ML19269C036
| ML19269C036 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 01/09/1979 |
| From: | Deyoung R Office of Nuclear Reactor Regulation |
| To: | Fridman Y AFFILIATION NOT ASSIGNED |
| Shared Package | |
| ML19269C037 | List: |
| References | |
| NUDOCS 7901190229 | |
| Download: ML19269C036 (7) | |
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. e s. Yury Fri m an THIS DOCUMENT CONTAINS 1237 '. orth Curson Avenue, =s POOR QUALITY PAGES Les : ;el es, Cc'ifornia 900?5
Dear Mr. Fricnia:
I am.<ri ting in ans..er to your l ettar of "cVe'be-16,1973, i n
..hich you excross concern -: cut "hazares cenrected with cre-ation
- ' ;:::ar ol ants and sa faty aasures t a t are nic ;3ary te p e. :-ot
- 'c s 3 ;a:1res".
You ' ave c:- antad on the E ergency Car? Cooling Syssam (ECCS),
and in particular, the San Onofre ECCS "inadecuacy" and the Bro.ns
-arry ECCS " f a il ure".
The ECCS in the San Cnofre pl ant is desi; red to meet the single failure criterion recuired by the SC regulations.
This critarian recuires tha t all the cor;onents reeded for :ceration of the ECCS should have suitable redur.dancy, or duolicaticn, such
-h a t a fail ure of one cc conant.,ill r.ot ;revent the syste.n f e c.a 2rfor:aing 1:s d2 sign functicn.
To further assure the reliable M)eration of the ECCS, periodic testing is performed at specified time intarv31s.
For pr3ctical reascas, these tests consist of tasting the indiviibal sys tem cc7ponents. This method permits verification of tne ccerability of che system without shutting down the pl ant for extedded periods of time.
As a result of testing individual components of the San Cncfre ECCS, some of these components were found to be cef?ctive or inocerable.
Mcwever, because of the redundancy or duplication built into the system, none of these failures could by itsel f inc3cacitate the EC CS.
These periodic tests are required by the plant's license for the specific purpose of detecting any defective ca.rponent cuickly so it may be fixed or replaced.
It is incorrect, therefcr?,
to conclude that the failures occurring during the ECC5 tasting in the San Onofre clant uculd cause the ICCS to fail in the event of a postulated accident.
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"r. vury ricman 2
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';-c;-dir.c ycur c:r ent aq t's Er;<.n s Fe rry ECCS " f 311.re", a function of the ICCS i s to maintain adecu3te Cure coolinc 3fter in sccident such as a loss of coolant accident (~_2:A).
ibis accident can occur as a result of a pice break cr a failvre of Ot.ner cccoonents Wnich constitute the reactor cool ant system crassure bcundary. Durirg the Erowns Ferry fire in 1975 no such
- .ent teck pl ace anc the ECCS rev ar.3s r3quirac to 0:er3t?.
"cu 13ve al so crment2d cn the r3diaticn rel ated to r.uclear Oc<.er pl ant operation.
You are correct tha t each parson in the U.S. i s exposed to abcut 150 millrels/ year fr:n natural background radia tion.
Or ise 2.3rc7e, 53cr carsen is ex esec :: 3r uc i i:nal 100 milli-t
' "C. year f'01 7-r 2;'s u s ed by 10C lo rs 3 Gd C 3 n!i s! 5 for di39"OstiC eM t12 m a nic : 2rxs35.
H: 3v 3r, the 3. arege imsure to radia-tien as a recti t of the use of nuclear pm.ar is 1 ass than 0.1 milli-ra's/ year to 3ach individual in the U.S.
The radiation ex?osure linit, set by the Federal Radiation Ccuncil (that function is now by the Envircraental Protection Agency), is 5000 millies.ms/ year fc c ;acple.50 have to ork in the vicinity of radiation sources, inc one tanth of that, 500 nillirens/ year for any me,ber of the celic. An adciti-:nal limit is inrosed for the cereral cualic and that is a linit cf 170 millirebs/ year average radiat' ion dose to an indivicual in a populution grouo.
The pen,i ssibl e dose for an individual (5000 meea/yr' is "that dose, accunulated over a long period of time or resulting from a single exposure,
..hich, in the light of present knowledge, carries a negligible pecbability of severe somatic or genetic injuries; furthermore, it is such a dose that any effects that ensue more frequently are 1.imited to those of a minor nature that would not be considered unacceptable by the exposed individual and by competent medical authority".
(quoted from International Commission on Radiological Protection Publication 2).
This can be characterized as a "s-dosage", and it is far greater than the value (.01 millireas) you have given.
It is not correct that statistics show unusually high numbers of cases of lung cancer and leukemia in areas surrounding nuclear power plants.
