ML20140C399

Trip Rept of 970224-26 Visit to London,Uk Re 2nd Intl Conference on Fire & Safety Held in London,United Kingdom

ML20140C399
Person / Time
Issue date:	05/27/1997
From:	Larkins J NRC ADVISORY COMMITTEE ON NUCLEAR WASTE (ACNW), Advisory Committee on Reactor Safeguards
To:	Advisory Committee on Reactor Safeguards
References
NACNUCLE, NUDOCS 9706090237
Download: ML20140C399 (17)

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!' o NUCLEAR REGULATORY COMMISSION l 'C l! , ADVISORY COMMITTEE ON REACTOR SAFEGUARDS i WASHINGTON, D. C. 205S5

...../ May 27, 1997 l

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MEMORANDUM TO: ACRS Members FROM: John T. Larkins/

Executive Director, ACRS/ACNW

SUBJECT:

TRANSMITTAL OF FOREIGN TRIP REPORT OF ACRS STAFF ENGINEER Attached is a trip report by ACRS staff engineer Amarjit Singh on the 2nd International Conference on Fire and Safety held in London, United Kingdom, on February 24-26, 1997.

A copy of the transcript of this meeting is available in the ACRS/ACNW Office.

Attachment:

Trip Report by Amarjit Singh dated May 27, 1997, "2nd International Conference on Fire and Safety {

'97," London, United Kingdom, February 24-26, 1997 '

l cc: Chairman Jackson Commissioner Rogers Commissioner Dicus Commissioner Diaz Cc.,mmissioner McGaffigan L. J. Callan, OEDO S. J. Collins, NRR D. L. Morrison, RES D. F. Ross, OAEOD C. R. Stoiber, OIP

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TRIP REPORT 2ND INTERNATIONAL CONFERENCE ON FIRE & SAFETY '97 LONDON, UNITED KINGDOM FEBRUARY 24-26, 1997 AMARJIT SINGH MAY 1997 i l

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}- TRIP REPORT BY AMARJIT SINGH INTRODUCTION A 3-day conference was organized by Nuclear Engineering Interna- I tional/Wilmington Publishing to provide professionals from around

the world with a forum for in-depth exploration of fire safety for  !

l the nuclear power industry. Representatives from a number of the countries that have been involved in fire events at their respective nuclear facility (ies) were invited to present papers on these events. Their experiences differed, as did their views on I j how to communicate to the general public the fire protection  !

features associated with their countries about their nuclear power I plants to ensure that a fire is not allowed to create a public i relations nightmare for the nuclear power industry.

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! The following papers were delivered at the conference.

Fire Safetv--Current Activities at the International Atomic Enerav Acency-Kulig, Austria ]

This paper provided the background, objectives, and current activities conducted by the International Atomic Energy Agency (IAEA) in the area of fire safety. IAEA initiated a program on fire ' safety in 1993 which was intended to help member states to improve fire safety in nuclear power plants (NPPs).

The objective of the project was to (1) develop guidelines and good practices, (2) promote advanced fire safety assessment techniques, (3) exchange state-of-the art information between practitioners, and (4) provide engineering safety advisory services and training in the implementation of internationally accepted practices. This project was completed in 1996. As of the beginning of 1997, the fire safety-related activities .

were included in two new projects: (1) current engineering l safety issues, and (2) engineering safety advisory services. l The IAEA program on fire safety ensures the adequate fire safety of NPPs-both those under design and those in operation. Assistance is provided through the development of standards, guidelines, and good practice documents; the exchange of information; and the provision of advisory services and specialized training. The implementation of this program is well under way. The following significant tasks either have been accomplished or are in progress:

• Standard general fire safety requirements with regard to fire safety at operating plants have been developed.

Safety Practice documents, developed within the framework of the program, address all aspects of fire safety inspection, including hardware, organizational arrangements, and fire hazard analysis.

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l l - Trip Report Amarjit Singh The systematic collection and assessment of fire-related operational experience and the dissemination of essential insights from the assessment are currently in progress.

A topical symposium on upgrading the fire safety of operating plants that addresses all aspects of the safety upgrading process is scheduled to be held in October 1997. The symposium will include the exchange of experi-ence and lessons learned in fire safety assessment and backfitting of fire protection features.

