LR-N11-0372, Response to Request for Additional Information Dated October 25, 2011 - License Amendment Request: Add Action for Two Inoperable Control Room Air Conditioning Subsystems
| ML113530205 | |
| Person / Time | |
|---|---|
| Site: | Quad Cities  |
| Issue date: | 12/16/2011 |
| From: | Jamila Perry Public Service Enterprise Group |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| LR-N11-0372 | |
| Download: ML113530205 (5) | |
Text
PSEG Nuclear LLC P.O. Box 236, Hancocks Bridge, NJ 08038-0236 CPSEG Nuclear LLC 10 CFR 50.90 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk
. Washington, DC 20555-0001 Hope Creek Generating Station Renewed Facility Operating License No. NPF-57 NRC Docket No. 50-354
Subject:
Response to Request for Additional Information dated October 25, 2011 - License Amendment Request: Add Action for Two Inoperable Control Room Air Conditioning Subsystems
References:
(1) LR-N11-0068, "Application for Technical Specification Change TSTF-477, Revision 3, Add Action for Two Inoperable Control Room AC Subsystems to the Technical Specifications Using Consolidated Line Item Improvement Process," dated 2/28/2011 (2) LR-N11-0250, "Response to Request for Additional Information -
License Amendment Request: Add Action for Two Inoperable Control Room Air Conditioning Subsystems In Reference 1 PSEG Nuclear LLC (PSEG) requested an amendment (H11-01) to Renewed Facility Operating License No. NPF-57 for Hope Creek Generating Station (HCGS). The proposed amendment would modify the technical specifications (TS) by adding an action statement for two inoperable control room AC subsystems to the plant specific TS.
The NRC provided PSEG a Request for Additional Information (RAI) related to the Reference 1 request, dated July 5, 2011. In Reference 2, PSEG responded on August 29, 2011, to the RAI.
On October 25, 2011, the NRC provided PSEG with a second RAI. Attachment 1 to this submittal provides the responses to the second RAI.
PSEG has determined that the information provided in this response does not alter the conclusions reached in the 10 CFR 50.92 no significant hazards determination previously submitted.
There are no commitments contained in this letter.
If you have any questions or require additional information, please do not hesitate to contact Ms.
Emily Maguire at (856)339-1023.
LR-N11-0372 Page 2 I declare under penalty of perjury that the foregoing is true and correct.
Executed on _ _ _D_E_C_1_'."_2_0_11_ _
(date)
Sincerely, 1£r:R John F. Perry 2
Site Vice President -
Attachments:
ope Creek
- 1. Response to RAI cc: Mr. W. Dean, Administrator, Region I, NRC Mr. R. Ennis, Project Manager, NRC NRC Senior Resident Inspector, Hope Creek Mr. P. Mulligan, Manager IV, NJBNE Mr. L. Marabella, Corporate Commitment Tracking Coordinator Mr. K. Yearwood, Hope Creek Commitment Tracking Coordinator LR-N11-0372
- 1. PSEGs response to request for additional information (RAI) question 3 in the supplement dated August 29, 2011, stated, in part, that:
HVAC system inoperability may result in CREF inoperability. In the event of a A(B)-P-400 chilled water pump trip, the A(B)-K-400 chiller will trip, which will trip the A(B)-VH403 and the CREF system. Due to these interlocks, if the Control Room AC subcomponents trip, then CREF will also be inoperable. However, the CREF function is to maintain habitability within the Control Room Envelope via filtration. The CREF trains are independent of the Control Room AC system and would be functional for conditions that do not result in a trip of the Control Room AC system, for example reduced chiller heat removal capability.
The use of the word independent in the above statement is not clear. If the CREF trains are independent of the Control Room AC system, why does a trip of the Control Room AC result in an inoperable CREF?
Question 1 Response:
The Control Room Supply (CRS) unit and CREF system can be placed in-service without an in-service Control Room AC train. All fans may be started without an interlock from the chilled water pump or chiller. However, in normal alignment with the Control Room AC system operating to supply cooling to the CRS unit, a trip of the Control Room AC chilled water pump does send a trip signal to the CRS unit, which results in a trip of the operating CREF fan. This is a one-second momentary trip signal. The CRS unit and CREF may be re-started following this trip, without operating chilled water pump or chiller subcomponents of the Control Room AC system. Current technical specifications require declaring the CREF inoperable when the Control Room AC is inoperable. This amendment request is intended to remove this current inter-dependency and allow for operability of CREF without chilled water.
