ML20217F185
| ML20217F185 | |
| Person / Time | |
|---|---|
| Site: | Hatch  |
| Issue date: | 03/27/1998 |
| From: | Olshan L NRC (Affiliation Not Assigned) |
| To: | Sumner H SOUTHERN NUCLEAR OPERATING CO. |
| References | |
| TAC-M99383, TAC-M99384, NUDOCS 9803310302 | |
| Download: ML20217F185 (8) | |
Text
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<f % rch 27,l1998, c
j Mr. H.' L - Sumrhr, Jr/
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Vice President -Nuclear..
Hatch Project.
e Southem Nuclear Operating
. Company, Inc.
. P. O. Box 1295 - _.
- Birmingham, Alabama 35201-1295
SUBJECT:
SECOND REQUEST FOR ADDITIONAL INFORMATION CONCERNING -
EXTENDED POWER UPRATE FOR EDWIN 1. HATCH NUCLEAR PLANT,.
UNITS 1 AND 2 (TAC NOS. M99383 AND M99384)
Dear Mr. Sumner:
By' l6 der dated February 10,1997, we sent you a request for additional information (RAI) concoming your August 8,1997, amendment request for extended power uprate. You responded by letter dated March 9,1998. Enclosed is another RAI that covers review areas not covered in our first RAl. Please advise us of your schedule for response.
Sincerely, Leonard N. Olshan, Senior Project Manager Project Directorate ll-2 Division of Reactor Projects - 1/II Office of Nuclear Reactor Regulation Docket Nos. 50-321 and 50-366
Enclosure:
As stated cc w/ encl: See next page Distnbution.
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WASHINGTON, D.C. 20066-0001 Yg*****p March 27,1998 Mr. H. L. Sumner, Jr.
Vice President -Nuclear Hatch Project Southersi Nuclear Operating Company, Inc.
P. O. Box 1295 Birmingham, Alabama 35201-1295
SUBJECT:
SECOND REQUEST FOR ADDITIONAL INFORMATION CONCERNING EXTENDED POWER UPRATE FOR EDWIN 1. HATCH NUCLEAR PLANT, UNITS 1 AND 2 (TAC NOS. M09383 AND M99384)
Dear Mr. Sumner:
By letter dated February 10,1997, we sent you a request for additional information (RAI) concerning your August 8,1997, amendment request for extended power uprate. You responded by letter dated March 9,1998. Enclosed is another RAI that covers review areas not covered in our first RAI. Please advise us of your schedule for response.
1 Sincerely, I
fL. h%
Leonard N. Olshan, Senior Project Manager Project Directorate ll-2 Division of Reactor Projects - 1/11 Office of Nuclear Reactor Regulation Docket Nos. 50-321 and 50-366
Enclosure:
As stated i
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cc w/ encl: See next page f
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L Edwin 1. Hatch Nuclear Plant cc:
Charles A. Patrizia, Esquire Mr. Emest L. Blake, Jr.
Paul, Hastings, Janofsky & Walker Shaw, Pittman, Potta 10th Floor and Trowbridge 129g Pennsylvania Avenue 2300 N Street, NW.
Washington, DC 20004-9500 Washington, DC 20037 Chairman Mr. D. M. Crowe Appling County Commissioners Manager, Licensing County Courthouse Southem Nuclear Operating Baxley, Georgia 31513 Company, Inc.-
P. O. Box 1295 Mr. J. D. Woodard
' Birmingham, Alabama 35201-1295 Executive Vice President Southem Nuclear Operating Resident inspector Company, Inc.
Plant Hatch P. O. Box 1295 11030 Hatch Parkway N.
Birmingham, Alabama 35201-1295 Baxley, Georgia 31531 Mr. P. W. Wells Regional Administrator, Region ll General Manager, Edwin 1. Hatch U.S. Nuclear Regulatory Commission
. Nuclear Plant Atlanta Federal Center Southem Nuclear Operating 1
61 Forsyth Street, SW, Suite 23T85 Company, Inc.
Atlanta, Georgia 30303 U.S. Highway 1 North P. O. Box 2010 Mr. Charles H. Badger Baxley, Georgia 31515 Office of Planning and Budget 1
- Room 610 Mr. R. D. Barker 270 Washington Street, SW.
