ML18153C882
| ML18153C882 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 01/22/1992 |
| From: | Stewart W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML18153C883 | List: |
| References | |
| 92-033, 92-33, NUDOCS 9201280180 | |
| Download: ML18153C882 (9) | |
Text
VIRGINIA ELECTRIC AND POWER COMPANY RICHMOND, VIRGINIA 23261 e
January 22, 1992 United States Nuclear Regulatory Commission Serial No.92-033 Attention: Document Control Desk NO/ETS Washington, D. C. 20555 Docket Nos. 50-280 50-281 License Nos. DPR-32 DPR-37 Gentlemen:
VIRGINIA ELECTRIC AND POWER COMPANY SURRY POWER STATION UNITS 1
- AND 2 PROPOSED TECHNICAL SPECIFICATION FOR THE MAIN CONTROL ROOM AND EMERGENCY SWITCHGEAR ROOM AIR CONDITIONING SYSTEM Pursuant to 10 CFR 50.90, the Virginia Electric and Power Company requests an amendment, in the form of a change to the Technical Specifications, for Surry Power Station Unit 2. As part of the upgrade to the Main Control Room (MCR) and Emergency Switchgear Room (ESGR) air conditioning system, both the Units 1 and 2 air handling units (AHU) have been replaced. Two additional chillers are scheduled for installation during 1992. To facilitate non-outage installation of the new chillers, chilled water connections into the existing common discharge header are required. This activity will require each train of the air conditioning system to be sequentially isolated and partially drained.
Each train of the air conditioning system consists of one AHU in the MCR and ESGR of each unit ( a total of four AHUs). Isolation of either train of air conditioning renders one of two AHUs in each cooled space in each unit inoperable. Although the remaining one AHU in each space is sufficient to individually cool the space by itself, the existing Surry Technical Specifications require a unit shutdown within six hours if a total of two or more AHUs are inoperable in the unit. Therefore, we are requesting a Technical Specification change that will allow planned entries into a seven day action statement with two AHUs inoperable (one per cooled space), to permit installation of chilled water connections for the additional chillers to be installed in 1992. The proposed changes are included in .
- The installation of chilled water connections is presently proposed for the upcoming Unit 1 refueling outage. By completing the work during the Unit 1 outage, application of the proposed specification would be limited to entri~s into the associated action statement for Unit 2 only. During the planned action statement entries, the redundant AHUs in each space will be maintained operable or the remedial actions required by Technical Specifications will be followed.
9201280180 920122 PDR ADOCK 05000280 P PDR 1100/
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~ Thi"s request has been reviewed and approved by the Station Nuclear Safety and Operating Committee and the Management Safety Review Committee. It has been determined that the proposed changes do not involve an unreviewed safety question as defined in 10 CFR 50.59 or a significant hazards consideration as defined in 10 CFR 50.92. The basis for our no significant hazards consideration determination is included in Attachment 1.
Very truly yours, fdr 9-P~~
W. L. Stewart Senior Vice President - Nuclear Attachments cc: U. S. Nuclear Regulatory Commission Region II 101 Marietta Street, N. W.
Suite 2900 Atlanta, Georgia 30323 Mr. M. W.Branch NRC Senior Resident Inspector Surry Power Station Commissioner Department of Health Room 400 109 Governor Street Richmond, Virginia 23219
e COMMONWEALTH OF VIRGINIA )
)
COUNTY OF HENRICO )
The foregoing document was acknowledged before me, in and for the County and Commonwealth aforesaid, today by J. P. O'Hanlon who is Vice President - Nuclear Services, for W. L. Stewart who is Senior Vice President - Nuclear, of Virginia Electric and Power Company. He is duly authorized to execute and file the foregoing document in behalf of that Company, and the statements in the document are true to the best of his knowledge and belief.
Acknowledged before me this zz 1,_d day of My Commission Expires: c/JJci, 31
~ - L/_ JI *-
4~
Notary Public
e ATTACHMENT 1 SURRY POWER STATION DISCUSSION OF PROPOSED TECHNICAL SPECIFICATION CHANGE AND SIGNIFICANT HAZARDS CONSIDERATION DETERMINATION MAIN CONTROL ROOM AND EMERGENCY SWITCHGEAR ROOM AIR HANDLING UNITS
DISCUSSION OF CHANGE INTRODUCTION The Main Control Room (MCR) and Emergency Switchgear Room (ESGR) Air Conditioning (AC) System is being modified to provide additional chilled water capacity for operational flexibility consistent with the original plant design. The proposed Technical Specification change to support the installation of chilled water connections is necessary to facilitate the non-outage installation of two new fifty percent capacity chillers.
BACKGROUND The MCR and ESGR AC System was determined to be undersized due to the unrecognized incremental addition of heat loads in these areas over an extended period of time. To allow for continued plant operation, interim modifications were completed on the MCR and ESGR AC System in 1989. These interim modifications ensured that required design basis assumptions for cooling continued to be met.
