ML20246G118
| ML20246G118 | |
| Person / Time | |
|---|---|
| Issue date: | 02/13/1989 |
| From: | Advisory Committee on Reactor Safeguards |
| To: | Advisory Committee on Reactor Safeguards |
| References | |
| REF-GTECI-070, REF-GTECI-094, REF-GTECI-NI, TASK-070, TASK-094, TASK-70, TASK-94, TASK-OR ACRS-2621, NUDOCS 8905150191 | |
| Download: ML20246G118 (10) | |
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SUMMARY
/ MINUTES OF THE ACRS SUBCOMMITTEE ON MECHANICAL COMPONENTS JANUARY 27,1989 BETHESDA, MARYLAND
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The ACRS Subcommittee on Mechanical Components met on January 27, 1989 in Room 422 at Bethesda, Maryland to review the NRC Staff's proposed resolution to Generic Issues 70, " Power Operated Relief Valve & Block Valve Reliability," and 94, " Additional Low Temperature Overpressure Protection for Light Water Reactors."
Notice of the meeting was published in the Federal Register on January 17, 1989, (Attachment A). The schedule of items covered in the meeting is in Attachment B.
A list of handouts kept with the office copy of the minutes is included in Attachment C.
There were no written or oral statements received or presented from members of the public at the meeting.
E. G. Igne was Cognizant ACRS Staff Member for the meeting.
Principal Attendees ACRS NRC g
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C. Michelson, Chairman K. Kniel o
C. Wylie, Member R. Baer J. Carroll, Member R. Kirkwood C. Siess, Member E. Throm osu)
F. Cherny 56 G. Mazetis (So/
Others
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W. McCaughey, BG&E c01N B. Gore, PNL G. Murphy, ORNL DESIGNATED ORIGINAL Certified By
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Miputes/ Mechanical Components 2
Mtg., January 27, 1989 Highlights F. Cherny, RES, discussed the proposed resolution to Generic Issue 70, "PORV and Block Valve Reliability."
F. Cherny briefly highlighted the history, described air actuated valves, and electrical actuated valves and discussed where/how PORVs and block valves are installed in PRWs in domestic nuclear power plants.
He stated that these valves are mainly used in PWRs as pressurizer safety and relief valves.
Historically PORVs used during pre-1979 licensed plants were not safety grade. That is, valve operators and their electrical control systems were normally designed to non-safety related standards. However, the pressure-retaining elements of PORVs are within the reactor coolant pressure boundary (RCPB) and were constructed to the same codes and~
standards as those required for similar safety-related RCPB components.
PORVs originally provided for operational flexibility. The role of PORVs has changed over a period of time and that they are now relied upon by many Westinghouse, B&W and CE plants to perform one or more of the following safety-related functions:
Mitigating a design basis steam generator tube rupture accident.
Provide low-temperature overpressure protection of the reactor vessel during start-up and cooldown.
Venting of the reactor coolant system.
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Minutes / Mechanical Components 3
Mtg., January 27, 1989 They also provide safety-related functions for events beyond the design j
basis, such as feed and bleed and ATWS mitigation.
Operating experience of PORVs and block valves is documented in an ORNL i
report NUREG/CR - 4692. The report reviewed events from 1971 to mid-1986. About 198 PORVs (mechanical, control or design) were found degraded or failed.
23% of the PORV mechanical events and 67% of the PORV control events were failures.
A PRA risk reduction study was done by BNL and reported in NUREG/CR -
4999. Results indicate that core melt frequencies attributable to PORV or block valve failures were found to be relatively insignificant and to represent only a very small fraction of total core melt frequency attributable to internal plant events. The NRC staff believes that"the BNL results underestimates safety benefit that would be achieved by improving PORV and block valve reliability.
However, BNL fault trees are dominated by operator error considerations, and it does not appear that results would have changed a great deal even if higher PORV failure rates were used. Consideration of feed and bleed (not within the scope j
of the BNL study, but evaluated as part of USI A-45) indicates a much greater safety importance of PORVs and block valves..
