ML071280517
| ML071280517 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 04/27/2007 |
| From: | Nietmann K Constellation Energy Group |
| To: | Document Control Desk, NRC/NRR/ADRO |
| References | |
| TAC MD4031 | |
| Download: ML071280517 (13) | |
Text
Kevin J. Nietmann 0Constellation Energy Nine Mile Point Nuclear Station P.O. Box 63 Lycoming, New York 13093 315.349.5200 315.349.1321 Fax April 27, 2007 U. S. Nuclear Regulatory Commission Washington, DC 20555-0001 ATTENTION:
SUBJECT:
Document Control Desk Nine Mile Point Nuclear Station Unit No. 2; Docket No. 50-4 10 License Amendment Request Pursuant to 10 CFR 50.90: Revision of Service Water and Ultimate Heat Sink Temperature Requirements - Technical Specification 3.7.1 -
Response to NRC Request for Additional Information (TAC No. MD403 1)
(a) Letter from T. J. O'Connor (NMPNS) to Document Control Desk (NRC), dated January 4, 2007, License Amendment Request Pursuant to 10 CFR 50.90:
Revision of Service Water and Ultimate Heat Sink Temperature Requirements -
Technical Specification 3.
7.1 REFERENCES
(b) Letter from D. V. Pickett (NRC) to T. J. O'Connor (NMPNS), dated March 29, 2007, Request for Additional Information Regarding Nine Mile Point Nuclear Station, Unit No. 2, Revision to Service Water System and Ultimate Heat Sink Temperature Requirements (TAC No. MD403 1)
Nine Mile Point Nuclear Station, LLC (NMPNS) hereby transmits supplemental information requested by the NRC in support of a previously submitted application for amendment to Nine Mile Point Unit 2 (NMP2) Renewed Operating License NPF-69. The initial application, dated January 4, 2007 (Reference a) proposed to revise NMP2 Technical Specification 3.7.1, "Service Water (SW) System and Ultimate Heat Sink (UHS)." The supplemental information, provided in Attachment (1) to this letter, responds to the request for additional information documented in the NRC's letter dated March 29, 2007 (Reference b). This supplemental information does not affect the No Significant Hazards Determination analysis provided by NMPNS in Reference (a).
Pursuant to 10 CFR 50.91(b)(1), NMPNS has provided a copy of this supplemental information to the appropriate state representative. This letter contains no new regulatory commitments.
A Co)I
Document Control Desk April 27, 2007 Page 2 Should you have any questions regarding the information in this submittal, please contact M. H. Miller, Licensing Director, at (315) 349-5219.
Very truly yours, K Fin J. Nietmann Acting Vice President Nine Mile Point STATE OF NEW YORK TO WIT:
COUNTY OF OSWEGO I, Kevin J. Nietmann, being duly sworn, state that I am Acting Vice President Nine Mile Point, and that I am duly authorized to execute and file this supplemental information on behalf of Nine Mile Point Nuclear Station, LLC.
To the best of my knowledge and belief, the statements contained in this document are true and correct.
To the extent that these statements are not based on my personal knowledge, they are based upon information provided by other Nine Mile Point employees and/or consultants. Such information has been reviewed in accordance with company practice and I believe it to be reliable.
Subscribed and sworn before me, a Notary Public in and for the State of New York and County of Oswego, this al*-?
day of 2007.
WITNESS my Hand and Notarial Seal:
Notary Public Date My Commission Expires:
SANDRA A. OSWALD Notary Public, State of New York No. 01OS6032276 Qualified in Oswego Count Commission Expires If-,
KJN/DEV
Document Control Desk April 27, 2007 Page 3 Attachments:
(1) Nine Mile Point Unit 2 - Response to NRC Request for Additional Information Regarding Proposed Revision to Technical Specification 3.7.1 cc:
S. J. Collins, NRC M. J. David, NRC Resident Inspector, NRC J. P. Spath, NYSERDA
ATTACHMENT (1)
NINE MILE POINT UNIT 2 RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION REGARDING PROPOSED REVISION TO TECHNICAL SPECIFICATION 3.7.1 Nine Mile Point Nuclear Station, LLC April 27, 2007
ATTACHMENT (1)
NINE MILE POINT UNIT 2 RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION REGARDING PROPOSED REVISION TO TECHNICAL SPECIFICATION 3.7.1 By letter dated January 4, 2007, Nine Mile Point Nuclear Station, LLC (NMPNS) submitted a license amendment request to revise Nine Mile Point Unit 2 (NMP2) Technical Specification (TS) 3.7. 1, "Service Water (SW) System and Ultimate Heat Sink (UHS)." This attachment provides supplemental information in response to the request for additional information documented in the NRC's letter dated March 29, 2007. Each individual NRC request is repeated (in italics), followed by the NMPNS response.
