DCL-08-093, Response to NRC Request for Additional Information Regarding License Amendment Request 08-02, Revision to Technical Specifications 3.7.5, 'Auxiliary Feedwater System,' and 3.7.6, 'Condensate Storage Tank and Fire Water..
| ML083260564 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 11/06/2008 |
| From: | Becker J Pacific Gas & Electric Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| DCL-08-093 | |
| Download: ML083260564 (8) | |
Text
PacificGas and Electric Company' Diablo Canyon Power Plant P.0. Box 56 Avila Beach, CA 93424 November 6, 2008 PG&E Letter DCL-08-093 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Docket No. 50-275, OL-DPR-80 Docket No. 50-323, OL-DPR-82 Diablo Canyon Units 1 and 2 Response to NRC Request for Additional Information Regardinq License Amendment Request 08-02, "Revision to Technical Specifications 3.7.5, 'Auxiliary Feedwater System,' and 3.7.6, 'Condensate Storage Tank and Fire Water Storage Tank"'
References:
- 1. PG&E Letter DCL-08-023, "License Amendment Request 08-02, Revision to Technical Specifications 3.7.5, 'Auxiliary Feedwater System,' and 3.7.6, 'Condensate Storage Tank and Fire Water Storage Tank,"' dated April 3, 2008
- 2. PG&E Letter DCL-08-051, "Supplement to License Amendment Request 08-02, 'Revision to Technical Specifications 3.7.5,
'Auxiliary Feedwater System,' and 3.7.6, 'Condensate Storage Tank and Fire Water Storage Tank,"' dated June 20, 2008
- 3. PG&E Letter DCL-08-081, "Response to NRC Request for Additional Information Regarding License Amendment Request 08-02, 'Revision to Technical Specifications 3.7.5, 'Auxiliary Feedwater System,' and 3.7.6, 'Condensate Storage Tank and Fire Water Storage Tank,"' dated October 1, 2008
Dear Commissioners and Staff:
In Reference 1, Pacific Gas and Electric Company (PG&E) submitted License Amendment Request (LAR) 08-02, which proposes to revise Technical Specification (TS) 3.7.5, "Auxiliary Feedwater System," to remove Surveillance Requirement 3.7.5.6, and revise TS 3.7.6, "Condensate Storage Tank (CST) and Fire Water Storage Tank (FWST)," to remove the FWST level requirements, revise the CST level requirements, and revise TS 3.7.6 to be consistent with the NUREG-1431 Standard TS. In References 2 and 3, PG&E submitted a supplement to LAR 08-02 and a response to a request for additional information to LAR 08-02, respectively.
A member of the STARS (Strategic Teaming and Resource Sharing) Alliance Callaway
- Comanche Peak
- Diablo Canyon
- Palo Verde
- South Texas Project
- Wolf Creek
Document Control Desk PG&E Letter DCL-08-093 November 6, 2008 Page2 On September 21, 2008, the NRC staff requested additional information required to complete the review of LAR 08-02. PG&E's responses to the staff's questions are provided in the Enclosure.
This information does not affect the results of the technical evaluation or the no significant hazards consideration determination previously transmitted in Reference 1.
PG&E makes no regulatory commitments (as defined by NEI 99-04) in this letter.
This letter includes no revisions to existing regulatory commitments.
If you have any questions, or require additional information, please contact Stan Ketelsen at (805) 545-4720.
I state under penalty of perjury that the foregoing is true and correct.
Executed on November 6, 2008.
SiT crely, James R. Becker \
Site Vice President kjse/4328 50043292 Enclosure cc: Gary W. Butner, California Department of Public Health Elmo E. Collins, NRC Region IV Michael S. Peck, NRC, Senior Resident Inspector Diablo Distribution cc/enc: Alan B. Wang, NRC Project Manager A member of the STARS (Strategic Teaming and Resource Sharing) Alliance Callaway
- Comanche Peak
- Diablo Canyon
- Palo Verde
- South Texas Project ° Wolf Creek
Enclosure PG&E Letter DCL-08-093 Pacific Gas and Electric Company (PG&E) Response to NRC Request for Additional Information Regarding License Amendment Request (LAR) 08-02, "Revision to Technical Specifications 3.7.5, 'Auxiliary Feedwater System,'
and 3.7.6, 'Condensate Storage Tank and Fire Water Storage Tank"'
NRC Question 1:
On page 4 of the license amendment request, the condensate storage tank (CST) is described as having "a floating roof to minimize oxygen absorption by the stored water." This implies that the roof of the tank would follow the water level as it decreases. However, the plenums extend into the inner volume of the tank and might block the path of the floating roof if water level drops below the tops of the plenums.
