ML20236F769
| ML20236F769 | |
| Person / Time | |
|---|---|
| Site: | River Bend  |
| Issue date: | 06/30/1998 |
| From: | Wigginton D NRC (Affiliation Not Assigned) |
| To: | Mcgaha J ENTERGY OPERATIONS, INC. |
| References | |
| GL-96-06, GL-96-6, TAC-M96858, NUDOCS 9807020324 | |
| Download: ML20236F769 (5) | |
Text
- _ _ _ - - _
n,
[
' Mr. John R. McGaha, Jr.
June 30, 1998 L
Vice President - Operations L
Entergy Operations, Inc.
l l'.
. River Bend Station -
t
' P. O. Scx 220 -
l L
. St. Francisville, LA 70775 l:
SUBJECT:
RIVER BEND STATION, UNIT 1 - REQUEST FOR ADDITIONAL INFORMATION REl.ATED TO GENERIC LETTER 96-06 (TAC NO. M96858)
Dear Mr. McGaha:
L l
Generic Letter (GL) 96-06, " Assurance of Equipment Operability and Containment Integrity l
During Design-Basis Accident Conditions," dated September 30,1996, included a request for '
- licensees to evaluate cooling water systems that serve containment air coolers to assure that '
c they are not vulnerable to waterhammer and two-phase low conditions. Entergy Operations, Inc.
j
~ provided its assessment of the waterhammer and two-phase flow issues for River Bend Station in letters dated January 28 and June 17,1997. In order to complete our review of the Entergy -
resolution of these issues, we will require additional information as discussed in the enclosure.
L
- In preparing your responses, you may wish to take advantage of the discussions we have had
- with the Nuclear Energy Institute (NEI) and resolutions that may be available from those l
discussions.
In' order for us to complete our review and to support our review schedule for GL 96-06, it is requested that you respond by August 30,1998. If you have any questions on this matter, please i
contact me at (301)-415-1301.
Sincerely,
- ORIGINAL SIGNED BY:
David L. Wigginton, Senior Project Manager g
l Project Directorate IV-1 Division of Reactor Projects lil/lV Office of Nuclear Reactor Regulation Docket No. 50-458 Enclosurei Request For Additionalinformation cc w/ encl: See next page
~ DISTR BUTION:
M WT PUBLIC PD4-1 r/f JHannon i
CHawes -
DWigginton TGwynn, RIV ACRS
.OGC (15B18)
EAdensam (EGA1)
Document Name: RBM96858.RAI -
Phlh1 LA/PD4-1'-
PD/FdlV OFC kNton/vw-Chaw [.JHarfnon NAME L
[ d0 - /98
. h/
(98-DATE
[/$0/98 COPY M NO:
YESlNOI NhO OFFIC.lAL ECORD COPY L/
t
- ua l
p' w a g a-armimagg s
p a rtz g
i UNITED STATES 4
j NUCLEAR REGULATORY COMMISSION 2
WASHINGTON, D.C. 20066 4001 l
\\*****/
June 30, 1998 i
i l
Mr. John R. McGaha, Jr.
Vice President-Operations Entergy Operations, Inc.
River Bend Station P. O. Box 220 St. Francisville, LA 70775
SUBJECT:
RIVER BEND STATION, UNIT 1 - REQUEST FOR ADDITIONAL INFORMATION RELATED TO GENERIC LETTER 96-06 (TAC NO. M96858)
Dear Mr. McGaha:
Generic Letter (GL) 96-06, " Assurance of Equipment Operability and Containment !ntegrity During Design-Basis Accident Conditions," dated September 30,1996, included a request for licensees to evaluate cooling water systems that serve containment air coolers to assure that they are not vulnerable to waterhammer and two-phase low conditions. Entergy Operations, Inc.
provided its assessment of the waterhammer and two-phase flow issues for River Bend Station in letters datec: January 28 and June 17,1997. In order to complete our review of the Entergy
' resolution of these issues, we will require additional information as discussed in the enclosure, in preparing your recponses, you may wish to take advantage of the discussions we have had I
with the Nuclear Energy Institute (NEI) and resolutions that may be available from those i
discussions.
in order for us to complete our review and to support our review schedule for GL 96-06, it is requestad that you respond by August 30,1998, if you have any questions on this matter, please contact me at (301)-415-1301.
Sincerely, O
4 David L.
g ton, Senior Project Manager Project Directorate IV-1 Division of Reactor Projects lil/IV Office of Nuclear Reactor Regulation Docket No. 50-458
Enclosure:
Request For AdditionalInformation cc w/ encl: See next page 4
l
't,
' Mr. John R. McGaha L Entergy Operations, Inc.
River Bend Station cc:
Winston & Strawn Executive Vice President and 1400 L Street, N.W.
Chief Operating Officer Washington, DC 20005-3502 Entergy Operations, Inc.
P. O. Box 31995 Manager-Licensing Jackson, MS 39286 Entergy Operations, Inc.
River Bend Station General Manager-Plant Operations P. O. Box 220 Entergy Operations, Inc.
St. Francisville, LA 70775 River Bend Station -
P. O. Box 220 Senior Resident inspector St. Francisville, LA 70775
- P. O. Box 1050 St. Francisville, LA 70775 Director-Nuclear Safety Entergy Operations, Inc.
4 President of West Feliciana River Bend Station i
Police Jury P. O. Box 220 P. O. Box 1921 St. Francisville, LA 70775 St. Francisville, LA 70775 Vice President - Operations Support Regional Administrator, Region IV Entergy Operations, Inc.