RAINo. 1 In Section 4.2.1.3 of the request, it states, "The long-term post-LOCA [loss-of-coolant-accident] drywell temperature profile would be several degrees higher because of the impact of the higher UHS temperature on RHR [residual heat removal] heat exchanger heat removal capacity."
Provide information on the post-LOCA temperature profile and equipment qualification profile and safety margin between the two temperature profiles. Explain what actions are to be taken to maintain drywell temperature within a limit that can ensure the validity of the equipment qualification temperatures previously approved.
Response
The composite environmental qualification (EQ) temperature profile that is used to establish environmental qualification of electrical equipment important to safety for equipment in the drywell is plotted on Figure 1 for the first 30 days post-accident. Also plotted on Figure 1 are the calculated long-term post-LOCA containment temperature responses assuming UHS (SW) temperatures of 82TF and 84TF. Beyond 30 days, the EQ profile remains constant at 150TF, whereas the calculated post-LOCA temperature continues to decrease with ongoing containment heat removal via the RHR heat exchangers.
Since the composite EQ drywell temperature profile remains bounding for the 2TF increase in UHS (SW) temperature (to 84TF), the margin between the composite EQ drywell temperature profile and the qualification test profiles for the equipment remains unchanged. Thus, no actions are required to ensure the validity of the EQ temperatures previously approved.
The calculated long-term post-LOCA containment temperatures plotted on Figure 1 were based on the following RHR heat exchanger performance assumptions:
For the 82TF SW case: K = 239 Btu/sec- °F (Original analysis, based on 5% tube plugging and design fouling.)
For the 84TF SW case: K = 244.3 Btu/sec- °F (Consistent with the NMP2 power uprate analysis, based on 3% tube plugging and design fouling. See the response to RAI No. 2 below for further discussion.)
RAINo. 2 There is no information in the request regarding which computer code was used to analyze the thermal and hydraulic performance of the RHR heat exchangers or whether it was updated Provide information on the computer code used for the analysis and accuracy of the analysis compared with other recognized calculation methods.
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ATTACHMENT (1)
NINE MILE POINT UNIT 2 RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION REGARDING PROPOSED REVISION TO TECHNICAL SPECIFICATION 3.7.1
Response
A computer code was not used to analyze the thermal and hydraulic performance of the RHR heat exchangers for the proposed 2°F increase in UHS (SW) temperature to 84°F. Hydraulic performance is not impacted, since the heat exchanger flow rates have not changed from the existing analysis. The heat exchanger thermal performance is calculated using the effectiveness (NTU) method (i.e., Q = Kx (Thot-inlet Tcold-inlet), which requires heat exchanger data including the overall heat transfer coefficient, design basis fouling, and flow rates. For the current design basis containment analysis, General Electric (GE) supplied the following RHR heat exchanger performance characteristics for a UHS (SW) temperature of 82°F and 5% tube plugging:
U = 271 Btu/hr-ft2-OF K = 240.2 Btu/sec-°F A = 4240 ft2 (5% tube plugging)
The K value is adjusted (using the NTU method) to account for the increased effective area (A) due to reducing the RHR heat exchanger tube plugging limit from 5% to 3%, resulting in the following revised parameters:
U = 271 Btu/hr-ft2-OF K = 244.3 Btu/sec-OF A = 4339 ft2 (3% tube plugging)
With the increase in UHS temperature to 84°F and the revised K value of 244.3 Btu/sec- °F (for 3% tube plugging), the RHR heat exchanger heat removal from the suppression pool from 201'F to 21 1F is approximately the same as with a UHS temperature of 82°F with 5% tubes plugged. This is illustrated in Figure 2 and in Table 1 below.