During subsequent outages, Units 1 and 2 AHUs were replaced with larger capacity units. After these replacements, the AHU portion of the MCR and ESGR AC System was restored to two 100% redundant trains. In order to return the entire system to two 100% redundant trains and provide operational flexibility, additional chiller capacity (system upgrade) is required.
Installation of additional chiller capacity is scheduled as non-outage work in 1992. In order to install chilled water connections for the new chillers, each train of MCR and ESGR AC System must be sequentially isolated and partially drained. This will require removing two AHUs per Unit (one per cooled space) and one of the three 50%
capacity chillers from service for approximately seven days. Removing one chiller from service for seven days is permitted by the existing Technical Specifications.
However, removing two AHUs per Unit (one per cooled space) is currently not permitted by Technical Specifications. With the presently upgraded AHU configuration, the existing seven day action statement can be expanded to allow an inoperable AHU in each cooled space without adversely impacting plant safety.
e TECHNICAL SPECIFICATION The AHUs in each cooled space have been restored to the original design capability of two redundant 100% capacity units. Therefore, each cooled space could have an AHU inoperable and still meet the design base ventilation (cooling) requirements.
However, the existing Technical Specification, which is unit specific and not ventilation area specific, provides a seven day action statement with any one of the four unit specific AHUs inoperable. This proposed Technical Specification change will allow planned entries into the seven day action statement of TS 3.23.C.2 with one inoperable AHU in the MCR and one inoperable AHU in the ESGR in each unit from the same chilled water train to permit installation of chilled water connections for the two additional 50% chillers to be installed in 1992. It is intended to complete the modifications within two planned entries into the action statement during the upcoming Unit 1 refueling outage. Performing the modification during the Unit 1 outage will eliminate entering an action statement on that unit. However, the footnote is not limited to two entries and if difficulties are experienced during the modification, the action statement can be exited and subsequently reentered to complete the chilled water connections in that train of chilled water.
The proposed Technical Specification change, in the form of a footnote, establishes a seven day action statement for planned entries and will expire on June 30, 1992. The footnote reads as follows:
"The MCR and ESGR Air Conditioning System upgrade project includes the installation of two additional chillers. It is necessary to remove each train of chilled water from service for seven days to complete the installation of the chilled water connections for the additional chillers. The modifications will require planned entries into Action Statement 3.23.C. 2 with one inoperable AHU in the MCR and one inoperable AHU in the ESGR of each unit to complete. This modified action statement will only be used for the installation of the chilled water connections in the MRC and ESGR Air Conditioning System and will expire June 30, 1992."
SAFETY SIGNIFICANCE The ability of an AHU to perform its design function is not dependent on the availability of AHUs for the other spaces. Removing an AHU from service in one space does not impact the ability of the system to cool the other space, since there are redundant
100% capacity AH Us in each space. Therefore, establishing a seven day action statement that allows an AHU in each cooled space to be inoperable at the same time does not create an unreviewed safety question. The probability of occurrence of an accident and the consequences of an accident will not be affected by the operation of the air conditioning system in this manner. During entry into the action statement ventilation capacity requirements are maintained. The air conditioning system is not being operated any differently. Therefore, no new accident precursors are being generated. With the redundancy and capacity of the upgraded AHU configuration returned to original design, the margin of safety is not reduced during entry into this action statement with one AHU inoperable in each discrete ventilation area.
10 CFR 50.92 SIGNIFICANT HAZARDS CONSIDERATION REVIEW Virginia Electric and Power Company has reviewed the proposed Technical Specification change against the criteria of 10 CFR 50.92 and has concluded that the Technical Specification change as proposed does not pose a significant hazards consideration. The Air Handling Units (AHUs) in each cooled space have been restored to the original design of two redundant 100% capacity units. However, the existing Technical Specification requires entry into a seven day action statement when any one of the four AHUs becomes inoperable in either unit. This proposed Technical Specification change will allow planned entries into a seven day action statement, with two AHUs inoperable per unit (one per cooled space) to facilitate installation of chilled water connections for the two additional chillers to be installed in 1992. 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 Units 1 and 2 Air Handling Units with larger capacity AHUs has restored Units 1 and 2 Main Control Room (MCR) and Emergency Switchgear Room (ESGR) AC system to its original design capability of providing two 100%
redundant trains of cooling in each space. Because the AHUs in each space have been returned to original design (redundant 100% capacity),
plant operation with two inoperable AHUs per unit, one in each space for the duration of the action statement does not increase in 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. Operation of the air conditioning system in this manner does not generate any new accident precursors because design base ventilation capability is maintained with operation of one AHU per cooled space per unit. Therefore, operation with an inoperable AHU in the MCR and ESGR for each unit for seven days to complete system modifications 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 Units 1 and 2 AHUs have restored the Main Control Room and Emergency Switchgear Room AC system to original design capabilities. The proposed entries into the seven day action statement with one AHU inoperable per cooled space on each unit do not reduce the margin of safety since the remaining operable AHU per cooled space is capable of meeting design base ventilation requirements. Therefore, operation with one inoperable AHU in the MCR and ESGR for each unit for the duration of the existing seven day action statement does not reduce the margin of safety.