ML20209F727
| ML20209F727 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 04/21/1987 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20209F725 | List: |
| References | |
| GL-86-13, TAC-64674, NUDOCS 8704300360 | |
| Download: ML20209F727 (3) | |
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NUCLEAR REGULATORY COMMISSION n
WASHINGTON, D. C. 20555
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO.116 TO DPR-65 NORTHEAST NUCLEAR ENERGY COMPANY, ET AL.
MILLSTONE NUCLEAR POWER STATION, UNIT NO. 2 DOCKET NO. 50-336 INTRODUCTION By application for license amendment dated February 6, 1987, Northeast Nuclear Energy Company, et al. (the licensee), requested changes to the Technical Specifications (TS) for Millstone, Unit 2 as follows:
(1) a new Limiting Condition for Operation (LCO) and a corresponding Surveillance Requirement (SR), TS 3/4.1.7 " Control Rod Drive Mechanisms," has been proposed to assure that control rods cannot be withdrawn prior to establishing conditions consis-tent with the safety analysis, and (2) a change to the LC0 and SR for.the reactor protection system (RPS),, TS 3/4.3.1, would extend operability and sur-veillance requirements, for the Power Level-High trip function, to Mode 3.
DISCUSSION AND EVALUATION On July 23, 1986, the NRC issued Generic Letter (GL) 86-13, " Potential Inconsistency Between Safety Analyses and Technical Specifications." The conclusions of GL 86-13 indicate that the TS may not provide sufficient restrictions to assure that, should a continuous control rod bank withdrawal occur from subcritical conditions, the consequences are within those predicted by the safety analysis.
This conclusion is based upon a comparison of Westinghouse safety analysis and plant TS which show that fewer than a full complement of reactor coolant pumps (RCP's) are permitted to be operating at zero power while the safety analysis assumes that all RCP's are operable.
Under such conditions, the departure from nucleate boiling ratio (DNBR) criteria demonstrated in the safety analysis might not be met in the event of an accident.
The licensee's letter dated November 4, 1986 submitted LER 86-010-00 which reported that the conclusions of GL 86-13 were valid for Millstone Unit 2.
The licensee committed to provide an administrative control for the control element drive mechanisms (CEDM's) to assure that they are de-energized when less than four (all) RCP's are operating; thus, a continuous control bank withdrawal from subcritical conditions would be prevented, The licensee sub-sequently submitted their application, dated February 6, 1987, which provided proposed changes to the TS to assure that the consequences of any continuous control bank withdrawal from subtritical conditions will be less severe than those predicted by the safety analysis.
8704300360 870421 PDR ADOCK 05000336 P
4 The licensee has proposed a new LCO and an associated SR, which reflect a _,
revised evaluation of continuous rod withdrawal from suberitical conditions, to be designated TS 3/4.1.3.7, " Control Rod Drive Mechanisms." The proposed LCO would require the control rod drive mechanisms (CRDMs) to be de-energized in reactor operating Modes 3, 4, 5 and 6 (hot standby and all shutdown modes) unless the reactor coolant system soluble boron concentration exceeds 1720
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t ppm. A boron concentration of 1720 ppm provides sufficient shutdown margin to prevent criticality in the event of a continuous rod withdrawal.
In Mode 3 (hot standby) the CRDM's may be reenergized if ".. 4 reactor coolant pumps are OPERATING, the reactor coolant system temperature is greater than 500 F, the pressurizer pressure is greater than 2000 psia and the hich power trip is operable." The preceding conditions are necessary in order to prevent the DNBR from being less than 1.30 in accordance with the licensee's revised evaluation of continuous rod withdrawal from subcritical conditions.
In the event that LCO 3.1.3.7 is not satisfied, the associated Action Statement requires that the reactor trip breakers be opened within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />; this action would also prevent rod withdrawal. The proposed SR requires that the CRDM's be verified to be de-energized at least once per 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
The proposed changes to the LC0 and SR for the RPS,'TS 3/4.3.1 are consistent with the revised evaluation of continuous rod withdrawal from subcritical conditions. The Power Level-High trip function, which is the subject' of the proposed change, is relied upon to terminate the transient by tripping the reactor. The Power Level-High function would now be reoutred to be operable, and undergo surveillance, in Modes 1,2 and 3; previously these requirements i
only applied to Modes 1 and 2.
The licensee has proposed exceptions to operability requirements for the Power Level-High trip function in Mode 3, as follows:
Trip does not need to be operable if all the control rod drive mechanisms are de-energized or if the RCS boron concentration is greater than or equal to the refueling concentration of Specification 3.9.1.
Thus, the Power Level-High trip need not be operable when continuous rod withdrawal is precluded. The Power Level-High trip function is not relied upon to terminate any other accidents or transients initiated from Mode 3.
The licensee has also proposed suitable changes to the TS Bases that are consistent with the proposed TS changes, s
The proposed changes to the TS are consistent with the licensee's revised evaluation of the continuous control rod withdrawal from suberitical conditions and assure that, should this incident occur, the consequences would be accept-able.
In the case of the continuous rod withdrawal from subcritical conditions, a DNBR of greater than or equal to 1.30 assures continued fuel integrity.
Accordingly, the proposed change to the TS are acceptable.
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ENVIRONMENTAL CONSIDERATION s
This amendment involves a change in the installation or use of a facility-component located within the restricted area a's defined in 10 CFR Part 20 or The staff has determined that the a change in surveillance requirements.
amendment involves no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational The Commission has previously published a proposed finding radiation exposure.
that the amendment involves no significant hazards consideration and there has Accordingly, the amendment meets the been no public comment on such finding.
eligibility criteria for categorical exclusion set forth in 10 CFR S51.22(c)(9).
Pursuant to 10 CFR 551.22(b), no er.vironmental impact statement or environmental assessment need be prepared in connect lon with the issuance of the amendment.
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 the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.
Date: April 21,1987 Principal Contributor:
D. Jaffe
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