ML20195E993

Proposed Rule 10CFR50, Station Blackout

ML20195E993
Person / Time
Issue date:	03/21/1986
From:	NRC
To:
References
FRN-51FR9829, REF-GTECI-A-44, REF-GTECI-EL, RULE-PR-50, TASK-A-44, TASK-OR PR-860321, NUDOCS 8606090321
Download: ML20195E993 (7)

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Federal Register / V 1. 51, N:. 55 / Fridry Mrrch 21, 1986 / Proposed Rules 9829

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', ow less each way than the arrangement and that a two pound subsample of th ted: March 14.19tia the top layer: the arrangement of the smallest plums in each eight pound clark, d!e layer may be the same as the top sample contains not more than th g,f,N s lay . or may be one row less one way number of plums listed for the y ety in Deputy Direc Division.

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&jhb/e - t than e arrangerment o'f the top layer. In Column C of said table. (FR 141 deks- - 8:45 eml k the 3.. -4x5 and 3%-ex4 packs the m coM se Y c TABLEI face of ch half of the crate shall be N 9 packed a a unit. with no shim between 'I the two b kets. 8 c ,,,,

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(2) The d meter of the smallest and g

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$,,c. NUCI. EAR RE TOFL largest plum m any mdividual pack or gggg container sha not vary more than one- g 8

,,,,,,_ ,, ,7 fourth (%) inch except that plums which .me,. er is 10 CFR Part 50 0) are placed in vo me-fill or tight-fill type containers and h ve a diameter of two N an

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$ Station Blackout is Cr, b

and one-fourth (25 inches or larger amaa Rosa - - - rr se AGENCY: Nuclear Regulatory shall not vary more han three-eights U, *,**,,,, $ N Commission.

(%) inch. A totalof t more than five f

,e== e*",,,n, _ / $ AcVioN: Proposed rule.

(5) percent. by count, f the plums in any , , ,a._ $.

5 u package or container y fail to meet emm ,_ se 'e suesMARY: ne Nuclear Regulatory this requirement. c.nwn s.,n. "

c., ,,,, E U Commission is proposing to amend its can-. so 'e regulations to require that light-water-(d) When used herein " 'ameter" shall Q;d,,,t E $ cooled nuclear power plants be capable have the same meaning as et forth in ao,,, . es is of withstanding a totalloss of the U.S. Sandards for Grade of Fresh Plums and Prunes (7 CFR 51.

• to p 5 y attemating current (AC) electric power

, se is (called " station blackout") for a 51.1538) and all other terms s 11 have Fa., se is specified duration and maintaining the same meaning as when use in the amended marketing agreement nd U

G, pou U

s' N reactor core cooling during that period.

his proposed requirement is based on order. "No.1:'.B standard fruit bo " , s"",'m $ information developed under the measures 2% to 7%x11%x16% in hes. ,. $7 is Commission's study of Unresolved "No. 22D standard lug box" measu es y Dja U Safetyissue A-44," Station Blackout."

2% to 7%x13%x16% inches. "No. ' G

,,, E mne i em se 'o ne proposed change is intended to standard lug box" measures 7% to (nw. u is

'*'* s.nia aano provide further assurance that a station 7%x13%x15% inches. All dimensions t,,, s ,,, .nw s-. . e4 tr blackout (loss of both offsitd power and are given in depth (inside dimensions teo muu _ es n'

" onsite emergency AC power systems) by width by length (outside dimensi ns

3. Section 917.400 would be revi d to O

E se N w 11 not adversely affect the public is health and safety.

read as follows: P'**a' - 67 'S Pnrm. Blata . . se is DATE:The comment period expires on Subpart-Grade and S,ze Reg lation O e us E

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N June 19,1906. Comments received after

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20 this date will be considered ifit is j 917.460 Plum Regulation t9. a n,~

o $ $ practical to do so, but assurance of (a) No handler shall ship y lot of a se is consideration cannot be given except as packages or containers of y plums Zd y $ to comments received before this date.

unless such plums grade - least U.S. a 50 '*

No.1. except that maru , y shall be ADDRESSES: Send comments to:De D,,,n U $ Secretary of the Commission, U.S.

determined by the app tion of color no, , -- A 7* 28 standards by variety such other tests Nuclear Regulatorv Commission, s,a n,o.",, ,,,, U Washington DC 20555, Attention:

as determmed to be roper by the  % ,,, _

,,, ,,,u, E,a Federal State Inspe tion Sem,ce.

20 Docketing and Service Branch. Copies of si.none __._ . as s' Internal discolora on not considered " " "-

• meu mived m be unsed serious damage - d healed growth and copied for a fee at the NRC Public Document Room.1717 H Street. NW.,

cracks emanati g from the step end (c) No hand r shall ship any package which do not ause senous damage Washington, DC.

or container of ny variety of plums not shall be pe itted. In addition to the specifica!!y nam in paragraph (b) of ..

above, any ot of Tragedy or Kelsey this section, unles such plums are of a Alan Rubin, Division of Safety Review plums sha be permitted and additional size that an eight p nd sample and Oversight, Office of Nuclear 10 perc tolerance for defects not representative of the izes of the plums Reactor Regulation. U.S. Nuclear conside ed serious damage. in the package or cont 'ner contains not Regulatory Commission, Washington, (b) handler shall ship any package more than 139 plums, an that a two DC 20555. Telephone: (301) 492-8303.

