ML20127J202
| ML20127J202 | |
| Person / Time | |
|---|---|
| Site: | Grand Gulf  |
| Issue date: | 01/12/1993 |
| From: | Cottle W ENTERGY OPERATIONS, INC. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| GNRO-93-00003, GNRO-93-3, NUDOCS 9301250063 | |
| Download: ML20127J202 (7) | |
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W. T. cottle Janu ry 12, 1993 i
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U.S. Nuclear Regulatory Commission Mail Station F1-137 Washington, D.C.
205S5 Attention:
Dccumenc Control Desk Subiect:
Grand Gu.f Nucicer Statior.
Unit 1 bocket No. 50-416 License No. NPF-29 Change of Commitments on Containment Isolation Valves During Station Blackout GNRO-93/00003 Gentlemen:
In response to the Station Blackout (S89) rule and based on NRC guidance of 2
the time, Grand Gulf Nuclear Station (GGNS) co.nmitted to manually close 28 containment isolation valves (CIVs) during SB0 conditions in the event core damage became imminent (see GNR0-91/00153).
During implementation of the commit nents the o,erations staff raised concerns over the appropriateness of the actions which cauld make some safety systems unavailable and cause conflict with some of the symptom based Emergency Procedures.
Additionally, manual closure of some of the CIVs would require unwctranted operator actions that could divert operator attention away from activities that are more appropriate.
The concerns prompted a review to determine if additional CIV exclusion criteria could reasonably be applied to GGNS.
Our review indicated that two new criteria were applicable in addition to those previously used for exclusion of CIVa. The new criteria identified were:
1.
Valves that are required by station procedures to be closed during normal operation at all times (except for brief intervals durir-testing) and aru expected to remain closed dating an SB0 (as lu g as position indication is available in the control room p;ior to the SBO).
ii. Valves in radioactive closed loops that are not expected to be breached during a station blackout provided these loops (a) connect directly to the suppression pool, (b) are provide with a single isolt. tion valve, (c) are always submerged thereby proventing the escape of containment atmosphere and (d) where t.he piping oucside i
containmcnt constitutes a closed system providing a second isolation barrier following a single active failure.
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j It should he noted that GGNS already considers the closed system outside centainment to be a redundant containment isolation provision as indicated j
in the GGNS Updated Final Safety Analysis Report (UFSAR) in Table 6.2-49 and is in compliance with 10CFR50, Appendix A GDC 54 and with U.S. NRC i
Standard Raview Plan 6.2.4, Containment Isolation Provisions.
Our review not only identified new exclusion criteria, but more importantly reopened the discussion of related safety issues.
It is essential that the actions taken by operators to mitigate the consequences of an event during an SB0 are directed towards activities that provide real safety benefits.
Since the SB0 scenario does not assume a single failure in addition to the j
failures resulting in an SBO, the additional exclusion criteria are consistent with the intent of the SB0 rule. Additionally, the closure of most of the valves identified in our review could be in conflict with the requirements of BWROG Emergency Procedura Guideline Rev. 4 Appendix B to l
which GGNS is committed.
Although valves E51-F063 and 64, E22-F004, and E12F027A and B do not strictly meet the two aforementioned criteria, safety
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raruifications necessitate their exclusion.
4 Because of the safety inplications and because a sound technical basis for the change exists, ti.e commitment made to close the containment isolation valves durin-g an SB0 event has been modified as allowed under 10CFR50.59.
l The enclused justification addresses the safety implications in more detail and delineates the relevant exclusion criteria for the valves identified in our review.
The justification outlines our position on CIV exclusion criteria for the postulated SB0 at GGNS and is provided for your l
information.
The change will be reported unoce the provisions of I
10CFR50. 59(b) (2).
If you have any questions or require additional information concerning this matter, please call Bill Brice at (601) 437-6556.
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attachnent: Justitication for CIV Exclusions for Postulated SB0 at GGNS
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GNRO-93/00003 Page 3 of 4
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cc Mr.
