ML073380394
| ML073380394 | |
| Person / Time | |
|---|---|
| Site: | Three Mile Island  |
| Issue date: | 11/29/2007 |
| From: | Cowan P AmerGen Energy Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 5928-07-20225, TAC MD5963 | |
| Download: ML073380394 (8) | |
Text
AmerGen Energy Company, LLC www.exeloncorp.com AmerGen. An Exel1n Company 20o Exelon Way Kennett Square, PA 19348 10 CFR 50.90 November 29, 2007 5928-07-20225 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 Three Mile Island, Unit 1 (TMI Unit 1)
Facility Operating License No. DPR-50 NRC Docket No. 50-289
Subject:
Response To Request For Additional Information - Technical Specification Change Request No. 337: Reactor Building Emergency Sump pH Control System Buffer Change (TAC No. MD5963)
References:
(1) USNRC letter to AmerGen Energy Company, LLC, dated November 27, 2007, 'Three Mile Island Nuclear Station, Unit 1 - Request for Additional Information Regarding Proposed Reactor Building Emergency Sump System Buffer Change (TAC No. MD5963)"
(2) AmerGen Energy Company, LLC letter to USNRC dated June 29, 2007 (5928-07-20097), 'Technical Specification Change Request No. 337 -
Reactor Building Emergency Sump pH Control System Buffer Change" This letter provides additional information in response to the NRC request for additional information (RAI), issued November 27, 2007 (Reference 1), regarding TMI Unit 1 Technical Specification Change Request No. 337, submitted to NRC for review on June 29, 2007 (Reference 2). The additional information is provided in Enclosure 1.
No new regulatory commitments are established by this submittal. If any additional information is needed, please contact David J. Distel at (610) 765-5517.
I declare under penalty of perjury that the foregoing is true and correct. Executed on the 2 9 th day of November, 2007.
Respectfully, Pamela B. Cowan 16.I Director - Licensing & Regulatory Affairs AmerGen Energy Company, LLC
U.S. Nuclear Regulatory Commission November 29, 2007 Page 2
Enclosure:
- 1) Response to Request for Additional Information cc: S. J. Collins, USNRC Administrator, Region I P. J. Bamford, USNRC Project Manager, TMI Unit 1 D. M. Kern, USNRC Senior Resident Inspector, TMI Unit 1 File No. 07029
ENCLOSURE 1 TMI UNIT 1 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION TECHNICAL SPECIFICATION CHANGE REQUEST No. 337 Reactor Building Emergency Sump pH Control System Buffer Change
5928-07-20225 Page 1 of 5 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION (RAI)
TMI UNIT 1 TECHNICAL SPECIFICATION CHANGE REQUEST No. 337 Reactor Building Emergency Sump pH Control System Buffer Change
- 1. NRC Question Your response to the NRC staff's question in letter dated October 19, 2007, regarding calcium sources and dissolved calcium concentration in the post-LOCA pool (Question #9) did not contain sufficient detail for the staff to complete its review. Testing has shown that TSP, in the presence of dissolved calcium, can result in rapid formation of calcium phosphate precipitates that can be detrimental to Emergency Core Cooling System operability. Licensees who use TSP need to ensure that their plant specific calcium loading will not create a precipitate load that challenges the operability of their strainers.
Although calcium silicate insulation is the most significant source of calcium in most containments, there are many other sources that must be considered. Calcium may be dissolved from other insulation materials such as mineral wool, marinate board, and other micro-porous insulation materials. Calcium leached from concrete can contribute to chemical effects, especially in containments with large areas of uncoated concrete, or containments in which concrete may be eroded by direct jet impingement. Because of the concerns listed above, the staff requested in letter dated October 4, 2007, that TMI provide the potential calcium sources and provide the dissolved calcium level following a LOCA.
The staff specifically requests a response to the following information from the previous Request for Additional Information question #9 in order to complete our review of this amendment request:
A.) Provide a complete list of potential calcium sources in the TMI-1 containment, including their expected contribution to calcium loading and the basis for the estimated contribution from each source.
Response
The only sources that have been determined to contribute to the calcium loading are concrete, fiberglass and Thermo-Lag fiber. TMI Unit 1 has no calcium silicate insulation and is considered a low calcium plant, similar to Integrated Chemical Effects Testing (ICET) Project Test #2 with the proposed buffer change. The table below provides the list of materials and quantities evaluated. The quantities were taken from calculation ALION-REP-EXEL-2737-13, Revision 1, which is being prepared to support the TMI Unit 1 response to NRC Generic Letter (GL) 2004-02. This analysis is currently being finalized and the results are not expected to change. The basis for the estimated contribution to the calcium loading is the corrosion model provided in WCAP-1 6530.