or ot r container of any variety of pound subsample of the s allest plums $UPPLEMENT ARY INFORM ATION:He plu listed in Column A of the in each eight. pound sampt contains not alternating current (AC) electric power foll ing Table I unless such plums are more than 38 plums. for essential and nonessential service in of size that an eight. pound sarnple, (d) As used herein. "U.S. N 1" and , a nuclear power plant is supplied re esentative of the sizes of the plums " serious damage" mean the se e as primarily by offsite power. Redundant in he package or container. contains not defined in the United States Sta dards onsite emergency AC power systems are re than the number of plums listed for for Crades of Fresh Plums and nes (7 also provided in the event that all offsite t variety in Column B of said table. CFR 51.1520 through 51.1538). power sources are lost.These systems ,

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. 9830 Federal Register / Vol. 51, No. 55 / Friday, March 21, 1986 / Proposed Rules .

provide power for various safety as an Unresolved Safety issue (USI): a indicated a variety of potentially i systems including reactor core decay- Task Action Plan (TAP A-44) was important failure causes. However, no heat removal and contatnment heat issued in July 1980, and work was single improvement was identified that initiated to determine whether could result in a significant removal which are essential for preserving the integrity of the reactor additional safety requirements were improvement in overall diesel generator core and the containment building, needed. Factors considered in the reliability. Data obtained from operating respectively. The reactor core decay analysis of risk from station blackout experience show that the typicci h l heat can also be removed for a limited included: (1) The likelihood and duration individual emergency diesel generator i time period by safety systems that are of the loss of offsite power:(2) the failure rate is about 2.5 x 10-8 per a, l reliability of the onsite AC power demand (i.e., one chance of failure in 40 -

independent of AC power.

)s The term " station blackout" means system; and (3) the potential for severe demands), and that the emergency AC i i the loss of offsite AC power to the accident sequences after a loss of all AC power system unavailability for a plant essential and nonessential electrical power, including consideration of the which has two emergency diesel i

} capability to remove core decay heat generators, ene of which is required for t buses concurrent with turbine trip and

- the unavailability of the redundant without AC power for a limited time decay heat removal. is about 2 x 10-8 onsite emergency AC power systems period. per demand (NUREG/CR-2989).

(e.g., as a result of units out of service The technical findings of the staff's

• Civen the occurrence of a station 4 for maintenance or repair, failure to studies of the station blackout issue are blackout, the likelihood of resultant core  :

- start on demand. or failure to continue presented in NUREG-1032. " Evaluation damage or core melt is dependent on the j' to run after start). If a station blackout of Station Blackout Accidents at Nuclear reliability and capability of decay heat persists for a sufficient time during Power Plants. Technical Findings removal systems that are not dependent which Jhe capability of the AC- Related to Unresolved Safety Issue A- on AC power. If sufficient AC-independent systems to remove decay 44."

• Additionalinformation is independent capability exists, c heat is exceeded core melt and provided in supporting contractor additional time will be available to -

containment failure could result. reports: NUREG/CR-3220. " Station restore AC power needed for long-term The Commission's existing regulations Blackout Accident Analyses" published cooling (NUREG/CR-3226).

establish requirements for the design in May 1983; NUREG/CR-2989'

• It was determined by reviewing and testing of onsite and offsite electric " Reliability of Emergency AC Power design, operational, and site-dependent power systems that are mtended to System at Nuclear Power factors that the expected frequenci of' reduce the probability oflosing all AC Plants" published in July 1983; and core damage resulting from station ~

power to an acceptable level. (See NUREG/CR-3992 " Collection and blackout events could be maintained General Design Criteria 17 and 18,10 Evaluation of Complete and Partial near or below 10-* per reactor-year for CFR Part 50. Appendix A.)The existmg Losses of Offsite Power at Nuclear any nuclear plant with readily regulations do not require explicitly that Power Plants" published in February achievable diesel generator reliabilities, s nuclear power plants be designed to 1985.8 The major results of these studies provided that the plant is designed to assure that the core can be cooled and are given below. cope with station blackout for a the mtegrity of the reactor coolant

• Losses of offsite power can be specified duration. The duration for a pressure boundary can be maintamed characterized as those resulting from specific plant is based on a coriparison for any specified period ofloss of all AC plant-centered faults, utility grid of the plant's characteristics t , those power. - blackout, and severe weather-induced factors that have been iderc <ied as the As operating experience has failures of offsite power sources. Based on operatmg experience, the frequency main contributors to risk i im station accumulated. the concern has arisen that the reliability of both the onsite and of totallosses of offsite power in blackout (NUREG-10327 operating nuclear po er plants was As a result of the station blackout j offsite emergency AC power systems studies, improved guidance will be might be less than originally anticipated, found to be about one per 10 site-years.

'6 provided to licensees regarding even for designs that meet the The median restoration time was about maintaining minimum emergency diesel requirements of General Design Criteria one-half hour, s.nd 90 percent of the offsite power losses were restored in generator reliability to minimize the 17 and 18. Many operating plants have experienced a totalloss of offsite power, approximately 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> (NUREC/CR- probability of losing all AC power. In addition, the Commission is proposing to

• and more occurrences can be expected 3992).

I a The review of a number of amend its regulations by adding a new in the future. Also, operating experience representative designs of onsite 150.63 and by adding a new final

.fv with onsite emergency power systems has included many instances when emergency AC power systems has paragraph to General Design Criterion 17, Appendix A of to CFR Part 50, to

, diesel generators failed to start. in a few cases, there has been a complete loss of i Drari tMEG-1032 wu issued for puldm requim Oat 80, nuclear power plants be both the offsite and the onsite AC power comment on june 1s.19as. Copies of this report are CapabIe of Copmg with a station

!t ava'lable for pubuc inspection and copyins for a fee blackout for some specified period of

!! systems.During these events. AC power was restored in a short time without any at the NRC Public Document Room at 1717 H Street. time.The period of time for specific

$fMc2"'iS2ma '" *"[hy' $*n*s to plant would be determined based on the lf serious consequences.