IAEA assists in the systematic independent assessment of fire safety of NPPs in member states. The organization of fire safety review missions and training courses on I fire safety and fire protection at NPPs are continuing activities. Assistance is provided in solving plant-specific problems and also in building up the national I self-assessment expertise. I I

Manacement of Fire Safety in Indian Nuclear Installations-- l Balasubramanian, India l This paper presented many aspects of fire safety at nuclear installations in India. In the early days of the nuclear i power industry, attention given to fire protection aspects was l not of the same level of seriousness as was given to health physics or other nuclear-safety-related areas. Priority was given to the materials of construction from the combustion point of view. Every nuclear installation was governed by a dedicated fire brigade to handle fire fighting.

Following the Chernobyl accident, the Atomic Energy Regulatory Board (AERB) of India formed a Safety Review Committee (SRC) of operating plants to review fire safety at the NPPs. The SRC made several recommendations to upgrade the various aspects of fire safety at nuclear installations in India. One of the most important issues was to train the fire protection engineers. The SRC recommended the development of a compre-hensive training program which included the chemistry of fire, flame behavior, fire resistance of materials, flammable gases and liquids, fire-related building codes, fire risk evalu-ation, electrical aspects of fire, detection systems, concepts of fire zones, fire isolation, separation criteria of safety-related equipment, and the elements of fire hazard analysis.

Most of the recommendations have been implemented in individual unite.

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Amarjit Singh l Challences to Probabilistic-Based Fire Protection---Schmalz, U.S.A l This paper presented the challenges to the probabilistic-based assessments of fires. Probabilistic-based fire protection ,

l evaluates the risk from a fire in a designated room or area I by summing total risk from the numerous individual scenarios 1 that can be postulated to occur at the NPPs. Probabilistic- '

based fire protection has been a central topic of discussion  ;

in the fire protection community. The fire protection com- i munity is strongly attracted to the potential benefits of  !

quantifying risk using the probabilistic-based fire protection l assessment; however, one must not overlook its limitations and sensitivity to its modeling parameters. Coupled with the f act  !

'that fires constitute a major contribution to core damage I scenarios, the industry must exercise the utmost care in i applying probabilistic-based fire protection as the solution l to the most challenging issue, safe shutdown.

Key challenges, which, if not adequately addressed, may undermine the risk determined by the assessments. It is of ten hard to strike a balance between the attraction of analytical assessment and the reality of the real fire. As a fire pro-tection engineer, one must avoid total dependance on l probabilistic-based fire protection by challenging the adequacy and accuracy of the input parameters.

Acolication and Performance-Based Fire Protection in Reducina the Cost of Fire Protectio _n--Storey, U.S. A This paper discussed the opportunities for utilities to reduce i fire protection operations and maintenance (O&M) costs. Some of these opportunities can be implemented with additional 1 technical development in the area of fire protection. The  !

reason for moving to a performance-based process was that costs were out of control when results were considered (cost / benefit). Three unique factors suggest the basis for change to reduce cost in the NPP fire protection programs:

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1. NPP fire protection systems perform better and have less need for surveillance because training is better on their maintenance and use, and access to the areas containing them is tightly controlled. -

2. NPPs also have much lower fire hazards than the standard fire hazards established in the American Society for Testing and Materials (ASTM) Standard E-119 curve. With the fire modeling tools available today and the infor-mation obtained from the industry Individual Plant Exami-nation of External Events (IPEEE) program, these fire l

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Trip Report Amarjit Singh -l hazards can be sufficiently well estimated at reasonable cost.

3. Results of the IPEEE program indicate that fire-induced core-damage frequency is concentrated in only a few of

' the locations that contain nuclear safety equipment. The industry has developed techniques - and decision-making guidelines that use core-damage frequency estimates to substantially reduce regulatory requirements for. pump and valve testing. Those techniques similarly indicate that fire protection requiremento could also be substantially reduced. This is because the characteristics of the fire risk show patterns similar to the risk due to failure of pumps and valves.

