ML20196B351
| ML20196B351 | |
| Person / Time | |
|---|---|
| Issue date: | 11/24/1998 |
| From: | Rossi C NRC OFFICE FOR ANALYSIS & EVALUATION OF OPERATIONAL DATA (AEOD) |
| To: | Ralph Beedle, Chexal V, Hastie W, Lochbaum D, Towsend D ELECTRIC POWER RESEARCH INSTITUTE, GENERAL ELECTRIC CO., INSTITUTE OF NUCLEAR POWER OPERATIONS, NUCLEAR ENERGY INSTITUTE (FORMERLY NUCLEAR MGMT &, UNION OF CONCERNED SCIENTISTS |
| Shared Package | |
| ML20196B356 | List: |
| References | |
| NUDOCS 9812010084 | |
| Download: ML20196B351 (14) | |
Text
_ . . .
j S C'og ye ?% UNITED STATES 8 5 E NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 s *****/ tbverber 24,1998 Mr. William J. Hastie Institute of Nuclear Power Operations 700 Galleria Paikway Atlanta, GA 30339-5957
Dear Mr. Hastie:
SUBJECT:
REQUEST FOR REVIEW OF SPECIAL REPORT - GENERAL ELECTRIC REACTOR PROTECTION SYSTEM UNAVAILABILITY, 1984-1995 (DRAFT 2) !
Attached for your information and review is the draft report on the General Electric reactor protection system (RPS) unavailability at U.S. commercial boiling water reactors. This study is part of our ongoing evaluaSn of the reliability of risk-significant safety systems. Using data obtained from licensee event reports and the Nuclear Plant Reliability Data System (NPRDS),
the study provides an estimate of the associated system unavailability based on actual and test
)
demands between 1984 and 1995 and identifies dominant contributors to potential system '
unavailability. The report also includes a comparison with RPS reliability estimates published in probabilistic risk assessments (PRAs) and individua! plant examinations (IPEs), and an evaluation of the most significant trends. 1 This is the first major evaluation of the reliability of the General Electric RPS by the NRC since the mid 1980s when NRC developed simple RPS logic models in support of the anticipated transient without scram rulemaking activities. A major contribution of this current study is the !
collection of common cause failure (CCF) data relat?d to the RPS.
Major findings from this study are the following:
e The mean unavailability of the General Electric RPS was estimated to be 3.8 x 104 The lower 5* percentile and upper 95* percentile values are 7.5 x 10 and 1.1 x 104, respectively. There were no complete failures of the reactor protection system during the period of 1984 through 1995.
- Essentially 100% of the RPS unavailability is from CCF events. The independent failures k contribute less than 0.1%. CCFs of the hydraulic control units (HCUs) and backup scram solenoid operated valves (SOVs) contribute 50% to total system unavailability, channel relay and trip unit CCF events contribute 39%, control rod CCF events contribute 7%, and trip system relay CCFs contribute 4%. The requirement to test 10% of the control rods ,Y every four months was a significant factor in detecting CCF events before they became
'O more significant by causing complete failures of larger numbers l
,...r_3a C[N) 9812010084 981124 %
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. W. Hastia 9 o Tha backup scram portion of th3 RPS is an important contributor to the RPS reliability.
How:vsr, tha backup scram SOVs are not safety-related equipment and, therefore, are not part of the NPRDS reportable scope. Their failure characteristics were assumed to be similar to the HCU SOVs. In addition, since there are not any surveillance test requirements for these backup SOVs, this study assumes that they are tested every refueling outage. (A sensitivity analysis without credit for the backup scram function resulted in an increase from 3.8 x 104 to 4.6 x 104for RPS unavailability).
e The RPS mean unavailability estimates in IPEs range from approximately 1.7 x104 to 8.6 x 10 4 However, most of the IPE studies referenced the NUREG-0460 RPS unavailability of 3 x 10 4 RPS quantification models in IPEs are generally limited in ;
c Scope.
- The trends in time of RPS component failure probabilities and the number of CCF events are generally flat over the study period. There are no indications of performance degradation or improvement in these components over the period of 1984 through 1995. I 1
In accordance with our peer review process prior to the distribution of the final report, we want l to provide you with the opportunity to review and comment on the draft report. We are l specifically interested in your comments regarding the technical adequacy of the modeling and ;
data analysis and the appropritteness of the major findings and conclusions of this study. To l meet our planned publication schedule, we would appreciate receiving your comments within 30 days from receipt of this letter.
