ML20006A319
| ML20006A319 | |
| Person / Time | |
|---|---|
| Issue date: | 01/11/1990 |
| From: | Tam P Office of Nuclear Reactor Regulation |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| TAC-40577, NUDOCS 9001260118 | |
| Download: ML20006A319 (11) | |
Text
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,M, W
- y (.,
January 11, 1990
( -
NUMARC (Nuclear Utility Management
' ORGANIZATION:
andResourceCouncil)
W
SUBJECT:
Neeting Summary - Meeting of December 15, 1989 onStationBlackoutIssues(TAC 40577)
REFERENCE:
Meeting Notice, P.S. Tam to J.F. Stolz, December 6, 1989 t
The meeting was held as specified in the referenced notice.
It was a sequel to the. meeting dated November 8,1989 (see summary by P.S. Tam, dated
- i. November 22,1989). is a list of meeting attendees.
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The staff (chief spokespersons: J. Sniezek, f. Miraglia, A. Thadani and F. Rosa), stated that (1) it appreciated NUMARC's comments dated November 21, 1989 on the draft generic letter, (2) in view of NUMARC's efforts to issue augrented guidence, a generic letter will not be issued at this time, and (3) NUMARC should instead communicate the staff's concerns to all licensees.
1he NUMARC communication to the licensees should be "such as to elicit licensee confirmation that the SB0 analyses were conducted in accordance with the guidance of RC 1.155 and guidelines of NUMARC 87-00,lts of and that the original (or revised) SB0 response acwrately presents the resu analyses performed and is supported by technically sufficient documentation."
The staff's detailed cornnents on NUMARC's Novcaber,1989 letter are documented in Enclosures f and 3.
The staff reittrated that the approach chosen to handle station blackout (i.e., working closely with NUMARC to develop mutually acceptable guidance and to define the scope of required actions by licensses and the staff) was intended to save both NRC and industry resources.
NUMARC (chief spokesperson W. Rasin), stated that a final augmented guidance document, taking into account the staff's comments in Enclousres 2 and 3 and related discussions, will be prepared in the near future and issued to licensees.
NUMARC would like the staff to expeditiously concur with the final version of this document before issuing it to the industry.
Original signed by Peter S. Tam, Senior Project Manager i,
Project Directorate 1-4 Division of Reactor Projects - 1/11
Enclosures:
As stated 1
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SUMMARY
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ST ATION BLACKOUT i
Peeting With NUttARC December 15, 1989
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12/15/89 NRC/NUMARC CON 4ENTS/ POSITION ON SB0 AUDITS ISSUES (REFERENCE DRAFT G.L. DATED 10/24/S9 AND NUMARC A. MARION LEIIER TO MRC (A. THADANI) DAlED 11/21/89)
ISSUE (REF. ENCLOSURE 1 TO MUMARC LETTER)
NUMARC POSITION NRC POSITION 1.
(General Comments) Approach (1)NUMARCwillissue (1) Concurs generally that for clarification of 5B0 clarification. MRC NUMARC should issue guidance to industry should not issue G.L.
clarification. The MtMARC casuminication to the industry should be such as to elicit licensee confirmation that the 580 analyses were conducted in accordance with the guidance of RG 1.155 and guidelines of NUMARC A7-00, and that the original (or revised) 580 response accurately presents the results of analyses per-formed and is supported by technically sufficient 4
documentation.
2.
(Item 1)
Improper determination NUMARC will issue Concurs with staff of SB0 duration clarification approval.
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3.
(Item 2) Use of remote shutdown (1) NUMARC has not taken a (1) We believe that abandonment S capability, ev6cuation of the definite position on of control room may be a S
control room.
whether the control generic problem 1.e., other Q room should remain plants in addition to the functional and manned 2 plants audited may be N
during an 580, there-abandoning control rooms to fore, they do not think conserve battery capacity, it is a generic problem.
and this concern should be
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ISSUE (REF. ENCLOSURE 1 TO NUMARC LETTER)
NUMARC POSITION NRC POSITION i
casmunicated to the industry. Our position is that control room should be maintained operable during and through the recovery phase of an 500.
4.
(Item 3) Instances where licensees NUMARC to advise utilities that Staff concurs with NUMARC's have misapplied / misinterpreted they need to consider providing approach.
NUMARC 87-00 methodology MRC with additional information to previously furnished in the generic rule response.
50 (Item 4) Licensees taking MUMARC believes that this Staff agrees; we have not improper credit for hurricane concern is limited to only checked all the 580 responses shutdown procedures to reduce one plant.
to confirm it.
SB0 required duration i
6.
(Item 5) Use of existing EDGs NUMARC states that this concern Staff agrees with NUMARC's as AAC and meeting single is adequately addressed by cri-clarification on this issue.
failure criteria terion B.8.e of MUMARC 87-00.
7.
(Item 6) Departures from NUMARC position is that the Staff concurs with NtMARC methodology in MUMARC 87-00; licensees should identify position.
credit taken for assumptions, and address these items and calculations and analyses for verify that they apply to SB0 coping assessment their plants.
