1CAN088702, Provides Inadequate Core Cooling Monitoring & Display Sys Implementation Ltr Rept,Per 870306 Commitment

Provides Inadequate Core Cooling Monitoring & Display Sys Implementation Ltr Rept,Per 870306 Commitment

ML20237L375
Person / Time
Site:	Arkansas Nuclear
Issue date:	08/14/1987
From:	Enos J ARKANSAS POWER & LIGHT CO.
To:	Dick G NRC
Shared Package
ML19292H670	List: 1CAN088702, Provides Inadequate Core Cooling Monitoring & Display Sys Implementation Ltr Rept,Per 870306 Commitment
References
RTR-NUREG-0737, RTR-NUREG-737, TASK-2.F.2, TASK-TM 1CAN088702, 1CAN88702, NUDOCS 8708200196
Download: ML20237L375 (4)

Text

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ARKANSAS POWER & LIGHT COMPANY POST OFFICE BOX 551 LITTLE ROCK ARKANSAS 72203 (501) 371-4000 August 14, 1987 1CAN088702 U. S. Nuclear Regulatory Commission Washington, D.C. 20555 ATTN: Mr. George Dick

SUBJECT:

Arkansas Nuclear One - Unit 1 Docket No. 50-313 License No. DPR-51 ANO-1 Inadequate Core Cooling Monitoring and Display System (ICCMDS) Implementation Letter NUREG 0737, Item II.F.2

Dear Mr. Dick:

Our March 6,1987 letter (1CAN038701) committed to providing you the implementation letter report for the ICC instrumentation installed per NUREG-0737, Item II.F.2. The purpose of this letter is to fulfill that commitment.

This implementation letter report is formatted in accordance with Enclosure 3 of your January 14, 1987 letter (1CNA018707).

(1) Notification that the system installation, functional testing and calibration are complete and test results are available for inspection.

Installation of the Reactor Vessel Level Monitoring System (RVLMS), the Hot-Leg Level Monitoring System (HLMS),16 Core Exit Thermocouple

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(CETs), the Mimic Display Panel, Fluorescent Display Units (FDUs) and ,

signal processing software was completed during the ANO-1 seventh refueling outage (1R7).

The functional testing and calibration for the ICCMDS were completed, and these test results are available for your inspection. However, some software revisions are being incorporated in response to requests

! made by the operations staff during functional testing. Additional l testing will be performed after these revisions are made in order to )

ensure that the system performance meets the requirements of l NUREG-0737, Item II.F.2 and the expectations of the operations staff.

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August 14, 1987 (2) Summary of licensee conclusions based on test results, e.g. :

(a) the system performs in accordance with design expectations and within design error tolerances; or (b) description of deviations from design performance specifications and basis for concluding that the deviations are acceptable.

The original RVLMS error table (Table 4 in the Final Design Description (FDD)) was based on preliminary calculations using theoretical data from Technology for Energy Corporation (TEC) reports and algorithms which had not been finalized. Additional calibration error data have been obtained and the RVLMS algorithm methodology has been finalized since submittal of the FDD. Consequently, Table 4 of the FDD has been revised.

Although the RVLMS worst case error has increased over that given in the FDD, the ICCMDS meets the requirements of NUREG-0737, Item II.F.2.

The RVLMS will provide the required reactor water level indication and the advanced warning of the liquid level drop to the top of the core during the blowdown phase of a SBLOCA. As illustrated in Table 4, the RVLMS also provides liquid level trending indication during the refill phase of a SBLOCA.

The HLMS error table (Table 5 in the FDD) has been revised to reflect installed tap elevations, indicated ranges and maximum expected loop errors. Minor tap elevation changes (greatest change is 15 inches) resulted from the inaccessibility of the previously planned locations given in the FDD. The changes in indicated ranges for the hot-leg level instruments were a result of the tap elevation changes.

Additional HLMS error calculations have been performed since submittal of the FDD. Additional error sources, such as insulation resistance degradation for cables, splices and connectors exposed to the harsh environmental conditions following an accident, have been identified and incorporated into the overall error in indicated hot-leg levels.

Although the indicated worst case hot-leg level erroas have increased over those reported in the FDD, the hot-leg level trending capability is maintained with the new error values. Additionally, the HLMS design redundancy (1 wide range instrument and 4 narrow range instruments per hot-leg) allows for adequate measurement of absolute level over the 49 feet of instrumented height.