In 1975, the results of the Reactor st the Pubhcation Services Section. Room P-130A. existing capability of the plant as well Safety Study (WASil-1400) showed that Division of Techmcal Information and Document as a comparison of the individual plant

C "" l. U S. Nucleat Regulatory Commins on-

station blackout could be an important design with factors that have been contributor to the total risk from nuclear ""cIpfejf identified as the main contributors to s e curnents are avamie for risk of core melt resulting from station power plant accidents Although this pubhc inspection and copyins for a fee at the NRc total risk was found to be small, the Putshc Document Room at 1717 H Street. NW blackout.

relative importance of the station Washmaton. DC 20sss. Copies may also be These factors, which vary pu u' significantly from plant to plant because Q 8tti I

blackout accident was established. , b pe; i Subsequently, the Commission of considerable differences in design of Documents. us covernment Prinuns OfGce. P.O.

n' designated the issue of station blackout Boa 370s2. washinston DC 2001s-70s2. plant electric power systems as well as

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- Federal Register / Vol. 51 No. 55 / Friday, March 21, 1988 / Proposed Rules 9831 site-specific considera tions, include: (1) in this guide would result.tn selection of on stationtlackout. We will be Redundancy of onsita emargency AC a 4-hour or8-hour station blackout. interested in comments received anti power sources (Le number of sources duration, depending'on the specific plant staff responses associated with analysis minus the number needed for decay heat design and site-related characteristics. of cost benefit. value impact, and safety removal (2) reliabihty of onsite However, applicants and licensees improvements and the station blackout emergency AC power sources (usually could propose alternative methods to standing on the overall risk (e.g.. Is the diesel generators). (3) frequency of loss that specified in the regulatory guide in reduction of risk only a small percentage of offsite power, and (4) probable time order to justify other minimum durations of the overall risk or is it a major to restore offsite power. He frequency for station blackout capability. component of an already small risk?).

of loss of. and time to restore offsite if the proposed rule and regulatory This will be one of the first proposed power are related to grid and guide are issued, those plants with an rules to be evaluated by the NRC under switchyard reliabilities, historical already low risk from station blackout its new backfitting requirements. We weather data for severe storms, and the would be required to withstand a station would be particularly interested in availability of nearby alternate power blackout for a relatively short period of specific comments asseasing whether or sources (e.g, gas turbines). Experience time and probably would need few,if not this proposal meets the " substantial has shown that lor.g duration offsite any, modifications as a result of the rule. increase in the overall protection cf the power outages are caused primarily by Plants with currently gher risk from public health and safety . . .** threshold severe storms (hurricanes, ice. snow, station blackout wou d be required to now required by the backfit rule.

etc.). withstand somewhat longer duration The objective of the proposed rule is blackouts. Depending on their existing Separate Views of Comenissioner to reduce the risk of severe accidents capability, these plants might also need Asselstine resulting from station blackout by to make modifications (such as I support the proposed rulemaking but maintaining highly reliable AC electric increasing station battery capacity or believe substantial additional safety -

power systems and, as additional condensate storage tank capacity) In improvements beyond those called for in defense-in-depth, assuring that plants order to cope with the langer station this rulemaking are achievable and can cope with a station blackout for blackout duration.He proposed rule practicable. How to prevent and some period of time. If the proposed rule would require licensees to develop, in mitigate a station blackout event is one is adopted, all licensees and applicants consultation with the Office of Nuclear would be required to assess the of the most'significant unresolved safety Reactor Regulation, proposed plant

• issues associated with nuclear power capability of their plants to cope with a station blackout (i.e., determine the specific schedules for implementation of plants. Extended station blackout,can any needed modifications.

amount of time the plant can maintain result in core meltdown and loss of core cooling and containment integrity Additional Comments by the containment integrity. Since existing with AC power unavailable), and to Commission mitigation features such as containment have procedures and traming to cope ne proposed rule does not require spray would be inoperable, a station with such an event. Plants would be that a single failure be assumed blackout could result in a large release required to be able to cope with a concurrent with a station blackout f rads'oactive materiaI to the specified minimum duration station because station blackout goes beyond envir nment.

blackout selected on a plant-specific the normal single failure criterion. Hat Countries abroad that have made a basis, is, for a station blackout to occur, four serious commitment to nuclear power On the basis of station blackout AC power supplies must fail (two offsite and to nuclear safety have, or are studies conducted for USI A-44, and sources and two safety-related onsite planning, backfit features which presented in the reports referenced emergency AC sources).%e staff's markedly reduce station blackout risks.

above, the NRC staff has developed a estimated probability of the concurrent For example, the new French 1300 MWe draft regulatory guide entitled " Station failure of all four power supplies leads nuclear power plants are designed with Blackout.-s which presents guidance on us to believe that the staff should give a goal of coping with a station blackout (1) maintaining a high level of reliability further consideration to upgrading to for at least 20 hours2.314815e-4 days <br />0.00556 hours <br />3.306878e-5 weeks <br />7.61e-6 months <br />. According to the for emergency diesel generators. (2) safety grade the plant modifications NRC staff, the design features that developing procedures and training to needed (if any) to meet the proposed provide this capability (listed below) restore offsite and onsite emergency AC rule. Upgrading to safety grade will permit the plant to withstand a station power should either one or both become further ensure appropriate licensee blackout for three days.