Table 1 RHiR Heat Exchanger Heat Removal Comparison UHS = 84°F UHS = 827F K=244.3 K=240.2 Temp 3% tubes plugged 5% tubes plugged Ratio, Q84 / Q82 (0F)
Btu/hr Btu/hr 211 111,693,960 111,548,880 100.13%
210 110,814,480 110,684,160 100.12%
208 109,055,520 108,954,720 100.09%
206 107,296,560 107,225,280 100.07%
204 105,537,600 105,495,840 100.04%
202 103,778,640 103,766,400 100.01%
201 102,899,160 102,901,680 100.00%
200 102,019,680 102,036,960 99.98%
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ATTACHMENT (1)
NINE MILE POINT UNIT 2 RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION REGARDING PROPOSED REVISION TO TECHNICAL SPECIFICATION 3.7.1 The K-factor method is conservative since "U" is maintained at a constant value. This U value takes into account the design fouling. This is demonstrated using the K-factor analysis with a constant U and comparing it to a heat exchanger analysis using the computer program PROTO-HX using design fouling only. The heat exchanger analysis calculates "U" based on the increased differential temperature; as such, a higher heat removal capacity is realized, as illustrated on Figure 2.
Testing of the RHR heat exchanger is performed consistent with the Heat Transfer Test Methods specified in EPRI TR-107397, "Service Water Heat Exchanger Testing Guidelines." Collected heat exchanger test data is extrapolated to design conditions using the PROTO-HX program, Shell and Tube Heat Exchangers Module (Version 4.00). The uncertainties in the program's empirical correlations produce model analytical uncertainties of approximately +/- 10% of the U value.
The heat exchanger testing performed in 2004 for the "B" RHR heat exchanger determined that the projected heat duty when extrapolated to design conditions, and considering test uncertainties, was 44.68 MBtu/hr. Likewise, testing of the "A" RHR heat exchanger in 2007 yielded a projected heat duty of 45.7 MBtu/hr. The required heat removal capacity at design conditions is 33.08 MBtu/hr. The substantial margin in the test results are related to the RHR heat exchanger fouling assumptions. The 2004 performance testing of the "B" heat exchanger indicated an "as tested" overall fouling of 0.000189, and the 2007 testing of the "A" heat exchanger indicated an "as tested" overall fouling of 0,000099. The overall fouling factor assumed in the plant safety analyses is 0.001649 (0.001 for the tube side and 0.0005 for the shell side). Thus, the as-tested RHR heat exchanger performance is significantly better than the design performance assumed in the plant safety analyses.
RAI No. 3 In Section 4.2.1.4 of the request, it states, "Post-LOCA suppression pool cooling is provided by the RHR system, which is cooled by the SW system. The calculated peak post-LOCA suppression pool water temperature for power uprate conditions (rated thermal power of 3,467 MWt) is approximately 4YF below the 212'F design limit. This analysis was based on a UHS temperature of 82YF and also assumed that 5 percent of the RHR heat exchanger tubes are plugged " Justify that the peak suppression pool temperature design limit would not be exceeded for a LOCA with the UHS temperature continuously at 84YF. Please validate it with a computer analysis.
Response
As noted in Section 4.2.1.4 of Attachment (1) to the initial NMPNS license amendment request submittal dated January 4, 2007, the present RHR heat exchanger tube plugging limit is 3%. The 3% limit was established in conjunction with evaluations performed by NMPNS in support of License Amendment No.
113, which was issued by NRC letter dated May 7, 2004 (TAC No. MC0594). As demonstrated in the response to RAI No. 2 above, the RHR heat exchanger heat removal capability with 3% tube plugging and 84°F SW inlet temperature is essentially the same as the heat removal capability with 5% tube plugging and 82TF SW inlet temperature. Thus, the 40F margin between the peak calculated post-LOCA suppression pool temperature and the 212'F design limit, together with limiting the allowable RHR heat exchanger tube plugging to 3%, is adequate to accommodate the proposed 2'F increase in UHS temperature to 84'F.
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ATTACHMENT (1)
NINE MILE POINT UNIT 2 RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION REGARDING PROPOSED REVISION TO TECHNICAL SPECIFICATION 3.7.1 RAI No. 4 In Section 4.1.2.2 of the request, it states, "The three RBCLC [reactor building closed loop cooling]
system heat exchangers are cooled by the SW system." Provide information on the impact of increased SW temperature on the RBCLC system inside the drywell. Explain whether the cooling water system that is cooled by degraded UHS conditions can maintain equipment operability inside the drywell.