As you may know, the Office for Analysis and Evaluation of Operational Data studies do not represent an official U.S. Nuclear Regulatory Commission position or the position of the responsible NRC program office. Our reports are one input to an ongoing review and evaluation process.
! A copy of this draft report and letter are being placed in the Public Document Room at 2120 L Street NW, Washington, DC 20555.
If you have any questions related to this report, please contact Mr. Hossein Hamzehee (301-415-6228) (e-mail: hgh@nrc. gov) of my staff.
Sincerely, Original signed by Charles E. Rossi, Director Safety Programs Division l Office for Analysis and Evaluation of Operational Data
Enclosure:
As stated Identicalletters sent to: See attached list Distribution: See attached list DOCUMENT NAME: H:\HGH\GE-OUT.WPD
- See previous concurrence To receive a copy of thes document, indecate in the box "C" = Copy wo/ attach /enck *E's Copy w/attacNencls "N" s No copy
^
OFFICE RRAS/RRAB E RRAS/RRAB E RRAB E SPD C NAME HHamzehee* SMays* PBaranowsky* CERo h [
DATE 11/9/98 11/10/98 11/10/98 ///g/98 OFFICIAL RECORD COPY
- W. Hastie /
- o The backup scram portion of the RPS is an important contributor to the RPS reliability. However, the backup scram SOVs are not safety-related equipment and, therefore, are not part of the '
NPRDS reportable scope. Their failure characteristics were assumed to be similar to the F)dU SOVs. In addition, since there are not any surveillance test requirements for these back SOVs, this study assumes that they are tested every refueling outage. (A sensitivity analysis ithout 4
credit for the backup scram function resulted in an increase from 3.8 x 10 to 4
4.6 x 10 for RPS unavailability).
e The RPS mean unavailability estimates in IPEs range from approximately 1.7 04 to 8.6 x 10d, However, most of the IPE studies referenced the NUREG-0460 S unavailability of 3 x 10'5 RPS quantification models in IPEs are generally limited in scop i e The trends in time of RPS component failure probabilities and the nu er of CCF events are i generally flat over the study period. There are no indications of pe rmance degradation or l improvement in these components over the period of 1984 throu 1995. i in accordance with our peer review process prior to the distributio f the final report, we want to provide ,
l you with the opportunity to review and comment on the draft rep We are specifically interested in '
your comments regarding the technical adequacy of the mode 'ig and data analysis and the l appropriateness of the major findings and conclusions of thi study. To meet our planned publication schedule, we would appreciate receiving your comments ithin 30 days from receipt of this letter. A copy of the draft report is also being provided to other v dors for information only. l As you may know, the Office for Analysis and Eval tpftion of Operational Data studies do not represent an official U.S. Nuclear Regulatory Commission posjtfon or the position of the responsible NRC program office. Our reports are one input to an ongoing teview and evaluation process.
p A copy of this draft report and letter are bei placed in the Public Document Room at 2120 L Street NW, Washington, DC 20535.
If you have any questions related to tf s report, please contact Mr. Hossein Hamzehee (301-415-6228) (e-mail: hgh@nrc. v) of my staff.
Sincerely, l
l l Charles E. Rossi, Director Safety Programs Division Office for Analysis and Evaluation of Operational Data
Enclosure:
As stat d l Identica! 6iters:
l Mr. V 's. Chexal, rector
, Mr. Ralph E. Beedle Mr. William J. Hastie Nucear Safety alysis Center Nuclear Energy Institute Institute of Nuclear Power Operations F_tectric Power esearch Institute Electric Power Research Institute 700 Galleria Parkway l
P.0, Box 10 2 P.O. Box 10412 Atlanta, GA 303390-5957 Palo Alto, A 94303 Palo Alto, CA 94303 Mr. Dav' A. Lochbaum Nucle Safety Engineer Distribution:
Uni of Concemed Scientists RRAB RF SPD RF AEOD RF File Center Public 16, 6 P Street NW, Suite 310 DRasmuson DHickman JRosenthal DEDE JMitchell Washington, DC 20036-1495 DOCUMENT NAME: H:\HGH\GE-OUT.WPD
- see previous concurrence To receive a copy of this document, Indicate in the box: "C" a Copy wo/ attach /encts "E" = Copy wlattachlencls "N" s No copy OFFICE RRAS/RRAB E RRAS/RRAB E RRAB E SPD NAME HHamzehee* gly SMays"hM PBaranowskyk CERossi DATE 11/9/98 11/10/98 11/10/98 / /98 i OFFICIAL RECORD COPY l
u
- t.
