ML20052H432
| ML20052H432 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 05/04/1982 |
| From: | Harold Denton Office of Nuclear Reactor Regulation |
| To: | NORTHERN STATES POWER CO. |
| Shared Package | |
| ML20052H433 | List: |
| References | |
| NUDOCS 8205210044 | |
| Download: ML20052H432 (28) | |
Text
7590-01
' NUCLEAR REGULATORY COMMISSION In the Matter of
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NORTHERN STATES POWER COMPANY Docket No. 50-263 (Monticello Nuclear Generating Plant)
EXEMPTION I.
The Northern States Power Company (the licenses) is the holder of
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Facility.0perating License No. DPR-22 which authorizes operation of the Monticello Nuclear Generating Plant. This license provides, among other things, that it is subject to all r,ules, regulations and Orders of the Comnission n'ow or hereafter in effect..
The facility is comprised of a boiling water reactor at the licensee's site located in Wright County, Minnesota.
c II.
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On November 19, 1980, the Connission 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 FR 76602). The revised Section 50.48(c) and Appendix R became effective on February 17, 1981.
Section50.48(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 nucle:ar : power plant.
One of these fifteen subsections,
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III.G., is the subject of this ' Exemption.
Subsection III.G. specifies e
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detailed requirements for fire pro'tection of tb 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 in that area, was required (III.G.3).
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 prot'ection rule, February 17, 1981, except for modifications to provide alternative safe shutdown capability. These latter modifications (III.G.3) 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 13, 1981, as amended December 3,1981, and February 15, 1982, Northern States Power Company requested exemptions from 10 CFR 50.48(c) with respect to the requirements of Section III G of Appendix R as follows:
(1)
Extend from March 19, 1981 to July 1,1982, the date for submittal of plans and schedules to achieve compliance with III.G.2 requiIed
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by Section.50.48(c)(5);
(2)
Extend from March 19, 1981, to July 1,1982, the date for filing additional exemptions from III.G. pursuant to Sections 50.12(a) and 50.48(c)(6);
'(3) Extend from March 19,1961,.to July.1,1982, the date for submittal of -
design descriptions of alternative or dedicated shutdown systems to comply,-with Section I;II.G.3., if such are necessary; and (4)
Extend from February 17, 1981, to June 1,1982, the date from which the installationschedulesestablishedinSection50.48(c)(2)and(3) are calculated.
3 When this Fire Protection Rule was approgd by the Commission, it was understood that the time required for each licensee to reexamine 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 j
each item of nonconfomance that was found, a fire hazards analysis had to
-be perfonned 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 require-ments 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. of Appendix R.
Depending upon t,he extensiveness and number of the areas involved, the time required for this reexamination, 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
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'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
4 in a generic letter (81-12) dated February 20, t981, to the licensees of all 72 plants was not provided.
Therefore, additional time is being used to complete those submittals.
III.
Prior to the issuance of Appendix R, the Monticello Nuclear Generating P1 ant'had been reviewed against the criteria of Appendix A to the Branch
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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 the Browns Ferry Nuclear Plant.
It l
l 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 tne Standard Review Plan used for the review of applications for construction permits and operating licenses of new plants.
The review w'as 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 one supplement to the'FPSER. The FPSER and its suppl'ement supported the issuance of amendments to the operating license of the Monticello Plant 1/ which required'modifica-tions to be made to plant physical features, systems, and admini.stratiye
..- controls to meet.the criteria of Appendix A to BTP 9.5-1.
All of these..
modifications have been completed. Therefore, the Monticello Nuclear Generating Plant has been upgraded to a high degree of fire protection already 1/ onticello.- Operating Li.c.ense DPR-22 M
s Amendment 41 supported by FPSER issued August 29,1979 to Provisional Operating License No. DPR-22 Amendment i supported by Supplement 1 to FPSER issued Februa ry 12, 1981 to Facility Operating License No. DPR-22
5 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.
As mentioned earlier there are 14 other subsections which contain
, crit'eria for other aspects of fire protection features.
One of these,Section III.L., provides the criteria for Alternative and Dedicated Safe Shutdown Capabi-lity and thus affects the final reassessment and redesign, if n' cessary, of this feature at the Monticello Plant.
