ML20012B576

Informs Commission of Working Group Activities Under US-USSR Joint Coordinating Committee for Civilian Nuclear Reactor Safety

ML20012B576
Person / Time
Issue date:	03/07/1990
From:	Taylor J NRC OFFICE OF THE EXECUTIVE DIRECTOR FOR OPERATIONS (EDO)
To:
References
TASK-PII, TASK-SE JCCCNRS-WG-1, JCCCNRS-WG-10, JCCCNRS-WG-12, JCCCNRS-WG-2, JCCCNRS-WG-3, JCCCNRS-WG-4, JCCCNRS-WG-5, JCCCNRS-WG-6, JCCCNRS-WG-7, JCCCNRS-WG-8, JCCCNRS-WG-9, SECY-90-077, SECY-90-77, NUDOCS 9003150347
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RELL ASED 10 THE PDR l [' [gs 5/A7/fo i 6 ate in; as POUCY ISSUE SECY-90-077 March 7, 1990 (Inf0Ntion) f_qt: The Commissioners l f.r.o.a): James M. Taylor Executive Director for Operations Sub.iect : REPORT COVERING DISCUSSIONS OF JCCCNRS WORKING GROUPS 2, 5, AND 9 IN THE USSR, DECEMBER l-12, 1989 Puroose: To inform the Commission of working group activities under the U.S.-USSR Joint Coordinating Committee for Civilian Nuclear Reactor Safety (JCCCNRS). Di scussipf1: Attached for your information is the report of visit of the NRC delegation that travelled to the USSR in December 1989. These discussions involved Working Groups 2 (Analysis of the Safety of Nuclear Power Plants in the USSR and the U.S.), S (Modernization /Backfitting), and 9 (Diagnostics, Analysis Equipment, and Systems for Supporting Operators). The results of these meetings are contained in the enclosed Memorandum of Meeting and individual trip reports. s J es a A xecutive Director for Operations

Attachment:

2/26/90 Memorandum CJHeltemes to JMTaylor and HRDenton, " Report of Visit to the USSR, December 1-12, 1989," w/ enclosures

Contact:

NOTE: TO BE MADE PUBLICLY Gordon Fow..sr, GPA/IP AVAILABLE IN 10 WORKING 49-20329 DAYS FROM THE DATE OF THIS PAPER DISTRIBUTION: Commissioners EDO OGC ACRS OIG ACNN GPA ASLLP ' p'/, REGIONAL OFFICES ASLAP SECY 90D3/5 OS+7 R

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February 26, 1990 i e MEMORANDUM FOR: James M. Taylor, Chairman, JCCCNRS Harold R. Denton, Director, GPA FROM: C. J. Heltemes, Jr., Deputy Director Office for Analysis and Evaluation of Operational Data

SUBJECT:

REPORT OF VISIT TO THE USSR, DECEMBER 1-12, 1989 I.

Background

An NRC delegation travelled to the USSR on December 1, 1989, for a week of working group meetings under the auspices of the Joint Coordinating Committee on Nuclear Reactor Safety (JCCCNRS). These meetings were part of a series of 1 meetings approved in protocols between the U.S. and the USSR in August 1988 and in October 1989. The following working groups (WGs) met at the December meeting: WG 2 - Analysis of the Safety of Nuclear Power Plants in the USSR and the U.S. (led by Ashok Thadani. NRR) WG S - Modernization /Backfitting (led by Jack Heltemes, AEOD) WG 9 - Diagnostics, Analysis Equipment and Systems Supporting Operators (led by Ken Raglin, AEOD) The Head of the U.S. Delegation was Jack Heltemes. II. Summary I The meetings of the three working groups were held inside the security gates of the Kurchatov Institute. The substantive discussions began on December 4 and ended on December 7. After the opening remarks, N. N. Ponomarev-Stepnoy, First Deputy Director of the Kurchatov Institute and Co-Chairman of the JCCCNRS, was called to other business, and Gleb Lunin (Deputy Director of the Institute for Nuclear Reactors and Co-Leader of Working Group 2) replaced him as head of the Soviet side. After Dr. Lunin outlined the plan of the week, the groups ' departed to separate meeting rooms, where they met for the next four days. Over the weekend, the delegation visited the Rovno nuclear power plant in the Ukraine. The results of the meetings are described in the " Memorandum of the Meeting of the Working Groups of tha U.S.-USSR JCCCNRS, December 4-11, 1989" (Enclosure 1). For each working group, the Memorandum summarizes the subjects discussed I

s' o l t I and the conclusions and recommendations reached in the discussions. Addition-ally, each of the Working Group leaders end the International Programs representative have prepared trip reports of the meetings and the visit { (Enclosures 2-5). ks Y.. M Deputy Director b C.

iTCeNel, Of for Analysis and Evaluation o

perational Data

Enclosures:

As stated cc w/ enclosures: J. Sniezek, NRR T. Speis, RES { p E. Jordan, AEOD S. Rosen, DOE M. Schulman, DOE T. Murley, NRR E. Beckjord, RES R. Brady, SEC/ADM J. Shea, IP/GPA R. Hauber, IP/GPA J. Clifford, EDO

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c e. o ( l ? f r E' i e l f M-4 i MEMORANDUM OF THE MEETING OF THE WORKING GROUPS OF THE US-USSR JOINT COORDINATING COMMITTEE ON CIVILIAN NUCLEAR REACTOR SAFETY December 4-11, 1989 The fourth meeting of the working groups of the US-USSR i Joint Coordinating Committee on Civilian Nuclear Reactor Safety (JCCCNRS) was held in Moscow at the Kurchatov Institute on~ December'4through 11, 1989. Three of the ten wdfling groups had discussions. The working groups were as follows: L WORKING GROUP Os ANALYSIS OF THE SAFETY OF NUCLEAR POWER PLANTS IN THE USSR AND THE US WORKING GROUP 5: MODERNIZATION /BACKFITTING WORKING GROUP 9: DIAGNOSTICS, ANALYSIS EQUIPMENT AND SYSTEMS FOR SUPPORTING OPERATORS The US side of the working groups was headed by Clemens J. (Jack) Heltemes, Jr.. Deputy Director, Office for Analysis and Evaluation of Operational Data. The USSR side was headed by Nikolay N.Ponomarev-Stepnev. First Deputy Directer. I.V. Kurchatov Atomic Energy Institute. The -ecorts of the three working groups are provided in Appendin 1. A list of the participants in the working group sessions as well as observers is provided in Appendiu II. The lists of documents exchanged for each session are provided in Appendin III. This Memorandum of Meeting reports the major topics of discussion, conclusions, recommendations and proposed future actions. 1. Conclusions of Each Woriino Groun WORUING GROUP 2: ANAL.YSIS OF THE CAFETY OF NUCLEAR POWER Pl. ANTS IN THE USSR AND THE LJS AGREEMENTS AND CONCLUSTONS

1) Doth sides agreed that common modo failures should be given careful consideration in the design and man-mochine interface is important during off normal events.

1, 2) The participants agreed to discuss preliminary LOCA and ATWG analysis results at the next meeting. 1

, g,- ...i. i. :. i l 'The Soviets will provide a detailed presentation at the 0) next meeting with a number of examples on the role of the design features which inhibit operator intervention in off-normal conditions when selected parameters are within a prospecified range. The participants also agreed to conduct preliminary discussion of the importance of various types of communication during off normal events. 4) The Soviets will present the analysis of, as well as procedur al considerations for, steam generator tube rupture events at the next meeting. 3 5) The partic'ipants agreed to discuss the ROVNO and the South Texas response to station blackout events at the next meeting. Also, the Soviets will discuss probabilistic analysis of station blackout for ROVNO. 6) The two sides identified written questions from previotts meetings for which responses will be discussed at the next meeting. 1 RECOMMENDATIONS FOR FUTURE ACTIVITIES The f ollowing subjects are proposed to be discussed at the next meetings (a) Operator's guidance for coping with accidents taking into consideration specific design features. Penefits and disadvantages of allowed actions of the operator during an accident. Soviet information about the operator's guidelines related to the initiation of primary to secondary leakage. The philosophy of communication at all levels of persennel actions. (b) The study of the plant black-out. Questions related to probabilistic approach to safety assurance in such conditions. as well as the questions related to reactor coolant pump seals, and elimination of leakage from the primary circuit. I, r: ) Finali:ation of inout data to analy:e LOCA and ATWS. Consideration of the preliminary results of the analyses and finali:stion of input data. (d) Responses to the questions on FSAR related to South Texas and ROVNO plants. I

~ e o t t i i The time needed to cover the proposed work scope for the next meeting is estimated at seven working days. In addition, it was agreed that as part of that meeting, tours of a US nuclear power station and the NRC Emergency Response Center are desirable. For the fall meeting, it is recommended that the use of passive decay heat removal system and guidance with regard to the use of normal station equipment for beyond design basis accident control be discussed by USSR. Also recommended for the fall meeting is the initiation of more detailed discussion on containment design, capability, and philosophy. WORKING GROUP 5: MODERNf7ATION/BACKFITTING AGREEMENTS AND CONCLUSIONS 1. Doth sides agreed that this meeting was important and useful in obtaining a mutual understanding of the general approaches used in evaluating additional safety improvements for existing nuclear power plants. These approaches were frequently discussed in terms of actual examples. O. Both the US and USSR have ongoing programs to moderni:e and to maintain safety margins An light of new information. 3. It was observed that the backfit programs of the USSR tend to concentrate on each specific reactor while the program of the US tonds to backfit on a generic basis. 4. The US and USSR noted that economic considerations are often important factors in making backfit determinations. The quantitative determination of these costs and the relationship to the gains in safety are f requently subject to major uncertainties. For some proposed changes. quantitative analyses of risk reduction are not feasible. Thus, of ten backfit determinations must be made on the basis of engineering judgment. l 5. PRA studies provide unique and valuable indications of safety levels and weakness in design that may pose safety concerns. Both the US and USSR are using this analysis method to provide engineering insights that assist in identifying areas that may warrant backfitting.

However, neither country currently requires a full PRA for each plant.

6. A key aspect of backfit pregrams is knowledge of the level of safety established by the current licensing basis of each plant,,and the actual level of safety that exists day to; day in each plant. Proper and consistent backfitting .l...<. i C.T5 E! M b:2 N 5.'.dd.I.2 N 3 3.b v

F l e decisions depend on a centinuing assessment of this situation. As a result, activities to monitor the existing safety level relative to that required are essential. Particularly important in this regard are operational experienca reviews, inspection activities, and research i programs which include FRA studies. RECOMMENDATIONS FOR FUTURE ACTIVITIES WG-5 believes the next meeting agreed to in the Second Protocol would be of mutual benefit, in order to review and discussi a) a recent generic backfit including the associated analyses and justification, and the process used in terms of the identification of the safety problem, and the assessment, approval, and implementation of the backfits b) a recent plant-specific backfit, including the associated analyses and justification, and the process used in terms of the identification of the safety problem, and the assessment, approval and implementation of the backfiti and c) other aspects of a backfit program which are of high mutual interest. WORL'ING GROUP C t DIAGNOSTICS. ANAlv91S EOUIPMENT AND l 9Y9TE*5 FOR SUPPORTTNG OFFPATOR9 AGREEMENTS AND CONCLUSIONS 1. The first meeting of the working group proved fruitful and contributed to better understanding of the approaches in each country in the areas of diagnostics, use of simulators, personnel training, and use of emergency operating procedures. j 2. The working group believes that further discussion of the above matters would be very useful and would contribute to a better understanding of the practices in each country. 3. Full scope simulators are used for personnel training in both countries, but the use is much more widespread in the US. In the USSR, for personnel training purposes, a wide range of technical means are used including conceptual simulators and functional-analytical simulators. I

a.. L.. +. O dl f I-( i 1 i [ l 4. The use of engineering simulators or plant t analy:ers is increasing in both countries in order to analy:e potential emergencies and there which have occurred. 5. The concept of plant diagnostics in the USSR is to use systems and means for early detection of equipment failures and trancient prevention, while in the US more emphasis is placed on transient control and mitigation I efforts. t 6. At Soviet plants there is no safety parameter display system (SPDS), although a number of diagnostic systems provide functions similar to those performed by the safety parameter display systems. 7. Emergency operating procedures in the US are r symptom-based, while in the USSR they are event-based. 8. It appears that general approaches to the training of operators are somewhat similar, although additional information is necessary for a better comparison. THE MAJOR RECOMMENDATIONS OF THE WORKING GROUP ARE: 1. Share experience in the areas of diagnostics and persennel training through contacts between US and USSR nuclear industry specialists and by the potential exchange of computer codes, algorithms, and methodologies, subject t o-the necessary aoprovals. O. Consider the possibility of a separate visit during the next meeting in the US to the NRC Technical Training Center (in Chattanooga. Tennessee) for observation of safety parameter display systems and symptom-based emergency operating procedures. 1 3. Consider including in the Working Group 9 program a discussion of each country's efforts in the evolving area of severe accident training and simulation. 4 Develop the program for future activities of Working Group 9 for 1991 and beyond at the next meeting. PROPOEED FUTURE ACTIVITIES OF THE WORKING GROUP ARE: The proposed agenda for the next meeting agreed to in the second protocol is as follows: 1. Discuss operator support systems, including in-core and essential component diagnostics. Each country would 'I,<

l-l l 1.* ) l l provide additional detail of operatcr support systems t discussed at the initial meeting. 2. Discuss expert systems from the point of view of providing support for plant operators. 3. Discuss staffing and training of nuclear plant personnel, including training programs and emergency operating procedure training scenarios. 4. Discuss modular simulation of nuclear plant systems. December 11. 1989 FOR THE USSR STATE COMMITTEE FOR THE US NUCLEAR' FOR THE UTILIZATION OF REGULATORY COMMISSION ATOMIC ENEDSW57 5 N. N. onomarov-Stepnoy Clegh J. Hel M an. Jr. t /. tst s yv i l'

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6 e MEMORANDUM OF MEETING FOR WORL'ING GROUP Or ANALYSIS OF THE SAFETY OF NUCLEAR POWER PLANTS IN THE USSR AND THE US

1. WORKING GROUP SCOPE AND CONTENT OF DISCUSSIONS The main topics discussed by the USSR and the US participants were 1)

The Soviet philosophy for loss of enc' ant accident analysis and the input data needs for the rovne and South Texas plants for such analyses. O) The US philosophy of ATWS requirements including the history of the develpment of the ATWS rule and the input data needs for the Rovno and South Texas plants for the ATWS analysis. 3) Each country's philosophy for operator actions during off normal conditions. 4) Each country's approach to consideration of station blackout. 5) Each country's shutdown margin requirements during i cold shutdown and het shutdown conditions. I USSR presented its LOCA analysis philosophy and proposed an exchange of data in the format specified in computer manual documents. The USSR would provide data and input assumptions for Rovne for RELAP5 MOD 2 analyses. The US would provide the same for the South Texas plant for Soviet analyses using the TETCH-M code. Actual data anchange was proposed to be accomplished by correscondence. Feeliminary analysis results would be discussed at the next meeting and the inputs corrected as needed then. This proposal was taken under consideration by US noting the difficulty of getting all the required data for South Texas .j as well as a proposal to issue a joint report. Both parties agreed on the need to understand..: _ a : s used in the others computer codes in order te pre...a the nreper input data. Both parties agreed. hat ..e proposed LOCA to be )

.r.a l y :od for Rove.. inculd be a cold leg break located 650 mm

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The available ECCS should be 0 accumulators. O high pressure injection pumps and low pressure injection two accumulators should discharge into the lower pumps. plenum and i into the upper plenum. + The US presented model areas considered most important for LOCA analysis of Rovno. f 1

f. . i a, r Both parties agreed that independent analyses of South Texas by the Soviets and of Rovno by the US of the same event at both Rovno and South Texas would be beneficial for understanding the safety of each other's plants. The two sides reviewed the details of the information request kit for LOCA and ATWS events prepared by US and clarification was provided as needed. It was agreed that the data needs were understood by both sides and that the data would be transmitted. if available, not later than March 1, 1990. Further agetement was reached on the variables for which results will be provided. Both sides agreed on the importance of man-machine interf aces in dealing with of f normal events and that common mode failures should be given adequate consideration in plant design. Further the two sides agreed that enhanced capability to deal with severe accidents including ATWS is desirable for future plants. The US presentation on ATWS summari:ed the operational experience which supported the' issuance of the ATWS rule for US plants. The background discussion included the Kahl multiple relay failures, the Salem ATWS event and the Browns Ferry partial scram system failure. The presentation also covered the importance of I.ey parameters (e.g., MTC) as well as design changes resulting from the ATWS rule. The Soviets presented preliminary ATWS calculation results using the DYNAMIKA code. The Soviets compared these results with

• ELAP5 MOD 1 calculations which yielded somewhat different results, particularly in the area of primary pressure.