Identicalletters sent to: l l
Mr. V.K. Chexal, Director - !
. Nuclear Safety Analysis Center = l Electric Power Research Institute-P.O. Box 10412 ~
- Palo Alto, CA 94303 Mr. Ralph E: Beedle -
Nuclear Energy Institute 1776 i Street NW, Suite 400 Washington, DC 20006-3708 Mr. David A. Lochbaum Union of Concemed Scientists )
1616 P Street NW, Suite 310 -
. Washington, DC 20035-1495 Distribution w/ encl.:
File Center -
Public :
Distribution w/o encl.:
RRAB R/F SPD R/F TTMartin DRasmuson DHickman JRosenthal AThadani, RES MKnapp, DEDE JMitchell, OEDO ,
2 1
I l
I
- 1. g oa ato yi k UNITED STATES j,
j t
NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555 0001 k.'.... tbverter 24,1998 Mr. Ralph E. Beedle l
Nuclear Energy Institute l 1776 l Street NW, Suite 400 I Washington, DC 20006-3708
Dear Mr. Beedle:
l
SUBJECT:
REQUEST FOR REVIEW OF SPECIAL REPORT - GENERAL ELECTRIC l 1
REACTOR PROTECTION SYSTEM UNAVAILABILITY, 1984-1995 (DRAFT 2) I 1
Attached for your information and review is the draft report on the General Electric reactor i protection system (RPS) unavailability at U.S. commercial boiling water reactors. This study is l I
part of our ongoing evaluation of the reliability of risk-significant safety systems. Using data obtained from licensee event reports and the Nuclear Plant Reliability Data System (NPRDS), j the study provides an estimate of the associated system unavailability based on actual and test l demands between 1984 and 1995 and identifies dominant contributors to potential system )
unavailability. The report also includes a comparison with RPS reliability estimates published in !
probabilistic risk assessments (PRAs) and individual plant examinations (IPEs), and an i evaluation of the most significant trends. l This is the first major evaluation of the reliability of the General Electric RPS by the NRC since the mid 1980s when NRC developed simple RPS logic models in support of the anticipated transient without scram rulemaking activities. A major contribution of this current study is the ;
collection of common cause failure (CCF) data related to the RPS. ;
l Major findings from this study are the following:
1 4
- The mean unavailability of the General Electric RPS was' estimated to be 3.8 x 10 . The
- 4 lower 5* percentile and upper 95* percentile values are 7.5 x 10 and 1.1x 10 , I respectively. There were no complete failures of the reactor protection system during the i period of 1984 through 1995.
- Essentially 100% of the RPS unavailability is from CCF events. The independent failures contribute less than 0.1%. CCFs of the hydraulic control units (HCUs) and backup scram solenoid operated valve (SOVs) contribute 50% to total system unavailability, channel relay and trip unit CCF events contribute 39%, control rod CCF events contribute 7%, and trip system relay CCFs contribute 4%. The requirement to test 10% of the control rods every four months was a significant factor in detecting CCF events before they became more significant by causing complete failures of larger numbers of redundant components.
l I
. R. Beedle e The backup scram portion of the RPS is an important contributor to the RPS reliability.
However, the backup scram SOVs are not safety-related equipment and, therefore, are not part of the NPRDS reportable scope. Their failure characteristics were assumed to be similar to the HCU SOVs. In addition, since there are not any surveillance test requirements for these backup SOVs, this study assumes that they are tested every refueling outage. (A sensitivity analysis without credit for the backup scram function resulted in an increase from 3.8 x 104 to 4.6 x 10 4for RPS unavailability).
e The RPS mean unavailability estimates in the IPEs range from approximately 1.7 x 10* to 8.6 x 10" However, most of the IPE studies referenced the NUREG-0460 RPS unavailability of 3 x 10'8 RPS quantification models in IPEs are generally limited in scope.,
e The trends in time of RPS component failure probabilities and the number of CCF events are generally flat over the study period. There are no indications of performance degradation or improvement in these components over the period of 1984 through 1995.
In accordance with our peer review process prior to the distribution of the final report, we want to provide you with the opportunity to review and comment on the draft report. We are specifically interested in your comments regarding the technical adequacy of the modeling and data analysis and the appropriateness of the major findings and conclusions of this study. To meet our planned publication schedule, we would apprecia'.e receiving your comments within 30 days from receipt of this letter.
