An Evaluation of Dismantling Scenarios Using a Computer Simulation Technology for KRR-1&2

Transcription

1 An Evaluaton of Dsmantlng Scenaros Usng a Computer Smulaton Technology for KRR-1&2 S.K. Km, H.S. Park, K.W. Lee, W.Z. Oh, J.H. Park Korea Atomc Energy Research Insttute 150, Dukjn-Dong, Yuseong-Gu, Daejeon Republc of Korea ABSTRACT A graphc smulaton has been used to desgn and verfy new equpment and has also been expanded to vrtual prototypng technology [1~5]. In the nuclear decommssonng feld, ths technology has been utlzed to valdate the desgn of dsmantlng processes and to check the nterferences and collsons n dsmantlng scenaros. However, a graphc smulaton only provdes us wth vsble result t just provdes us wth llustratve nformaton of the decommssonng process. A scenaro evaluaton program has been developed usng the computer smulaton technology to create an effcent decommssonng plan. In the D&D plannng stage, t s mportant that the scenaros are evaluated from a engneerng pont of vew because the decommssonng work has to be executed economcally and safely followng the best scenaros. Therefore, we need several modules to evaluate scenaros. We composed the systems lke ths: 1. Decommssonng DB module for managng the decommssonng actvty nformaton (nuclear faclty data, worker s data, radoactve nventory date, etc.). 2. Dsmantlng process evaluaton module 3. Vsualzaton module for a radoactve nventory and a dsmantlng process usng 3D CAD and vrtual realty technology. 4. Analyss module for the evaluaton results of a dsmantlng process. The evaluaton module s capabltes produce a dsmantlng schedule, quantfy radoactve waste, vsualze a radoactve nventory, estmate a decommssonng cost, estmate a worker s exposure, and check for nterference/collsons. After usng the smulaton results, the expert rankng system to evaluate scenaros for economcs and worker s safety are mplemented. The expert rankng system s a powerful and flexble decson makng process to help set prortes and make the best decsons when both the qualtatve and quanttatve aspects of a decson need to be consdered. By reducng complex decsons to a seres of one-on-one comparsons, then syntheszng the results, the experts rankng system not only helps decson makers arrve at the best decson, but also provdes a clear ratonale that t s the best. In the future ths scenaro evaluaton system wll be verfed by beng appled to the ongong KRR-2 decommssonng project. We beleve that t wll also be useful to create a decommssonng plan for other nuclear faclty decommssonng projects.

2 INTRODUCTION In Korea, KRR-1&2 (Korea Research Reactor 1&2,TRIGA Mark II&III), had been operated snce 1962 and 1972 respectvely untl ther planned shut down[6,7]. However, because of the deteroraton of the utltes, and the change to the hgher populaton area by the accelerated urbanzaton of the surroundngs, a converson to a comfortable and safe envronment was requred. Also because of HANARO that s a multpurpose research reactor, whch started normal operaton at the new ste of KAERI, the outdated research reactors lost ther usefulness. For these reasons, the decommssonng of the KRR-1&2 was decded. The decommssonng work of KRR-2 wll be fnshed n 2005 and KRR-1 wll start to be dsmantled shortly afterward. We are also promotng the decommssonng R&D programs as well as the KRR-1&2 decommssonng project. We carred out the development of a graphc smulaton for the man dsmantlng process, the decommssonng data base system, remote dsmantlng equpment, and the automatc measurement system. Snce many of the world s nuclear reactors are agng, ther safe decommssonng has emerged as an mmnent task. Henceforth, the world s nuclear ndustres have ntated decommssonng and decontamnaton (D&D) projects and relevant R&D programs snce the md 80 s. Currently, many D&D technologes are commercally avalable. However, decommssonng a nuclear faclty s stll a costly and possbly hazardous project. To secure a worker s safety, many have used physcal mock-ups before dsmantlement. However, t was very expensve to make them and t was mpossble to reuse them. Therefore usng conventonal mockups causes an abrupt ncrease n the decommssonng cost. But, as the computer graphc technology has been enhanced, a dgtal mockup has started to compete wth conventonal mockup systems. Currently t s beng used n many commercal companes, such as the automoble, arplane, manufacturng ndustres, etc., to desgn and verfy ther products and for tranng and brefng of the staff. In the nuclear decommssonng feld, graphc smulaton technology has also been used snce a few years ago[8]. However, t has been lmted to check the problems of dsmantlng scenaros and tran workers. But we need to have a system that can evaluate scenaros quanttatvely, effectvely, and precsely before the real dsmantlng works. Therefore for ths reason, we have been developng a dgtal mockup system wth functons such as a dsmantlng schedule, decommssonng costs, wastes, worker s exposure dose, and a radaton dstrbuton. Ths system also adopted a 3D vrtual realty(vr) system and a data base(db) system. Ths paper presents the status of the development of the dsmantlng dgtal mockup system for KRR-1&2. DISMANTLING DIGITAL MOCKUP SYSTEM OVERVIEW The dsmantlng dgtal mockup system s composed of 4 dfferent parts: a database part, vsualzaton part, evaluaton part, and an analyss part. Fg. 1 shows the conceptual dagram of the dsmantlng dgtal mockup system. The decommssonng DB system stores the data concernng the dsmantlng schedule, actvty vsualzaton system, cost evaluaton system, 3D CAD, and so on. The vsualzaton part has three sub-parts; a dsmantlng smulaton, an actvty vsualzaton, and a vrtual realty secton. Dsmantlng smulaton shows us an overvew of the dsmantlng process. It s mportant to know whch parts are hghly radoactve. By usng a graphc mappng technque, actvty levels were vsualzed and contoured n a 3D modelng. Ths may contrbute to an ncrease of the radaton awareness for workers and to provde plannng nformaton as to whch tems are gong to be cut and treated as actvated waste. VR

