ML20246J313

Safety Evaluation Concluding That Operators Role in Mitigating High Energy Line Break at Facility Acceptable

ML20246J313
Person / Time
Site:	Fort Saint Vrain
Issue date:	07/07/1989
From:	West G Office of Nuclear Reactor Regulation
To:
Shared Package
ML20246J287	List: ML20246J279 ML20246J313 ML20246J319
References
NUDOCS 8907170333
Download: ML20246J313 (3)

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NUCLEAR REGULATORY COMMISSION i

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EPCLOSURE 1 1

SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATING TO OPERATOR'S ROLE IN MITIGATING A HIGH ENERGY LINE BREAK PUBLIC SERVICE COMPANY OF COLORADO FORT ST. VRAIN NUCLEAR GENERATING _ STATION )

DOCKET NO. 50-267 3.0 INTRODU,CTION AND BACKGROUND On February 22, 1986, the staff met with the licensee to discuss the qualification of equipment at Fort St. Vrain under the provisions of 10 CFR 50.49, the equipment qualification rule. One subject discussed at this meeting was the potential role of the operators following a high energy line break (HELB). The staff was concerned about the ability of the operators to carry out their role, given the potentially harsh conditions that could exist in the plant following the HELB.

By letter dated April 6,1986, the staff formally requested certain information concerning technical aspects of this problem. The licensee responded in letters dated June 26, 1986, and January 15 and March 31, 1987. Further review of the licensee's responses caused the staff to ask additional geestions en June 24, 1988, concerning human factors aspects of the operator's role. The licensee responded to these questions by letter dated December 9, 1988.

The staff requested review of the licensee's first set of responses by its contractor, Idaho National Engineering Laboratory (INEL). INEL's review is found in the technical evaluation report (TER) provided as Enclosure 2 to cur letter.

2.0 EVALUATION ]

2.1 Technical Response l The licensee was initially asked to describe the response of the operators to the HELS and to provide an evaluation of the operator's ability to make that response. The licensee noted that under normal circumstances environmentally qualified remote equipment (valves) or valves with remote hand wheels would be used as part of the shutdown process. Only if there was a single failure of the qualified valves would the operator potentially have to enter a harsh environment.

The initial conclusion of the staff was that this could be accomplished in the environment following the HELB, where the temperatures were expected to be less than 140 degrees F about 30 minutes after the HELB is isolated.

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e This is' described in detail in the INEL TER. However, before concluding the situation was acceptable, the staff requested more information frcm the licensee on the human factors aspects of this g problem.  ;

2.2 Human Factors Respcnse The staff's human factors concerns covered four majcr areas. These are: i

- Ability to identify and manipulate manual valves.

- Ability to correctly read instrumentation.

Ability to protect the operators and operator communication.

Post-HELB temperature, humidity, noise, and lighting conditions.

These are discussd in the following sections.

The licensee has provided a listing of the valves that would have to be manipulated. The licensee has stated that the valves are identified with tags and the operators are familiar with their location from procedures, training, and plant walkdowns. The licensee has reviewed the ability of the operators to manipulate the valves and concluded that this can be accomplished. The staff has also performed a partial walkdown of the system and noted that the valves are easily identified. Therefore, the staff concludes that the operators will be able to identify and correctly manipulate the valves for plant shutdown following an HELB.

The instruments that have to be read during the shutdrwn sequence are located either in the plant er in the control room for quick installation when they are needed. The licenser has provided information on the instruments that indicates they have sufficient accur0cy to enable the cperators te monitor the plant cooldown process. The staff has seen the installation of this equipment during a plant walkdcwn and verified its accessibility and availability for use. Therefnre, the staff concludes the instrumentation is adequate for the intended purpose.

The licensee has reviewed the ambient conditions under which the operatcrs would have to perform the required tasks. The licensee has found that the temperature, humidity, and lighting ccnditions are adequate for the operators to perform their tasks. Specifically, the temperatures in the plant would be less than 145 degrees F within 45 minutes following the isolation of the HELB. In addition, air packs and flashlights are available for the operators to use. Given these conditions, the use of protective clothing does not appear to be necessary. The operators will be able to communicate with radios, or use the plant Gaitronics system as a backup.

Therefore, the staff concludes ambient conditions for performing the opera-tors tasks are acceptable.

3.0 C0hCLUSIONS In view of the above, the staff concludes that its concerns about the ability of the operators to respond to an HELB have been adequately

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^ addressed by the licensee. Since the operators in most cases.will not have to' enter a harsh. environment, the measures proposed by.the licensee are adequate.' The' staff also concludes that the technical and human factors aspects of how.the operators will respond.to an HELB are acceptable.

-Date: ' July 7,1989 Principal Contributors: Garmon. West,- Jr. , LHFB Kenneth L. Heitner, PD-IV o:

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