ML19309D565
| ML19309D565 | |
| Person / Time | |
|---|---|
| Site: | Crystal River, Crane  |
| Issue date: | 10/04/1979 |
| From: | Jerome Murphy, Taylor M NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES) |
| To: | Rowsome F NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES) |
| Shared Package | |
| ML19309D561 | List: |
| References | |
| ACRS-1684, NUDOCS 8004100521 | |
| Download: ML19309D565 (12) | |
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.i OCT 4 1979 9
MDOUL".DuM FOR:
Frank H. Rowsome. Acting Director Probabilistic Analysis Staff. RES l
FROM:-
J. A. Murphy Probabilistic Analysis Staff. RES M. A. Taylor Probabilistic Analysis Staff. RES i
1
SUBJECT:
IREP - IRITIAL PUL'tT STUDT I
As requested, we have attempted to develop a general framework for the conduct of a lint *ad risk assessment of a B&W reactor aimed at identifying any unique rist-impacting sequences relative to the Reactor. Safety Study.
An absolute detemination of risk is not intanded. Tentatively, we have selected Crystal River 3, a plant owned and operated by Florida Power Corporation, for analysis.
l The architect-engineer for this Sabcock and Wilcox reactor was Gilbert Associates.
It began comercial operation in March 1977.
The project, as presented in Figure 1. will require the following tasks:
1.
A survey of the LER files as now established in ORtu. and A0 reports, as well as the Sandia and Fluor-Zion systems interactions studies to identify interactions and conaan mode failuru which have occurred in similar plants. This survey should precee constmetion of systen logic models and event trees stree it will ensure that actual experience is incorporated into the assessment perfomed.
1.
Event trees for loss-of-coolant accidents and transient conditions.
Specific attention will be given to more frequent LOCAs and thesa will include a feedwater transient tree which incorporates experience at E1W plants and will explore the post-TMI modifications. Emphasis will be given toward understanding the human coupling interaction between systems at the event tree sequence level.
3.
Fault trees for the key systems identified in the event trees. Tney will be constructed to the component level and will include control, actuation.
and electric power considerations.
human errors will be included as well as the ability of the operator to cope in the time span available. Our preliminary' opinion is that staplified fault trees will be required for
-- the following systems: auxiliary feedwater and secondary staan relief, high pressure emergency core cooling in the injectica and recirculation modes, low pressure emergency core cooling in both injection and recirculation l modes. containment spray and containment heat removal systems and a l
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.N 11mitad study of. loss of AC power, probably done in detail for the 430 and 4160 busses and the emergency diesel generators. with limited analysis of high voltage switchyard faults. Separate fault trees will probably be
, required for ECCS and AFWS initiation logic and the system trees must include the contribution from auxiliary systems such as instrument air.
ventilation, component cooling, etc., and control-induced failures.
Trunca*on of the fault trees will be pemitted provided a written basis is provided. This basis will present the rationale why no coupling of i
cutsets is expected from further development of the tree.
4.
An investigation of the adequacy of high pressure-low pressure interfaces.
i Acquisition of an appropriate data base for component failure rates and l
5.
human errors. At the present time it sm advisable to request that Bill Yesely update the RSS data base as required to reflect the data This would include a tabular presentation of analyzed in his programs.
It should be recognized that utilization of human error failure rates.
an updated data base will significantly complicate any meaningful comparison of the results with WASH-1400.
Quantification of the fault trees and event trees using error propagation C.
It may be desirable to separately perfom sensi-to tne extent necessary.
tivity analyses to demastrate the effect of various distributions on systec:
error bounds.
7.
Analysis of the physical phenomena associated with dominant sequences to obtain estimates of the magnitude of releases from the containment. This will aid in categorizing releases into appropriate release categories.
To conduct a program of this magnitude in a short time period, delays associated with acquiring and transferring information must be minimi:ed.
Optimally, the event tres and fault tree analysts should share a coconn location during the initial portion of the project.
(A. Garcia has indicated space can be made available at the Air Rights Building for approxistely 12 persons.) As the fault trees progress below the top logic, however, the analysts should be located at or near the rite with innediate access to as-built drawings and Frucedures as well as a representative of the plant operations staff. This will permit verification of engineering and procedural details and will minimize information transfer and print reproduction. Access should also be arranged between the fault tree analysts at the site, the remaining team in Bethesda.
the architect-engineer, and the vendor. Such an arrangement will be costly and will require considerable efforts on the part of upper management to solicit the support of all parties involved.
In addition to basic plant data. deterministic calculations my be required to
- understand the behavior of the plant under off-normal conditions. This may also involve real-time simulation at an appropriate simulator to the extent The arrangements with the vendor should cover this possibility and possjble.
l it may be desirable to have confirmatory calculations made by one of the MAC contractors (e.g.
IrJ.L) on a selected basis.