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3-ISSUE (REF. ENCLOSURE 1 TO MUMARC LETTER)
NUMARC POSITION NRC POSITION 8.
(Item 7) Operability of NUMARC position is that the Staff agrees except for areas equipment in dominant areas equipment operability must below 120*F, the cabinet doors of concerns (DAC) (i.e.,
be established for areas need to be opened within half-120*F) and nondominant above 120*F and for areas hour to 4-.ure equipment areas of concern (
120*F) below 120*F, it is assumed operabi '
that equipment operability exists and no further action is needed.
9.
(Item 8) Commitment to establish NUMARC believes that it is Staff position is that an EDG EDG reliability in accordance with premature to commit to an reliability program in accord-RG 1.155, Section C.1.2 EDG reliability program ance with RG 1.155 Position until B-56 issue is resolved.
C.I.2 and MUMARC 87-00 Appendix D is a requirement of the 580 rule package and should be committed to at this time.
Aay more specific guidance re-l sulting from resolution of U-56 i
will be implemented separaly.
- 10. Enclosure 2, "NUMARC 87-00 See Enclosures 2 and 3 A copy of Enclosures 2 and 3 Supplemental Questions and have been marked to reflect staff Answers," and Enclosure 3, positions.
"NUMARC 87-00: Assumptions,"
of the NUMARC letter i
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utilities by NUMARC. Each assumption on the list should be reviewed to assure F,
applicability to individual plants.
dk RECTION 2r RENERAL CRITERIA AND BASELINE AS$tMPTIONS p
2.5 Reactor Coolant Inventory loss 2.1 Q: Must the assumed 25gpa reactor coolant pump seal leak rate be used by all plants (8WR and PWR)?
A:
No.
It is acceptable to NRC to use 18gpm for BWR recirculation n
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Leakage rates lower than 25 gpa for PWRs or 18 gpm for BWRs may be z.
pumps.
used, provided a justification exists and the NRC is informed that lower
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rates are being utilized.
1.7 Effects of Lost Ventilation P
2.1 Q:
Is it necessary to provide reasonable assurance of equipment C gl operability in dominant areas of concern where temperatures are below 120F7 A:
The need to establish reasonable assurance of equipment operability t
applies only to dominant areas of concern. 5.tR Section 2.7.1 of NUMARC 87-(F
- 00. A dominant area of concern (DAC) exists when, based on documented D'
enaineerina iudaement areas containing station blackout response equipment
') j have substantial heat generation terms and lack of adequate heat removal systems due to the blackout. ing NUMARC 87-00, p. 7-18.
If temperatures in the OAC are calculated to be equal to or less than 3
120 degrees F, this establishes reasonable assurance of equipment operability
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without further analysis.
If temperatures in the OAC are calculated to be in excess of 120 degrees F, reasonable assurance of equipment operability must be provided. NUMARC 87 00, Appendix F, and its accompany topical i
W f, report provide acceptable methods for assuring equipment opera g ity. j gi For the control r ion,eventhoughitmaynotmeettheOACcriteria,a heatup analysis shou 1(be documented to demonstrate that temperatures do not exceed 120 degrees F.f !f temperatures exceed 120F, reasonable assurance of station blackout response equipment operability must then be provided. NUMARC 87-00, Appendix. F, and its accompanying topical report provide methods for assuring equipment operability.
For additional information, refer to Question / Answer Nos. 4, 6, and 82 from the Responses to Questions Raised at the NUMARC 87-00 Seminars (NUMARC, October,1988).
2.3 Q:
May masonry, sheet metal or gypsum walls be assumed as heat sinks in the NUMARC 87-00 room heatup calculations?
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$ECTION 3:
M OUIRED CDPING DURATION CATEGORY I
3.2. Part 10. Evaluatina Indonendence of Off-site Power Evstan l
i 3.1 Q:
How quickly must manual transfers be made, when evaluating the independence of off site power systems (! Group)?
j A:
Any manual method of transferring power sources for all safe shutdown buses is acceptable providing the transfer can be accomplished in a reasonable time, such as less than one hour. Thus, a manual transfer involving operation of a disconnect link requiring several hours to complete M.not S. acceptable.
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3.2 Q:
How independent must switchyards be for the purp,ose of I Group determinations?
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A, p. 3 11 of NUMARC 87-00 requires A:
A 'no" answer to Criteri that multiple switchyards must be electrically independent. Electrical independence can be provided by normally open breakers p tween switchyards gg gh psiu) '
l or busses.
3.3 Q:
Where normal AC power is provided by the unit main. cenerator and only one of two safe shutdown buses is automatically or manually transferred to preferred or alternate off-site sources, does that qualify as a transfer i
of all safe shutdown buses?
A:
No. &}.1 safe shutdown buses must be transferred per Criteria B(1) l and8(2),p.3-11,ofNUMARC8700.