Program Manager Atlanta, Georgia 30334 Fossil & Nuclear Operations Oglethorpe Power Corporation Harold Rehois, Director 2100 East Exchange Place Department of Natural Resources P. O. Box 1349 205 Butler Street, SE., Suite 1252 Tucker, Georgia 30085-1349 Atlanta, Georgia 30334 Steven M. Jackson Senior Engineer-Power Supply Municipal Electric Authority Lof Georgia
- 1470 Riveredge Parkway, NW Atlanta, Georgia 30328-4684 j
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REQUEST FOR ADDITIONAL INFORMATION EXTENDED POWER UPRATE HATCH NUCLEAR PLANT Containment Systgma and Severe Accidents
- 56. Enclosure 6 of NEDC-32749P, Section 4.1, did not include confirmMory calculations with '
the SHEX code and the HXSIZ code at the extended power level. Please prnv!de the comparative analysis results. Similar decay heat models should be used in SHEX code for both confirmatory and extended power level analyses for results to remain comparable.
57, Enclosure 6, Section 4.1.2.3, indicated that due to changes in operating conditions with extended power uprate, the actual asymmetrical loads will increase slightly but will remain within the design margins. Please quantify the results.
- 58. Enclosure 6, Section 4.5.2, indicated that the impact of an 8 percent increase in thermal power would cause the Unit 1 CAD System and Unit 2 recombiners to be initiated earlier.
Provide the time responses.
- 59.. For review of available containment pressure for the not positive suction head (NPSH),
please provide the key hasumptions used for the minimum containment pressure analyses.
Also provide the updated containment analyses pressure and temperature curves.
- 60. For review of used overpressure for Unit 1, please provide the NPSH calculations for residual heat removal and containment spray pumps. The results are tabulated on page E-5 of your 90-day response to Generic Letter 97-04, dated December 30,1997.
Probabilistic Safety Assessment
' 61. On page 10-7 (middle of the page), it is stated that "this analysis focused primarily on the evaluation of the considerations: initiating events, level 1 success criteria, and etc...." The GE's long term program cMes four types of probabilistic safety assessment (PSA) inputs and assumptions that may be affected by the uprate - which, in addition to the ones on the list, includes a consideration of component failure rates also. A discussion on how component failure rates may be changed by power uprate should be provided. If they are not expected to change, a basis should be provided.
- 62. On page 10-8, the top paragraph states that "it could be postulated that an increase in certain initiator event frequencies may occur over time due to the operation of the plant with decreased power margins as compared to those which existed at the initial licensed power level." Thus, rather than concluding, without further examination, that the extended power uprate would have no readily discemible adverse effect on initiator frequency, can it
- be shown through a sensitivity analysis that the impact of a presumed changed in the initiator event frequency may or may not result in a noticeable change in risk?.
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63 l On page 10-8, second to the last paragraph, the last sentence states that " success criteria
- were Judged to remain valid." Does this mean that there is no change in the success criteria, or that it may change, but still considered " valid?" If it is the latter, what is meant by
- valid?"
- 64. Please ident#y 50minant sequences and their contribution to the core damage frequency (CDF) increase - providing a discussion comparing the baseline and the new dominant
. sequences.
What percentage of the CDF increase (due to power uprate) is due to increase in operator error probabilities? Please provide a discussion on specific operator schons and their contributions to the increase in risk.'
- 65. On page 10-9, the first paragraph lists key operator actions. This list was formed from a review that was conducted to determine which accident scenarios involved changes in event timing that could significantly affect operator responses. What were the specific changes in the available response time for each of the operator actions on the list? And how were these changes in time reflected in the changed human error probabilities assumed for the operator actions on the list? Please list the newly assumed human error probabilities for each of these actions (list also the original base case probabilities). Along j
with a list of these human error probabilities, provide the bases for the newly assumed I
human error probabilities. Addition &lly, what were the bases for increasing the grid recovery probabilities by 0.02 and assuming a probability of 0.1032 for inadequate high pressure injection, which is twice the value employed in the original plant PSA?
- 66. On page 10-10, in the third paragraph, why was using the original PSA grid recovery probabilities considered more realistic when the list of significant operator actions (previous page) identified recovery of grid as an important operator action whose available response time may be shortened due to power uprate, thus resulting in a higher operator error probability? What is the basis for the change in the assumption?
- 67. On page 10-g, middle paragraph, the second sentence states that operator error probabilities were chosen to bound the impact of the 50 percent decrease in event times for a couple of the actions listed in the previous paragraph. On page 10-10, middle paragraph, the third sentence states "in light of small magnitude of the changes in the available time..." Does Hatch consider the 50 percent reduction in rssponse time availability small? If yes, what is the basis?
- 68. Given the results of Level 1 analysis (CDF increase was 6.6 percent for Unit 1 and 41 percent for Unit 2), what is the impact of these results on the containment? Please provide quantitative results for Level 2 analysis. As an example, increased operator error probability for vessel depressurization may affect mitigation of fire, resulting in an increased risk due to intomal fire.