A unique feature of the Soviet design which may impact ATWS response is the tripping of the Reactor Coolant Pumos on low' steam generator level. There was some discussion of j the sensitivity of the results to this feature, Both parties agreed to exchange necessary data to perform independent calculations of ATWS event. The Soviets presented their philosophy regarding the operator *n role in dealing with postulated accidents. Instructions to the operators are based on OPB-80 which contains rules for safe operation of plants as well as the limits. The chief engineer (a licensed operator) at the plant has the authority to override the operators' decisions with regard to the conduct of post accident operations. A particularly unique feature of the Soviet design is the incorporation of electrical inhibits which preclude the operators from over-riding automatic safety functions while certain parameters are within a prespecified range. [

? p i The US presented a summary of the philosophy for operator response during accident conditions. Unlike the Soviet approach the US designs do not incorporate features to inhibit operator intervention at any time during off normal conditions. The US approach for operator actions is based on symptoms which represent the status of six specified critical safety functions as opposed to event l based procedures. The US briefly discribed the steps the operators would be instructed to follow to deal with any off normal events. It was noted that the immediate operator actions were basically identical for both the US and the USSR approaches. Both parties agreed tha t consideratier should be given for dialogue in the areas of symptom based and event based guidelines for operator action, the degree of reliance on operator action for design basis events and the opportunities for operators to override automatic safety functions. Both sides also agreed that independent ATWS analyses for Rovno would be beneficial. The US presentation on Station Blackout '(590) traced the background beginning with the discussion of the site / design specific considerations regarding the likelihood of extended loss of offsite power, the reliability of the onsitw AC power system. and the capability of the plant to withstand an EBO. The ans. lyses of SBO do not require postulating any other simultaneous failureb. Further. it was noted that every plant's battery capacity would be suffi: lent to support essential DC loado for a minimum of two 5eurs. Until the generic issue on the performance of reactor coolent pump seals is resolved. the SBO analyses assume a leakage of 05 GPM per pump. US RG 1.155 and NUMARC-8700 (copies given by th US to the USSR) documents l were used to describe the key elements to be evaluated to determine the required SBO coping period as well as the i required analysis. The Soviets indicated that a total SBO l-is neither required nor analy:cd. Instead it is assumed that loss of offsite power coincident with failure of two diesels r.sn cecur but one diesel generator is still available to [ safely shut the reactor down. However, recently the USSR has begun to analy:e the plants' capability to withstand SBO events. The Soviets also indicated that they do not expect 'hc conctor coolant pump seals to leak excessively for several hours after loss of all seal cooling. Further the USSR is planning experiments to assess the pump seal l performance beyond 8 to 10 hours after loss of all seal i cooling. The Soviets also indicated that after reviewing RG l t 1.155 and NUMARC-8700 documents they would consider the desirability of conducting 5B0 coping analyses. The Soviets. in response to a US question, stated that L although USSR regulations require a 2 y. shutdown margin l- ~

ra ci ; ll ') v 4 L,'* 1 e-l ) 1 ) i (during refueling) to criticality without taking any credit for. control rod positionst in fact plant administrative l procedures for which a physicist is responsible (during 5 refueling) require a 5 % margin to criticality without taking credit for control rod position. Further, the most limiting core configurations are analyzed before fuel movement begins. For het shutdown conditions USSR regulations require that at least i % margin to criticality be maintainad. P AGREEMENTS AND CONCLUSIONS

1) Both sides agreed that common mode failures should be given careful consideration in the design and man-machine interface is important during off normal events.

2) The participants agreed to discuss preliminary LOCA and ATWS analysis results at the next meeting. 3) The Soviets will provide a detailed presentation at the next meeting with a number of examples on the role of the design features which inhibit operator intervention in off-normal co,nditions when selected parameters are within a ~ prospecified range. The participants also agreed to conduct preliminary discussion of the importance of various types of communication during off normal events. 4) The Soviets will present the analysis of, as well as procedural considerations for, steam generator tube rupture events at the nent meeting.

5) 'The participants agreed to discuss the ROVNO end the South Texas response to station blackout events at the next meeting.

Also, the Soviets will discuss probabilistic analysis of station blackout for ROVNO. t 6) The two sides identified written questions from previous meetings for which responses will be discussed at the next meeting. RECOMMENDATIONS FOR FUTURE ACTIVITIES The following subjects are proposed to be discussed at the next meeting (a) Operator's guidance for cooing with accidents taking into consideration specific design features. . Benefits and disadvantages of allowed actions of the operator during an accident. , 4._ Y' -{ k. Y N.I.' Y. ?. ? '~

l "., ' j7 h' 4 I. l( L Soviet information about the operator's guidelines relatec to the initiation of primary to secondary leakage. The philosophy of commun1' cation at all levels of j personnel actions. (b) The study of the plant black-out Questions related to probabilistic 'pproach to safety assurance in such conditions, as well as the questions related to reactor coolant pump seals; and elimination of leakage from the primary circuit. (c) Finali:ation of input data to analy:e LOCA and Wm ATWS. Consideration of preliminary results of the analyses and finali:ation of input data. (d) Responses to the questions on FSAR related to South Texas and ROVNO plants. The time needed to cover the proposed May work scope is estimated at seven working days. In addition, it was agreed that as part of the next meeting, tours of a US nuclear power station and the NRC Emergency Response Center are desirable. For the fall meeting, it is recommended that the use of passive decay heat removal system and guidance with regard to the use of nor.nal' station equipment for beyond design basis accident control be discussed by USSR. Also -ecommended for the fall meeting is the initiation of more detailed discussion on containment design, capability, 7 and philosophy.

m l.' r 1 J? L l I i d MEMORANDUM OF MEETING: WORKING GROUP 5 - MODERNIZATION /BACMFITTING i t A. EEEPE AND CONTENT OF DISCUSSIONS The main topics covered by the US and USSR participants were: 1 The USSR provided detailed information on several activities that are now underway or completed to assess operating i plants with regard to the need for backfitting. Ten presentations were offered of which six~were selected for l delivery at the meeting. The six papers given addressed the following:

1) a paper addressing improvements to the RBMK reactors to ensure their further operation at high e

reliability and safety levelst

2) a discussion of the VVER 1000 reactor using fault-tree analysis methods to improve dynamic stabilityg

3) a report on the results of PRA analysis for VVER 1000 reactors and the identification of potential backfit modifications, including a passive secondary heat sink for decay heatt

4) a paper discussing items approved and planned by Gonatomenergonad:or (GAEN) which are directed towards improving reactor safetyt

5) a report on methods and some results of probabilistic fracture calculation et pipeline components: and 6) a paper i

discussing backfitting proposals for VVER reactors. using the backfitting proposals for the Armenian power plant as an example. The USSR also provided some information on the remaining four papers which were not presented at the meeting. The US provided detailed information on the US program for the backfitting of operating plants. These presentations covered: 1) The history and principles of the programt O) The licensing process which establishes adequate protection margins

0) The key documents leading to a completed design and a plant licensing basist

4) The policy on safety goalst

5) activities used to monitor safety marginst and

6) the process used to control generic and plant specific backfits.

Entensive background documents were provided. B. AGREEMENTS aND CONCLUSIONS 1. Both sides agreed that this meeting was important and useful in obtaining a mutual understanding of the genceal approaches used in evaluating additional safety improvements

E. ,o. l a ?- L L [. i I F for existing nuclear power plants. These approaches were frequently discussed in terms of actual examples. r O. Both the US a.7d USSR have ongoing programs to moderni:e and to maintain safety margins in light of new information. 3. It was observed that the backfit programs of the USSR tend to concentrate on each specific reactor while the program of the US tends to backfit on a generic basis. i 4. The US and USSR noted that economic considerations are often important factors in making backfit determinations. The quantitative determination of these costs and the relationship to the gains in safety are Leequently subject to major uncertainties. For some propes M ehanges. quantitative analyses of risk reduction are not feasible. Thus. of ten backfit determinations mu.st be made on the basis of engineering judgment. 5. PRA studies provide un'ique and valuable indications of safety levels and weakness in design that may pose safety concerns..Both the US and USSR are using this analysis method to provide engineering insights that assist in identifying areas that may warrant backfitting.

However, neither country currently requires a full PRA for each plant.

6. A key aspect of backfit programs is knowledge of the level of safety established by the current licensing basis of each plant, and the actual level of safety that eMists day to day in each plant. Proper and consistent backfitting decisions depend on a continuing assessment of this t situation. As a result, activities to monitor the enisting l safety level relative to that required are essential. Particularly important in this regard are operational experience reviews, inspection activities, and research programs which include FRA studies. C. RECOMMENDATIONS FOR FUTURE ACTIVITIES 1 WG-5 believes the next meeting agreed to in the Second Protocol would be of mutual benefit, in order to review and discuss: I a) a recent generic backfi: including the associated analyses and justification, and the process used in terms of the identification of the safety problem, and the assescment, approval. and implementation of the backfit; b) a recent plant-specific backfit, including the associated analyses and justification, and the process used l 1

3 I l' in terms of the identification of the safety problem, and the assessment, approval and implementation of the backfiti and { c) other aspects of a backfit program which are of high mutual interest. s e l' 6 e i I: I l v l u i f I I ~> - l l i g' 0 $I

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I. i I L I l i l MEMORANDUM OF MEETING WORKING GROUP 9: DIAGNOSTICS, ANALYSIS EQUIPMENT AND SYSTEMS FOR SUPPORTING OPERATORS i I. THE EUBJECTS OF DISCUSSIQM By USSR i. Monitorino and Diaonostics System of Nuclear a Power Unit: The system of operating mode diagnostics for identification of fast emergency processes was described. A specific eHample (smonstrating the diagnostics algorithm, the structure of technical systems and sytem software was described.(Dmitriev, V.)

2. Encert ?vstams der Moniterine. Medeline and Eafe Doeration of Nuclear Power:

The paper described expert systems being currently developed in VNIIAES. The expert system for classical containment type is capable to deal with probabilistic expert assessments. The expert system of express-diagnostics has been implemented in the on-line mode as an intergral part of the operating mode monitoring system. Expert systems of other types for various purposes i were described. (Gorlin, A.)

3. Develeoment of Generic Systems of Fest Diaonestics of Spelear Pewer Blants: This paper described the requirements and limitations of generic systems of fast diagnoctics and the role of generic systems of fast diagnostics within the nuclear power plant monitoring and control system.(Lebedev, N.)

4. Develcoment and imolementation Excerience of the Generic System of Fast Diaonostics for the First Power Unit of Ionalina NPP This paper discussed an agreement with the developed requirements, implementation and operation experience and development prospects associated with the subj ect. (Lebedev, N.)

5. Fest Diaonestic Svstem of the Reactor Core and Main Ecuiement of VVER Durino Doerations The paper described an advanced multifunction i

diagnostic system comprising indivicual types of diagnostic and monitoring as subsystems: vibroacoustic monitoring, small leak diagnostics, detection of loose equipment itoms, monitoring of the equipment lifetime, etc. The system is integrated with the information subsystem of the general power unit control system.(Mitin. V.) s

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6. Diannestic System of the Nuclear Power Plant Eculement Lifetime with Cvelie Leeds:

This paper discussed the methodology of calculations of primary equipment metal thermally stressed conditions based on the data of the recording system of the power unit parameters during transients, diagnostic system hardware and

software, trial operation of the system at an existing nuclear power plant.

(Kashchenko, S.) 7 Reliability Projections of Unicue Nuclear Power Plant Ecuiement Under Cvelic Leads durina the Oeeratient The paper described the methodology to calculate the equipment metal damage potential under cyclic loads. The methodology is compared with the method of linear summing up of damages the incorrectness of the later for the given conditions was demonstrated. (Veresomskyi, V.) t The main topics covered by the US participants were A. Information Suceert for coerators: The US described the evolution of the Safety Parameter Display System (SPDS), SPDS evaluation criteria, major problem areas found in certain SPDSs, post-trio review recording equipment, post-trip review good practices, and annunciator warning systems. (Regan, W.) B. Simulater Histerve The US described the evolution of full-scope training simulators in the US. the characeristics and limitations of each major class of simulators, the features and major equations of advanced thermal hydraulic codes for simulators, and recent trends in simulation. (Raglin, K.) C. Simulater Certification Process: The US described the process for certification of simulation facilities including the standards, policy, regulations, and plans established by ANSI /ANS 0.5, 1985, Regulatory Guide 1.149 10 CFR SS.45(b), and NUREG-1058. The US also described the simulation facility inspection and the simulator operability tests. (Raglin. K.) D. Simulater Tvoes and Use in the USA: The US described the types of simulators in the US (including full scope simulators, basic principles trainers, concept simulators. part-task trainers, modular simulators, engineering simulators, and plant analy:ers), utility use of full scope simulators, USNRC use of full scope simulators, structure of modular simulators, and characteristics and uses ef engineering simulators and plant analy:ers. (Raelin. !'. ) 2% ..e s

1 L i l ? E. Evstems Acornach te Trainino: The US discussed the key elements of the systems approach to training, determining job performance needs through systematic analysis, training program improvements through program evaluation, and the purpose, process, and scope of the INFO accreditation program. (Regan, W.). f. Omerster Trainino and Licensino The US discussed the training of non-licensed operators, training of reactor operators, training of senior reactor operators, licensing of reactor operators and senior reactor operators, and requalification program for licensed operators. (Raglin, K.) G. _Arecedural Sumoort for Doerotorst The US discussed the even't-based emergency operating procedure structure prior to the Three Mile Island event, the structure of the newer symptom-based emergency operating procedures, the technical adequacy of emergency operating procedures, improvements to i make emergency operating procedures more understandable, and improvements to make emergency operating procedures more usable. (Regan, W.) H. EPRI Develooment of Exeert Systems: The US described the development of expert systems by Electric Power Research Institute (EPRI), including the potential benefits from such expert systems, expert system building tools, and various expert systems developed or being developed in efforts sponsored by EPRI. (Raglin, K.) II. AGREEMENT 9 AND CONCLUSTONot l 1. The first meeting of the working group proved l fruitful and contributed to better understanding of the approaches in each country in the areas of diagnostics, use of simulators, personnel training, and use of emergency operating procedures. O. The working group believes that further discussion of the above matters would be very useful and would contribute to a better understanding of the practices in each country. O. Full scope simulators are used for personnel training in both countries, but the use is much more widespread in the US. In the USSR, for personnel training purposes, a wide range of technical means are used including conceptual simulators and functional-analytical l simulators. 4 The use of engineering simulators or plant analy:ers is increasing in both countries in order to !I

l t i i. i [ t t analy:e potential emergencies and those which have occurred. t 5 The concept of plant diagnostics in the USSR is to use systems and means for early detection of equipment failures and transient prevention, while in the US more emphasis is placed on transient control and mitigation efforts. 6. At Soviet plants there is no safety parameter t display system (SPDS), although a number of diagnostic and information display systems provide functions similar to those performed by the safety parameter display systems. 7. Emergency operating procedures in the US are symptom-based, while in the USSR they are event-based. 8. It appears that general approaches to the training of operators are somewhat similar, although additional l inf ormation is necessary for a better comparison. i III. THE MAJOR RECOMMENDATIONS OF THE WORKING GROUP ARE: 1 1. Share experience in the areas of diagnostics and personnel training through contacts between US and USSR nuclear industry specialists and by the potential exchange of computer codes, algorithms, and methodologies, subject to the necessary approvals. 2. Consider the possibility of a separate visit during the next meeting in the US to the NRC Technical Training Center (in Chattanooga, Tennessee) for observation of safety parameter display systems and symptom-based ) emergency operating procedures. 3. Consider including in the Working Group 9 program a discussion of each country's efforts in the evolving area l of severe accident training and simulation. 4. Develop the program for future activities of Working Group 9 for 1991 and beyond at the next meeting. IV. PROPOSED FUTURE ACTIVITIES OF THE WORKING GROUF ARE: The proposed agenda for the next meeting agreed to in the second protocol is as follows: 1. Discuss operator support systems, including in-core and essential component diagnostics. Each country would provide additional detail of operator support avstems discussed at the initial meeting. s r., ..Q .' *nl. s ;sM.J.q,.. *= p,..,, e '. A5en.y.xnus *W,.% - c r.,. ....i.4.,, d,%6 :+'M'd sM OXMa* h. A