3 technology has been used as a smulaton technque because t s possble to move around durng a playback, allowng the spectator to vew the scenaro from any angle [8,9]. In the evaluaton secton, there are: a dsmantlng schedule, waste estmaton, dsmantlng cost, and worker s exposure subparts. The dsmantlng schedule offers the expected man-hours for each dsmantlng acton and calculates dsmantlng costs of a scenaro. The exposure dose part s a smulaton system that can estmate a worker s exposure dose n a vrtual space. The analyss part has collson nterference and scenaro evaluaton subparts. The collson check can be used to fnd the best removal path [10,11]. The goal of ths system s to fnd the best scenaro that could be mplemented from the estmated results. Fg. 1. Conceptual dagram of dsmantlng dgtal mockup system 3D MODELING AND VIRTUAL REALITY The 3D modelng nformaton s really mportant to understand dsmantlng tems and dsmantlng processes. In order to construct the decommssonng DMU system, we bult 3D models whch are the man dsmantlng tems such as the beam port, thermal column, core, and sheld concrete, the envronments of KRR-1&2, and the dsmantlng tools. The vrtual envronments of KRR-1&2 were bult by usng the EON studo. The left sde pcture of Fg. 2 shows the vew of the vrtual realty of KRR-1. In ths poston we can navgate the KRR-1 n real-tme. A specfc area or opposte sde of an object can be seen n on any area and rotated on a real-tme bass. The Rght sde pcture of Fg. 2 shows the snap shots for the core dsmantlng process of KRR-1. Once we revew the snap shots we can understand the entre dsmantlng process. 3D RADIOACTIVITY VISUALIZATION A 3D radoactvty vsualzaton module s essental to classfy the radoactve wastes and to defne the cuttng areas before makng a dsmantlng scenaro. It s very useful for worker s tranng before dsmantlng work as the radoactve areas can be shown vsually. The method of a 3D radoactvty vsualzaton s lke Fg. 3. Frstly 3D model s prepared. Secondly, the 3D model s dvded nto lots of

4 nodes and then a radoactve data set s constructed. Thrdly the connect data s connected wth the nodes of the 3D model. Fnally we can vsualze the 3D radoactve level for actvated tems. Fg. 2. Vew of vrtual realty of KRR-1 and vsualzaton of core s dsmantlng smulaton for KRR-1 Fg. 3. Method of 3D radoactvty vsualzaton DISMANTLING SCENARIO EVAULATION MODULE Schedule Smulaton of the Scenaros A schedule smulaton of the scenaros s needed to calculate the scenaro duraton. The runnng tme of the schedule s closely related wth the calculaton of the dsmantlng cost. The man-power requred n any scenaro s used to calculate the cost of personnel expenses. Equaton 1 (Eq. 1) s derved to calculate the workng tme. Abbrevatons meanngs are; BT s the dsmantlng basc unt tme, whch equals the man-hours needed for each dsmantlng work. They were calculated by usng a machne s specfcatons; for nstance, the cuttng tme of a hydraulc shear machne for dfferent materals and usng