The CET error table (Table 6 of the FDD) has been revised based on calculations which account for the worst case errors associated with the installed signal processing hardware errors. The table has also been re-formatted to show the worst case full-scale error only.

(3) Description of any deviations of the as-built system from previous design descriptions with any appropriate explanation.

August 14, 1987 The following are deviations in the as-built ICCMDS from the FDD.

These changes have been incorporated into the revised FDD which is attached to this letter. Revisions are denoted by vertical lines in the right margin.

(a) The table of contents has been revised to reflect the change described in (1) below.

l (b) As described in response to (2) above, Tables 4, 5 and 6 of the FDD have been revised.

(c) Descriptions of the operating voltages for the microprocessor RCS pressure and temperature input provided in Table 2 of the FDD have been revised.

(d) A typographical error exists in the first bullet of Table 1 of the FDD. "Intell" should be " Intel".

(e) The last sentence of the fourth paragraph of Section 4.3.2 on,page 18 is modified to read " Input data is also validated by simple range checks for absolute value". Range checks for rate of change are not used to validate input signals.

(f) The last sentence of page 18 is changed to read "...with addressable ranges of 300 to 9600 baud to the SPDS." The range j originally given in the FDD (300-19,800 baud) was a mistake carried over from a TEC report which was used in specifying the ANO-2 Data Acquisition System (DAS). The revised addressable range applied to the ANO-1 DAS was provided by Exoser,scrs.

(g) The first sentence of the second bullet on page 19 is changed to read " Presenting a list of temperatures from the core exit." This is a clarification of the original statement made in the FDD. ,

i (h) The final bullet under Section 4.4.2.1 on page 23 is deleted. {

Directions for manual start-up and initialization are provided in i the system operating instructions. Due to the simplicity of +he start-up and initialization actions, a detailed procedure is tet necessary.

(i) The electrical power requirement for the ICCMDS, given in Section 5.2.2 on page 29 is changed from 425 Watts to 1000 Watts. The electrical power requirement given in the FDD did not include the power to the Radcal Level Instrument (RLI) heaters.

(j) The last sentence of the first paragraph in Section 5.2.6 on page l 30 is changed to read "Each connector is seismically supported by I mounting brackets attached to the top of the service structure." l This is a clarification of the seismic support for the cable connectors.

(k) The word " cold-worked" is removed from the first and last sentences of the first paragraph of Section 5.3.2 on page 31.

This change accurately reflects the installed tap sleeve material.

l August 14, 1987 l

(1) Section 6.2.2.3 on page 36 is deleted. This section described in-core recalibration for power monitoring purposes. Power monitoring is not a required function of the ICCMDS.

1 (m) The second sentence of Section 10.1.12 on page 44 is modified to read " Timed passwords are provided to enable maintenance personnel ,

access to the system." The third sentence is deleted. The l password serves to prevent inadvertent modification to ICCMDS j setpoints. Although the password is controlled within AP&L, there 4 are no present plans to periodically change it.

1 (n) Section 10.1.14 on page 44 is revised to read "During operation, the data acquisition system removes failed sensors from ,

calculations and clearly flags these sensors. The operator can ']

remove from service any failed sensors." The purpose of this change is to clarify the method by which the DAS and the operator may treat invalid indications.

(o) Figure.2 has been corrected to show accurate CET locations.

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4. Request for modification of Technical Specifications to include all ICC instrumentation for accident monitoring.

Technical Specifications covering the Limiting Conditions for Operation and the Surveillance Requirements for the ICCMDS are being prepared.

The expected date for submittal of the Technical Specifications is September 30, 1987.

5. Request for NRC approval of the plant-specific installation.

The ANO-1 ICCMDS is installed and operational. Although minor software modifications are being made (see response to (1) above), AP&L requests NRC approval of the plant specific installation.

6. Confirm that the E0Ps used for operat-or training will conform to the technical content of.NRC approved E0P guidelines (generic or plant specific).

As we have not yet received NRC approval of our E0P technical guidelines, we cannot confirm that the E0P conforms to the technical content of NRC approved E0P guidelines. However, in updating the E0P we followed the E0P technical guidelines which were submitted to you in our July 3, 1986 letter (ICAN078607).

Very truly you ,

J. Ted F s, Manager Nuclear ngineering and Licensing JTE/MJS/sd l

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