(a).

TABLE 3.7-5(a)

EXPLOSIVE GAS MONITORING INSTRUMENTATION Instrument 1. Waste Gas Holdup System Explosive Gas Monitoring System Oxygen Monitor Total No.

of Channels 1

Minimum OPERABLE Channels 1

1 ACTION 1 -

With the number of OPERABLE channels less than required by the Minimum OPERABLE Channels requirement, operation of this waste gas hold up system may continue provided grab samples are collected 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 analyzed within the following 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.

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TS 3.11-1 3.1*1 RADIOACTIVE GAS STORAGE Applicability Applies to the storage of radioactive gases.

Objective To establish conditions by which gaseous waste containing radioactive materials may be stored.

Specifjcatio n A.

Explosive Gas Mixture

1..... The concentration of oxygen in the waste gas holdup system shall be limited to less than or equal to 2% by volume whenever the hydrogen concentration could exceed 4% by volume.

a.

With the concentration of oxygen in the waste gas holdup system greater than 2% by volume but less than or equal to 4% by volume, reduce the oxygen concentration to the above limits within 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />.

b.

With the concentration of oxygen in the waste gas holdup system greater than 4% by volume, immediately suspend all additions of waste gases to the affected tank and reduce the concentration of oxygen to less than or equal to 4% by volume, then take the action in 1.a above.

c.

With the requirements of action 1.a above not satisfied, immediately suspend all additions of waste gases to the affected tank until the oxygen concentration is restored to less than or equal to 2% by volume, and submit a special report to the Commission within the next 30 days outlining the following:

(1)

The cause of the waste gas decay tank exceeding the 2% oxygen limit.

(2)

The reason why the oxygen concentration could not be returned to within limits.

8.

Basis e

TS 3.11-2 (3)

The actions taken and the time required to return the oxygen concentration to within limits.

2.

The requirements of Specification 3.0.1 are not applicable.

Gas Storage Tanks

1.

The quantity of radioactivity contained in each gas storage tank shall be limited to less than or equal to 24,600 curies of noble gases {considered as Xe-133).

2.

With the quantity of radioactive material in any gas storage tank exceeding the above limit, immediately suspend all addition of radioactive material to the tank and within 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> reduce the tank contents to within the limits.

3.

The requirements of Specification 3.0.1 are not applicable.

Explosive Gas Mixture Specification 3.11.A is provided to ensure that the concentration of potentially explosive gas mixtures contained in the waste gas holdup system is maintained below the flammability limits of hydrogen and oxygen.

Maintaining oxygen below the concentration that will support combustion at any concentration of hydrogen provides assurance that the releases of radioactive materials will be controlled in conformance with the requirements of General Design Criterion 60 of Appendix A to 10 CFR 50.

Gas Storage Tanks The tanks included in Specification 3.11.B are those tanks for which the quantity!

of radioactivity contained is not limited directly or indirectly by another Technical Specification to a quantity that is less than the quantity which provides assurance that in the event of an uncontrolled release of the tank's contents, the resulting total body exposure to an individual at the nearest exclusion area boundary will not exceed 0.5 rem in an event of 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />.

TS 3.11-2a I Restricting the quantity of radioactivity contained in each gas storage tank provides* assurance that in the event of an uncontrolled release of the tank's contents, the resulting total body exposure to an individual at the nearest exclusion area boundary will not exceed 0.5 rem. This is consistent with Branch Technical Position ETSB 11-5 in NUREG-0800, July 1981.

TS 4.1-1 4.1 OPERATIONAL SAFETY REVIEW Applicability Applies to items directly related to safety limits and limiting conditions for operation.

Objective To specify the minimum frequency and type of surveillance to be applied to unit equipment and conditions.

. Specification A.

Calibration, testing, and checking of instrumentation channels. and interlocks shall be performed as detailed in Tables 4.1-1, 4.1-1 A, and 4.1-2.

B.

Equipment tests shall be performed as detailed in Table 4.1-2A and as below.

1.

In addition to the requirements of 4.0.3, each Pressurizer PORV and block valve shall be demonstrated OPERABLE by:

a.

Performing a complete cycle of each PORV with the reactor coolant average temperature >350°F at least once per refueling cycle.

b.

Performing a complete cycle of the solenoid air control valve and check valves on the air accumulators in the PORV control system at least once per refueling cycle'.