5928-07-20225 Page 2 of 5 Material Class Material Amount Reference Metallic Aluminum Aluminum Submerged 2361.8 ALION-REP-EXEL-(ft2) 2737-13, Rev. 1 Aluminum 2500 ALION-REP-EXEL-Unsubmerged ft2) 2737-13, Rev. 1 E-Glass Nukon (ft') 682 ALION-REP-EXEL-2737-13, Rev. 1 Latent fiber (ftd) 18.75 ALION-REP-EXEL-2737-13, Rev. 1 Thermolag Fiber (ftW) 0.25 ALION-REP-EXEL-2737-13, Rev. 1 Concrete Concrete exposed and 1104 ALION-REP-EXEL-submerged (ft2) 2737-13, Rev. 1 B.) Provide the calculated dissolved calcium level in the post-LOCA sump pool.
Response
Using the materials described above, the dissolved calcium level in the post-LOCA sump pool is approximately 10 ppm per the WCAP-1 6530. In addition, TMI Unit 1 has performed independent leaching studies in an integrated environment, as part of the alternate 30-day chemical effects testing, and found the calcium levels to be consistent with ICET Project Test #2 and the WCAP-16530, which is approximately 10 ppm.
C.) Provide a comparison of post-LOCA precipitate loading under existing buffer and proposed buffer at the maximum projected pH value (8) for the pool. This may be done using the WCAP-16530 model or other means.
Response
The following comparison was developed using WCAP-16530 with nominal plant parameters (pool volume, temperatures, etc.). A NaOH model with a pH value (8) was not used because the current design basis allows a final Reactor Building sump pH as high as 9.07 (Reference calculation C-1 101-210-5340-007, "LOCA SUMP/Spray pH with Single failure"). The NaOH model pH is 9.1 and TSP model pH is 8.0. Both buffers and associated models consider a short time at a low pH due to spray with the TSP and blowdown with the NaOH. These comparisons are performed for the maximum fiber load case and illustrate the relative differences in projected precipitate formation. Fiberglass and Thermo-lag fiber are covered in the category of "E-glass" in the WCAP-1 6530. The benefits provided by the change to TSP (i.e., lowering of the pH and reduction in aluminum precipitate (183.5 kg)) significantly outweigh the slight addition of calcium phosphate (42.55 kg).
The TSP buffer tabulation is based on the calculation ALION-REP-EXEL-2737-13, Revision 1, prepared for TMI Unit 1. The NaOH buffer tabulation was developed for comparison purposes and is not part of the formal calculation supporting this evaluation.
5928-07-20225 Page 3 of 5 NaOH Buffer - Precipitate (kg) pH 9.1 Ca 3 (PO 4)2 NaAISi30 8 AIOOH Metallic Aluminum Submerged 0.00 16.61 6.71 Metallic Aluminum Not-Submerged 0.00 169.67 68.53 Calcium Silicate 0.00 0.00 0.00 E-Glass 0.00 221.17 7.05 Silica Powder 0.00 0.00 0.00 Mineral Wool 0.00 0.00 0.00 Aluminum silicate 0.00 0.00 0.00 Concrete 0.00 0.01 0.00 Interam 0.00 0.00 0.00 Total 0.00 407.46 82.29 Corililbuflons to Reipftates by Wealln 450.00 400.00 350.00 0 Irteram 0 Cocnzite SE rdunsiikcate 0MWaal WW
'250.00 0 Slica Pmder
- E-Gass o clduniiud~kae
- Meaic~ Aurmrun No~t-S&bm~gd 1500.0
- Walk Alurnm rubrrirgqd 0.00 COP0R4)2 NAS0 JC
5928-07-20225 Page 4 of 5 TSP Buffer - Precipitate(kg) ph 8.0 Ca 3 (P04)2 NaAISi3O 8 AIOOH Metallic Aluminum Submerged 0.00 22.33 4.10 Metallic Aluminum Not-Submerged 0.00 102.10 18.75 Calcium Silicate 0.00 0.00 0.00 E-Glass 42.53 156.06 2.90 Silica Powder 0.00 0.00 0.00 Mineral Wool 0.00 0.00 0.00 Aluminum silicate 0.00 0.00 0.00 Concrete 0.02 0.01 0.00 Interam 0.00 0.00 0.00 Total 42.55 280.50 25.75 Contributions to Precipitates by Material 300.00 250.00 0 Interam 20000 NConcrete I Aluminum silicate
- Mineral Wool U Silica Powder
- E-Glass 0 Calcium Silicate E Metallic Aluminutm Not-Submerged
- Metallic Aluminun Submerged 50.00 Ca3(PO4)2 NaAISi308 AIOOH Precipitate
5928-07-20225 Page 5 of 5 Contributions to Precipitates by Buffer 600.00 500.00 400.00 I 300.00 200.00 100.00 0.00 Ca3(PO4)2 NaAISi308 AIOOH Total Precipiates Type of Precipiete
- NaOHpH9.1 MTSPpH8.0