As you may know, the Office for Analysis and Evaluation of Operational Data studies do not represent an official U.S. Nuclear Regulatory Commission position or the position of the responsible NRC program office. Our reports are one input to an ongoing review and evaluation process.
A copy of this draft report and letter are being placed in the Public Document Room at 2120 L Street NW, Washington, DC 20555.
If you have any questions related to this report, please contact Mr. Hossein Hamzehee (301-415-6228) (e-mail: hgh@nrc. gov) of my staff.
Sincerely, bharle h
Rossi, Director Safety Programs Division Office for Analysis and Evaluation of Operational Data l
1 '
Enclosure:
As stated s
- "Og
[ k UNITED STATES
!* 1.L j NUCLEAR REGULATORY COMMISSION i ^C WASHINGTON. 0.C. 20555-0001
~
% *...# Novatber 24,1998 Mr. V.K. Chexal, Director Nuclear Safety A.nalysis Center Electric Power Research Institute P.O. Box 10412 Palo Alto, CA 94303 Lear Mr. Chexal:
SUBJECT:
REQUEST FOR REVIEW OF SPECIAL REPORT - GENERAL ELECTRIC REACTOR PROTECTION SYSTEM UNAVAILABILITY, 1984-1995 (DRAFT 2)
Attached for your information and review is the draft report on the General Electric reactor protection system (RPS) unavailability at U.S. commercial boiling water reactors. This study is l part of our ongoing evaluation of the reliability of risk-significant safety systems. Using data l obtained from licensee event reports and the Nuclear Plant Reliability Data System (NPRDS), I the study provides a estimate of the associated system unavailability based on actual and test demands between 1984 and 1995 and identifies dominant contributors to potential system l unavailability. The report also includes a comparison with RPS reliability estimates published in I probabilistic risk assessments (PRAs) and individual plant examinations (IPEs), and an I evaluation of the most significant trends.
This is the first major evaluation of the reliability of the General Electric RPS by the NRC since j the mid 1980s when NRC developed simple RPS logic models in support of the anticipated '
transient without scram rulemaking activities. A major contribution of this current study is the i collection of common cause failure (CCF) data related to the RPS. l Major findings from this study are the following:
1 1
e The mean unavailability of the General Electric RPS was estimated to be 3.8 x 104 The i lower 5* percentile and upper 95* percentile values are 7.5 x 10'7 and 1.1 x 104, respectively. There were no complete failures of the reactor protection system during the period of 1984 through 1995.
- contribute less than 0.1%. CCFs of the hydraulic control units (HCUs) and backup scram l solenoid operated valves (SOVs) contribute 50% to total system unavailability, channel relay and trip unit CCF events contribute 39%, control rod CCF events contribute 7%, and l l trip system relay CCFs contribute 4%. The requirement to test 10% of the control rods
! every four months was a significant factor in detecting CCF events before they became more significant by causing complete failures of larger numbers of redundant components.
l l
, V.K. Chexal e The backup scram portion of the RPS is an important contributor to the RPS reliability.
However, the backup scram SOVs are not safety-related equipment and, therefore, are not part of the NPRDS reportable scope. Their failure characteristics were assumed to be similar to the HCU SOVs. In addition, since there are not any surveillance test requirements for these backup SOVs, this study assumes that they are tested every refueling outage. (A sensitivity analysis without credit for the backup scram function resulted in an increase from 3.8 x 104 to 4.6 x 104for RPS unavailability).
e The RPS mean unavailability estimates in IPEs range from approximately 1.7 x 10 4 to 8.6 x 10". However, most of the IPE studies referenced the NUREG-0460 RPS 4
unavailability of 3 x 10 . RPS quantification models in IPEs are generally limited in
- scope, e The trends b time of RPS component failure probabilities and the number of CCF events are generam, riat over the study period. There are no indications of performance degradation or improvement in these components over the period of 1984 through 1995.
In accordance with our peer review process prior to the distribution of the final report, we want to provide you with the opportunity to review and comment on the draft report. We are specifically interested in your comments regarding the technical adequacy of the modeling and data analysis and the appropriateness of the major findings and conclusions of this study. To meet our planned publication schedule, we would appreciate receiving your comments within 30 days from receipt of this letter.