P., H. Bernhard (w/a) l Mr. D. C. Hintz (w/a)
Mr. R. B.
.eGehte (w/a)
Mr. N.'S. Reynolds (w/c) j-Mr. H. L. Thomas (w/o)
Mr. Stewart D.-Ebneter (w/a)
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Regional Administrator j'
U.S. Nuclear Regulatory-Commission l
Reglon II j
101 Marietta St.,
N.W., Suite 2900 Atlanta.. Georgia-30323 i
l Mr. P. W. O' Conner, Project Manager (w/2)
Office of Nuclear Reactor Regulation i
U.S. Nuclear Regulatory Commission i-Mail Stop 13H3 i
Washington, D.C.
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Attachment to GNP,0-93/00003 Page 1 of 4 i
JUSTIFICAT10ti FOR CIV EXCLUSIONS FOR POSTULATED SB0 AT GGNS J
RCIC Isolation Valves That May Need To Be Operated To Cope The following Reactor Core Isolation Cooling (RCIC) valves may need to be j
operated to cope with an SB0 at GGhS:
VALVE NUMBER PENETRATION VALVE CESCRIPTION ESA-F063 17 RCIC STEAM SUPPLY E51-F064 17 RCIC STEAM SUPPLY E51-F031 28 RCIC SUPP POOL SUCTION E51-F068 29 RCIC TURBINE EXFAUST Valves E51-F031 and F068 are powered f rom Division I battery 1A3. Durir.3 an SB0 event as postulated for GGNS (i.e. 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />), these valves will have functional control room porLtion indication and are capable of being cycled from the control room.
Thm dCIC steam supply line isolation valves (E51-F063 and F064) ara normally opened during operation at 100% power (es is assumed by the GGNS SB0 scenario). On a loss of AC power the steam supply valves will fall as-is (open) which will alloe the supply of steum required to operate the RCIC turbine.
Although E51-F063 and F064 do not meet the two additional exclusion criteria, RCIC can and should be utilized as long as it is benefic 2al in accordance with the c_Tergency procedures.
HPCS Valves That May Need To Be Operated To Cope The following High Pressure Core Spray system (HPCS) valves may need to be ope-ated to cope with an SB0 at GGNS:
VALVE NUMBER PENETRATION VALVE DESCRIFFION 1
E22-F015 25 HPCS SUPP POOL SUCTION E22-F004 26 HPCS INJECTION E22 "023 27 HPCS TEST RETURM E22-F012 27 HPCS MIN FLOW 1
The E22-F015 E22-F023 and E22-F012 valves meet the following criteria:
a) connect directly to the suppression pool b) are provided with a single isolation valve c) are always submerged thereby preventing escape of containment atmosphtre d) the piping outside containment constitutes a closed system providing a second isolat.icn barrier following a single active failure Additionally, the E22-F023 and E22-F012 valves are normally closed and are part of a loop that is net expected to be breached during an SBO.
G9211121/SNLICFLR - 5 a
i Attachment to GWRO-93/00003 Page 2 of 4 All 13sted HPCS valves receive AC power from the Division III emergency 4
diesel generator which can be assumed to be functional during the SB0 event postulated for GGNS.
Additionally, closure of any of the aforementioned RCIC or HPCS valves l
would be in conflict with the requirements of BWROG Emergency Procedure Guidelines Rev. 4 Appendix B to which GGNS is committed.
The guideline Statesi l
Procedures developed from these emergency procedure j
guidelines specify symptomatic operator actions which will maintain the reactor plant in a safe condition and optimize plant response and margin to safety irrespective of the initiating event. HowcVer, for certain specific events (e.g., earthquake, tornado, blackout, or fire),
4 emergency response and recovery can be further enhanced by additional auxilia'/ event-specific procedures intended i
for use in conjunction with the symptomatic procedurec.
As with action specified in any other procedure intended for use with the symptomatic procedures, these event-specific ooerator actions must not contradict or subvert the symptomatic operator actions specified in the l
symptomatic procedures and must not result in loss or unavailability of equipment the operation of which ir j
specified in these procedures.
