ML20151A556

Safety Evaluation Supporting Amend 19 to License DPR-3

ML20151A556
Person / Time
Site:	Yankee Rowe
Issue date:	11/12/1975
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20151A549	List: ML20151A546 ML20151A552 ML20151A556 ML20151A560
References
NUDOCS 8011030791
Download: ML20151A556 (3)

Text

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- f UNITED STA]LS. (

c"'. NUCLEAR REGULATORY COMMISSION

-) W ASHINGToN, D. C. 20555 4" :

SAFETY EVhLUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION ._

E SUPPORTING AMENDMENT NO.19 TO FACILITY LICENSE NO. DPR-3 CHANGE NO.124TO THE TECHNICAL SPECIFICATIONS _

YANKEE ATOMIC ELECTRIC COMPANY 9 1

YANKEE NUCLEAR PONER STATION (YANKEE-RONE) f DOCKET NO. 50-29 M

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d Introduction q.

By application dated August 19, 1975 and supplement dated November 3, 1975, .d Yankee Atomic Electric Company (the licensee) proposed to replace the WQ.j existing primary vent stack monitoring system with an improved airborne .

radioactivity sampling and monitoring system. This proposal involves the replacement of descriptive pages in Section 215 " Radiation ]l Monitoring System" of the Facility Hazards Summary Report which is q incorporated in.the Technical Specifications appended to License No. ,

DPR-3 for the Yankee-Rowe reactor. E Discussion {

The existing provisions for monitoring radioactivity in airborne l effluents discharged from the primary vent stack at Yankee-Rowe consist of four thin walled Geiger-Muller tubes, operated in parallel through an impedance matching circuit located near the detector. The primary vent stack discharge detector is mounted on a framework in the stack.

The signal output from the detector is indicated on the radiation monitoring equipment panel in the control room. The indicators include a back ground flasher, an alarm lamp and an indicating meter. The alarm circuit in this monitoring system provides visible and audible indications in the event of abnormal system operating conditions. Provisions for recording the detector signal output are also included. The capability of f..is system is limited to monitoring radioactive gases and it cannot i be readily calibrated.

The licensee proposes to remove the existing primary vent stack discharge detector system and to replace it with a complete state-of-the-art air-borne radioactivity nonitoring system using isokinetic sample probes which .

are installed in the main plant vent stack. The new main plant stack 4

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monitoring sys'em t provides for continuous off-line monitoring of radio- ( gf activity in stack effluents, including gaseous activity, particulates and riess!

iodines.' This system also includes features forLeonvenient calibration. gg.

A' single equipment console in the main control room will house the. noble s.!

gas, the particulate and the radiciodine monitors for the plant vent ~1 7.9 stack, including chart recording and alarms. The installation of the new 55%;;;;

main plant stack monitoring system involves the following modifications: ,{f f P

1. Removal of the existing stack monitoring equipment and sealing of gg.{:M all plant stack penetrations resulting from the equipment removal, t .,me -

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2. Installation of the isokinetic sampling probes through four pene- 25 71 trations-in the plant vent stack, ==:

3. Installation of the enclosure, that houses the particulate, gas, and ,

the iodine de'tectors and' associated electronics, on top of the g~]_.

Primary Auxiliary Building roof, and p ==~

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4. Mounting of the remote chart recorders and alarm modules on the  ;

equipment console in the main control room. g

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c Evaluation .

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Based on our review of'the description and the P 4 ID's provided by the U .

licensee, we find that the proposed isokinetic sampling and monitoring arrangement will assure representative sampling of airborne effluents E.

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from the vent stack during normal and anticipated operational occurrences. .T The vent stack monitoring system is not provided for monitoring or controlling releases of radioactivity that might result from accidents.  :

The radiological consequences and'aonitoring of such accidents have

, previously been evaluated by us independent of the stack monitoring capability and found to be acceptabic. The type of analyses (gaseous, particulate and radiciodine) and the instrument sensitivities provided ..

by the modified vent stack effluent monitoring system are in accordance with the guidelines of Regulatory Guide 1.21. We find that the licensee's design is consistent with current industry practices and state-of-the-art technology. Provisions are included for readout and alarm on each type of. analyses to assure that the operator will be advised of system performance and effluent releases below specified release limits. Sample stations ._

will be included to permit calibration or grab sampling. and analyses if .fi the main plant stack radiation monitoring system is inoperable. The proposed modifications do not involve an unreviewed safety question.

Based on our review of the information submitted by the licensee, we find that the proposed modificatione will provide an upgraded capability for

- monitoring radioactivity (gaseous, particulate and radioiodine) in air-borne effluents from the vent' stack. If the modifications are not made, 4

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ei only gaseous activity in the stack effluents'will be monitored with the

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existing primary vent stack discharge detector. The modifications, then,

.d will provide the necessary means for improved control of routine releases from the Yankce-Rowe plant to the environs and will enhance the safety of plant operations. Therefore, we conclude that replacement of '

the existing plant stack radiation monitoring system is acceptable as s proposed. The modifications will be completed during the present outage f for refueling Yankec-Rowe with Core XII. The modified plant stack radia- ~

tion motoring system will be placed into service upon resumption of operation with Core XII.

Conclusion ll; h'c have concluded based on the considerations discussed above, that:

(1) bec'ause the change does not involve a significant increase in the 5l a

probability or consequences of accidents previously considered and does not involve a significant decrease in a safety margin, the change does not involve a significant hazards consideration, (2) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, and (3) such ac+.ivitics will be conducted in compliance with the Commission's regulations and the issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the publ.ic.

.Date: NOV 121975

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