Response
As discussed in Updated Safety Analysis Report (USAR) Section 9.2.2, RBCLC system temperature is controlled by bypassing part of the component cooling water flow around the RBCLC heat exchangers. A temperature control valve is provided to regulate flow through the heat exchangers to maintain the desired temperature. In accordance with the system operating procedure, a normal RBCLC supply temperature of 86°F is maintained, which is 9°F below the design supply temperature of 95°F. Normally, two of the three RBCLC heat exchangers are in service. The standby (third) RBCLC heat exchanger is placed in service when the UHS (SW) temperature is greater than 72TF. In the event of increasing RBCLC supply temperature, heat loads on the RBCLC system would be reduced in accordance with operating procedure instructions. For example, the spent fuel pool cooling heat exchangers could be cooled directly by the SW system instead of the RBCLC system (a heat load of approximately 16 million Btu/hr). With three RBCLC heat exchangers in service and the system heat loads managed in accordance with operating procedures, the RBCLC supply temperature can be maintained less than its design limit of 95°F when the UHS (SW) temperature is 84TF.
Since the RBCLC supply water temperature can be maintained at or below its design value of 95TF for all anticipated conditions, there will be no impact on the performance capabilities of the equipment serviced by the RBCLC system, including equipment inside the drywell.
RAINo. 5 The reactor building closed loop cooling system is used post-LOCA to provide longer term cooling water for the control room chillers, spent fuel pool system, and instrument air compressors. Provide information on how these systems and components are to be affected by the degraded ultimate heat sinks.
Response
The control room chillers are cooled by the service water (SW) system and not by RBCLC system. The impact of operation with 84TF SW on the control room chillers is discussed in Section 4.1.1.3 of Attachment (1) to the initial NMPNS license amendment request submittal dated January 4, 2007. As concluded therein, control building design basis temperatures can be met for all operating and postulated accident conditions at a UHS (SW) temperature of 84TF.
The spent fuel pool cooling heat exchangers are normally cooled by the RBCLC system, and may alternatively be cooled directly by the SW system. As discussed in the response to RAI No. 4 above, since the RBCLC supply water temperature can be maintained at or below its design value of 95TF for all anticipated conditions, the spent fuel pool cooling system will be capable of maintaining the spent fuel pool water temperature within design limits when the UHS (SW) temperature is 84TF. As noted in the 4 of 9
ATTACHMENT (1)
NINE MILE POINT UNIT 2 RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION REGARDING PROPOSED REVISION TO TECHNICAL SPECIFICATION 3.7.1 discussion provided in Section 4.1.1.11 of Attachment (1) to the initial NMPNS license amendment request submittal dated January 4, 2007, there is ample margin between the calculated peak spent fuel pool temperatures and the fuel pool temperature design limits.
The three instrument air compressors (all non-safety related) are cooled by the RBCLC system. Normally only one compressor is running to support plant operation, a second compressor serves as a lag unit, and the third compressor is a backup. The RBCLC system can support operation of all three air compressors with the RBCLC supply temperature being no higher than its design temperature of 95TF. As discussed in the response to RAI No. 4 above, since the RBCLC supply water temperature can be maintained at or below its design value of 95TF for all anticipated conditions, there will be no impact on the performance capabilities of the air compressors when the UHS (SW) temperature is 84°F.
RAINo. 6 In Section 4.2.1.1 of the request, it states, "The differential temperature between the 84YF SW and the TS-required pool temperature limit is adequate to ensure that the suppression pool can be maintained within the TS-required temperature limits; therefore, the accident analysis initial condition is not affected."
Per TS 3.6.2.1, "Suppression Pool average Temperature," Limiting Condition for Operation (LCO) 3.6.2.1.a., which is applicable to reactor operating modes 1, 2, and 3, suppression pool average temperature shall be < 90Y1 with THERMAL POWER > 1% RTP [Rated Thermal Power] and no testing that adds heat to the suppression pool is being performed;"
If the average temperature of the suppression pool is > 90YF and <llO°F, the required action for this LCO is that the pool average temperature should be restored to < 900Y within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, otherwise the reactor thermal power should be reduced to < 1% RTP within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. Please confirm that analysis was performed to verify that with a SW temperature of 84YF, the RHR system heat exchanger can bring the suppression pool temperature at or below its TS limit of 90°F from 110F within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. Please provide the time duration for which the one RHR heat exchanger has to operate to bring the suppression pool temperature to 90YF using 84YF SW temperature and 82YF SW temperature, starting from the same initial suppression pool temperature of 110 YF, and with the design basis heat exchanger tube plugging and fouling factor.