These three unique perspectives provide a strong and comple-mentary basis for change that was not available when the currently applicable nuclear plant fire protection regulation and practices were promulgated in the early 1980s. Better-than-average equipment performance, lower-than-standard fire hazards, and public health risks concentrated in a few loca-tions, all individually and collectively indicate the avail-1 ability of a substantial technical basis for reducing O&M costs.

A performance-based approach to fire protection can provide unique insights that augment deterministic approaches. It can tell us when suppression capability is important and how long barriers need to function. Finally, a performance-based approach to fire protection can sllow us to establish an effective fire protection program that can be implemented at a lower cost without any deleterious impact on safety.

DeveloDaent of Criteria for the Fire Safety Assessment of German Nuclear Power Plants Under Operation--R6wekamp, Germany This paper presented the background and the development of the criteria for the fire safety assessment of the existing operating NPPs in Germany. The existing guidelines and

- standards for the design of new NPPs are not always applicable for the assessment of fire protection measures in older plants. i There are 20 nuclear units operating in Germany. The oldest of these plants was designed and constructed in the mid-1960s.

With respect to fire protection in NPPs, it is crucial for plant safety that not all of the required safety systems fail in case of an internal fire at the plant. The plant safety determined the fire protection concept for the German NPPs in a way that physical fire protection, mainly by structural protection measures, was given priority over other measures I

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l l Trip Report l Amarjit Singh for protection of redundant safety-related equipment. It is interesting to note that three separate standards have been I applied. The first generation plants were built with mainly spatial separation of redundant safety-related equipment l instead of separation by structural protection measures and by l providing manual fire fighting capabilities. The second generation plants were designed and constructed by physical separation (e.g., fire walls and barriers with differing fire resistance ratings), including the manual fire fighting capabilities. The third generation plants were constructed with mainly physical separation of redundant safety-related j equipment by structural protection measures with a fire resistance rating of 90 minutes. Manual fire fighting l capabilities were not required. The first German NPP-specific l fire protection standard came into effect in 1986; this l standard was applicable to the third generation plants. I 1

Experience From German Reliability Data for Fire Protection j Measures in NPPs With Recard to Probabilistic Fire Safety i Analyses-Berg, Germany  !

l The NPPs in Germany are designed and built in accordance with l earlier standards which varied from year to year, especially l in the area of fire protection. The probabilistic safety l studies, including fire risk studies, are already used for  ;

case-by-case decisions by the utilities and the regulatory authorities. The actual reliability data for the technical l failures of the active fire protection feature can be used for I these kinds of probabilistic fire risk studies as input data for the event-tree analyses. It has to be pointed out as a general conclusion that the required data base to perform probabilistic safety analysis in Germany has to be expanded and improved by using the plant-specific data.

Systematic Approach for a Probabilistic Fire Analysis-Zander, Germany This paper described a basic approach for assessing the contribution of internal fires to core damage frequency at power and non-power conditions. This approach (combining the different methods established for full-power operation and transferring it to non-power operation modes), will lead to more realistic plant-specific results.

Experience Feedback Systems Concerninc Fire Protection and Prevention in Nuclear Facilities-Havel, Sweden l This paper emphasized the approach of the data base collection

! and the experience feedback concerning fire protection and prevention. Fires occur every year at a number of NPPs over the world. Some of these fires could have been avoided if

Trip Report Amarjit Singh experience from other similar events had been used. Fires are potential initiators to severe transients in NPPs, and the costs for restoration and power production losses are high.

It is thus important to minimize the risks of fire events in a nuclear facility. It was emphasized in this paper that a worldwide database for fire events at NPPs would be a big step in fire prevention.

Fire Events-Feedback of U.S. ODeratina Experience--Houghton, U.S.A.

This paper characterized the frequency and nature of updated fire-event data from United States operating plants and  ;

determined the potential impact this data could have on fire risk assessments for U.S. NPPs. This paper provided a review ,

and revision to the existing fire events database (for events '

from 1965 through 1985). This fire event database was l collected from licensee event reports (LERs), component failure histories from the Nuclear Plant Reliability Data System (NPRDS), and the Electric Power Research Institute I (EPRI) database.