unavailable. and (3) selecting a plant. attention is paid to maintaining a high

• A steam-driven generator provides specific minimum duration for station state of operability and reliability. The power for a small positive displacement blackout capability to comply with the Commission believes that the question pump that supplies cooling for reactor proposed amendment to General Design of quahty classification of modifications coolant pump (RCF) seals and also Criterion 17. Application of the methods should be addressed by interested provides power for instrumentation and parties in comments on the proposed controls and control room lighting

• A nonce of andatnuty and request for rule. necessary to withstand a station comments on the dren resulatory suide wdl b in addition to comments on the merits blackout. His design feature, which is pubhshed witha a few days of tbs Notice of of the proposed ruIe. the Commission also being backfitted onto all operating Proposed Rulemahng. Copies of the draft regulatory specifically requests Comments on 900 MWe nuclear plants in France.

Ny*nslo'r's fNt UheNd"bi7$$t noum wMer b baMd anaWe b h Me dbu M bh h %d b at im H Strut. NW., Washinston. DC 20655. and adequately implements the Backfit Rule, ability to cope with a station blackout-wiu be distnbuted to those on the automatic to CFR 50.109. RCP seal cooling with AC power distnbution het for draft regulatory guides. Free unavailable and battery depletion.

"8 '"P 'h' d'* f' "8"I*y guide ma y b, Additional Comments by

• Two turbine-driven auxilla

$No shi$tIDha"oIs"/rfe*n# ion'*lsny Conunissioners Roberts and Zech feedwster(AFW)pumpsincitd din the Director. Division of TechnicaHaformaHon and We agree with soliciting public 1300 MWE French design in addition to Document Control comments on the proposed rulemaking two motor-driven AFW pumps. Most I

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, M Federal Register,[Yel81D Es / Priday. March 21,1986' / Proposed Rules l

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' weterseesters hees W- ==

• and the finding of no N-.. mental relations. Nuclear l

? one'N*: * - . ' nA

"-@_ 'ljamagHas,s;a:m si=nh* impact are spaalable froen Mr. power plants and reactors. Penalty. I edelluss As :- --

_ , , La WarrenM!nnees, Office of Nuclear Radiation protection. Reactor siting

, Thomafore, the Femach desta provislas . Ranciar Regulation. US Narlaar criteria. Reporting and recordkeeping addisonalred-lancyin the AC- Regulatory Commission. Washington. requirements.

independent trains of the AFW system. DC 20555. Telephone: t3G1) 492-7827.

• Gravity feed back-up water supply For the reasons set out in the

[ Paperv'erk. Reduction Act Statement preamble and under the authority of the from onsite scaces to the condensate storage tank provides additional water This proposed rule amends Atomic Energy Act of 1954, as amended,

[!'l for decay heet ternoval via the AFW information collection requirements that the Energy Reorganization Act of 1974.

as amended, and 5 U.S.C. 553. the NRC

< system for long-duration station are subject to the Paperwork Reduction s blackout events. Le up to three days. Act of 1980 (44 USC. 3501 et seq.). This is proposing to adopt the following

j This three-day station blackout rule has been subs itted to the Office of amendments to 10 CFR Part 50.

.4 capability would permit sufficient time Management and Budget for review and 1

to connect a mobile gas turbine approvalof the paperwork PART SD-DOteESTIC LICENSING OF generator to provide powerif AC power seguirements. PRODUCTION AND UTIUZATION I

apuld not be nestored fme other.

Regulatory Analysis , I preferred sources. A mobde gas turbine The Comission has prepamd a 1.%e authority citation for Part 50 '

1.

. genertor is located at or in the vicinity contmues to read as follows: l of every nuclear power plaat site in regulatory analysis for this regulation.

I France. These improvements in safety The analysis examines the costs and Anthority: Secs. tos. to4.1st,182.1a3. taes I

. are being achieved at not unreasonabie benefits of the rule as considered by the iso. ea stat. sae, e37. sea, es3. 954, ess, eso, se 1 3 costs and are being d iven by the French Cosamiesion. A copy of the regulatory smana.d sac 234, as stat.1244, as amended h goalof achieving a probability of one in analysis. NUREG-1100. For Comment. (42 U.S.C. 2133. 2134. 2201. 2232, 2233, 2236

'L ten mihn (tr) per reactor-year for a "Repdatory Analysis for the Resolution 223s. 22a2); secs. 201. 2nz 20s, as Stat.1242.

% major event auch as stationm% of Unresolved Sefety Issue A-44. Station 1244 :24s. as amended (42 U.S.C. ss41. ss42.

The Co=mi==ma's role proposes much Blackout"(Published in January 1986). is 5846). unless otherwise noted.

less.It proposes an objective of one in avadable for inspection and copying for Section 50 7 also issued under Pub

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one hundred A-nd (10-8) per reacter. a fee at the NRC Public Document

' Room.1717 H Street. NW. Washington, year for station blackout,-d core 7d). . 50 nd meltdown and an objective of only DC 20555. Free single copies of Draft 1 about tour hours coping capabnity. NUREG-1109 may be obtained by M W 96

.I I would apprecate comments on wnting to the Publication Services StaL 2071,2073 (42 USC. 2133,2239).

