ML20053D340
| ML20053D340 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 05/18/1982 |
| From: | Harold Denton Office of Nuclear Reactor Regulation |
| To: | COMMONWEALTH EDISON CO. |
| Shared Package | |
| ML20053D333 | List: |
| References | |
| GL-81-12, NUDOCS 8206040320 | |
| Download: ML20053D340 (26) | |
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NUCLEAR REGULATORY COMMISSION In the Matter of
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COMM0HWEALTH EDIS0N COMPANY
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Docket JJo. 50-10 (Dresden Station Unit 1)
EXEMPTION I.
The Commonwealth Edison Company (the licensee) is the holder of Facility Operating License No. DPR-2 which authorizes operation of Dresden Station Unit No. 1.
This license provides, among other things, that they are subject to all rules, regulations and Orders of the Comission now or hereafter in effect.
The facility comprises a boiling water reactor at the licensee's site located in Grundy County, Illinois.
II.
On November 19, 1980, the Commission published a revised Section 10 CFR 50.48 and a new Appendix R to 10 CFR 50 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, which specify requirements for fire protection features at nuclear power plants.
8206040320 820518 DRADOCK0500g
. By letter dated March 6,1981, the Commission granted Commonwealth Edison an extension of the completion date required in 10 CFR 50.48(d) to the dates required by 10 CFR 50.48(c).
By letter dated March 17, 1981 Commonwealth Edison requested, pursuant to 10 CFR 50.12, an exemption from the schedular requirements of 10 CFR 50.48 (c) and 10 CFR 50.48(d) for Dresden Station Unit 1.
The requested exemption would permit Commonwealth Edison to defer completion of the fire protection features required by 10 CFR 50.48 and Appendix R to 10 CFR 50 until prior to start up from the current refueling modification and chemical cleaning outage.
Commonwealth Edison provided the following information in support of the requested exemption:
1.
Dresden Unit 1 is currently shutdown for an extended refueling, modification, and chemical cleaning outage. Unit 1 is scheduled to remain shutdown until June 1986.
2.
There is not fuel in the reactor vessel or the primary containment sphere.
3.
All irradiated fuel is stored in the below-grade spent fuel storage pool in the fuel handling building.
4.
The stored fuel has not been irradiated in the reactor for at least 28 months.
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Fire protection features in the fuel handling building which were identified in the NRC Staff's Fire Protection Safety Evaluation Report will be installed and operational by May 1, 1981.
The required implementation date for this equipment is November 17, 1981.
Mr. Thomas Rausche of Commonwealth Edison informed the staff that t protection features committed to in CEC 0's March 17, 1981 letter were installed and operational on May 1,1981.
Based upon the above considerations, we find that the reactor is defueled and the spent fuel stored in the fuel storage building is protected by an acceptable fire protection system as described in the Stiff's August 9, 1979 Fire Protection Safety Evaluation Report.
Because of the above we find that there is no undue risk to the health and safety ~of the public involved with continued operation in the manner described. Therefore an exemption should be granted delaying the implementation of the fire protection modifications required by 10 CFR 50.48 and Appendix R to 10 CFR 50 until prior to start up from the current extended outage.
, 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 sec0rity and is otherwise in th,e public interest and hereby grants the following exemption with respect to the requirements of 10 CFR 50.48:
. 1.
Commonwealth Edison Company is exempt from the schedular requirements of 10 CFR 50.48(c)(1), (c)(2), (c)(3) and (c)(4) except for the fire protection provisions which
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apply to the fuel handling building at Dresden Unft 1; 2.
The date for submittals required in 10 CFR 50.48(c)(5) is extended until 18 months prior to the scheduled return to service for Dresden Unit 1; 3.
The date for completion of the fire protection features required by 10 CFR 50.48(c) and 10 CFR 50.48(d) is extended until prior to startup from the current outage.
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 Sl.5(d)(4) an environmental impact statement or negative declaration and environmental impact appraisal need not be prepared in connection with this action'.
FOR THE NUCLEAR REGULATORY COMMISSION
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Harold R. Denton, Director Office of Nuclear Reactor Regulation Dated at Bethesda, Maryland, this 18th day of May,1982.