Valves That Are Designed To Be Open During Accident Conditions And/Or Do Not Receive Closure Signals The following valves are designed to be open during accident conditions and/or do not receive closure signals on containment isolation:
VALVE NUMBER PENFTRATION VALVE DESCRIPTION E12-F004A 12 RHR A SUPP POOL SUCTION E12-F004B 12 RHR 3 SUPP POOL SUCTION E12-F004C 13 RHR C SUPr POOL SUCTION i
E12-F027A 20 RHR A INLET TO CONTAINMENT E12-F027B 21 RHR B INLET TO CONTAINMENT E12-F024A 23 RHR A TEST RETURN E12-F024B 67 RHR B TEST RETURN E12-F023 24 RHR C TEST RETURN E12-F064A 23 RHR A MIN FLOW E12-F064B 67 RHR B MIN FLOW E12-F064C 24 RHR C MIN FLOW E21-F001 30 LPCS SUCTION I
E21-F011 32 LPCS MIN FLOW E21-F012 32 LPC3 TEST RETURN G9211121/5NLICFLR - 6
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Attachment to GNRO-43/00003 Page 3 of 4 All of these valves except for E12-F027A and B meet the following criteria:
9 a) connect directly to the suppression pool b) are provided with a single isolation valve i
c) are always submerged thereby preventing the escape of containment atmosphere
.i d) the piping outside containment constitutes a closed system providing a second isolation barrier following a single active failure The E12-F027A and B are normally open but are bounded by normally closed j
MOVs and manual valves located in containment.
Tae bounding valves are required by system operating instructions to be closed during normal l
operation at all times (except for brief intervals during testing) and are expected to remain closed during an SBO.
(Valves E12-F064 A. B and C have 4
already been excluded per NUMARC 87-00 criteria because of their associated check valve.)
Other than E12-F021, closure of the valves in this list could also bc in conflict with the requirements of BVROG Emergency Procedure Guidelines Rev.
4 Appendix B as referenced earlier. All low pressure ECCS injection / spray systems and both loops of RHR suppression pool cooling could be rendered unr+allable by closing these valves.
Valves Closed During Normal Operations The following valves are required by system operating instructions (SOIs) to be closed during normal operation at all times (except for brief intervals during testing) and are expected to remain closed during an SB0 (position indication is available for these valves in the control room prior to the SBO):
VALVE NUMBER PENETRATION VALVE DESCRIPTION E12-F011A 23 RHR HX A DISCHARGE To SUP POOL E12-F011B 67 RHR HX B DISCHARGE TO SUP POOL P45-F273 60 AUX FLOOR / EQUIP DRAIN TANKS TO SUP POOL P45-F274 60 AUX FLOOR / EQUIP DRAIN TANKS TO SUP POOL G33-F034 43 RWCU TO CONDENSER Valves of Concern The following valves are open during-normal operations and will fail as-is (open) during an SBO.
These valves are accessible and will be closed manually using the valve operator handwheel, or will be verified closed using local position indication in the event of imminent core damage during 4
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0 Attachment to GNRO-93/00003 Page 4'of 4 j
a SB0 event.
Procedure 05-1-02-I-4 Loss of A" Power,-will be revised to l
Implement these changes. The containment isolation valves of concern are h
VALVE NUMBER PENETRATION VALVE DESCRIPTION 1
B21-F019 19 IN STEAM LINE DRAIN i
G41-F029 58 FPCCU FROM UPPER CONTAINHENT POOL G33-F039 83 RWCU TO FEEDWATER l
G33-F004 87 RWCU PUMP SUCTION G33-F054 88 RWCU PUMP DISCHARGE l
Exclusions of CIVs per NUMAhC 87-00 guidance have previously been submitted and are unchanged by this rcvision.
This revision has been reviewed to ensure that this justification does not conflict with previous SB0 CIV i
j justifications for GGNS.
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