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- 69. Please provide a discussion as to how uncertainty in human error probabilities as well as modeling uncertainty is addressed in the overall analysis - both qualitatively and 7
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3-Plant Systems
- 70. In Section 4.4, what effect does extended power uprate have on the total post-loss-of-coolant accident (LOCA) halogen loading and the total integrated dose calculated for the Standby Gas Treatment System?
- 71. Section 4.5.2 states that additional margin has been provided by designing the post-LOCA Combustible Gas Control System to control oxygen within'4 percent volume. Does the '
I margin encompass the increase in oxygen due to the extended power uprate?
- 72. Section 4.5.3 states that the increase in the radioactivity levels caused by operating at the higher power level would recult in an increase in the control room operator dose under post-LOCA conditions. Explain how much the dose would increase, and how the increase -
corresponds to the existing allowable dose to the control room operators.
- 73. In Table 6-2 on fuel pool cooling, explain what is meant by, " normal condition" for each area in the table. Why do the normal condition temperatures specified under the bulk fuel pool temperature area, exceed the maximum (core offload) condition temperatures?
- 74. Section 6.3 states that the spent fuel pool (SFP) heat loads will slightly increase resulting from plant operations at the proposed power level. Provide the following information:
- a. Provide / compare the host loads and corresponding peak calculated SFP temperatures (for plant operations at the current power level and at the proposed extended power uprate lew.y during planned refueling and unplanned full core offload. Single failure of
- the SFP cooling system does not need to be assumed for the unplanned full core
- offload,
- b. Is full core offload the general practice for planned refuelings?
- c. How many SFP cooling system trains will be available/ operable prior to a planned refueling outage or an unplanned full core offload?
- 75. In Section 6.3, what is the maximum temperature that the fuel racks are designed for, and what temperature would the racks actually experience with the extended power uprate?
- 76. In the unlikely event that there is a complete loss of SFR cooling capability, the SFP water
' temperature will rise and eventually will reach boiling temperature.~ Provide the time to boil (from the pool high temperature alarm caused by loss of-pool cooling) and the boil <,ff rate
- (based on the heat load for the unplanned full core offload scenario), Also, discuss sources and capacity of makeup water and the methods / systems (indicating system
. seismic design Category) used to provide the maksup water, u
- 77. In Section 6.4. what effect does extended power uprate have on the reactor building chilled
- water system and the service water that supplies the emergency diesel generators?
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. 78. In Section 7.1, explain how the main generator auxiliaries are capable of producing a higher electrical output while still meeting their design requirements (include the effect of the increased generator loads on the turbine building closed cooling water system).
- 79. Section 7.1 states that the planned modifications to the high pressure turt>ine and moisture separator reheaters should allow Unit 1 to operate at or near the new licensed power level with adequate turbine pressure control. Explain what is meant by should" for both Units 1 and 2.
- 80. Section 7.4 states that the feedwater regulating valves were originally designed for greater than rated flow conditions, have been evaluated for extended power uprate conditions, and -
are considered adequate. What are the original design flows of the feedwater regulating valves, and how do they compare with the flow conditions that result from extended power uprate?
- 81. Section 7.4 states that recent transient analyses have indicated that the system need only have the capacity to provide at least 105 percent of the extended power uprate feedwater J
flow to assure that the plant remains available during water level transients, avoids scrams, and minimizes challenges a plant safety systems. Explain what transient analysis is being referred to in this statement.
- 82. In Section 7.4, explain the impact of extended power uprate on the feedwater heater drains as a result of the higher flow rates.
- 83. In Section 10.1, how do the changes in feedwater, condensate, and reactor water cleanup temperatures impact the mass and energy release rates following high energy line breaks (HELBs)? Explain how the HELB effects, for outside the primary containment, were evaluated for the impact of extended power uprate? What is the impact of a steam jet air ejector steam line break as a result of extended power uprate?
- 84. In Section 10.1.1, explain how the structural / equipment HELB analysis for the original 5 percent power uprate for all systems evaluated in the Final Safety Analysis Report remains bounding for extended power uprate.
- 85. In Section 10.2.2, for the slightly increased extended power uprate temperature and pressure conditions, do the nonmetallic parts of nonelectrical equipment / components (pumps, heat exchangers, etc.) continue to meet the following design and qualification requirements:
- a. Components shall be designed to be compatible with the postulated environmental conditions, including those associated with LOCAs.
- b. Measures shall be established for the selection and review for suitability of application of materials, parts, and equipment that are essential to safety-related functions.
- c. Design control measures shall be established for verifying the adequacy of design.
- d. Equipment qualification records shall be maintained and shall include the results of tests and material analyses.
- 86. In Section 10.4, what testing will be performed on the feedwater and condensate systems
. prior to the implementation of extended power uprate?
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