ML073410249

Transmittal of Revision 1 to Regulatory Guide 1.97, a Clearer Basis for Development Initial Response

ML073410249
Person / Time
Site:	Watts Bar
Issue date:	03/07/1978
From:	Varga S Office of Nuclear Reactor Regulation
To:	Niav Hughes Tennessee Valley Authority
References
Download: ML073410249 (6)

Text

SRN E UNITED STATES NUCLEAR REGULATORY COMMISSION

- .WASHINGTON, D. C. 20555 MAR 07 1978 Docket Nos.

Tennessee Valley Authority ATTN: Mr. N. B. Hughes Manager of Power 830 Power Building Chattanooga, Tennessee 37401 Gentlemen:

SUBJECT:

REVISION 1 TO REGULATORY GUIDE 1.97 As a result of recent discussions and correspondence concerning Revision 1 to Regulatory Guide 1.97, the staff has developed more specific guidance to assist you in responding to our letter dated October 18, 1977.

This enclosed guidance provides a clearer basis for the development of your initial response. Its issuance, in our opinion, precludes the need for additional meetings to discuss the guide. Please let us know, however, if you have further questions or if you feel that further meetings are necessary.

In order to continue the effort involved in implementation of Regulatory Guide 1.97, we require that you submit the information described in our October 18, 1977 letter by May 1, 1978.

Sincerely,

'Steven A.V'gajf ef Light Water Reactors Branch 4 Division of Project Management Enclosure.:

As stated CcS:

Listed on page 2

'K

Tennessee Valley Authority MAR 0 7 1978.

CCS:

Herbert S. Sanger, Jr. Esq.

General Counsel Tennessee Valley Authority 400 Commnerce Avenue E liB 33 Knoxville, Tennessee 37902 Mr. E. G. Beasley Tennessee Valley Authority W9C165, 400 Cormmerce Avenue Knoxville, Tennessee 37902 Mr. Wesley Byrd, Project Manager Tennessee Valley Authority 303 Power Building Chattanooga, Tennessee 37401

1. The analysis described in position C.1 and C.2 should include the followina:

a.. For each accident analyzed in Chapter 15 of the PSAR, describe

ýhow the proposed accident monitoring instrumentation will meet each provision of Positions C.l.a through C.l.f. Instru-mentation provided in response to Position C.l.f shall include appropriate monitors-of radioactive release rates through identifiable release points.

b. Provide a specific reference and/or detailed description of how each instrument or group of instruments will satisfy the provisions of Positions C.4 through C.17. A general statement that a Position will be met is not sufficient.

2. Implementation of Position C.3 of Regulatory Guide 1.97 These guidelines provide a framework for the specific selection of instruments for worst-case conditions. These refer to situations where system performance is degraded such that coolant and containment pressures, and radiation levels in containment and in releases, greatly exceed values established by analyses of the postulated accidents listed in Chapter 15.

These worst case conditions may stem from several types of causes which. have been identified in risk assessments (see WASH-1400 for one assessment of dominant event sequences in two reactors). The four measurements required by Position C.3 are considered to provide

adequate informO11. to th* operator to meet Position C.l.f of the guide for accidert situaU.ions covered by C.3 ýsee. General below).

Additional types of measurements may, however. be appropriate where, for a specific reactor design, the staff has-identified accident sequences whhere operator a,.,iareness of the situations considered in Position C.3 ,would not otherwise be likely.

Three of the fo:ir measurements called for in Position C.3 are specific; the fourth is nat (monitoring radioactivity release rates through identifiable release points). Listed below is supplemental guidance lor C.3.d.

a. General: The. intent is to monitor rates of releases for the worst-case conditions discussed above. The intent is to provide an assessment canoability that. will satisfy Objective 6 of the Discussion ('"allow for early indication of the need to initiate action necessarv to protect the public and' for an estimate of the magnitude of the impending event").

b.. Identifiable release points: Identifiable release points should include:'

(1) For Fi! in GW B.s (a) Auxiliary building ventilation exhausts from areas where, (i) ECCS enuipment is housed and (ii) Containment penetrations are located.

iOther release points may be determined to be imuportant as a result of the analyses perrfo- rfrd in conformance with Position C.l. This matter is to be addressed in connection withPhase II reviews (implementation of other Provisions of F'eoulatory Guide 1.97, the scope of --hich.for oreating reactors ,-ill be determined, on a case-by-.case basis)

(b) Containment purge line exhaust-downstream of filters, if any.

(c) Annulus exhaust downstream of filters; if any.

(2) In addition, for BWRs (a) Air ejector exhausts imme'diately downstream of the air ejectors.

c. Release Rates: The instrumentation need not have the capability to identify the rate of release of specific isotopes; rather the objective should be to have the capability to estimate the order of magnitude of the releases. In addition, these instruments will have the capability to estimate the rate of release of I vs. noble gas activity.

Tables VII 1-2, 1-3 and 1-4 of WASH-1400 are acceptable as a basis for establishing the initial airborne inventory of isotopes within the containment. The CORRAL Code analyses of WASH-1400 may be used to estimate the behavior of the activity within the containment.

This information can be used to estimate the rates and magnitudeof releases to the release points considered above [worst case scenarios that result in an immediate release and for which instrumentation is not practical or would not provide useful information (e.g., steam explosions) need not be considered]. An alternate approach would be. to determine the instrument requirements necessary to monitor releases that contain activityconcentrations equivalent to that in the undiluted containment atmosphere described above. In. all cases, the instrument proposed must be capable of measuring activity release rates between the upper limit of the normally installed instrumentation and the maximum release rate identified using one of the procedure described above.

3. The..schedule for iimplementation of Regulatory Guide 1.97 includes development of the identification of the characteristics including location, range, environment, etc., of instrumentation to follow the course of an accident. In its assessment of the applicants proposal the staff will consider the availability of the equipment described. However, the staff, recognizes that the schedule for installation of the equipment must include an allowance for development of equipment that is not currently commercially available, if equipment that is presently commercially available is not acceptable.