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2.. Discuss expert systems from'the point of view of 6 -

providing support for plant operators. 1 3. Discuss staffing and training of nuclear platit-personnel, including training programs and emergency l operating procedure training scenarios. 1 L. L l 4 Discuss modular simulation of nuclear plant systems. . i 9 )' l s t I l i B t 6 f I,

7-a ( I i L l Aenendix II: List of Particioants and Observere f L US Participants in Working Group C: Analysis of the Safety of Nuclear Power Plants in the USSR &nd the US: Co-Leader ) Thadani, Ashok C., Director, Division of Systems Technology, U.S. Nuclear Regulatory Commission Other

Participants:

i Tondi, Dominic, Section Chief. Electrical Systems Branch, Division of Systems Technology, US Nuclear Regulatory Commission Collins, Timothy E.. Section Chief, Reactor Systems Branch, Division of Systems Technology, US Nuclear Regulatory Commission Komoriya, Hideko, President, International Technical Services, Incorporated, consultant to the US Nuclear Regulatory Commission Observert Gorden Fowler, Office of International Programs USSR Participants in Working Group C: Analysis of the Safety of Nuclear Power Plants in the USSR and the US: Co-Leader: LUNIN, Gleb L., Deputy Director, Nuclear Reactors Department, I.V.Kurchatov Atomic Energy Institute I.V.KURCHATOV ATOMIC ENERGY INSTITUTE ASTAPHOV Sergey A. Senior Researcher KOSOU90V Konstantin B. Leading Researcher Soecial Desion Bureeu "Hvdrocress" FIL Nikolay S. Department Head LEGUNENKO Inna N. Engineer ALL-UNTON 9 TATE INSTITUTE ON RESEARCH. DESIGN AND ENGINEERING \\ ... ~.... r-

FE, t, r t Le (-'i f. 1 i Soviet Participants, Working Group 2 (Cont.) SURVEY "ATOMENERGDFROEVT" TAKH Sergey M., Chief Engineer NOVIKOV Gennadyi A.. Chief Engineer EPSHTEIN !saak M. Department Head l' o l' b.

p l 4 d t Ll i 1 l i L I 1 i US Participants in Working Group 5: Moderni ation/Backfitting 1 l Co-Leaders Heltemes, Clemens J., Jr., Deputy Director, Office for Analysis and Evaluation of Operational Data, US Nuc1dar 1 t' Regulatory Commission 1 Other

Participants:

o Cox, Thomas H., Section Chief. Policy Development and ) Technical Support Section and Branch, Office of Nuclear Reactor Regulation, US Nuclear Regulatory Commission i Observer: i Gorden Fowler, Office of International Programs USSR Participants in Working Group 5: Modernization / 1 Backfitting (Members identified by *) Co-Leader KORNIENKO, Arnold G., Deputy Chief Engineer. t All-Union State Institute on Research, Design and Engineering Survey "Atomenergoproect" (AEP) All-Union State Institute on Research. Desion end Enoineerino curvev "Atemenercoorceet" (AEP) GORELOV Yuri V. - Deputy Chief Engineer of AEP, Department in Gorky-City SHVYRYAEV Yuri V. Head of Department RYBACHEV Vladimir V. Head of Department KNYAZHESKAYA Margaret V. - Senior Engineer All-Union Research Institute for Nuclear Power Plant Omeration KAZAKOV Vladimir A. - Head of Department GETMAN Alexander F. - Head of Department ZHUDENKOV Vladimir V. - Senior Researcher SVIDENEEV Evgeny N. - Senior Researcher MAIDANIK Vitaly N. - Leading Reseracher o a D k f t'h f'.**.? hl:,, '] 9 ' ', f. N .R C.Q:.L s. 31 E s U d d $i$.fis 5 11.!dfi E h

s UEER Participants in Working Group 5 (Cont.) The UffM 9 tate Committee fer the Tucervinien of tJuelear Power safety SSORELOV Alexander N. Chief Specialist ISOUSTCH!N Wikolai N. State Inspector DVD Gidreerens 8ROGOV Michael F. - Head of Department Research__Develeewent Institute ef Fewer Enetneerine SPALDIN Victor D. - Heae of Laboratory Documents Enchanged e

... ;.... 5.. c I i l i US Participants in Working Group 9: Diagnostics, Analysis Equipment and Systems for Supporting Operators Co-Leadert t Raglin, Kenneth A., Director, Technical Training Center, Division of Operational Assessment, Office for Analysis and Evaluation of Operational Data US Nuclear j Regulatory Commission I i Other Participantst j William H. Regan, Jr.. Chief. Human Factors Assessment Branch. Office of Nuclear Reactor Regulation t Observert \\ Sordon Fowler, Office of International Programs USSR Participants in Norking Group 9: Diagnostics, Analysis Equipment and Systems for Supporting Operators i Co-Leadert DMITRIEV, Viktor M. Department Head. All-Union i Research Institute for Nuclear Power Plant Operations [ (VN!!AES) Other

Participants:

All-Union Research Institute for Nuclear Power Plant Operation i l VELTCHINSKY Vladimir I. - Laboratory Head f VEREZEMSKY Vladimir G. - Leading Researcher GORLIN Alexander 1. - Leading Researcher GOSTOMELSKAYA Nataliya N. - Junior Researcher 2HUKAVIN Alexander P. - Laboratory Head I KASHCHENKO Stanislav F. - Laboratory Head MATCHINA Zoiya G. - Engineer l !.V.KURCHATOV ATOMIC ENERGY INSTITUTE VALINUSHKIN Andrew E. - Senior Engineer { MU2HIL Alexander S. - Laboratory Head MITIN Valentin 1. - Laboratory Head

I L c RAK!T!N Igor D. - Laboratory Head KHAZANOV!TCH Igor M. - Senior Researcher I.V.KURCHATOV ATOMIC ENERGY INST!TUTE FRANCH KRYT!EV ! van 5. - Laboratory Head KU2 NET 5OV Uryi P. - Engineer DAN!LIN Vitalyi V. - Laboratory Head RESEARCH AND DEVELOPMENT INSTITUTE OF POWER ENGINEERING LEFEDEV Nikolai N. - Senior Researcher STRELKOV Boris P. - Laboratory Head SPECIAL DESIGN BUREAU "HYDROFRESS" NOVOSELOV Vladislav A. - Leading Designer PHYSICAL AND ENERGY INSTITUTE FETRENKO Alexander A. - Senter Researcher I l

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O i t Anmendix 111: Documents Exchanged by Working Group C ty US: Information Request Kit for LOCA & ATW5 Analyses Chapter 17 of NUREG-0460 Writeup on Determination of Initial MTC " Anticipated Transients Without Scram". W.E. Durchill NRC Regulatory Guide 1.155, August 1988 NUMARC-5700, "Suidelines and Technical Basis for NUMARC Initiatives Addressing Station Blackout at Light Water Reactors, November 1987 NUREG-1032 Evaluation of Station Blackout Power Plants. May 1995 NUREG-1C20, " Training Review Criteria and Procedures" Paper by James E. Knight, NRC, " Station Blackout". presented at NRC Information Meeting, April 18-CO, 1989 Implementaticn" By USSRt Description of Soviet Thermal Hydraulic Analysis Codes Six Documents Describing Input Data Needs for Each Analysis Code Module Computer Listing of Input Data for the DINAM!KA Computer Code for LOFW-ATWS & Description of Inputs i i Four Plots of Calculational Results for LDFW-ATW5: Power vs. Time Pressurizer Pressure vs. Timet Total Reactivity vs. Timet Mass in Steam Generator vs. Time; and i Nodalization Diagram for Analysis of ' South Texas The list of source data on the Eouth Texas

,%Dl.'. NPP g.that are necessary for the calculations of

.large leaks and ATWS using the following [. c + g,;I *omp06'E cpdes s " DINAMIKA j T h.* e ~- ' M2i id?A:.54MtT.anoC'rTVELv2i'-N4Bos'~JJ., :, TETCH, KANAL-4, c MAZ-1,

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I [ o i, i i f i Boeuments Enchanced by Workine Greve 5 i I By US: i r NRC regulation: " Revision of Backfitting Process for Power Reactors", Federal Reeister, Vol. 53, No. 10'8, June 6, 1988. t " Revised Charter--Committee to Review Generic Requirements", memorandum from Victor Stello, April 23, 1987. NRC Chapter NRC-0514 "NRC Program for Management of Plant-Specific Backfitting of Nuclear Power Plants", [ August 26, 1988. i \\ NURES/CR-3568, December 1983, "A Handbook for Value-l Impact Assessment" NURES/CR-4627 Rev. 1, "Seneric Cost Estimates" NURES/CR-3971, October 1984, "*A Handbook for Cost-Estimating" NUREG/CR-5236, October 1989, " Radiation-Related ( impacts for Nuclear Plant Physical Modifications" I' i Reports to the Honorable Tom Bev111 U.S. Congress. l from the Chairman, NRC, datedt March 10, 1989 March 9, 1988 l February 10, 1987 March 4, 1986 Subj ec t s Changes to Nuclear Power Plants Generic Letter No. 89-10, June 28, 1989 Safety-Related Motor-Operated Valve Testing and i i Surveillance - 10 CFR 50.54(f) Summary of CRGR Agenda Items NRC Bulletin No. 89-01, May 15, 1989, " Failure of [ Westinghouse Steam Generator Tube Mechanical Plugs" NRC Information Notice No. 89-70, November 1,

1989, l

" Potential Overpressuri:ation of Low Systems" CRGR Background Package for Meeting No. 162 Ret ' Service Water System Problems (9 separate Documents) t Packages Containing 123 Pages of Presentation on the i US Papers I .. o

o.. t 'O O l l i h I i I Py USSR t i "Probabilistic Safety Assessment in Support of Safety ? Improvement Measures for NPP with VVER-1000". I V. Shvyrysev "Some Aspects of Backfitting of State of-the-art Power Units with RDMK", V. Baldwin ? "First-Stage Measures on Reconstruction and Updating f of NPPs with VVER-1000 According to Results of Chernobyl NPP Accident Investigation and Mitigation", A. Sorelov " Methods and Some Results of Probabilistic Fracture I Calculation of Pipeline Components on VVER and RDMK-type NPPs", A. Setman " System Approach to Dynamic Stability Analysis of VVER-1000 Units", V. Zhudenkov "Backfitting of the First Generation of NPPs with VVER-440 on the Example of the Armenian NPP", Y. Gorelov US Request for Documentation: 1. Documents similar to those provided by the US, including Organi:ation charts for those organi:ations a. represented by meeting participants, the location of the participant within the organi:ation, and the relationship and responsibilities of the organization for backfit decisionst b. A group of documentation indicating how a new requirement applicable to a number of plants is created, approved, and implemented at various 4 l

.,_........v e e e f. i i I organi:ational. levels, from the ministry level down to and including the individual plant supervisor * (including supporting analyses and ( number and type of actions taken.) l 2. One reproducible copy of the full text of USSR paper numbers 1, 6, 7, and 8 when available. (Brief abstracts of these papers were provided at the j meeting.) I e i f 3 i t' I { I l l w is %4",,,. 4 4 p ",;1 %' ',; 'g. t ' 2, 21:S.,:s.n.d fbik Mi h % $ k W s k h M.i'-

o e Documents Dtchanced by Workine Greve # t By US: NURES 0999, " Guidelines for the Preparation of Emergency Operating Procedures" NURES 1 59, " Evaluation Procedures for Simulation Facilities Certified Under 10 CFR 55" NUREG 1 42, "A Status Report Regarding Industry laplementation of EPDS" NURES 1:58, " Lessons Learned from the Special Inspection Program for EOPs" NUREG/CR-3017 "Near-Term Improvements for Nuclear Power Plant Control Room Annunciator Systems" NUREG/CR-0997 "Computeri:ed Annunciator Systems" NUREG/CR-4797, " Progress Reviews of Six Safety Parameter Display Eystems" Regulatory Guide 1.8, " Qualification and Training of Personnel for Nuclear Power Plants" Regulatory Guide 1.134, " Medical Evaluation of Licensed Perscnnel for Nuclear Power Plants" Regulatory Guide 1.149 " Nuclear Power Plant imulation Facilities for Use in Operater License Examinations" !NPO E8-001, " Maintaining the Accreditation of Training in the Nuclear Power Industry" !NPD 85-000, "The Accreditation of Training in the Nuclear Power Industry" ANS!/ANS 0.1 1981, " Selection Qualification, and Training of Personnel for Nuclear Power Plants" ANSI /ANS 0.4 1993, " Medical Certification and Monitoring of Personnel Requiring Operating Licenses for Nuclear Power Plants" ANS!/ANS 7.5 1995, " Nuclear Power Plant Simulaters for Use in Operator Training"

i Documento Exchang;d Working Group 9: By USSR j 1. Monitoring and Diagnostics System of Nuclear Power Unitt The system of operating mode diagnostics for identification of fast emergency processes was described. A specific example demonstrating the diagnostics algorythm, the structure of techrical systems and sytem software was described.(Dmitriev, V.)

2. Expert Systems for Monitoring, Modeling and Safe Operation of Nuclear Powert The paper described expert systems being currently developed in VN!!AES. The expert system for classical containment type is capable to deal with probabilistic expert assessments. The expert system of express-diagnostics has been implemented in the on-line mode as an intergral part of the operating mode monitoring system.

Expert systems of other types for various purposes were described. (Gorlin, A.) D. Development of Generic Systems of Fast Diagnostics of Nuclear Power Plants: This paper described the requirements and limitations of generic systems of fast diagnostics and the role of gensric systems of fast diagnostics whithin the nuclear power plant monitoring an control system.(Lebedev, N.) 4 Development and Implementation Experience of the Generic System of Fast Diagnostics for the First Power Unit of Ignalina NPFt This paper discussed an agreement with the developed requirements, implementation and operation experience and development prospects associated with the subj ect. (Lebedev, N.)

5. Fast Diagnostic System of the Reactor Core and Main Equipment of VVER During Operation:

The paper described an advanced multifunction diagnostic system comprising individual typeu of diagnostic and monitoring as subsystems vibroacoustic monitoring, small leak diagnostics, detection of loose equipment items, monitoring of the equipment lifetime, etc. The system is integrated with the information i subsystem of the general power unit control system.(Mitin. V.)

6. Diagnostic System of the Nuclear Power Plant Equipment Lifetime with Cyclic Loadst This paper discussed the methoodology of calculations of primary equipment metal thermally stressed conditions based on the data of the recording system of the power unit parameters during transients, diagnostic system 5ardware and

software, trial operation of the system at an existing nuclear power plant.

(Kashchenko, S.) 7 Reliability Projections of Unique Nuclear Power Plant Equipment Under Cyclic Loads during the Operation: The paper described the methodology to calculate the equipment metal damage potential under cyclic loads. The methodology is compared with the method of linear summing up of damages; the incorrectness of the later for the given conditions l was demonstrated. ( Vere z ems k yi, :~V. ) m-.u ..-~.n...... ~w.....