In accordance with 10 CFR 50.59, the licensee can make changes to the facility; however, that change should not create a possibility for a malfunction of an structure, system and component (SSC) important to safety with a different result than any previously evaluated.
Describe how the modifications to the CST impact the function of the floating roof, and verify that no new failure mechanisms are created that affect the ability of the CST to provide its safety-related function.
PG&E Response:
The floating roof for the Diablo Canyon Power Plant (DCPP) Unit 2 CST was replaced during the Unit 2 Fourteenth Refueling Outage in the spring of 2008 when the new CST inner plenums were added. The floating roof for the DCPP Unit 1 CST will be replaced and new CST inner plenums will be added during the Unit 1 Fifteenth Refueling Outage beginning in January 2009. The floating roof is Design Class II, non-safety related. However, the CST was evaluated for seismic impact with the floating roof in place.
The new CST floating roof is designed with cutouts to clear the new inner plenums.
The new floating roof is also equipped with Buna-N seals around its perimeter, including the clearance cutouts around the new inner plenums to minimize absorption of oxygen into the CST water. The floating roof is restricted from rotating in the horizontal direction by two anti-rotating guide wire assemblies. With the new floating roof having cutouts and anti-rotating guides, the new inner plenums will not block the pathway of the floating roof if water level drops below the top of the plenums since the roof will clear the plenums during its movement up and down within the CST. Even if the floating roof were to rotate and to be blocked by the CST plenums during draining of the CST, the flow of water from the CST to the suction of the auxiliary feedwater pumps would not be impacted. This is because the nozzle to the auxiliary feedwater pumps is located approximately 2 feet from the 1
Enclosure PG&E Letter DCL-08-093 bottom of the CST and will not be blocked by the floating roof. Also the absorption of oxygen into the CST water during this period would be negligible: Therefore, the replacement of the CST floating roof and the addition of inner plenums to the CST does not create a new failure mechanism that could affect the ability of the CST to perform its safety-related function. Refer to drawings 663217-321 and 663217-323 in this Enclosure for details of the floating roof design and cutouts around the plenums.
NRC Question 2: to the license amendment supplemental information (Westinghouse Letter PGE-08-45)states that the "assumedlevel restorationwas reduced from no load programmedlevel to the Narrow Range lower level tap," in order to reduce the required CST inventory.
10 CFR 50.34 requires the licensee comply with the StandardReview Plan, NUREG 0800, or provide an acceptable alternative. NUREG 0800, Section 13.5.2.1, Operating and Emergency Operating Procedures,states that the Emergency Operating Procedures(EOPs) will be based upon acceptable technical guidelines derived from approved analyses of transientsand accidents.
Describe how this change in the restorationlevel is reflected in the plant operating procedures for loss-of-offsite-power with a naturalcirculationcooldown.
Verify that any difference in restorationlevel assumed in the calculation and the plant operatingprocedures will not have adverse effects on the ability to prevent forming voids in the reactorvessel while.cooling the RCS.
PG&E Response:
As stated in Westinghouse Letter PGE-08-45 contained in Enclosure 4*to PG&E-Letter DCL-08-051, "Supplement to License Amendment Request 08-02, 'Revision to Technical Specifications 3.7.5, 'Auxiliary Feedwater System,' and 3.7.6,
'Condensate Storage Tank and Fire Water Storage Tank,"' dated June 20, 2008, the CST minimum storage usable volume calculation assumed steam generator (SG) level restoration to the SG narrow range lower level tap, which was a reduction from the no load programmed level (normal operating SG level) assumed in the previous analysis. This results in a reduction in the required CST inventory of approximately 20,000 gallons. The CST minimum storage usable volume calculation is the analytical basis for the proposed Technical Specification (TS) 3.7.6 water volume of greater than or equal to 200,000 gallons for Unit 1 and greater than or'equal to 166,000 gallons for Unit 2. The volume utilized for SG refilling is not required for safe operation of the plant. In order to bound the SG level assumption in the CST minimum storage usable volume calculation, the EOP for natural circulation cooldown needs to maintain SG level above the narrow range lower level tap in order to ensure the SG heat transfer assumed in the calculation is provided and that 2
Enclosure PG&E Letter DCL-08-093 the SG level is known accurately by maintaining the level within the narrow range band.
Emergency Operating Procedure (EOP) E-0.2, "Natural Circulation Cooldown,"
provides actions to perform a natural circulation reactor coolant system (RCS) cooldown and depressurization to cold shutdown, with no accident in progress, under requirements that will preclude any reactor vessel upper head void formation and flow stagnation in an inactive loop(s). The E-0.2 procedure includes actions to cooldown the RCS to residual heat removal system (RHRS) entry conditions, and to continue RCS cooldown to cold shutdown conditions using the RHRS.
