ML18153D316

Proposed Tech Specs Re Containment Hydrogen Analyzers

ML18153D316
Person / Time
Site:	Surry
Issue date:	04/21/1993
From:	VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:
Shared Package
ML18153D315	List: ML18153D314 ML18153D316
References
NUDOCS 9304260209
Download: ML18153D316 (11)

Text

e Discussion of Proposed Changes

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e DISCUSSION OF CHANGES INTRODUCTION Technical Specification 3.7, Instrumentation Systems, discusses the requirements for monitoring the containment hydrogen concentration as specified in NUREG-0737, Post TMI Modifications.

The surveillance requirements for the containment hydrogen analyzers are provided in Technical Specification 4.1, Operational Safety Review. The surveillance requirements presently specify a channel check to be performed every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> as well as a monthly functional check and a quarterly calibration test. However, since the containment hydrogen analyzers are maintained in the standby mode, the channel check required every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> is. unnecessary. Furthermore, the required response time for the containment hydrogen analyzers to be operable if a safety injection occurs needs to be included in the Basis discussion of the analyzers in Technical Specification 3.7.

This Technical Specification change request also proposes minor administrative changes.

BACKGROUND NUREG-0737, Section 11.F.1.6, Containment Hydrogen Monitor System, requires that continuous indication of the hydrogen concentration in the containment atmosphere over the range of O to 10% be provided in the control room. This position was later clarified by the NRC to note that 1) continuous indication of the hydrogen concentration is not required during normal operation, and 2) if indication is not provided at all times, continuous indication and recording must be functioning within 30 minutes of the initiation of safety injection.

Generic Letter 83-37, NUREG-0737 Technical Specifications, provided generic Technical Specifications that addressed the containment hydrogen analyzers. These Technical Specifications included surveillance requirements to perform a channel check every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />, a monthly functional check, and a quarterly calibration test. We incorporated these generic changes, with minor revisions, into our Surry Technical Specifications as Amendment 100/99.

As noted in the NRC clarification in item 1 above, the hydrogen analyzers are not required to provide indication during normal plant operation. Consequently, since the analyzers are maintained in the standby mode, the requirement for a channel check every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> serves no useful purpose. Assurance that the analyzers will function when needed is provided by the monthly functional check and the quarterly calibration.

We therefore propose to delete this requirement.

As noted in the NRC clarification in item 2 above, the hydrogen analyzers must be functioning within 30 minutes of the initiation of safety injection. The analyzers installed at Surry have this capability, however, the decision to place them into service is governed by the applicable Emergency Procedures based on existing plant conditions.

Since the required response time for the containment hydrogen analyzers is not presently discussed in the Technical Specification Basis, a paragraph will be added to note the 30 minute response time capability.

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e Minor administrative changes will also be made to Technical Specification Table 4.1-2A to add applicable UFSAR references to two items, to add a superscript to a third item that was inadvertently deleted by a previous amendment, and to make testing frequency terminology consistent.

SPECIFIC CHANGES The Basis Section of Technical Specification 3.7 will be revised to note that the containment hydrogen analyzers can provide continuous indication during accident conditions, and that each hydrogen analyzer is designed with the capability to obtain an accurate sample within 30 minutes after initiation of a safety injection.

Also, the discussion of the hydrogen analyzer heat tracing will be revised to delete the reference to the capability of the heat tracing to bring the hydrogen analyzer process piping to the appropriate operating temperature within 20 minutes. The 20 minute warm-up time is not significant as long as the total 30 minute response time for the hydrogen analyzers is met.

Technical Specification Table 4.1-2A will be revised to delete the requirement in Item 20a to perform a channel check of the containment hydrog~n analyzers every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.

Items 20b and 20c will be renumbered as 20a and 20b, respectively, and new item 20b will be revised editorially for clarity.

Table 4.1-2A, Items 16 and 17, will be revised to add Section 4.3 under the FSAR Reference Section header in the table to reflect the UFSAR section that discusses the reactor vessel overpressure mitigation system.

Table 4.1-2A, Item 18, will be revised to add a (b) superscript that was inadvertently deleted by Technical Specification Amendment 84/83.

Superscript (b) notes the minimum differential pressure allowed for the Primary Coolant System periodic valve leakage testing discussed*in Item 18.

Table 4.1-2A, Items 14a and b, 15 and 17, will be revised to designate their testing frequency as "Each Refueling Shutdown" for consistency in terminology.