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o o I TRIP REPORT FOR WORKING GROUP 2 { Official Travelers: A. C. Thadant Travel To: Moscow, USSR [ D. Tondi T. E. Collins i H. Komoriya (Contractor) Office: NRR Beginning On: December 1, 1989 Ending On: December 12, 1989 Meeting

Title:

Working Group 2 Meeting on " Analysis of the safety of Nuclear t Power Plants in the USSR and US" l Organized By: Joint Civilian Coordinating Consnittee for Nuclear Peactor Safety (JCCCNRS) i ABSTRACT This was the second meeting of JCCCNR$ Working Group 2 which is focused on the analysis of PWRs in the US and USSR. The main topics discussed at the meeting were: 1) the USSR and US philosophies with regard to loss of coolant accidents (LOCA); 2) the US philosophy with regard to anticipated transient without scram (ATWS) requirementst 3) data needs for possible US analyses of postulated LOCA t and ATWS events for the Soviet Rovno station and Soviet analyses of the same events for the US South Texas Plant; 4) each country's philosophy with regard to operator actions during off norwal conditions; 5) each country's philosophy regarding consideration of station blackout events; and 6) each country's i shutdown margin requirements during cold shutdown and hot shutdown conditions. l The participants also toured the Rovno Nuclear Power Station which is comprised of two operating 440 MWe VVERs, one operating 1000 MWe VVER, and one 1000 Mwe VVER in the early stages of construction. Highlights of the meeting are: 1) Both countries use essentially the same i philosophy with regard to LOCA considerations; 2) ATWS will receive more deliberate design attention in future reactor designs in both countries; 3) independent LOCA and ATWS analyses of each country's design by the other l country were planned and data needs were specified; 4) the Soviet philosophy regarding operator intervention includes the use of electric or mechanical j features to inhibit actions such as overriding an autcmatic initiation signal during the early stages of an event. The US does not use such inhibits. Also, Soviet emergency response is event oriented while the US uses a symptom based approach.

5) the Soviet did not consider station blackout a credible event because of their use of three independent emergency power supplies. However, they are now analyzing plant response to a postulated blackout. 6) Shutdown recuirements for both countries were somewhat different but of comparable ennnervatism. The next Working Group meetino will be bold in the US in Fay or June 1990.

j i l i

i l I i JCCCNRS WORKING GROUP 2 " ANALYSIS OF THE SAFETY OF NUCLEAR POWER PLANTS IN THF USSR AND US" TRIP REPORT i

SUMMARY

l \\ Frte December 1 to December 12, 1989 NRR staff members A. Thadani, D. Tondi, and i T. Collins met with representatives of the Soviet Union in Moscow, USSR. H. Komoriya, a consultant from International Technical Services also participated i in the meetings. This was the second meeting of JCCCNRS Working Group 2 which I is focused on the analysis of PWRs in the US and USSR. The main topics discussed at the meeting were: 1) the USSR and US philosophies witn regard to loss of coolant accidents (LOCA);ATWS) requirements; 3) data needs for possible US

2) the US philosophy with regard to anticipated I

transient without scram ( l analyses of postulated LOCA and ATWS events for the Soviet Rovno station and f Soviet analyses of the same events for the US South Texas Plant; 4) each country's philosophy with regard to operator actions during off nomal conditions; 5) each country's philosophy regarding consideration of station blackout events; 6) each country's shutdown margin requirements during cold shutdown and hot shutdown conditions; and 7) future activities in accordance i with the JCCNRS Protocol. The participants also toured the Rovno Nuclear Power Station which is comprised of two operating 440 MWe VVERs, one operating 1000 t MWe VVER, and one 1000 Mwe VVER in the early sta9es of construction. i Highlights of the meeting are: 1) Both countries use essentially the same l phtlosophy with regard to LOCA considerations; 2) ATWS will receive more deliberate design attention in future reactor desi9ns in both countries; 3) independent LOCA and ATWS analyses of each country s design by the other country l were planned and data needs were specified; 4) the Soviet philosophy regarding operator intervention includes the use of electric or mechanical features to inhibit actions such as overriding an automatic initiation signal during the early stages of an event. The US does not use such inhibits. Also, Soviet } emergency response is event oriented while the US uses a symptom based approach.

5) the Soviet did not consider station blackout a credible event because of their use of three independent emergency power supplies. However, they are now analyzing plant response to a postulated blackout. 6) Shutdown requirements for both countries were somewhat different but of comparable conservatism.

The next Working Group meeting will be held in the US in May or June 1990. The official memorandum of meeting for Working Group 2 which lists all aoreements, participants, documents exchanged, and recottnendations for future activities is included as Attachment 1. Additional details of the meeting discussions are provided below. LOCA AND ATWS PHILOSOPHY AND ANALYSES The meeting discussions began with a presentation by the Soviets on the I philosophy used for the analysis of loss of coolant accidents. The Soviets presented a discussion of analysis inputs, assumptions and acceptance criteria. We noted that the Soviet methods were essentially identical to the reouirements of 10 CFR 50.46 and Appendix K. The Soviets indicated a strong interest in i perfoming a large break loss of coolant accident analysis for a US plant (the

p [.. I 1 3 South Texas Plant) and having the US perform a similar analysis for the Soviet Rovno Plant Unit 3. Unit 3 at the Rovno Station is a 1000 MWe VVER (PWR). It i was decided that the design basis cold leg break (lar9e break) would be j analyzed. i i The US medo a presentation on ATWS requirements in the US includinq'e. summa a the operational experience which supported issuance of the ATWS Ru Design changes resulting from the rule as well as the importance of key parameters such as moderator temperature coefficient were discussed. An interesting recent ch,nge in requirements in the Soviet Union is that the MTC must always be i negative even at low power levels. l The Soviets presented results of preliminary ATWS calculations performed with f the DYNAMIKA code. The Soviets sad compared these results with RELAPS P001 calculations perfomed by the Finns and noted somewhat different results, i particularly in the area of primary pressure. We noted in reviewing the analysis results that the Soviet design includes a reactor coolant pump trip on low steam generator level. There was some discussion of the sensitivity of the 4 results to this feature, with the Soviets indicating little sensitivity. The US discussed its interest in perfoming a loss of feedwater ATWS analysis on the Rovno plant. The Soviets agreed to provide us the dats needed for such analyses. j For both the ATWS and LOCA analyses data needs documents were exchanged and it was agreed that necessary data should be provided to each side by March 1,1990. Preliminary analysis results could then be reviewed at a May or June 1990 i meeting in the US. We noted, however, a possible problem in obtaining the i necessary inputs for the South Texas Plant because of the proprietary nature of i some of the data. { OPERATOR RESPONSE UNDER OFF NORMAL CONDITIONS Both countries presented a discussion of the philosophies used in the development of guidelines and procedures for operator response to off nomal events. There are notable differences in the two countries approaches. For example, unlike the US the Soviets indicated that electrical inhibits are used to prevent the operators from overriding automatic safety functions while certain conditions exist. The specifics of these features were unclear to us however. From the discussions it seemed that pressure or temperature or some measureable physical condition in the reactor or containment was used to trigger l operator permissives. However, when we toured the Rovno station, it appeared that only timers were used to preclude operator intervention. Soviet operators at the Rovno station indicated that they consider these inhibits to be an aid to the operator. The Soviets agreed to provide further infomation on this topic at i the next neeting. Another notable difference in philosophy is the use of symptom based procedures in the US versus event based procedures in the Soviet Union. The Soviet philosophy depends heavily on the operators ability to identify the event in progress. The US approach is based upon symptoms which are representative of specified critical safety functions independent of any particular event, t

0 ) i i 4 f l l Immediate post event actions however were noted to be nearly identical for both countries. I STATION RL ACK0UT The US presented a discussion of $80 Rule requirements and the concerns which led to promulgation of the rule. The Soviets indicated that they have not given much consideration to $80 until very recently. The Soviet design uses three l independent emergency power divisions, one of which is always assumed available. We provided a copy of Regulatory Guide 1.155 and NUMARC 8700 both of which i provide guidance on US SB0 reouirements. The Soviets now plan to do some coping l analyses for Rovno, i t During our presentation the Soviets noted our assumption of 25 gpm per pump i leakage for reactor coolant pumps. They do not expect significant leakage for l many hours after loss of seal cooling. The Soviets are developing a test program to assess the performance of seals after an 8-10 hour loss of cooling. The schedule for these tests is not determined yet, j It is interesting to note that the auxiliary feedwater system in the Soviet l design uses all motor driven pumps. The US uses a mix of turbine. driven and motor driven pumps. It appears in general that the Soviet philosophy emphasizes i redundancy rather than diversity. There was agreement among all participants that more discussion of common mode failures was needed, i i SHUTOOWN MARGIN i i We requested that the Soviets describe for us their reovirements for shutdown margin during refueling and during hot shutdown conditions. We we.re told that i USSR regulations require a 2% shutdown margin.during refueling without taking i any credit for control rod positions. However, plant administrative controls i typically require a 5% margin without credit for control rods. For hot shutdown conditions USSR regulations require a 1% margin be maintained. We noted that in the US control rod position is credited in the shutdown margin recuirement. i t TOUP OF THE ROVNO STATION i q l Following our roundtable discussions in Moscow we traveled to the town of V.urnetsovsk to tour the Rovno power station. The station is comprised of 3 r operating reactors with a fourth currently under construction. Two of the operating units are 440 MWe VVERs and the third is a 2000 MWe unit. Unit 4 which is in the early stages of construction is also a 1000 MWe unit. The site was originally selected to host six reactors, but units 5 and 6 are now on hold pending the outcome of an environmental reassesssment. I During our discussions with plant personnel we learned that the station at one [ time experienced a complete loss of offsite power fnr 30 minutes. At that time o l only two units were operating. All diesels and other safety systems operated properly during the event. j i l l

1 5 Pe toured the control room at Unit 3 and the construction progress at Unit A. The control reom was located at just about grade level. Two operators were i " active" and two were " backup". This is roughly equivalent to a US control room with a shift superintendent, ! SRO and 2 R0s. Operator shifts 6re 8 hours each. There are 7 crews, six being operational and one in training at any time. The control room used lar9e CRT's and very small annuciators. However, the annuciator panels were almost completely dark We asked to see the equipment which would inhibit operator actions during an accident. The result was timers set for abou: 15 minutes located in cabinets in a room nearly adjacent to the main control room. Our tour of the unit under construction gave us limited insights. The construction phase was too early to see component layouts. We did examine major components which were stored outside with little protection. These included the reactor pressure vessel, pressurizer and steam generators. One particularly interesting feature was the separation of the diesel 9enerators for a given unit. Two of the three diesels are located in a building on one side of the reactor while the third is housed in a separate building on the other side of the reactor. We also noted that six cooling towers were discharging in a relatively small area close to the switchyard and inquired as to whether or not icing was a significant problem during the long winters. The Soviets indicated no significant icing pecblems. 1 i l l

p% " v I ATTACHMENT 1 i. s L j ME*aDRANBL'M Dr MEETING FOR WORVING GPOUP On ANALY$li, OF THE EAFETY OF NUCLEAR POWER PLANTE IN THE UEER AND THE US !. WORK!NG GROUP ECOPE AND CONTENT OF DISCUSSIONS i i The main topics discussed by the USSR and the US participants were ( i) The Soviet philosophy for loss of coolant accident analysis and the input data needs for the Rovno and South Texas plants for such analyses. O) The US philosophy of ATWS requirements including the histcry of the develpment of the ATWS rule and the input data needs for the Rovne and South Texas plants for the ATWS onalysis. 3) Each country's philosophy for operator actions during eff normal conditions. 4) Each country's approach to consideration of station blackout. 5) Each country's shutdown margin requirements during cold shutdown tnd het shutdown conditions. USER presented its LOCA analysis philosophy and proposed an exchange of data in the format specified in computer manuel documents. The USCR would provide data and input assumptions for Rovno for RELAPS MOD 2 analyses. The US would provide tho same for the South Tevas plant for 'Eoviet analyses using the TEfCH-M code. Actual data anchange was proposed to be accomplished by correspcndence. Preliminary enclysis results would be discussed at the next meeting and the inputs corrected as needed+then. This p*oposal was taken under consideration by US noting the difficulty of getting all the required data for South Texas as well as a proposal to issue a joint report. Poth parties agreed on the need to understand models used in the others computer codes in order to provide the proper input data. Poth perties agreed that the proposed LOCA to be analy:ed for Rovno should be a cold leg break located 650 mm from the RPV. The available ECCS should be 3 accumulators. O high pressure injection pumps and low pressure injection

pumps, two accumulators should discharge into the lower plenum and i into the upper plenum.

The US presented model areas considered most important fer LOCA analysis of Rovno, i

g v o j l t i Both parties agreed that independent analyses of South [ Texas by the Soviets and of Rovno by the US of the same event at both Rovno and South Texas would be beneficial for understanding the safety of each other's plants. { The two sides reviewed the details of the information i request kit for LOCA and ATWS events prepared by US and clarification was provided as needed. It was agreed that the data needs were understood by both sides and that the i data would be transmitted, if available, not later than ( March 1, 1990. Further agreement was reached on the l variables for which results will be provided. Both sides agreed on the importance of man-machine interfaces in dealing with off normal events and that common modo f ailures should be given adequate consideration in plant design. Further the two sides agreed that enhanced capability to deal with severe accidents including ATWS is desirable for future plants. i The US presentation on ATWS summari:ed the operational experience which supported the issuance of the ATWS rule for US plants. The background discussion included the Uahl i multiple relay failures, the Salem ATWS event and the Prowns Ferry partial scram system failure. The presentation also covered the importance of key parameters (e.g., MTC) as well as design changes resulting from the ATWS rule. The Soviets presentud preliminary ATWS calculation results using the DYNAMIMA code. The Soviets compared these results with FELAPS MODI calculations which yielded somewhat different results, particularly in the area of primary pressure. A unique feature of the Soviet design which may impact ATWS response in the tripping of the Reactor Coolant Pumps l cn low steam generator level. There was some discussion of the sensitivity of the results to this feature, Both parties agreed to exchange necessary data to l perform independent calculations of ATWS event. The Soviets presented their philosophy regarding the operator's role in dealing with postulated accidents. Instructions to the operators are based on OPB-00 which contains rules for safe operation of plants as well as the limits. The chief engineer (a licensed operator) at the plant has the authority to override the operators' decisions with regard to the conduct of post accident operations. A particularly unique feature of the Soviet design is the incorporetion of electrical inhibits which preclude the operatort from over-rading automatic safety functions while certain parameters are within a prespecified rango. 1

a e b The US presented a summary of the philosophy for operator response during accident conditions. Unlike the Soviet approach the US designs do not incorporate features i to inhibit operator intervention at any time during off [ normal conditions. The US approach for operator actions is based on symptoms which represent the status of six specified critical safety functions as opposed to event based procedures. The US briefly discribed the steps the operators would be instructed to follow to deal with any off normal events. It was noted that the immediate operator acticns were basically identical for both the US and the USSR approaches. Both parties agreed that consideration should be given for dialogue in the areas of symptom based and event based guidelines for operator action, the degree of reliance on operator action for design basis events and the i opportunities for operators to override automatic safety functions. Both sides also agreed that /,ndependent ATWS anelyses for Rovno would be beneficial. The US presentation on Station Blackout (SBO) t-aced the backgrouny beginning with the discussion of the i sitn/ design specific considerations regarding the likelihood of extended loss of offsite power, the reliability of the onsite AC power system, and the capability of the plant to withstand an SBO. The analyses of SEO do not require postulating any other simultaneous failures. Further, it was noted that every plant *s battery capacity would be sufficient to support essential DC loads for a minimum of two hours. Until the generic issue on the performance of reactor coolant pump seals is resolved, the SEO analysos essure a leakage of 05 GPM per pump. US RG.i.155 and NUMARC-9700 (copies given by th US to the USSR) documents [ were used to describe the Ley elements to be eveleatt-6 i determine the required SEO coping perico ew well an .ns required analysis. The Sovikts ind164ted that a total SBD is neit5er required nor 6.41r:ed. Instead it is assumed that loss of sffsite pcmar coincident with failure of two diesels sccur but one diesel generator is still available to .r-wly shut the reactor down. However, recently the USSR has begun to e.nalyze the plants' capability to withstand SDO events. The Soviets also indicated that they do not expect the reactor coolant pump seals to leak encessively for several hours after loss of all seal cooling. Further the USSR is planning experiments to assess the pump seal performance beyond 8 to 10 hours after loss of all seal cooling. The Soviets also indicated that after reviewing RG 1.155 and NUMARC-S700 documents they would consider the desirability of conducting SBO coping analyses. The Soviets, in response to a US question, stated that although USSR regulctions require c 0 '4 shutdown margin

