ML19351D759
| ML19351D759 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 12/05/1962 |
| From: | Bryan R US ATOMIC ENERGY COMMISSION (AEC) |
| To: | |
| Shared Package | |
| ML19351D758 | List: |
| References | |
| NUDOCS 8011180259 | |
| Download: ML19351D759 (2) | |
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h HAZARDS ANALYSIS BY THE RESEARCH AND POWER REACTOR SAFETY BRANCH DIVISION OF LICENSING AND REGULATION IN THE MATTER OF g'.:.
YANKEE ATOMIC ELECTRIC COMPANY PROPOSED' CHANGE NO. 26 DOCKET NO. 50-29 Introduction Paragraph D.2.1. of the Technical Specifications attached as Appendix A to Yankee Atomic Electric Company's operating license states that routine and periodic tests will be made at the times and in the manner set "forth in Section 509 of the license application. Section 509 specifies that measurements of the reactor power coefficient and the moderator t~emperature coefficient will be made at 2000 equivalent fu' ll power hour intervals.
=E By Proposed Change No. 26, dated July 20, 1962, Yankee requested authori-zation to revise Section 509 of the license application so as to eliminate the requirement for measurement of the power coefficient and moderator temperature coefficient of reactivity at 2000 equivalent full power hour intervals.
In lieu of these periodic measurements, Yankee would institute a modified program of determining the value of the two reactivity coefficient values.
Discussion During construction of the Yankee reactor, concern regarding tha effects of plutonium build-up on kinetic reactivity coefficients resulted in Yankee engaging Westinghouse cnd Nuclear Development Corporation of America to perform theoretical calculations to determine the extent of such effects.
IE The calculations indicated that the plutonium produced in the Yankee core E,_
would not significantly affect these coefficients.
Although considered desirable, critical assembly experiments to confirm the results of the calculations prior to Core I operation did not appear to be practicable.
It was decided, therefore, that measurements should be performed during core life to confirm the predicted effects of plutonium build-up.
Accordingly,
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Yankeo's provisional license provided that six months after its issuance Yankee would submit a description of the specific experimental procedures f
to be followed in determining the effects of plutonium build-up at intervals during core life.
The abova provision was complied with in Yankee's Six Months Operating Report issued February 13, 1961.
In this document, Yankee outlined their test procedures for determining the effects on reactivity coefficient due to plutonium build-up.
These tests consisted of measuring the power coefficient and moderator temperature coefficient at operating temperature and were to be performed at 2000 equivalent full power hour intervals during core life.
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... Yankee carried out the proposed program 'during the life of Core I, except fi for the 8000 hour0.0926 days <br />2.222 hours <br />0.0132 weeks <br />0.00304 months <br /> test which they were authorized to omit.
The results of the measurements which were performed by Yankee did not indicate any significant change in the two coefficients.
Both remained nearly constant throughout core life.
The moderator temperature coefficient changed from
-3.10 x 10-4 at the beginning of core life to -2.84 x 10-4 4 end of core life, while the power coefficient changed from //*F at the
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,33 x 10-4 to
.40 x 10-4 4//l*M thermal.
Yankee concluded from the above results that the effects of plutonium build-up on reactivity coefficients are insignificant in their reactor.
They i:
have, therefore, proposed that the requirements for the 2000 hour0.0231 days <br />0.556 hours <br />0.00331 weeks <br />7.61e-4 months <br /> reactivity coefficient measurements be eliminated.
In lieu of the 2000 hour0.0231 days <br />0.556 hours <br />0.00331 weeks <br />7.61e-4 months <br /> measure-L ments, an alternate program for determining these reactivity coefficient values would be instituted. The two reactivity coefficients would be experimentally determined during the initial startup after each fuel loading.
Data obtained during scheduled generator load changes throughout core life would be used for power coefficient determinations, and data obtained during scheduled plant shutdown would be used for temperature coefficient measure-
- ments, b
In view of the past interest of the Atomic Energy Commission's Advisory
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Committee on Reactor Safeguards (ACRS) in regard to the matter of the potential reactivity coefficient changes due to plutonium build-up in the E
Yankee reactor core, the matter of Proposed Change No. 26 was presented to the Committee for its information and comment. The ACRS considered the Proposed Change at its August 23-25, 1962 meeting.
In a letter to the Chairman of the Atomic Energy Commission, dated August 25, 1962, the ACRS stated that it believed that the change in frequency of the 2000 hour0.0231 days <br />0.556 hours <br />0.00331 weeks <br />7.61e-4 months <br /> tests may be allowed without undue hazard to the health and safety of the public.
Conclusion Tne alternate program of measuring reactivity values appears to provide an adequate means of detecting any anomalous kinetic reactivity coefficient behavior due to plutonium build-up.
In view of this proposed program and since the theoretical calculations and the Core I test results did not indicate appreciable kinetic reactivity coefficient effects due to plutonium build-up, we do not believe it necessary to require Yankee to continue the reactivity coefficient measurements at 2000 hour0.0231 days <br />0.556 hours <br />0.00331 weeks <br />7.61e-4 months <br /> intervals.
Furthermore, it is our opinion that Proposed Change No. 26 does not present significant hazards considerations not described or implicit in the hazards summary report and that there is reasonable assurance that the health and safety of the public will not be endangered.
CdgiNI sIgd 1 kkf IL Er 7
Robert H. Brycn,gaChief Research 6 Power Reactor Safety Branch Division of Licensing and Regulation 0
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