SAFETY SIGNIFICANCE The proposed changes delete the requirement for a channel check of the containment hydrogen analyzers once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> in Technical Specification 4.1. The changes also revise the discussion of the containment hydrogen analyzers in the Basis section of Technical Specification 3.7 to clarify the design response time of the analyzers. The remaining proposed changes are administrative in nature to clarify testing terminology, to correct a typographical error and to add UFSAR section references.

The proposed changes do not alter the design or operation of the containment hydrogen analyzers, therefore, they will operate as previously analyzed, and no new failure modes are created. Furthermore, no setpoint or operating parameter is affected by this change. Consequently, operation of the plant in accordance with the proposed changes would not involve an unreviewed safety question.

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e Proposed Technical Specifications

e TS 3.7-9a Instrumentation is provided for monitoring (and controlling) the concentrations of potentially explosive gas mixtures in the waste gas holdup system. The operability and use of this instrumentation is consistent with the requirements of General Design Criteria 60, 63 and 64 of Appendix A to 1 O CFR Part 50.

Containment Hydrogen Analyzers Continuous indication of hydrogen concentration in the containment atmosphere can be provided in the control room over the range of O to 1 O percent hydrogen concentration under accident conditions.

These redundant, qualified hydrogen analyzers are shared by Units 1 and 2 with the capability of measuring containment hydrogen concentration for the range of O to 1 O percent and the installation of instrumentation to indicate and record this measurement. Each hydrogen analyzer is designed with the capability to obtain an accurate sample within 30 minutes after initiation of safety injection.

A transfer switch with control circuitry is provided for the capability of Unit 1 to utilize both analyzers or for Unit 2 to utilize both analyzers.

Each unit's hydrogen analyzer will receive a transferable power supply from Unit 1 and Unit 2. This will ensure redundancy for each unit.

Indication of Unit 1 and Unit 2 hydrogen concentration is provided on Unit 1 PAMC panel and Unit 2 PAMC panel. Hydrogen concentration is also recorded on qualified recorders.

In addition, each hydrogen analyzer is provided with an alarm for trouble/high hydrogen content.

These alarms are located in the

e TS 3.7-9b control room.

The supply lines installed from the containment penetrations to the hydrogen analyzers have Category I Class IE heat tracing applied. The heat tracing system receives the same transferable emergency power as is provided to the containment hydrogen analyzers. The heat trace system is de-energized during normal system operation. Upon receipt of a safety injection signal (Train A or Train B), the system is automatically started, after a preset time delay, to bring the piping process temperature to 250°F +/- 10°F. Each heat trace circuit is equipped with an RTD to provide individual circuit readout, over temperature alarm and cycles the circuit to maintain the process temperatures via the solid state control modules.

The hydrogen analyzer heat trace system is equipped with high temperature, loss of D.C. power, loss of A.C. power, loss of control power and failure of automatic initiation alarms.

Non-Essential Service Water Isolation System The operability of this functional system ensures that adequate intake canal inventory can be maintained by the emergency service water pumps. Adequate intake canal inventory provides design service water flow to the recirculation spray heat exchangers and other essential loads (e.g., control room area chillers, charging pump lube oil coolers) following a design basis loss of coolant accident with a coincident loss of offsite power. This system is common to both units in that each of the two trains will actuate equipment on each unit.

TABLE 4.1-2A (CONTINUED)

MINIMUM FREQUENCY FOR EQUIPMENT TESTS FSAR SECTION DESCRIPTION IEfil FREQUENCY REFERENCE 14a. Service Water System Valves in Functional Each Refueling Shutdown 9.9 Line Supplying Recirculation Spray Heat Exchangers

b. Service Water System Valves Functional Each Refueling Shutdown 9.9 Isolating Flow to Non-essential loads on Intake Canal Low Level Isolation

15.

Control Room Ventilation System

• Ability to maintain positive Each Refueling Shutdown 9.13 pressure for 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> using a volume of air equivalent to or less than stored in the bottled air supply

16.

Reactor Vessel Overpressure Functional & Setpoint Prior to decreasing RCS 4.3 Mitigating System (except temperature below 350°F backup air supply) and monthly while the RCS is < 350°F and the Reactor Vessel Head is bolted

17.

Reactor Vessel Overpressure Setpoint Each Refueling Shutdown 4.3 Mitigating System Backup Air Supply

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DESCRIPTION

18.