X whether the NRC should require Section. Room P-130A. Division of Section 50.78 aise issued under sec.122 I substantial improvements in safety with TechnicalInformation and Document 68 Stat. 939 (42 USC.2152). Sections 50.8m81 also issued under sec.184. 68 1 respect to station blackout. like those Control. U.S. Nucleat Regulatory j" being accomplished in other countries. Commission. Washington. DC 20555. Stat. 954, as amended (42 USC. 2234).

which can be achieved at reasonable The Commission requests public Sections 50.100-50.102 also issued under cost and which go beyond those comment on the regulatory analysis. sec.188. 68 Stat. 955 (42 USC. 2238).

proposed in this rulemaking. Comments on the draft analysis may be For the purposes of sec. 223,68 Stat.

Mnding of No Segnsficant Eavsromnental submitted to the NRC as indicated under 958. as arnended (42 USC. 2273).

the Aconseses heading. Il 50.10(a). (b). and (c). 50.44,50.46.

I W ^'*N8 07 50.48,50.54. and 50.80(a) are issued The Commission has determine under Regulatmy FlexMty CurtiFacation under sec.161b 68 Stat.948, as the National Environmental Policy Act in accmedance with the Regulatory amended (42 USC. 2201(b)); iI 50.10(b) y of 1969, as amended, and the Flexibility Act of 1980. 5 USC. 605(b), and (c) and 50.54 are issued under sec.

I)l

1, Commission's regulations in Subpart A thecammission hereby certifies that 1611,68 Stat. 949, as amended (42 USC.

'! of 10 CFR Part St. that this rele,if ~ ' this proposed rule,if pmmulgated, will 2201(i]); and ii 50.55(e). 50.59(b). 50.70.

? ad@ted, would not be a major Federal not have a significant economic impact 50.71. 50.72. 50.73. and 50.78 are issued  !

q action significantly affecting the quality' on a substantwl number of small under sec.1610,68 Stat. 950, as

' of the human environment, and entities.nis proposed rule specifies amended (42 U.S.C. 2201(o)).

therefore an environmentalimpact that nuclear power plants be able to 2. In 150.2 a definition of" station ,

., statement is not required.%ere would w6thstand a totalloss of AC power for a blackout"is added in the alphabetical  !

not be any adverse environmental ' specified tinae duration and maintain '

impacts as a result of the peoposed nde nertuence tn read as folla -

, reactor core cooling during thet period. q 3 for the following reasons:(1)Dere These facihties are licensed under the i 50.2 Definmons. ,

, would be no additional radiological provisions of to CFR 50.21(b) and to * * * * * '

exposum to the general public or plant CFR 50.22. ne companies that own " Station blackout" means the employees, and (2) plant shutdown is these facilities do not fall within the

., complete loss of alternating current (AC) not required so there would be no scope of "small entitles" as set forth in electric power to the essential and -

additional environmental impacts as a the Regulatory Flexibility Act or the result of the need for replacement - small business size standards set forth nonessential switchgear buses in a nuclear power plant (i.e. loss of the

)

power.De enviromnental assessment in regulations issued.by the Small offsite electric power system concurrent and finding of no significant knpact on Business Administration in 13 CFR Part with turbine trip and unavailability of which this determination is besed are 121.

4 the onsite emergency AC power <

availaWe for inspection and copying for 8ystem).

e a fee at the NRC Public D6cument I.lst of Sol 4ects in 10 CFR Part BS ij

] Room.1717 H Street. NW. WasWagton.

DC. Single copies of the environmental Antitrust. Clascified information. Pire prevention. Incorporation by reference,

3. A new i 50.63 is added to read as follows:

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Federal Register /..Vol. 51. No-55 / Friday. Mamh 21. 1966 / Proposed Rules 9833

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- l 58.43 nLeen of as afternesingcurrent Commiselors will notify the licensee of - likelihood of their sinaultaneous failure under Powerg . . -. Its determination of the specified station operating and poetulated accident and (a) Regtrimmenta Eaolelight-water- blackout duration to be used in environmental conditions. A switchyard .

- cooled nuclear power plantlicensed to determining compliance with General C " ' both circuita is acceptable. Each operata must be abla to withstand and Design Criterion 17 of Appendix A of f,""g*,s ble i flic e t m owi loss of recover from a station blackout as this part.

defined in i 50.2 for a specified duration all onsite alternating current power supplies (d) Implementation-Schedulefor and the other offsite electric power circuit. to in accordance with the requirements in Implementing Equipment Afodifications. assure that specified acceptable fuel design paragraph (e) of General Design (1) For each light water-cooled nuclear limits and design conditiona of the reactor Criterion 17 of Appendix A of this part. power plant licensed to operate on or coclant pressure boundary are not exceeded.

(b) l. imitation of Scope. Paragraphs (c) before [ insert the effective date of this one of these circuits shall be designed to be  ;

and (d) of this section do not apply to amendment l the licensee shall. within available within a few seconda followiryt a '

those plants licensed to operate prior to 180 days of the notification provided in I "-*f-co I*n' *ccident t assure that core  ;

[ insert the effective date of this accordance with paragraph (c)(2) of this "',*i"*',,"'M;'n N d ther vital 8

• amendment)if the capability to section, submit to the Director of the f,;,

withstand station blackot.t was (d) Provisions shall be included to Office of Nuclear Reactor Regulation a minimize the probability of losing electric considered in the operating bcense schedule for implementing any power from any of the remaining supplies as proceeding and a specified duration was equipment and procedure modifications a result of. or coincident with, the loss of accepted as the licensing basis for the necessary to meet the requirements of power generated by the nuclear power unit, facility. General Design Criterion 17 of Appendix the loss of power from the transmission (c) Implementation--Determinatibn of A of this part.This submittalmust network, or the loss of power from the onsite Station BlocAoct Duration. (1) For each include an explanation of the schedule electric power supplies.

light-water-cooled nuclear power plant and a justification if the schedule does I'l D* "**' ' **'* ""d * ***CI*I'd licensed to operate on or before [ insert not provide for completion of the c lant.C ntr I.and protection systems. -

the effective date of this amendment l, .

the licensee shall submit to the Director modifications within two years of the NcInt ap$ an p btlity i a sure '

notification provided in accordance with that the core is cooled and containment of the Office of Nuclear Reactor paragraph (c)(2) of this section.