As you may know, the Office for Analysis and Evaluation of Operational Data studies do not represent an official U.S. Nuclear Regulatory Commission position or the position of the responsible NRC program office. Our reports are one input to an ongoing review and evaluation process.
A copy of this draft report and letter are being placed in the Public Document Room at 2120 L Street NW, Washington, DC 20555.
If you have any questions related to this report, please contact Mr. Hossein Hamzehee (301-415-6228) (e-mail: hgh@nrc. gov) of my staff.
Sincerely, bharles E. bs( Ross,,)
i Director Safety Programs Division Office for Analysis and Evaluation of Operational Data
Enclosure:
As stated s
-. . . . _ . . - . . - .~. - - - . - . - . . - - . . - . , ._. - ~ -. . . - . .
pR Qto
[ ?+2 UNITED STATES l j
, t NUCLEAR REGULATORY COMMISSION o WASHINGTON, D.C. 20555-0001
- Novenber 24,1998 Mr. David A. Lochbaum Nuclear Safety Engineer Union of Concerned Scientists 1616 P Street NW, Suite 310 Washington, DC 20036-1495
Dear Mr. Lochbaum:
SUBJECT:
REQUEST FOR REVIEW OF SPECIAL REPORT- GENERAL ELECTRIC REACTOR PROTECTION SYSTEM UNAVAILABILITY, 1984-1995 (DRAFT 2)
Attached for your information and review is the draft report on the General Electric reactor protection system (RPS) unavailability at U.S. commercial boiling water reactors. This study is part of our ongoing evaluation of the reliability of risk-sign;ficant safety systems. Using data obtained from licensee event reports and the Nuclear Plant Reliability Data System (NPRDS),
the study provides an estimate of the associated system unavailability based on actual and test demands between 1984 and 1995 and identifies dominant contributors to potential system unavailability. The report also includes a comparison with RPS reliability estimates published in probabi;istic risk assessments (PRAs) and individual plant examinations (IPEs), and an evaluation of the most significant trends.
This is the first major evaluation of the reliabilty of the General Electric RPS by the NRC since the mid 1980s when NRC developed simple RPS logic models in support of the anticipated transient without scram rulemaking activities. A major contribution of this current study is the collection of common cause failure (CCF) data related to the RPS.
Major findings from this study are the following:
- The mean unavailability of the General Electric RPS was estimated to be 3.8 x 104 The lower 5* percentile and upper 95* percentile values are 7.5 x 10 and 1.1 x 104 ,
respectively. There were no complete failures of the reactor protection system during the period of 1984 through 1995.
e Essentially 100% of the RPS unavailability is from CCF events. The independent failures contribute less than 0.1%. CCFs of the hydraulic control units (HCUs) and backup scram 4
solenoid operated valves (SOVs) contribute 50% to total system unavailability, channel relay and trip unit CCF events contribute 39%, control rod CCF events contribute 7%, and trip system relay CCFs contribute 4%. The requirement to test 10% of the control rods every four months was a significant factor in detecting CCF events before they became more significant by causing complete failures of larger numbers of redundant components.
1 9
D. Lochbaum
However, the backup scram SOVs are not safety-related equipment and, therefore, are l not part of the NPRDS reportable scope. Their failure characteristics were assumed to be similar to the HCU SOVs. In addition, since there are not any surveillance test l requirements for these backup SOVs, this study assumes that they are tested every refueling outage. (A sensitivity analysis without credit for the backup scram function resulted in an increase from 3.8 x 104 to 4.6 x 104 for RPS unavailability).
- The RPS mean unavailability estimates in IPEs range from approximately 1.7 x 104 to 8.6 x 10". However, most of the IPE studies referenced the NUREG-0460 RPS unavailability of 3 x 10 4 RPS quantification models in IPEs are generally limited in scope. ,
e The trends in time of RPS component failure probabilities and the number of CCF events are generally flat over the study period. There are no indications of performance degradation or improvement in these components over the period of 1984 through 1995.
In accordance with our peer review process prior to the distribution of the final report, we want to provide you with the opportunity to review and comment on the draft report. We are specifically interested in your comments regarding the technical adequacy of the modeling and data analysis and the appropriateness of the major findings and conclusions of this study. To meet our planned publication schedule, we would appreciate receiving your comments within 30 days from receipt of this letter.
As you may know, the Office for Analysis and Evaluation of Operational Data studies do not represent an official U.S. Nuclear Regulatory Commission position or the position of the responsible NRC program office. Our reports are one input to an ongoing review and evaluation process.
