LIC-13-0088, Response to Request for Additional Information Fort Calhoun Station License Amendment Request to Revise Technical Specification 2.16, River Level
| ML13183A390 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun  |
| Issue date: | 06/27/2013 |
| From: | Cortopassi L Omaha Public Power District |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| LIC-13-0088 | |
| Download: ML13183A390 (5) | |
Text
.ýýtLl Omaha Public Power9WDict 444 South 161h Street Mall Omaha, NE 68102-2247 LIC-13-0088 June 27, 2013 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001
References:
- 1. Docket No. 50-285
- 2. Letter from OPPD (D. J. Bannister) to NRC (Document Control Desk), License Amendment Request (LAR) 12-03, Proposed Change to Revise Operating Requirements for Technical Specification 2.16, River Level, and Establish Emergency Action Level Classification Criteria for External Flooding Events under the Radiological Emergency Response Plan for Fort Calhoun Station, dated April 27, 2012 (LIC 0056) (ML12121A565)
- 3. Email from NRC (L. E. Wilkins) to OPPD (B. R. Hansher), DRAFT: RAI for Fort Calhoun Station Re: River Level and Emergency Action Levels (ME8550), dated March 27, 2013 (NRC-13-0053)
SUBJECT:
Response to Request for Additional Information re: Fort Calhoun Station License Amendment Request to Revise Technical Specification 2.16, River Level The Omaha Public Power District (OPPD) provides the responses to the Nuclear Regulatory Commission's (NRC's) request for additional information (RAI) regarding the license amendment request (LAR) to revise Technical Specification (TS) 2.16 for the Fort Calhoun Station (FCS), Unit No. 1, in the enclosure to this letter.
In Reference 2, OPPD submitted an LAR to revise TS limiting condition for operation (LCO) 2.16, River Level, and TS surveillance requirement 3.2, Equipment and Sampling Tests, Table 3-5, Minimum Frequencies for Eqciipment Tests. In addition, the amendment would revise the FCS Radiological Emergency Response Plan declaration procedure as licensed in the safety evaluation report for conversion of the emergency action levels (EALs). The NRC staff has reviewed the Reference 2 submittal and has determined that additional information is needed for the staff to complete its evaluation.
Reference 3 provided the NRC's RAIs regarding the FCS LAR to revise TS 2.16.
There are no regulatory commitments in this letter. If you should have any questions, please contact Mr. Bill Hansher, Supervisor - Nuclear Licensing, at (402) 533-6894.
1declare u er penalt of perjury that the foregoing is true and correct. Executed on June 27, 2013.
ouis P. Cortopassi Site Vice President and CNO
Enclosure:
OPPD's Responses to Request for Additional Information re: River Level LAR c: A. T. Howell, NRC Regional Administrator, Region IV J. M. Sebrosky, NRC Senior Project Manager L. E. Wilkins, NRC Project Manager J. C. Kirkland, NRC Senior Resident Inspector AIo(
Employment with Equal Opportunity
LIC-13-0088 Enclosure Page 1 of 4 Omaha Public Power District Response to Request for Additional Information Fort Calhoun Station LAR to Revise TS 2.16, "River Level" By letter dated April 27, 2012 (Agencywide Documents Access and Management System Accession No. ML12121A565), Omaha Public Power District (OPPD, the licensee) submitted a license amendment request for Fort Calhoun Station, Unit 1 (FCS). The proposed amendment would revise Technical Specification (TS) LCO 2.16, River Level, and TS surveillance requirement 3.2, Equipment and Sampling Tests, Table 3-5, Minimum Frequencies for Equipment Tests. In addition, the amendment would revise the FCS Radiological Emergency Response Plan declaration procedure as licensed in the safety evaluation report for conversion of the emergency action levels.
The NRC staff has reviewed your submittal and has determined that additional information is needed for the staff to complete its evaluation.
Page 13 of the enclosure states:
At low river levels, debris and/or ice on the traveling screens and/or trash racks can cause significant head loss potentially reducing intake cell levels below the RW pump mean sea level of 976 feet 9 inches. As a precaution, the level of the river and the intake cells is continuously monitored when river level is below 980 feet.