Nevertheless, this e
means that compliance with the remaining applicable sections of Appendix R have been or will be completed on or before the implementation dates' required by the Fire Protection Rule.
Based on the above considerations, we find that the licensee has completed a substantial part of the fire protection features at Monticello in 1
conformance with the requirements of the Fire Protection Rule and'is applying significant effort to complete the re* assessment 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 July'i,1982.
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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
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informatid'n requested by' Generic Letter 81-12 dated Februafy 20,1981, was
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provided, we are adding a condition to this Exemption that requires all such infomation to be submitted by the date granted.
6 IV.
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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-
'i Section III.G. of Appendix R to 10 CFR 50:
(1) The date, March 19, 1981, for submittal of plans and schedules to achieve compliance as required by Section 50.48(c)(5) is extended to July 1,1982; (2) The date, March 19, 1981, for filing exemption requests pursuant to Section 50.48(c)(6) which includes a tolling provision is extended to July 1,1982; (3) The date, March 19, 1981, for submittal of design descriptions of alternative or dedicated shutdown systems to comply with Section III.G.3 as required by Section 50.48(c)(5) is extended to July 1,1982; and (4) The date, February 17, 1981, from which the installation schedules established in Section 50.48(c)(2) and (3) are calculated is extended to June 1,1982.
Provided the following conditions are met:
1).
Requests for exemption pursuant to Section 50.48(c)(6) must include:
I a) A concise statement of t'he extent of the exemption; b) A concise description of the proposed alternative design features related to assuring post-fire shutdown capability; and
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c) A sound technical basis that justifies the propose ~d alternslive in terms of protection afforded to post-fire shutdown capabil,ity,
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degree of enhancement in fire safety by fuTl compliance with III.G requirements, or the detriment to plant safety incurred by full compliance with III.G. A simple statement that the' feature for which the exemption is requested was previously anproved 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.
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7 2).
The design descriptions of. alternative or dedicated shutdown systems to comply with Subsection III.G.3., as required by Section 50.48(c)(5) shall include a point-by-point response to each item in Secticn 8 of Enclosure 1 to generic letter 81-12 dated February 20, 1981, and to each item in Enclosure 2 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 violation 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 workload 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 my be imposed to be mitigated.
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 environmental. impact appraisal need not be prepared in connection, with this action.
FOR THE NUCLEAR REGULATORY COMMISSION k4tAY Harold R. Denton, Director Office of Nuclear Reactor Regulation
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Dated at Bethesda, Maryland, tnis 4th day of May 1982.
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LtJCLUSURL 2 4
i CLARIFICATION OF GENERIC LETTER On 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-ment of Section 50.48 to 10 CFR Part 50 that each licensee would be required to reassess areas of the plant whero cables or equipment including associated non-safety circuits of redundant trains of systems necessary to achieve and 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. Additionally, and Enclosure 2 of the generic letter requested additional infonnation concerning those areas of the plant requiring alternative shutdown f
capability. Section 8 of Enclosure 1 requested information for the systems, 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 information. Thus, the staff has rewritten Section 8 of Enclosure 1 and 1 of the February 20, 1981 generic letter. Additiva11y, further clarification of the definition of associated circuits has been provided to aid in the reassessments to determine compliance with the requirements of Sections III.G.2 and III.G.3 of Appendix R.
In developing this= rewrite we have considered the coment of the Nuclear Utility Fire Protection Group.
The enclosed rewrite of the Enclosures contains no new requirements but merely attempts to c.larify the request for additional information.
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2-Licensees who have not responded to the February 20, 1981 generic letter, 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 any 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 (iae., associated circuits),
may choose to respond to pertinent sections of the enclosed request for infor-f mation in order to close open items (i.e., open item for. associated circuits, use rewrite of Enclosure 2).
If additional clarification is needed, please contact the staff Project flanager for your plant.
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. ATTACHMENT 1 REWRITE OF S.ECTION 8 REQUEST FOR ADDITIONAL INFORMATION The following is a rewrite of the staff's request for additional information concerning design modification to meet the requirements of Section III'.G.3 of Appendix P..
