ML20003A267
| ML20003A267 | |
| Person / Time | |
|---|---|
| Site: | Maine Yankee |
| Issue date: | 01/30/1981 |
| From: | Garrity J Maine Yankee |
| To: | Eisenhut D Office of Nuclear Reactor Regulation |
| References | |
| RTR-NUREG-0737, RTR-NUREG-737, TASK-1.C.1, TASK-TM FMY-81-11, JHG-81-50, NUDOCS 8102030294 | |
| Download: ML20003A267 (4) | |
Text
.
h RIAIRE "%09ARHEE Atom /C POWER COMPARS
- Box 450, aro 2
@!:L"lii/
January 30, 1981 Wiseasset, Maine 04578 4
2-Q.1 JHG-81-50 EMY-81-ll Unites States Nuclear Regulatory Cmmission Washington, D. C.
20555 Attention: Darrell G. Eisenhut, Director Division of Licensing
References:
(a) License No. DPR-36 (Docket No. 50-309)
(b) USNRC Latter, D. G. Eisenhut to All Licensees of Operating Plants, dated October 31, 1980 (c) MYAPC Iatter (WMY 80-162) to USNRC, dated December 15, 1980
Subject:
Post DfI Requireents - Guidance for Evaluation and Develognent of Procedures for Transients and Accidents.
Dear Sir:
his letter describes the program to be undertaken by Maine Yankee to respond to " Guidance for Evaluation and Developnent of Procedures for Transients and Accidents", Item ICl of NUREG 0737. H e nnst recent revision l
to this guidance was transmitted to Maine Yankee via ref. (b), which also requested, pursuant to 10 CFR 50.54(f), information relating to Maine Yankee's cmmitment with respect to the impleentation date asecciated with this task.
l Maine Yankee responded via ref. (c), in which a cmmitment was made to have l
revised procedures available end te have ccmpleted procedure impleentation l
and personnel training by the first retualing outage after Jan.1,1982, and to subnit a progran description by Jan. 31, 1981.
Maine Yankee has already completed a major upgrade of the emergency operating procedures existing at the time of the DfI accident. h is previous ulgrade involved intensive investigation of small break LOCA phenomena, generation of small break IDCA guidelines for the CE Qener's Group by Combustion Engineering, approval of these guidelines by HEC, and implenentation of the guidelines in Maine Yankee's procedures.
In addition, for non LOCA transients and accidents, Maine Yankee participated in the CE l
Gener's Group review of transients and accidents, developnent of guidelines for transients, accidents, and inadequate core cooling, and factored the results of these effexs into emergency operating procedures. Procedure
[; revision considered plant specific information and scenarios leading to core g
melt.,
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, he mergency operating and casualty procedures now in effect were produced by a task tean assenbled to revise pre-DfI procedures both to 1l-
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United States Nuclear Regulatory Cecmission January 30, 1981 Attn: Mr. Darrell G. Eisenhut Page Tao incorporate all relevant new Tehenical information and NRC staff guiciance concerning operating strategiaa aM plant response and to improve the effectiveness of procedures from a human factors point of view. The task team consisted of senior oersomel drawn frcn the Maine Yankee operating organization and the Nuclear Services Division. Permanent members of this task tem were the Maine Yankee Director of Operational Support (chair), the Maine Yankee Assistant Operations Department Head, the Nuclear Services Division Manager of SR Transient and Accident Analysis, and a Nuclear Services Division Plant Engineeriq Deparcuent Principal Engineer. Additional tectnical expertise was dran upon as needed.
In the task tem core alone was vested collectively nearly half a century of experience in design, analysis, and operation of nuclear power plants including Maine Yankee, other WR's, a BWR, Navy nuclear propulsion plants, and large liquid metal cooled fast breeders.
The approach of upgrading procedures through a task team of highly qualified senior persomel will be maintained through the progra described below.
Su: mary of Procra Maine Yankee will furthat upgrade its casualty and emergency operating procedures through a progra consisting of two major tasks which will run essentially in parallel. Each task involves additional analysis and evaluation of the Maine Yankee p1mt specific design (NSSS and BOP) to better characterize plant response to abnormal conditions and formulation of improved i
strategies for use by the operator in controlling such conditions. Each task explicitly takes into account multiple-failures and operator errors.
TASK 1 Task 1 involves upgrading Maine Yankee's existing casualty and emerg9nc operating procedures by application of the critigq} safety functionstl)yand l
safety function and protection sequence analysisW concepts.
