ML18153C272

Proposed Tech Specs Re Main Control Room & Emergency Switchgear Room Air Handling Units

ML18153C272
Person / Time
Site:	Surry
Issue date:	06/26/1990
From:	VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:
Shared Package
ML18153C271	List: ML18153C270 ML18153C272
References
NUDOCS 9007030069
Download: ML18153C272 (9)

Text

ATTACHMENT 1 SURRY POWER STATION PROPOSED TECHNICAL SPECIFICATION FOR THE MAIN CONTROL ROOM AND EMERGENCY SWITCHGEAR ROOM AIR HANDLING UNITS r---,;,-n-07-1-:i:::::-::.:0*069* 900626 ~

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e e TS 3.23-1 3.23 MAIN CONTROL ROOM AND EMERGENCY SWITCHGEAR ROOM VENTILATION AND AIR CONDITIONING SYSTEMS Applicability Applies to the main control room (MCR) and emergency switchgear room (ESGR) air conditioning system and emergency ventilation system.

Objective To specify requirements to ensure the proper function of the main control and emergency switchgear room air conditioning system and emergency ventilation system.

Specification A.

Both trains of the main control and emergency switchgear rooms' emergency ventilation system shall be operable whenever either unit is above cold shutdown.

B.

With one train of the main control and emergency switchgear room emergency ventilation system inoperable for any reason, return the inoperable train to a operable status within 7 days or be in at least Hot Shutdown within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in Cold Shutdown within the following 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />.

C.

The main control and emergency switchgear room air conditioning system shall be operable as delineated in the following:

1.

Chiller Refrigeration Units

a.

Chillers 1-VS-E-4A, 4B, and 4C must be operable whenever either unit is above Cold Shutdown.

b.

If one chiller becomes inoperable, return the inoperable chiller to operable status within seven (7) days or bring both units to Hot Shutdown within the next six (6) hours and be in Cold Shutdown within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.

e TS 3.23-2

2.

Air Handling Units (AHU)

a.

Unit 1 air handling units, 1-VS-AC-1, 1-VS-AC-2, 1-VS-AC-6, and 1-VS-AC-7, must be operable whenever Unit 1 is above Cold Shutdown.

1.

If one Unit 1 AHU becomes inoperable, return the inoperable AHU to operable status within seven (7) days or bring Unit 1 to Hot Shutdown within the next six (6) hours and be in Cold Shutdown within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.

b.

Unit 2 air handling units, 2-VS-AC-8, 2-VS-AC-9, 2-VS-AC-6, and 2-VS-AC-7 must be operable whenever Unit 2 is above Cold Shutdown.

1.

If one Unit 2 MCR AHU becomes inoperable, return the inoperable AHU to operable status within seven (7) days or bring Unit 2 to Hot Shutdown within the next six (6) hours and be in Cold Shutdown within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.

• 2.

If one Unit 2 ESGR AHU becomes inoperable, bring Unit 2 to Hot Shutdown within the next six (6) hours and be in Cold Shutdown within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.

• c.

Unit 2 ESGR AHU drive motors, 2-VS-FM0-6A, 2-VS-FM0-6B, 2-VS-FM0-7 A, and 2-VS-FM0-7B must be operable whenever Unit 2 is above Cold Shutdown.

This interim specification is necessary until the air conditioning system modifications scheduled for 1991 are completed.

Following completion of the permanent modifications, a revised air conditioning system specification will be submitted.

e TS 3.23-3

1.

If a Unit 2 ESGR AHU drive motor becomes inoperable, return the inoperable drive motor to operable status within seven (7) days or bring Unit 2 to Hot Shutdown within six (6) hours and be in Cold Shutdown within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.

When the supply of compressed bottled air is depleted, the main control room and emergency switchgear room emergency ventilation system is manually started to continue to maintain the control room pressure at the design positive pressure so that leakage is outleakage. One train of the main control room emergency ventilation consists of one fan powered from an independent emergency power source.

The main control and emergency switchgear room emergency ventilation system is designed to filter the intake air to the control room pressure envelope, which consists of the control room, relay rooms, and emergency switchgear rooms during a LOCA.

High efficiency particulate air (HEPA) filters are installed before the charcoal adsorbers to prevent clogging of the iodine adsorbers. The charcoal adsorbers are installed to reduce the potential intake of radio-iodine to the charcoal room. The in-place test results should indicate a system leaktightness of less than 1 percent bypass leakage for the charcoal adsorbers and a HEPA efficiency of at least 99.5 percent removal of DOP particulates. The laboratory carbon sample test results should indicate a radioactive methyl iodide removal efficiency of at least 95 percent for expected accident conditions. The control room dose calculations assume only 90 percent iodine removal efficiency for the air passing through the charcoal filters. Therefore, if the efficiencies of the HEPA filters and charcoal adsorbers are as specified, at the temperatures, flow rates and velocities within the design values of the system, the resulting doses will be less than the allowable levels stated in Criterion 19 of the General Design Criteria for Nuclear Power Plants, Appendix A to 10 CFR Part 50.

e TS 3.23-4 If the system is found to be inoperable, there is no immediate threat to the control room, and reactor operation may continue for a limited period of time while repairs are being made.

If the system cannot be repaired within the specified time, procedures are initiated to establish conditions for which the filter system is not required.

The Main Control Room and Emergency Switchgear Room Air Conditioning System cools. the control room, the control room annex, and the Units 1 and 2 emergency switchgear and relay rooms.