I (during refueling) to criticality without taking any credit I for control rod positionst in fact plant administrative procedures for which a physicist is responsible (during l refueling) require a 5 % margin to criticality without taking credit for control rod position. Further. the most l limiting core configurations are analyzed before fue! movement begins. For hot shutdown conditions USSR regulations require that at least i X margin to criticality I be maintained. AGREEMENTS AND CONCLUSIONS

1) Both sides agreed that common mode failures should be given careful consideration in the design and man-machine interface is important during off normal events.

t 0) The participants agreed to discuss preliminary LOCA and ATWS analysis results at the next meeting. 7) The Soviets will provide a detailed presentation at the next meeting with a number of examples on the role of the design features which inhibit operator intervention in off-normal conditions when selected parameters are within a prespecified range. The participants also agreed to conduct preliminary discussion of the importance of various types of communication during off normal events, a) The Soviets will present the analysis of, as well as procedural considerations for, steam generator tube rupture events'at the next meeting. 5) The participants agreed to discuss the ROVNO and the South Te>tas response to station blackout events at the next meeting. Also, the Soviets will discuss probabilistic analysis of station blackout for ROVNO. 6) The two sides identified written questions from previous meetings for which responses will be discussed at the next meeting. RECOMMENDATIONS FOR FUTURE ACTIVITIES The following subjects are proposed to be discussed at i the next meeting: (a) Operator's guidance for coping with accidents 1 taking into consideration specific design features. Benefits and disadvantages of allowed actions of the operator during an accident.

y". 0 p.* L a t 1 L Soviet information about the operator's guidelines related to the initiation of primary to secondary testage. l The philosophy of communication at all levels of personnel actions. I l, (b) The study of the plant black-out l Questions related to probabilistic approach to safety. ) assurance in such conditions, as well as the questions related to reactor coolant pump seals; and elimination of t leakage from the primary circuit. (c) Fina11tation of input data to analyze LOCA and I

ATWS, i

i Consideration of preliminary results of the analysen 1 and finali:stion of input data. (d) Responses to the questions on FEAR related to I South Texas and ROVNO plants. The time needed to cover the proposed May work scope is estimated at seven working days. In addition, it was agreed l that as part of the next meeting, tours of a US nuclear power station and the NRC Emergency Response' Center are desirable. For the fall meeting, it is recommended that the use of passive decay heat removal system and guidance with regard to the use of normal station equipment for beyond design basis accident control be discussed by USSR. Also I recommended for the fall meeting is the initiation of more ) deteiled discussion on containment design,* capability, and i philosophy. { i i l 5 I 2 I I l I i l l r L

? l l 1 L List of Particinants and ObseFvers i US Participants in Workir,g Sroup 2: Analysis of the Safety of Nuclear Power Plants in the USSR and the US: Co-Leader: Thadani, Ashok C., Director, Division of Systems Tec hnology, U.S. Nuclear Regulatory Commission Other

Participants:

Tondi, Dominic, Section Chief, Electrical Systems i Branch, Division of Systems Technology, US Nuclear Regulatory Commission Collins, Timothy E., Section Chief, Reactor Systemo Branch, Division of Systems Technology, US Nuclear Regulatory Commission Monoriya, Hideko, President, International Technical Services, Incorporated, consultant to the US Nuclear Regulatory Commission Observers Gordon Fowler. Office of International Programs USSF Participants in Working Group 2: Analysis of the Safety of Nuclear Power Plants in the USSR and the US: Co-Leader LUNIN, Gleb L., Deputy Director, Nuclear Reactors Department, I.V.Kurchatov Atomic Energy Institute !.V.KURCHATOV ATOMIC ENERGY INSTITUTE ASTAKHOV Sergey A. Senior Researcher KOSOUROV Monstantin B. Leading Researcher Soweial Demian Bureau "Hvdroeress" 'FIL Nikolay S. Department Head LEGUNENKO Inna N. Engineer $LL-UNf0N STATE INSTITUTE ON RESEARCH. DESIGN AND ENGINEERING

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Soviet Participants,' Wori:ing Group : (Cont.). y BLRVEY " ATOMENFRSDPRDEPT " TAKH Sergey M., Chief Engineer. NOVIKOV Sennadyt.A., Chief Engineer EP9HTEIN 1saak M. Deper.tment Head [. r ( i l

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NP, I Documents Exchanged by Working Group 2 Sy US: Information Request Kit for LOCA & ATWS Analyses Chapter 17 of NURES-0460 Writeup on Determination of Initial MTC " Anticipated Transients Without Scram", W.E. Durchill t NRC Regulatory Guide 1.155, August 1988 ( NUMARC-8700, " Guidelines and Technical Basis i for NUMARC Initiatives Addressing Station Blackout at Light Water Reactors, November 1987 NURES-1032 Evaluation of Station Blackout i Power Plants, May 1985 NUREG-1220 " Training Review Criteria and Procedures" Paper by James E. Knight, NRC, " Station Blackout", presented at NRC Information Meeting, April 18-20, 1989 ( Implementation" By USSR Description of Soviet Thermal Hydraulic Analysis Codes Six Documents Describing 2nput Data Needs for Each Analysis Code Module Computer Listing of Input Data for the l DINAMIKA Computer Code for LOFW-ATWS & Description of Inputs l 4 Four Plots of Calculational Results for LOFW-ATWS Power vs. Timet I Pressurizer Pressure vs. Timet [ Total Reactivity vs. Time Mass in Steam Generator vs. Timet and Nodalization Diagram for Analysis of South Texas The list of source data on the South Texas NPP that are necessary for the calculations of large leaks and ATWS using the following i computer codes DINAMIKA, TETCH, KANAL-4, M A Z - 1,- SAOK, TVEL-2, NASOS.

,s 'l:u ,..,, o,', t ,c ( , p, i, ;., ) [9. ;g', 4 e, The Wescription'of computer codes for the analysts of i ~ operating and emergency conditions.of WER-type 7, reactors. - + 52'\\ i 1

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y J o ( l TRIP REPORT FOR WORKING GROUP $ Official Traveler: C. J. Heltemes Travel To: Moscow, USSR Office: AE00 t Official Traveler: T. H. Cox Beginning On: December 1, 1989 Office: NRR Ending On: December 12, 1989 Meeting Title and/or Affiliation: Working Group 5 Meeting on Modernization /Backfitting i Organized By: JCCNRS 1. Abstract The main topics covered by the U.S. and USSR participants were: The USSR provided detailed information on several activities that are now underway or completed to assess operating plants with regard to the need for backfitting. Ten presentations were offered of which six were selected for delivery at the meeting. The six papers given addressed the following: (1) a paper addressing improvements to the RBMK reactors to ensure their further operation at high reliability and safety levels; (2) a discussion of the VVER 1000 reactor using fault tree analysis methods to improve dynamic stabilityt ~ (3) a report on the results of PRA analysis for VVER 1000 reactors and the identification of potential backfit modifications, including a passive secondary { heat sink for decay heat; (4) a paper discussing items approved and planned by Gosatomenergonadzor (GAEN) which are directed towards improving reactor safety; i (5) a report on methods and some results of probabilistic fracture calculation of pipeline components; and (6) a paper discussing backfitting proposals for i the Armenian power plant as an example. The USSR also provided some information on the remaining four papers which were not presented at the meeting. The U.S. provided detailed information on the U.S. program for the backfitting [ of operating plants. These presentations covered: (1) the history and prin-ciples of the program; (2) the licensing process which estiblishes adequate i protection margins; (3) the key documents leading to a completed design and a i plant licensing basis; (4) the policy on safety goals; (5) activities used to monitor safety margins; and (6) the process used to control generic and plant specific backfits. Extensive background documents were provided. The USSR papers and the ensuing discussion provided information on the amount { and extent of generic backfitting on RBMK and VVER plants. The process for managing USSR hackfitting, including the methods and criteria for making j backfit decisions, remain to be presented at a later meeting. i The U.S. presentations focused on the fundamental principles and process used to manage and conduct backfitting. Discussion of specific generic and plant-specific backfits was planned for the next working group meeting in May 1990.

.I t =2-l Documents provided by both sides are listed in Appendices 1 and 2 enclosed. The U.S. also requested copies of four presentations not provided at, the time of the meeting. Reproducible copies of the Soviet papers (and English translations where available) and the U.S. presentation handouts, listed in l Appendices 1 and 2, are available from Ed $homaker, International Programs or f rom WG-5 members. 2. Overview of Information Obtained from U$$R USSR Process for Making Decisions on Mandatory Backfits The USSR process and related criteria for the identification, review and approval of generic backfits was not specifically presented. In fact, it was not,ed by a U$5R representative at one point that the process was "...so compli-cated that I don't know where to start." It seems clear that at least four organizations must approve or agree that a (generic) backfit is necessary the plant, the design organization, GAEN (the regulator) and the Minister of Atomic Energy. The normal process seems to be: (1) the plant identifies a safety problem; (2) the plant documents the safety issue and forwards it to the design organization for review; (3) the design organization reviews the issue; if they do not believe action is needed, the issue goes no further; if they do believe action is necessary, documentation of the issue is forwarded to GAEN for approval; (4) GAEN reviews the safety issues and either approves it or not; (5) for those issues GAEN approves, documentation is sent to the Minister of Atomic Energy who can issue a directive on the matter to the plant managers; and (6) the plant managers receive the instruction from the Minister and act accordingly. Evidently for plant 9pecific matters dealing directly with plant operation, GAEN can issue directives to plants through their regional representatives. For example, if an event or inspection discovered an abnormal condition, GAEN, through their representative, can write the station instructing them to analyze what went wrong and to propose corrective action. Further, GAEN indicates that if they discover a safety problem through inspection reports, they can write the Minister of Atomic Energy and " propose that the question, situation or condition be eliminated." The Minister, who is responsible for desig"n and construction of plants, then studies the matter. A proposal is then worked out" among the various organizations, approved by the Minister for implemen-tation, and sent to GAEN for their approval. This was described informally as an ongoing process. The discussion clearly reflected that the process for generic backfits involved many organizations; that consensus of all organizations was necessary; that all safety issues need not be sent to the regulator (GAEN) and could be delayed or held by either organization involved; that the process was complex, cumbersome, and slow; and that GAEN was the closest to being a central authority, but that no single organization had responsibility or oversight over the entire process.

m. 3 Approach for Backfit Decisions The USSR representatives did not identify the methods or criteria used to make backfit decisions, in fact, even the scope and definition of the term backfit M was not clearly defined ir, their system. It was indicated that backfit or change was generally referred to in the USSR documents as improvements, modernization or reconstruction, but in general their use of the term was consistent with our definition. It was clear that high importance was placed on the cost of the backfit and on achieving minimum impact on plant operations. Frequent mention was made i of cost and economic impact of changes and when examples of backfits were discusred, there was never a mention of any interruption of power operation. One example involved the first generation VVER 440 which was designed for a rupture of a 100mm pipe (with a 32mm flow restrictor), but not of larger pipes such as 200mm or 500mm. Subsequent design reviews resulted in the conclusion that it was not economically feasible to modify the plant to accept a rupture of a 500mm pipe. However., since an improved ECCS safety system to cope with a single ended rupture of a 200mm pipe was about the same cost as coping with the e rupture of a 10 Cam pipe, the DBA may be revised to a single ended 200mm pipe. Larger ruptures would not be considered "possible" for these plants. Design 7d studies are continuing on possible modification to the early 440's but no decisions have been made regarding implementation for the modifications discussed. One USSR Laper presented a fault-tree approach using component reliability values to study the dynamic stability for VVER 1000's. However, no actual decisions had been made using the analysis presented, although recommendations were developed. Probabilistic analyses are evidently made for selected cases butnosystematicorwidespreadug9ofsuchstudieswasindicated. It was stated that an overall goal of 10 probability of release beyond site ~ boundary has been established, but the methods of assessing and implementing this goal were not presented. Thers was high interest and many questions on the NRC's safety goal and the related staff activities, it seems clear that the USSR is attempting to use PRA assessment techniques in analyzing potential safety concerns, but efforts seem limited to date. One of the goals discussed informally was that the 1982 USSR safety regulations were to be met by all plants or equivalent levels of safety were to be provided. One presentation discussed the modifications that have been made to the RBMK reactors and a number of safety features called for in the 1982 regulations, but were not incorporateci. It was not clear even af ter discussion exactly what criteria or specific methodology was used to make the backfitting decisions, nor was it clear how the t'alance between cost and safety is made. The impression one gets is that the safety concerns directly associated with the Chernobyl accident were addressed, but other matters were not addressed with E an equal priority. For example, after Chernobyl, measures were implemented to eliminate the positive reactivity coefficient for the VVER 1000 plants (by inserting rods and reducing boron 65 a temporary measure and by going to a r three year 'uel cycle using new fuel) but a number of modifications including control rod modification to prevent rod sticking still were not fully r implemented. i

I I Extent of Backfitting in the USSR The USSR presentations covered a number of backfits (also called modernizations, reconstructions or improvements) that have been implemented or authorized on a generic basis. It was difficult to obtain a clear picture of the magnitude or impact of this activity. No lists or statistics were given indicating the overall number, type, applicability or status of authorized backfits. Informal discussion estimates were'that since Chernobyl, approximately 150 actions have i been authorized (of which approximately 100 are on RBMK's). It was noted that GAEN has approved about 50 safety analyses or improvements for implementation on VVERs. i r e These items were to be completed by 1993. The current frequency of backfit actions for the 1000 MWe VVER plants was discussed as three or four per year. The' USSR presentations focused, for the most part, on many safety improvements currently under study. Proposals have been developed for the VVER 440 and 1000 reactors, and for the RBMK's. The conclusion following discussions on these items, however, was generally that no decision had been made regarding implementation and that all, some, or none of the proposals discussed might be installed. 3. Soviet Presentations The Soviets proposed 10 papers for discussion and described each. We selected six papers considered to relate to process and methods of managing backfitting rather than specific technical solutions to plant-specific deficiencies in design or operation. We requested a copy of each of their 10 papers and received seven at the conclusion of the meeting, i The Soviet papers are described in order of presentation: USSR Report No. 3 - The Soviets reported on efforts to improve the RBMK design. Already approved changes include: (1) Core mechanical modifications and increased fuel enrichment to reduce the positive reactivity coefficient, (2) Increased insertion speed of 24 of the control rods, and (3) A number of organizational and procedural changes for both prevention and mitigation Several other changes are planned to bring the RBMK plants closer to the current j safety standard (GSR-82). No changes are known to be completely implemented at any plant. The objective is for all plants to either meet the GSR-82 standard or l-to attain an equivalent level of safety. l l' l I

r Thus, deviations from the current standard will be accepted, particularly those where it would be expensive to change the plants, such as: no containment l DBA LOCA is for 300mm pipe when max coolant pipe dia is 800mm lack of separation of safety system electrical cable lack of seismic, high wind, sandstorm resistance USSR Report No. 7 -- System Approach to Dynamic Stability Analysis of VVER-1000 Units, '.y V. Zhudenkov The definition of dynid: stability in the context of this paper was the measure of the capability cf che 9 tal plant system, including operating staff, to stay within safety limhsog c4nditions of operation. They considered both external (grid voltage or poe ' fluctuations) wf internal (turbine failure, equipment failure, control power failure, human failure) nerturbations. T The Soviets found that most unplanned events start with secondary side faults. It was noted that some of these events can be quite complicated, reflecting that the design emphasized safety and not operations, and that the regulating system for the turbine, feedwater and reactor is very complex. The paper presented several factors they consider important contributors to instability. These are: 1. Meeting conservative operating limits results in challenges to safety systems. 2. Complicated automatic control systems. 3. Multiple failures. 4. The need for better algorithms in computer programs to model core physics and thermal-hydraulic behavior. The work done in arriving at these conclusions was one of the first applications of fault trees using failure rates to a complete plant, as contrasted with individual system analysis. We asked whether the analysis led to any backfits that have been implemented. They stated that one change has resulted, an increase in the insertion speed of one control rod group in order to achieve a " set-back" power rather than a scram. The change was only a change of setpoint and control progra:nming no change of hardware was involved. Tha objective for the modification was improved reliability, not safety. 1 The change was issued or required by the Ministry of Atomic Energy; however GAEN required an analysis to demonstrate the proposal. GAEN then authorized a trial installation on one plant. After evaluation of the results, GAEN gave permission for the change at all plants. l l