A copy of this draft report and letter are being placed in the Public Document Room at 2120 L Street NW, Washington, DC 20555.
If you have any questions related to this report, please contact Mr. Hossein Hamzehee (301-415-6228) (e-mail: hgh@nrc. gov) of my staff.
Sincerely,
[$
bharles E. Rossi, Di
! Safety Programs Division
( Office for Analysis and Evaluation of Operational Data
Enclosure:
As stated i
p* *
- c yq 5 UNITED STATES j
$\u ig .p J
j NUCLEAR REGULATORY COMMISSION WASHINGTON. 0.C. 20555-0001
, Noveter 24, 1998 Mr. Dennis Townsend General Electric Nuclear Energy Owners Group G.E. Nuclear Energy 175 Curtner Avenue M/C 187 San Jose, CA 95125
SUBJECT:
REQUEST FOR REVIEW OF SPECIAL REPORT - GENERAL ELECTRIC REACTOR PROTECTION SYSTEM UNAVAILABILITY,1984-1995 (DRAFT 2)
I
Dear Mr. Townsend:
Attached for your information and review is the draft report on the General Electric reactor protection system (RPS) unavailability at U.S. commercial boiling water reactors. This study is part of our ongoing evaluation of the reliability of risk-significant safety systems. Using data obtained from licensee event reports and the Nuclear Plant Reliability Data System (NPRDS).
the study provides an estimate of the associated system unavailability based on actual and test demands E; tween 1984 and 1995 and identifies dominant contributors to potential system unavailability. The report also includes a comparison with RPS reliability estimates published in probabilistic risk assessments (PRAs) and individual plant examinations (IPEs), and an evaluation of the most significant trends.
This is the first major evaluation of the reliability of the General Electric RPS by the NRC since the mid 1980s when NRC developed simple RPS logic models in support of the anticipated transient without scram rulemaking activities. A major contribution of this current study is the collection of common cause failure (CCF) data related to the RPS.
Major findings from this study are the following:
e The mean unavailability of the General Electric RPS was estimated to be 3.8 x 10 4 The lower 5"' percentile and upper 95* percentile values are 7.5 x 10 and 1.1 x 104 ,
respectively. There were no complete failures of the reactor protection system during the period of 1984 through 1995.
- Essentially 100% of the RPS unavailability is from CCF events. The independent failures contribute less than 0.1% CCFs of the hydraulic control units (HCUs) and backup scram solenoid operated valves (SOVs) contribute 50% to total system unavailability, channel relay and trip unit CCF events contribute 39% control rod CCF events contribute 7%, and trip system relay CCFs contribute 4% The requirement to test 10% of the control rods every four months was a significant factor in detecting CCF events before they became more significant by causing complete failures of larger numbers of redundant components.
Ma D. Townsend . o The backup scram portion of the RPS is an important contributor to the RPS reliability.
l However, the backup scram SOVs are not safety-related equipment and, therefore, are not part of the NPRDS reportable scope. Their failure characteristics were assumed to be similar to ths HCU SOVs. In addition, since there are not any surveillance test requirements for these backup SOVs, this study assumes that they are tested every refueling outage. (A sensitivity analysis without credit for the backup scram function resulted in an increase from 3.8 x 104 to 4.6 x 10* for RPS unavailability).
- The RPS mean unavailability estimates in IPEs range from approximately 1.7 x 104 to 8.6 x 10". However, most of the IPE studies referenced the NUREG-0460 RPS unavailability of 3 x 104 . RPS quantification models in IPEs are generally limited in scope.
e The trends in time of RPS component failure probabilities and the number of CCF events are generally flat over the study period. There are no indications of performance degradation or improvement in these components over the period of 1984 through 1995.
In accordance with our peer review process prior to the distribution of the final report, we want to provide you with the opportunity to review and comment on the draft report. We are specifically interested in your comments regarding the technical adequacy of the modeling and data analysis and the appropriateness of the major findings and conclusions of this study. To meet our planned publication schedule, we would appreciate receiving your comments within 30 days from receipt of this letter. A copy of the draft report is also being provided to other vendors for information only.
As you may know, the Office for Analysis and Evaluation of Operational Data studies do not represent an official U.S. Nuclear Regulatory Commission position or the position of the responsible NRC program office. Our reports are one input to an ongoing review and evaluation process.