F. Cherny in the resolution of GI-70 recommends the following changes:
o For future PWR plants and plants currently under construction;
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Minutes / Mechanical Components 4
Mtg., January 27, 1989 when PORVs and block valves are used for safety functions, these components should be classified as safety-related and a minimum of two PORVs and block valves be installed.
o For generating plants, a number of improvements (short of upgrading to fully safety-grade hardware) can increase re-liability of PORVs and block valves and provide assurance that they will function as required. These improvements are as follows:
Include PORVs and block valves within the scope of Appendix B.
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For most operating plants, modify the limiting conditions-of operation of PORVs and block valves in the Technical Specifications for Modes 1, 2 and 3.
The intent is to ensure plants that run with the block valves closed ~
maintain electrical power to the block valves so they can be opened upon demand and not permit unlimited plant operation with PORVs and block valves inoperable for other reasons other than seat leakage.
Use to the extent possible, more reliable PORV block valve designs that are resistant to failure.
In the supporting regulatory analysis, the NRC staff estimates that outage avoidance costs based on industry data reported by EPRI, would
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Minutes / Mechanical Components 5
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Mtg., January 27, 1989 far exceed the cost of implementing the staff's recommendations (except for the last item above).
2.
E. Throm, RES, discussed the. proposed. generic resolution GI-94,
" Additional Low-Temperature Overpressure Protection (LTOP) for LWRs." This study was performed by Battelle Pacific Northwes' Laboratory (PNL) under B. Gore.
E. Throm stated that in 1979, multi-plant Action B-04 resulted in the imposition of new requirements for procedures and equipment to reduce the potential for cold overpressure events based on recommendations from USIA-26.
Current staff requirements are in SRP 5.2.2 and Tech. Spec. for Overpressure protection. Basis for LTOP are found in GDC 15 and 31 of Appendst A and Appendix G to 10 CFR Part 50.
Operating history indicates that only three (3) overpressure mit-igating system failures occurred, e d that the frequency of LTOP events is about the same as previously observed before'1980 or about 0.1/ reactor-years. Also stated was that the likelihood of exceeding Appendix G pressure / temperature limit is about 1 in 10 per LTOP event.
A vessel through-wall crack probability anaifsis e s,erformed. Results indicate that a core damage frequency (CDF) for E w+.nghouse and Combustion Engineering Nuclear Steam Supply System is about 3.24 x 10-6/ reactor-year. For a B&W plant, the mean CDF is negligible and no l
LTOP transient was observed to challenge the overpressure mitigating 1
system.
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6-Minutes / Mechanical Components Mtg., January 27,;1989 Lf.1 Based on conse,ences analyses performed, the NRC staff stated that a g
Technical Specification only change is recommended to improve the overpressure mitigation system, and-that'no haroware changes are necessary.
J L.-
Subcommittee Action l.
The subcommittee in its deliberation will recommend to the ACRS at the February _ meeting that";iis proposed Generic Issues 70 and 94 be accepted with' clarifying comments for GI 70.
NOTE:
A transcript of the meeting is available at the NRC Public
-Document, Gelman Bldg., 2120 "L" St. NW., Washington, D.C.,
Telephone (202) 634-3383 or can'be purchased from Heritage Reporting Corporation,1220 L Street,- NW., Washington D.C.-
20005, Telephone (202) 628-4888.
9 i
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.ATTACHMEN,A
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Federal Register / Vol. 54. No.10 / Tuesday Ja,.nt.ary 17.1989 / Notfoes
~~1805 -
The entire meeting will be open to -
a The proposed action is in accordance nonradiological environmental impacts j
with the licensee's application dated associated with the proposed public attendance.
The agenda for the subject meeting amendment.
August 30.1988
- h*II b* ** I*II***;
The Needfor the Pmposed Action Alternative to the Pmposed Action Th ursday. January 26.1989-8:30 a.rn.
The proposed changes are needed so Since the staff concluded that there untilthe conclusion ofbusiness The Subcommittee will review the that the licensee can use higher are no significant environmental effects Human Factors Research Program Plan.
enrichment fuel and provide the thai would result from the proposed Oral statements may be presented by flexibility of extending the fuel action, any alternatives with equal or irradiation and permitting operation of gica ter environmentalimpacts need not members of the public wth the be evaluated.
concurrence of the Subcommittee longer fuel cycles.