- 2. Please confirm if the following statements are correct (if not, please clarify):
(a) Air exhausting from each CREF filter train (A(B)-VH400) goes to the respective Control Room Supply (CRS) unit (A(B)VH403) and then to the control room.
Question 2a Response:
Correct.
(b) Each CRS unit has a low efficiency filter, a high efficiency filter, a fan, a cooling coil (cooled by chilled water system), a heating coil and a humidifier. The cooling coil supports the control room AC function.
Question 2b Response:
Correct.
(c) In order for CREF to perform its design basis function, the fan portion of the CRS needs to be operating. CREF system functionality is not dependent on the control room AC temperature control function.
Question 2c Response:
Correct.
1 of 3 LR-N11-0372 (d) Due to the electrical interlocks in the current plant design, if a control room AC subcomponent trips, the associated CRS unit will trip thus also making the associated CREF train inoperable (i.e., solely because the CRS fan is inoperable).
Question 2d Response:
Correct. Current technical specifications require declaring CREF inoperable when the Control Room AC is inoperable. This amendment request is intended to remove this current inter-dependency and allow for operability of CREF without chilled water. If operating, a trip of the control room chilled water pump will trip the CRS unit. However, the CRS unit, and CREF, may be started without a control room chilled water pump being in-service.
(e) If the proposed amendment is approved, the licensee may make a subsequent plant modification to remove the interlocks discussed in (d). This would enable control room AC to be inoperable without automatically tripping the CRS unit including its fan. As such, the associated CREF train would no longer need to be declared inoperable solely due to control room AC system inoperability.
Question 2e Response:
Correct. The proposed modification would eliminate the trip of the CRS unit following a trip of an operating chilled water pump. Due to the current ability to place CREF in-service without a chilled water pump, the amendment would support CREF operability in the current plant configuration.
(f) If the proposed amendment is approved and the licensee does not perform the plant modification discussed in (e) (i.e., interlocks are still in place), if a control room AC subcomponent trips, the associated CRS unit will trip thus also making the associated CREF train inoperable (i.e., solely because the CRS fan is inoperable).
Question 2f Response:
If the proposed amendment is approved, CREF will remain operable without Control Room AC, provided the CRS fan is not the failed component. In the event of a chilled water pump trip, there are no start permissives that would prevent manual restart of the CRS unit and CREF.
The CRS unit and CREF would be able to be re-started, and would remain operable.
Without an available control room chilled water pump, CREF will auto initiate in the event of a LOCA or high radiation, as there are no start permissives for an operational control room chilled water pump. Start signals for the CREF unit, CRS, and CRRA fan are generated independently in the start logics.
If a control room chilled water pump were to trip following auto-initiation, the CRS unit would trip.
This would cause the CREF and CRRA fans to trip on low flow. If the standby CREF train is available, it would receive an auto-start initiation signal. If the standby CREF train is unavailable, the CREF, CRRA, and CRS fans may be manually restarted.
(g) If the proposed amendment is approved (and before the plant modification is done), if both trains of the control room AC system were inoperable, then both trains of CREF would need to be declared inoperable and the plant would enter TS 3.0.3 per the CREF TS. This is no different than the current TS requirements.
2 of 3 LR-N11-0372 Question 2g Response:
If the proposed amendment is approved, CREF operability would not be dependant upon the Control Room AC System. Therefore, both trains of Control Room AC being inoperable would not impact CREF, and CREF would remain operable. CREF can be placed in-service without the control room chiller and chilled water pump subcomponents of the Control Room AC.
(h) The proposed amendment does not change any of the assumptions in the HCGS licensing basis analyses of design basis accident consequences.
Question 2h Response:
The control room post-LOCA dose calculation conservatively assumes that CREF is not initiated until 30 minutes after the event. In the event of the unavailability of the standby train, this is adequate time to manually start CREF if a trip of the control room chilled water pump occurs.
- 3. With an inoperable control room AC system and an inoperable CRS unit, will the control room return air (CRRA) fan and corresponding flow element be inoperable? Is the CRRA fan required to be operable in order for the CREF to be operable?
Question 3 Response:
An inoperable Control Room AC system (chiller or chilled water pump) has no impact on the Control Room Return Air (CRRA) fan and flow element, and thus it will remain operable. If the CRS is inoperable, both the CRRA and CREF fans will be inoperable.
The CRRA unit is required to be operable for the CREF to be operable. A trip of a CRRA fan has no direct trip interlocks with other equipment; however the associated CRS and CREF units will trip on low flow.
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