The proposed TS Required Actions states:
(3) At Missouri River levels less than 980 feet or greater than 1002 feet mean sea level, a continuous watch will be maintained to monitor river levels to assure no sudden loss of water supply occurs on low river level and provide adequate response time for rising river levels.
1.) Please provide further justification for using river level as the monitored parameter for low river level TS requirements when phenomena such as screen loading, etc, can cause a difference between the observed river level and the intake cell level.
Technical Specifications (TS) limiting condition for operation (LCO) 2.16, River Level, is the current specification which specifies maximum and minimum Missouri River levels which must be present to assure safe reactor operation at Fort Calhoun Station (FOS). It is currently applicable to Missouri River level as measured at the intake structure at FCS. The proposed change does not revise that aspect of TS 2.16. The monitored parameter is river level at the intake structure because the purpose of the specification is to ensure that the river level is within the specified range (2: 976 feet 9 inches and < 1004 feet). To facilitate this, the actual river level must be monitored at levels within this range to ensure no sudden loss of water supply occurs as river levels decrease, hence the continuous watch being established at 980 feet, and to provide adequate response time for rising river levels, hence the continuous watch being established at 1004 feet.
The purpose of the TS 2.16 LCO for river level is not to establish the raw water (RW) pump minimum operability requirements but rather to establish actions for high river levels for flood protection, which model NUREG-0212, Revision 2. The TS LCO 2.4, Containment Cooling,
LIC-13-0088 Enclosure Page 2 of 4 applies to the operating status of the containment cooling systems to assure operability of equipment required to remove heat from the containment during normal operating and emergency situations, including the RW system pumps. TS LCO 2.4 currently addresses RW system operability when head losses are significant and may vary from cell to cell affecting one or more RW pumps and the proposed license amendment does not impact TS 2.4.
The Intake Structure consists of three cells separated by concrete walls perpendicular to the river.
Two cells (A & C) contain one RW pump each and one cell (B) contains two RW pumps. Flow through each cell is independent of the other two. The RW pumps can obtain suction from any circulating water (CW) pump cell via a pair of sluice gates; even if the CW pumps are shutdown.
The minimum river level of 976 feet 9 inches provides adequate suction to the RW pumps for cooling plant components. The minimum submergence level (MSL) of water required for operability of the RW pumps applies to the cell level at the pump suction, which can be lower than river level due to head losses across the trash racks and traveling screens that may result from ice or debris. The minimum river level of 976 feet 9 inches is the lower limit of operability for the RW pumps when head losses are negligible for all cells. The minimum elevation of the RW pump suction is 973 feet 9 inches. The RW pumps have a minimum submergence design value of three (3) feet which equates to the 976 feet 9 inches intake cell level. During low cell level conditions, there is margin in the RW pump MSL. Preliminary data received from Flowserve indicates that the RW pumps have significant available margin within this 3 feet minimum submergence that more than accounts for any head loss effects due to icing or debris on the screens which indicates that the RW pumps can operate below the minimum TS river level requirements. This supports the use of river level as the monitored parameter for TS 2.16.
In addition, the Updated Safety Analysis Report (USAR) Section 9.8 indicates that although intake cell levels are also adversely affected by the flows associated with the non-safety related CW pumps (since the large flow rates associated with the CW pumps create significant head losses even with relatively clean intake cell conditions), the CW pumps have a much higher MSL requirement (983 feet 0 inches) and would become unstable and trip or be manually shutdown well before intake cell levels decrease to the RW pump MSL of 976 feet 9 inches. The head loss associated with CW pump flow would then be recovered and intake cell levels would rise.
2.) The proposed TS may not meet the requirements of 10 CFR 50.36. The TS Basis mention the intake cells but TS Bases are technically not part of TS. Please explain why there is no mention of the intake cells in the proposed Required Action (3).