A copy of this draft report and letter are being placed in the Public Document Room at 2120 L l Street NW, Washington, DC 20555.
If you have any questions related to this report, please contact Mr. Hossein Hamzehee (301-415-6228) (e-mail: hgh@nrc. gov) of my staff.
I Sincerely, -
Original signed by Charles E. Rossi, Director Safety Programs Division Office for Analysis and Evaluation l of Operational Data l
Enclosure:
As stated l cc w/ encl.: See attached list Distribution w/o encl.: See attached list DOCUMENT NAME: H:\HGH\RPS-GE.WPD
- see previous concurrence
- To receNe a copy of this document. Indicate in the bor
- "C" a Copy wo/ attach /encle "E" a Copy w/ attach /encle "N" a No copy
[ OFFICE RRAS/RRAB C RRAS/RRAB C RRAB C SPD (~
NAME HHamzehee/nl* SMays* PBaranowsky* CERog6f f
DATE 11/9/98 11/18/98 11/18/98 ///1c /98 OFFICIAL RECORD COPY
D. Towns:nd /
o The backup scram portion of the RPS is an important contributor to the high RPS reliability. However, the backup scram SOVs are classified as non-safety and, there re, are not part of the NPRDS reportable scope. Their failure characteristics are ass ed to be similar to the HCU SOVs. In addition, since there are not any surveillance te requirements for these backup SOVs, this study assumes that they are teste every refueling outage. (A sensitivity analysis without credit for the backup scra unction resulted in an increase from 3.8 x 10* to 4.6 x 10* for RPS unavailability e The RPS mean unavailability estimates in IPEs range from approxim ety 1.7 x 10* to 8.6 x 10" However, most of the IPE studies referenced the NURE -0460 RPS
, unavailability of 3 x 10* RPS quantification models in IPEs are enerally limited in scope.
e The trends in time of RPS component failure probabilities a the number of CCF events are generally flat over the study period. There are no indi tions of performance degradation or improvement in these components over e period of 1984 through 1995.
In accordance with our peer review process prior to the di ribution of the final report, we want to provide you with the opportunity to review and comm it on the draft report. We are specifically interested in your comments regarding the echnical adequacy of the modeling and data analysis and the appropriateness of the finding and conclusions of the study. To meet our planned publication schedule, we would appreciat receiving your comments within 30 days from receipt of this letter. A copy of the draft re ort is being provided to them for information only.
As you may know, the Office for Analysis d Evaluation of Operational Data studies do not represent an official U.S. Nuclear Regula ry Commission position or the position of the responsible NRC program office. Our r ports are one input to an ongoing review and evaluation process.
A copy of this draft report and lett are being placed in the Public Document Room at 2120 L Street NW, Washington, DC 20 5.
If you have any questions rel ted to this report, please contact Mr. Hossein G. Hamzehee (301-415-6228) (e-mail: hg @nrc. gov) of my staff..
Sincerely, Charles E. Rossi, Director Safety Programs Division Office for Analysis and Evaluation of Operational Data Enclosure- stated cc w/ encl.: ee attached list Distributi w/o encl.: See attached list DOCUMENT NAME: H:\HGH\RPS-GE.WPD To r.c.iv. 4opy or this docum.nt,indic.t. in th. bon: c . copy oiattacni.nci. e Copy w/ attach /encls N* = No copy OFF)dE RRAS/RRAB C RRAS/RRAB C RRAB C SPD N[ME HHamzehee/nl pg SMays 4.a PBaraNYsd[ CERossi
[DATE / /98 Il / lt /98 // / /) /98 / /98 OFFICIAL RECORD COPY l
D.Townsend l cc w/ encl.:
Mr. Andrew Drake, Project Manager Westinghouse Owners Group .
Westinghouse Electric Corporation i Mail Stop ECE 5-16 P.O. Box 355 Pittsburgh, PA 15230-0355 Mr. J. J. Kelly, Manager B&W Owners Group Services Framatome Technologies, Inc.
P.O. Box 10935 Lynchburg, VA 24506-0935 ABB Combustion Engineering Owners Group c/o Gordon Bischoff, CEO.G Project Manager M.S. 9615-1932 2000 Day Hill Road Windsor, CT 06095 Distribution w/ encl.:
File Center Public Distribution w/o encl.
RRAB RF SPD RF DRasmuson DHickman JRosenthal TTMartin AThadani, RES MKnapp, DEDE JMitchell, OEDO
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