ML20235S440
| ML20235S440 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 09/29/1987 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20235S413 | List: |
| References | |
| NUDOCS 8710080501 | |
| Download: ML20235S440 (5) | |
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' NUCLEAR REGULATORY COMMISSION E
WASHINGT.ON, D. C. 20G55
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION 1
SUPPORTING AMENDMENT NO. 12 TO FACILITY OPERATING LICENSE NO. OPR-21
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NORTHEAST NUCLEAR ENERGY COMPANY i
MILLSTONE NUCLEAR POWER STATION, UNIT NO. 1 i
DOCKET NO. 50-245 q
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1.0 INTRODUCTION
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By letter dated December 16, 1986 and supplement dated January 30, 1987, the Northeast Nuclear Energy Company (NNECO) has proposed two separate 4
changes to the Millstone Nuclear Power Station, Unit No. I technical l
specifications (TS).
First, the licensee requested that the set points
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of_the Steam Tunnel Ventilation Radiation Monitors be permanently changed to correspond to the limits of monitors in their recently issued Radiological Effluent Technical Specification, and Offsite Dose Calculation Manual (0DCM).
Secondly, Northeast Utilities requested that the Technical Specification set points of both the Main Steam Line Radiation Monitors and Steam Tunnel
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Ventilation Radiation Monitors,(MSLRMs) be temporarily increased to facilitate i
planned water chemistry testing with respect to the addition of hydrogen.
The temporary set point change is required based on prior experience showing j
that the radiation levels may increase during the test by a factor of five q
over the radiation levels experience routinely.
j 2.0 EVALUATION 2.1.1 Set Point Changes for Steam Tunnel Ventilation Radiation Monitors The Steam Tunnel Ventilation Radiation Monitors provide isolation of the steam tunnel and direct releases to the Standby Gas Treatment System (SGTS) upon indication of high airborne activity levels in the steam tunnel. The purpose of the isolation is to maintain instantaneous releases to the ene vironment below the normal operation of 10 CFR Part 20 limits.
j The licensee preposed changes would allow:
(1) a permanent increase to the trip set point for the ventilation monitors from 12 mr/hr to 50 mr/hr for normal operation and, (2) a temporary increase up to 100 mr/hr during a hydrogen injection test provided that the difference between the increased set point and the calculated value of the background radiation levels ex-pected during the test does not exceed 50 mr/hr.
The licensee states in the December 16, 1986, submittal that the Steam Tunnel Ventilation Radiation Monitors are not credited in any design 8710080501 070929 PDR ADOCh 05000245 P
PDR r-
- basis accident and their only safety function is to limit instantaneous releases to within 10 CFR Part 20 limits. "The licensee also indicated that that the set point is intended to be based on their current Radiological Effluent Technical Specifications and ODCM.
Based on the staff's review of the Millstone 1 Radiological Effluent Technical Specifications and the licensee's ODCM, the staff finds that the permanent change in the Steam Tunnel Ventilation Radiation Monitors set point to 50 mr/hr is acceptable, because the normal operational limits of 10 CFR part 20 will continue to be met by the licensee. Furthermore, on the basis of its previous reviews i
of hydrogen addition testing, the staff finds that the temporary change in the ventilation monitors set point is acceptable, because it will prevent unnecessary actuation of the SGTS due to spike increases in the steam tunnel radiation background.
2.1.2 Scram and Isolation Set Points for Main Steam High Radiation Monitors The MSLRMs provide reactor scram as well as reactor vessel and primary containment isolation signals upon detection of high activity levels in the main steam lines. Additionally, these monitors serve to limit the radioactivity released in the event of fuel failures.
The licensee's proposed TS changes would allow adjustments to be made to the normal background radiation level and associated trip set points for the MSLRMs at reactor power levels greater than 20% of rated power. The adjustments are needed to accommodate the expected increase in main steam activity levels j
as a result of planned tests involving hydrogen injection into the reactor coolant. This is primarily due to anticipated increased nitrogen-16 (N-16) levels in the reactor coolant.
.The licensee states that there are no postulated accidents, including the control rod drop accident (CRDA), which take credit for the main steam line high radiation scram and isolation signal. The staff notes that for a
a CRDA, and for any accident. causing fuel failures, the MSLRMs function is to limit the transport of activity released from failed fuel to the turbine and condensers. This is done by initiating closure of the main steam isolation valves, which isolate the reactor vessel. Main steam line high radiation will also produce a reactor scram signal and will
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isolate the mechanical vacuum pump and the gland seal steam exhaust system i
to reduce leakage of fission products to the atmosphere from the turbine
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and condensers.
Generic analysis of the consequences of a CROA have shown that fuel failures I
are not expected from a CRDA occurring at greater than 10% power. As power increases, the severity of the accident rapidly decreases, due to I
the effects of increased void formation and increased Doppler feedback.
Since the set point adjustments will be restricted to power levels above 20% of rated power, the staff concludes that the currently approved CP.DA analysis for Millstone 1 is bounded appropriately and remains valid.
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j 2.2 Radiation Protection /ALARA The staff-has t-eviewed the proposed TS change to modify permaner.tly the.