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CLARIFICATION OF GENERIC LETTER t)n. February 20, 1981, generic letter 81-12.was forwarded to all reactor licensees with plants licensed prior to January 1,1979. The letter restated the require-
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ment of Section 50.48 to 10 CFR Part 50 that each licensee would be required
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to reassess areas of the plant where cables or equipment'in-Tuding associated non-safety circuits of redundant trains of systems necessary to achieve and
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maintain hot shutdown conditions are located to determine whether the require-ments of Section III.G.2 of Appendix R to 10 CFR 50 were satisfied.
Additionafly, Enclosure'I and Enclosure 2 of the generic letter requested additional
.infomation concerning those areas of the plant requiring alternative shu' tdown Section 8 of Enclosure 1 requested information for the systems, capability.
equipment and procedures of alternative shutdown capability and Enclosure 2 defined associated circuits.and requested information concerning associated circuits for those areas requiring alternative shutdown.
In our review of licensee submittals and meetings with licensees, it has become apparent that the request for information should be clarified since a lack of clarity could result in the submission of either insufficient or e,xcessive infomation.. Thus, the staff has rewritten Section 8 of Enclosure 1 and
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l aid in'the reassessments to determine compliance with the requirements of I
Sectiws III.G.2 and III.G.3 of Appendix R.
In developii.g this; rewrite we have The attached considered the-comment of the Nuclear Utility Fire Protection Group.
rewrite of the Enclosures contains no new requirements but merely attempts I
to clarify the request for additional information.
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- Licen' ees who have not responded to the February 20, 1981 generic letter, s
may choose to respond to the enclosed request for information. Since the'
. enclosed request for information is not new, but merely clarification of our previous letter, responding to it should not delay anh submittals:in progress that are based upon February 20, 1981 letter.
Licensees whose response to the February 20, 1981 letter, has been found : incomplete resulting in -
staff identifications of a major unresolved item (ise., associated circuits),
may choose to respond to pertinent sections of the enclosed request for infor-
. mation in order to close open items (i.e., open item for. assoc'iated circuits, use rewrite of Enclosure 2).
3 If additional clarification is needed, please contact the staff Project i
flanager for your plant.
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ATTACHMENT REWRITE OF.SECTION 8 REQUEST FOR ADDITIONAL IN' FORMATION
- The f.ollowing is a rewrite of the staff's request for additional infonnation concerning design modification to meet the requirements of Section III'.G.3 of Appendix R.
The following contains no new requests but is merely a rewording Section 8 of Enclosure 1 of the February 20,'1981 generic letter.
1.
Ide~ntify those areas of the plant that will not meet the requirements of
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Section III.G.2 of Appendix R and, thus alternative shutdown will be pro
, or.an exemption from the requirements of Section III.G.2 of Appendix R wi provided. Additionally provide a statement that all other areas of. the p' are or will be in compliance with Section III.G.2 of Appendix R.
For each of those fire areas of the plant requiring an al.ternative. shutdot system (s) provide a complete set of responses to the following requests ft
~each fire area:
a.
List the system (s) or portions thereof used to provide the shutdown capability with the loss of offsite power.
- b. ' For those systems identified in "la" for which alternative or dedica9 shutdown capability must be provided, list the equipment and componea of the normal shutdown system in the fire area and identifp the func9 of the circuits of'the normal shutdown system in the fire area (poweE equipment, control of what components and instrumentation).
Descr'ibG the system (s) or portions thereof used to provide the alternative she j
capability for the fire area and provide a table that lists the equig and components of the cit'ernative shutdown system for the fire area.
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" 2-
- i For each alternative system ident fy the function of the new circuits being provided.
Identify the location (fire zone) of the
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alternative shutdown equipment and/or. circuits that bypass the fire area and verify that the alternative shutdown equipment and/or circuits are separated from the. fire area in accordance with Section III.G.2.
- c. ' Provide drawings of the alternative shutdown system (s) which highlight any connections to the normal sh' tdown systems (P& ids for pip 1ng ana components.
u elementary wiring diagrams of electrical cabling). Show the electrical
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location of all breakers for power cables, and isolation devices for
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control and instrumentation circuits for the alternative shutdown systems for that fire area.
d.
Verify that changes "to safety systems -will not degrade safety systems;
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(e.g., new isolation switches and control switches should meet design criteria and standards in the FSAR.for electrical equipment in the system that the switch is to be installed; cabinets that the switches are to be mounted in should also meet the 'same criteria (FSAR) as other safety related cabinets and panels; to avoid inadvertent isolation from the control room, the isolation switches should be keylocked or alarmed in the control room if in the "Iocal" or " isolated" position; periodic checks should be made to verify that the switch is in the. proper position foc normal operation; and a single transfer switch or other new device should not be a source of a failure which causes lon_of reaunaant saft:ty:4 systems).