The updated data for 1965-1994 included the following fire i events: (1) apportionment of fire events by number, (2) major cause and plant location, (3) evaluation of the duration and ,

frequency of fire events that occurred during power and I shutdown operations, (4) comparison of the updated power operations fire frequency with probabilistic risk assessment (PRA) data, (5) recent industry- and NRC-sponsored studies for effect on fire-induced core damage frequency estimates, and (6) comparison of the duration and frequency of shutdown fire events with power operations fire events. l l

It was concluded in this paper that operating experience  ;

indicates that the frequency and duration of fire events I during shutdown operations appear to be less significant than i those events occurring at power operation. l Ontario Hydro Perspective-McCulloch, Canada This paper provided the background of the 20 CANDU nuclear reactors, pressurized heavy water reactors (PHWR), owned and operated by Ontario Hydro at three major sites in Ontario.

Each of Ontario Hydro's CANDU plants is a multi-unit design comprising four reactors, a central or co:1. mon services area, and a common turbine hall housing four turbines. Each reactor vault is connected to a large, evacuated structure by either an aboveground or underground duct (pressure relief duct).

The use of fixed fire protection systems is limited to the immediate vicinity of each turbine, new fuel storage areas, and general storage areas in the plant or areas in which there

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is a substantial fire hazard such as standby power generator rooms. With the exception of the area around the. turbine 1 pedestal.and some of the lower elevations, the turbine hall has no sprinkler system. Fire protection features are provided based on the significance of the hazards. The key .

I features of fire protection in a CANDU multi-unit plant are as follows:

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• A' fixed fire protection system in a specific plant area is based on the assessment of risk. (This requires an evaluation of the risk by deterministic or probabilistic i l- methods or some combination of the two such as the Fire Induced Vulnerability Evaluation (FIVE) methodology.

Such assessments allow plant managers to prioritize fire protection resources to deal with the highest risk first.]

• .The minimization of combustible materials at the design-stage. j Control and minimization of transient combustible materials.

Control of ignition sources by work permit.

• Establishment of a strong emergency response to fires.

The control rooms and control equipment rooms are within the central structure and contain the operational controls, data-gathering equipment, and digital-control computers for all four reactors of a multi-unit plant and are not protected by fixed fire protection systems and also not separated by fire walls or barriers. It is interesting to note that Ontario Hydro's perspective on fire protection is based on the five key concepts which are stated above. I Report From China-Hong, China This paper gave an overview of the fire protection strategy and experience at the Guangdong Daya Bay Nuclear Power Station (GNPS). The GNPS was built under a joint venture partnership between Guangdong Province of China and China Light & Power Ltd., Hong Kong. The plant was designed in accordance.with European standards. Standards and codes from three countries were used in the GNPS design: (1) . French Criteria, RCC-1,

" Rules for Fire Protection in PWR . Nuclear Power Plants,"

Revision B, were used for the nuclear island; (2) British criteria were used for the conventional island, and (3) l Chinese standards were used for non-safety-related areas. The

documents, " International Guidelines for Fire Protection of l Nuclear Power Plants," 1983 Edition, published by the

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Trip Report Amarjit Singh Worldwide Nuclear Insurance Property Pools, was' used as a l reference. The GNPS began commercial operation on February 1, 1 1994. l The GNPS is equipped with fire protection features such as a

! fire detection system, an ignition source control, fire '

! barrier penetration seals, a quality assurance program, a fire l l protection water supply system, and a fixed fire-suppression I system. The responsibility for fire protection at the plant is delegated _to the Industrial Safety Section within the Health Physics Branch; it is staffed with certified fire protection engineers and technicians. The management at GNPS I l also monitors the worldwide fire protection experience and I practice in order to maintain state-of-the-art technology and make appropriate modifications at GNPS.

Duke Power ComDany Fire ProtectioL Procram-Brandes , U.S.A This paper described the growth and continuing improvement of

! the Duke Power Company's fire protection program. The l discussion of this paper is based on the current practices at l Duke Power Company's facilities. Fire safety is a very important element of the overall safety and productivity of a

commercial nuclear power generating station. The fundamental

requirements of an optimum fire safety program include elements of' defense-in-depth, regulatory compliance, issues beyond regulation which are important for the protection of personnel, the capital investment in the facility, and the l unit availability. The management support for fire safety is one element in the overall insistence on safety-both nuclear, industrial, and personnel. Responsible management must not be I wavering and must never be compromised for conveniences or L priorities such as continued production or lack of funding.