TABLE 4.1-1A EXPLOSIVE GAS MONITORING INSTRUMENTATION REQUIREMENTS CHANNEL DESCRIPTION 1. Waste Gas Holdup System Explosive Gas Monitoring System Oxygen Monitor CHANNEL CHECK D

(1)

The channel calibration shall include the use of standard gas samples containing a nominal:

1.

one volume percent oxygen, balance nitrogen, and

2.

four volume percent oxygen, balance nitrogen D -

Daily M -

Monthly Q -

Quarterly CHANNEL CALIBRATION 0(1)

CHANNEL FUNCTIONAL TEST M

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e TS 4.9-1 4.9 RADIOACTIVE GAS STORAGE MONITORING SYSTEM Applicability Applies to the periodic monitoring of radioactive gas storage.

Objective To ascertain that waste gas is stored in accordance with Specification 3.11.

Specification

.... A.,,.. The concentration of oxygen in the waste gas holdup system shall be determined to be within the limits of Specification 3.11.A by continuously monitoring the waste gases in the waste gas holdup system with the oxyg.en monitor required to be OPERABLE by Table 3.7-5(a) of Specification 3.7.E.

B.

The quantity of radioactive material contained in each gas storage tank shall be determined to be within the limits of Specification 3.11.B at least once per month when the specific activity of the primary reactor coolant is s; 2200 µCi/gm dose equivalent Xe-133.

Under the conditions which

. result in.a specific activity > 2200 µCi/gm dose equivalent Xe-133, the waste gas decay tanks shall be sampled once per day.

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ATTACHMENT 2 SURRY POWER STATION DISCUSSION OF PROPOSED CHANGES AND SIGNIFICANT HAZARDS CONSIDERATION DETERMINATION

DISCUSSION OF PROPOSED CHANGES INTRODUCTION Hydrogen and oxygen concentrations in the waste gas decay tank (WGDT) are monitored per Technical Specification 3.11.A to ensure the oxygen concentration is limited to less than or equal to 2% whenever hydrogen concentration exceeds 4%.

The basis for this requirement is to ensure the concentration of potentially explosive gases contained in the waste gas holdup system is maintained below the flammability limits for the combination of hydrogen and oxygen.

Maintaining the concentration of oxygen below the concentration that will support combustion regardless of the concentration of hydrogen provides assurance that releases of radioactive materials will be controlled in accordance with the requirements of General Design Criterion 60 of Appendix A to 10 CFR Part

50.

BACKGROUND Technical Specification 3.11.A.1 limits the concentration of oxygen in the waste gas holdup system to less than or equal to 2o/o by volume whenever the hydrogen concentration exceeds 4% by volume.

During normal operation, hydrogen concentration almost always exceeds 4%.

The hydrogen requirement, although providing additional operational flexibility, is not normally needed or used to ensure concentrations are below explosive mixtures.

Consequently, compliance with the Technical Specifications is maintained by limiting oxygen concentration to less than or equal to 2% by volume.

Technical Specification 3.7.E requires explosive gas monitoring instrumentation channels shown in Table 3.7-S(a) to be operable with their alarm setpoints set to ensure the limits of Technical Specification 3.11.A.1 are not exceeded.

With the number of operable channels less than required, Technical Specification Table 3.7-S(a) allows continued operation of the waste gas holdup system provided grab samples are collected once per twenty-four hours and analyzed within the following four hours.

If the instrumentation can not be returned to service within thirty days, Technical Specification 3.7.E.2 requires a special report be prepared to explain why the inoperability was not corrected in a timely manner.

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e As, long as the concentration* of oxygen is maintained below the level that will support combustion regardless of the concentration of hydrogen, an explosive gas mixture will not result in the waste gas holdup system.

Consequently, if the hydrogen concentration is assumed to be greater than 4% by volume, the limit for which hydrogen - monitoring was being performed, explosive gas control can be maintained by monitoring and limiting oxygen concentration to less than or equal to 2% by volume.

Therefore, the Technical Specifications are being revised to delete the requirement to monitor hydrogen concentration in the waste gas holdup system.

Explosive gas mixture control will be maintained by monitoring and limiting the concentration of oxygen.

The proposed Technical Specifications are similar to those provided in Section 3.11.2.5.A of NUREG-

0472, "Standard Radiological Effluent Technical Specifications for Pressurized Water Reactors."

Additionally, a new reporting requirement is being -- added as Technical Specification 3.11.A.1.c.

The Technical Specifications do not presently specify required actions if oxygen concentration exceeds the limit of Technical Specification 3.11.A.1.a and is not returned to below that limit within the specified time.

Consequently, an additional action is being included to require a thirty day special report if the action required by Technical Specification 3.11.A.1.a is not met.