5 decommssonng experence data of KRR-2 for nstance, a machne s nstallaton tme, scaffoldng nstallaton tme etc.. s the number of dsmantlng actvtes. Sometmes dsmantlng work becomes R an teratve actvty. In ths case the man-hours are calculated by multplyng an amount of tme for actvtes by the teratng number. equals the weghtng factors. As shown n Table I, weghtng W j factors are dvded nto 5 dfferent categores such as the heght, respratory protecton, radaton/alara, protectve clothng, and work breaks. In order to change the man-hours nto days, the total man-hours are dvded by N and 8(8 means 8 hours per workng a day). T n m T =, T = BT R 1 + W = 1 N 8 = 1 (Eq. 1) where, T = Total dsmantlng schedule (Days) T = Calculated man-hour each dsmantlng work (Man-h) N = Number of needed person (Persons) BT = Dsmantlng basc unt tme (Man-h) R = Number of work (Frequences) W = Weghtng factors (%) Table I. Weghtng Factors for Calculatng the Dsmantlng Schedule Work dffculty factors Weghtng (%) Standards Heght 15 Work n the 2 m over/under Respratory Protecton 38 Whether usng resprator or not Radaton/ALARA 15 Whether workng n radoactve area or not Protectve clothng 23 Whether wearng protectng cloth or not Work break 9 Whether takng a break or not Calculaton of Waste The quantty of waste s vared dependng on each scenaro because the cuttng area should be changed when applyng dfferent dsmantlng methods. The amount of waste s also closely related to the decommssonng cost. As the amount of waste ncreases, the decommssonng cost also rses. It s sgnfcant to know the expected waste. A volume calculaton functon n a 3D CAD program s used to estmate the expected waste. Frst, the expected waste regons are classfed through the 3D radoactvty vsualzaton module. Then the volumes of the classfed areas are calculated by usng a volume calculaton functon n a 3D CAD program. Fnally, the amount of waste was reclassfed wth dfferent materals and dfferent radoactve levels. Table II shows the example of the beam ports of KRR1 for both

6 the damond wre saw method and the core borng method. The left sde pcture of Fg. 4 shows the graphcal user nterface (GUI) depctng the calculated waste volume. Table II. Waste Volume of KRR-1 s Beam Ports for the Damond Wre Saw Method and Core the Borng Methods Waste type Damond wre saw method Waste volume(cm 3 ) Core borng method Steel 4.12x x10 4 Alumnum 2.01x x10 4 Concrete 1.43x x10 5 Estmaton of Decommssonng Cost As shown n (Eq. 2), the decommssonng cost scenaro can be expressed by summng the personnel expenses, tool expenses, and waste treatment expenses. (Eq. 3) shows the equaton of personnel expenses. The personnel expenses can be calculated as man-hours whch are calculated n the schedule smulaton module whch multples average labor cost. (Eq. 4) shows the equaton of the tool expenses. The tool expenses can be calculated by multplyng the machne s unt cost wth number of machnes. (Eq. 5) shows the equaton of the waste treatment expenses. The waste treatment expenses can be calculated by multplyng the waste drum unt cost wth a number of drums. A number of drums can be found by dvdng the total volume of waste wth the volume of drum and porosty. C = PE + TE + WE (Eq. 2) where, PE, TC, and WC equal respectvely the personnel expenses, tool expenses, and waste treatment expenses. PE = n = 1 T AMC (Eq. 3) where, PE means the personnel expenses, T equals the man-hours for each dsmantlng acton, and AUC equals the average labor cost. TE = n = 1 M NOM (Eq. 4) where, TE means the tool expenses, M equals the machne unt cost, and NOM equals the number of machnes.

7 n V WE = D V =1 total waste waste drum P (Eq. 5) where, WE equals the waste treatment expenses, D equals the waste drum unt cost, V total waste equals the total radoactve waste for an object, V waste drum equals the waste drum whch contans radoactve waste, and P equals the porosty. Evaluaton of Workers Exposure The evaluaton of a worker s exposure for a dsmantlng actvty s mportant from the aspect of the worker s safety. In order to select the best scenaro, the evaluaton of a worker s exposure should be performed wth the radoactve objects. MCMP program was used to calculate the exposure regardng workers who work n the actvated area. The rght pcture of Fg. 4 shows the GUI(Graphc User Interface) of the evaluaton module of a worker s exposure. There are accumulated dose graphs for workers, dose charts at each poston for worker, and ther data table set n the GUI. Data table set Accumulated dose Waste volume n dfferent materals Waste volume n dose levels Doses at each poston Fg. 4. Graphc user nterface of waste and worker s dose Evaluaton of Scenaros The evaluaton of scenaros s based on selectng ndependent crtera and on expert s rankng of the alternatves wthn a specfed rankng system. To make the evaluaton of scenaros more realstc, the crtera were chosen and the alternatves ranked accordng to the feasblty of varous techncal decsons. The crtera were chosen and analyzed to classfy the crtera by functonal groups. The weghtng factors were assgned by the experts for the crtera and ther groups. The weghtng factors ndcate the sgnfcance of the crtera for the mplementaton of varous decommssonng alternatves. The decommssonng alternatves were analyzed usng the crtera whch were chosen by determnng quanttatve and qualtatve features of a practcal mplementaton of the alternatves. Dependng on whether the mplementaton features are quanttatve or qualtatve, the crtera were assgned to quanttatve or qualtatve categores. The decommssonng alternatves were analyzed and compared, wth the followng rankng system for each crteron:

