ML19207C164

Forwards Responses to Reactor Sys & Radiological Assessment Branch Questions in NRC 790807 Ltr to Hg Parris.Responses Will Be Incorporated in FSAR Amend 62

ML19207C164
Person / Time
Site:	Sequoyah
Issue date:	08/31/1979
From:	Mills L TENNESSEE VALLEY AUTHORITY
To:	Rubenstein L Office of Nuclear Reactor Regulation
References
NUDOCS 7909070315
Download: ML19207C164 (4)

Text

a. ,a TENNESSEE VALLEY AUTHORITY CH ATTA NOOO A. TENN ESSEE 37401 400 Chestnut Street Tower II August 31, 1979 Director of Nuclear Reactor Regulation Attention: Mr. L. S. Rubenstein, Acting Chief Light Water Reactors Branch Nc. 4 Division of Project Management U.S. Nuclear Regulatory Cocsission Washington, DC 20555

Dear Mr. Rubenstein:

In the Matter of the Application of ) Docket Nos. 50-327 Tennessee Valley Authority ) 50-328 Enciosed are responses to the questions (Reactor Systems Branch and Radiological Assessment Branch) transmitted by your letter to H. G.

Parris dated August 7, 1979. These responses will be incorporated in Amendment 62 of the Sequoyah Nuclear Plant Final Safety Analysis Report as questions 15.16B, 9.41, and 12.16.

Very truly ycurs, TENNESSEE VALLEY AUTHORITY

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ENCLOSURE RESPONSE TO L. S. RUBENSTEIN'S LETTER TO H. G. PARRIS DATED AUGUST 8, 1979 Item 1 Reactor Systems Branch - (212.0) 15.16B Confirm the points discussed in the telephone call of July 24, 1979, with respect to operator actions related to the detection of a boron dilution event at the time of reactor shutdown. The points discussed which require confirmation are the following:

, (a) Within what time interval af ter shutdown will the cperator make his first check of the setting of the High Flux at Shutdown alarm?

(b) Within what margin from background level will the operator maintain this High Flux at Shutdown alarm based on his first check and at eacn subsequent check?

Response

(a) In accordance with Sequoyah Nuclear Plant Units 1 & 2 Surveillance Instruction - 603 - (High Flux Adj ustment After Shutdown) - The high flux at shutdown alarm setting will be adjusted once the count rates on the source range Nuclear Instrumentation System are below the P-6 interlock setpoin.. For the most limiting case shown in response 15.16A, this occurs 15 minutes after reactor shutdown. Thus the assumption used in the analysis for response 15.16A, where the operator checks and adjusts High Flux at Shutdown Alarm setpoint at 21 minutes, is conservative.

(b) As shown in Surveillance Instruction 603, the alarm setpoint must be sut or verified to be within one-half decade above the shutdown count rate at the first check and after each subsequent check. After the first check, the subsequent checks will be made every two hours or any time the setpoint exceeds the shutdown count rate by tuo decades until the flux level has stabilized.

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Item 2 Reactor Systems Branch - (231.0) 9.41 During a recent refueling outage at a W plant (Salem 1), Strap damage was observed on a number of fuel spacer grids. It as not known whether the damage occurred during the initial core loading or during the refueling withdrawal. Whc. assurances can you provide that the same type of grid damage will not be experienced at Diablo Canyon 1 and 27

Response

Evidence from other 17x17 refuelings. indicates that the potential for fuel damage can be minimized or eliminated by exercising care during the handling operations. For practical and commercial reasons alone, we therefore intend to exercise due caution to ensure our fuel handling operations take advantage of all precautions that may protect the fuels integrity. Tliese will include proper training and use of qualified operators, confirmation of proper functioning and alignment of the fuel handling and transfer equipment and implementation of appropriate fuel handling precautions and recom=endations provided by }i based upon their assessment of the Salen experience.

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Item 3 RADIOLG01 CAL ASSESSMENT BRANCH - (331.1) 12.16' Describe precautions taken to prevent inadvertent employee access during fuel transfer to the very high radiation areas in the vicinity of the fuel transfer tube. If there is suf-ficient permanent shielding to ensure acceptable radiation levels in adjacent potentially occupied areas, provide relevant plan and elevation drawings.

Response

Accessible areas near the fuel transfer tube are protected with permanent shielding to limit dose rates to 5 mrem /hr or less during fuel transfer.

In the emergency passageway under the fuel transfer tube, the peIcanent shielding may allow dose rates as high as 210 mrem /hr during fuel transfer.

This area is shown on Figure 12.1-9, and the shielding is described in section 12.1.2. The fuel transfer tube shielding at Sequoyah is similar to that at Watts Bar Nuclear Plant. (See Watts bar FSAR Figure ]2.3-]2).

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