The principal alternative would be to Chairman; written statements will be Envimamentallmpacts of the Proposed deny the requested amendment.This accepted and made available to the Action The staff has completed its evaluation [mpa t of plan o re on an ould ont ing those io f e emiti educed operational flexibility, meeting when a transcript is being kept, and questions may be asked only by e hnica Speci cat ns proposed Alternative Use of Resourcee rnembers of the Subcootnittee.its revision would permit use of fuel This action does not involve the use of consultants and Staff. Persons desiring enriched with Uranium 235 up to 4.85 any resources not previously considered t make ral statements should notify weight percent.The safety In the TinalEnvironmentalStatement the ACRS staff member named below as considerations associated with reactor.
operation with higher enrichment and related to the operation of the Beaver far in advance as is practicable so that extended irradiation have been Valley Power Station. Unit 2." dated 8pproMak arrangements can b snade.
evaluated by the NRC staff.The staff September 1985*
During the initial portion of the' meeting. the Subcommittee, along with has concluded that such changes would Agencies andPersons Consulted any of its consultants who may be not adversely afIcct plant safety.The The NRC staff reviewed the license #s present, may exchange preliminary proposed changes have no adverse effect on the probability of any accident. request and did not consult other views regardin8 matters to be The increased burnup may slightly agencies or Persor.s.
considered dunng the balance of the change the mix of fission products that Finding of No Significant Impact meeting.
The Subcommittee will then hear might be released in the event of a The staff has determined not to presentations by and hold discussions serious accident but such small changes prepare an environmentalimpact with representatives of the NRC staff.Its would not significantly affect the statement for the proposed license consultants, and other interes,ted 2 consequences of serious accidents.No amendment.
persons regarding this review.
changes are being made in the types or Based upon the foregoing Further information regarding topics amounts of any radiologicaleffluents environmental assessment, the staff to be discus, sed. whether the meeting that may be released offsite during concluded that the proposed action wilj has been cancelled or rescheduled, the normal operation.There is also no not have a significant effect on the Chairman's ruling on requests for the significant increase in the allowable quality of the human environment.
opportunity to present oral statements individual or cumulative occupational For further details with respect to this and the time allotted therefor can be radiation oposure.
action, see the application for obtained by a prepaid telephone call to With regard to potential nonradiologicalimpacts of reactor amendment dated August 30.1988, the cognizant ACRS staff member.Mr.
operation with higher enrichment and which is available for public inspection Herman Alderman (tolephone 301/492-estended irradiation, the proposed at the Commission's Public Document 7750) between 7:30 a.m. and 4:30 p.m.
Room, the Gelman Building. 2120 L Persons planning to attend this meetin8 changes to the TS involve systema Street. NW., Washington, DC and at the are urged to contact the ebove named located within the restricted area as B F. Jones hiemorial Library. 663 individual one or two days before the defined in 10 CFR Part 20.They do not Franklin Avenue. A!Iquippa.PA 15001.
scheduled meeting to be advised of any affect nonradiological plant eff!uents and have no other environmental Dated at Rockvitle. Maryland, this 9th day changes in schedule, etc., which may impact.
of January.1989.
have occurred.
The environmentalimpacts of For the Nuclear Regulatory Commission.
Date: January 9.1989, transportation resulting from the use of p,,,, g*.g. m.