Regulation by [ insert a date 270 days integrity is maintained in the event of a (2) The licensee and the NRC staff station blackout (as defined in i 50.21 for se after the effective date of this shall mutually agree upon a final specified duration. ne following factors amendment): schedule for implementing modifications shall be considered in specifying the station (i) A determination of the maximum necessary to comply with the blackout duration:(1) the redundancy of the duration for which the plant as currently requirements of Criterion 17. noite emergency AC power sources. (2) the designed is able to maintain core reliability of the onsite emergency AC power cooling and containment integrity in the 4.In Appendix A. General Design sources. (3) the expected frequency of loss of event of a station blackout as defined in Criterion 17 is revised to read as offsite power, and (4) the probable time i 50.2; follows. needed to restore offsite power.

(ii) A description of the procedures Appendix A--General Design Criteria Dated at Washington, DC, this 17th day that have been established for station for Nuclear Power Plants o ich 1986.

blackout events for the duration , , , , , For the Nuclear Regulatory Commission.

determined in paragraph (c)(1)(i) of this samuel I. Chilk.

section and for recovery therefrom; 11. Protection by Multiple fission Product Secretaryofthe Commission.

(iii) An identification of the factor (s) Barners that limit the capability of the plant to , , , , , Backfit Analysis cope with a station blackout for a longer Criterion 17-Electric power systems. (a) Analysis andDetermination That the time than that determined in paragraph An onsite electric power system and an ProposedRulemaking To Amend 10 CFR (c)(1)(i)of this section; offsite electric power system shall be (iv) A proposed station blackout provided to permit functioning of structures. 50 Concerning Station BlocAout duration to be used in determining systems, and components important to safety. Complies With the BocAfit Rule 10 CFR compliance with paragraph (e) of The safety function for each sy stem General Design Criterion 17 of Appendix c ink) s* hat be to provid sufficient The Commission's existing regulations A of this part. including a justification capacity and capability to assure that (1) establish requirements for the design  !

for the selection based on-- specified acceptable fuel design limits and and testing of onsite and offsite electn,c (A)The redundancy of the onsite design conditions of the reactor coolant power systems (10 CFR Part 50 emergency AC power sources: pressure boundary are not exceeded as a Appendix A. General Design Criteria 17 (B) The reliability of the ensite, resuu 4 anwipated operations! oce=rences and 16). However, as operatmg emergency AC power sources; and 12) the core is cooled and containment experience has accumulated, the

'her tt "" "'  !

(C) The expected frequency of loss of Y concern has arisen regarding the ne n th, l yen fp I J offsite power; and reliability of both the offsite and onsite accidents.

(D) The probable time needed to emergency AC power systems.These (b) The onsite electric power supplies, restore offsite power; and including the batteries. and the onsite electric systems provide power for various (v) An identification of the factors.if distnbution system, shall have sufficient safety systems including reactor core any. that limit the capability of the plant independence. redundancy. and testability to decay heat removal and containment t to meet the requirements of Criterion 17 perform their safety functions assuming a heat removal which are essential for single failum. l for the specified station blackout preserving the integrity of the reactor I duration proposed in the response to (c) Electric power from the transmission core and the containment building. - l paragraph (c)(1)(lv)of this section. 'h * '

[yT,,'Id.it t e sufpliej b wb*p '$y a respectively. In numerous instances

)

(2) After consideration of the independent circuits (not necessarily on emergency diesel generators have failed l information submitted in accordance separate rights of way) designed and located to start and run during tests conducted I with paragraph (c)(1) of this section. the so as to minimize to the extent practical the at operating plants. in addition. a l

l l

~ 1

hM,49 S l y - geg + - Federal Jie Wa6hVol..m.:No.% / PddayiMardi.21,1988i / Proposed h=W 1 -

]; asmsbers:fu L- ' ~ hamres

+_g--t ' "a totuHoes use5mits:-

.< 1he eeuasetad totalcost for p operating reacters to commedy with the -

systems), then the estimated coes damage frequency from station blackout l j,

e'- %,_ -.anstame' seeuishr.se' 'a proposedt =ahdi== ef UE A-44 is. eventa cea increase significantly.  !

l l onessuiescos are estpected.%dsting about $40 raillion. He average cost per De estimated frequency of core regulations do nef requiri4xpEcitly that reactor would be around 3600.000 damage from station blackout events is nuclear power plants be designed to ranging from $200.000 if only a station directly proportional to the frequency of i

<1 withstand the loss of all AC power for blackout assessment and procedures the initiating event. Estimates of station blackout frequencies for this USI were any specified period, and training are necessary, to a l nis issue has been studied by the maxunum of about $4 million if based on actual operational experience. i staff as part of Unresolved Safety Issue substantial modifications are needed. This is assumed to be a realistic including requalification of a diesel indicatorof future performance. An l (USI) A-44 " Station Blackout." Both deterministic and probabilistic analyses generator. argument can be made that the future l were performed to determine the timing The overall value-impact ratio. not performance will be better than the past.