Verify that licensee procedures have been or Will be develo' ped' which describG er tasks to. be perfomed to effect the shutdown method.
Provide a summary
,of these procedures outlinir.g' operator actions.
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Verify that the manpower required to perform the shutdown functions using the procedures of es as well as to provide fire brigade msnbers to fight the fire is available as required by the fire brigade technical speci-fications.
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9 Provide a commitment to perform adequate acceptance tests of the alter-
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native shutdown capability.
These tests should verify that:
equipment operates from the local control station when the transfer or isolatio'n switch is placed in th'e " local" position and that the equipment cannot-be operated from the control room; and that equipment operates from'the control room but cannot be operated at the local control station when the transfer isolation switch is in the " remote" position.
h.
Provide Technical Specifications of the surveillance requirements and,
limiting conditions for operation for that equipment not already
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covered by existing Technical Specifications.
For, example, if new isolation and control switches are added to a shutdown system, the existing Technical Specification su.rveillance requirements should be. supplemented to verify system / equipment functions from the alternate shutdown station at testing intervals consistent with the guidelines of Regulatory Guide 1.22 and IEEE 338.
Credit may be taken for other existing tests using group overlap test concepts.
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For new equipment comprising the alternative shutdown capability, verify that the systems available are adequate to perform the necessary shut-down function.
The functions required should be bayed on previous analyses, if possible (e.g... in the FSAR). such as a loss of normal ac power or shutdown on Group l' isola, tion (BWR).
The equipment required for the alternative capability should be the same or equivalent to that' relied on in the above analysis.
Verify. that repair procedures for cold shutdown systens are developed
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, and material for repairs is maintained on site.
Provide a summary of these proc,edures and a.' list of the material needed for repairs.
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ATTACHMENT 2' SAFE SHUTDOWN CAPABILITY The following discusses th,e 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 fr'ee of fire damage.
The followl.ng requirements also apply to cold s,hutd'own equipment if the licensee elects to demonstrate that th,e,.equipaent.is to be, free of. fire. damage.
AppendUc R does allow.rejairable damage to cold shutdown
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eautoment.
Us'ing the requirements of Sections III.G and III.L of Appendix R, the $2pa '
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 th'ree options as defined in Section III.G.2 pcVides methods for protection from fires of equipment needed for
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hot shutdown:
s 1.
Redundant systems including cables, equipment, and associated circuits may be separated by a three-hour fire rated barrier; or, 2.
Redun' dant systems including cables, equipment and associated circuits may t
be separated by a horizontal distance of more than 20 feet with no inter-vening. combustibles.
In addition, fire detection and an automatic fire supprdssion 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, f. ire detectors I
and an automatic fire suppression system -are required.
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..g 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 systebs damaged hy the fire.'
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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 d.efinition of associated cirguits has not changed from the Februa'ry 20, 1981 generic letter; but is merely clarified.
It is important to note that our interest is only 1
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 1
l be used only as guidancs when needed.
These guidelines do not limit the alter-natives available to the licensee for protecting tne shutdown capability.
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Al1 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 'ithin the fire area, Rill, receive fir.e damage w
which cin affect shutdown capability and thereby prevent post-fire safe sh~tdown. Associated Circuits
- of Concern are defined as those cables u
(safety related, non-safety related, Class lE, and non-Class lE).that:
- The definition for associated circuits is not exactly the same as the definition presented in IEEE-384-1977.
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3-1.
Have a physical separation less than that required by Section III.G.2 -
of Append'ix R,.and; 2.
Have one of the following:
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a common power source with the shutdown equipment (redundant or a.
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
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dump valves, instrumentation, steam bypash, etc.) (see diagram 2b), or a common enclosure (e.g., raceway, panel,, junction) with the shutdown c.
cables (redundant and alternative) and, (1) are not electrically protected by circuit breakers, fuses or simi-lar devices, or l
l (2) will ' allow propagation of the fire into the common enclosure, (see. diagram 2c).
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EXAMPLES OF ASSOCIATED CIRCUITS OF CONCERN l
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- ,,,e sp au'AES The area barriers shown above mee't the appropriate sub-paragraphs (a-f)
Ortrahi ca"bl n' 'fec/
of section III.G-2 of Appendix R.