I i USSR Report No. 2 -- Probabilistic Safety Assessment in Support of Safety Improvement Measures for NPP with VVER-1000, by Y. Shyyryaev This paper addressed Soviet work on the question "should older plants meet current standards? If so, to what extent?" The Soviets are attempting to reduce the potential for severe accidents, and feel it necessary to apply both deterministic and PRA methods as assessment tools. This work focused on the VVER 1000 plants and was done to test the risk reduction resulting from proposed changes. The changes being assessed by PRA methods included: (1) Improvement in scram - modification of safety system and increasing the number of control rods from 60 to 120 rods. (2) Possible rapid boron injection system - to serve as a redundancy to scram system. (3) Application of passive decay heat removal on secondary side. (A) Confinement of primary to secondary leakage to containment. PRA studies have been conducted based upon eight different initiator events, including loss of all AC power, loss of secondary heat sink, loss of main steam manifold, and steam generator tube ruptures. The highest probability (risk) was associated with loss of secondary heat sink. As a result, attention was being directed to a passive heat removal system attached to the secondary system ~ (basically a refluxing heat exchanger attached to the steam lines). Decay heat would be transferred to air, and inventory would be conserved. Air valves or steam operated valves would be used to eliminate power dependency. Either two or three such units would be needed. No decision has been made to backfit, although development and test activities continue. USSR Report No. 4 - First Stage Measures on Reconstruction and Updating of NPPs with VVER-1000 According to Results of Chernobyl NPP Accident Investigation and Mitigation, A. Gorelov This paper discussed the Soviet review of all other types of reactors following the Chernobyl accident, from the perspective of the regulator (GAEN). Several of the urgent and proposed future changes were described. These changes are not required at all plants. Gosatomenergonadzor (GAEN) decides implementation on a plant-specific basis. Urgent measures included: (1) Eliminate the positive temperature coefficient. The temporary measure was insertion of control rods at the beginning of core life and a reduced concentration of boric acid to hold reactivity, which reduces the positive reactivity coefficient. As fuel burns, control rods are withdrawn. A longer-term fix is a three year fuel cycle (1/3 core replaced each year) instead of two year cycle (1/2 core replaced each year). This change includes using a burnable poison in the fuel. Thus, a new fuel design is involved. Reactors are now on the three year cycle, i

p q (2) Modifications to control rod drives to correct observed failures to insert ( on scram. The specific problem was a design fault with the position indicator mechanism (a thread type mechanism developed high friction when corrosion was present). This condition resulted in three rods stuck in actual practice (out of the total of 61 rods). This problem is being i corrected over a two year period. They also completed analyses to demon-strate that several (number not provided) rods could stick and safe shutdown would still be achieved. (3) Use of charging pumps for ECCS injection - previously, pumps injected water during transients after system pressure decreased from 180 bars to 160 bars or at very low pressure (accumulators came on at 60 BARS and a i low pressure pump started at 23 BARS). Thus, the pressure range of 180 to 160 BARS was not covered. Use of charging pumps corrected this situation. (4) Automated sampling of offsite (30-40km) meteorological data -- a method not i used previously because of unreliable power supplies in remote areas. (5) Improvements in fire protection -- insulation and a spray cooling system for the turbine building roof structure, use of non-flammable turbine lubricating oil, and use of fire retardant cable insulation. These changes are among about 100 proposed or being researched. About 50 already developed are scheduled for implementation by the end of 1993.

GAEN, other ministries, and plant management all agree on the specifics of a change

'before it is ordered to be done. The change is approved by GAEN. Some plant-specific changes may be ordered by GAEN inspection personnel assigned to plant sites. We asked the Soviets for documents that would describe the process for initiating, developing, and imposing new requirements on operating NPP, both generic and plant-specific. GAEN indicated that such documents could be pro-vided. GAEN further indicated that they could order specific actions, e.g., that maintenance at all stations must be implemented during GAEN-approved procedures. t USSR Report No. 5 -- Methods and Some Results of Probabilistic Fracture L Calculation of Pipeline Components on VVER and RBMK l NPPs, A. Getman This paper described the use of PRA and deterministic analyses to determine the extent of radiation hardening of reactor vessel wall material, to examine the potential consequences of events ranging from leaks to explosive breaks, and to demonstrate from analysis using actual toughness measurements that the vessel i conforms to required safety standards. The Soviets described hardness measuring equipment that is lowered into the vessel during outages. As a result of their l analyses based on actual measurements of wall material after irradiation, this technique was considered highly successful. The Soviets have annealed several i vessels at five plants (seven vessels in all). Typically these vessels had been in service 12 to 16 years. l l 1 l

t l e .g. USSR Report No.10 -- Backfitting of the First Generation of NPPs with VVER-440 on the Example of the Armenian NPP, Y. Gorelov The Armenian station was an early VVER-440 (designed in the 1960's). The effort described by the Soviets was to evaluate what substantive and affordable backfits might be proposed to increase plant safety. A major consideration in backfit discussions was cost. When an improvement is proposed, the question seems to be "is it reasonable to do this, considering the cost?" Several changes were proposed and engineered, but only vessel annealing has been completed thus far. The modifications under study are: 4 1 1. Adding a three tier RHR system (high pressure, low pressure, and sprinkler), four tank accumulators with boron, and a three-train safety system for AFW. 2. Adding an acoustic emission system in the primary loop (in order to help provide additional safety margin to guard against rupture of the 500mm pipe), 3. Adding a reserve control room. 4. Changes in the compartment containing the primary loop in order to accommodate a DBA pipe rupture. The pipe rupture initially considered in the design was a 100mm pipe (with a 32mm flow restrictor), though the system has 200mm and 500mm pipes. They decided that treating the 500mm pipe break was simply not feasible because of the thickness and size of the cell that contains such a rupture. Coping with a 200mm rupture (single ended) was about the same cost as a system to cope with a 100mm pipe rupture. For breaks up to 200 mm (single-ended), no fuel rupture is expected. Therefore, only normal coolant activity would be in the compart-ment enclosing the primary coolant loop. The compartment would have a safety valve that was plumbed to a tall stack. The Soviets recognized that even if these proposed changes were incorporated, the older VVER-440s would not meet their own current safety standards, termed general safety requirements GSR-82. They use the leak-before-break principle to support their conviction of no sudden double-ended breaks of piping larger than 200mm. They also said that they have or will have leak detection sensors on large pipes in the containment. These modifications have not yet been approved for implementation. One approach under study is to incorporate all or a number of these proposals as l part of a new " building" that would be built in parallel with continued plant operation. l 4. United States Presentations Introduction, Overview, and Principles of Backfitting The fundamental questions pertinent to management of modernization-backfitting were posed, and additional relevant questions regarding backfit management l

.g. i i were presented and discessed. The definition of backfit was presented, generic and plant-specific were defined, the basis in U.S. regulations was described, and the overall process scope, content, and limitations were described. Overview of Licensing Process I This presentation described milestones in the process, the general content of an operating license application, the scope of NRC review, examples of the depth of review, a Safety Evaluation Report, and the content of an NRC issued operating license. This presentation focused on the work done to establish a finding of assurance to support a license issuance, and, by implication, a safety level of " adequate protection" at the time of licensing. Design Bases and Design Documents This presentation reviewed the process and documents involved in developing a verifiable design basis having a baseline measured from the time of initial license issuance. Safety Goal Policy This described the current policy statement of the Commission, its relationship to the concept of " adequate protection," and its relationship to the backfit rule's concept of " substantial additional protection." Also discussed werq the Commission's current limitations on use of the policy in the regulatory process. Programs to to Moni;or Plant Safety Margins This presentation discussed several programs of the NRC, licensees, interna-tional organizations, and insurance companies to monitor plant operational performance and to identify and address emerging safety concerns. The programs described operating experience reviews, various routine and special team inspections, specific issue inspections, events evaluations, research and i analysis activities, INP0 safety studies and plant evaluations, vendor and architect engineer safety studies, 0SART inspections, and state oversight activities. Generic and Plant-Specific Backfit Processes These two presentations described the NRC processes for managing the development and imposition of new requirements for licensees. Emphasis was on the systematic nature of the process as defined and controlled by procedures that are understood and used by NRC at all levels of management, and by both head-quarters and region personnel. In discussing the content of the processes, l the emphasis was on the regulatory analysis -- its content, conclusions, and j subsequent use by the staff. 5. Agreements and Conclusions From the Meeting l The specific agreements and conclusions, which were developed jointly after the presentation of papers, were as follows:

^ F l l t 1. Both sides agreed that this meeting was important and useful in obtaining I a mutual understanding of the general approaches used in evaluating additional safety improvements for existing nuclear power plants. These approaches were i frequently discussed in terms of a-tual examples. 2. Both the.V.S. and USSR have ongoing pro safety margins in light of new information. grams to modernize and to maintain I 3. It was observed that the backfit programs of the USSR tend to concentrate on each specific reactor while the program of the U.S. tends to backfit on a generic basis. 4. The U.S. and USSR noted that economic considerations are often important factors in making backfit determinations. The quantitative determination of these costs and the relationship to the gains in safety are frequently subject to major uncertainties. risk reduction are not feasible.For some proposed changes, quantitative analyses of Thus, often backfit determinations must be made on the basis of engineering judgment. 5. PRA studies provide unique and valuable indications of safety levels and weakness in design that may pose safety concerns. Both the U.S. and USSR are using this analysis method to provide engineering insights that assist in identifying areas that may warrant backfitting. However, neither country currently requires a full PRA for each plant. 6. A key aspect of backfit programs is knowledge of the level of safety established by the current licensing basis of each plant, and the actual level of safety that exists day to day in each plant. Proper and consistent backfit-ting decisions depend on a continuing assessment of this situation. As a result, activities to monitor the existing safety level relative to that required are essential. Particularly important in this regard are operational experience reviews, inspection activities, and research programs which include PRA studies, t 6. Recommendations for Future Activities l l WG-5 believes the next meeting agreed to in the Second Protocol would be of mutual benefit, in order to review and discuss: (a).a recent generic backfit including the associated analyses and justifica-tion, and the process used in terms of the identification of the safety problem, and the assessment, approval, and implementation of the backfit; j 1 l (b) a recent plant specific backfit including the associated analyses and l justification, and the process u, sed in terms of the identification of the safety problem, and the assessment, approval and implementation of the backfit; and (c) other aspects of a backfit program which are of high mutual interest. l l l i

m 11 I APPENDIX 1 - Documents Given to USSR By U.S. k ? NRC regulation: " Revision of Backfitting Process for Power Reactors," Federal Register, Vol. 53, No. 108, June 6, 1988. 6 " Revised Charter--Committee to Review Generic Requirements," memorandum from Victor Stello, April 23, 1987. NRC Chapter NRC-0514, "NRC Program for Management of Plant-Specific Backfitting of Nuclear Power Plants," August 26, 1988. NUREG/CR-3568, December 1983, "A Handbook for Value-Impact Assessment." l t NUREG/CR-4627 Rev. 1, " Generic Cost Estimates." NUREG/CR-3971, October 1984, "A Handbook for Cost-Estimating." NUREG/CR-5236, October 1989, " Radiation-Related Impacts for Nuclear Plant Physical Modifications." Reports to the Honorable Tom Bevill, U.S. Congress, from the Chairman, NRC, dated: March 10, 1989 March 9, 1988 February 13, 1987 March 4, 1986

Subject:

Changes to Nuclear Power Plants Generic Letter No. 89-10, June 28,1939 Safety-Related Motor-Operated Valve Testing and Surveillance - 10 CFR 50.54(f) Summary of CRGR Agenda Items NRC Bulletin No. 89-01, May 15, 1989, " Failure of Westinghouse Steam Generator Tube Mechanical Plugs" NRC Information Notice No. 89-73, November 1, 1989, " Potential Overpressurization of Low Pressure Systems" CRGR Background Package for Meeting No.162 Re: Service Water System Problems (9 separate Documents) Presentation Handouts: I Introduction to U.S. Presentation Overview and Principles of Backfitting Overview of Licensing Process Design Bases and Design Documents l Safety Goal Policy Programs to Monitor Plant Safety Margins Generic Backfits Management Plant-Specific Backfits Management

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APPENDIX 2: Documents Given to U.S. by USSR "Probabilistic Safety Assessment in Support of Safety Improvement: Measures for NPP with VVER-1000," V. Shvyryaev "Some Aspects of Backfitting of State-of-the-Art Power t Units with RBMK," V. Baldin "First-Stage Measures on Reconstruction and Updating of NPPs with Vver-1000 According to Results of Chernobyl NPP Accident Investigation and Mitigation," A. Gorelov " Methods and Some Results of Probabilistic Fracture Calculation of Pipeline Components on VVER and RBMK-Type NPPs," A. Getman " System Approach to Dynamic Stability Analysis of VVER-1000 Units," V. Zhudenkov "Backfitting of the First Generation of NPPs with VVER-440 on the Example of,the Armenian NPP," Y. Gorelov APPENDIX 3 - U.S. Request for Documentation: 1. Documents similar to those provid,ed by the U.S., including: Organization charts for those organizations represented by a. meeting participants, the location of the participant within the organization, and the relationship and responsibilities of the organization for backfit decisions; b. A group of documentation indicating how a new requirement applicable to a number of plants is created, approved, and implemented at various organizational levels, from the ministry level down to and including the individual plant supervisor (including supporting analyses and number and type of actions taken). 2. One reproducible copy of the full text of USSR paper numbers 1, 6, 7, and 8 when available (brief abstracts of these papers were provided at the meeting). 1

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c 1 l 4 l TRIP REPORT FOR WORKING GROUP 9 Official Traveler: K. A. Raglin Travel To: Moscow, USSR Office: AEOD Official Traveler: W. H. Regan Beginning On: December 1, 1989 Office: NRR Ending On: December 12, 1989 Meeting Title and/or Affiliation: Working Group 9 Meeting on Diagnostics, Analysis Equipment, and Systems for Supporting Operators Y Organized By: JCCCNRS 5 ABSTRACT The December,1989 meeting of Working Group 9 was the initial meeting of this working group. Additional details are available in the memorandum of the meeting, signed by the US and USSR delegation hesds on December 11, 1989. The i meeting was conducted at the I. V. Kurchatov icomic Energy Institute. The r discussions at the different sessions of the meeting were typically attended by sixteen personnel representing Soviet programs and two personnel representing US programs. Soviet participants in the working group came from l the All-Union Research Institute for Nuclear Power Plant Operation, the I. V. Kurchatov Atomic Energy Institute, the Research and Development Institute of Power Engineering, the Special. Design Bureau "Hydropress,*" and the Physical i and Energy Institute. q The agreed upon agenda for the meeting called for each side to make presentations in certain specific areas and for the other side to collect information and comment on these presentations. Soviet personnel made presentations on the following topics: Monitoring and Diagnostic System of l_ Nuclear Power Units; Expert Systems for Monitoring, Modeling, and Safe L, Operation of Nuclear Power Plants; Development of Generic Systems of Fast L Diagnostics at Nuclear Power Plants; Development and Implementation Experience of Generic Systems of Fast Diagnostics for Ignalina Unit 1; Fast Diagnostic System of the Reactor Core and Main Equipment of VVERs during Operation; Diagnostic System of Nuclear Power Plant Lifetime with Cyclic-Loads; and Reliability Projections of Unique Nuclear Power. Plant Equipment under Cyclic Loads during Operation. US personnel made presentations on the following topics: Information Support for Operators; Simulator History; Simulator Certification Process; Simulator Types and Use in the USA; Systems Approach to l Training; Operator Training and Licensing; Procedural Support for Operators; and EPRI Development of Expert Systems. l l Three of the papers presented by the Soviet side were provided in hard copy I format in English. Copies of two others were provided in Russian. Six of the l seven Soviet papers were presented in Russian with immediate translation into English. In some cases the only information obtained from Soviet papers l consists of the notes taken by the US participants during the presentation translations. All presentations by US participants were made in English with i immediate translation into Russian. Twelve copies of the presentation slides l 1 i l