The following contains no new requests but is merely a rewording of Section 8 cf Enclosure 1 of the February 20, 1981 generic letter.
1.
Identify those a'reas of the plant tha,t will not meet the requirements of Section III.G.2 of Appendix R and, thus alternative shutdown will.be p.rovidek
,'or an exemption from the requirements of Section III.G.2 of Appendix R will' be provided. Additionall'y pro..de a statement that all other areas of the plant are or will be in compliance with Section III.G.2 of Appendix R.
For each of thosf fire areas of the plant requiring an alternative shutdown system (s) provide a complete set of responses to the following requests for each fire area:
1 List the system (s) or portions thereof used to pro' vide the shutdown a.-
I capability with the loss of offsite power.
y.
b.
For those systems identified in "la" for which alternative or dedicated shutdown capability must be provided, list the equipment and. components of the normal shutdown system in the fire area and identiff the functions I
of the circuits of the normal shutdown system in the fire area (power to what equipment, control of what components and instrumentation').
Describe the system (s) or portions thereof used to provide the alternative shutdown capabDity for the fire area and provide a table that lists the equipment and components of the alternative shutdown system for the fire area.
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. For each alternative system identify the function of the new circuits being provided.
Identify the location (fire zone) of the 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 shutdown systems (P& ids for p1 ping ana components, i
elementary wiring diagrams of electrical cabling). Show the electrical j
location of all breakers for power cables, and isolation devices for 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; (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 se.-
control room, the isolation switches should be keylocked or alarmed in the tontrol room if in the " local" or " isolated" position; periodic checks should be made to verify that the switch is in the proper position for normal operation; and a single transfer switch'or other new device should not be a r.curce of a failure which causes loss of reounaant safety -
systems).
Verify that licensee procedures have been or will be develop' ed which describe ti e:
tasks to be performed to effect the shutdown method.
Provide a summary
,of these procedures outlining operator actions.
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Verify that the manpower required to perform the shutdown functions using the procedures of e as well as to provide fire brigade members to fight the fire is available as required by the fire brigade technical spect-fications.
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 isolation switch is placed in the " local" position and that the equipment cannot be operated from the control room; and that equipment operates from the control room but cannot be?ogerated 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 covered by existing Technical SpeciTications.
For example, if new isolation and control switches are added to a shutdown system, the existing Technical Specification surveillance 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 based on previous analyses, if possible (e.g., in the FSAR), such as a loss of normal ac power or shutdown on Group 1 isolation (BWR).
The equipment required for the alternative capability should be the same or equivalent to that relied on in the above analysis.
j Verify that repair procedures for colg shutdown systems are developed and material for repairs is maintained on site.
Provide a summary of these procedures and a listoof the material needed for repairs.
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ATTACHMENT 2
.sAE SHbTDOWN CAPA$ILITY The following discusses the requirements for -protecting redund' ant and/or 1
The alternative equipment needed for safe shutdown in the event of a fire.
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requirements of Appendix R address hot shutdown equipment which mu$t b
' free of fire damage.
The followl.ng requirements also apply to cold shutdown equipment if the licensee elects to dedonstrate that the.equipraent.is to be, free of. fir _e. damage. Appendfx R does allow.rejairable damage to cold shutdown sautoment.
Us'ing the requirements of Sections III.G and III.L of Appendix R, the c 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 eqtripment needed for hot shutdown:
1.
Redundant systems including cables, equipment, and associated circuits may be separated by a three-hour fire rated barrier; or, y...
Redundant systems including cables, equipment and associated circuits may 2.
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, i
Redundant systems including cables, egoipment and associated circuits may 3.
by enclosed by a one-hour fire rated barrier.
In addition, fire detectors and an automatic fire suppression system are required.
. 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 chan'ged 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 guidancs when needed. These guidelines do not limit the alter-natives available to the licensee for prot'ecting 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 fir _e 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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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 concern by coordinated breakers, fuses, or similar devices (see diagram 2a), or b.
a connection to circuits of equipment'whose spurious operation would adversely affact the shutdown capability (e.g., RHR/RCS isolation valves, ADS valveif, 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 y..
(2) wi.ll allow propagation of the fire into the common enclosure, (see diagram 2c).