1 set point on Millstone.1 ventilation radiation monitors to 50 mr/hr with j
respect to radiation protection to the public. Since no increase is to be
. allowed.in releases to the environment (i.e., no change'in the station's Radiological Effluent Technical Specifications is being requested) and the proposed set point will continue to restrict releases below 10 CFR Part 20
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limits on the basis of the licensee's ODCM methodology, the. staff finds that the licensee's request is acceptable.
The staff also has reviewed the proposed TS changes in reference to the j
radiological implications of the dose rate increases-associated with N-16 1
equilibrium changes during hydrogen addition at boiling water reactors (BWRs).. In addition, the review addressed the radiation protection /ALARA measures for the course of the planned test, in accordance with 10 CFR 20.1(c) and Regulatory Guide 8.8, "Information Relevant to Ensuring that Occupational j
Radiation Exposures.at Nuclear Power Stations Will Be As Low As Is Reasonably Achievable (ALARA)."
j An overall objective of the test is to determine general in-plant and site boundary dose rate increases due to hydrogen addition. The licensee has indicated that normal health physics /ALARA practices and procedures for Millstone I will be continued throughout the test. Additionally, the licensee has indicated that specific locations will be identified where temporary shielding may be needed for long-term implementation of hydrogen injection.
The staff also has reviewed the licensee's proposed dose control measures and surveillance efforts planned for the hydrogen addition test. Tests of this type have been proposed and conducted at other operating BWRs, following staff review and approval of similar TS changes. The-test conditions, as identified by the licensee, as well as the measures proposed for radiation protection /ALARA at Millstone 1, are consistent with those utilized at the other BWRs during their successful hydrogen addition tests.
None of these tests involved any significant, unanticipated, radiological exposures or releases.
2.3 Hydrogen Storage and Distribution System l
.By letter dated January 30, 1987, the licensee provided information on the hydrogen and oxygen storage and distribution system to facilitate the Hydrogen Water Chemistry pre-implementation test. The licensee's hydrogen and oxygen storage and addition system is designed to reduce the potential hazard to safety-related systems and meets the applicable parts of the BWR Owners Group, " Guidelines for Permanent BWR Hydrogen Water Chemistry F
Installations." The staff reviewed this submittal against the guidance provided in NRC Branch Technical Position CMEB 9.5-1 of NUREG-0800.
s The pre-implementation test will be conducted with the guidance of General-Electric (GE), taking into consideration the lessons learned from six other a
hydrogen injection. tests previously performed by GE. All applicable National Fire Protection Association _and Occupational Safety and Health Administration requirements will be met during the test. The hydrogen injected into the condensate booster pump suction is stored as compressed gas in tube tank i
trucks. The hydrogen distribution system contains two excess flow check valves, in series, to limit the release of hydrogen in the event of a pipe break. To prevent the accumulation'of combustible concentrations of hydrogen at the condensate booster pumps, near the hydrogen flow control valves, and along the hydrogen supply line, the hydrogen lines will be leak tested prior to the test and monitored for hydrogen concentrations during the test.
The monitors will alarm and isolate the hydrogen supply line if hydrogen concentration exceeds 2%.
Oxygen will. be injected upstream of the off-gas recombiner to ensure that all excess' hydrogen in the off-gas stream is recombined. The recombiner outlet flow will be monitored to ensure the presence of excess oxygen. The
The Millstone Nuclear Power Station recently has implemented sodium hypochlorite control of bio-fouling of the cooling water systems.
Consequently, all chlorine gas has been removed from the site. This eliminates the potential hazard associated with a simultaneous chlorine and hydrogen release.
I On the basis of the above provisions, we conclude that the licensee's hydrogen and oxygen storage and addition system meets 10 CFR 50.48 and General Design Criterion 3, as well as Branch Technical Position CMEB 9.5.1 of NVREG-0800, and is, therefore, acceptable.
On the basis of the adequacy of the licensee's radiation protection /ALARA program, utilization of special surveys to monitor dose rate increase on site and at the site boundary, the capability to monitor for fuel failures, as well as the success of similar efforts at other operating BWRs, the staff finds that the licensee's request is acceptable.
3.0 ENVIRONMENTAL CONSIDERATION
This amendment involves a change to a requirement with respect to the installation or use of facility components located within the restricted area as defined -in 10 CFR Part 20. The staff has determined that the amendment involves no significant increase in the amounts, and no signifi-cant change-in the types, of any effluents that may be released offsite and that there is no significant increase in individual or cumulative occupational radiation exposure. The Commission has previously issued a proposed finding that this amendment involves no significant hazards L
consideration and there has been no public comment on such finding.
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- Accordingly, this amendment meets the eligibility criteria for categorical 7
exclusion set forth in 10 CFR 51.22(c)(9). Pursuant to 10 CFR 51.22(b) no environmental impact statement or environmental assessment need be prepared in connection with the issuance of this amendment.
4.0 CONCLUSION
The staff has 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 this amendment will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributor:
M. Lamastra Dated: September 29, 1987 I
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