and consequences of various accident including accident avoidance costs, is ' For example, when problems with the 4 sequences and to identify the dominant about 2.000 person-rems averted per offsite power grid arise, they are fixed, factors affecting the hhad of core million dollars. If cost savings to and therefore, grid reliability should d

raeli acridents from station blackout. industry from accident avoidance (i.e, improve. On the other hand, grid power l failures may become more frequent 9 These studies indicate that station ciennup and repair of onsite damages P blackout can be a significant contributor and replacement power) were included. because fewer plants are being built.

to the overall plant risk. Consequently, the overall value-impact ratio would and more power is being transmitted

=

the Conomission is proposing to amend improve significantly to about 8.000 between regions, thus placing greater its regulations to require that plants be person-rems averted per million dollars. stress on transmission lines.

5 capable of withstanding a totalloss of his analysis supports a A number of foreign countries, j AC power for a specified duration and determination that a substantial including France. Britain. Sweden. -

W to maintam reactor core cooling during increase in the protection of the public Germany and Belgium, have taken steps that period. health and safety will be derived from to reduce the risk from station blackout

) An analysis of the benefits and costs the backfit in the proposed station events.These steps include adding  ;

- of implementing the proposed station . blackout rule, and that the backfit is design festures to enhance the blackout rule is presented in NUREG- justified in view of the direct and capability of the plant to cope with a i 1t00, Draft Report For Comment, indirect costs ofimplementing the station blackout for a substantial period '

" Regulatory Analysis for the Resolution proposed rule. of time, and/or adding redundant and

. of Unresolved Safety lasue A-44. Station ne quantitative value-impact diverre emergency AC power sources.

• Blackout **

• The benefit from analysis discussed above was one of the The factors discussed above support implementing the proposed rule is a factors considered in evaluating the the determination that additional i reduction in the frequency of core melt proposed rule, but other factors also defense in depth provided by the ability l: per reactor-yeac due to station blackout played a part in the decision. making of a plant to cope with station blackout and the associated risk of offsite process. Probabilistic risk assessment for a specific duration is warranted. The radioactive releases. ne risk reduction (PRA) studies performed for this USI. as Commission has considered how this

. for 67 operating reactors is estimated to well as some plant-specific PRAs. have backfit should be prioritized and li be 80.000 person-rems.' shown that station blackout can be a scheduled in light of other regulatory

i The cost for ficensees to comply with significant contributor to core melt activities ongoing at verating nuclear the proposed backfit would vary frequency, and, with consideration of power plants. Stati ,n b.ackout warrants depending on the existing capability of containment failure, station blackout a high priorit3 rnxing based on both its g

each plant to cope with a station events can represent an important status as an " unresolved safety issue" blackout, as well as the specified station contributor to reactor risk. In general. and the results and conclusions reached j blackout duration for that plant. The active contaimnant systems required for in resolving this issue. As noted in the costs would be primarily for licensees to heat removal, pressure suppression, and implementation section of the proposed j develop procedures, to improve diesel radioactivity removal from the rule (150.63(d)). the schedule for j generator reliability if the reliability containment atmosphere following an equipment modification (if needed to falls below certain levels, and to retmfit accident are unavailable during a meet the requirements of the proposed plants with additional costponents or station blackout %erefore, the offsite rule) shall be mutually agreed upon by systems, as neassary, to meet the risk is higher from a core melt resulting the licensee and NRC. Modifications proposed requirersents.: from station blackout than it is from that cannot be scheduled for completion )

q many other accidant scenarios. withirt two years after NRC accepts the j

>

• or n sounsc-tios wu s=.d a p.btic Although there are licensing licensee's specified station blackout j comment i. ).nu.ry asses c., g m.n, ort m requirements for guidance directed at duration must be justified by the l avs44 ble h iup.cnon .nd ca, yins for a w . ih* providing reliable offsite and onsite AC licensee.  !

y) NRC Public Document Room.1r17 ll Street. NW.,

t wuMnston. DC sness. Free omnie copies of Dren power, experience has shown that there Analysis of 50.109(c) Factore

{ NURECHiss unay be obtained by writins to the are practical limitations in ensuring the l PuMicabo. Smicas Secuen. Roose P-20A. reliability of offsite and onsite 1. Statement of the specific objectives  !

"[,",,i",NN,',"*,','"E",y c'omm 'Oo"' emergency AC power systems. Potential that the proposed backfit is designed to c

wouns,an.oc nossa. vulnerabilities to common cause failures ac!deve.

• Th. ni 4 ,.cs en.ly i. in Nunsc-nos wu associated with design, operational and ne NRC staff has completed a review a bued om N J nahmtion for a inimi of er environmental factors can affect AC and evaluation of information developed ructana Ahhoueh there m curr.edy b.us ico power system reliability. For example, if over the past 5 years on Unresolved v.1 r ua in potential common cause failures of Safety Issue (USI) A-44. Station opmansg,aeam,.

m , , , , , qegg,e emergency diesel generators exist (e.g., blackout. As a result of these efforts, the b--.- .iam ina in the member of erm' ins i plants. , in service-water or DC power support NRC le proposing to amend 10 CFR Part j 4

e

o l Federal Register /'Vol 31. No. 55 / Priday March 21. 1986 / Proposed Rules 9835

• \

50,by the hadweim of new $ 58LSS. trainlag to cope with and recover froan a For 87 operatiegeeacters the  ;