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3 Frank E. Rowsome As previously notied, accurate sequence catego To expedita the preparaticin of a final report, tedhnical writing, graph and proofreading support would be most helpful.and directio l
presented.
Assuming the analysis is perfomed over a four-month,perieC the fol resources are considered necessary:
Event trees and contractor direction - M. Taylor, J. Ibrphy essential full-time with review by either J. Curry, P. Baranowsky, or M. Cuar.ing 1.
on a 25 percent part-time basis.
Fault trees - At least eight analysts chosen from the following:
2.
EGAG EI Sandia_
SAI E
L. Conradi
- 5. Asselin J. Kelly M. Fedele M. Stewart J. Young G. Colb A. Garcia A. Giacobbi
- 5. Atkinson G. Soyd D. Leaver W. Cramond P. Wood F. Leveren:
Fault tree review - J. Pittman, F. Hanning essentially half-time.
3.
Fault and event tree quantification - At least two of the following:
Tnese E. Lofgren, R. Liner, J. h,.cs (all SAI), W. Yesaly, F. Hanning.
4.
w111 be required full-time over a two-month period.
Accident analysis - R. Wsoten, P. Cybulskis on an on-call consultant 5.
basis.
Peer review by KRR - Periodic review and consultatio E.
of the following:
In addition. it would be desirable to IL Rabin. W. Lcfava, W. Minners. include specific IE personnel suc training personnel on an as-oceded basis.
Quantification review - F. Goldberg and W. Yesely approxianta 7.
over a two-acath period.
Considering the cost of rented space at the si PAS effort will be approximately 1.4 person-years this snart-tern program.
over this four conth period.
We envision a compilation The nature of the final report needs to be detamined.a D**0
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with deterministic reconmendations suitable for licens Mditional infom.ation Standard Raview Plan and Standard Technical Specifications.
will be generated which could benefit PAS studies and operator, staff, and I
inspector training.
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J. A. Nurphy Probabilistic Analysis Staff Office of Nuclear Regulatory Research i
H.
Taylor Probabilistic Analysis Staff Office of naclear Regulatcry Research J
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I FIGURE 1 ANALYSIS OF EVENT TREE 4
ACCIDENT CONSTRUCTION PROCESSES AS NEEDED 1.F.R SURVEY PU % TOGETilER EXISTING INFO ALREADY COMPILED V
Y CATEGORIZATION LICENSING y
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FAULT TREE 4
Q H 8
OF EVENT CONSTRUCTION RECOHHENDATIONS 1
TREE SEQUENCES DETERHINISTIC, CALCULATIONS BY VENDOR AS HEEDED, ANALYSIS OF IIIGil PRESSURE -
SUtetARY REPq OF RESULTl LOW PRESSURE INT.
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NRR AND PEER REVIEW,
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ENCLOSURE B 4
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1 MIDLAND UNIT 1 SysteWCanponent Design Component Component Construction Completed Procurement Fabrication Completed
(%) (182)
(%) (1)
(t) (1)
(%)
HPI System 100 95-100 90-95 75 EFW System 100 95-100 90-95 85 DHR System 100 95-100 90-95 55 CFT System 100 95-100 90- 95 20 RCS Pressure Control System 90 95-100 90-95 60 Makeup / Letdown System 100 95-100 90-95 70 l
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SG Pressure Control System 100 95-100 90-95 60 Steam Generator 100 95-100 90- 9 5 50 Pressurizer 100 95-100 90-95 40 Quench Tank 100 95-100 90-95 50 Control Room Layout 100 90 80 70(3)
RCS Piping 100 95-100 90-95 50 NOTES:
( l') Units 1 & 2 show same percents due to parallel design and procurement for both units.
j (2 ) All of these values are based upon the present design and does not include
" lessons learned" changes resulting fran TMI-2.
(3 ) This is for panel installation only.
It does not include field cable tenninatiers,
HVAC and lighting. With all these included, a value of about 30-35% applies.
MIDLANO UNIT 2 System / Canpanent Design Component Component Construction Co mleted Procurement Fabrication Completed
(%)(1 & 2)
(%) (1)
(%) (1)
(%)
HP1 System 100 95-100 90-95 80 EFW System 100 95-100 90- 9 5 85 s
DHR System 100 95-100 90-95 70 CFT System 100 95-100 90- 9 5 50 RCS Pressure Control System 90 95-100 90-95 60 Makeup / Letdown System 100 95-100 90-95 75 SG Pressure Control System 100 95-100 90-95 60 Steam Generator 100 95-100 90- 95 65 Pressurizer 100 95-100 90-95 50 Quench Tank 100 95-100 90 -9 5 75 Control Room Layout 100 90 80 70(3)
RCS Piping 100 95-100 90-95 85 NOTES:
(1)
Unit 1 and 2 show same percents due to parallel design and procurement for both units.
(2 )
All these are based upon the present design ar.d does not include " lessons learned" changes resulting frcrn TMI-2.