The U.S. nuclear industry must answer to the public for ensuring nuclear safety. To fulfill this responsibility, the l industry has adopted the philosophy of " defense-in-depth" for fire safety at commercial nuclear generating units. In j summary, the fire safety program at a commercial nuclear power >

plant is a comprehensive program which affects all areas of l

design arrangement, operation, maintenance, and related activities. It must be implemented in a comprehensive' manner and must be considered in every element of day-to-day activity.

l Halon Reduction: The Rinchals Procramme--Magnusson, Sweden f This paper described the reduction plan of Halon 1301 in i Sweden. In 1987, the Swedish authorities signed the Montreal

Agreement for Halon reduction. The Swedish authorities have banned the use of Halon 1301 for the new installations, I

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Trip Report Amarjit Singh effective January 1, 1991. Effective January 1, 1998, all the existing Halon systems have to be replaced with other fire extinguishing systems. The production of Halon 1301 has been banned since 1994. Since 1994, in accordance with the Swedish regulations, all users of Halon 1301 have to report their volume of Halen 1301 to the local county board.

The Narora Fire and its Continp_ina Consecuences: 'Backfittin_g the Indian PHWRS-Bohra, India This paper described the fire at the Narora Atomic Power Station (NAPS) in India, consequent retrofitting of recent fire standards in Indian pressurized, heavy-water reactors 3

(PHWRs), and major considerations in retrofitting such as active and passive fire protection, control room habitability ,

and fire management. Narora Atomic Power Station is a twin unit, 220 MWe PHWR. On March 31, 1993, Unit 1 was operating l and Unit 2 was in the shutdown state (the primary heat transport (PHT) system was in a cold and pressurized state).

At approximately 3:30 a.m. a huge fire was seen under the turbine generator and the reactor wta tripped manually. Fire 3

spread from the mezzanine floor of the turbine building into i the control equipment room along the cable trays, breaching the cable penetration barrier. Large amounts of smoke entered

the control room through the control equipment room and air i supply diffuses, which forced the staff to evacuate the control room. There was a complete loss of the power supply.

Subsequent investigations revealed that the root cause of the l fire was the fatigue failure of last-stage blades of the low-pressure turbine, which resulted in massive imbalance causing the failure of turbine bearing and hydrogen seals. Hydrogen leaked through the seals at the slip-ring end and caught fire from the sparks at the slip rings. Oil pipes connected to the turbine-generator snapped from excessive vibration and impact; l leaked oil from the pipes sustained the fire. The fire spread to cables, which led to station blackout. The main fire was completely extinguished in one and a half hours.

In the old NPPs, the fire protection measures were limited to safeguarding against major fire risks in transformers, oil tanks, oil storage, pumps, cable tunnel ends, cable ducts, etc., and were not so strongly focused on reactor safety in relation to all possible fire scenarios. The lack of defense-in-depth approach in fire safety design in the older plants is a common problem in the area of fire protection. The most important reason for all major fire incidents in the older NPPs is lack of built-in defense mechanisms against fire for containing fire and also for preventing common cause failure of redundant safety trains.

0 Trip Report Amarjit Singh The Narora fire has led the Indian Atomic Energy Board to urgently review the existing fire safety measures in all Indian NPPs. Since the Narora fire, Narora Units 1 and 2 and Kakrapara Units 1 and 2 have been backfitted with upgraded fire protection features, including a defense-in-depth approach. The remaining units are undergoing various stages of backfitting of fire protection features.

Fire Protection UDaradina in French "Licuid Metal Fast Reactors"--Tournebise, France This paper described the fire protection upgrades and characteristics of the liquid metal fast reactors. Sodium is used as a cooling fluid in these reactors. Sodium is highly flammable at the temperature encountered in normal operation.

It is spontaneously flammable with dry air temperature of 200 *C. During normal operation, the temperature outside the core varies between 350 and 550*C.

The following three types of sodium fires need to be considered:

o Pool fire, with short flames and a lot of white fumes.

It occurs when hot sodium is flowing simply and burning in a puddle of liquid rodium. The thermodynamic behavior is slow and easy to control.