In addition, administrative changes have been incorporated for consistency with NUREG-0452, Revision 4, "Standard Technical Specifications for Westinghouse Pressurized Water Reactors."

The changes include capitalization of the Technical Specification "defined" words contained in these sections and reformatting tables.

Additional administrative changes were previously submitted in a separate Technical Specification change and are indicated by double change bars in the right margin.

PROPOSED TECHNICAL SPECIFICATION CHANGES Technical Specifications 3.7.E, 4.1.B and Table 3.7-S(a) are being revised to capitalize the Technical Specification defined word "OPERABLE" for consistency with Standard Technical Specifications.

Technical Specification 3.7.E is being revised to indicate only one explosive gas monitoring channel is required for operability. The section is also being modified to refer to "alarm/trip" setpoint as "alarm" setpoint consistent with the actual function of the instrumentation.

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Technical Specification Table 3.7-5(a) is being revised to delete the operability requirements for the hydrogen monitor and a "Total No. Of Channels" column is being added for consistency with the other tables in this section.

Technical Specification 3.11.A.1 is being revised to replace the word 11exceedsn with the phrase 11could exceed 11 to consider the normal operation of the waste gas holdup system with the hydrogen concentration in excess of 4%.

Technical Specification 3.11.A.1.b is being revised to specifically reference Technical Specification 3.11.A.1.a as the required action once Technical Specification 3.11.A.1.b is met.

In addition, Technical Specification 3.11.A.1.c is being added to require a special report to be submitted to the NRC within thirty days if the requirements of Technical Specification 3.11.A.1.a are not met.

The report will be required to include the following information: 1) the cause of the WGDT exceeding the 2%

oxygen limit, 2) the reason the oxygen concentration could not be returned to within limits, and 3) the actions taken and the time required to return the oxygen concentration to within the specified limits.

The Basis of Technical Specification 3.11 is also being changed to delete the reference to maintaining hydrogen concentration within specified limits.

Technical Specification 4.1.A is being revised to add "Table 4.1-1 A" to this section for completeness.

The hydrogen monitor surveillance requirements are being deleted from Technical Specification Table 4.1-1 A.

Technical Specification 4.9.A is being revised to delete the references to hydrogen concentration and the hydrogen monitor.

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SAFETY SIGNIFICANCE The operation of the waste gas holdup system will not be changed as a result of these Technical Specification changes, nor are any new accident precursors introduced.

The oxygen concentration in the WGDT is monitored and controlled to less than or equal to 2% by volume to prohibit the generation of an explosive gas mixture.

Limiting the concentration of oxygen in the tank to below the concentration that will support combustion regardless of the hydrogen concentration will preclude an explosive gas mixture.

Additional restrictions on the hydrogen concentration are not necessary.

The UFSAR has previously considered the failure of the waste gas decay tank and the total release of its contents to the atmosphere and determined that site boundary doses would be within 10 CFR 100 limits.

These proposed changes do not alter the conclusions of the existing safety analysis.

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SIGNIFICANT HAZARDS CONSIDERATION Virginia Electric and Power Company has. reviewed the proposed changes against the criteria of 10 CFR 50.92 and has concluded that the changes as proposed do not pose a significant hazard consideration.

The operation of Surry Power Station in accordance with the proposed Technical Specification changes would ensure an explosive gas mixture does not develop in the waste gas holdup system and consequently would not:

1.

Involve a significant increase in the probability or consequences of an accident previously evaluated.

The probability of a hydrogen explosion in the waste gas holdup system is not increased, since the contents of the system will continue to be monitored to ensure oxygen remains below explosive limits.

The consequences of an accident are not increased,* since the rupture and total release of the contents of the WGDT have been previously considered in the UFSAR and determined to be within 1 O CFR 100 site boundary dose limits.

2.

Create the possibility of a new or different kind of accident from any previously evaluated.

The proposed change does not create a new failure mode.

The waste gas holdup system will continue to be operated in its present manner and monitored to ensure an explosive gas mixture does not develop.

Therefore, no new accidents or malfunction scenarios are introduced by this change.

No accident consequences other than those previously evaluated in the UFSAR are introduced by this change. Furthermore, this change does not affect any accident analysis assumption.

3.

Involve a significant reduction in a margin of safety.

The explosive gas mixture limitations on the contents of the waste gas holdup system remain in place and are appropriately monitored.

Furthermore, failure of the WGDT has been previously analyzed in the UFSAR and the proposed changes do not alter the conclusions of the existing analysis.

Therefore, the safety margin is not reduced.

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