ML20042C107

Discusses ALARA Investigation Re Replacement of Feedwater Check Valves in Primary Containment.Util Will Retain Exemption to Type C Leak Rate Test Program for Inboard Check Valves & Place Outboard Valves on Leak Test Per App J

ML20042C107
Person / Time
Site:	Vermont Yankee File:NorthStar Vermont Yankee icon.png
Issue date:	03/26/1982
From:	Jackson E VERMONT YANKEE NUCLEAR POWER CORP.
To:	Office of Nuclear Reactor Regulation
References
FVY-82-30, NUDOCS 8203300210
Download: ML20042C107 (3)

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w- -.o VERMONT Y AN KEE NUCLEAR POWER CORPORATION SEVENTY SEVEPl GROVE STREET 2.C.2.1 RUTLAND, VERMONT 05701 FVY 82-30 REPLY TO:

ENGINEERING OFFICE 1671 WORCESTER ROAD FRAMING H AM, M ASSACHUSETTS 01701 TELEPHONE 617 872-8100 1

Marc 6, I g

s E ;h 'l United States Nuclear Regulatory Commission s WCg Washington, D.C. 20555 //, " %) T

(.- %%qg00 70 ~8 Attention: Office of Nuclear Reactor Regulation g  %,fi"^hh Q"hh d

References:

a) License No. DPR-28 (Docket No. 50-271)

VYNPC Letter A

b)  ?

c) (WVY VYNPC Letter (FVY 80-132) 81-148) to USNRC, to USNRC, dated 9/1 dated 10/27/81 /S0; Q i

Subject:

ALARA Investigation Concerning the Replacement of the Feedwater Check Valves in the Primary Containment The purpose of this letter is to inform the NRC of our intentions concerning the installation of check valves in our feedvater system within the primary containment. Vermont Yankee feels that the results of the ALARA investigation conducted during and after this past refueling outage reveals radiation exposures which, by far, exceed the benefits of replacing the existing inboard check valves.

DISCUSSION During the recent refueling outage which commenced on October 16, 1981, Vermont. Yankee replaced one outboard check valve in each of the feedwater lines with a valve capable of passing an Appendix J Leak Test. As stated in Reference (b), our plan was to replace both the inboard and outboard check valves. Prior to the refuel outage, the decision was made to replace only the outboard valves. This decision was based on the estimated man-hours necessary to accomplish the replacement, and the radiation dose levels in our primary containment obtained from the previous refuel outage.

The outboard check valves were replaced which provided us with a log of the man-hours expended to perform various portions of the task.

Also during the refuel outage, radiological surveys of the general area surrounding the inboard feedwater check valves in the primary co'n-tainment were taken. This data, combined with the man-hour total obtained from the replacement of the outboard check valves, was used to calculate j the amount of man-rems involved in repic.cing the inboard feedwater check valves. pOJ O f

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8203300210 820326 PDR ADOCK 05000271 p PM i

U. S. Nuclear Regulatory Commission VERMONT YANKEE NUCLEAR POWER CORPORATION March 26, 1982

.Page 2 Dose Rate to Perform the Replacement The dose rate in the general area of the inboard feedwater check valves in the primary containment this past refuel outage was 80 millirem per hour. This dose rate was used in constructing the following table.

Predicted Exposure for the Replacement of the Inboard Feedwater Check Valves Task Man-hours Man Rems Notes ,

Removing and reinstalling 236 18.9 1 l insulation 1

Removing and reinstalling 88 7.0 1

, adjacent obstacles 1

Rigging necessary to remove 357 28.6 1 and install the check valves '

Cutting and removal of the old 5086 406.9 1 ,

check valves, and the prep, fit-up, and welding of the new check valves ,

Health Physics coverage and 288- 23.0 3-

. other supervision Sub-Total 6055 484.4 Coneingency 2883 230.6 2 Total 8938 715.0 Note 1 - The man-hour predictions are based cut actual work performed on the outboard feedwater check valves multiplied by 0.080 R/hr to get the man-rem predictions.

Note 2 - We feel the exposure analysis is low since it is based on actual work performed outside of the primary containment. Our experience has-shown that to perform a similar task'inside the containment takes considerably more man-hours. A contingency of 50% of the total man-hours from Note 1  ;

i tasks is utilized for this case.

Note This item is an estimate because it was not part of the scope of f the outboard check valve replacement. l The installation of shielding could reduce the dose rate in the general ,

I area of the inboard feedwater check valves from 80 millirem per hour to 40 millirem per hour. This would result in a savings of 230 millirens from .

Note 1 tasks. But, due to the high dose rate in the immediate area where shielding would be installed, the amount of_ man-rems. consumed would be 294.  !

Therefore, the data.for shielding was not included in the analysis.

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U. S. Nuclear Regulatory Commission VERMONT YANKEE NUCLEAR POWER CORPORATION March 26, 1982 Page 3 CONCLUSIONS It is Vermont Yankee's judgement that because of the major improve-ments already gained in the leakage integrity of the feedwater lines, the potential consequences to the health and safety of the public are suf-ficiently reduced such that replacement of t' e inboard check valves is not warranted. The ALARA analysis reveals the posure range to be between 484 and 715 man-rems. The total man-rem exposue: for the fourth quarter of 1981, which encompasses the refueling outage, was 541 man-rems. Therefore, the primary containment portion of the feedwater check valves replacement represents from 89% to well over 100% of the radiation exposure absorbed by workers during an outage of average duration and work load such as the 1981 refueling oitage. We feel the benefits of replacing the existing inboard feedwater check valves do not outweigh the risks associated with the high radiation exposure.

It is also, therefore, oir intention to retain the present exemption to the Type C Leak Rate Test Program for the inboard check valves (Reference (b)), and place the new outboard check valves on the schedule for Leak Testing per Appendix J. The Technical Specifications will be revised as necessary pending your formal review of our Reference (b) including the subsequent revisions.

We trust this information la satisfactory; however, should you have any questions do not hesitate to call.

Very truly yours, VERMONT YANKEE NUCLEAR POWER CORPORATION

{ A E.W ackson Man ger of Operations i

EWJ/dm cc: USNRC, Washington Attn: Mr. D. Collins Radiological Assessment Branch

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