• Spray fire, when the sodium is divided into thin droplets. The thermodynamic behavior is very brisk with a quick and huge pressure shock and an increase of the temperature (not at the same time).

e Mixed fire, in which there is a combination of pool and spray fires.

Sodium also reacts violently when it contacts water. Thermal  !

consequences on concrete can lead to water desorption out of l it and can potentially produce hydrogen.

The initial prevention from sodium fire is based on leak tightness of piping. Since the sodium fire which destroyed a sodium-cooled solar plant in Almeria (Spain), very extensive improvements and engineering work has been performed in France, including the enhancement of research and development in the area of sodium fires.

In France, assessment of fire risks for future liquid metal I fast reactors is ongoing in the European Fast Reactor (EFR) ,

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Trip Report Amarjit Singh Palo Verde Nuclear Generatina Stations Unit 2 Fire Event on

( April 4. 199 6 --Summary and Corrective Actions-Kleinsorg, U.S.A.

This paper described the fire event at Palo Verde Unit 2 and the corrective actions taken by the licensee. On April 4, 1996, when Unit 2 was in Mode 6 with one fuel assembly in the reactor vessel, an ALERT was declared at Palo Verde Unit 2, because of two related fires in a back panel of the main control room. The.se fires were associated with voltage regulator transformers which provide 120-VAC to non-safety-related uninterruptible power supply. These fires affected one train of essential and emergency lighting in the control room. Licensee personnel extinguished the fires using portable CO2 equipment. The ALERT was declared because of the potential impact of these fires on safety-related equipment.

The root cause of the fire was attributed to an electrical grounding design problem. Following the event, a special inspection was conducted by NRC Region IV staff at Palo Verde Unit 2.

The following actions were taken to correct the existing condition of the electrical grounding: (1) relocate the ground connections at the converter, (2) add a solid ground to the neutral leg at the regulating transformer, (3) add a fuse at the hot-leg output of the regulating transformer. In this manner, future ground fault current will be limited to the immediate vicinity of the regulating transformer. The fuse will provide - protection for the cable from the regulating transformer to the lighting panel. Similar modifications were required for other regulating transformer installations that were found to have the same design problem.

Deratino of Cables at Hich Temperatures-Keski-Rahkonen, Finland This paper discussed the study on the behavior and derating of cables at high temperatures in NPPs. This study collected the data for fire risk analysis to estimate how long a cable or an electric instrument performs its intended function at elevated temperatures caused by a fire. A method was developed to characterize the behavior of cables used in NPPs at tempera-tures exceeding the long-term rating. The problem is to predict how long and at what temperature cables will continue to function under emergency situations. Cable manufacturers i use three different temperature regions when rating cables:

l (1) normal maximum operation temperature, (2) maximum emer-l gency operation temperature, and (3) short-circuit tempera-

! ture. In this study, polyvinyl chloride (PVC) cable insula-tion was used.

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Amarjit Singh This study indicated that the PVC cable functioned properly under the normal operating conditions up to 196*C. There was no indication of continuous insulation derating at the elevated temperature. In conclusion, the rating of electrical performance of cables at high temperature can be simplified to measurements of conductivity of cable insulation material where the Arrhenius-type (Arrhenius preexponential factor, area) of temperature behavior is not followed strictly, but is useful for guidance.

Unaradina Fire Safety at Soviet-Desianed Reactors-Ramsey, U.S.A.

This paper discussed the program supported by the U.S.

Department of Energy (USDOE) to upgrade the fire safety of the Soviet-designed reactors in Russia, Ukraine, and in central East Europe.

There are two major types of Soviet-designed reactors. The RBMK is the Chernobyl type of reactor-a graphite-moderated, boiling-water reactor. Ten reactors of this type are currently operating in Russia, two in Ukraine, and two in Lithuania. The two Lithuanian reactors are 1500-megawatt electric plants and others are 1000-megawatt electric plants.

The second type of the reactor is the VVER. It is a pressurized-water reactor that is conceptually similar to western-designed pressurized reactors. There are three major variations in VVER design: an older 440-megawatt electric design (model 230), the more recent 440-megawatt electric design (model 213), and the 1000-megawatt electric design.

There are many plants of these types operating in Russia, the Ukraine, and central Eastern European countries.