For operation with the replacement SGs during cooldown to RHRS entry conditions, EOP E-0.2 specifies to maintain SG narrow range level between 20 percent and 65 percent, which is conservatively above the zero percent SG narrow range level assumed in the CST minimum storage usable volume calculation. The normal indicated operating water level for the replacement SGs is 65 percent narrow range level. Procedure EOP E-0.2 could be revised to maintain the SG narrow range level at the minimum level that ensures zero percent SG narrow range level is maintained (including instrument uncertainties) and that the level assumed in the CST minimum storage usable volume calculation is bounded. However, the EOP E-0.2 requirement to maintain SG narrow range level between 20 percent and 65 percent is not being revised due to the change in the restoration level assumption in the CST minimum storage usable volume calculation. The EOP E-0.2 requirement to maintain SG narrow range level between 20 percent and 65 percent conservatively bounds the restoration level assumption in the CST minimum storage usable volume calculation and provides operational flexibility to maintain the SG narrow range level over a range that includes up to the normal SG operating water level.
The difference in the SG restoration level assumed in the EOP E-0.2 procedure and the CST minimum storage usable volume calculation will not have an adverse effect on the ability to prevent forming voids in the reactor vessel while cooling the RCS because the EOP E-0.2 requirement to maintain SG narrow range level between 20 percent and 65 percent conservatively bounds the restoration level assumption in the CST minimum storage usable volume calculation.
The CST contains adequate volume to support the EOP E-0.2 requirement to maintain SG narrow range level between 20 percent and 65 percent. Since the proposed TS 3.7.6 volume for DCPP Unit 1 of 200,000 usable gallons is less than the 222,600 usable gallons provided by the upgraded CST at the level of the top of the installed plenums, a safety grade CST volume of approximately 22,600 gallons is available to maintain SG narrow range level. This exceeds the approximately 20,000 gallons required to fill the four steam generators from the SG narrow range lower level tap level to the normal operating SG level (65 percent narrow range span). For DCPP Unit 2, a greater safety grade CST volume is available since the proposed TS 3.7.6 volume for DCPP Unit 2 of 166,000 gallons is less than the proposed DCPP Unit 1 volume of 200,000 usable gallons. Also, there is an 3
Enclosure PG&E Letter DCL-08-093 additional 18,000 gallons of non-safety grade water that is normally available since the CST level is maintained by procedure above 60.8 percent indicated level, which is24 inches above the top of the plenums.
NRC Question 3:
The license amendment request would fully remove the fire water storage tank (FWST) requirementsfrom the Technical Specifications (TS). Afterwards, the licensee intends to remove the FWST from service for approximately 90 days.
Confirm that there is no credit for the FWST that would necessitate FWST inclusion in TS, including any license conditions, commitments, or credit in design basis.
PG&E Response:
With implementation of the upgrade of the DCPP CSTs to replace all condensate water currently being credited to be supplied from the FWST, there is no credit for the FWST function in the DCPP design basis that necessitates inclusion of the FWST in the TS, including in any license conditions or commitments.
The FWST was originally contained in the TS 3.7.9.1 as part of the Fire Suppression Water System. The TS 3.7.9.1 "Fire Suppression Water System," requirements were removed from the TS by Amendment No. 75 to Facility Operating License No.
DPR-80 and Amendment 74 to Facility Operating License No. DPR-82, for DCPP Units 1 and 2, respectively, d~ated January 13, 1993. PG&E requested removal of the TS 3.7.9.1 Fire Suppression Water System requirements in PG&E Letter DCL-90-271, "License Amendment Request 90-11, Revision of Fire Protection License Conditions, Relocation of Fire Protection Technical Specifications, and Clarification of AFW Water Sources," dated November 15, 1990. The basis for the requested removal of the TS 3.7.9.1 Fire Suppression Water System requirements to plant procedures and the Final Safety Analysis Report was Generic Letter 86-10, "Implementation of Fire Protection Requirements" and GL 88-12, "Removal of Fire Protection Requirements from Technical Specifications." The FWST requirements originally contained in TS 3.7.9.1 are now contained in the licensee controlled document Equipment Control Guideline (ECG) 18.1, "Fire Suppression Systems/Fire Suppression Water Systems." DCPP Unit 1 License DPR-80 sections 2.C.5 and 2.1 and DCPP Unit 2 License DPR-82 sections 2.C.4 and 2.1 contain fire related license conditions; however, these conditions do not include specific requirements for the FWST. The DCPP procedure commitment database does not contain any FWST related commitments that require a FWST TS requirement.
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