NONW a
higher enrichment fuel and extended Actins &metor.Pmject &metomie M Assistont Ex ecutive Directorfor Pwject irradiation have been discussed in the DMsion (Reactor fmiects WH, qfierof Beview.
l staff assessment entitled."NRC NuclearRecctorBegulation.
lFR Doc.89-909 Filed 1-1b89; B5$ am) lFR Doc.84-006 Filed 1-1Feo;845 am)
Ifec s f ra sp r t ult g from Extended Fuel Enrichment and Irradiation." dated July 7.1988 (53 FR Advisory Committee on Reactor 30355). As indicated therein, the Advtsory Committee on Reactor Safeguards Subcommittee on environmental cost contribution of the Safeguards Meeting of the Mechanical Components; Meeting proposed increase in the fuel enrichment Subcommittee on Human Factors; and irradiation limits are either Meetin8
"'he ACRS Subcommittee on hiechanical Components will hold a unchanged or may in fact be reduced The ACRS Subcommittee on lluman meeting on january 27.1989. Room P-from those summarized in Table S-4 as Factors will a meeting on January 28.
422.7920 Norfolk Avenue.Bethesda, set forth in 10 CFR 51.42(c).
1989. Room p-422.7920 Norfolk Avenue.
Therefore. the staff concludes that MD.
there are no significant radiological or Bethesda. MD.
j 1806-Federal Register / Vol. 54, 'No.10 / Tuesday. January 17, 1989 / Notices The entire meeting will be open to 422,7920 Norfolk Avenue. Bethesda.
(Docket No. 50-315)
~
1 public attendance.
MD.
indlana Michigan Power Co.;
I The agenda for subject meetin8 shall The ent. ire meeting will be open to Consideration of lasuance of g,, g public attendance.
Amendment to Facility Operating Triday fonvory27. JGBA2:00p.m.
until the conclusion ofbusiness The age La for the subject meeting License and Proposed No Significant The Subcommittee will review the will be as followe; Hazards Consideration Determination and Opportunity for Hearing proposed tesolution of Generic issues Friday, fonuary 27,1989-B:30 a.m.
until Wp.m.
The United States Nuclear Regulatory e
r ture sur Prote t on.,,
The Subcommittee will review the Commission (the Commission)is and other related matters.
adequacy of the proposed Staff's plans consideringissuance of an amendment members of the public with the to implement the recommendations to Facility Operating License No. DPR-Oral statements may be presented by 58 issued to the Indiana Michigan Power c:ncurrence of the Subcommittee resuldng from the Fire Risk Scoping Company (the licensee), for operation of Chairman; written statements will be Study.
accepted and made available to the Oral statements may be presented by C, Conclea{"Nnt M na Committee. Recordings will be permitted members of the public with the ofnt '
cia 8
g" rd ith the 11 cnly durin those portinns of the concurrence of the Subcommittee 8 ept.
Chairman; written statements will be appli$on for am ndmentYated k
P'
"' "Nion naybe a ke nd b
a cepted and made available to the August 9,1988, the amendment would e-n perm M aHow a ondme extension oMe mem ers of the Subcommittee,its consultants, and staff. Persons desiring nly dunng those portions of the surveillance intervals for certain to make oral statements should notify meeting when a transcript is being kept, surveillance normally performed with the ACRS staff member identified below and questions may be asked only by the unit shutdown.The extensions as far in advance as practicable so that members of the Subcommittee,its involve:
2 appropriate arrangements can be made.
consultants, and Staff. Persons desiring
- 1. lce basket weighing:
3 During the initial portion of the to make oral statements should notify
- 2. lce condenser flow passage meeting, the Subcommittee, along with the ACRS Staff member named below inspections; eny of its consultants who may be as far in advance as is practicable so
- 3. Ice condenser inlet door testing: and I
vizws regarding matters to be that appropriate arrangements can be
- 4. Resistance temperature detector l
pr:sent, may exchange preliminary calibrations, considered during the balance of the
- made, Prior to issuance of the proposed meeting.
During the initial portion of the hcenn ameeede h%n The Subcommittee will then bear meeting, the Subcommittee, along with will have made findings required by the presentations by and hold disecesions any Iits consultants w.ho may be Atomic Energy Act of 1954, as amended I
withirpresentatives of the NRC Staff, present, may exchange preliminary (the Act)and the Commission's its c:nsultants, and other interested views regarding matters to be regulations.
d persons regarding this review.
c naidered during the balance of the The Commision has made a proposed I
. Further information regarding topics to be discussed, whether the meeting meeting.
determination that the amendment has been cance!!ed or rescheduled, the The Subcommittee will then hear request involves no significant hazards
[
Chairman's ruling on requests for the presentations by and hold discussions consideration. Under the Commission's opportunity to present oral statements with representatives of the NRC Staff, regulations in 10 CFR 50.92, this means b
that operation of the facility in p
and the time allotted therefor can be its consultants, and other interested accordance with the proposed y
cbtzined by a prepaid telephone call to persons regarding this review.
amendment would not (1) involve a C
the cognizant ACRS staff member, Mr.