Both major types of Soviet-designed reactors have fire vulner-abilities in their design. The older designs tend to have more severe problems than the more recent designs. RBMK l safety issues were reviewed very thoroughly by an i international consortium of 170 specialists from 11 countries.

The fire safety review was led by representatives from Finland and Russia. Many problems were identified and recommendations were made for upgrades. Fire safety issues have also been identified by a number of other independent reviews of VVER l and RBMK plants, particularly under the direction of the International Atomic Energy Agency (IAEA). Some of the sig-nificant fire safety vulnerabilities in these designs are as follows:

• Although safety components may be provided with redun-dancy, they are subject to common-cause failure because redundancy is not carried throughout the system design.

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e Trip Report Amarjit Singh The plant layout is not generally designed with the aim of localizing fires. Key instrumentation, safety systems, and especially the control room are extremely vulnerable to fire damage. Fire confinement in very large rooms (e.g., the turbine hall) is nonexistent.

Use of advanced technology in the development of noncom-bustible/ limited combustible materials, especially for roofing, floor covering, and cable coatings, is generally lacking.

In addition, poor fire safety is often practiced during the operation of these plants. Personnel are allowed to smoke inside the plant, good housekeeping may not be enforced, and large amounts of combustible materials can accumulate.

The fire safety projects supported by USDOE are to reduce the risk that a fire could cause in the loss of a critical safety function, in damage to the reactor core, and in release of radioactive material from the plant. The approach taken in the USDOE-supported fire safety is highly influenced by an underlying philosophy of the Soviet-designed reactor safety program by the respective host country. The benefit in risk reduction will only be temporary unless the capability to maintain equipment, replace components, and extend the safety improvements to other plants is transferred with the equip-ment Furthermore, a comparable level of safety upgrades cannot be provided for all plants with U.S. funding. Thus, the fire safety projects emphasize training, support of host country suppliers when practical, and the upgrade of host country standards.

The USDOE's program to assist in improving fire safety at Soviet-designed reactors is focused on reduction of a fire leading to core damage and the release of radioactive material. The program is based on the defense-in-depth approach of fire prevention, detection and suppression, and assuring safe-shutdown capability.

• Fire Prevention The USDOE program to improve fire safety at Soviet-designed reactors primarily addresses fire prevention through training. (This is also an area in which the U.S.

NRC has provided substantial assistance to plant personnel and regulatory staff in host countries.) The i

guidelines being developed in this program to ensure safe-shutdown capability begin with an assessment of the fire. prevention practices at the plant.

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Trip Report Amarjit Singh e Fire Detection and Suppression The U.S. is providing fire detection and suppression equipment to the Smolensk and Leningrad NPPs in Russia; the Chernobyl and Zaporizhya NPPs in Ukraine and Armenia; and previously provided equipment to the Kozloduy NPP in Bulgaria. Much of the equipment offers very basic protection to fire fighters, such as fire suits, air breathing apparatus, manual fire fighting equipment, and variable spray hose nozzles. The Soviet-designed plants typically do not have the extent of automated fire suppression systems as are in the U.S. They do, however, have large, well-trained fire brigades.

e Assuring safe Shutdown capability Representatives of USDOE and USNRC, and the nuclear industry, have developed guidelines for performing safe-shutdown analysis. The Russian organization VNIIAES has been assigned responsibility for modifying these guidelines into a form that can be adopted as a Russian standard for safe shutdown analysis. A similar effort is planned in Ukraine. The guidelines provide an approach for performing safe shutdown analyses to identify cost-effective plant upgrades for Soviet-designed plants.

Although much of the support is in the form of equipment and materials, it is recognized that technology transfer is essential to assuring that the upgrades being provided will be sustained by most host countries and extended to other NPPs. There-is consensus among experts about the importance of improving fire protection at these plants.

The challenge for the USDOE program is to provide upgrades that have the greatest risk significance, and to provide mechanisms for the host countries to be self-sufficient in maintaining an acceptably small level of risk.

CONCLUDING REMARKS The primary message delivered by those presenting papers on rine various aspects of fire safety is that exchanging information and sharing the lessons learned from the fire events that occur at the respective plants benefits all.

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