1 3.2.2. Part 2.B Determine the N=har of Necessary EAC Standby Power Systems 3.4 Q:
When determining the number of EAC standby power sources necessary to operate safe shutdown equipment, what safe shutdown loads should be g
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A: VSafe shutdown 1'oads may be determined from the plant's design basis V
shutdown loads following a loss of off site power (LOOP).
3.5 Q:
Does safe shutdown mean cold shutdown?
A:
No. The plant should be brought to the desion basis safe shutdown condition, which may be hot standby, hot shutdown, or cold shutdown.
3.6 Q:
At a multi unit site, if an EAC source is used as an AAC source, should that EAC/AAC source be excluded from the number of EAC standby power supplies used to determine the blacked out unit's EAC Group?
A:
Yes. An AAC source which is also an EAC source must be subtracted from the number of EAC sources available as EAC standby power supplies. To do otherwise would be double counting as discussed in NUMARC 87-00, p. 3-14.
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SECTION 4:
STATION BLACK 0UT RESPONSE M DCEDURES l
4.2.1 Station Blackout Resoonse Guidelinen 4.1 Q:
Is it acceptable to dispatch an operator from the control room to l
the remote shutdown panel for the purpose of providing power from the Appendix R diesel or the safe shutdown facility?
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A:
Yes. However, the control room should not be abandoned.
It is anticipated that recovery from a station blackout may require operator action i
or monitoring from the control room.
$ECTION 7:
COPING WITH A STATION BLACK 0UT EVENT l
7.1 Q:
When ensuring containment integrity, can normally closed valves be excluded from consideratinn similar to valves normally Inded closed during operation per NUMARC 87 00, Section 7.2.5, Step 1 (1).
l A:
No. A normally closed valve may not be considered to be a normally locked closed valve unless scw action is taken to prevent valve operation.
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Such actions would include removing control power fuses or racking out breakers supplying power to motor operators.
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APPENDIX B:
ALTERNATE AC POWER CRITERIA 4
8.1 Q:
What single failure considerations are applicable at a multi unit site where EAC sources are utilized for AAC7 l-A:
When a Class IE emergency AC (EAC) source is used as an AAC source, a single failure is applied to one of the EAC power sources in the non blacked-out unit.
If the remaining EAC source meets the criteria of NUMARC 87-00 Appendix B, AAC power is assumed to be available to the blacked-out unit.
Refer to NUMARC 87-00, p. 2-2 through 2 4.
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8.2 Q:
What single failure considerations are applicable to SB0 AAC power systems?
A:
Per Criterion B.8.e of NUMARC 87-00, the AAC power source must not be susceptible to a single point vulnerability whereby a likely weather related event or single active failure could disable any portion of the onsite emergency AC power sources or the preferred (offsite) power sources, and simulanteously fail the AAC power source. Random failures other than the type addressed by Criterion B.8.e are not contemplated and need not be considered.
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As stated in NUMARC 87 00 Section 1.3, it is important that utilities verify that baseline assumptions are applicable to their plants. Chapter 2 4
of NUMARC 87-00 discusses baseline assumptions; however, other chapters include additional assumptions, as well. Many assumptions are verified in the cours b'
of performing the various coping calculations, but some assumptions require i
specific verification.
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The rigor to be applied by licensees in verifying assumptions is stated 4
in Question / Answer 3 of Responses to Questions Raised at the NUMARC 87 00
-e Seminars (October 1988): ' utilities are not expected to perform rigorous j
analyses or evaluations in verifying the assumptions of NUMARC 87 00."
[5,i. nil _ i@[EES3ji/5$15?i!!iiU!1IMUGI 3
Listed below are major assumpuoiis which in some cases have not been satisfactorily verified. Preceding each assumption is the number of the applicable NUMARC 87 00 section.
i 2.4.l(1) The event ends when AC power is restored to shutdown busses from any source. To support AC power restoration it will be necessary to close breakers. This can be done either manually or electrically via DC power. For those utilities utilizing DC power, the ability to 3
close breakers at the end of the blackout should be included in the s
L battery calculation. The first available power source can be an EDG; therefore flashing of the EDG field should also be included in the calculation.
2.5.2 Reactor coolant pump seal leakage is assumed not to exceed 25 It is recognized that BWRs do not have reactor coolant gpm per pump.
pumps; however recirculation pump leakage should be evaluated. The NRC staff has indicated that 18 gpm is an acceptable assumed leakage rate for BWR recirculation pumps. BWRs/PWRs taking credit for lower leakage rates should have documentation to support use of the lower rates.
2.7 Loss of ventilation effects.
2.7.1 Temperatures resulting from loss of ventilation are enveloped by LOCA and HELB profiles. LOCA/HELB transients dump large amounts of energy into a containment in a short time, thus, this assumption may seem intuitive. However, LOCA/HELB analyses assume fans and coolers are operating. During SBO, containment fans and coolers may not be available. This assumption, therefore, should be verified.
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