ML19211A097
| ML19211A097 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 10/29/1979 |
| From: | Schwencer A Office of Nuclear Reactor Regulation |
| To: | Proffitt W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| Shared Package | |
| ML19211A098 | List: |
| References | |
| NUDOCS 7912170029 | |
| Download: ML19211A097 (3) | |
Text
{{#Wiki_filter:pv' t PDrL wm [ [0, UNITED STATES y e( i NUCLEAR REGULATORY COMMISSION ';W; * * ) ,E WASHINGTON, D. C. 20555 i OCTOBER 2 g g/g .m. Docket Nos. 50-280 and 50-281 Mr. W. L. Proffitt Senior Vice President - Power Virginia Electric and Power Company Post Office Box 26666 Richmond, Virginia 23261
Dear Mr. Proffitt:
The staff has recently completed a review of the LER.'s and Technical Specification requirements related to the Control Rod Position Indication Systems (RPI) at Westinghouse PWRs. We have determined that a wide varia-tion exists in the number of LERS received and the technical specification requirements and have, therefore, decided to clarify our requirements. At the time of development of the Standard Tec1nical Specifications, a systematic attempt was made to clarify potentially ambiguous specifications. One such specification was the control rod misaligment specification for Westingnouse-designed reactors. Westinghouse has perfomed safety analyses for control rod misaligment up to 15 inches or 24 steps (one step equals 5/8 inen). Since analysis of misaligments in excess of this amount have not oeen suomitted, we nave imposed an LCO restricting continued operation with a misalignment in excess of 15 inches. Because the analog control rod position indication system has an uncertainty of 7.5 inches (12 steps), when an indicated deviation of 12 steps exists, the' actual misalignment may be 15 inches. This is because one of the coils, spaced at 3.75 inches, may be failed without the operator knowing about it. The Standard Technical Specifications were written to eliniinate any confusion about this, and allow a ceviation of up to 12 indicated steps. Surveillance requirements, on the incication accuracy of 12 steps were also prepared to ensure that the 15 inch LCO is met. There is no difference intended in requirements issued for any Westinghouse reactor. Westinghouse has informed the NRC that all of their custaaers have been infomed of this and that all the ifcensees should be folicwing the same procecures regardless of the language of their Technical Specification. That is, plants with Tecnnical Specifications written in tems of 15 inch misalign-ment should be consicering the 12 step instrument inaccuracy when monitoring roc position. A related preolem is that the installed analog controi rod position indicating system equipment may not, in scme areas, ce adequate to maintain the control rod misaligment speification recuirement because cf drift preolems in the caliaration curves. This is evidenced oy numerous LER!s concerning red position incication accuracy. In these cases, tne uncer ainty may be more than 12 steps. 1595 246 mzoo
Mr. W. L. Proffitt CCTCBER 11 59 Virginia Electric and Power Company The present Westinghouse Standard Technical Specifications (Tindicated positio W-STS) require all full length control rods to be positioned within + 12 steps of their group step counter demand position. Since numerous problems have developed in signal conditioning circuits for displaj indication.of control rod position, the staff has detemined that the " indicated position" requirement may be fulfilled by voltage measurements obtained from the position indication mechanism (and therefore no LER need be sucmitted) provided a sufficient data base has been established to ensure a correlation between voltage and position. A copy of the current, applicable W-STS Specifications (3/4.1.3.1 and 3/4.1.3.2) are attached for your informati'on and consideration. It is requested that you review your present technical specifications to ensure that the control rods are required to be maintained within + 12 steps indicated and that the rod position indication system is verified to Ie accurate to within 12 steps. If your review indicates that this is not the case, you should so inform the Commission within 30 days of your receipt of this letter together with your plans to correct the deficiencies. Any needed correcti-ve actions may take several foms; such as (1) revising your technical specifications to limit control rod misaligreent to no more than + 12 steps indicated position, (2) seeking relief by perfonning analyses justiTyiag (with penalties if needec) greater misalignments, or (3) proposing alternate or supplemental monitoring specifications to demonstrate canpliance with the + 12 step indicated aligment requirement. If you have any questions on this matter, please contact us. Sincerely,
- asenw A. Schwencer, Chief Operating Reactors Branch il Division of Operating Reactors
Enclosure:
W-STS Specm, _ cations 3/4.1.3.1 anc 3/4.1.3.2 1595 247 cc: w/ encl osure See next page
'979 -~~. Mr. W. L. Proffitt OCTOBER a ' Virginia Electric and' Power Company cc: Mr. Micha'el W. Maupin Hunton and Williams Post Office Box 1535 Richmond, Virginia 23213 Swem Library College of William and Mary Williamsburg, Virginia '23185 Donald J. Burke U. S. Nuclear Regulatory Commission Region II Office of Inspection and Enforcement 101 Marietta Street, Suite 3100 Atlanta, Georgia 30303 1 1595 248 ..~f ; . _.i -.r G l G W%W N =.. -}}