" Station Blackout." and an adational' station blackout. estimated total cost for NRC review of )

parassapbtoGeneral Daews Criterian 3. potential change in the risk to the industry submittals requtred by the 17." Electric Passar Systessa"la - public fana the acddental off-site proposed rule is $500.000 (based on an Appendix A. release of radioactive material. estimated average of 120 person. hours

%e objective of the proposed rule is Based on an analysis of potential per reactor; see Table 8 in NUREG-to redum the risk of severe accidents consequences presented in Section 4 of 1109).

associated with station blackout by NUREG-1109. if the proposed rule were 8.The potential impact of differences making station blackout a relatively impicnented, the estimated total risk in facility type, design or age on the srnall contributor to total core melt reduction to the public from 67 operstm.g relevancy and practicality of the frequency. Specifically, the proposed reactors is 80.000 person-rem. proposed backfit.

rule woeld require all light-water-cooled 4. potentialimpact on radiological g g g g;,, g gg meclear power piacts to be able to cope exposure of facility employees.

pressurized water reactors and boiling with a station blackout for a specified For 67 operating reactors the water reactors. liowever, in determining uranoa em to haw pmcedums and e t k1 mdu

, ,,, j ,,p,eu r sulting from the specific minimim station blackout traan;ng for such an event. A draft coping capability for each plant.

Regulatory Guide to be issued along reduced cm melt fmqmcies and differences in plant design. (e.g., number associated post. accident cleanup an with the proposed rule, would pmvide d em mM M h an acceptable method to determine the ec "

, N ase reliability of the offsite and onsite station blackout duration for each plant. . emergency AC power systems could The duration would be determined for in pa o" '

result in different coping capabilities.

each plant based on a comparison of the g e d and ma t im I th d ruj For example, plants with an already low individual plant design with factors that risk from station blackout would be Eq i ent dit$on d modbcations aw a se maa contemplated do not require work in required to withstand a station blackout "

ca on td of me meh and around the reactor coolant system for a relatively short period of time: and resulting frosa station blackout. These few,if any hardware backfits would be and therefore would not be expected to factors are:(1) Abe redundancy of onsite required as a result of the proposed rule.

result in significant radiation exposure emergency AC power sources. (2) the plants with cunently higher risk from reliability of oasite emergency AC (Table 8 in NUREG-1109). station blackout would be required to

5. Installation and continuing costs ,

power sources. (3) the frequency of loss associated with the backfit. including withstand somewhat longer d.setion of offaite power and (4) the probable the cost of facility downtime or the cost blackouts: and, depending on ' heir time needed to restore offsite power. of construction delay. existing capability, may need awe

2. General description of the activity For 67 operating reactors, the total modifications to achieve the long.r that would be required by the licensee estimated cost for assessing the station station blackout capability, or applicant in order to complete the blackout coping capability, procedures 9. Whether the proposed backfit is backfiL and training, installation of hardware interim or final and ifinterim, the in order to assure that each nuclear - backfits (if necessary). plant downtime. justification for imposing the proposed power plant is able to withstand and and operation and maintenance is $40 backfit on an interim basis.

recover freus a station blackout for a million. (See Tables 6 and 8 in NUREG- ne proposed rule is a final resolution specified mm-um duration, licensees 1109). of USI A-44;it is not an interim would be required to assess their plants

• 6. We potential safety impact of measure.

capability to withstand and recover changes in plant or operational from a station blackout.This evaluation complexity, including the relatioriship to Int Doc. 8&rc84 nled 3-20-86,8A5 am]

would inclnde: proposed and existing regulatory 8'N C" '5"

• Verifying the adequacy of station requirements. _ _ _ _

battery power, condensate storage tank The proposed rule for plants to be capacity, and plant / instrument air for able to cope with a station blackout PARTMENT OF TRANSPORTA N the station blackout duration. should not add to plant or operational

• Verifying adequate reactor coolant pump complexity.He relationship between Fed I Aviation Administra seal integrity for the station blackout the proposed station blackout rule and duration so that sealleakage due to lack of proposed and existing regulatory 14 CF art 71 seal cooling would not result in a sufficient requirements is discussed in Section 4.2 primary system coolant inventory reduction of NUREG-1109.This discussion (AJrspace het No. 86-A -11 to lose the ab'.lity to cool the cere. includes the following NRC generic

• Verifying operability of equipment programs: Proposed A of Transition needed to operate during a station

• Generic Issue B-56 " Proposed Area; Dallas /F W TX blackout for environmental conditions Actions for Enhancing Reliability of Correction associated with totalloss of AC power Diesel Generators at Operating Plants."

(i.e loss of heating, ventilation and air . Generic Issue 23." Reactor Coolant In FR Doc. 39. ginning on page conditioning). Pump Seal Failures." 7950, in the iss of Frid . March 7.

Depending on the plant's existing

• USI A-45. " Shutdown Decay lleat 1986, make t following c ections:

, capability to cope with a station Removal Requirements." 1. On pa 7951, third colu thirty.

blackout. licensees may or may not need

• Generic lasue A-30. " Adequacy of first line, the end insert "to titude to backfit hardware modifications (e.g.. Safety Related DC Power Supply." 33*13' N ".

adding battery capacity) to comply with 7.He estimated resource burrien on 2. same page. third column. irty.

the proposed rule.(See item a for the NRC associated with the proposed four line, before "thence" insert addi,tional discussion.) Licensees would backfit and the availability of such al gitude97*39'30" W ".

be required to have procedures and resources. coes nes * =

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