8 5 very good 4 good 3 not good 2 bad 1 very bad Groups of experts were ntervewed ndependently and the results were averaged to rank each decommssonng alternatve by the chosen crtera. The crtera were classfed nto the followng categores chosen accordng to the current requrements for decommssonng actvtes: Category 1 economc effcency crtera Category 2 safety crtera A weghtng factor was defned for each category, χ (where: =category). The weghtng factors were defned by averagng the rankngs of the ndependent experts. The weghts were then normalzed,.e., χ = 1. The followng weghted sums were calculated for each decommssonng alternatve: S χ (Eq. 6) = b j j where = category; j= crtera; b= rankng of crtera j n category ; and χ = weghtng factor for category. Table III. Analyss of the Alternatves by the Economc Effcency Crtera Crtera Scenaro 1 b j Scenaro 2 b j 1. Costs of dsmantlng actvtes Costs of specal equpment and expendables Costs of radoactve waste handlng Costs of personnel tranng Rate of recyclng materals return 1 1 Total 13 11

9 Table IV. Analyss of the Alternatves by the Safety Crtera Crtera Scenaro 1 b j Scenaro 2 b j 1. Personnel safety (mnmzaton of personal dose rate) Safety of the envronment Contnuty of personnel work Necessty to use unque equpment Rate of recyclng materals return 3 3 Total Table V. Weghtng Factors by Categores Crtera χ 1. Economc effcency Safety Table VI. Results of the Scenaro Evaluaton Crtera Scenaros Scenaro 1 Scenaro 2 Economc effcency Safety Total Table III and IV show the evaluaton results of the economcal effcency category and the safety category regardng two scenaros of the thermal column n KRR-1. Table V shows the weghtng factors that were derved from Tables III and IV. Fnally Table VI shows the scenaro evaluaton results by consderng the economc and safety aspects.

10 CONCLUSION A dgtal mock-up system whch can evaluate the scenaros for KRR-1&2 was developed along wth the dsmantlng schedule smulaton module, waste calculaton module, decommssonng cost module, worker s exposure module and vrtual realty module. On the bass of the evaluaton results, the scenaros can be quanttatvely compared and evaluated. Ths system wll be appled to KRR-1 to obtan the best scenaro and we expect t to be used as a future systems engneerng tool n other nuclear power plant decommssonng. Ths system wll be upgraded to obtan data from the decommssonng DB system. Ths can lead to a decrease of the decommssonng cost and the mprovement of a worker s safety. REFERENCES 1. Fsher, J. J. (1985). Applyng Robots n Nuclear Applcatons. RI/SME Robots Conference. 2. Gregory, A. R. (1984). The Use of Remote Handlng Equpment for Gas Cooled Reactor Inspecton. Proceedng of Remote Handlng n Nuclear Facltes: Clement, G. (1984). Remote Handlng and Transfer Technques n Dsmantlng Strategy. Proceedng of Remote Handlng n Nuclear Facltes: Baker, A. (1984). Remote Handlng Equpment for the Decommssonng of the Wndscale Advanced Gas Cooled Reactor. Proceedng of Remote Handlng n Nuclear Facltes: Costa, L. (1989). Remote Operaton n Decommssonng. Decommssonng of Nuclear Power Plates 6. Jung, K. J. (1997). Decommssonng of TRIGA Mark 1&2. KAERI/RR-1798/97 7. Park, J. H. (2003). Decontamnaton and Decommssonng Project for the Nuclear Facltes. KAERI/RR-2304/ Baker, C. P. (1994). Parametrc Desgn Usng IGRIP. Proceedng of the DENEB User Group Conference: Clfford, H. D., Ekdahl, S. and Tulenko, J. S. (1994). Vrtual Realty for Moble Robot Control. Proceedng of the DENEB User Group Conference. : Salmnen, M., Tuokko, R. and Sulkanen, J. (1995). Development, Experments and Experence n Telerobotcs and VR Usng the TELEGRIP Software. Proceedng of the DENEB User Group Conference: Barnaby, J. B. (1999). The Use of Real-Tme Computer Graphcs to Assst Remote Reactor Inspecton. Proceedng of the DENEB User Group Conference: