ML14175A729

Exemption Granting Addl Time to Complete Reassessment of Fire Protection Features as Required by 10CFR50,App R

ML14175A729
Person / Time
Site:	Robinson
Issue date:	05/10/1982
From:	Harold Denton Office of Nuclear Reactor Regulation
To:	Carolina Power & Light Co
Shared Package
ML14175A730	List: ML14175A729
References
NUDOCS 8205270492
Download: ML14175A729 (23)

Text

• CLEAR REGULATORY COMMISSION In the Matter of

)

CAROLINA POWER AND LIGHT

)

Docket No. 50-261 COMPANY

)

(H. B. Robinson Unit

)

No. 2)

)

EXEMPTION I.

The Carolina Power and Light Company (the licensee) is the holder of Facility Operating License No. DPR-23 which authorizes operation of the H. B. Robinson Plant, Unit No. 2. This license provides, among other things, that it is subject to all rules, regulations and Orders of the Commission now or hereafter in effect.

The facility comprises one pressurized water reactor at the licensee's site located in Darlington County, SouthCarolina.

II.

On November 19, 1980, the Commission published a revised Section 10 CFR 50.48 and a new Appendix R to 10 CFR 5O regarding fire protection features of nuclear power plants (45 F.R. 76602). The revised Section 50.48 and Appendix R became effective on February 17, 1981.

Section 50.48(c) established the schedules for satisfying the provisions of Appendix R.Section III of Appendix R contains fifteen subsections, lettered A through 0, each of which specifies requirements for a particular aspect of the fire protection features at a nuclear power plant. Two of these fifteen subsections III.G and III.L are the subject of this exemption request. III.G specified (I

detailed requirements for fire protection of the equipment used for safe shutdown by means of separation and barriers (III.G.2).

If the requirements for separation and barriers could not be met in an area, alternative safe shutdown capability, independent of that area and equipment is that area, was required (III.G.3) and III.L.*

DESIGNATED 0 IGI1AL 00

• Note III.L provides the criteria for III.G.3.

Captified By______

-2 Section 50.48(c) required completion of all modifications to meet the provisions of Appendix R within a specified time from the effective date of this fire protection rule, February 17, 1981, except for modifications to provide alternative safe shutdown capability. These latter modifications (III.G.3 and III.L) require NRC review and approval.

Hence, Section 50.48(c) requires their completion within a certain time after NRC approval.

The date for submittal of design descriptions of any modifications to provide alternative safe shutdown capability was specified as March 19, 1981.

By letter dated March 11, 1981, as amended June 30, 1981, October 15, 1981 and March 1, 1982, Carolina Power and Light requested exemptions from 10 CFR 50.48(c) with respect to the requirements of Section III.G and III.L of Appendix R as follows:

(1) Extend from March 19, 1981, to March 10, 1982, the date for submittal of plans and schedules to achieve compliance with III.G.2 required by

§50.48(c)(5);

(2) Extend from March 19, 1981 to March 10, 1982, the date for filing additional exemptions from Section III.G and III.L pursuant to

§50.12(a) and 50.48(c)(6);

(3) Extend from March 19, 1981, to March 10, 1982, the date for submittal of design descriptions of alternative or dedicated shutdown systems to comply with Section III.G.3 and III.L if such are necessary; and (4) Extend from February 17, 1981, to March 10, 1982, the date from which the installation schedules established in §50.48(c)(2) and (3) are calculated.

When this Fire Protection Rule was approved by the Commission, it was understood that the time required for each licensee to re-examine those previously-approved configurations at its plant to determine whether they meet the requirements of Section III.G of Appendix R to 10 CFR 50 was not well known and would vary depending upon the degree of conformance. For

-3 each item of non-conformance that was found, a fire hazards analysis had to be performed to determine whether the existing configuration provided sufficient fire protection. If it did, a basis had to be formulated for an exemption request. If it did not, modifications to either meet the requirements of Appendix R or to provide some other acceptable configuration, that could be justified for an exemption, had to be designed. Where fire protection features alone could not ensure protection of safe shutdown capability, alternative safe shutdown capability had to be designed as required by Section III.G.3 and III.L of Appendix R. Depending upon the extensiveness and number of the areas involved, the time required for this re-examination, reanalysis and redesign could vary from a few months to a year or more. The Commission decided, however, to require one, short-term date for all licensees in the interest of ensuring a best-effort, expedited completion of compliance with the Fire Protection Rule, recognizing that there would be a number of licensees who could not meet these time restraints but who could then request appropriate relief through the exemption process. Licensees for 44 of the 72 plants to which Appendix R applies (plants with an operating license issued prior to January 1, 1979) have requested such schedular relief.

The licensees for the remaining 28 plants made submittals to meet the schedular requirements of 50.48(c). All of these submittals, however, were deficient in some respects. In general, much of the information requested in a generic letter (81-12) dated February 20, 1981, to the licensees of all 72 plants, was not provided. Therefore, additionr7 time is being used to complete those submittals also.

-4 III.

Prior to the issuance of Appendix R, H. B. Robinson Unit 2 had been reviewed against the criteria of Appendix A to the Branch Technical Position 9.5-1 (BTP 9.5-1). The BTP 9.5-1 was developed to resolve the lessons learned from the fire at Browns Ferry Nuclear Plant. It is broader in scope than Appendix R, formed the nucleus of the criteria developed further in Appendix R and in its present, revised form constitutes the section of the Standard Review Plan used for the review of applications for construction permits and operating licenses of new plants. The review was completed by the NRC staff and its fire protection consultants and a Fire Protection Safety Evaluation (FPSER) was issued.

A few items remained unresolved. Further discourse between the licensee and the NRC staff resulted in resolution of these items as documented in two supplements to the FPSER. The FPSER and its supplements supported the issuance of amendments to the operating licenses of H. B. Robinson Unit 111 which required modifications to be made to plant physical features, systems, and administrative controls to meet the criteria of Appendix A to BTP 9.5-1.

All of these modifications have been completed. Therefore, the H. B. Robinson Unit 1 has been upgraded to a high degree of fire protection already and the extensive reassessment involved in this request for additional time is to quantify, in detail, the differences between what was recently approved and the specific requirements of Section III.G to Appendix R of 10 CFR 50.

1/ H. B. Robinson Unit 2 - Operating License DPR-23 Amendment 31 supported by FPSER issued February 28, 1978 Supplement 1 to FPSER issued February 21, 1980 Supplement 2 to FPSER issued December 8, 1980

-5 Based on the above considerations, we find that the licensee has completed a substantial part of the fire protection features at H. B. Robinson Unit 2 in conformance with the requirements of the Fire Protection Rule and is applying significant effort to complete the reassessment of any remaining modifications which might be necessary for strict conformance with Section III.G. We find that because of the already-completed upgrading of these facilities, there is no undue risk to the health and safety of the public involved with continued operation until the completion of this reassessment on June 30, 1982. Therefore, an exemption should be granted to allow such time for completion. However, because we have found that most submittals of this reanalysis to date from other licensees have not been complete; that is, not all of the information requested by Generic Letter 81-12 dated February 20, 1981, was provided, we are adding a condition to this exemption that requires all such information to be submitted by the date granted.

IV.

Accordingly, the Commission has determined that, pursuant to 10 CFR 50.12; an exemption is authorized by law and will not endanger life or property or the common defense and security and is otherwise in the public interest and hereby grants the following exemptions with respect to the requirements of Section III.G of Appendix R to 10 CFR 50:

(1) The date, March 19, 1981, for submittal of plants and schedules to achieve compliance as required by §50.48(c)(5) is extended to March 10, 1982; (2) The date, March 19, 1981 for filing exemption requests pursuant to

§50.48(c)(6) which includes a tolling provision is extended to March 10, 1982; (3) The date, March 19, 1981, for submittal of design descriptions of alternative or dedicated shutdown systems to comply with Section III.G.3 and III.L as required by §50.48(c)(5) is extended to March 10, 1982; (4) The date, February 17, 1981, from which the installation schedules established in 950.48(c)(2) and (3) are calculated, is extended to March 10, 1982;

-6 Provided the following conditions are met:

(1) Requests for exemption pursuant to §50.48(c)(6) must include:

(a) A concise statement of the extent of the exemption; (b) A concise description of the proposed alternative design features related to assuring post-fire shutdown capability; and (c) A sound technical basis that justifies the proposed alternative in terms of protection afforded to post-fire shutdown capability, degree of enhancement in fire safety by full compliance with III.G requirements, or the detriment to plant safety incurred by full compliance with III.G and III.L. A simple statement that the feature for which the exemption is requested was previously approved by the staff is not sufficient. A simple assertion that in the licensee's judgment the feature for which the exemption is requested is adequate fire protection is not sufficient.

(2) The design descriptions of alternative or dedicated shutdown systems to comply with Section III.G.3 and III.L, as required by §50.48(c)(5) shall include a point-by-point response to each item in Section B of Enclosure 1 to generic letter 81-12 dated February 20, 1981, and to each item in to Generic Letter 81-12, dated February 20, 1981.

If the licensee does not meet the above conditions, the licensee will be found in violation of 10 CFR 50.48(c) even though the submittal may be made within the time limit granted by the exemption. If such a vi6lation occurs, imposition of a civil penalty will be considered under Section 234 of the Atomic Energy Act, as amended. Such a violation will be a continuing one beginning with the date set in the exemption for submittal and terminating when all inadequacies are corrected.

A delay in the determination of inadequacy by the staff, caused by the work load associated with reviewing all of the submittals falling due near the same time, will not relieve the licensee of the responsibility for completeness of the submittal, nor will such delay cause any penalty that may be imposed to be mitigated.

-7 The NRC staff has determined that the granting of this exemption will not result in any significant environmental impact and that pursuant to 10 CFR 51.5(d)(4) an environmental impact statement or negative declaration and environ mental impact appraisal need not be prepared in connection with this action.

FOR THE NUCLEAR REGULATORY COMMISSION Harold R. Denton, Director Office of Nuclear Reactor Regulation Dated at Bethesda, Maryland this 10th day of May 1982

.LNLLUSURE Z SAFE SHUTDOWN CAPABILITY The following discusses the requirements for-protecting redundant and/or alternative equipment needed for safe shutdown in the event of a fire. The requirements of Appendix R address hot shutdown equipment which must be free of fire damage. The follOwing..reqvirements also apply to cold shutdown equipment i-f the. licensee elects to demonstrate that the-equipment. Is to-be free of.fire.damage. Appendix R does allow.repairable damage to cold shutdown equtoment.

Using the requirements of Sections III.G and III.L of Appendix R, the capa bility to achieve hot shutdown must exist given a fire in any area of the plant in conjunction with a loss of offsite power for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.Section III.G of Appendix R provides four methods for ensuring that the hot shutdown capa bility is protected from fires. The first three options as defined in Section III.G.2 provides methods for protection-from fires of equipment needed for hot sbutdown:

1. Redundant systems including cables, equipment, and associated circuits may be separated by a three-hour fire rated barrier; or,

2. Redundant systems including cables, equipment and associated circuits may be separated by a horizontal distance of more than 20 feet with no inter vening combustibles. In addition, fire detection and an automatic fire suppression system are required; or,

3. Redundant systems including cables, equipment and associated circuits may by enclosed by a one-hour fire rated barrier. In addition, fire detectors and an automatic fire suppression system are required.

-2 The last option as defined by Section III.G.3 provides an alternative shutdown capability to the redundant trains damaged by a fire.

4. Alternative shutdown equipment must be independent of the cables, equip ment and associated circuits of the redundant systems damaged by the fire.

Associated Circuits of Concern The following discussion provides A) a definition of associated circuits for Appendix R consideration, B) the guidelines for protecting the safe'shutdown capability from the fire-induced failures of associated circuits and C) the in formation required by the staff to review associated circuits. The definition of associated circuits has not changed from the February 20, 1981 generic letter; but is merely clarified. It is important to note that our interest is only with those circuit (cables) whose fire-induced failure could effect shutdown.

The guidelines for protecting the safe shutdown capability from the fire-induced failures of associated circuits are not requirements. These guidelines should be used only as guidance when needed. These guidelines do not limit the alter natives available to the licensee for protecting the shutdown capability.

All proposed methods for protection of the shutdown capability from fire-induced failures will be evaluated by the staff for acceptability.

A. Our concern is that circuits within the fire area will receive fire damage which can affect shutdown capability and thereby prevent post-fire safe shutdown. Associated Circuits* of Concern are defined as those cables (safety related, non-safety related,Class lE, and non-Class 1E) that:

• The definition for associated circuits is not exactly the same as the definition presented in IEEE-384-1977.

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1. Have a physical separation less than that required by Section III.G.2 of Appendix R,.and;

2. Have one of the following:

a. a common power source with the shutdown equipment (redundant or alternative) and the power source is not electrically protected from the circuit of concerp by coordinated breakers, fuses, or similar devices (see diagram 2a), or

b. a connection to circuits of equipment whose spurious operation would adversely affect the shutdown capability (e.g., RHR/RCS isolation valves, ADS valves, PORVs, steam generator atmospheric dump valves, instrumentation, steam bypass, etc.) (see diagram 2b), or

c. a common enclosure (e.g., raceway, panel, junction) with the shutdown cables (redundant and alternative) and, (1) are not electrically protected by circuit breakers, fuses or simi lar devices, or (2) will allow propagation of the fire into the common enclosure, (see diagram 2c).

EXAMPLES OF ASSOCIATED CIRCUITS OF CONCERN

. ir E VREA Ff Elo oilH 8

ss BoThe area barriers shown above meet the appropriate sub-paragraphs (a-f) optr i codel a ofedJ of section III.G-2 of Appendix R.

Diagram 2A Diagram 2B Diagram 2C

-4 B. The following guidelines are for protecting the shutdown capability from fire-induced failures of circuits (cables) in the fire area.

The guidance provided below for interrupting devices applies only to new devices installed to provide electrical isolation of associated circuits of concern, or as part of the alternative or dedicated shutdown system.

The shutdown capability may be protected from the adverse effect of damage to associated circuits of concern by the following methods:

1. Provide protection between the associated circuits of concern and the shutdown circuits as per Section III.G.2 of Appendix R, or

2. a. For a common power source case of associated circuit:

Provide load fuse/breaker (interrupting devices) to feeder fuse/breaker coordination to prevent loss of the redundant or alternative shutdown power source.

To ensure that the following coordination criteria are met the following should apply:

(1)

The associated circuit of concern interrupting devices (breakers or fuses) time-overcurrent trip characteristic for all circuits faults should cause the interrupting device to interrupt the fault current prior to initiation of a trip of any upstream interrupting device which will cause a loss of the common power source, (2) The power source shall supply the necessary fault current for sufficient time to ensure the proper coordination without loss of function of the shutdown loads.

-5 The acceptability of a particular interrupting device is considered demonstrated if the following criteria are met:

(i) The interrupting device design shall be factory tested to verify overcurrent protection as designed in accordance with the applicable UL, ANSI, or NEMA standards.

(ii) For low and medium voltage switchgear (480 V and above) circuit breaker/protective relay periodic testing shall demonstrate that the overall coordination scheme remains within the limits specified in the design criteria. This testing may be performed as a series of overlapping tests.

(iii)

Molded case circuit breakers shall peridically be manually exercised and inspected to insure ease of operation. On a rotating refueling outage basis a sample of these breakers shall be tested to determine that breaker drift is within that allowed by the detign criteria. Breakersshould be tested in accordance with an accepted QC testing methodology such as MIL STD 10 5 D.

(iv)

Fuses when used as interrupting devices.do not require periodic testing, due to their stability, lack of drift, and high reliability. Administrative contro must insure that replacement fuses with ratings other than those selected for proper coordinating are not accidentally used.

b. For circuits of equipment and/or components whose spurious operation would affect the capability to safely shutdown:

-6 (1) provide a means to isolate the equipment and/or components from the fire area prior to the fire (i.e., remove power cables, open circuit breakers); or (2) provide electrical isolation that prevents spurious operation.

Potential isolation devices include breakers, fuses, ampli fiers, control switches, current XFRS, fiber optic couplers, relays and transducers; or (3) provide a means to detect spurious operations and then proce dures to defeat the maloperation of equipment (i.e., closure of the block valve if PORV spuriously operates, opening of the breakers to remove spurious operation of safety injection);

c. For common enclosure cases of associated circuits:

(1) provide appropriate measures to prevent propagation of the fire; and (2) provide electrical protection (i.e., breakers, fuses or similar devices)

C. We recognize that there are different approaches which may be used to reach the same objective of determining the interaction of associated circuits with shutdown sYstems. One approach is to start with the fire area, identify what is in the fire area, and determine the interaction between what is in the fire area and the shutdown systems which are outside the fire area. We have entitled this approach, "The Fire Area Approach." A second approach which we have named "The Systems Approach" would be to define the shutdown systems around a fire area and then determine

-7 those circuits that are located in the fire area that are associated with the shutdown system. We have prepared two sets of requests for informatiop, one for each approach. The licensee may choose to respond to either set of requests depending on the approach selected by the licensee.

FIRE AREA APPROACH

1.

For each fire area where an alternative or dedicated shutdown method, in accordance with Section III.G.3 of Appendix R is provided, the following information is required to demonstrate that associated circuits will not prevent operation or cause maloperation of the alternative or dedicated shutdown method:

a. Provide a table that lists all the power cables in the fire area that connect to the same power supply of the alternative or dedicated shutdown method and the function of each power cable listed (i.e., power for RHR pump).

b. Provide a table that lists all the cables in the fire area that were considered for possible spurious operation which would adversely affect shutdown and the function of each cable listed.

c. Provide a table that lists all the cables in the fire area that share a common enclosure with circuits of the alternative or dedicated shutdown systems and the function of each cable listed.

d. Show that fire-induced failures (hot shorts, open circuits or shorts to ground) of each of the cables listed in a; b, and q will not prevent operation or cause maloperation of the alternative or dedicated shutdown method.

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e. For each cable listed in a, b and c where new electrical isolation has been provided or modification to existirg electrical isolation has been made, provide detailed electrical schematic drawings that show how each cable is isolated from the fire area.

SYSTEMS APPROACH

1. For each area where an alternative or dedicated shutdown method, in accordance with Section III.G.3 of Appendix R is provided, the following information is required to demonstrate that associated circuits will not prevent operation or cause maloperation of the alternative or dedicated shutdown method:

a. Describe the methodology used to assess the potential of associated circuit adversly affecting the alternative or dedicated shutdown.

The description of the methodology should include the methods used to identify the circuits which share a common power supply or a common enclosure with the alternative or dedicated shutdown system and the circuits whose spurious operation would affect shutdown. Additionally, the description should include the methods used to identify if these circuits are associated circuits of concern due to their location in the fire area.

b. Provide a table that lists all associated circuits of concern located in the fire area.

c. Show that fire-induced failures (hot shorts, open circuits or shorts to ground) of each of the cables listed in b will not prevent operation or cause maloperation of the alternative or dedicated shutdown method.