E R L., L for each paper were previded to the Soviets. Despite the expected difficulties with the language barrier, a great deal of information was j obtained by both sides. Information learned about Soviet diagnostic systems is summarized later in this report. Additional meetings will be required in order to share and explain more detailed information on the topics of mutual ) interest. Following the meeting sessions in Moscow, a side visit to the Rovno slant was l made. Working Group 9 attention at Rovno was focused primarily on tie control room of Unit 3 (operating at full power) and secondarily on the remote ) shutdown panel and computer center, j i Conclusions and comments based on the meeting and the side visit to the Rovno plant are discussed below. Some of these comments go beyond the conclusions I agreed to for the memorandum of the meeting. 1. Full scope simulators are apparently used in both countries. 1 Present use in the USSR is believed to be only at a couple of national i training centers, but is projected to increase in the future. The USSR has signed' a contract with Singer Link-Miles for delivery of one or more VVER/1000 simulators. The projected increase in the USSR is not expected to match the l degree of full scope simulator use in the US. On the other hand, the use of concept and part-task simulators appears to be more extensive in the USSR. This comment is based on USSR reaction to US papers, rather than as a result of a formal presentation or direct observation. 2. Th'e use of engineering simulators or plant analyzers to analyze plant emergency situations seems to be increasing in both countries. It was not possible at this meeting to get any insight on the relative strengths of the advanced simulation models used in the two countries. 3. The optimal solution to operator information and procedural support systems currently perceived by the Soviets is significantly different from that currently perceived by the US. In the USSR there is great emphasis on thedevelopmentandimplementationofdiagnosticsystems(includingexpert system components) which will predict equipment failures, monitor and diagnose the existance and location of equipment failures, and monitor and correctly diagnose all aossible operational occurrences (called modes or-regimes). USSR emphasis on tie information systems will be to highlight the most important information, along with identification of the operational event, to the operator. Fresent USSR emphasis on emergency procedures is to develop event-based procedures which will adequately mitigate the results of the operational event diagnosed by the diagnostic systems. In the US there is great emphasis on the identification and clear display of important parameters which allow evaluation of the status of a relatively few critical safety functions. The status of thest critical safety functions are then used to determine necessary actions through the use,of the symptom-based emergency operating procedures. 4. More than 100 operational occurrences (modes or regimes) have been identified by the USSR and Finland as possible for VVERs. The book of event-based emergency operating procedures in the Rovno Unit 3 control room 2

i i + k contained about 45 procedures. This means that less than 50% of the i operational events considered possible by Soviet and Finish experts have emergency procedures it,the control room of an operating unit. Furthermore, discussions with the or-shift equivalent of the Senior Reactor Operator and Unit Supervisor and wit.h the Deputy Chief Engineer of the Rovno plant revealed that the steps in thesa 46 emergency procedures were not mandatory for the operators. These emergency procedures should, therefore, be described as i emergency procedure guidelines or recommendations. Plant officials did confirm that an effort was underway to develop new, event based procedures i which would spefify mandatory operator actions. 5. Plant operations personnel were asked what would happen if the emergency >rocedure for a correctly diagnosed operational event were being followed w1en a second, unrelated event ocurred. The answer given by the operational personnel was that in that case the additional actions taken would depend on the judgement of the operator. When the concept of symptom based emergency operating procedures was discussed with the Deputy Chief Engineer of the plant, he indicated that he had ncvar heard of the concept and that it sounded like a good one. 6. None of the diagnostic systems discussed at the meeting in Moscow were installed at the Rovno plant. These diagnostic systems are largely in the development or testing stages at individual units and will be installed in future plants. The developed systems will apparently be backfit at operating units. j 7. Soviet plants (if similar to Rovno Unit 3) make much greater use of computer driven CRT displays than originally anticipated. Information routinely scanned by the Reactor Operator and Turbine Operator is displayed one one of five CRTs in front of the desk for each operator. This information is evidently the essence of the required operational information. This information is provided by dual, redundant computer systems in the computer center for the plant. Operation without either of the computer systems is apparently administratively limited to about one-half hour. There is a possibility that some part of plant operations were under computer control. l 8. There is an operator inhibit feature which comes into play for a I period of 15 minutes when certain major plant parameters reach the initiation setpoints. During the 15 minutes, electronic interlocks are inserted which i prevent plant operators from interfering with the automatic functions of safety systems. Based on a look at an instrument room at the Rovno plant, it i appears that these inhibit interlocks are imposed on each system or subsystem I individually. In order to override these inhibit interlocks, an instrument l technician would have to go to the instrument room and attempt override of L each instrument drawer individually. It is unlikely that these safety system inhibit interlocks could be overridden during the time in which they are effective. There was no apparent procedure for override, nor any Soviet [ concept that such an action would ever be desirable. 9. Soviet plants have no safety parameter display system (SPDS). However, some existing instrumentation systems displayed on computer driven 3

l i i information displays provide some of the same or similar functions as those associated with SPDS. Additionally, the results of various diagnostic systems i (once implemented) dis > layed on control room CRTs should provide even more l similar functions to tie US SPDS.

10. Based on Soviet reactions to US presentations on the training of plant operators, it appears that the general approaches to training are o

somewhat different. Additional discussion and/or observation will be j necessary to quantify similarities and. differences. During the later stages e of the meetings in Moscow, one of the Soviets indicated that a high level l directive had just been received. This directive apparently required actions to upgrade Soviet emergency operating procedures and training programs and to structure the new approaches more along the lines of current practices in the US.

11. There is great interest (and apparent willingness on the part of the Soviets) to exchange computer codes, algorithms, and methodologies for i

diagnostic systems and other computerized expert systems.

12. There is mutual interest in future discussion of each country's efforts associated with training and simulation in the area of severe accidents.

13. There is substantial Soviet interest in modular modeling of nuclear plant systems, such as that done by the Electric Power Research Institute (EPRI).

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14. The concept of symptom based emergency operating procedures used in conjunction with safety parameter display systems is still somewhat obscure when discussed in general terms at a conference table.

The optimum method of showing the use and relative merits of this combination of operator aids is considered to involve a separate Soviet visit (of appropriate personnel) to the NRC Technical Training Center for direct observation of carefully orchestrated scenarios on NRC controlled simulators. DATA FOR REMAINING COMMENTS l The data for the remaining comments of the Working Group 9 trip report came from Soviet presentations made during the meeting, from notes taken during the meeting, and from the Soviet papers which were provided in English. This composite data has been summarized and then integrated as much as possible in order to establish the best overall perspective. Some of the terms and gramatical structure have been left as they were provided in the literal translation of Soviet papers or comments. Consequently, the wording may seem a little awkward occasionally. BACKGROUND OF SOVIET DIAGNOSTIC SYSTEMS The use of diagnostic systems at the plants for improving operator actions is considered a tool for enhancing plant safety. Three different types of systems for monitoring of plant equipment. Systems of the first type are used 4

o c to identify equipment failure. These are called Diagnostic Systems to Monitor Fomation of Primary toop Metal Defects. Systems of the second type provide i continuous diagnostic monitoring of plant equipment-using special sensors to identify defects and determine deviations. These are called Acoustic Diagnostic Systems.' Systems of the third type provide mode diagnostics for l different operational modes. These are called Mode Diagnostic Systems. r' VVERs were designed more than 20 years ago. It was originally felt that the systems were designed with such high quality that diagnostics were not i necessary. Lessons learned as a result of serious events have obliged the Soviets to expand the diagnostic philosophy. Initial progress was somewhat t slow because of early problems with the availability of computers and high quality programmers who could develop reliable codes. There is, however, a reactor in core monitoring system which is presently in place at all VVERs. l It provides for early monitoring of core characteristics (such as power density distribution and fuel burnup) and primary circuit functions, for t maintaining an archive of certain information, for identification of faulty i sensors, and for determining monitoring errors. The Soviets saw the possibility of in core noise analysis for early detection of abnormalities (neutron noise, pipe vibrations, in core instrumentation, primary circuit oscillation, etc.). They were primarily interested in detection of local boiling and used a Rhodium self powered detector. They discovered a prompt neutron component used for neutron monitoring, which can i in turn be used to detect local boiling in VVERs. As USSR nuclear unit power increased was from 300 to 1200 MWe, the number of [ measurable parameters-increased about 6 times and reached about 1000 analog and 1000 discrete parameters for some plants and seseral thousands for others. The process of determining the cause of a malfunction became more complicated when the shutdown system was activated. It was nearly impossible to distinguish the cause that triggered the signals from the effect of the sequence of signals without the use of special diagnostic systems. Additionally, over-stressing of operators was a major Soviet concern. Data from industrial psychologists showed that the operator data processing rate goes from the normal 45 bits per second to 0.5 sits per second under high stress..It was considered imperative to install new systems which could sift through large amounts of data and provide operators with the most pertinent subset of this data. The Soviets believe that this processed subset of all the data will then provide operators with quality and timely information to assist rather than complicate the decision making process and that mode diagnostics will allow for monitoring and analysis of transient and emergency conditions in real time. DIAGNOSTIC SYSTEMS TO MONITOR FORMATION OF PRIMARY LOOP METAL DEFECTS l Diagnostic Systems to Monitor Formation of Primary Loop Metal Defects consist 7 l of the following: 1. System of Acoustic Emission and High Frequency Acoustic Noise l 5 L l

~ Monitoring; ) 2. System of Humidity or Moisture Content Monitoring; and 8 3. System for Monitoring Acoustic Fields outside of Equipment, i These systems provide for monitoring of the generation of and propagation of i' metal defects, for detection of leaks, for detection of loose parts, and for monitoring of RCP bearing conditions. Primary data used in calculations by these diagnostic systems include acoustic emissions and high frequency j acoustic noises, humidity level, and microphones, i Previous information came from design documentation, inspection data, and maintenance history. This information was not enough to estimate equipment service life. Thermal cyclic loading is considered to be the dominant factor i in determining design service life expiration. From an operational standpoint, J residual service life expiration is characterized by metal damage under cyclic loading. Data on metal damage and equipment stress-strain condition is obtained using a continuously monitoring diagnostic system. This system is being developed at the All Union Research Institute for Nuclear Power Plant Operation (VNIIAES) and is based on computational procedures for temperature and stress analyses of metal in structures or equipment under study. Information is gathered about changes in thermal physical parameters. The l information is validated and processed in order to eliminate redundancy. Stresses are calculated based on coolant temperature, pressure change, and existing stress at time of construction. The sequences of stress change cycles are calculated based on the equipment operational history. Metal damage at cyclic stress conditions and metal longevity are then calculated. The difference between the limiting damage value and the current value is considered to be residual service life. Processed information enters into a diagnostic system to obtain data about equipment stressed condition and to estimate residual service life. The system is being installed at the Kalinin station and should be operational in 2-3 years. ACOUSTIC DIAGNOSTIC SYSTEMS Acoustic Diagnostic Systems consist of the following: 1. System for Monitoring of Elements and Components of RCPs; ) 2. System for Ultrasonic Monitoring of the Reactor (Vessel, Vessel Cover, and Control and Safety Rod Shrouds); 3. System for Monitoring of Vibration of the Reactor Vessel and RCPs, I of Primary coolant Pressure Pulsations, and of Reat. tor Neutron Noise System l for Detection of Loose Parts; and 4. System for In-Reactor Neutron and Temperature Noise Monitoring System for Monitoring of Primary Coolant Radioactivity Fluctuations Acoustic. These systems provide the following functions: monitoring of RCP parameters; ultrasonic testing of reactor, reactor cavity, and vessel upper internals; detection of unacceptable vibrations and vessel movement (using out of core sensors on reactor cover); detection of local boiling in the core, detection of loose parts, and free parts (using acoustic signals >100 kHz and signals 6

[ L I j <20 kHz); monitoring of coolant flow rate changes and coolant flow; and monitoring of primary piping, steam generators, etc. Extremely low magnitude signals are used in the detection of local boiling. Apparently the regular signal of about 10 EE -11 changes to about 10 EE 9 when there is boiling. Primary data used in calculations by the various Acoustic Diagnostic Systems i include numerous parameters for monitoring conditions of RCPs (vibrations, j velocity of rotation, sosition of bearings, coolant pressure pulsations, acoustic fields, and tiermal engineering parameters) and various process noises of the. reactor facility (vibrations, coolant pressure pulsations, in-reactor and out of reactor noises, in reacts,r temperature noises, primary coolant radioactivity fluctuations, and acoustic signals), i Soviet plans for the near future call for the use of several diagnostic systems (conventional in structure) to perform a number of related tasks. Small leaks are monitored through the use of acoustic noises. Foreign objects 1 (loose parts) are identified through the use of acoustic noises. Equipment vibration is monitored for fault determination. These systems allow for determination of the existence and location of faults based on signal strength. Vibration monitoring involves a spectral analysis. Each peak on an X-Y graph identifies some plant component. A drift or shift in the signal beyond some boundary indicates a problem. The type of fault is 1 determined by experience in operating the diagnostic system. [Perhapslike sonaroperators.) MODE DIAGNOSTIC SYSTEMS The Mode Diagnostic Systems consist of the following: 4 1. System for Monitoring of Normal, Transient Neutron Physical, and Thermal Hydraulic Characteristics of the Core Coolant Circuit; 2. System for Recording and Analysis of the Sequence of Rapidly Progressing Events during Emergency and Pre-Emergency Modes; l '3. System for Monitoring of Primary Coolant System and for Primary to Secondary Leaks; and 4. System for Monitoring of Residual Lifetime of Vital Reactor Facility Components. Primary data used in calculations by the various Mode Diagnostic Systems include the following: temperatures, pressures, pressure drops, flow rates, in-core neutron flux, out of core neutron flux, power distribution, fuel burnup, control and cutoff valve positions, motor circuit breaker positions, boric acid concentration, chemical composition of primary coolant, radioactivity of water in primary and secondary circuits, and turbine generator electrical load. Mode diagnostics were not part of the original designs. Their development became necessary because of increasing details associated with plant systems. As a result of these details, there is a large amount of information with which operators must cope (several thousand signals). It was necessary for the 7

~ L. j. u p USSR to create a system to screen all available information and then provide a f subset of this information to the o)erator. The operator could then L understand the situation and take tie proper action. There are two subsystems which monitor critical parameters and identify [ emergency modes. This is done by comparing the actual process results with the process results predicted by math models. The system has two parts. One t part is located in the information monitoring center (Computer Center) and uses large mini or mainframe computers for processing the math models. The i other part is a database of plant emergencies and actions. The database is complemented continuously by input based on plant response. Many sets of real and computed parameter traces have led to a good math model which adequately describe plant response. The Express Diagnostic Expert System (EDES) is an on-line system for automatic identification of emergency regimes at the earliest possible stages and for aroviding information about the emergencies to the operator. The task solved )y EDES is a classification or pattern recognition task. Information from sensors is used to establish normal or baselined conditions. Deviations from the baseline indicate emergencies. There is a unit which defines the signature of the emergency. In case of an emergency situation, the diagnostic system coepares actual transient response with that predicted in the models, A comprehensive list of more than 100 possible types of emergency operations (regimes) has been developed by technology experts in the USSR. A similar list developed by similar experts in Finland led to essentially the same list, such that the USSR and Finland feel that the list is sufficiently valid and complete. A quality mathematical model of emergency regimes was developed using the physical processes and strength characteristics of VVER-1000 units. Technology experts made a careful analysis of all of these emergency operations on the list and then selected the most characteristic parameters or symptoms for each emergency operation. Although about 1,000 parameters were available for each possible regime, the number of parameters considered critical to diagnosing the regime were 4-8. Different regimes are characterized by different sets of parameters. There is some existing error in instrument indication and in the mathematical model (plus or minus some value). Therefore, it was necessary to develop more complex characteristics than just the instantaneous value of a given parameter. l l There are six characteristic types of operational parameter behavior: rise, drop, local minimum, local maximum, sharp rise with stabilization at a new level, and sharp drop with stabilization at a new level. The parameters are l also indicated with the actual value. This description of parameter behavior has been adequate, increased system performance, and has significantly reduced L since each type of behavior is determined on the basis of no more than three L time points, i 8 l l l l