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Diagram 2A Diagram 2B Diagram 2C e
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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 electrimal 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 protectio'n.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:
i 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 'fot)owing should apply:
l (1) The associated circuit of ~ concern interrupting devices '
(breakers o'r 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 sh'utdown loads.
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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
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verify overcurrent protection as des'igned in accordance with-the applicable UL, ANSI, or NEMA standards.
(ii)
For low and medium voltage switchgear (480 V and above)
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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.
(jii)
Molded case circuit breakers shall peridically be manually
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exercised and inspected to insure ease of operation. On a rotating refueling outage basis a' sample of these breakers shall be tested to de,termine that breaker drift is within that allowed by the design criteria.
Breakerishouldbe 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
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periodic testing, due to their stabiIity, lack of. drift, and high reliability. Adminis_trative controls must insure that replacement fuses with ratings other than those
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selected for proper coordinating are not. accidentally used.
b'.
For circuits of equipment and/or components whose spurious operation would affect the capability 'to s'afely' shutdown:
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j (1) provide a means to isolate the equipment and/or components from
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the fire area prior to the fire (i.e., remove power cables, open j
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circuit breakers); or (2) provide electrical isolation that pre 6nts sp'urious 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 spucious operations and then croce.
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 as'sociated circuits:
l (1) provide appropriate measures to prevent propagation of the
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fire; and (2) provide electrical protecti'on (i.e., breakers, fuses or similar devices)
C.
We recognize that there are,different approaches which may be used to l
' 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 outsjde the fire area.
We have entitled 'this a'pproach, "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
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those circuits that are located in the fire area that are associated with the shutdown system. We have prepared two sets of requests for
- in' formation, 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
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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 naloperation of the alternative or dedicated sh'utdown method:
Provide a table that lists all th'e power cables in the fire area a.
that connect to the same power supply of the. alternative or l
dedicated shutdown method and the functi.on of each power cable l
listed (i.e., power for RHR pump).
I b.
Provide a table that lists all the cables in the fire area that were considered for possible spurious operation which would adversely l
l affect shutdown and the function of each cable listed.
Provide a table that, lists all the cables in the fire area that l
c.
share a common enclosure with circuits of the alternative or dedicated sh'utdown sy3tems and the function of each cable listed.
l d.
Show that fire-induced failures (hot shorts, open cirgui.ts or shorts to ground) of each of the cables listed in at b, and c will not prevent operation or cause maloperation of the alternative or dedicated shutdown method.
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For each cable listed in a, b and c where new electrical iso 1'ation has been provided or modification to existir.g 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 dedi.cated 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:
Describe the methodology used to assess the potential of associated a.
circuit adversly affecting the' alternative or dedicated shutdown.
The description of the methodology should include the methods used to identify the ci,rcuits which share a common power supply or a common enclosure with the alternative or dedicated shutdown system and the circuits whose sp,urious 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 f. ire 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 alternatife or.
dedicated shutdown method.
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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.
Provide a location at the site or other offic'e,s where all the e.
tables and drawings generated by this metho'dology approac_h for the associated circuit' review may be audited to verify,the
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s information provided above.
HIGHdOW PRESSURE INTERFACE For either approach chosen the following concern dealing with high-low.
pressure interface should be addressed 2.
The residual heat removal system is generally a 1o.1 pressure system that interfaces with the high pressure primary coolat., system. To preclude a LOCA through this interface, we requi.re compliance with the recommendations of Branch Technical Position RSB 5-1.
Thus, the interface most likely consists of two redundant and independent motor operated valves. These two motor operated valves and their associdted cables maj be-subject to a single f. ire hazard.
It; is our concern that this single fire could cause the two valves to open resulting 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.
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b.
For each set'of redundant valves fdentified in a., verify the redundant cabling (power and control) have adequate physical separation as required by Section III.G.2 of Appendix P..
c.
For each case where adequate separation is r.ct provided,. shot: thct
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fire induced failures (hoti short, open circuits or short to ground).
of the cables will not cause maloperation and result in a LOCA.
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CRIT'ERIAFOREVA(UATING
,3 EXEMPTIONS TO SECTION III G OF APPENDIX R OF 10 CFR PART 50 i
Paragraph 50.48 Fire Protection of 10 CFR Part 50 requires that all nuclear power plar.ts 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 configurations,.
previously approved by an SER be reexamined for compliance with the requirements of Section III.G.
