ML20077J818

Proposed Tech Specs,Changing & Clarifying Requirements for Controlling Potentially Flammable Gases in Waste Gas Decay Tank

ML20077J818
Person / Time
Site:	North Anna
Issue date:	07/30/1991
From:	VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:
Shared Package
ML20077J805	List: ML20077J802 ML20077J818
References
NUDOCS 9108050147
Download: ML20077J818 (7)

Text

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Attachment 1 2

Changes for North Anna Unit 1 l -l y- ,

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b Virginia Electric and Power Company l

r 9108050147 910730

- PDR ADOCK 05000338 P PDR

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RADIOACTIVESTORAGE 3/4.11.2 GAS STORAGE EXPLOSIVE GAS MIXTURE UMITING CONDITIONS FOR OPERATION __

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

l APPLICABILITY: At all times.

ACTION-

a. With the concentration of oxygen in the affected waste gas decay tank greater than 2% l 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 affected waste gas dacay tank greater than 4%

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 without delay, then continue with Action "a" above,

c. With the requirements of Action "a" not satisfied, immediately suspend all additions of waste gases to the affected tank until the oxygen concentration is restored to less than 2% by volume, and submit a Special Report to the commission pursuant to Specification 6.9.2 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, and

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

d. The provisions of Specifications 3.0.3 and 3.0.4 are not applicable.

SURVEILLANCE REOUIREMENTS 4.11.2.5 The concentration of oxygen in the waste gas decay tanks shall be determined to be within the above limits by continuously monitoring the waste gases in the inservice waste gas decay tank with the oxygen monitor required OPERABLE by Table 3.3-14 of Specification 3.3.3.11.

l NORTH ANNA - UNIT 1 3/4 11-4 Amendment No.

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Attachment 2 Changes for North Anna Unit 2 Virginia Electric and Power Company k

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RADOACTIVE STORAGE 3/4.11.2 GAS STORAGE EXPLOSIVE GAS MIXTURE UMITING CONDITIONS FOR OPERATION 3.11.2.5 The concentration of oxygen in the waste gas decay tanks shall be limited to less than or equal to 2% by volume whenever the hydrogen concentration could exceed 4% by volume.

APPLICABILITY: At all times.

ACTON:

a. With the concentration of oxygen in the affected waste gas decay tank greater than 2% l 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 affected waste gas decay tank graater than 4%

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 without delay, then continue with Action "a" above.

c. With the requirements of Action "a" not satisfied, immediately suspend all additions of waste gases to the affected tank until the oxygen concentration is restored to less than 2% by volume, and submit a Sp6cial Report to the commission pursuant to Specification 6.9.2 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, and

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

d. The provisions of Specifications 3.0.3 and 3.0.4 are not applicable.

1 SURVEILLANCE REQUIREMENTS 4.11.2.5 Tho concentration of oxygen in the waste gas decay tanks shall be determined to be within the above limits by continuously monitoring the waste gases in the inservice waste gas decay tank with the oxygen monitor required OPERABLE by Table 3.3-14 of Specification 3.3.3.11.

l l NORTH ANNA- UNIT 2 3/4 11-4 Amendment No.

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' Discu;9lon- of Proposed Change North Anna Units 1 and 2 -

. This discussion was originally

- submitted in support of our j-: October 22,1990 amendment request.

It has been revised to reflect the changes

proposed in tN> Jubmittal. Change bars indicate where

'a 3 visit" s have occurred.

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. Discussion of Proposed Changes The proposed North Anna Technical Specification changes will simplify and clarify the -

Waste Gas Decay Tank (WGDT) explosive gas monitoring requirements.

The-proposed changes to Technical Specification 3.11.2.5 will require the oxygen concentration of the WGDT be maintained less than 2% by volume at all times, whenever the hydrogen concentration could exceed 4% by volume. This change conservatively assumes the worst case hydrogen concentration unless the tank is taken out of service for maintenance and purged with air. Therefore the Unit 1 Table 3.3-14 and Unit 2 Table-3.3-13 Technical Specification requirement to maintain a hydrogen monitor operable and the corresponding surveillance requirements are no longer applicable and aro being removed by this proposed change.

In Table 3.3-14 for Unit 1 and Table 3.313 for Unit 2, which list the required explosive

. gas monitoring instrumentation, item 2a, the hydrogen monitor is deleted. Item 2b is changed to 2a. . The oxygen monitor by itself will be used to ensure a non-explosive mixture by assuming that hydrogen is always present.

The first sentence of " ACTION 32"in the same tables is deleted. This removes the 14 day requirement and allows continued use of the system, provided that grab samples are taken and analyzed. The 14 day requirement in ACTION 32 would only be applicable if 2 independent analyzers were installed to monitor WGDT oxygen concentration. The WGDTs have only one monitor, therefore the 14 days of operation and subsequent daily grab samples with less than the required minimum channels operable is not applicable.

In Table 4.3-14,4.3-13 for Unit 2, which lists the surveillance requirements for l explosive gas monitoring instrumentation, item 2a and its associated footnote 3 is deleted. This reflects the removal of the hydrogen monitor. Item 2b is changed to 2a and footnote 4 is changed to-1.

Specification 3/4.11.2.5 is changed to eliminate dependance on the hydrogen L

monitoring. The phrases "whenever the hydrogen c.oncentration exceeds 4% by l

volume and is less than 96% by volume" is changed to "whenever the hydrogen concentration could exceed 4% by volume " The phrases "and the hydrogen concentration greater than 2% by volume" and " hydrogen and" are deleted.

" Concentrations" and " monitors" are changed to singular. The effect of this change is to assume worst case hydrogen concentration unless the tank is taken out of service for maintenance.

Specification 3/4.11.2.5 is also changed to clarify the requirements. The phrases

" waste gas decay tanks"in ACTIONS a sod b are changed to affected waste gas decay.

tank." " System"in ACTION b is changed to 'aifected tank." " Waste gas decay tanks"in the surveillance requirement is changed to "in service waste gas decay tank." This makes it clear that the requirements only apply to the tank that has the potentially explosive mixture.

The ACTION statements are also changed to provide a graded response in ACTION b, "2% by volume without delay" is changed to "4% by volume without delay, then continue with ACTION a above." The 2% limit is not needed because it is in ACTION

a. ACTION c is changed to d and a new ACTION c is inserted: "With the requirements of Action "a" not satisfied,immediately suspena all additions of waste gases to the affected tank until the oxygen concentration is restored to less than 2% by volume, and submit a Special Report to the commission pursuant to Specification 6.9.2 within the next 30 days outlining the following: 1. The cause of the waste gas decay tank exceedirig then 2% oxygen limit,2. the reason why the oxygen concentration could not be returned to within limits, and 3. actions taken and the time required to return the oxygen concentration to within liinits." The old Specification did not say what to do if the requirements are not met.

The bases for Specification 3/4.11.2.5 is changed to reflect the independence from hydrogen monitoring. The phrase "the concentration of hydrogen and oxygen below their flammability limits" is changed to " oxygen below the concentration that will support combustion at any concentration of hydrogen."

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