Although there have been some technical presentations to this ef fect (E. J. Sternglass, for example), they have been refuted by careful analyses that reevaluated the statistical evidence of illness along with the measured quantities of radioactivity in the vicinity of the reactor plants.
The levels of radicac tivity resulting from emissions from a nuclear reactor are centrolled to meet regulatory require?ents, and are far belcw natural backgrcund levels, and they are carefully monitored to make sure that no unexpected release is occurring.
- r. Yury Frid,an 3
Y:u ? s :ec that t 2 '?C ti't e 2 009e Sc-io as d 4 sc tic at 31 ini 2:'ac a-ercus croale:,s of nuclear technolcgy.
Eac'1 apalicant for a pernit to construct and a license to 0?erate a auci Ear ;oi er clint 5as ta submi: to t e : 3 S i f a :;<
. 21 y s i s ~, a t : r : that
- iscrices the resign of tne 01 ant anc all tre safd y '33:u as in 3r?at cetail.
The ??C res,orsibility re;3riing thi s s;.cmi:-
sion is described in ;'a arti:.~=a: to thi s l etter.
A sacord attac'rnent describes t"e NRC activities totird insuring safe design of nuclear riants.
In addition to the activities
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Y;u nay have rc:2c in racer: n? s:3:er
.ccounts the success of the Loss of Fluid Test recently carried out at the '.ational Reactor Test Station at Idaho Falls.
This first in a series of tests of the ECCS was entirely successful in reeting its goals.
If rcu have any furti.er cuestions regardinc nuclear cot.er, cl ease feel free to :all ne en (301)492-7207.
Si nc er el y,
/
Richard C. DeYeung, Director Division of Site Safety and Environmental Analysis Office of Nuclear Reactor Regulation
Enclosures:
1.
NRC Responsibility in Regulation of Nuclear Power Plants 2.
Insuring Safe Design of Nuclear Power Plants
ENCLOSURE 1 NRC RE5pCNSIBILITY IN RE3ULATICN OF NUCLEAR :CWER PLANTS The Nuclear Regulatory Commission (NRC), in its review of apolications for licenses to construct and coerate nuclear power plants, is required to consider those measures necessary for the protection of the public's health and safety and the environment and to assure proper regard for antitrust laws and policies.
To carry out its responsibilities, the NRC staff c~onducts detailed reviews of each nuclear power plant application.
In concucting its detailed reviews, the NRC: (1) establishes and reviews qualification and training requirements for all operating personnel; (2) establishes and reviews design criteria; (3) establisnes guidance for, and reviews, the inscection process for the construction and operation of nuclear power plants; (J) establishes acceotance criteria for tne ECCS and other structures, systems and comoonents and reviews all safety-re-lated structures, systems anc cocoonents; (5) monitors the operating history of operating nuclear power plants; (6) establishes recuirements for, and reviews, engineered safety features designed to mitigate the consequences of postulated acci ents; and (7) establishes recuire:nents for, and continuously monitore, the routine releases of radioactive mate-rials from operating nuclear power plants.
While this list is neither comprehensive nor ccmolete, it does serve to illustrate the nature and character of the effort taken by the NRC to ensure tnat appropriate safety and environmental measures are proposed, implemented, and maintained for nuclear power plants.
The entire licensing and regulatory process conducted by the NRC is also subject to acministrative, judicial and legislative review to determine that the NRC does indeed carry out its statutory objectives.
The excell-ent operating history of the civilian nuclear power plants demonstrates the effectiveness of the measures proposed and implemented by the nuclear industry, reviewed and regulated by the NRC and reviewed again by the ACRS, the courts and the Congress.
ENCLCSLRE INSURING SAFE CESIGN OF NUCLEAR PCWER PLANTS The NRC conducts a detailed review of all nuclear pcwer plant applications to insure that comocnents, systems and structures imcortant to safety are designed, fabricated, erected, and tested to quality standards cc rensu-rate with the importance of the safety functions to be performed. These reviews are concucted by scme 50 different technical disciplines organi:ed into 30 secticns in 18 functional branches within the Office of Nuclear Reactor Regulation.
The safety cortion of the application for a nuclear pcwer plant is organized in accordance with a Regulatory Guide, tne Standard Fcreat and Cantent of Safety Analysis Recorts, ahich describes the infccmaticnal needs of the NRC staff in reviewing these applications.
The conduct of the safety review is in accordance with the Stancard Review Plan which describes in some detail how the safety review of LWR applications is acccmplished and whicn criteria are applied in the acceptance of systems, components and structures important to safety.
The criteria used in the review process include NRC Regulations and Regulatory Guices, and incustry standards ccvelopec in conjuncticn with the NRC.
When a nuclear power plant application is submitted, it is first subjected to a preliminary review to determine wnether it contains sufficient in-formation to satisfy the Commission requirements for a detailed review.
