ML20138F817
| ML20138F817 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 12/09/1985 |
| From: | Opeka J NORTHEAST NUCLEAR ENERGY CO., NORTHEAST UTILITIES |
| To: | Noonan V Office of Nuclear Reactor Regulation |
| References | |
| RTR-REGGD-01.097, RTR-REGGD-1.097 A05390, A5390, NUDOCS 8512160176 | |
| Download: ML20138F817 (3) | |
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v N l#TILITIES cenerai Ovvices. seiaen street. Berlin. Connecticut sC$NisSNE.5 P.O. BOX 270
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HARTFORD, CONNECTICUT 06141-0270 L
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(203) 665-5000 December 9,1985 Docket No. 50-423
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A05390 Director of Nuclear Reactor Regulation Mr. V. Noonan, Director PWR Project Directorate #5 Division of PWR Licensing - A U.S. Nuclear Regulatory Commission Washington, D.C. 20555
References:
(1) B. 3. Youngblood letter to W. G. Counsil, Request for Additional Information Conformance to Regulatory Guide 1.97, dated February 12, 1985.
(2)
- 3. F. Opeka letter to B. 3. Youngblood, Conformance to Regulatory Guide 1.97, Revision 2 Guidelines, dated May 28,1985.
Dear Mr. Noonan:
Millstone Nuclear Power Station, Unit No. 3 Regulatory Guide 1.97, Containment Sump Water Temperature The NRC position in Regulatory Guide 1.97, Revision 2, with respect to containment cooling systems requires that instrumentation be available in order to estimate the containment heat removal capability. For Millstone Unit No. 3, the NRC required that Northeast Nuclear Energy Company (NNECO) should either supply the recommended instrumentation or provide a justification for not supplying it (Reference (1)). In Reference (2) NNECO provided a justification for not providing the containment sump water temperature as recommended by Regulatory Guide 1.97, Revision 2. In a recent telephone conversation, the Staff indicated our justification was not sufficient and requested additional clarification to support our justification for not providing the recommended instrumentation to monitor the containment sump water temperature.
Attachment I discusses why containment sump water temperature, or its equivalent, is not provided as part of Millstone Unit No. 3 Regulatory Guide 1.97 licensing basis. This submittal should fully resolve the Staff's concern regarding the containment sump water temperature.
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%.. If there are any questions, please contact our licensing representative directly.
(45 Very truly yours,
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NORTHEAST NUCLEAR ENERGY COMPANY
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NORTHEAST NUCLEAR ENERGY COMPANY
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J. F. Open V
Senior Vice President STATE OF CONNECTICUT )
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- Then personally appeared before me 3. F. Opeka, who being duly sworn, did state that he is Senior Vice President-of Northeast Nuclear Energy Company, a Licensee herein, that be is authorized to execute and file the foregoing
'information. in the name and on behalf of the Licensees herein and that the -
statements contained in said information are true and correct to the best of his knowledge and belief.
- M W Onk' l$otary Publitfi My Commission Expires Marcn 31,1988 a
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i Attachm' ent I The NRC position in Regulatory Guide 1.97, Revision 2, with respect to '
containment cooling systems requires that instrumentation be available in order to estimate the containment heat removal capability. For Millstone Unit No. 3, the NRC is requiring that a containment sump water temperature or equivalent be provided. ' With this sump temperature as the recirculation heat exchanger inlet -temperature, along with recirculation flow and heat exchanger outlet temperature, a heat removal rate can be calculated.
The capability to perform this calculation has not been supplied at Millstone Unit No. 3 as part of the Regulatory Guide 1.97 design basis for the following reasons.
During accident mitigation the operating staff will be following the instructions
- provided in the plant Emergency Operating Procedures. These procedures do not make use of the heat removal rate as a basis for makin~g decisions or taking mitigating actions (i.e., the emergency procedures never call for the operating staff to do such a calculation). Containment pressure, along with containment
. temperature, are sufficient to determine whether heat removal from the containment atmosphere is adequate. Safety analyses included in Chapter 6 of the Millstone Unit No. 3 FSAR demonstrate that the heat removal systems -
provided are adequate to maintain the containment integrity.
Calculating a heat removal rate will be of limited usefulness to the operating i
staff since they cannot accurately estimate the -heat addition to the containment. If the operating staff knows the heat removal rate but not the heat addition rate,' it is difficult to perform a heat balance calculation. As such the operators must rely on containment pressure to verify adequate heat removal rate; an increase in containment pressure indicates that more heat is being added to the containment that is being removed at that particular instant.
Additionally, the definition of Type :D variables in Regulatory Guide 1.97,
. Revision 2, specifies that "those variables that provide information to indicate the operation of individual safety systems...are to-help the operator make appropriate decisions in using the individual systems important to safety in mitigating the consequences of an accident.". This requirement is fulfilled by using the containment pressure indication.
This definition does not require Type D variables on the basis of use of by. personnel in the technical support facilities.
The existing instrumentation is available for their use in their evaluations. 'However, upgrading instrumentation for this use is not considered to be within scope of this guide.
The Millstone 3 Regulatory Guide 1.97 design basis has been to provide the operating staff with all the indications necessary to perform the actions of the emergency operating procedures. The procedures never require that an estimate
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of heat removal rate : from ~ the sump be calculated.
Rather, containment pressure which is provided, is used to verify and ensure adequate heat removal.
Thus, containment sump water temperature (or its equivalent) has not been provided.
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