Task 1 will thus result in more explicit consideration of primary and alternative methods of achieving, re-establishing, or maintaining critical l
safety functions within the context of existing casualty and emergency operating procedures.
t i
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1 W. M. Guinn, Program Manager, W. R. Corcoran, N.J. Porter, J.F. 01urch, M.T. Cross, The Critical Safety Functions and Plant Operations.
.C-E Publicction TIS-6743, Presented at International Conference on Current l
Nuclear Power Safety Issues, Sponsored by IAEA, October 20-24, 1980.
2 R. A. Fortney, J. T. Snedeker, J. E. Howard, W. W. Larson, Safety Function and Protection Sequence Analysis. Presented at American Nuclear society Winter Meeting, November 11-16, 1973.
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Y United States Nuclear Regulatory Comnission January 30, 1981 Attn: Darrell G. Eisenhut Page "hree Task 2 Task 2 involves application of probabilistic risk assessment techniques to the Maine Yankee design to identify significant accident initiators and sequences.
His task win ephasize characterization of plant design and response by use of event tree and taule fre techniques rather than detailed sequence quantification or consequence calculation.
l Be results of Task 2 win be used to assure that significant crediMe events and sequences are covered in plant casualty and mergency procedures.
A consultant will likely be retained to assist in this task.
Schedule i
Task 1 will be completed, and the results reflected in improved casualty and emergency operating procedures, by the end of the 1%2 refueling outage.
1 Task 2 will be completed and the results reflected in further improvements to l
casualty and mergency procedures by the end of 1%3.
l l
Additional Information he Maine Yankee Atomic Power Station utilizes a Combustion Engineering NSSS with several design features unique mong CE plants. For ex m ple, the Maine-Yankee design employs three' loops, each with one U tube steam generator, one reactor coolant punp, one passive ECC accunulator, and two loop isolation valves in contrast to the usual 2 x 4 CE design. As another example, the Maine Yankee ECCS design utilizes high head high pressure safety injection punps which can deliver flow to the reactor coolant system when the tystem is at and above normal operating pressure (2250 psia). Maine Yankee of course exhibits the usual taiqueness in BOP design and station layout.
Maine Yankee's inhouse analytical capability, and the usage of this l
capability, are also somewhat unique in that Maine Yankee performs essentiany an necessary licensing, safety, and engineering analysis inhouse without NSSS vendor assistance.
Maine Yankee's unique NSSS design, together with the disparity between BOP design and layouts of CE, and indeed a u nuclear plants, render more difficult the developnent of best estimates of plant behavior under abnormal conditions which apply to Maine Yankee as weH as the other CE plants. Historically, Maine Yankee has had to very carefully review generic bounding analyses to assure applicability to Maine Yankee. The verification of applicability of best estimate generic analyses, in which large conservative margins to accanodate detailed differences in design are tmdesirable, appears to require even more effort than in the case of very conservative licensing analyses.
Bis verification effort lags generic analysis, so it creates both an additional workload and a delay in application of the results, part.icularly if rework is found to be necessary.
United Statcs Nuclear Regulatory Comnission January 30, 1981 Att.1: Darrell G. Eisenhut Page Four Recognizing both the uniqueness of the Maine Yankee design and the available inhouse analytical capability, Maine Yankee will proceed directly to production of improved casualty and emergency cperating procedures developed specifically for the Maine Yankee design.
In this way, Maine Yankee will achieve several objectives:
w? proved procedures which consider multiple failures and operator errors Im l be available and impleented with a minimun of delay.
The improved procedures will be based upon and derived directly from consideration of the Maine Yankee design, ie, they will be plant specific.
Nch of the work will be performed inhouse by personnel who are very faniliar with the Maine Yankee design and the unit's operating history.
All details relevant to the methods, assumptions, and results will be available for future reference.
The end product will be the result of the combined efforts of the engineering and operations staffs, and will reflect the synergistic effects of such a multidisciplined approach.
Maine Yankee personnel involved in the effort will be the primary beneficiaries of the knowledge to be gained by performance of the necessary work.
Docunentation of prc;Iam output can be specified with application to training prograns in mind.
With respect to Task 2, Maine Yankee will obtain a plant specific characterization of the Maine Yankee design and exprience in plant specific application of PRA techniques which will be applicable to l
future NREP and licensing work.
We trust the information contained herein is adequate; however, if further clarification is necessary, do not hesitate to contact us.
Very truly yours, MAINE YAM (EE ATRfIC POWER 0@fPANY
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John H. G u ity, Director Nuclear Engineering & Licensing JHG/bjp Enclosure l
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