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d. For each cable listed in b where new electrical isolation has been provided, provide detailed electrical schematic drawings that show how each cable is isolated from the fire area.

e. Provide a location at the site or other offices where all the tables and drawings generated by this methodology approach for the associated circuits review may be audited to verify.the information provided above.

HIGH-LOW PRESSURE INTERFACE For either approach chosen the following concern dealing with high-low.

pressure interface should be addresspd.

2. The residuAl heat removal system is generally a low pressure system that interfaces with the high pressure primary coolant system. To preclude a LOCA through this interface, we require compliance with the recommendations of Branch Technical Position RSB 5-1.

Thus, the interface most likely consists of two redundan and independent m9tor operated valves. These two motor operated valves and their associdted cables may be subject to a single fire hazard. It is our concern that this single fire could cause the two valves tq open rpsulting in a fire initiated LOCA through the high-low pressure system interface. To assure that this interface and other high-low pressure interfaces are adequately protected from the effects of a single fire, we require the following information:

a. Identify each high-low pressure interface that uses redundant electrically controlled devices (such as two series motor operated valves) to isolate or preclude rupture of any primary coolant boundary.

01 10

b. For each set of redundant valves identified in a., verify the redundant cabling (power and control) have adequate physical separation as required by Section III.G.2 of Appendix R.

c. For each case where adequate separation is nct provideU, shfo: that fire induced failures (hot short, open circuits or short to ground) of the cables will not cause maloperation and result in a LOCA.

OITERIA FOR EVALUATING W

EXEMPTIONS TO SECTION III G OF APPENDIX R OF 10 CFR PART 50 Paragraph 50.48 Fire Protection of 10 CFR Part 50 requires that 011 nuclear power plants licensed prior to January 1, 1979 satisfy the requirements of Section III.G of Appendix R to 10 CFR Part 50.

It also requires that alternative fire protection configprations, previously approved by an SER be reexamined for compliance with the requirements of Section III.G.

Section III.9 is related to fire protection features for ensuring that systems and associated circuits used to achieve and maintain safe shutdown -are free of fire damage.

Fire protection gonfigurations must either meet the specific requirer ments of Section'III.G or an alternative fire protection configuration must be justified by a fire hazard analysis.

The general criteria for accepting an alternative fire protection configur ations are the foll9wing:

The alternative assures that one train of equipment necessary to achieve hot shutdown from either the control room or emergency control stations is free of fire damage.

The alternative assures that fire damage to at least one train of equipment necessary to achieve cold shutdown is limited such that it can be repaired within a reasonable time (minor repairs with cqiponents stored on-site).

Fire retardant coatings are not used as fire barriers.

.Moqdifications required to meet Section III.G woul.not enhanqp fire protection safety above that provided by either existing or proposed alternatives.,

Modifications required to meet Section III.G would be detrimental to overall facility safety.

Because of the broad spectrum of potential configuration$ for which exemptions may be requested, specific criteria that account for all of the parameters that are important to fire protection and consistent with safety requirements of all plant-unique configurations have not been developed.

However, our evaluations of deviations from these require ments in our previous reviews and in the requests for III.G exemptions received to date have identified some recurring configurations for which specific criteria have been developed.

-2 Section III.G.2 accepts three methods of fire protection.

A passive 3-hour fire barrier should be used where possible.

Where a fixed barrier cannot be installed, an automatic suppression system in combination with a fire barrier or a separation distance free of combustibles is used if the configurations of systems to be protected and in-situ combustibles are such that there is reasonable assurance that the protected systems will survive.

If this latter condition is not met, alternative shutdown capa bility is required and a fixed suppression system installed in the fire area of concern, if it contains a large concentration of cables. It is essential to remember that these alternative requirements are not deemed to be equivalent. However, they provide adequate protection for those configurations in which they are accepted.

When the fire protection features of each fire area are evaluated, the whole system of such features must be kept in perspective.

The defense in-depth principle of fire protection programs is aimed at achieving an adequate balance between the different features.

