ML20127J554

Grants Util 930112 Request for Temporary Waiver of Compliance Re MSL RM Trip Function

ML20127J554
Person / Time
Site:	Millstone
Issue date:	01/15/1993
From:	Calvo J Office of Nuclear Reactor Regulation
To:	Opeka J CONNECTICUT YANKEE ATOMIC POWER CO., NORTHEAST NUCLEAR ENERGY CO.
References
TAC-M85324, NUDOCS 9301250175
Download: ML20127J554 (3)

Text

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'%,,,,,/c hnuary 15, 1993 Docket No. 50-245 Mr. John F. Opeka Executive Vice President. Nuclear Connecticut Yankee Atomic Power Company Northeast Nuclear Energy Company Post Office Box 270 Hartford, Connecticut 06141-0270

SUBJECT:

MILLSTONE NUCLEAR POWER STATION, UNIT 1 - NRR TEMPORARY WAIVER OF COMPLIANCE RELATED TO THE MAIN ETEAM LINE RADIATION MONITOR (TAC NO. M85324)

By letter dated January 12, 1993, Northeast Nuclear Energy Company (NNECO), on behalf of Millstone Nuclear Power Station, Unit 1, requested a Temporary Waiver of Compliance (TWOC) and an exigent amendment to facility Operating License No. DPR-21. The waiver would allow for temporarily bypassing the Main Steam Line Radiation Monitor (MSLRM) trip function (which results in a reactor scram and Group I isolation), for a period not to exceed 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />, in order to allow condensate domineralizers to be returned to service, thereby eliminating the possibility of an inadvertent initiation of the MSLRM trip function.

NNECO's request was also discussed in conference calls between the staff and NNECO on January 13 and 14, 1993. NNECO committed to document the information provided to the staff during the conference calls by January 19, 1993.

On December 29, 1992, while returning a condensate demineralizer to service, a radiation spike occurred resulting in high radiation alarms of the MSLRH and the terbine deck area radiation monitor. The main steam line radiation reading increased from the 350 mR/hr normal background reading to approximately 1300 mR/hr. The MSLRM has a reactor trip setpoint which is designed to initiate at or below the Technical Specification requirement of seven times the normal background reading. To provide margin for instrument uncertainty and the potential for instrument drift, this setpoint is conservatively set at 1700 mR/hr. Upon receipt of an MSLRM trip signal, the reactor scrams and the Group I Isolation valves close.

At this time, NNECO has not determined the cause of the spike. NNEC0 has ruled out the possibility of fuel failure because spike was not received by the off-gas radiation monitor, and the radiation release due to fuel failure would have caused a high radiation level at the off-gas radiation mgitor due to the long half-life of these isotopes. Other isotoses, such as N , that may have caused the spike at the HSLRM, have a very s1 ort half-life and would decay before reaching the off-gas monitor.

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i Mr. John F. Opeka t To prevent the possibility of a spurious radiation spike resulting in reactor i scram and MSIV closure, the requested Technical Specification (15) amendment '

allows NNECO to bypass the MSLRM trip function for up to 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> while i returning condensate domineralizers back to service after ultrasonic resin  ;

cleaning (URC) of the demineralizers. Due to concerns that corrosion products  ;

will collect in the demineralizers, NNECO currently performs URC on two ,

demineralizers per week. While the MSLRM trip function is bypassed, NNECO has  :

committed to compensatory measures. These compensatory actions, which are documented in plant procedures, include having a dedicated operator monitoring the MSLRM and off-gas radiation monitors, and initiating a manual reactor scram, isolating the off-gas discharge valve, and closing the MSIVs in the event that one MSLRM and one off-gas radiation monitor reach their respective high radiation trip setpoints (the trip setpoints do not have to be reached concurrently). The licensee has also committed to remaining at a stable pow'r level during the period of time that these trips are bypassed. These  ;

, compensatory actions provide assurance that the reactor will be scrammed and isolated under conditions when fuel failure is indicated, while minimizing the '

potential for unnecessary isolation and scram during the demineralizer change process.

The staff also notes that the Millstone Unit No. I design basis accident analysis does not take credit for the MSLRM trip function, In the Control Rod Drop Accident (CRDA), the Millstone Unit No. 1 Final Safety Analysis Report assumes all activity from failed fuel rods is immediately transported to the turbine / condenser and is available for leakage from the condenser. The CRDA ,

is only significant at power levels below 20%, therefore, as an extra ,

conservatism. NNECO has committed to performing this condensate demineralizer ,

evolution only at steady state power levels greater than 20%. A CRDA event at greater than 20% power would be of low significance during the time that bypass of the MSLRM trip function is allowed.

NNEC0 has requested the IWOC for the period until the license amendment is approved by the NRC. The Technical Specification change allows the temporary '

bypassing of the MSLRM trip function, for a period no greater than 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />, in order to allow condensate demineralizers to be returned to service. This will allow Millstone Unit No I to continue to safely operate, while minimizing the potential for an inadvertent main steam line isolation valve closure and ,

reactor scram. The NRC staff has concluded, based on our review of your ,

request and the compensatory actions which will be taken during the condensate '

demineralizer change process, that the operation of Millstone Unit 1 in conformance with TS Tables 3.1.1 and 3.2.1, as amended by this request provides an acceptable level of safety and does not present any undue risk to the health and safety of the public. This letter confirms our verbal

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Mr. John F. Opoka authorization of the requested TWOC at 3:20 p.m. on January 14, 1993. This TWOC, with the cited TS requirements, will be in effect until we issue an exigent license amendment or until February 26, 1993, whichever occurs first.

Sincerely.

Original signed by Jose A. Calvo,-Assistant Director for P.egion 1 Reactors Division of Reactor Projects - I/II-Office of Nuclear Reactor Regulation cc: See next page .

Distribution: - ,

Docket file J. Lieberman, OE ,

idC & Local PDRs M. Boyle >

PD 1-4 Plant L. T. Doorflein, RI T. Murley W. Hehl F. Miraglia R. Jones J. Partlow  :

S. Varga J. Calvo J. Stolz '

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• Wanda Jones C. Grimes A. Cubbage

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