(3 )
This is for panel installation only.
It does not include field cable tenninals, HVAC and lighting. With all thesa then included, a value of about 30-35% applies.
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p NORTH ANNA UNITS 3 AND 4 Sys5em/ Component
. Design Component Component Constructier Compl eted Procurement Fabrication Completed
(%)
(%)
(%)
(%)
HPI System 60 90 90 10 EFW System 60 90 90 10 DHR System 60 90 90 10 CFT System 60 90 90 10 RCS Pressure Control System 60 90 90 10 Makeup / Letdown System 60 90 90 10 SG Pressure Control System 60 90 90 10 Steam Generator 60 90 90 10 Pressurizer 60 90 90 10 Quench Tank 60 90 90 10 Control Room Layout 60 90 90 10 RCS Piping 60 90 90 10
BELLEFONTE 1 System / Component Design Component Component Construction l Completed P rocurement Fabrication Completed
(%)
(%)
(%)
(%)
HPI System 85 90 80 45 EFW System 98 90 85
~65 OHR System 95 90 80 45 CFT System 98 80 70 30 RCS Pressure Control System 99 100 100 50 Makeup / Letdown System 85 90 80 45 SG Pressure Control System 99 100 100 50 Steam Generator 100 100 100 95 Pressurizer 100 100 100 50 Qu'ench Tank 100 100 100 100 Control Room Layout 99 100 100 60 RCS Piping 100 100 100 90 e
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BELLEFONTE 2 System / Component Design Component Component Construction Completed P rocurement Fabrication Completed
(%)
(%)
(%)
(%)
HPI System 85 90 60 5
EFW System 98 90 60 0
OHR System 95 90 70 5
CFT System 98 80 45 5
RCS Pressure Control System 90 100 100 10 Makeup /Letdcwn System 85 90 60 5
SG Pressure Control System 90 100 100 10 Steam Generator 100 100 100 80 Pressurizer 100 100 1 00 50 Quench Tank 100 100 100 100 Control Room Layout 95 100 100 40 RCS Piping 100 100 100 45
l WPPSS 1 1 4 Systeh/ Component Design Component Component Constructi-Compl eted Procurement Fabrication Completec
(%)
(%) (2)
(%) (4)
(%)
HPI System 100 100 95 10 EFW System 100 100 95 5
DHR System 100 100 95 5
CFT System 100 100 95 0
RCS. Pressure Control System 100 100 100 0
Makeup / Letdown System 100 100 95 10 SG Pressure
' Control System (1) 100 100 95 0
Steam Generator 100 100 100 0
Pressurizer 100 100 100 0
Quench Tank 100 100 100
'100 Control Room Layout (3) 100 100 0
0 RCS Piping 100 100 100 0
NOTES:
(1)
Only level control system.
(2)
All equipment on order but may not have been delivered.
(3 )
Panel Layout complete and instrumentation for panel.
(4)
Major component fabricated, but some special order item not yet delivered.
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ENCLOSURE C
[f* "24,k UNITED STATES (g
NUCLEAR REGULATORY COMMISSION
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' 00T 2 51979 Docket No.:
50-438 and 50-439 Mr. H. G. Parris Manager of Power Tennessee Valley Authority 500 Chestnut Street, Tcwer II Chatanooga, Tennessee 37401
Dear Mr. Paris:
SUBJECT:
10 CFR 50.54 REQUEST REGARDING THE DESIGN ADEQUACY OF BABCOCK AND WILCOX NUCLEAR STEAM SUPPLY SYSTEMS UTIL:Z:NG ONCE THP.00GH STEAM GENERATORS Several hardware and procedural changes have been made to operating PSh plants to reduce the likelihood of recurrence of a TMi *,ype accident.
These changes have been in the area of auxiliary feedwater systems, integrated control s'ystem, reactor protection system, small-break loss-of-coolant accident analysis and operator training and procedures.
However, at this time, we are beginning to look more deeply into additional design features of BSW plants to contider if any further system modifications are necessary.
The use of once-through-steam-generators (OTSG) in B&W plants has an opera-tional advantage in that it provides a small degree of steam superheat, as, contrasted with the conventional saturated U-tube stean generator.
In addition, it provides for less water inventory thus naking a steam line break less severe. However, the relatively low water inventory with the presence of a liquid-vapor heat transfer interface in the active heat transfer zone closely couples the primary system to the stean generator conditions with a consequently high sensitivity to feedwater-flow rate Enclosure I to this le'ter addresses system problems ano perturbations.
t staff concerns in this area. At present, we are investigating whether B&W plants are overlysensitive to feedwater transients, due to the OTSG concept, as coupled with the pressurizer sizing, ICS design, and PORV/ reactor trip set points.
made of undae-AspartofthepostTMI-2 effort,detailedanalyseshavebeegH 4*
cooling transients for B&W plan the OTSG design, B&W plants have al severe overcooling e/ents.
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