E. l O l I l l It was also considered necessary to take into account not only an error in a l L transducer's ir:dications, but also the complete failure of a transducer. L Diagnostic system. design, therefore, makes it possible to recognize a regime by (N 1) symptoms where N is the general number of symptoms describing the regime. There is a need to do the diagnostic work in real time. For rapidly i progressing events this is considered to be within 10 seconds. These i difficulties were resolved such that much of the identification work could be done in advance by using an expert system logic tree.. The system algorithm is divided into statistical and dynamic parts. "he statistical subsystem uses the base of regime expert descriptions to automatically build a regime recognition tree for use by the dynamic system. Using this recognition tree, it is practically impossible to include in the list of diagnoses an incorrect one. i The pattern recognition uses the " Statistical Least Damaged Method," since the expert system may have failed to identify the precise transient on the first try and will continue to determine recognition of the event. As a result, the dynamic sybsystem often generates lisft of diagnoses which are too long. On the final stage of work, another stricter function of similarity is applied. The operator then receives this product, a restricted list of diagnoses, whose similarity to the reference regime description is higher than some definite threshold. This system was written in the C programming language, has been fully tested in the laboratory,.and has been installed at the Kalinin station (WER/1000). DIAGNOSTIC SYSTEMS AS OPERATOR AIDS The Soviets plan to achieve improved operator actions through training in the use of diagnostics (both general and specific OJT), professional studies of human factors issues, and training on simulators. .The optimal operator support system is considered by the Soviets to include a local support systems using both special instrumentation (acoustic diagnostics, metal state diagnostics, etc.) and special algorithms (such as margin against DNB); a common overall computer operating support system; and a system for monitoring and predicting the status of eauipment. Work on the Common Computer Operating Support System (CCOSS) development and introduction of this system at a nuclear plant has been carried out since 1977. The purpose of CCOSS is to quickly and correctly determine the location L and cause of malfunctions and faults in all the basic engineering systems at I an early stage of their initiation, to display the diagnostic results, and to L give the operator the necessary recommendation on how to localize the fault. I A number of design features are considered by the Soviets to be necessary. CCOSS must have an efficient method of on-line information retrieval. It should be based on standard hardware instrumentation and the Information and Computer Aided System (ICAS). It must be a global diagnostic covering the l-entire. facility. It must be able to process all parameters sent to the ICAS. The system must react only to a change in status such that the operator is not 9 e

l .o overloaded, it must take into account both the failure of a detector and the superimposition of the detector failure onto an engineering failure and still be able to conduct the diagnostic, it must be universally adaptable, allowing 'i for upgrade or replacement. Some difficulties projected by the Soviets in the full development and implementation of CCOSS include the high number of input and output parameters, the strong interconnection between parameters (much . feedback), the current lack of sufficient experimental and statistical information, and the possibility of the initiation of multiple equipment failures coupled with a detector failure. l i 4 h 10

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+ TRIP REPORT BY GORDON F0WLER Official Traveler: G. Fowler Travel To: Moscow, USSR Office: IP Beginning On: December 1, 1989 Ending On: December 12, 1989 Organized By: JCCCNRS Observations on the substantive aspects of the working group meetings are covered in other reports. The purpose of this report is: to identify problems which arose and their resolution (" lessons learned"); discussions with others; and general aspects of the side trip to Rovno. 1. Problem: Familiarity with the USSR: Except for one member and the interpreter, no one on the delega, tion had been to the USSR before. This unfamiliarity was compounded by the fact that the delegation would be there in winter. Solution: A three-hour meeting was conducted for the delegation on the Soviet nuclear power program, Soviet customs and Moscow weather. An important compo-nent of the session was advice on what to bring. The seminar was useful, and others will be given for subsequent departing delegations. e 2. Problem: Obtainino Visas: The invitation from the Soviets did not arrive at NRC until two days before scheduled departure. This necessitated one round trip to the Soviet Consulate by car that day and two round trips the next day to obtain the visas. The problem arose because nearly a week was lost when the Soviets twice tried unsuccessfully to transmit the invitation. It is clear that the message did not leave the USSR because the Soviet Embassy in Washington also did not receive the message. The difficulty in getting invitations and visas has been a chronic problem in arranging visits to the USSR. Interim Solution: We were able to communicate by phone with the Soviets on the efforts to transmit the invitation because of twice-weekly scheduled telephone calls to Moscow. When it became clear that there was one last chance before i the visit would have to be postponed, the Soviets re-sent the invitation by all available means (telex, cable, fax) to both the NRC and the Soviet Embassy. Long-Term Solution: There does not appear to be any likelihood that the requirement for a formal invitation will be removed in the foreseeable future. Therefore, the aim is to obtain the invitation early and ensure adequate communications. We are addressing the former aim by planning not only the schedules but also the agendas of upcoming meetings at the beginning of the year. We are addressing the latter aim by using redundant communications. 3. Problem: Document Exchance: There has been no fully satisfactory means for providing to the Soviets the documents which are to be exchanged in advance of the meetings. This was true for WGs 2 and 5. In one instance, there was not enough time to deliver the material, given the state of the mail service with the USSR and the absence of an individual travelling to the USSR who could i

o' 4 2-i take it. In'the other instance, the material was not conveyed from one Soviet l official, to whom it had been given at the October 1989 Protocol meeting, to another. In addition, duplicating machines are not readily available in the USSR. Solution: The solution to the problem of minimizing unreliable document transfer has two parts. The first is to have the documentation available well in advance (two months in advance, according to the 1988 Protocol, a ( period which is being shown to be unrealistically long). The situation has improved in that the U.S. Postal Service now has a four-day delivery service to Moscow, which did not exist before the December meeting. The second part of the solution is for the WGs to take as many copies of the materials to the meeting as they will need. 4. Problem: Lunch Schedules: The need to travel from Kurchatov to a restaurant for lunch each day shortened the work days. This was a two-hour p excursion. An hour was needed to board the bus, travel to and from the restaurant and check coats. (The members of the U.S. team ate without their counterparts, so continued discussion over lunch was impossible.) Another hour was needed-to finish a four-course meal. Interim Solution: We asked for only two of the four courses to be served. i This cut about thirty minutes from the lunch period. There was no provision for having lunch on the premises. .i Long-Term Solution: We will look into using the lunch room used by the Kurchatov employees. If this creates security problems for the Soviets, it might be possible to have a lunch delivered to a common room. 5. Problem: Travel to Rovno Nuclear Power Plant: The Soviets had originally planned for the delegation to take the train to the Rovno nuclear power plant, a 24-hour ride each way. Only because we had communicated regularly by phone with our counterparts did we learn of this. Interim Solution: We objected strenuously to this onerous travel schedule. l The Soviets then were able to provide air transport to the nearest city, and bus transportation the rest of the way. i I 6. Problem: Word Processing System: To our surprise, the Soviets had two IBM-compatible computers at the location of the working group meetings, with i. the three types of disk drives (hard, 51/4" an 31/2"). This would have been of great benefit had the laptop computer we took with us and the Soviet computers had the same word processing software. B<.ause we had prepared the agenda and an outline of the meeting memorandum on our word processor (DisplayWrite), and we knew nothing of their processor (ChiWriter, as it turned out), we developed i draft reports on the meetings using our computer. The secretaries provided to l' support the meeting were not familiar with DisplayWrite. This meant that the U.S. team had to type and revise the Memorandum of Meeting from beginning to end. l l Interim Solution: As I learned more about the Soviet computer capability, I we began to transport some material (primarily lists of Soviet attendees and l documents) through the Soviet computers (via ASCII files) to the U.S. laptop. l l l

o 3 i Long Term Solution: We were fortunate that the Soviets had a computer I capability. However, this may not be the case for every meeting. Therefore, bringing a laptop to meetings in the USSR remains advisable. Further, having a . laptop permits work to be done offsite (e.g., in hotel rooms in the evening), and work to be done simultaneously on more than one machine. (There are usually three working groups producing draft text at the same time and there is a need to revise text at night in a hotel room for consideration the next day.) The Soviet's word processor has the advantage of accommodating both English and Russian text. Their processor is one of several having this dual capability. We are taking steps to assure that both countries have compatible word proces-sors which can produce text in both languages. This will permit draft texts of protocols and agendas to be negotiated between the two countries efficiently. 7. Problem: Host Country Payment: Without our knowledge, the Soviets had paid the hotel bill for the entire delegation. I discovered this the evening before our last night in Moscow. This action was contrary to the payment principle under which the JCCCNRS (with one specified exception) had operated to date. That is, the visitors pay their expenses. In view of the precedent-setting nature of the gesture, we insisted on paying the bill. However, since it had already been paid, the hotel would not accept our payment. Interim Solution: In view of our inability to pay the hotel directly, I presented the issue to my Soviet counterpart and a ranking official at the - Kurchatov Institute. As a result of some rather intense discussions and several consultations with other Soviets outside of our presence, we finally drew up a bill and receipt for the rooms with the Nuclear Society of the USSR as the party receiving payment. The evening before he left, the members of the U.S. delegation met to sign travellers' checks over to the Society in the amount of the room costs for all ten members (travellers' checks were the only acceptable means of payment; cash and personal checks were not acceptable). I presented the travellers' checks to the two Kurchatov officials. These two officials in turn presented us with the receipt listing the names of the ten U.S. delegates and the amounts paid by each. The receipt was signed by the Executive Secretary of the Society. Long-Term Solution: The Soviets did not explain why they paid the hotel bill. But it is clear that they are very anxious for the JCCCNRS to adopt a payment policy whereby the country hosting a delegation would pay the expenses of the delegation. That this is the case was made amply evident during a conversation I had with V. Asmolov, a member of the JCCCNRS (see below). Discussions with Others While the Working Group meetings were progressing, I had meetings with Vladimir Asmolov (of the Kurchatov Institute and JCCCNRS Committee member), Alexander Gutsalov (of the Nuclear Safety Supervisory Committee - GAEN and JCCCNRS member) and Alexei Davidov (of the Nuclear Supervisory Committee and member of the Soviet 1989 inspector exchange team). The following reports on the discussions I had with each. l l

4- .i Alexander Gutsalov and Alexei Davidov. GAEN: Three items of general interest emerged from our discussions. First, the Kurchatov Institute does not keep GAEN currently informed of JCCCNRS activi-ties. For example, it was only days before the December meeting that GAEN knew i of it. (We have asked Kurchatov to provide GAEN with copies of all correspon-3, dance we have with Kurchatov relating to the JCCCNRS. We also have formally r included the regulatory perspective in the meetings.) Second, no decisions have been made on the structure of GAEN as a result of the the overall reorganization of safety regulation that occurred in July 1988. L This has inhibited the agency from taking initiative. Gutsalov encouraged NRC to keep ideas flowing to GAEN to supply momentum to the Soviet regulatory process. Third, there is environmental legislation pending in the Supreme Soviet which likely will add an environmental component to GAEN's regulatory responsibili-ties. He asked for a compendium of environmental material which guides NRC decision-making. (A package including appropriate legislation and NUREGs is being prepared.) Vladimir Asmolov, Kurchatov Institute: Asmolov and I discussed two subjects of import. He raised the first subject, that of " host-country payment." He told'me that the expense of sending Soviets to the U.S. is so great that, without host-country payment, the USSR might have to terminate the exchange program as it is presently constituted. This conver-sation and the hotel incident (see above) do bring some immediacy to resolving the policy issue of host-country payment prior to the next meeting. I raised the second subject, which was to clarify the new organization of Soviet nuclear energy matters, in light of recent changes. He replied that organization of the upper echelons had been set, but that of the lower echelons were to be announced early in 1990. The organization of nuclear energy programs as Asmolov described them to me are as follows: l l

l .s-i r. t Current Organization of Soviet Nuclear Energy (Essentials) Fuel & Energy Complex Bureau - Ryabey i i (New) (Old) i; P!uclear Power' Medium Mach. ! i Industry & Operation p Bldg. Min. Ministry - Ryabey - Konovalov (constr NSSS) (inc1 fuel cycle) f Nuclear Power Min (design) Utilization of Atomic Energy i A. Protsenko 1 Kurchatov Atomic Energy Institute E. Velokov (Director) N. N. Ponomarev-Stepnoy (1st Deputy Director) Energy Ministry - Semenov (constr NPP; large buJget) Atomenergoproject Institute I - V. P. Tatarnikov, Chief Engineer (BOP design, like Bechtel) Hydropress Design Bureau - V. G. Federov Council of Ministers Emergency Situations - V. H. Dagudziev Safety Supervision of Industry & Atomic Energy V. Malyshev / I \\ Atomic Chemicals Manufacturing Mines Energy - Siderenko

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(; 6'- ~ Side Trip to Rovno NP.P.: s Af ter the substantive meetings concluded on Thursday, December 7. the delega-I tion flew by Aeroflot for two and one-half hours to the city of Rovno (capital of the Ukrainian Republic), thence by bus for three and one half hours to the Rovno nuclear power station. Accompanying the delegation to the station was a L. correspondent from the Tass News Agency. W At the nuclear power station,. we met with the plant director (Vladimir Korovkin), the mayor of the 33,000 population " company" town, and the chief engineer, among other officials (the names and titles of those with whom we met is enclosed). The plant manager has authority over all activities involving the town and plant. The mayor is responsible for all civic activities involv-ing the town, and the chief engineer is responsible for the daily activities L involving the plant. r Mr. Korovkin explained the history and management of the station. The designer of the plant was the Atomenergoprojekt in the Ministry of Energy. Construction began in 1971. Unit 1 (VVER 440) was completed at the end of 1980; Unit 2 (VVER 440) at the end of 1981; and Unit 3 (VVER 1000) at the end of 1986. A second VVER 1000 is under construction, due to be completed in 1992. Most noteworthy among Mr. Korovkin's remarks were that: "Most of the station staff are university graduates and received technical training at Novovoronesh. Technical relationships are maintained with the Byron plant in the U.S., and others in Finland, Czechoslovakia, Hungary and Spain. The " company" town has several subsidiary industries, including cattle breeding. There were several reasons why the station was located at this location, which is flat and remote: the soil is not fertile; the population was sparse; a local work force was available; and electricity could be supplied in several directions, including about 30% to Poland about 300 kilometers away. ~, There followed discussion of common mode failures, interlocks on the control room panels, the risk of criticality in spent fuel pools, and diesel generator reliability and battery capacity. The meeting was followed by a tour of small-scale models of the plant and by dinner. The next day included a tour of two units. The entire delegation toured the turbine hall and control room of Unit 3 (operating). Working Group 9 remained to discuss control room operations in more detail, while the rest of the delegation toured Unit 4 (under construction). (The delegation found Unit 4 far behind where it would be expected to be for a 1992 completion date.) In mid-afternoon, the delegation left for Moscow.

6 !l Enclosure j l I SOVIET ATTENDEES AT MEETING AT ROVNO NPP / [ I Korovkiri, Vladimir: Plant Director l Andreev, Evgeni: Chief Engineer Fedorochenko, Sergei: Deputy Chief Ergineer for Operations (Unit 3) Solovianov, 0!cg:' Deputy Chief Enginear for Operat'ons (Units 1 & ?) dansshchenko, Nikolai: Deputy Chief Engineer for N'iclear Safet) Andrieshin, Yaroslav: Chiti of the Training Center f Kulesha. Yuri: Assistant to the Plant Dire te.r e Malinov, V'ictorJ Chief $ppcialist, Npart. ment of Atomersotydprotect, Air,v K6zini.n Ant,toli: Inste11stion Orgknitation IJirector, Aovenskate.etech-energo Dzubenko, Harry: Group Le& der for Internations( Contacts Romanova, Olga: Interpreter Mazany, Victor: Tass Correspondent k .I 5}}