The air conditioning system includes three chillers (1-VS-E-4A, 48, and 4C) and eight air handling units (1-VS-AC-1, 2, 6, and 7 and 2-VS-AC-6, 7, 8, and 9).

Interim modifications were completed on the MCR and ESGR Air Conditioning System to address interim failure and increased cooling requirements for the ESGRs.

The interim modifications included installation of redundant drive motors and power supplies to the Units 1 and 2 ESGR AHUs ~rnd a redundant power supply to the 1-VS-E-48 chiller. Permanent modifications will include replacement of the CR and ESGR AHUs and installation of an additional chiller to supplement the existing chillers. The new higher capacity AHUs and additional chiller will restore the redundancy of the original system design.

The Unit 1 MCR and ESGR AHUs have been replaced in the first phase of the permanent modification. The Unit 2 MCR and ESGR AHUs will be replaced during the next Unit 2 refueling outage. As a result of the first phase modifications, the following MCR and ESGR Air Conditioning System equipment will be required to operate to maintain design temperatures under maximum heat load calculations:

1)

Two chillers

2)

One Unit 1 MCR AHU and one Unit 1 ESGR AHU

3)

One Unit 2 MCR AHU and two Unit 2 ESGR AHUs

e TS 3.23-5 Continued system operating restrictions will be imposed on the MCR and ESGR Air Conditioning System until the permanent system upgrades are completed. The basis for the interim restrictions is as follows:

Taking credible single failures into consideration requires that redundant equipment be available during operation. As such, the three chillers and the MCR and ESG R must be operable when at power operation. Further, both drive motors on each Unit 2 ESGR AHU must be operable.

In addition to the equipment restrictions above, a fire watch will be required during this interim period in both unit's ESGR and MER #3 to address Appendix R considerations.

e ATTACHMENT 2 SURRY POWER STATION e

SIGNIFICANT HAZARDS CONSIDERATION DETERMINATION

DISCUSSION OF CHANGE The Main Control Room (MCR) and Emergency Switchgear Room (ESGR) AC System was determined to be undersized due to the addition of additional heat loads since the the beginning of operation. To allow for continued plant operation, interim modifications were completed on the MCR & ESGR AC System to provide the required cooling and meet the design basis assumptions.

The modifications included: 1) adding a redundant motor on each of the four ESGR air handling units (AHU); 2) providing alternate power supply for the swing chiller; and, 3) incorporating interim equipment operating restrictions into the Technical. Specifications.

In order to return the system to two 100% redundant trains and provide operational flexibility, additional modifications (system upgrades) have to be made. The eight AHUs (4 per unit) are being replaced with upgraded units. When these units are installed during the respective upcoming unit outage, each train's capacity will be returned to 100%. In addition, to provide operations and maintenance flexibility, an additional safety related 100% chiller will be installed in the turbine building.

Installation of this chiller will allow planned maintenance of the existing three 50%

chillers to be performed without entering a Limiting Condition of Operation. The new chiller will also provide for Appendix R separation.

We are proposing a staggered implementation of the necessary modifications. During the Unit 1 refueling outage, the Unit 1 AHUs will be replaced.

During the Unit 2 refueling outage, the Unit 2 AHUs will be replaced and the chilled water connections will be made to support the addition of the fourth chiller. After the eight AHUs (4 per unit) are replaced by the end of the Unit 2 refueling outage, the MCR & ESGR air conditioning system will be restored to two 100% redundant trains. Later in 1991, the additional chiller will be installed as non-outage work.

Subsequently, this chiller would be provided with a safety related enclosure. After completion of each phase *of the modification, a Technical Specification change will be necessary to reflect the current condition of the MCR & ESGR AC system.

This proposed Technical Specification change provides the necessary operation restrictions and action statements for the interim operation condition. This condition will exist until the Spring 1991 Unit 2 refueling outage. The Technical Specification removes the 6 hour6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> action statement for the Unit 1 ESGR AHUs and the 7 day action statement for the redundant motors on the Unit 1 ESGR AHUs. We are requesting that the Technical Specification become effective when the Unit 1 AHUs are installed and operational at the end of the Unit 1 refueling outage. The interim operating restrictions for the Unit 2 AHUs and the chillers remain intact until each phase of the modifications (system upgrades) are complete and the appropriate Technical Specification changes submitted.

e 10 CFR 50.92 SIGNIFICANT HAZARDS CONSIDERATION REVIEW Virginia Electric and Power Company has reviewed the proposed Technical Specification change against the criteria of 1 O CFR 50.92 and has concluded that the interim modification and the Technical Specification change as proposed does not pose a significant hazards consideration. Specifically, operation of the Surry Power Station in accordance with the proposed change will not:

1.

Involve a significant increase in the probability of occurrence or consequences of an accident previously evaluated. Replacement of the Air Handling Units restores the Unit 1 portion of the Main Control Room and Emergency Switchgear Room AC system to the original design. There is no impact on the probability or consequences of any previously evaluated accident.

2. Create the possibility of a new or different kind of accident from any accident previously evaluated. The modification returns the Air Handling Units (AHU) to the original design. Therefore the interim operating restrictions are no longer necessary and removal of those restrictions does not create a new or different accident from those previously evaluated.

3.

Involve a significant reduction in a margin of safety. The larger capacity AHUs restore the Unit 1 Portion of the Main Control Room and Emergency Switchgear Room AC system to the original design condition.

Therefore, eliminating the interim operating restrictions on the Unit 1 AHUs does not reduce the Margin of Safety.