If the application is not sufficiently complete, the staff makes specific requests for additional information.
The application is formally dccketed only if it meets certain minimum acceptance criteria.
In addition, when the PSAR is submitted, a substantive review and inspection of the appli-cant's quality assurance program covering design and procurement is :en-ducted. Guides for the preparaticn of the documents, detailing the kind of infonnation needed, have been developed by the staff to aid ccmpanies in preparing acceptable applications.
The staff reviews a. construction permit application to determine if the pub'ic health and safety wiil be fully protected.
If any portion of the application is considered to be inadequate, the staff requests the applicant to make appropriate modifications or provide needed additional information.
The application is reviewed to determine that the plant design is con-sistent with NRC Rules and Regulations.
Design methods and procecures of calculations are examined to establish their validity.
Checks of actual calculations and other procedures of design and analysis are mace by the staff to establish the validity o' the aoplicant's design and to determine that the applicant has conducted his analysis and evaluation in sufficient depth and breadth to support required findings in respect to safety.
2 ENCLCSURE 2-cont'd With regard to accident evaluati'on, tnere are specific design features wnicn must be an integral part of nuclear pcwer plants and wnose cesign basis assumes that there is a release frcm the re'.ctor pressure vessel of the fission products contained in the nuclear cort.
This assumotion is made on a deterministic basis (i.e., no rational mechanism is assumed to be required to obtain this release) so as to impose cxtremely con-servative design conditions on the engineered safety measures wnich are physically incorporated in the power plant to mitigate the consequences of any postulated accident. Mcwever, tnis assumotion implies that there is a complete failure of the safety systems wnicn are specifically de-signed to prevent this release of fission prcducts frcm the reactor core.
This method of designing safety systems to.vitnstand postulated worst case accidents, tnen assuming a failure of these systems and cesigning physically separate backup systems, wnich are diverse in principal, is known as " defense-in-depth."
Scme of the engineered safety systems which are tyoically incorporated into the plant design and which mitigate the consecuences of the postu-lated accident are the primary containment, the secor.dary containment, containment sprays, and charcoal filters.
Prior to licensing a nuclear power plant, the NRC staff is required to demonstrate that the individual doses received by the public at specified distances frcm the facility following the design basis accident (i.e., the fission product release from the reactor pressure vessel) are within the guideline values con-tained in 10 CFR Part 100.
These specified distances are identified as the radius of the exclusion area and the radius of the low population
- ene.
Typical values of these distances are about 1/2 mile for the exclusion area and chout 3 to 5 miles for the low population :ene. These distances vary wito,lant site and are dependent on the power level of a facility, the engineered safety features, and the pertinent meteorological conditions of the plant site.
In addition to the safety review of nuclear power plant applications, the NRC technical staff conducts evaluations of potential safety problems that may apply to many reactors of a given design type.
The detailed review and independent analyses of emergency core cooling system (ECCS) per-formance, anticipated transients without scram (ATWS), and containment pressure are examples of this type of generic study.
The staff also conducts engineering audits of reactor vendors and architect-engineer design calculations and procedures to assure conformance with safety de-sign practice.
The safety review of prebiems of aperating reactors are another means of insuring safe design by applying the findings reachec in these reviews to the licensing process.
. ENCLOSURE 2-ccnt'd The licensing process incluces the consideration of programs proposed by an applicant for a construction permit to verify plant design fea-tures and to confirm design margins.
Cata obtained frcm research and development programs on particular facilities and frca the Ccmmission's safety research program are factored into these licensing reviews.
When the review and evaluation of the application progresses to the point that the staff concludes that acceptable criteria, preliminary design information and financial information are documented in the application, a Safety Evaluation Report is prepared.
This report represents a summary of the review anc evaluation of the application by the s aff relative to tne anticipa ed effect af the prcposed facility on :ne public healtn and safety.
When the construction of the nuclear facility has progressed to the point where final design information and plans for operation are ready, the applicant submits the Final Safety Analysis Report (FSAR) in support of an application for an ocerating license.
The FSAR sets forth the pertinent details on the final design of the facility, including final containment design, design of the nuclear core, and waste handling system.
The FSAR also supplies plans for operation and procedures for coping with emergencies. Again, the staff makes a detailed review of the information. Amendments to the application and reports may be submitted frcm time to time. The staff again prepares a Safety Eval-uation Report (re the operating license) as in the construction permit stage.
Each license for operation of a nuclear reactor contains Technical Specifications, which set forth the particular safety and environmental protection measures to be imposed upon the facility and the conditions of its cperation that are to be met in order to assure protection of the health and safety of the public and of the surrounding environment.
Through its inspection and enforcement program, the NRC maintains sur-veillance over construction and operation of a plant throughout its lifetime to assure compliance with Ccmmission regulations for the pro-tection of public health and safety and the environment.