ML20044A969

Safety Evaluation Supporting Amend 127 to License DPR-61

ML20044A969
Person / Time
Site:	Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png
Issue date:	07/09/1990
From:	Office of Nuclear Reactor Regulation
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ML20044A967	List: ML20044A968 ML20044A969
References
NUDOCS 9007170103
Download: ML20044A969 (3)

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SAFETY EVALUATION BY THE OFFICF 0F NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 127 TO FACILITY OPERATING LICENSE NO. DPR.61 CONNECTICOT YANKEE ATOMIC POWER COMPANY HADDAM NECK PLANT DOCKEY NO. 50 213 INTRODUCTION Pursuantto10CFR50.90,ConnecticutYankeeAtomicPowerCompany(CYAPCO)has proposed to amend Operating License No. OPR-61 for Haddam Neck Plant. By Established|letter dated March 14, 1990]] CYAPCO proposed to emend the Technical Specifications (TS) by adding a Specia1 Test Exception 3.10.4, Position Indication System-Operating.

This will allow testing of the individual rod position indication (IRPI) system during power operation of the Haddam Neck Plant. The proposed Technical Specification (TS) will allo. suspension of the following limiting conditions for operation (LCOs) for a maximum of 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> for each cycle during the performance of the test:

Movable Control Assemblies 3.1.3.1 Position Indicating Systems-Operating 3.1.3.2 Shutdown Rod Insertion Limit 3.1.3.5 ControlGroupInsertionLimits(4 Loops) 3.1.3.6.1 Control Group Insertion Limits (3 Loops) 3.1.3.6.2 DISCUSSION Individual rod position is obtained by a linear variable differential transformer (LVDT) on each of the 45 control rod housings. The rod drive shaft acts as a permeable core for the transformer. Thus, as the rod position changes, the magnetic coupling between the primary and secondary windings will also change.

As the shaft moves higher within the housing, the magnetic coupling increases causing an increase in the transformer secondary voltage. The secondary voltage is fed to an AC to DC converter which provides a DC signal proportional to rod position. A digital voltmeter is calibrated to read out individual indication of rod position in steps. The individual control rod position indication system is affected by temperature. The purpose of the test is to calibrate the IRP!

system to compensate for the temperature effects.

The IRPI system drif t due to temperature has been an observed phenomena since early operation of the plant. The IRPI system must be recalibrated during operation and various tests to adjust for temperature fluctuations. The recalibration is necessary to assure the plant is in compliance with various TS requirements. The proposed test would allow the IRPI to fluctuate with temperature and not require the IRPI to be recalibrated to show compliance with the TS during the test. The control rod position indications will be recorded hi h Ndygg a coneladon bebeen temperah ad coM M

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EVALUATION The IRPI system consists of 45 control rods in four banks (A.B.C and D). Banks C and D are the shutdown banks and contain 8 and 12 rods respectively.

Banks A and B are the control banks and contain 17 and 8 rods respectively. To perform the test three conditions must be met: 1) Each control rod in Banks A. C and D will be verified to be withdrawn to at least 317 steps (full out-of-core position)within24hourspriortothestartofthetest.2)BanksA,Cand D will not be moved during the test, and 3) The Group Position Indication (GPI) system is operable during the performance of the test. In addition, with any movement of rods in Banks A, C or D the Action Statement will require that the test be terminated and that the IRPI be restored to operable status within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> or be in at least hot standby within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />. The test will basically be to vary the reactor coolant temperature in MODES 1 or 2 using control Bank B and boron concentration and observe and record the IRPI fluctuation.

Control Bank B and boron concentration are the usual means for controlling the reactor power during operation. With. control Bank B and boron concentration the plant will be able to fluctuate temperature from 545'F to 585'F. The power range For temperature is between 535'F and 585'F.

Based on these observations a correlation between temperature and rod position indication c'ould be developed essentially over the whole range power operation.

The IRPI system does not provide any input to any automatic safety or control system function at the plant.

The IRPI system is important to safety because it is used to assure that all rods are withdrawn equal to or greater than the required rod insertion limits. The rod insertion limits are maintained by the TS and assure that the minimum shutdown margin is maintained. The rod bottom bistables, which are part of the IRPI, are unaffected by the test and will continue to provide input to the turbine runback feature during the test.

The automatic turbine runback feature is strictly for plant control and has no safety function.

Banks A, C and D will be fully withdrawn and verified to be within their respective rod insertion limits prior to the test. As noted above the TS will not allow any motion of Banks A C, or D during the test.

The test exception is needed because TS Sections 3.1.3.1, 3.1.3.2, 3.1.3.5, 3.1.3.6.1 and 3.1.3.6.2 could be violated as the indicated position may change during the test and exceed TS limits even though the actual position has not.

During the test, rod position will continue to be monitored by the Group Position Indication (GPI) system. Control Bank B must also remain within its rod insertion limits as required by TS Sections 3.1.3.6.1 and 3.1.3.6.2.

In addition, the TS will limit the use of the test exception to 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> each cvele. The correlation will not be used until the plant can verify the Fesults.

In the interim the plant would have both indications available and use the existing rod position indication algorithm.

Based on the above the staff has determined that the proposed TS changes will have no adverse impact on plant safety and will maintain the intent of the current TS. Therefore, the staff concludes that the proposed TS changes are acceptable.

i ENVIRONMENTAL CONSIDERATION This amendment changes a requirement with respect to the installation or use of a facility component located within the restricted area as defined in 10 CFR i

Part 20. We have determined that the amendment involves no significant

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increase in the amounts, and no significant change in the types, of any efflu-ents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure. The staff has pre-viously published a proposed finding that the amendment involves no significant 3

hazards consideration and there has been no public coment on such finding.

Accordingly, the amendment neets the eligibility criteria for categorical exclu-sion set forth in 10 CFR 51.22(c)(9). Pursuant to 10 CFR 51.22(b), no envi-i renmer.tal impact statement or environmental assessment need be prepared in l

connection with the issuance of the amendment.

5.0 CONCLUSION

We have concluded, based on the considerations discussed above, that (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, and (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendment will not be inimical to the comon defense and security or to the health and safety of the public.

Dated:

July 9, 1990 Principal Contributor: A. Wang i

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