Response
Suppression pool cooldown time from 1 10TF to 90TF is shown in Figure 3. Cases were run for both 82TF and 84TF SW temperature and are base on operation of one RHR heat exchanger. The RHR heat exchanger K values used were as discussed in the response to RAI No. 2; i.e.:
For the 82TF SW case: K = 240.2 Btu/sec- °F (based on 5% tube plugging and design fouling)
For the 84TF SW case: K = 244.3 Btu/sec- °F (based on 3 % tube plugging and design fouling)
As shown in Figure 3, the cooldown time is less than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> for both cases.
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ATTACHMENT (1)
NINE MILE POINT UNIT 2 RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION REGARDING PROPOSED REVISION TO TECHNICAL SPECIFICATION 3.7.1 RAINo. 7 NMP2 Updated Safety Analysis Report Table 6.2-9 specifies an initial drywell temperature of 135YF used for LOCA containment response analysis. Please confirm that analysis was done to verify that with the SW temperature of 84YF, assuming design basis tube plugging and fouling factors for the RBCLC water heat exchangers and drywell coolers, the drywell can be maintained at or below 135YF during normal plant operation. If the analysis shows that the drywell temperature exceeds 135YF, what is the impact on LOCA maximum drywell pressure and steam line break maximum drywell temperature?
Response
As discussed in the response to RAI No. 4 above, since the RBCLC supply water temperature can be maintained at or below its design value of 95TF for all anticipated conditions, there will be no impact on the performance capabilities of the drywell coolers and they will be capable of maintaining the drywell temperature less than 135TF when the UHS (SW) temperature is 84TF. With the initial condition of the safety analyses maintained, the safety analysis results will be unaffected.
The average drywell temperature is normally between 110°F to 1 15TF with a RBCLC supply temperature of 86TF. Thus, there is a large margin to the containment analysis initial condition value of 135TF listed in USAR Table 6.2-9.
RAI No. 8 Section 4.3.1 of the request, the third sentence states, "The peak suppression pool temperature corresponding to an 84YF UHS temperature has been evaluated and found to be within the ATWS
[anticipated transient without scram] pool temperature limit of 1907F." What was the peak suppression pool temperature calculated in the evaluation and how was it calculated?
Response
Subsequent to the January 4, 2007, NMPNS license amendment request submittal, the anticipated transients without scram (ATWS) analysis was re-performed for the NMP2 ARTS/MELLLA project. The NMP2 ARTS/MELLLA license amendment request was submitted by NMPNS letter dated March 30, 2007. The ATWS suppression pool temperature transient analysis was performed by General Electric utilizing the computer model ODYNVO9 for the reactor transient analysis and the computer model STEMP04 for the suppression pool heatup analysis. This analysis was performed with an assumed service water (UHS) temperature of 840F. The highest calculated peak suppression pool temperature was 155TF, which is well below the ATWS limit of 190TF.
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ATTACHMENT (1)
NINE MILE POINT UNIT 2 RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION REGARDING PROPOSED REVISION TO TECHNICAL SPECIFICATION 3.7.1 Figure I EQ Enveloped Containment Temperature (30 days)
(UHS Temperature 82°F vs 84°F) 220 210 200 190 180 E
I 170 160 150 140 130 120 110 0
5 10 15 20 25 Time Post-LOCA (days) 30 170 82o N
84°F EQ Envelope I
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ATTACHMENT (1)
NINE MILE POINT UNIT 2 RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION REGARDING PROPOSED REVISION TO TECHNICAL SPECIFICATION 3.7.1 Figure 2 Comparison of Heat Removal Capacity (UHS Temperature 82°F vs 84°F) 1.3E+08
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140 160 180 200 Suppression Pool Temperature (F) 8 of 9
ATTACHMENT (1)
NINE MILE POINT UNIT 2 RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION REGARDING PROPOSED REVISION TO TECHNICAL SPECIFICATION 3.7.1 Figure 3 Suppression Pool Cooldown Time from 110°F to 90°F at Lake Water Temperature (820F vs 840F) 115 e
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10 12 14 16 18 20 22 24 Time (Hours) 9 of 9