ML19345A428
| ML19345A428 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 01/24/1963 |
| From: | Bryan R US ATOMIC ENERGY COMMISSION (AEC) |
| To: | |
| Shared Package | |
| ML19345A427 | List: |
| References | |
| NUDOCS 8011210388 | |
| Download: ML19345A428 (3) | |
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U UNITED STATES ATOMIC ENERGY COM'1ISSION HAZARDS ANALYSIS BY WE RESEARCH AND POWER REACTOR SAFETY BRANCH DIVISION OF LICENSING AND REGULATION IN THE MATTER OF k
YANKEE ATOMIC ELECTRIC COMPANY f.
PROPOSED CHANGE NO. 31 P
DOCKET NO. 50-29 Introduction Pursuant to the provisions of Section 50.59 of the Commission's regulations,
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Yankee Atomic Electric Company has requested authorization of a temporary waiver of the requirements of operating restriction D 2.d.(6) of the technical
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specifications attached as Appendix A to License No. DPR-3.
This operating restriction requires that the reactor not be operated above 15 hk electric unless the boron concentration in the main coolant system is less than 80 ppm.
It provides further that the reactor will noc be operated below 15 hN electric with more than 220 ppm of boron in the main coolant system except during normal startups or during low power physics testing.
Yankee has requested waiver of these requirements in order to perform a test to obtain further information concerning the use of boric acid during operation of the reactor at power.
The test which would be performed would last for a period of from 2 to 6 weeks and would involve the use of boric acid in the main coolant system in concentrations up to 400 ppm.
During this period, the reactor would be operated at power levels up to the presently authorized maximum steady state power IcVel of 540 Mw thermal.
Discussion Yankee requested and was granted authorization to perform a similar test of the use of boric acid in the primary system of the reactor during Core I operation.
This authorization was issued as a part of Change No. 10 to License No. DPR-3, and the Division of Licensing and Regulation's hazards analysis in conjunction with Change No.10 presented a discussion of the principal safety questions which were involved in the performance of this test.
Two factors are associated with the test now proposed which were not fully considered in connection with the test previously authorized.
The first is that during the Core I test there was an unexplained long term loss of reactivity which resulted in the t est being terminated after one week.
The second is that Yankee proposes to operate the reactor at power levels up to 540 hk thermal during the test, which is an increase from the maximum power level of 435 ok thermal authorized for the prior test.
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c p e The previous use of boric acid in the primary system while operating the reactor at power was subject to the restriction that the test would be dis-continued if at any time the summation of uncertainty in reactivity measurement plus any unexplainable reactivity change exceeded.00S.
Following addition of boric acid to the system, an unexplained gradual loss of reactivity ensued which resulted in the above limit being approached.
As a result, Yankee, teminated the test one week after it had commenced.
Subsequent to the test, it was concluded that high pH, possibly resulting from an inadvertent addition of nitrogen to the primary coolant system, P
may have increasci the reactivity of the core the day before the test bepn.
Y-F The results of s Usequent tests performed by Yankee of the effect on reactivity of an increase in pH have substantiated such a conclusion, p~
Yankee believes that the gain in reactivity resulting from the high pH could have been lost during the test and may have contributed to the observed unexplained reactivity change. However, it is not completely clear that
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the loss of reactivity that occurred during the previous test can be ascribed cntirely to the abnomal pH and reactivity conditions which were present in the primary system when the test began.
From the information which has been
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submitted by Yankee, we have concluded that the possibility of boron plate-6 out on core surfaces during operation at power with boron in the primary P -
sysrem cannot be completely ruled out.
However, in view of the fact that the unexplained reactivity loss during the Core I test occurred over a long g:
period of time and the test was terminated when the unexplained reactivity k
change approached.008, we do not believe that the unexplained reactivity M=
loss resulted in a hazardous condition.
Accordingly, it is~our opinion that the unexplained reactivity change which occurred should not preclude authori-F:
zation'of the performance of a subsequent experiment of the same type under the same restrictions with respect to an unexplained reactivity change.
Yankee was authorized to pe* form the previous test at power Icvels up to.4SS
?k thermal. They have pwposed that the test now contemnlated be carried out at power IcVels up to a maximum of 540 the thermal. We believe that, before operating at power Icycls in excess of 4S5 !N thermal during the test, Yankee should make in-core instrumentation measurements at the-latter power Icyc1 with boric acid in the primary system.
On the basis of these measurements, Yankee should calculate the steady state and transient DNB ratios at power IcVels up to 540 the thermal with the amount of horic acid in the primary system proposed to be used in the tests at these -ower -
j Icycls, and should not proceed to a power level where these ratios would be less than those presented for 540 Mw thercal operation in the hazards summary report for the Yankee reactor. These minimum values have previously been determined to be acceptabic from a safety standpoint for reactor operations up to 540 39.
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P 9 0 t M IGIN A l.
. Conclusion
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Subject to the above requirements regarding measurements with incore instrumentation and calculations of minimum DNB ratios, we have concluded that the proposed change does not present significant hazards considerations not described or implicit in the ha:ards summary report, and that there is reasonable assurance that the health and safety fo the public will not be
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endangered, r'
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Origir.a! signed by Pdert H. Bryan L.-
Robert H. Bryan, Chief Research 6 Power Reactor Safety Branch Division -of Licensing and Reguhtion j AN 14 N,O Date:
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