Section III.G is relqted to fire p.
protection features for ensuring that systems and risociated circuits used to achieve and maintain safe shutdown.are free of fire damage.
Fire protection configurations ~ must either meet the specific require-ments of Section III.G or an alternative fire protection. configuration -
I must be justified by a fire hazard analysis.
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The general criteria for accepting an alternative fire protection configur-ations are the following:'
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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 dainage to at least one train of equipment necessary to achieve cold shutdown is limited such that j
it can be repaired within a reasonable time (minor repairs wjth components stored on-site).
Fire retardant coatin_gs are not used as fire barriers.
Modifications required to meet Section III.G would.not enhance 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.
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l Because of the broad spectrum of potential configurations for which exemptions may be_ requested, specific criteria that' account for all of the parameters that are important to fire protection and consistent with t
i safety requirements of all plant-unique configurations have not been devel oped.
However, our evaluations of devia~tions from these require-ments in our grevious reviews and in the requests for III.G exemptions received to date have identified some recurring configurations for which specific criteria have been developed.
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Section III.G.2 accepts three methods of fire protection.
A passive k'here a fixed barrier 3-ho*ur fire barrier should be used where possible.
cannot be installed, an automatic suppression system in combination with a fire barrier or a separation distance free of combustibles is used if tihe configurations of systems to be protected and in-situ combustibles are such that there is reasonable assurance that the protected systems will If this latter condition is not met, alternative shutdown capa'-
survive.
bility is required and a fixed suppression system installed in the fire It is area of concern, if it contains a large concentration of cables.
essential to remember that these alternative requirements are'not deemed to be equivalent.
However, they provide adequate protection for those confiourations in which they are accepted.
"heri the fire protection features of each fire area are evaluated, the The defense-
..aole system of such features must be kept in perspective.
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 detemined by analysis of the effects of postulated fire relative to maintaining the ability to safely shutdownithe plant and minimize-radio-active releases to the environment in the event of a fire.
During thes,e 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 withiother safety considerations.
An evaluation cust 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 ce'iling 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 w,
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3-C., Fire Hazard Analysis type and configuration of combustibles in area quantity of combustibles case of ignition and propagation heat release rate. potential transient and installed combustibles suppression damage to equipment
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whether the area is cc,ntinuously manned traffic through the area
~ ' accessibility of the. area D.
Fire Protection Existing or Committed fire detection systems fire extinguishing systems
. ho,s,e station / extinguisher radiant heat shields A specific description of the fire protection fe'atures of the configuration is r.equired to justify 'ihe compensating features of the alternative. Low 1
fire loading is not a sufficient basis 'for granting an exemption in areas where there are cables.
s If necessary, a team of. experts, including a fire protection engineer, l
will visit the site to determine the existing circumstances. This visual inspection is also considered in the. review process.
I The majority of the III.G exemption requests received to date are being denied because they lack specificity.
Licensees have not identified I
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:
Fix'ed fire barriers'less than 3-hour rating. '
1.
Fire barrier withet t an automakic fire suppression sy' stem.
2.
3.
Less than 20 feet separation of cables with fire propagation-
' retardants (e.g., coatings, blankets, covered thys) and an automat.ir suppression system.
For 1arge open areas with few components to be protected and few in-situ
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4.
combustibles, no automatic suppression syst.em with separation as in Item l
l 3 above.
5.
No fixed suppression in the contr'o1 foom..
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6, Th3 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'hou's) r where the fire loading is no more than 1/2 of the barrier rating. The fire rating of the barrier shall be no less than one hour.
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 red,undant division. The suppressant may be water or gas.
Exemptions may be granted for configurations of redundant systems which-
'hav'e compensating features.
For example:
A.
Separation distances less than 20 fe.et 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 combustible's will not occur or will be delayed sufficiently to ensure adequate time for detection and' suppression.
2.
Distance above a floor level exposure fire 2nd below ceiling assures that redundant systems will not be simultaneously subject to an unasceptable temperature or heat flux.
l B.
The ommission of an automatic suppression system may be deemed' acceptable where:
l 1.
Distance above a floor level exposure fire and below ceiling assures i
that redundant systems will not be simultaneously subject to an r.acccptrie temperature er heet flux.
i
a 5-
.2.
The fire area is required to be manned continuously by the provisions in the Technical Specifications.
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