ML19309A749

Inadvertently Deleted Page of Cycle VII Startup Test Rept.

ML19309A749
Person / Time
Site:	Vermont Yankee
Issue date:	03/24/1980
From:	VERMONT YANKEE NUCLEAR POWER CORP.
To:
Shared Package
ML19309A746	List: ML19309A745 ML19309A749
References
NUDOCS 8004010243
Download: ML19309A749 (1)

Text

s These checks included various manual and computer checks of the new data constants. A check for consistency of the data was also done by Yankee Atomic Electric Company and found to be satisfactory.

SHUTDOWN MARGIN TESTING:

The shutdown margin test was performed on October 13 1979 The highest worth control rod, 14-23, was fully withdrawn and shutdown margin was demonstrated with rod 18-19 for which a rod worth curve had been calculated.

A shutdown margin of at least 1.128% a66 K/K was demonstrated. The reactor remained suboritical throughout the test. This satisfied the Technical Specification requirement of demonstrating a shutdown margin of at least 0 32%ZiK/K at the beginning of cycle 7. For cycle 7, beginning of cycle is the point of minimum shutdown margin; therefore, margin has been established for the whole cycle.

IN-SEQUENCE CRITICAL:

The sequence used for the in-sequence critical was control rod withdrawal sequence 7-A-1. On October 27, 1979 control rods were withdrawn in sequence until criticality was attained. Criticality was achieved on the seventh rod in group 2 (rod 26-31) at position 8. The moderator temperature was 1100F.

The actual critical rod pattern and the General Electric prediction agree within t1%21 K/K. Figure 2 shows the actual, predicted, and 21% dLK/K critical rod patterns.

ROD SCRAM TESTING:

All centrol rods were scram tested on November 20, 1979 through November 23, 1979 All insertion times were within the limits given in Technical Specifications. The results of the testing is shown in Table I.

Rod coupling verification was also performed over the period of November 20, 1979 through November 23, 1979 and all control rods were found to be coupled.

THERMAL HYDRAULIC LIMITS AND F0WER DISTRIBUTION:

Since startup, peaking factor, critical power ratio, maximum fraction of limiting power density, and maximum average planar linear heat generation rate were all checked daily using the process computer. All checks were satisfactory and within Technical Specification limits.

The results of the Backup Core Limits Evaluation (BUCLE) program were compared to the process computers' calculations for the same conditions. The results were essentially identical and are shown in Table 2. The process computer power distribution was updated by doing a complete set of TIP traces. This updating procedure was performed eleven (11) times during the ascent to power. The results of these updates are shown in Table 3 The LPRM's were calibrated two (2) times in conjunction with the TIP sets. The TIP's and the LPRM's were both functionally tested and found satisfactory.

The process computer power distribution update performed on November 9, 1979 was used as a basis for comparison with an offline calculation performed using the Yankee Atomic Electric Company code, "SIMU LATE" . For the power distribution update of November 9,1979 " SIMULATE" overprediced the peak core average axial power peak by 7.9 percent. In general " SIMULATE" tended to overpredict the lower nodes, while underpredicting the upper noden.

"SIMdLATE" overpredicted the peak radial power by 4 3 percent.

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