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1 EXAMPLES OF ASSOCIATED CIRCUITS OF CONCERN l
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E u g,3,,e sg w us The area barriers shown above meet B-Bus 7
the appropriate sub-paragraphs (a-f) f *Ori ca" M G/fec/
of section III.G-2 of Appendix R.
Shakdocn Diagram 2A Diagram 2B Diagram 2C
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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 fol' lowing should apply:
(1) The associated circuit of concern interrupting devices (breakers or fuses) tirae-overcurrent trip cbpr,acteristic for all circuits faults should cause the interrupting device to interrupt the fault current prior to initiation of a trip of any upstream interruptingi evice which will d
cause a loss of the common power source, (2) The power source shall supply the necessary fault current j
for sufficient time to ensure the proper coordination without loss of function of the shutdown loads.
. 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 design criteria. Breakers should 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 controls 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:
. (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 1
circuitbreakers);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 valv'e.,1f 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., breakey,,, 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
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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 information, 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 shu,tdown 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 i
were considered for possible spurious operation wil ch 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 c will not prevent operation or cause maloperation of the alternative or dedicated shutdown method.
. e.
For each cable listed in a, b and c where new electrical isolation 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 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 comon enclosure with the alternative or dedicated shutdown system and the circuits whose spurious operation would affect Additionally, the description should i$c(ude the shutdown.
me'thods 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 l
l shorts to ground) of each of the cables listed in b will not prevent operation or cat.se maloperation of the alternatite 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 infonnation provided above.
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HIGH-LOW PRESSURE INTERFACE For either approach chosen the following concern dealing with high-low pressureinterfaceshouldbeaddressed.
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 redundant and independent motor operated valves. These two motor operated valves and their associdted cables may 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 ilterface. 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 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 sop: ration is r.ct previded, shm: th:t fire induced failures (hot short, open circuits or short to ground) l of the cables will not cause maloperation and result in a LOCA.
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(CRITERIA FOR EVALUATItIG EXEMPTIONS TO SECTION III G 0F APPEf1 DIX R OF 10 CFR PART 50
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Paragraph 50.48 Fire Protection of 10 CFR Part 50 requires that all 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 configurations, previously approved by an SER be reexamined for compliance with the requirements of Section III.G.
Section III.G 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 configurations must either meet the specific require-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 following:
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 components stored on-site).
Fire retardant coatings 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.
y,.
Modifications required to meet Section III.G would be detrimental to overall. facility safety.
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 safety requirements of all plent-unique configurations have not been devel oped.
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.
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- 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 l
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 i,n' 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 thes,e evaluations it is necessary to consider the two-edged nature of fire n features recognized in General Design Criterion 3 namely, fire proter *'
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 y..
walls, floor, and ceiling construction ceiling height room volume ventilation congestion B.
Safe Shutdown Capability number of redundant syttems in area whether or not system or equipment is required for hot shutdown type of equipment / cables involved repair time for cold shutdown equipment within this area separation between redundant components and in-situ concentration of combustibles alternative shutdown capability
. 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 Protectir.n Existing or Committed fire de' ection systems fire ex;inguishing systems ho,se station / extinguisher radiant heat shields A specific descriptica 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 tu date are being denied because they lack specificity. Licensees have not identified the extent of the exemption requested, have not provided a tech'nical 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 witis fire propagation retardants (e.g., coatings, blankets, covered trays) and an automatic suppression system.
4.
For large open areas with few components to be p.otected and few in-situ combustibles, no automatic suppression system with separation as in Item 3 above.
5.
No fixed suppression in the control room.
, 6.
No fixed suppression in areas without a large concentration of cables for which alternative shutdown capability has been providesi.
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 rore than 1/2 of the barrier rating. The fire rating of the barrier shall be no.l.ess 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 redundant division.
The suppressant may be water or gas.
Exemptions may be granted for configurations of redundant systems which
'have compensating features.
For example:
y.
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 ense e adequate time for detection and suppression.
2.
Distance above a floor level exposure fire and Lelow ceiling assures that redundant systems will not be simultaneously subject to an unacceptable 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.
r 5-2.
The fire area is required to be manned continuously by the provisions in the Technical Specifications.
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