Further information tegarding t pics sigmlicant increase in the probability or g
Elpidio Igne (telephone 301/492-8192) to be discussed, whether tne meeting consequences of an accident previously C
between 7:30 a.m. and 4:15 p.m. Persons has been cancelled or rescheduled, the evaluated; or (2) create the possibility of pisnning to attend this meeting are Chairman's ruling on requests for the a new or different kind of accident from p
urged to contact the above named opportunity to present oral statements any accident previously evaluated; or (3) individual one or two days before the and the time allotted therefor can be involve a significant reduction in a scheduled meeting to be advised of any obtained by a prepaid telephone call to margin of safety, B
ch:nges in schedule, etc., which may the cognizant ACRS Staff member, Mr.
The Commission's evaluation of the B i bzve occurred.
Sam Duraiswamy (telephone 301/492-proposed amendment with respect to the DMe: lanuary B. MB9.
9522) between 7:30 a.m. and 4:15 p.m.
above criteria is as follows:
4l.
Morton W. ubarkin.
n
- fg"8 Criterlon s si tantEsecutive DirectorforProject The period of time the surveillance
[ g l individual one or two days before the intervals will be exended is very brief.
g,
[TR Doc.89-987 Filed 1-1b80. B.45 am]
scheduled meeting to be advised of any The surveillance for which extensions in changes in schedule, etc., which may are requested fall due from February 26.
have occurred.
1989, through March 26,1989. Extensions g;;
Advisory Committee on Reactor Date: January 9.1989.
are necessary only until the Cycle 10.11
, to
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refueling outage, which la scheduled to Safeguards Subcommittee on Auxitlary Morton W, Ut>arkh, f g begin in March 1989.The licensee has tnd Secondary Systems; Meeting Ex ecutive Dirretorfor Project Review, reviewed previous surveillance test i,, af
' er The ACRS Subcommittee on Auxiliary cnd Secondary Systems will hold a jFR Doc. as-ma, Filed t-theo; &45 am]
results for the affected equipment and y
has found nothing that would indicate y:
meeting on january 27,1989 Room P-owo coos neo ow f..
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-6 ATTACHMENT B C. Michelson', Chairman 3
3 TENTATIVE SCHEDULE ACRS SUBCOMMITTEE ON MECHANICAL' COMPONENTS MEETING-JANUARY 27, 1989 7920 NORFOLK AVENUE, BETHESDA, MARYLAND, ROOM P-422 l
i 8:30 - 8:40'a.m.
-Opening Remarks C. Michelson, Chairman j
io,2 6 8:40 - 4G+GO a.m.
Generic Issue 70; " Power Operated Relief j
Valve & Block Valve Reliability" i
R. Kirkwood, RES t
t h' 7 b ". l L, I D D
10.00 - 10:15 a.m.
BREAK ---------
to:4o - ix c D 4065-N.m.
General Issue 94; " Additional Low Temperature Overpressure Protection for Light Water l
Reactors" E. Throm, RES
\\ : :.:J ~ 12.: 05 t1:30 12 S NOON Subcommittee Discussion and Adjournment 1
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ATTACHMENT C 1.-
9 LIST OF HANDOUTS 1.
Presentation to ACRS Subcommittee Mechanical Components Generic Issue 70 PORY.and Block,Yalve Reliability by Senior Task Mgr. R. Kirkwood, EIB and Presentation by F. Cherny, Section Leader EIB 2.
Generic Issue 94 " Additional Low-Temperature Dyerpressure Protection (LTOP) for LWRs" by Edward D. Throm, Senior Task Manager
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