ML20154M324
| ML20154M324 | |
| Person / Time | |
|---|---|
| Issue date: | 03/06/1986 |
| From: | Stello V NRC OFFICE OF THE EXECUTIVE DIRECTOR FOR OPERATIONS (EDO) |
| To: | Palladino Office of Nuclear Reactor Regulation |
| References | |
| REF-GTECI-A-45, REF-GTECI-DC, TASK-A-45, TASK-OR NUDOCS 8603140048 | |
| Download: ML20154M324 (4) | |
Text
_ _ _ _
MAR 0 61986 MEMORANDUlf FOR: Chairman Palladino FROM:
Victor Stello, Jr.
Acting Executive Director for Operations
SUBJECT:
MEETING WITH THE BELGIAN REPRESENTATIVES REGARDING THE DESIGN PHILOSOPHY OF DOEL 3 AND 4 Representatives from the Belgian Safety Review and Inspection Organization, Vincotte, and the Belgian Architect Engineer.Nr Doel Units 3 and 4, recently briefed the NRR staff on the safety teatures and experience of these plants. The NRC regulations provided the fcundation for the design requirements imposed en these Belgian units. However, additional design criteria were imposed due to local ecoditions and policy.
Knowledge of the design and construction of these facilities provides valuable insights for application in our related activities, such as the resolution of USI A-4S, Backfitting, and Safety Goal Policy Development.
Therefore, I am forwarding NRR's meeting sumary f ur your information.
Original signed by Victor Stello Victor Stello, Jr.
Acting Executive Director for Operations
Enclosure:
Meeting Sumary DISTRIBUT_ ION Central File cc: Comissioner Roberts NRC PDR Comissioner Asselstine EDO Reading Ccmissioner Bernthal TAMB Reading Comissioner Zech PPAS SECY VStello OPE HDenton 0GC JFunches TSpeis p
Contact:
T. Speis NRR MW1111ams 49-27517
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1 Enclosure MEETING WITH BELGIAN REPRESENTATIVES REGARDING THE DESIGN PHILOSOPHY OF DOEL 3 & 4
SUMMARY
l On February 11, 1986, NRR met with representatives from Vincotte, the Belgian Safety Review and Inspection Organization, and Tractionel, the Architect Engineer, to discuss the design and operating experience of the Doel 3 & 4.
This report, which provides a summary of that meeting, is provioed to you for your information.
The latest Doel units (Nos. 3 and 4) are of particular interest to the staff since they are " bunkered" designs that provide a fairly full featured "second level" of protection against most external events. The Belgians are backfitting the earlier Doel 1 & 2 units to provide additional protection.
Knowledge of the design, construction and operation of these facilities provides valuable insights for application in our related activities such as the resolution of USI A-45, Shutdown Decay Heat Removal, Safety Goal Policy development, and backfitting.
Belgium is densely populated and highly industrialized.
The Doel site is Tocated approximately 9 miles northwest of Antwerp, Belgium.
In light of the population in the vicinity and due to the proximity of major petrochemical facilities, a shipping channel, and the history of military aircraft crash incidents throughout Europe, the design basis of the plants included protection against specific external events including gas cloud explosion, large-scale fire, direct hit aircraft crashes, acts of malviolence, and other accidents making the control room inaccessible. Doel 3 is primarily of Framatone (900 j
MWe) design while Doel 4 is primarily of Westinghouse (1000 MWe) design. The features incorporated into the design to accommodate these events include a crash / explosive resistant secondary containment and a bunker that houses three independent physically separated 50% trains of emergency feedwater (EFW), reactor coolant make-up and boration, and two 100% trains of reactor coolant pump seal injection. Each of the three redundant trains are independent and self sufficient from water supply to injection. The bunker protects all of the support systems, including electrical power and cooling systems for these functions and provides protection for portions of other essential systems such as the main steam system. With a complete loss of the control room, the bunker systems are designed to automatically bring the plant to hot shutdown and maintain that condition for up to three hours following activation without any operator action.
It should also be noted that without the bunker, Doel 3 & 4 have a higher degree of redundancy and separation than their U.S. counterparts. First level systems include three 100% trains of AFWS, RHR, and HPSI.
a 4^ The decision has also been made to backfit Doel 1 & 2 with an additional single train of equipment, including EFW and other functions, that would be manually controlled and not meet single failure criteria.
Some of the key points to note are the following:
o The Doel 3 & 4 design evolved solely from a government mandated licensing basis that included protection against certain external events. The method to meet the design basis, was left primarily to the utility and the Architect Engineer.
o The Belgians did use a " Safety Objective" for plant design. However the safety analysis is based on deterministic principles. The general safety objective was that the risk to the public from all reactor accidents would be much less than other risks of life. Since construction began in 1975, other more detailed criteria were based on WASH-1270.
They view the usefulness of PRA as we do - as a tool to provide insights into the plant safety.
o The decision to add the bunker rather than redesign or re-site the plant appears to have resulted from the limitations of the time, e.g., site availability, schedule for installation / construction etc. The bunkered symm of these units was designed primarily to protect against certain evencs and not to improve the overall mitigation of accidents.
- However, during the last few years, the margin afforded by this extra safety equirment has facilitated their resolution of several safety issues such as Station Blackout, i.e., an extra dedicated diesel for each of the three trains is bunkered for each unit.
o Decisions, early on, concerning the plant design basis resulted in cost effective construction (the bunker was estimated to cost about 8% of the total plant cost), resolved initial licensing concerns, and were again highly cost effective when utilized to resolve new safety concerns that emerged throughout the years of construction and operation, o
The Doel bunkers are not intended to provide additional protection against internal events such as steam generator tube ruptures or loss of coolant accidents. This bunker concept relies on the retention of primary coolant system serviceability, o
The Doel 3 & 4 plant availability has not been degraded by adding the additional bunker equipment.
The reliability of the bunkered systems is good and there have been no significant spurious actuation problems.
s o The government authorization to operate all Belgian plants includes a requirement for a 10-year periodic reevaluation of the plant to the most recent rules and practices in the U.S. and the European community. This reevaluation provided the engineering basis for backfit of Doel 1 & 2.
Important improvements, such as TMI improvements were implenented immediately and were not delayed to the 10 year interval, however the 10 year review provides for a coordinated and more comprehensive evaluation.
o The backfit of Doel 1 & 2 was based on engineering judgement to remedy problems that were identified from (a) a comparison of the facilities with the currect Itcensing(requirements, and (b) operating experience reviews of Doel 1 & 2 and c) significant events noted in the plants of other countries (including TMI). The addition of dedicated systems seems to be the preferred approach to improve older European plants to remedy problems on separation, physical protection, and shared support systems.
o The potential exists for another Belgian unit to be ordered, in the late 1980s, and constructed at the Doel site. Our impression from the meeting is that the design of such a new unit would not be identical to Doel 3 & 4.
Therefore, the latest existing bunkered design is not contemplated as a standard design in Belgium.
The staff has been following the various design alternatives of other countries to accommodate different protection objectives. Lessons have been learned from our brief review of Sizewell and current review of Paluel. Regarding the general utilization of bunkered systems, it appears that these designs accommodate local criteria but are not developed to the point where a standard international design is emerging. This view is useful regarding our thoughts for standard plants. The economic and social feasibility of the nuclear-plant produced the non-standard design of Doel 3 & 4, and it is obvious that the plant site can impact final plant design.
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