U.S. Nuclear Regulatory Commission P. O. Box 31995 -
611 Ryan Plaza Drive, Suite 1000 Jackson, MS 39286 1995' Arlington,TX 76011 Attomey General Ms. H. Anne Plettinger State of Louisiana 1
3456 Villa Rose Drive P. O. Box 94095 Baton Rouge, LA 70806 Baton Rouge, LA 70804-9095 l
Administrator.
Wise, Carter, Child & Caraway Louisiana Radiation Protection Division P. O. Box 651 -
P. O. Box 82135 Jackson, MS 39205 Baton Rouge, LA 70884-2135
=---.mm=-
REQUEST FM ADDITIONAL INFORMATION FOR RESOLUTION OF GL 96-06 ISSUES AT RIVER BEND (TAC NO. M96858)
Generic Letter (GL) 96-06, " Assurance of Equipment Operability and Containment Integrity During Design-Basis Accident Conditions," dated September 30,1996, included a request.
for licensees to evaluate cooling water systems that serve containment air coolers to assure that they are not vulnerable to waterhammer and twc-phase flow conditions. Entergy Operations, Inc.,(the licensee) provided its assessment of the waterhammer and two-phase flow issues for River Bend Station in letters dated January 28, and June 17,1997. The licensee indicated that waterhammer and two-phase flow vulnerabilities associated with the standby service water (SSW) system at River Bend were analyzed during the original design of the SSW system, and desigr: features were included to minimize and mitigate waterhammer occurrences. However, it is not clear that the concems expressed in GL 96-06 are encompassed by the previous analyses that have been completed. Therefore, the following additional information is requested:
- 1. Describe design features that exist and measures that have been taken to minimize and mitigate the effects of waterhammer and two-phase flow conditions in each of the cooling water systems that may be affected (e.g., ventilation chilled water system, normal service water system, SSW system). Describe in detail the specific waterhammer and two-phase flow scenarios that these design features and measures were intended to address.
- 2. Installing design features and implementing measures to minimize and mitigate the effects of waterhammer and two-phase flow conditions is an acceptable approach for addressing the waterhammer and two-phase flow concems. However, all scenarios must be considered to assure that the vulnerability to waterhammer and two-phase flow has been adequately addressed. Provide a detailed description of the " worst case" scenarios for waterhammer and two-phase flow for each of the cooling water systems that may be affected (e.g., ventilation chilled water system, normal service water system SSW system),
taking into consideration the complete range of event possibilities, system configurations, and parameters. For example, all waterhammer types and water slug scenarios should be considered, as well as temperatures, pressures, flow rates, load combinations, and potential component failures. Additional considerations applicable to two-phase flow conditions include:
the effects of vold fraction on flow balance and heat transfer; the consequences of steam formation, transport, and accumulation; cavitation, resonance, and fatigue offects; and erosion considerations.
Licensees may find NUREG/CR-6031, " Cavitation Guide for Control Valves," helpful in addressing some aspects of the two-phase flow analyses. (Note: it is important for licensees to realize that in addition to heat transfer considerations, two-phase flow also involves structural and system integrity concems that must be addressed). Confirm that all scenarios have been considered, including those where the affected containment penetrations are not isolated (if this is a possibility), such that the design features and measures that have been established are adequate for mitigating the effects of ENCLOSURE
ss 2
waterhammer and two-phase flow conditions for all postulated accident scenarios.
- 3. _ If a methodology other than that discussed in NUREG/CR-5220. " Diagnosis of l
Condensation-induced Waterhammer," was used in evaluating the effects of waterhammer, i
describe this altemate methodology ir. detail. Also, explain why this methodology is applicable and gives conservative results (typically accomplished through rigorous plant-specific modeling, testing, and analysis).
I
- 4. For both the waterhammer and two-phase flow analyses, provide the following information:
' a. Identify any computer codes that were used it the waterhammer and two-phase flow analyses and describe the methods used to bench mark the codes for the specific loading conditions involved (see Standard Review Plan Section 3.9.1).
- b. Describe and justify all assumptions and input parameters (including those used in any computer codes) such as amplifications due to fluid structure interaction, cushioning, I
speed of sound, force reductions, and mesh sizes, and explain why the values selected give conservative results. Also, provide justification for omitting any effects that may be relevant to the analysis (e.g., fluid structure interaction, flow induced vibration, erosion).
- c. Ccnfirm that the analyses included a complete failure modes and effects analysis (FMEA) for all components (including electrical and pneumatic failures) that could impact performance of the cooling water system and confirm that the FMEA is documented and available for review, or explain why a complete and fully documented FMEA was not performed.
- d. Determine the uncertainty in the waterhammer and two-phase flow analyses, explain how the uncertainty was determined, and how it was accounted for in the analyses to assure conservative results.
- e. Explain and justify all uses of " engineering judgement."
- 5. Confirm that the waterhammer and two-phase flow loading conditions do not exceed any design specifications or recommended service conditions for the piping system and components, including those stated by equipment vendors; and confirm that the system will i
continue to perform its design-basis functions as assumed in the safety analysis report for j
the facility and that the containment isolation valves will remain operable.
- 6. Discuss specific system operating parameters and other operating restrictions that must be maintained to assure that the waterhammer and two-phase flow analyses remain valid (e.g.,
head tank level, pressures, temperatures), and explain why it would not be appropriate to establish Technical Specification requirements to acknowledge the importance of these parameters and operating restrictions. Also, describe and justify reliance on any non-safety related instrumentation and controls in this regard.
- 7. Provide a simplified diagram of the affected systems, showing major components, active components, relative elevations, lengths of piping runs, and the location of any orifices and flow restrictions.
- 8. Describe in detail any plant modifications or procedure changes that have been made or are plenned to be made to resolve the waterhammer and two-phase flow issues, including completion schedules.
- _ - _ _ _ _ _ _ _ _ _ _ _ _ - _