Strengthening any one can compensate in some measure for weaknesses, known or unknown in others.

The adequacy of fire protection for any particular plant safety system or area is determined by analysis of the effects of postulated fire relative to maintaining the ability to safely shutdown the plant and minimize radio active releases to the environment in the event of a fire. During these evaluations it is necessary to consider the two-edged nature of fire protection features recognized in General Design Criterion 3 namely, fire protection should -be provided consistent with other safety considerations.

An evaluation must be made for each fire area for which an exemption is requested. During these evaluations, the staff considers the following parameters:

A. Area Description walls, floor, and ceiling construction ceiling height room volume ventilation congestion B. Safe Shutdown Capability number of redundant systems in area whether or not system or equiment is-required for hot shutdown type of equipment/cables involved repair time for cold shutdown equipmnt within this area separation between redundant components and in-situ concentration of combustibles

-alternative shutdown capability

-3 C. Fire Hazard Analysis type and configuration of combustibles in area quantity of combustibles ease of ignition and propagation heat release rate potential transient and installed combustibles suppression damage to equipment whether the area is continuously manned traffic through the area accessibility of the area D. Fire Protection Existing or Committed fire detection systems fire extinguishing systems hose station/extinguisher radiant heat shields A specific description of the fire protection features of the configuration is required to justify the compensating features of the alternative. Low fire loading is not a sufficient basis for granting an exemption in areas where there are cables.

If necessary, a team of.experts, including a fire protection engineer, will visit the site to determine the existing circumstances. This visual inspection is also considered in the review process.

The majority of the III.G exemption requests received to date are being denied because they lack specificity. Licensees have not identified the extent of the exemption requested, have not provided a technical basis For the request and/or have not provided a specific description of the alternative. We expect to receive requests for exemption of the following nature:

1.

Fixed fire barriers less than 3-hour rating.

2. Fire barrier without an automatic fire suppression system.

3. Less than 20 feet separation of cables with fire propagation retardants (e.g., coatings, blankets, covered trays) and an automatic suppression system.

4. For large open areas with few components to be protected and few in-situ combustibles, no automatic suppression system with separation as in Item

) above.

5. No fixed suppression in the control foom.

-4

6.

No fixed suppression in areas without a large concentration of cables for which alternative shutdown capability has been provided.

Our fire research test program is conducting tests to provide information that will be useful to determine the boundary of acceptable conditions for fire protection configurations which do not include a fire rated barrier.

Based on deviations recently approved, specific criteria for certain recurring configurations are as follows:

Fire Barrier Less than Three Hours This barrier is a wall, floor, ceiling or an enclosure which separates one fire area from another.

Exemptions may be granted for a lower rating (e.g., one hour or two hours) where the fire loading is no more than 1/2 of the barrier rating. The fire rating of the barrier shall'be no less thaq one hqur, Exemptions may be granted for a fixed barrier with a lower fix rating supplemented by a water curtain.

An Automatic Suppression System With Either One Hour Fire Barrier or 20-Foot Separation This barrier is an enclosure which separates those portions of one division which are within 20 feet of the redundant division.

The suppressant may be water or gas.

Exemptions may be granted for configurations of redundant systems which have compensating features. For example:

A. Separation distances less than 20 feet may be deemed acceptable where:

1. Fire propagation retardants (i.e., cable coatings, covered trays, conduits, or mineral wool blankets) assure that fire propagation through in-situ combustibles will not occur or will be delayed sufficiently to ensure adequate time for detection and suppression.

2.

Distance above a floor level e..osure fire and below ceiling assures that redundant systems will not be simultaneously subject to an unascceptable temperature or heat flux.

B.

The ommission of an automatic suppression system may be deemed acceptable where:

1.

Distance above a floor level exposure fire and below ceiling assures that redundant systems will not be simultaneously subject to an unacceptable temperature or heat flux.

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.2.

The fire area is required to be manned continuously by the provisions in the Technical Specifications.