The reason this TS change is being proposed is to address a non-cited violation of 10 CFR 50.36(c)(2)(ii)(B) transmitted in the letter from the NRC (J. A. Clark) to OPPD dated July 26, 2010, (ML102080231) which identified that TS LCO 2.16 is inadequate should the Missouri River exceed 1009 feet mean sea level (msl). Specifically, the non-cited violation stated that the reactor cannot be placed in a cold shutdown condition using normal operating procedures when the river level exceeds 1009 feet msl, as described in Technical Specification 2.16, "River Level."
As a result, OPPD proposed to revise TS LCO 2.16 to address the high river level concerns and retain the existing low river level requirements in the current licensing basis. The verbiage provided in the proposed TS Required Action (3) is not a new TS required action; it is simply a renumbered and reworded version of the existing TS 2.16(2) for providing the continuous watch to monitor river levels to assure no sudden loss of water supply occurs at river levels less than 980 feet and to ensure that adequate steps are taken on rapid rise of river level.
LIC-13-0088 Enclosure Page 3 of 4 The intent of this required action is to continue the current practice of invoking the continuous watch of the river level in the event there is a "change" in river level(s). Therefore, there is no mention of the intake cells in the proposed Required Action (3), which models NUREG-0212, Revision 2, Standard Technical Specifications for Combustion Engineering Pressurized Water Reactors,Sections 3/4.7.6, Flood Protection.
The existing verbiage related to the cell level in the TS Basis Section for TS LCO 2.16 was added in accordance with TS 5.20d, Technical Specification Bases Control Program, in October 2007 via TSBC 07-002-0, which provided additional guidance in the TS Bases for TS 2.16 and TS 2.4.
Specifically, the TS Basis verbiage was added to provide additional insight and guidance on the effect of suction side head losses on RW pump operability and clarify that the TS 2.16 low river level of 976 feet 9 inches is the lower limit of operability for all four RW pumps when negligible head losses are present. Existing plant procedures direct Operations personnel to continuously monitor intake conditions for river levels less than 980 feet 0 inches which provide acceptable margin above the lower limit to ensure that operability is maintained or that appropriate actions are taken. Also, per the TS Basis for TS 2.16, when the continuous watch requirement is in effect, in addition to river level, the level of the intake cells is monitored.
As explained in the FCS Updated Safety Analysis Report (USAR) Section 9.8.6, the Corps of Engineers adjusts winter releases from Gavins Point as necessary to accommodate the needs of all Missouri River water users. Normally, the water level is maintained higher than 983.0 feet.
Although agreement between OPPD and the Corps of Engineers to maintain minimum river water levels has not been formalized, the Corps of Engineers does cooperate with OPPD in these matters and would provide additional flow from upstream dams if such conditions would be impending. The time required for severe ice blockage of the river to occur extends into many hours and the weather conditions which would cause blockage would be evident over a period of a few days. Even lower river water levels would not be detrimental to plant safety since the MSL on the RW pumps is 976 feet 9 inches or more than six feet below the controlled minimum river water level.
Based on the existing plant design, once the river level reaches 983 feet, the non-safety related CW pumps, which have a much higher MSL (983 feet 0 inches) would become unstable and trip or be manually shutdown well before intake cell levels decrease to the RW pump MSL. The head loss associated with CW pump flow would then be recovered and intake cell levels would rise. At low river levels, debris and/or ice on the traveling screens and/or trash racks can cause significant head loss potentially reducing intake cell levels below the RW pump MSL. As a precaution, in addition to the river level, the level of the intake cells is continuously monitored when river level is below 980 feet. In addition, due to the higher MSL of the CW pumps, the proposed required action TS 2.16(2) for placing the reactor in HOT SHUTDOWN within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> of reaching the 976 feet 9 inches will be met well before the 980-foot river level when the continuous watch is established. (Figure 1 depicts the river levels with respect to the RW and CW pumps suction.)
In conclusion, the purpose of the continuous watch is to monitor for the "rate of change" in river level to ensure sufficient time to take the additional required action. Likewise, above 1002 feet msl, the continuous watch monitors the "rate of change" to ensure sufficient time to take actions outside of the intake structure to protect the plant for rising river levels.
LIC-1 3-0088 Enclosure Page 4 of 4 Figure 1 1007'6 II--
[I-97'0 Elevations Approximate