Primary Coolant System TABLE 4.1-2A (CONTINUED)

MINIMUM FREQUENCY FOR EQUIPMENT TESTS TEST Functional FREQUENCY FSAR SECTION REFERENCE 1. Periodic leakage testing(a)(b) on each valve listed in Specification 3.1.C. 7a shall be accomplished prior to entering power operation condition after every time the plant is placed in the cold shutdown condition for refueling, after each time the plant is placed in cold shutdown condition for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> if testing has not been accomplished in the A

preceeding 9 months, and prior to returning the valve to W,

19.

Containment Purge MOV Leakage

20.

Containment Hydrogen Analyzers

21.

RCS Flow Functional

a.

Channel Functional Test

b. Channel Calibration Test

1. Sample gas used:

One volume percent

(+/-0.25%) hydrogen, balance nitrogen Four volume percent

(+/-0.25%) hydrogen, balance nitrogen

2. Channel Calibration test will include startup and operation of the Heat Tracing System Flow.:: 273,000 gpm service after maintenance, repair or replacement work is performed.

Semi-Annual (Unit at power or shutdown) if purge valves are operated during interva1(c)

Once per 31 days Once per 92 days on staggered basis Once per refueling cycle 14 (a)

(b)

(c)

To satisfy ALARA requirements, leakage may be measured indirectly (as from the performance of pressure indicators) if accomplished in accordance with approved procedures and supported by computations showing that the method is capable of demonstrating valve compliance with the leakage criteria.

Minimum differential test pressure shall not be below 150 psid.

Refer to Section 4.4 for acceptance criteria.

See Specification 4.1.D.

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Significant Hazards Consideration

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e SIGNIFICANT HAZARDS CONSIDERATION Virginia Electric and Power Company has reviewed the proposed changes against the criteria of 1 O CFR 50.92 and has concluded that the changes as proposed do not pose a significant hazards consideration. The operation of Surry Power Station in accordance with the proposed Technical Specification changes would not:

1.

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

. previously evaluated.

The containment hydrogen analyzers only monitor hydrogen levels in the containment under post-accident conditions; therefore, the device has no influence on probability of accident occurrence. Furthermore, the design and operation of the containment hydrogen analyzers are not altered by the proposed changes. Therefore, deletion of the twelve hour channel check requirement would not increase the consequences of an accident. Assurance that the analyzers will function when needed is provided by monthly functional checks and quarterly calibrations.

The deletion of the 20 minute warm-up time requirement for the hydrogen analyzers' heat tracing is not significant since a statement has been added to the Basis section noting that the hydrogen analyzer must be capable of providing continuous indication within 30 minutes of the receipt of a safety injection signal, which is the design requirement for the analyzer. This time frame encompasses the heat trace warm-up requirement and assures the hydrogen analyzer will be available when needed. Consequently, the probability or consequences of an accident previously evaluated are not increased.

The remaining changes do not increase the probability or consequences of an accident because they are administrative in nature to correct a typographical error, add UFSAR references, and make test frequency terminology consistent and clear.

2.

Create the possibility of a new or different kind of accident from any previously evaluated. The proposed changes do not create a new failure mode as the operation of the analyzers has not been affected, and no physical modifications are being performed. The hydrogen analyzer is a post-accident monitor and therefore cannot create a new or different kind of accident. Assurance that the analyzers will function when needed is provided by monthly functional checks and quarterly calibrations.

Deletion of the 20 minute warm-up time requirement for the hydrogen analyzers' heat tracing is encompassed by the 30 minute operability requirement for the hydrogen analyzers and, consequently, would not create a new or different kind of accident from any previously evaluated.

The remaining changes are administrative in nature to correct a typographical error, add UFSAR references, and make test frequency terminology consistent and clear and would therefore not create a new or different kind of accident.

3.

Involve a significant reduction in a margin of safety. No setpoint or operating parameter is affected by this change. The containment hydrogen analyzers only monitor hydrogen levels in the containment during post-accident conditions, and Page 1 of 2

assurance that the analyzers will function when needed is provided by monthly functional checks and quarterly calibrations. The analyzers are still required to be capable of providing continuous indication within 30 minutes of the receipt of a safety injection signal. Therefore, the deletion of the 12 hour1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> channel check requirement does not reduce the margin of safety.

The deletion of the 20 minute warm-up time requirement for the hydrogen analyzer heat tracing is encompassed by the 30 minute operability requirement for the hydrogen analyzers, and the remaining changes are administrative in nature and do not affect the operation of any system. Therefore, the safety margin is not reduced.

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