ML20214N528

Forwards Interim Operation Plan for Control Room Ventilation Sys at Facility,For Use During Startup.Plan Will Allow Startup Activities to Proceed as Scheduled

ML20214N528
Person / Time
Site:	Braidwood
Issue date:	09/09/1986
From:	Miosi A COMMONWEALTH EDISON CO.
To:	Harold Denton Office of Nuclear Reactor Regulation
References
NUDOCS 8609160335
Download: ML20214N528 (5)

Text

_ _____

~

i -) WW M e

- One First Nabonal Plaza Checa00, Illinois b

V

. Address Reply to: Poet Omco Box 767

. Chcago, IEnois 60000 - 0767 September 9, 1986 Mr. Harold R. Denton U.S. Nuclear Regulatory Commission Office of. Nuclear Reactor Regulatory Washington, DC. 20555

Subject:

Braidwood Station Unit 1 Control Room Ventilation System Interim Operation Plan

Reference:

August 18, 1986 P. Thornton letter to H. Grossman Motion for Authorization of Fuel Loading and Precritical Testing

Dear Mr. Denton:

Attached is the interim operation plan for the Control Room Ventilation (VC) System at Braidwood. This plan is intended to be used during the startup of Braidwood Unit 1.

Current preoperational testing commitments (Final Safety Analysis Report, Table 14.2-36) require that_VC System' testing be completed prior to Unit 1 fuel load. However, there is no technical basis for test completion and full system operability at that time.

~

Control room air filtration and positive room pressures are not needed until fission products are generated. Only airflow is required for cooling purposes during the precritical testing phase.

The VC System interim operation plan requires that both equipment trains of the system be preoperationally tested prior to Braidwood Unit 1 initial criticality. The tests include demonstrating that each train can maintain design positive pressures in all areas of the control room boundary with the boundary temporarily sealed. However, during plan operation.up to 5% reactor power, a slight positive pressure will be maintained in the boundary to allow Unit 2 cable pulling activities to proceed. Plant safety will not be compromised since the control room boundary may be sealed to maintain design room pressures in the unlikely event of a high radiation condition.

8609160335 860909 PDR A ADOCK 05000456 PDR dh

This plan will allow Unit 1 startup activities to safely proceed as scheduled. It will also allow Unit 2 construction to continue on a timely basis during the startup of Unit 1.

NRC concurrence of this plan is requested. Please direct any questions you may have to this office.

One signed original and fifteen copies of this letter and enclosure are provided for your review.

Very truly yours,

^

Lapu A. D. Miosi Nuclear Licensing Administrator

/klj cc: J. Stevens 2081K

Braidwood Control Roon Ventilation Systen

, Interim Operation Plan

Reference:

Letter from Peter Thorton to Herbert Grossman dated August 18, 1986 - Motion-for Authorization of Fuel Loading and Precritical Testing The Control Room Ventilation (VC) System at Braidwood is common to Unit 1 and Unit 2. It serves the control room, auxiliary electric rooms, upper cable spreading room, heating, ventilating and air conditioning equipment rooms and various other areas of the plant. The system is designed to provide uncontaminated supply air to areas served by it for cooling purposes and to maintain these areas at positive pressures with-respect to surrounding areas of the Auxiliary and Turbine Buildings. Two identical trains of equipment are provided for redundancy. A complete description of the system is provided in Section 9.4.1 of the Byron /Braidwood Final Safety Analysis Report (FSAR).

Preoperational testing commitments for the VC system can be found in FSAR Table 14.2-36. These commitments require that both system trains be fully tested prior to Unit 1 fuel load. However, there is no technical basis for this deadline. The completion of system testing is not required until fission products are generated. As a result, the following interim operation plan will be utilized for the VC system at Braidwood.

I. Precritical Testing Phase During Unit 1 fuel loading and reactor system testing prior to initial reactor criticality, fuel will not be irradiated and fission products will not be generated. To preclude accidental reactor criticality during this period, Commmonwealth Edison will implement special measures which include maintaining the boron concentration in the reactor coolant system and makeup water system at or above 2000 parts per million. Details of these measures are provided in the referenced letter. As a result, radiological source terms will not exist prior to the planned initial criticality. Therefore, high efficiency particulate adsorber (HEPA) and charcoal filtration, positive room pressure, equipment redundancy and other safety features of the VC system are unnecessary. Only airflow must be provided to properly cool areas within the control room boundary.

To meet the cooling requirements for areas served by the VC system during the precritical testing phase, the following will be completed prior to Unit 1 fuel load:

Ductwork of one train of the VC system will be installed and the fans of one train will be available to run.

. I I .* Power Operation Beyond initial criticality, fission products are generated at rates directly proportional to the reactor's thermal power level. As reactor power increases, more radiological source. terms exist.

1 During' power operation, the VC system must function as designed to protect plant operators from increasing source terms. At Braidwood, j

the VC system is expected to be essentially functional prior to Unit l initial criticality except for the capability to maintain positive room pressures. Positive room pressures must be maintained inside the control room boundary to prevent unfiltered inleakage from other i plant areas. The VC system is designed to maintain the upper cable spreading room at a positive pressure of 0.02 inches water gauge and

! all other control room areas at positive 0.125 inches water gauge with respect to areas outside the control room boundary. However, maintaining these p'ositive pressures requires proper sealing of the i

control room boundary. . Adequate boundary sealing cannot be achieved during the construction of Unit 2. Design room pressures c'annot be I

maintained until Unit 2 cable pulling activities are essentially complete.

To provide an adequate margin of plant safety during power

+

operation, the following~will be completed prior to initial reactor criticality:

Both trains of.the VC system will be air balanced and i preoperationally tested. Also, HEPA and charcoal filters will be in-place tested. The preoperational tests will demonstrate that, f with the control room boundary temporarily sealed, each system train.

is capable of maintaining the upper cable spreading room at a positive pressure of 0.02 inches water gauge and all other control a room areas at positive 0.125 inches water gauge with respect to surrounding areas.

To prevent unfiltered inleakage into the control room boundary and to allow Unit 2 cable pulling to be completed without delay, the '

control room boundary will be maintained at a slightly positive pressu're at initial criticality and durina Unit 1 operation up to 5%

reactor power.

! Prior to Unit 1 operation above 5% reactor power level, the control room boundary will be adequately sealed to maintain the upper cable spreading room at a positive pressure of 0.02 inches and all other I

control room areas at positive 0.125 inches water gauge with respect to surrounding areas.

In summary, this interim operation plan for the VC system-will j allow Braidwood Unit 1 startup activities to proceed without compromising plant safety. VC System air-balancing, filter-testing and preoperational

]

testing will be complete prior to the generation of-fission products.

1 I

i i

-- .- . - - - .- m. _ _ _ _ _ _ . . - _ . - - - _ _ _ _ _ _ . - - _ - _ _ _ _ _ ___ __ _ _ _ _ _ . - _ _ _ - _ _ - -

,. ~

, . Also, this plan will avoid the delay of Unit 2 construction activities during Unit 1 startup. The pulling of Unit 2 cables will be able to proceed while maintaining positive pressure inside the control room boundary. In the unlikely event that high radiation levels exist in the plant during startup, the control boundary may be sealed to maintain design room pressures.

DPC/bmb/8386b

[

i

. . . . -_ _ _ _ _ . . - . - - - , , , _ , _ . - . , . . _ . -